analysis of water pollution in freshwater inle lake based on eutrophication

ANALYSIS OF WATER POLLUTION IN

FRESHWATER INLE LAKE BASED ON

EUTROPHICATION

PhD DISSERTATION

MAR LAR HTWE

DEPARTMENT OF ZOOLOGY

UNIVERSITY OF YANGON

MYANMAR

NOVEMBER, 2008

ii

ACKNOWLEDGEMENT

I would like to express my profound gratitude to Professor Dr. Maung

Maung Gyi, Head of Zoology Department, University of Yangon for his kind

permission to conduct this research.

Grateful thanks to Professor Dr. Khin Maung Swe, Department of

Zoology, Dagon University, for his continuous encourage, constructive advice,

valuable suggestions, and scholastic supervision and guidance of this research

work.

I extend my thanks to Integrated Community Development Project

office of UNDP in Nyaung Shwe Township, Southern Shan State and

Freshwater Aquaculture Research Chemical Laboratory, Department of

Fisheries, Tharkayta Township, Yangon for their technical help in analyzing

water parameters.

I would like to express my sincere thanks to Nagao Natural Environment

Foundation (NEF), Japan and Forest Resource Environment Development and

Conservation Association (FREDA), Myanmar for partially support of

financial.

I also wish to express my thanks to Dr. Moe Kyi Han, Dr. Tint Moe Thu

Zar, Dr. Khin Lay Yee and Dr. Nway Nwe Aye who have kindly assisted me in

graphic presentation.

My heartfelt gratitude goes to all my sisters and brothers, for their

consistent encourage, understanding and financial support.

Last but not the least, I am especially grateful to my husband, U Kyaw

Thant, for his moral encouragement and financial support rendered throughout

the study period.

iii

ABSTRACT

The present study was conducted in the Inle Lake, Nyaung Shwe

Township, Southern Shan State. Inle lake is the third largest lake in Myanmar

in which several tens of thousands of people live in the lake. The lake has

several risk factors that could pollute its water as the chemical fertilizers and

pesticides are being continually used in the agricultural farms in the area. Six

study sites were selected to collect the water samples. Water samples were

collected monthly from the year 2006 to 2007 to determine the pollution level

and eutrophication. Increased nutrient loading can stimulate algal growth found

abundantly in the lake.

Six physical parameters consisting water depth, turbidity, water

temperature, electrical conductivity, hardness, and total dissolved solids (TDS),

and six chemical parameters consisting pH, arsenic, chlorides, fluoride

concentrations and dissolved oxygen (DO), biochemical oxygen demand

(BOD), and two nutrient parameters of nitrates and phosphates levels were

investigated to determine the pollution level.

All parameters were analysed by using comparative and correlation

statistical methods. Monthly means and the range of each parameter were

calculated. The data were presented by graphic presentations. Two water

parameters, nitrates and phosphates, were observed to be higher than WHO

standard level, while four parameters, DO, BOD, chlorides and fluoride, were

found to lower than the WHO standards. Hence the use of chemical fertilizer in

this lake is assumed to start water pollution contributing to eutrophication.

Lowering of DO could also affect aquatic fauna in the lake. Suggestions for

future work are outlined based on the recorded data.

iv

TABLE OF CONTENTS

Content Page

ACKNOWLEDGEMENT ….. ii

ABSTRACT ….. iii

TABLE OF CONTENTS ….. iv

LIST OF FIGURES ….. vii

LIST OF PLATES ….. ix

LIST OF TABLES ….. x

CHAPTER 1 INTRODUCTION ….. 1

CHAPTER 2 REVIEW OF LITERATURE ….. 5

2.1 Water ….. 5

2.2 Eutrophication ….. 8

2.3 Previous Inle Condition ….. 12

2.4 Recent Inle Condition ….. 13

CHAPTER 3 MATERIALS AND METHODS ….. 14

3.1 Study area ….. 14

3.2 Study site ….. 14

3.3 Study period ...... 14

3.4 Materials ….. 17

3.3 Study period ….. 13

3.4.1 Equipment, apparatus and testkits …... 17

3.5 Methods …... 17

3.5.1 Collection of water samples ….. 17

3.5.2 Physicochemical analysis of water samples ….. 18

v

3.6 Data analysis ….. 18

CHAPTER 4 RESULTS ….. 21

4.1 Physical parameters ….. 21

4.1.1 Water depth ….. 21

4.1.2 Electrical conductivity ….. 24

4.1.3 Total dissolved solid ….. 24

4.1.4 Turbidity ….. 27

4.1.5 Hardness ….. 27

4.1.6 Water temperature ….. 30

4.2 Chemical parameters ….. 33

4.2.1 Arsenic ….. 33

4.2.2 Chloride ….. 36

4.2.3 Fluoride ….. 36

4.2.4 Water pH ….. 39

4.2.5 Dissolved oxygen ….. 42

4.2.6 Biochemical oxygen demand ….. 47

4.3 Nutrient pollutants ….. 50

4.3.1 Nitrate nitrogen, NO3-N ….. 50

4.3.2 Phosphate ….. 53

4.4 Correlation among water parameters

in Inle Lake ….. 58

4.4.1 Physical parameters and water pH ….. 58

4.4.2 Physical parameters and DO ….. 58

4.4.3 Physical parameters and BOD ….. 62

vi

4.4.4 Physical parameters and fluoride ion

concentration ….. 62

4.4.5 Physical parameters and chlorides ….. 65

4.4.6 Chemical parameters and electrical

conductivity ….. 65

4.4.7 Water temperature and nitrates ….. 69

4.4.8 Total dissolved solids and nitrates ….. 69

CHAPTER 5 DISCUSSION ….. 72

SUMMARY ….. 83

SUGGESTIONS FOR FUTURE WORK ….. 84

REFERENCES ….. 85

vii

LIST OF FIGURES

Figure Page

3.1 Map of study area ….. 15

3.2 Six study sites of Inle Lake (A) Kyezagone (B) Lethit

(C) Mwepwe (D) Kela (E) Centre of the Lake and

(F) Namlit chaug ….. 16

4.1 Monthly variation of water depth (cm) in six study sites

(March 2006 to February 2007) ….. 23

4.2 Monthly variation of electric conductivity ((μs cm-1) in

six study sites (March 2006 to February 2007) ….. 26

4.3 Monthly variation of total dissolved solid (mg L-1) in

six study sites (March 2006 to February 2007) ….. 29

4.4 Monthly variation of hardness (mg L-1) in six study

sites (March 2006 to February 2007) ….. 32

4.5 Monthly variation of temperature (°C) in six study sites


4.6 Monthly variation of chloride (mg L-1) in six study sites


4.7 Monthly variation of fluoride (mg L-1) in six study sites


4.8 Monthly variation of pH in six study sites


4.9 Monthly variation of dissolved oxygen (mg L-1)

viii

in six study sites (March 2006 to February 2007) ….. 46

4.10 Monthly variation of biochemical oxygen demand (mg L-1)

in six study sites (March 2006 to February 2007) ….. 49

4.11 Monthly variation of nitrate (mg L-1) in six study


4.12 Monthly variation of phosphate (mg L-1) in six study


4.13 Correlation between physical parameters and water pH

in Inle Lake ….. 60

4.14 Correlation between physical parameters and dissolved

oxygen (DO) ….. 61

4.15 Correlation between physical parameters and biochemical

oxygen demand in Inle Lake ….. 63

4.16 Correlation between physical parameters and fluoride

ion concentration in Inle Lake ….. 64

4.17 Correlation between physical parameters and chloride

ion concentration in Inle Lake ….. 66

4.18 Correlation between chemical parameters and electrical

conductivity in Inle Lake ….. 67

4.18 Correlation between chemical parameters and electrical

conductivity in Inle Lake ….. 68

4.19 Correlation between nitrate compounds and physical

parameters in Inle Lake ….. 71

LIST OF PLATES

ix

Plate Page

3.1 Collection sites of water samples showing

different conditions ….. 19

3.2 Collection water samples and Meters and Test-kits ….. 20

4.1 Sources of nutrients and pollutants ….. 56

4.2 Different types of bloom of floating and submerged plants

that affect on the water quality of Inle Lake ….. 57

LIST OF TABLES

x

Table Page

4.1 Monthly water depths (cm) at different water sampling

sites during study period ….. 22

4.2 Monthly electric conductivity (μs cm-1) at different water

sampling sites during study period ….. 25

4.3 Monthly total dissolved solids (mg L-1) at different water


4.4 Monthly hardness (mg L-1) at different water sampling sites

during study period ….. 31

4.5 Monthly water temperature (°C) at different water


4.6 Monthly chloride ion concentration (mg L-1) at different

water sampling sites during study period ….. 37

4.7 Monthly fluoride ion concentration (mg L-1) at different water


4.8 Monthly water pH values at different water sampling sites

during study period ….. 43

4.9 Monthly dissolved oxygen (mg L-1) at different water


4.10 Monthly biochemical oxygen demand (mg L-1) at different


4.11 Monthly nitrate ion concentration (mg L-1) at different water


4.12 Monthly phosphate ion concentration (mg L-1) at different

xi


4.13 Values of coefficient of correlation and regression equation ….. 59

1

CHAPTER 1

INTRODUCTION

Inle lake is a very popular resort as traditional Inle festival, nice scene

with leg rowing, very beautiful big horn-shaped fishing trap, seasonal festival

one of the ecotourism sites in Myanmar. Inle Lake is located on the Shan

plateau of East Myanmar, in Thanlwin river basin and is the third largest

natural lake in Myanmar. The basin is in a broad North-South valley between

two limestone ridges, rising to 1200 meters above sea level, 19.8 meters long

and 11.6 meter wide, elongated and fairly shallow, an area of 5.618 sqkm, with

a maximum measured depth of 4 meter (Davies, 2004).

Water pollution is defined as any contamination of water that lessens its

value to humans and nature. Pollution represents imbalance of one or more

elemental cycles. Water pollutants for the lakes are sediments, nutrients,

oxygen demanding organic wastes, thermal pollution, disease organism, and

toxic organic wastes by United Nation Environmental Programme-

International Environmental Technology Centre/International Lake

Environment Committee Foundation (UNEP-IETC/ILEC, 2001).

Eutrophication is defined by two water parameters, over enrichment of

micronutrients of phosphate PO4-P and nitrates NO3-N. Eutrophication leads to

the reduction of oxygen and the release and accumulation of toxic substances in

the water that creates the sediments-polluting aquatic environment, which can

then lead to the death of aquatic organisms, and the destruction of ecosystems

and also threat to human health (Eastin, 1977).

Annadale reported in 1918 that the fertility of Inle Lake was very less

and eutrophication started by gradual proceeding of the occurrence of algae,

weed, and some aquatic plants. Several tribes live in the floating islands of the

lake for many years. Currently, the population living in the 360 villages on the

floating islands and around the lake is approximately 110,000 people and

2

produce domestic wastes, human sewages, debris, the wastes of chemical

compounds of inorganic fertilizers, pesticides utilized in the agriculture farms

on the floating island.

Much area of the lake is covered with a luxuriant growth of submerged

and floating-leaved macrophytes. In addition, there are floating mats composed

mainly of grasses. These are the distinct appearance in some degree of

pollution and eutrophication in the lake water. There are extensive areas of

anchored mats and herbaceous marsh, especially around the northern end of the

Lake. Much of the lake-associated herbaceous marsh has been converted to rice

fields and to water gardens.

Direct uses of the Inle Lake are for fishing, water gardening,

transportation, and tourism. Recently, human population becomes high around

the lake, particularly immediately to the north and around the southern and

western margins. Thus, inflow of domestic effluent into the lake may be a

problem; together with general disturbance.

Tourism results in some disturbance through boat trips on the lake and

through the development of resorts on the shores of the lake which may cause

an increase in the flow of domestic effluent into the lake. Oil spill from the

high number of motorized boats in the lake cover the film on the water surface

may make disturbance the aquatic plants for photosynthesis. A large amount of

heat produced by the motor engines of the boats is one the thermal pollution of

the lake water temperature. The development of water gardens is a form of

reclamation and extends to the areas of open water being lost around the

margins.

Siltation is considered to be a major threat during the wet season, when

rain causes erosion of soil which has been exposed by fires in the dry season.

This seems to be especially true for the western inflows, where a delta has been

created which extends into the lake. The major threat is soil erosion, caused by

run off from slopes which have been subject to fire. The area of Inle has

reduced 15% since the British colonial time. Further development of water

3

gardens will decrease the area of open water and increase the threat from

fertilizers and pesticide. Continued stocking of exotic fish species will pose a

great threat to the unique fish fauna (Aung, Nyo, Htut, Thein, Maung, Thu,

Than, Maung, Thant and Htay 2001).

In Inle Lake, there are a lot of floating farms in floating islands and are

made from masses of floating vegetation and are used to grow vegetables in a

form of hydrophonic culture. Flatter areas round the lake and in the basins are

used for rice, vegetables and flowers cultivation. Floating farms are found

around the lake margins, tomatoes being a major crop. The tomato plantation is

the major food from the Inle floating island agriculture and produces about

three tonnes per year and distribute throughout the country. The chemical

pollutants from the farms, human wastes and domestic wastes produced from

the peoples in everyday finally accumulated in the lake and become

contaminated ( Htay, 2001).

Nowadays, farmers who live in this lake use of many kinds of

agricultural chemicals such as pesticides, herbicides, insecticides, fungicides

and fertilizers. These agricultural chemicals affect aquatic species of this lake

in various ways.

The natural beauty of the lake attracts many tourists. Many hotels and

resorts have also been developed on the shore of the lake, which may cause an

increase in the flow of the domestic effluent into the lake, because of

urbanization and floating islands. The aquatic ecosystem in the lake is therefore

being more and more polluted. And it becomes imported to prevent the

biodiversity of Inle Lake. For this reasons there is a need to do a research of

how this pollution effect on the lake and the aquatic mentioned above

ecosystem.

TDS are formed from dissolved minerals which determine the hardness,

acidity, conductivity inturn affecting water colour, taste and odor (Gray, 1999).

Conductivity indicates water's ability to conduct electric current linked

to level of mineral salts in solution in water. Hence conductivity is controlled

4

by the degree to which these salts dissociate into ions. It is measured as

microsemiemens per centimetre (μs cm-1). Natural rivers and lakes have

electrical conductivity (EC) of 10 to 1,000 μs cm-1.

Alkalinity reduces acidity by neutralizing hydrogen (H) ions. Hence

have buffering activity. Carbonates and bicarbonates determine alkalinity.

pH reflects intensity of acidity/alkalinity of water.

Nitrates originate from organic compounds and ammonia through

aerobic oxidation and decomposition of organisms. Nitrates indicate recent

pollution.

Phosphates indicate lake eutrophication. Sources of phosphorous are

human waste and synthetic detergents and fertilizers.

Arsenic (As) is highly toxic. Sources are industry, insecticides, natural

minerals. Dissolved oxygen (DO) indicates water quality. Dissolved oxygen is

inversely proportional to temperature. Maximum value is about 9 mg L-1.

The present investigation is carried out with the following objectives-

- to detect the water parameters of pH, water temperature (T˚C),

Turbidity, Hardness, Electric conductivity (EC), Total Dissolved Solids

(TDS), Chlorides, Fluoride, Dissolved Oxygen (DO), Biochemical

Oxygen Demand (BOD), water level

- to determine the levels of nitrogen and phosphorus compounds that

cause eutrophication

- to correlate the different water parameters

- to analyze the content of nitrates and phosphates influence

eutrophication process base upon data from surveyed sites

- to evaluate the pollution and eutrophic level of the Inle Lake

5

CHAPTER 2 REVIEW OF LITERATURE

2.1 Water

Simmonds (1962) also stated that pollution is 'the presence in a water of

any substance, physical, chemical or biological, which renders that water

unsuitable or unfit for some domestic purpose.

Beeton (1965) presented as evidence for the eutrophication of the St.

Lawrence Great Lakes an increase in the dissolved salt content of these waters.

Chemical species that make up the bulk of the total salts in most lakes are

calcium (Ca++), magnesium (Mg++), sodium (Na+), potassium (K+), sulfate

(SO4-), bicarbonate (HCO3

-) and chloride ( CL-). Sometimes nitrate (NO3-)

concentrations are encountered in ground waters in amounts that contribute to

the dissolved salts or specific conductance of the water. With the exception of

nitrate, all of these species play minor roles in aquatic plant production of a

lake, i.e. their concentrations are in sufficient excess so that they do not limit

the plant production. Therefore, high total salts in a lake usually mean that the

lake also has a high content of aquatic plant nutrients.

Beeton (1965) was the result of a greater degree of cultural activity in

the lake's drainage basins and thus an increased flux of many of the common

cations and anions normally found in lakes. As will be show later, associated

with the increase in cultural activity, a higher nitrogen and phosphorus flux will

also occur. Although the total amounts of nitrogen, phosphorus and other

aquatic plant nutrients are insufficient to be determined as a part of the

dissolved salts or specific conductivity, they are sufficient to cause excessive

growths of algae and other aquatic plants in lake Erie and parts of the Great

Lakes. Even though these salts probably do not significantly contribute to the

nutrient for aquatic plants, their build up in Great Lakes is of major concern

and will require their removal from some waste waters in the foreseeable

future.

6

Tarzwell (1965) ties the definition to usage: water pollution is the

addition of any material or any change in character or quality of a water that

interferes with, lessens, or destroys a desired use.

Lee (1972) reported that oligotrophic lakes contain small amounts of

organisms but many different species of aquatic plants and animals. Eutrophic

lakes are generally though to contain large numbers of aquatic plants and

animals of a few species. Normally, lakes that are sufficiently deep to develop

a thermo cline ( two-layer system due to density differences as a result of the

thermal structure) and show a particle or complete depletion of dissolved

oxygen in the hypolimnion (bottom layer) are classified as eutuophic, while

those that maintain the oxygen in the hypolinmion throughout the period of

thermal stratification are oligotrophic. This oxygen depends on amounts of

aquatic plants that develop in the surface water and the morphology of the lake.

For lakes with a given amount of aquatic plant production in the eplimnion

(surface layers), those with a large hypolimnetic volume tend to have the

oxygen concentration depleted to a lesser degree than those with a small

hypolemnetic volume. With few exceptions, the amount of aquatic plants

produced in a lake is restricted to the surface waters since light penetration is

usually restricted to eplimnetic waters.

EPA (1990) reported that rapid changes in lake nutrient status and

productivity are often a result of human included disturbances to the watershed

rather than gradual enrichment and filling of the lake basin through natural

means. Human-induced cultural eutrophication occurs when nutrient, soil, or

organic matter loads to the lake are dramatically increased. A lake's lifespan

can be shortened drastically increased by activities such as forest clearing, road

building, cultivation, residential development, and wastewater treatment

discharges because these activities increase soil and nutrient loads that

eventually move into the lake. Natural and man-made lakes undergo

eutrophicaton by the same processes-nutrient enrichment and basin filling-but

at very different rates.

7

Michaud (1994) described that a larger fraction of the water in a

shallow lake is influenced by sunlight, and that photosynthesis and growth are

proportionately higher than in a deep lake.

Michaud (1994) also described unlike deep lakes, shallow lakes tend not

to stratify and are more likely to be mixed the same from top to bottom.

Anson (1997) stated water pollution is commonly defined as any

physical, chemical of biological change in water quality which adversely

impacts on living organisms in the environment or which makes a water

resource unsuitable for one or more of its beneficial uses. Some of the major

categories of beneficial uses of water resources include: public water supply,

irrigation, recreation, industrial production and nature conservation.

Moss (1998) reported the water is well mixed by wind, and physical

characteristics such as temperature and oxygen vary little with depth. Because

sunlight reaches all the way to the lake bottom, photosynthesis and growth

occur throughout the water column.

Simba (2001) described there are many dissolved substances in water

such as mineral salts, organic compounds (products of aquatic animals and

plants) etc. Some of these dissolved particles are electrically changed (ions).

These dissolved ions can provide the trace elements needed by aquatic plants.

Moss (2004) reported that the demand for surface water for many

purposes is increasing globally, mainly due to population growth and irrigation,

particularly in arid and semi-arid regions. Eutrophication often becomes

apparent to the public as populations increase in density. The total impact of

humans on nature is probably about high times higher today than 40-50 years

ago, given the growth in population, in industrial and agricultural production,

and in technological development (we use more chemicals, traffic density has

increased, etc.).

8

2.2 Eutrophication

Cable (1966) made a survey especially dense concentration of a single

species of zooplankton or phytoplankton are population explosions knows as

swarms, and flower or blooms. They occur seasonally or at irregular intervals

when environmental conditions are exceptionally favorable for the growth and

reproduction of a particular species. Swarming or flowering communities occur

most often when the water is enriched by runoff from agricultural land, by

upwelling from the bottom, by overturn of a body of water due to wind and

thermal changes, or by the addition of small quantities of organic wastes from

urban communities. Extensive investigations have shown that a great

preponderance of the basic or primary nutriment in the aquatic environment is

manufactured by the unicellular microscopic algae in the phytoplankton. These

tiny plants contain chloroplasts that can produce carbohydrates from carbon

dioxide and water in the presence of light (a process called photosynthesis).The

plant cells then synthesize complex organic compounds from suitable salts of

essential ignoring substances - - chiefly carbon, phosphorus, and nitrogen.

Waters that receive domestic and industrial wastes containing large amounts of

nitrogen and phosphorus compounds often nourish heavy growths of algae

Cairns, Albaugh, Bursey and Chaney (1968) were carried out

overloading with nitrogen and phosphorus can result in a series of undesirable

effects. Excessive growth of plankton algae increases the amount of organic

matter settling to the bottom. This may be enhanced by changes in the species

composition and functioning of the pelagic food web by stimulating the growth

of small flagellates rather than larger diatoms, which leads to lower grazing by

copepods in increased sedimentation. Diatoms can be used as an indicator for

water pollution. Because diatoms (single-celled algae) have frequently been

used to evaluate the impact of domestic sewage or industrial waste on the

aquatic environment. Use of these organisms in pollution impact evaluation is

justified by reason of their sensitive to pollutions. In a non-polluted

environment then will usually be a very high diversity of kinds of different

9

diatoms, while a polluted environment will show a very low diversity with only

a few different kinds of diatoms.

Vollenweider (1968) stated that especially implicated as specific

nutrients are nitrates and phosphates, anions which in nature are frequently

present in limiting amounts. Others which also probably play apart include

potassium, magnesium, sulphate, trace elements (cobolt, molybdenum, copper,

zinc, boron, iron, manganese, etc.), and organic growth factors.

National Academy of Sciences (1969) published remedial measures for

eutuophication centre upon the principal of limiting nutrient inflow

(particularly of nitrates and phosphates), removing nutrients already present in

the lake, and mechanically or chemically ridding the lake of nuisance plants by

cutting or poisoning. These practices are now widely used in the United States

and elsewhere; removal procedures usually involve chemical coagulation of

one sort or another. Phosphates can now be fairly easily removed, but nitrates

prove more difficult or complete distillation is resorted to in order to remove

nutrients.

Lee (1972) made a surveyed the eutrophication-exesssive fertilization of

natural waters is becoming one of the most important causes of water quality

deterioration. The cultural activities of man greatly accelerate the transport of

phosphorus, nitrogen and other elements which may limit aquatic plant growth

in natural waters. These nutrients stimulate the growth of floating or suspended

algae, attached algae and macrophytes. Excessive growths of these aquatic

plants result in a significant deterioration in water quality for the use of the

water for domestic and industrial water supplies, irrigation and recreation.

Bayly and Willians (1973) published there are several human activities

that may have considerable impact upon the inland aquatic environment but

which do not involve direct physical alteration to inland waters. The principal

effect of land-clearing (deforestation), over-grazing by stock, certain sorts of

agricultural malpractices, burning-off, and uncontrolled fires is to change the

pattern of run-off on drainage basin and hence alter the nature of fluctuation in

10

lake levels and rivers and stream flows. Invariably the trend is for such

fluctuations to become more extreme.

The transference by man, accidental or otherwise, of many species of

aquatic biota from one water body to another is also a human activity that has

affected the nature of inland waters and their biota. Such transference had

occurred on a global scale. On the other hand, much transference has had

deleterious results for mankind. Irrespective of the advantages or disadvantages

to man their total impact upon inland waters and biota ranges from an

apparently insignificant one to one that is highly significant.

Anonymous, 1976; Foge, 1965; Goldman, 1966; Manchenthum, 1965;

Manchenthum and Ingram, 1966; MIddlebrooks, Maloney, Powers and Kaack

(1969); and Vollenweider, 1969 was carried out of factors thus for considered,

if light, temperature, basin morphology and residence time of water are

"normal", a sufficiently high flux of aquatic plant nutrients can create

eutrophication problems. Even if these other factors are not "normal", i.e., they

are operating to increase aquatic plant production. This production is still most

frequently controlled by the flux of chemical compounds that influence algal

growth. Although the nutritional requirements of algae and higher aquatic

plants are poorly understood, it is generally agreed that they all have large

requirements for carbon (C), nitrogen (N), hydrogen (H), oxygen (O), and

phosphorus (P) and need lesser amounts of many different trace elements. The

nutrient requirements of aquatic plants except for the need for potassium by

terrestrial plants. The fixation of potassium by clay minerals causes a

deficiency in soils, while in water there is generally sufficient potassium to

meet the needs of the aquatic plants. Aquatic plants are different in one

important respect from some terrestrial plants in that they can use either NO3-

or NH4+ in preference to NO3

-. Some algae will take up NH4+ in preference to

NO3-. Some of the blue green algae also have the ability to grow at a very low

NO3- and NH4

+ concentration. Orthophosphate (PO4) is the form of phosphorus

11

that is readily available for algal growth although it is possible that other forms

such as P-O-P and organic phosphorus may also be available to algae.

Nixon (1995) stated that eutrophication refers to an increase in the rate

of supply of organic matter to an ecosystem, which most commonly is related

to nutrient enrichment enhancing the primary production in the system

In 2001 the UNEP-IETC/ILEC published eutrophication is one of the

most widespread environmental problems of inland waters, and is their

unnatural environment with two plant nutrients, phosphorus and nitrogen. In

many lakes and reservoirs in the world plants growing in the surface during

spring and summer will die during autumn and sink to the bottom where they

decompose.

Eutrophication is a process by which a water body progresses from its

origin to its extinction. During this period, there is a gradual accumulation of

nutrients and organic biomass, accompanied by a decrease in average depth of

the water due to the sediment accumulation, and an increase in primary

productivity, usually in the form of dense algal blooms. Cultural eutrophication

occurs when humans, through there various activities, greatly accelerate this

process. Eutrophication can cause loss in species diversity, fish kills, and

decrease the aesthetic value of a water body (Das, 2003).

Moss (2004) made a survey that eutrophication poses a great threat to

the recreational potential of lakes due to the health effects associated with toxic

algal blooms. Increased nutrient loading can stimulate algal growth.

TDS (350 mg L-1 to 180 mg L-1) levels were found in Inle Lake. EC

ranged between 20 μs cm-1 to 50 μs cm-1. Alkality was between 100 ppm > 200

ppm. pH was 758 to 8.88. Nitreates ranged from mostly not detected to 2.52

ppm at Myaynigone village. Phosphates ranged 0.03 to 1.34 ppm. Arsenic

found in Tale-U stream in rainy season. Dissolved oxygen was from 4.2 to 8.2

mg L-1 depending on sampling water layer. COD ranged from 4 mg L-1 to

54 mg L-1 depending on sampling layer and site. Total coliform count ranged

12

from 918 MPN/100 mL to > 2400 MPN/100 mL and was much higher than

WHO standard (200 MPN/100 mL) for drinking water.

Turbidity, COD and total coliform count changed with reason. DO

slightly varied and low where dense algae growth occurred in some parts of the

lake. In addition, electrical conductivity, COD and total coliform count were

above the WHO standards for drinking water. Inle Lake is in the initial phase

of eutrophication.

TDS and COD and alkalinity; and temperature and coliform, turbidity

and conductivity have correlationships. Sedimentation was found to be the

greatest thread to Inle Lake (May, 2007).

2.3 Previous Inle Condition

The lake is in the great Limeston Zone of the Shan Plateau. An

enormous amount of peaty matter is always formed around the Inle Lake in

condition with silt deposition from the inflowing steams and chaungs.

Inle is a solution lake type with its basin hollowed out of limestone by

the dissolving action of water. No 'sink' exists in the lake. It might have been

over hundred mites long and several hundred feet deep. The decay of

vegetation rendered the waters acid which ate through limestone rocks leading

to drainage of the Inle Lake.

Fauna of the Inle is a very highly specialized one, isolated for a

considerable time and evolution has taken place rapidly. Inle fauna is

remarkably rich in fish and molluscs, abundant in species and individuals

including endemic forms. Most fish have large eyes but lack barbels. Lower

vertebrates are poorly represented. Crustaceans are scarce. Among insects,

Odenata, Diptera and Rhynchota occurred but beetles are scarce. The aquatic

and quasi-aquatic fauna of the Inle district as a whole was separated from the

common fauna of the Oriented Region at not an extremely remote period

(Annandale, 1918).

13

2.4 Recent Inle condition

Flora and fauna species are diverse and enriched. It is a nesting place of

globally endangered Sarus Crane (Grus antigone). It has nine endemic fish

species with Inle Carp (Cyprinus carpio Intha) is locally well know food

resource. Inle is not only designated as 190th World's Eco-region but also as the

freshwater biodiversity hotspot by the World Conservatoin Monitoring Center

(WCMC, 1998).

Hydrophonic agriculture, using floating islands of peat formed by

decayed grasses, reeds, marsh plants entangled with bog mosses and algae, is

practiced by local ethnic Intha people in Inle Lake which is now a major

tomato production area supplying the whole country.

Combining with domestic effluent and increased use of fertilizer in

floating gardens, sedimentation results in the increases of nutrient uploading in

the lake leading to eutrophication process in Inle Lake. The Inle was 23

kilometers (km) long and 11 meters (m) wide in 1967 is now shrunk 11 km

long and 5 km wide in 1996 (Myanmar EPA, 2001).

Chan, Davies, Sebastian, Htay, Aye, Aung, Thwin and Shwe (2001)

assessed the Inle Lake condition and reported 18 endemic fish species in the

lake. Ten species were non-endemics but 8 species were introduced or of

uncertain status. Conductivity was 260 – 410 μs cm-1, DO 1.7 - 10.3 mg L-1, pH

7.6 - 8.3.

Natural nitrates, phosphates were rich in floating gardens where super

phosphate fertilizer as well as insecticides and fungicides were also applied for

tomato production in Inle (Elliott and Win 1993).

14

CHAPTER 3 MATERIALS AND METHODS

3.1 Study area

Inle Lake, located on the Shan plateau in the Southern Shan State of east

Myanmar and in Thanlwin river basin, was the study area. The geopositional

coordinates are N 20˚39.573'; E96˚55.136' (Fig. 3.1).

3.2 Study sites

Study sites were chosen based on human settlement, agricultural

activity, entry of major inflow (sedimentation), nearess to motorboat pathway

(oil spill), and approximity to center of lake (stagnant water).

Six study sites at different locations, Kyezagone village (only human

settlement), Lethit village (only cultivated agricultural gardens or floating

farms or floating islands), Mwepwe village (on the motorboat pathway to

Phaungdaw Oo Pagoda), Kela village (mixed human settlement and floating

islands), Innle (center of lake), Namlit- chaung* (entry of major inflow) were

designated to collect the water samples (Fig. 3.2).

*Chaung = stream

3.3 Study period

This study was conducted from March 2006 to January 2007.

15

Fig. 3.1. Map of study area (Source: Geography Department, University of Yangon)

16

Fig.3.2. Six study sites of Inle Lake, (A) Kyezogone, (B) Lethit, (C) Mwepwe,

(D) Kela, (E) Centre of lake and (F) Namlit-chaung

17

3.4 Materials

3.4.1 Equipment, apparatus and test kits

Most water quality parameters were measured by water quality test kits,

water quality test meters, strips and test tubes. Water temperature (T°C),

electrical conductivity(EC), total dissolved solid (TDS) and pH were measured

by MODEL 370 pH/m V meter made in The EU. Hardness, chloride (Cl),

fluoride (F) and Nitrate (NO3-N) were measured by WATSAN WAGTECH

Photometer 5000 Sr. No 5 to 8 potable test kit made in The EU, with hardicol

reagent tablets No. 1 and 2; acidifying CD chloridol reagent tablets; fluoride

reagent tablets No. 1 and 2; nitratest tablets/ nitratest powder and nitricol

tablets respectively. Turbidity analysis was used to turbidity test tube. Arsenic

analysis was done by Arsenic analytical test strips with reagent 1 and 2 made

by Merck KGaA, 64271 Darmstadt, Germany. Phosphate analysis was done by

Spectrophotometer at Tharkayta freshwater Aquaculture Research Chemical

Laboratory. Dissolved oxygen (DO) was measured in the field by DO test kit

with reagents 1, 2, 3, 4 of Annawamon Co. Ltd., Tharkayta. Biochemical

oxygen demand (BOD) analysis was done by Winkler titration method at the

Tharkayta Chemical Lab. Water depths were measured by marked poles in

each study site.

3.5 Methods

Sampling frequency for eutrophication: 12 per year, including twice

monthly during the summer for lakes or reservoirs (Bartran and Ballance

1996).

3.5.1 Collection of water samples

Water samples were collected from selected study sites to one liter

plastic bottles with caps. The samples were taken monthly in wet and cool

seasons and twice a month in the hot season. Collected water samples were

18

sent immediately to the laboratories of UNDP, Integrated Community

Development Project (ICDP), Nyaung Shwe Township, Southern Shan State

for most of physicochemical analysis.

3.5.2 Physicochemical analysis of water samples

Most water parameters consisting pH, water temperature (T˚C),

turbidity, Hardness, electrical conductivity (EC), total dissolved solid (TDS),

arsenic (As), chloride (Cl), fluoride (F) and nitrate (NO3-N) were analyzed of

the laboratory of UNDP, ICDP, Nyaung Shwe Township (Plate 3.1 and 3.2).

Detection of phosphate (PO4-P) and biochemical oxygen demand (BOD)

in the water samples was carried out in the laboratory of Freshwater

Aquaculture Research Department, Tharkayta Township, Yangon. Water depth

and dissolved oxygen (DO) were tested immediately in the field.

3.6 Data analysis

Statistical analyses were made by coefficient of correlation (R2) and

regression equation (Y = a X + b), where ‘a’ is the slopping degree and ‘b’ is

the intersection point. All data were conducted using graphic presentation was

by Excel programme.

19

(A) Kyezaygone village (B) Lethit village

(C) Mwepwe village (D) Kela village

(E) Centre of the lake (F) Namlit chaung

Plate 3.1. Collection sites of water samples showing different conditions

20

(A) Collecting water sample (B) MODEL 270 Ph/m V meter

(C) WATSAN WAGTECH Photometer (D)Arsenic test kit

(E) Phosphate test kit (F) Dissolved oxygen test kit

Plate 3.2. Collection of water samples and meters and test-kits

21

CHAPTER 4 RESULTS

4.1. Physical Parameters

4.1.1 Water depth

Water depths of Inle Lake were found to be changing with seasons in six

study sites. The deepest area 480 cm is the centre of lake at October measuring,

and the shallowest area is found to be 150 cm at Mwepwe village in June.

Based on the study sites, the highest water depth of 420 cm was

recorded in Kyezagone village in October while the minimum water depth of

157.5 cm was detected in June. Similarly, the maximum water depths 447.5

cm in Lethit village was observed in October and minimum water depth was at

157.5 cm in June. The maximum water depth 337.5 cm was found in October

at Mwepwe village and minimum water depth 150 cm in June. In Kela village,

the maximum water depth 360 cm was found in September and October while

the minimum water depth was 230 cm in June. In the centre of the lake the

maximum water depth 480 cm was observed in October and the minimum

water depth 210 cm was found in June. The maximum depth 470 cm in

October was observed at Namlit-chaung and the minimum 140 cm in June.

According to season, in Inle Lake the shallowest levels of water depth

were found in April, May, June, July while the moderate levels of water depth

were found in January, February, March and the deepest levels of water depth

were found in August, September, October, November and December. In all

study sites, maximum water depths were recorded in wet season while the

minimum water depths were found at the end of hot season and beginning of

wet season (Table 4.1 and Fig. 4.1).

Table 4.1. Monthly water depth (cm) at different water sampling sites during study period

Study site

2006 2007

Mar Apr I Apr II May I May II Jun Jul Aug Sep Oct Nov Dec Jan Feb

Kyezagone 187.50 182.50 165.00 162.50 162.50 157.50 187.50 227.50 297.50 420.00 285.00 262.50 240.00 230.00

Lethit 172.50 170.00 177.50 212.50 165.00 157.50 170.00 210.00 300.00 447.50 290.00 257.50 240.00 230.00

Mwepwe 180.00 170.00 160.00 167.50 155.00 150.00 162.50 202.50 217.50 337.50 222.50 215.00 210.00 200.00

Kela 275.00 270.00 205.00 257.50 235.00 230.00 242.50 282.50 360.00 360.00 355.00 295.00 300.00 290.00

Centre of lake 302.50 297.50 257.50 255.00 222.50 210.00 227.50 267.50 420.00 480.00 432.50 362.50 375.00 365.00

Namlit 185.00 172.50 225.00 207.50 145.00 140.00 150.00 190.00 342.50 470.00 402.50 335.00 340.00 320.00

22

Fig. 4.1. Monthly variation of water depth (cm) in six study sites (March 2006 to February 2007)

23

0

100

200

300

400

500

600M

ar-0

6

Apr

I-06

Apr

II-

06

May

I-06

May

II-

06

Jun-

06

Jul-0

6

Aug

-06

Sep-

06

Oct

-06

Nov

-06

Dec

-06

Jan-

07

Feb-

07

Wat

er d

epth

(cm

)

Year

Kyezagone Lethit Mwepwe Kela Centre of lake Namlit

24

4.1.2 Electrical conductivity

The ability of water to conduct an electric current is known as

conductivity or specific conductance and depends on the concentration of ions

in solution (Bartram and Ballance, 1996). The WHO standard guideline value

of electrical conductivity is 1500 μs cm-1.

Electrical conductivity (EC) level of the water of Inle Lake was

observed to be in random fluctuation. Maximum level of 481 μs cm-1 in March

and the minimum level of 42 μs cm-1 in October were recorded in Inle lake

throughout the year.

In Kyezagone, the highest level of EC was 411 μs cm-1 in first half of

April and lowest level of EC was 70.2 μs cm-1 in November. In Lethit village,

the highest level of EC was 348 us cm-1 in March and lowest level of EC was

42 μs cm-1 in October. In Mwepwe village, the highest level of EC was 382 μs

cm-1 in first half of April and lowest level of EC was 44 μs cm-1 in October. In

Kela village, the highest level of EC was 400 μs cm-1 in March and lowest level

of EC was 76.4 μs cm-1 in November. In the center of the lake, the highest level

of EC was 280 μs cm-1 in December and lowest level of EC was 60 μs cm-1 in

first half of May and October. In Namlit-chaung, the highest level of EC was

481 μs cm-1 in March and lowest level of EC was 67.9 μs cm-1in November

(Table 4.2 and Fig. 4.2).

4.1.3 Total Dissolved Solids

Total dissolved solids (TDS) can be determined simply by filtering a

water sample and evaporating a known volume of filtrate to dryness at 103°C

(Bayly and Williams, 1973).

The concentration of total dissolved solid (TDS) in Kyezagone village

was observed to be high in first half of April in 247 mg L-1 and low in

Table 4.2. Monthly electrical conductivity values (μs cm-1) at different water sampling sites during study period

Study site

2006 2007


Kyezagone 389.00 411.00 400.00 99.60 96.00 113.20 110.20 115.20 96.00 99.60 70.20 250.00 115.20 110.20

Lethit 348.00 328.00 331.00 84.80 89.70 109.40 90.50 100.40 89.70 42.00 66.30 320.00 100.40 90.50

Mwepwe 381.00 382.00 363.00 223.00 95.40 100.90 100.80 98.40 95.20 44.00 84.40 360.00 100.80 100.80

Kela 400.00 390.00 372.00 95.50 100.80 105.70 100.70 100.70 105.20 95.50 76.40 100.80 105.20 100.70

Centre of lake 234.00 231.00 223.00 60.00 61.80 64.80 69.60 68.80 61.80 60.00 81.50 280.00 69.60 69.60

Namlit 481.00 286.00 311.00 82.60 75.30 71.20 76.20 90.50 75.30 314.00 67.90 320.00 95.50 76.20

WHO standard guide line value of EC = 1500 μs cm-1

25

Fig. 4.2. Monthly variation of electrical conductivity (mg L -1) in six study sites (March 2006 to February 2007)

26

0

200

400

600M

ar-0

6

Apr

I-06

Apr

II-0

6

May

I-06

May

II-0

6

Jun-

06

Jul-0

6

Aug

-06

Sep-

06

Oct

-06

Nov

-06

Dec

-06

Jan-

07

Feb-

07

EC

(μs c

m-1

)

Year


27

42.2 mg L-1 in November. In Lethit village the highest level of TDS was 209 mg L-1 in March and the lowest level of TDS was 25 mg L-1 in October. In Mwepwe village the highest level of TDS was 229 mg L-1 in first half of April and the lowest level of TDS was 27 mg L-1 in October. In Kela village the highest level of TDS was 240 mg L-1 in March and the lowest level of TDS was 49.5 mg L-1 in November. In the center of lake the highest level of TDS was 140.9 mg L-1 in March and the lowest level of TDS was 36 mg L-1 in first half of May and October. In Namlit-chaung the highest level of TDS was 289 mg L-1 in March and the lowest level of TDS was 40.7 mg L-1 in November.

The highest levels of TDS in all study sites were found in hot season and the lowest levels of TDS in all study sites were found in cool season. In all study sites the highest level was 289 mg L-1 in March at Namlit-chaung and the lowest level was 25 mg L-1 in Lethit village in October (Table 4.3 and Fig. 4.3).

4.1.4 Turbidity

Turbidity is an expression of light penetration through water. The most reliable method of determination uses nephelometry (light scattering by suspended particles) by means of a turbidity meter which gives values in Nephelometric Turbidity Units (NTU) (Chapman, 1992).

In Inle Lake turbidity level was no more than 5 NTU in all six study sites. The WHO standard was 5 NTU.

4.1.5 Hardness

The hardness of natural water depends mainly on the presence of dissolved calcium and magnesium salts. The total content of these salts is known as general hardness, which can be further divided into carbonate hardness (determined by concentration of calcium and magnesium hydrocarbonates), and non-carbonate hardness (determined by calcium and magnesium salts of strong acids). Hydrocarbonates are transformed during the

Table 4.3. Monthly Total Dissolved Solids (mg L-1) at different water sampling sites during study period

Study site

2006 2007


Kyezagone 234.00 247.00 240.00 59.70 57.60 67.90 67.50 60.50 57.60 59.70 42.20 67.50 67.50 67.60

Lethit 209.00 196.80 198.70 50.90 53.90 65.60 66.50 53.90 53.90 25.00 39.70 200.00 66.50 66.50

Mwepwe 228.00 229.00 218.00 59.00 57.20 60.60 60.20 59.50 60.60 27.00 50.60 60.20 59.50 60.00

Kela 240.00 234.00 223.00 57.30 60.50 63.50 61.50 65.10 63.50 57.30 45.90 60.50 61.50 61.50

Centre of lake 140.90 138.70 133.90 36.00 37.10 38.80 40.10 39.80 38.80 36.00 49.40 40.10 39.80 40.00

Namlit 289.00 171.60 186.10 49.60 45.20 42.70 48.60 50.50 42.70 188.00 40.70 48.60 50.50 48.80

WHO standard guide line value of TDS = 1000 mg L-1

28

Fig. 4.3. Monthly variation of total dissolved solid (mg L -1) in six study sites (March 2006 to February 2007)

29

0

100

200

300

400M

ar-0

6

Apr

I-06

Apr

II-0

6

May

I-06

May

II-0

6

Jun-

06

Jul-0

6

Aug

-06

Sep-

06

Oct

-06

Nov

-06

Dec

-06

Jan-

07

Feb-

07

TD

S (m

g L

-1)

Year


30

boiling of water into carbonates, which usually precipitate. Therefore,

carbonate hardness is also known as temporary or removed, whereas the

hardness remaining in the water after boiling is called constant (Chapman,

1992).

The hardness of the water of Inle Lake was observed to be in random

fluctuation. The highest level of hardness 210 mg L-1 were found in the second

half of April and December in Kyezagone village and first half of April in Kela

village. The lowest level 44 mg L-1 was found at Lethit village in October.

Based on the study sites, the highest level 210 mg L-1 was recorded in

the second half of April and December while the lowest level 130 mg L-1 in

November at Kyezagone village. At Lethit village the highest level 195 mg L-1

was found in June and February and the lowest level 44 mg L-1 in October. In

Mwepwe village the highest level 185 mg L-1 was found in first half of May

and the lowest level 48 mg L-1 in October. At Kela village the highest level 210

mg L-1 was found in first half of April and the lowest level 115 mg L-1 in

November. In the centre of the lake, the highest level 155 mg L-1 was found in

July, January and February and the lowest level 90 mg L-1 in second half of

April and December. In Namlit-chaung the highest level 195 mg L-1 was found

in October and the lowest level 90 mg L-1 in July (Table 4.4 and Fig. 4.4).

4.1.6 Water temperature

Water is a very poor conductor of heat. Heat circulation of water is

usually done by convection: warmer water moves upwards and cooler water

moves downwards. Temperature plays an important role in the aquatic

environment in that certain organisms, including fish, are sensitive to water

temperatures (Chan, 1999).

In Inle Lake, the lowest temperature 17.9˚C was found at Lethit village

in November, and the highest temperature 28.6˚C at Mwepwe village and

centre of lake in February and August, and second half of May respectively.

Table 4.4. Monthly hardness (mg L-1) at different water sampling sites during study period

Study site

2006 2007


Kyezagone 175.00 155.00 210.00 165.00 195.00 145.00 155.00 175.00 145.00 165.00 130.00 210.00 145.00 175.00

Lethit 165.00 130.00 155.00 137.00 155.00 195.00 185.00 155.00 195.00 44.00 95.00 165.00 185.00 195.00

Mwepwe 137.00 185.00 155.00 155.00 155.00 155.00 102.00 165.00 102.00 48.00 155.00 108.00 102.00 102.00

Kela 145.00 210.00 165.00 165.00 165.00 155.00 165.00 165.00 155.00 165.00 115.00 155.00 165.00 165.00

Centre of lake 95.00 108.00 90.00 108.00 95.00 95.00 155.00 102.00 95.00 108.00 145.00 90.00 155.00 155.00

Namlit 155.00 137.00 122.00 137.00 130.00 95.00 90.00 95.00 95.00 195.00 115.00 140.00 95.00 95.00

WHO standard guide line value of hardness = 500 mg L-1

31

Fig. 4.4. Monthly variation of hardness (mg L-1) in six study sites (March 2006 to February 2007)

32

0

50

100

150

200

250

Mar

-06

Apr

I-06

Apr

II-0

6

May

I-06

May

II-0

6

Jun-

06

Jul-0

6

Aug

-06

Sep-

06

Oct

-06

Nov

-06

Dec

-06

Jan-

07

Feb-

07

Har

dnes

s (m

g L

-1)

Year


33

According to study sites, the highest water temperature 28˚C at

Kyezagone village was found in second half of May, August, December and

February while the lowest water temperature 19.9˚C was found in November.

The highest water temperature 28˚C at Lethit village was found in March while

the lowest water temperature 17.9˚C was found in November. The highest

water temperature 28.6˚C at Mwepwe village was found in February while the

lowest water temperature 19.3˚C was found in November. The highest water

temperature 28.1˚C at Kela village was found in August, September and

February while the lowest water temperature 18.1˚C was found in November.

The highest water temperature 28.6˚C in the centre of lake was found in second

half of May while the lowest water temperature 18.3˚C was found in

November. The highest water temperature 28˚C in Namlit-chaung was found in

March and October while the lowest water temperature 18.2˚C was found in

November.

In Inle Lake the annual water temperature ranged from 15˚C to 29˚C.

Overall results showed that the lowest water temperature among the six study

sites was found in November. The highest water temperatures were randomly

fluctuating in the lake throughout the year (Table 4.5 and Fig. 4.5).

4.2 Chemical Parameters

The chemical parameters include levels of arsenic (As), chloride (-Cl),

fluoride (-F), pH, dissolved oxygen (DO), and biochemical oxygen demand

(BOD).

4.2.1 Arsenic

Arsenic is able to accumulate in large quantities in the sediments on the

bed of water courses and reservoirs, and in aquatic organisms (Svobodovaet al.,

1993).

Arsenic was not detected in all study sites throughout the study period.

Table 4.5. Monthly water temperature (°C) at different water sampling sites during study period

Study site

2006 2007


Kyezagone 27.80 27.30 23.70 24.80 28.00 27.20 27.20 28.00 27.20 24.80 19.90 28.00 27.20 28.00

Lethit 28.00 26.80 23.90 24.60 27.30 27.20 27.30 26.10 27.30 21.40 17.90 23.30 27.30 26.10

Mwepwe 27.80 26.50 23.50 24.20 28.40 27.60 27.30 28.60 27.60 22.50 19.30 24.20 27.60 28.60

Kela 27.70 25.70 23.70 24.70 28.00 27.10 28.00 28.10 28.10 24.70 18.10 26.00 28.10 28.10

Centre of lake 27.50 25.20 23.50 24.70 28.60 27.40 27.40 28.40 28.40 28.00 18.30 24.80 28.40 28.40

Namlit 28.00 24.70 23.30 24.70 20.50 27.40 27.60 27.40 27.60 28.00 18.20 23.30 27.60 27.60

WHO standard guide line value of water temperature = 0°C - 30°C

34

Fig. 4.5. Monthly variation of temperature (�C) in six study sites (March 2006 to February 2007)

35

0

5

10

15

20

25

30

35M

ar-0

6

Apr

I-06

Apr

II-0

6

May

I-06

May

II-0

6

Jun-

06

Jul-0

6

Aug

-06

Sep-

06

Oct

-06

Nov

-06

Dec

-06

Jan-

07

Feb-

07

Tem

pera

ture

(°C

)

Year


36

4.2.2 Chloride

Chlorine is an interesting atmospheric pollutant. Active chlorine is very

toxic to fish. Active chlorine may affect the specific parts of the fish (eg. the

skin and gills) of the whole body (i.e. when chlorine is absorbed into the blood)

(Svobodova et al., 1993). Most chlorines occur as chloride (Cl-) in solution.

Chlorides occur in all natural water in widely varying concentration. Human

excreta, particularly in the urine, contain chlorides consumed with food and

water. This amount averages about 6 g of chloride per person per day increases

the amount of Cl- in sewage about 15 mg L-1 above that of the carriage water.

Thus sewage effluents and considerable chlorides to receiving streams. Many

industrial waters contained appreciable amounts of chlorides (Environmental

Engineering Laboratory, Department of Civil Engineering, Yangon Institute of

Technology).

Chloride level of the water of Inle Lake was observed to be randomly

fluctuated. In Kyezagone village, the highest level of chloride was 260

mg L-1 in first half of May and October. The lowest level was 16 mg L-1 in June

and September. At Lethit, the highest level of chloride was 205 mg L-1 in June

and lowest level 10 mg L-1 in November. At Mwepwe village, the highest level

was 82 mg L-1 in October and lowest level was 0 mg L-1 in first half of April.

At Kela village the highest level was 106 mg L-1 in November and lowest level

was 0 mg L-1 in first half of May and October. In the center of lake the highest

level was 80 mg L-1 in October and lowest level was 25 mg L-1 December. In

Namlit-chaung the highest level was 36 mg L-1 November and the lowest level

was 7 mg L-1 in the second half of May. In all six study sites the highest level

of chlorides was 260 mg L-1 and lowest level was 0 mg L-1 (Table 4.6 and

Fig. 4.6).

4.2.3 Fluoride

Fluoride is used in certain industrial process and consequently occurs in

the resulting waste waters. Significant industrial sources of fluoride are the

Table 4.6. Monthly chlorides (mg L-1) at different water sampling sites during study period

Study site

2006 2007


Kyezagone 26.00 60.00 28.00 260.00 30.00 16.00 22.00 25.00 16.00 260.00 85.00 27.00 25.00 25.00

Lethit 26.00 32.00 22.00 36.00 115.00 205.00 118.00 115.00 115.00 95.00 10.00 200.00 118.00 118.00

Mwepwe 32.00 0.00 7.00 45.00 23.00 28.00 27.00 27.00 23.00 82.00 7.00 70.00 27.00 27.00

Kela 28.00 35.50 58.00 0.00 25.00 16.00 27.00 22.00 16.00 0.00 106.00 20.00 27.00 27.00

Centre of lake 44.00 27.00 41.00 30.00 76.00 44.00 70.00 76.00 76.00 80.00 36.00 25.00 76.00 76.00

Namlit 30.00 16.00 27.00 23.00 7.00 25.00 25.00 25.00 27.00 72.00 36.00 22.00 25.00 27.00

WHO standard guide line value of chlorides = 200 - 600 mg L-1

37

Fig. 4.6. Monthly variation of chloride (mg L-1) in six study sites (March 2006 to February 2007)

38

0

50

100

150

200

250

300

Mar

-06

Apr

I-06

Apr

II-0

6

May

I-06

May

II-0

6

Jun-

06

Jul-0

6

Aug

-06

Sep-

06

Oct

-06

Nov

-06

Dec

-06

Jan-

07

Feb-

07

Chl

orid

es (

mg

L-1

)

Year


39

production of coke, glass and ceramics, electronics, steel and aluminium

processing, pesticides and fertilizers, and electroplating operations. Waste

levels may range from several hundred to several thousand milligrams per litre

in untreated waste water. It is worthy of note that conventional treatment (lime)

seldom reduces fluoride concentration below 8 to 15 mg L-1 without dilution

(Bartram and Ballance 1996).

The content of fluoride in Inle Lake was different from place to place.

The maximum content of fluoride at Kyezagone village was 1.15 mg L-1 in

February and minimum was 0.25 mg L-1 in December. The maximum value at

Lethit village was 0.85 mg L-1 in February and minimum value was 0.25

mg L-1 in October. The maximum value at Mwepwe village was 1.15 mg L-1 in

March and minimum value of fluoride was 0 mg L-1 in first half of April. The

maximum value at Kela village was 0.95 mg L-1 in February and minimum

value was 0.2 mg L-1 in March. The maximum value in the centre of lake was

0.95 mg L-1 in November and minimum value was 0.2 mg L-1 in February. The

maximum value in Namlit-chaung was 0.85 mg L-1 in March and minimum

value was 0.1 mg L-1 in October (Table 4.7 and Fig. 4.7).

4.2.4 Water pH

The pH is a measure of the acid balance of a solution and is defined as

the negative of the logarithm to the base 10 of the hydrogen ion concentration.

The pH scale runs from 0 - 14 (i.e. very acidic to very alkaline), with pH 7

representing a neutral condition (Chapman, 1992).

At Kyezagone village the maximum value of pH 8 was observed in

September and December while the minimum value of pH 7.14 was detected in

March and first half of April. Similarly, the maximum value of pH 7.88 at

Lethit village was found in July and minimum value of pH was 6.64 in

October. The maximum value of pH 7.91 at Mwepwe village was observed in

second half of May and December and minimum value of pH was 6.8 in

October. The maximum value of pH 8 at Kela village was examined in January

Table 4.7. Monthly fluoride (mg L-1) at different water sampling sites during study period

Study site

2006 2007


Kyezagone 0.95 0.70 0.70 0.60 0.30 0.40 0.30 0.40 0.30 0.60 0.50 0.25 0.30 1.15

Lethit 0.60 0.65 0.75 0.40 0.40 0.75 0.40 0.75 0.40 0.25 0.60 0.30 0.75 0.85

Mwepwe 1.15 0.00 0.40 0.50 0.20 0.50 0.50 0.50 0.20 0.22 0.55 0.50 0.50 0.55

Kela 0.20 0.55 0.35 0.55 0.35 0.50 0.25 0.60 0.50 0.55 0.70 0.50 0.25 0.95

Centre of lake 0.55 0.35 0.40 0.60 0.30 0.75 0.65 0.75 0.75 0.60 0.95 0.65 0.75 0.20

Namlit 0.85 0.55 0.80 0.35 0.35 0.80 0.35 0.60 0.17 0.10 0.60 0.65 0.80 0.80

WHO standard guide line value of fluoride = 1.5 mg L-1

40

Fig. 4.7. Monthly variation of fluoride (mg L-1) in six study sites (March 2006 to February 2007)

41

0

0.2

0.4

0.6

0.8

1

1.2

1.4

Mar

-06

Apr

I-06

Apr

II-0

6

May

I-06

May

II-0

6

Jun-

06

Jul-0

6

Aug

-06

Sep-

06

Oct

-06

Nov

-06

Dec

-06

Jan-

07

Feb-

07

Fluo

ride

(mg

L-1

)

Year


42

and minimum value of pH was 7 in October. The maximum value of pH 8.92

in the centre of lake occurred in June and minimum value of pH was 7 in

October. The maximum value of pH 8.13 in Namlit-chaung was noted in

August and minimum value of pH was 6.54 in March. In all six study sites the

minimum value of pH was found in October (Table 4.8 and Fig. 4.8).

4.2.5 Dissolved Oxygen

Dissolved oxygen (DO) is necessary for the life of fish and other aquatic

organisms. The DO concentration may also be associated with corrosivity of

water, photosynthetic activity and septicity. The oxygen content of surface

water is usually high because of the solution of gas from the atmosphere

(Chapman, 1992).

The maximum concentration level of dissolved oxygen (DO) was 19.5

mg L-1 and minimum concentration level was 2 mg L-1 among six study sites.

At Kyezagone village, the maximum level of DO was 7.75 mg L-1in second

half of May and minimum level of DO was 2 mg L-1 in October. At Lethit

village the maximum level of DO was 12.75 mg L-1 in second half of May and

minimum concentration of DO was 2.25 mg L-1 in December. At Mwepwe

village the maximum level of DO was 12 mg L-1 in second half of May and

minimum level of DO was 2.5 mg L-1 in November. At Kela village the

maximum level of DO was 5.57 mg L-1 in second half of May and minimum

level of DO was 2.75 mg L-1 in August and December. In the center of the lake

the maximum level of DO was 19.5 mg L-1 in September and minimum level of

DO was 3 mg L-1 in second half of April. In all study sites, maximum levels

were recorded in the dry season especially in May while the minimum levels

were found random fluctuation during the rest of the year (Table 4.9 and

Fig. 4.9).

Table 4.8. Monthly pH values at different water sampling sites during study period

Study site

2006 2007


Kyezagone 7.14 7.14 7.37 7.31 7.35 7.49 7.50 7.50 8.00 7.31 7.54 8.00 7.31 7.63

Lethit 7.70 7.71 7.66 7.33 7.70 7.86 7.88 7.80 7.00 6.64 6.72 7.00 7.50 7.38

Mwepwe 7.52 7.10 7.68 7.63 7.91 7.81 7.71 7.80 7.50 6.80 7.00 7.91 7.66 7.63

Kela 7.23 7.13 7.38 7.35 7.54 7.53 7.50 7.60 7.40 7.00 7.16 7.50 8.00 7.70

Centre of lake 8.16 7.80 8.00 8.38 8.62 8.92 8.62 8.40 8.00 7.00 7.62 8.52 8.38 8.55

Namlit 6.54 7.85 7.10 7.60 8.00 8.00 8.00 8.13 8.00 7.04 7.86 8.00 7.37 8.00

WHO standard guide line value of pH value = 6.5 - 9.5

43

Fig. 4.8. Monthly variation of water pH values in six study sites (March 2006 to February 2007)

44

0

1

2

3

4

5

6

7

8

9

10

Mar

-06

Apr

I-06

Apr

II-0

6

May

I-06

May

II-0

6

Jun-

06

Jul-0

6

Aug

-06

Sep-

06

Oct

-06

Nov

-06

Dec

-06

Jan-

07

Feb-

07

pH v

alue

Year


Table 4.9. Monthly dissolved oxygen (DO) (mg L-1) at different water sampling sites during study period

Study site

2006 2007


Kyezagone 3.50 3.50 2.50 4.00 7.75 4.00 3.00 4.00 2.75 2.00 4.25 3.25 2.50 3.75

Lethit 3.50 3.50 3.50 4.00 12.75 11.25 6.00 5.25 7.50 5.50 2.50 2.25 5.25 3.50

Mwepwe 3.20 3.50 3.00 4.50 12.00 7.00 8.00 3.50 4.25 3.50 2.50 3.00 7.00 3.00

Kela 3.00 3.20 3.50 3.50 5.57 4.25 4.00 2.75 3.00 3.50 3.00 2.75 3.00 4.00

Centre of lake 3.50 3.00 3.00 3.50 14.55 11.25 7.00 10.00 11.50 10.50 6.75 6.75 7.00 8.00

Namlit 3.20 3.50 3.00 4.00 15.25 10.25 9.50 16.75 19.50 7.00 11.75 10.25 11.00 8.50

WHO standard guide line value of DO = 4.0 mg L-1

45

Fig. 4.9. Monthly variation of dissolved oxygen (mg L-1) in six study sites (March 2006 to February 2007)

46

0

5

10

15

20

25

Mar

-06

Apr

I-06

Apr

II-0

6

May

I-06

May

II-0

6

Jun-

06

Jul-0

6

Aug

-06

Sep-

06

Oct

-06

Nov

-06

Dec

-06

Jan-

07

Feb-

07

DO

(mg

L-1

)

Year


47

4.2.6 Biochemical Oxygen Demand

Biochemical oxygen demand (BOD) can be defined as the quantity of

oxygen utilised by a mixed population of micro-organisms in the aerobic

oxidation at temperature of 20°C and incubation period of 5 days

(Environmental Engineering Laboratory, Department of Civil Engineering,

Yangon Institute of Technology).

The maximum level 3 mg L-1 of biochemical oxygen demand (BOD) in

February at Namlit-chaung and minimum level 0.25 mg L-1 in December at

Lethit village were observed in Inle Lake.

At Kyezagone village, maximum level was 2.5 mg L-1 in December and

minimum level was 0.5 mg L-1 in June and July. At Lethit village, maximum

level was 2.5 mg L-1 in second half of April and minimum level was 0.25 mg

L-1 in December. At Mwepwe village, maximum level was 2.5 mg L-1 in March

and minimum level was 0.95 mg L-1 in November. At Kela village maximum

level was 2 mg L-1 in March and December while the minimum level was

observed at 0.5 mg L-1 in June and July. In the center of the lake maximum

level was found to be 2.5 mg L-1 in December and minimum level was 1 mg L-1

in April, May, August, October and November respectively. In Namlit-chaung

maximum level was 3 mg L-1 in February and minimum level was 0.5 mg L-1 in

November (Table 4.10 and Fig. 4.10)

Table 4.10. Monthly biochemical oxygen demand (BOD) (mg L-1) at different water sampling sites during study period

Study site

2006 2007


Kyezagone 2.00 1.20 1.20 1.50 1.20 0.50 0.50 1.00 1.00 1.20 2.00 2.50 1.50 1.50

Lethit 2.20 1.80 2.50 1.50 1.50 2.00 1.00 0.50 1.50 1.50 1.05 0.25 1.00 1.00

Mwepwe 2.50 1.80 1.50 1.00 1.00 1.50 1.50 1.00 1.00 1.30 0.95 1.50 1.50 1.00

Kela 2.00 1.50 1.20 1.00 1.00 0.50 0.50 1.50 1.50 1.20 1.00 2.00 1.00 1.00

Centre of lake 2.00 1.20 1.00 1.00 1.00 1.50 1.50 1.00 1.20 1.00 1.00 2.50 2.00 1.40

Namlit 2.20 1.50 2.00 1.20 1.50 1.00 1.00 0.80 1.00 1.00 0.50 1.50 2.00 3.00

WHO standard guide line value of BOD = 3.0 mg L-1

48

Fig. 4.10. Monthly variation of biochemical oxygen demand (mg L-1) in six study sites (March 2006 to February 2007)

49

0

0.5

1

1.5

2

2.5

3

3.5M

ar-0

6

Apr

I-06

Apr

II-0

6

May

I-06

May

II-0

6

Jun-

06

Jul-0

6

Aug

-06

Sep-

06

Oct

-06

Nov

-06

Dec

-06

Jan-

07

Feb-

07

BO

D (m

g L

-1)

Year


50

4.3 Nutrient pollutants

The two nutrient pollutants of nitrates and phosphates were detected in

Inle lake water samples.

4.3.1 Nitrate-nitrogen (NO3-N)

Nitrates, the most highly oxidised form of nitrogen compounds, are

commonly present in surface and ground waters, because it is the end product

of the aerobic decomposition of organic nitrogenous matter. Significant sources

of nitrate are chemical fertilizers from cultivated land drainage from livestock

feedlots, as well as domestic and some industrial waters.

The concentration of nitrate nitrogen was in random fluctuation in all six

study sites. The maximum level 0.85 mg L-1 was found at Lethit village in

December and in the centre of the lake in August, January and February. The

minimum level was 0.01 mg L-1 at Kyezagone village in first half of April.

At Kyezagone village the maximum level was 0.55 mg L-1 in first half

of May and the minimum level was 0.01 mg L-1 in first half of April. At Lethit

village the maximum level was 0.85 mg L-1 in December and the minimum

level was 0.23 mg L-1 in first half of April. At Mwepwe village, the maximum

level was 0.60 mg L-1 in August and the minimum level was 0.03 mg L-1 in

first half of April. At Kela village the maximum level was 0.80 mg L-1 in

August and the minimum level was recorded 0.03 mg L-1 at March. In centre of

lake the maximum levels were 0.85 mg L-1 in August, January and February,

and in minimum levels were recorded 0.12 mg L-1 at first half of May and

October. In Namlit-chaung the maximum level was 0.50 mg L-1 in March and

August, and the minimum level was 0.03 mg L-1 in the second half of May

(Table 4.11 and Fig. 4.11).

Table 4.11. Monthly nitrates (mg L-1) at different water sampling sites during study period

Study site

2006 2007


Kyezagone 0.35 0.01 0.20 0.55 0.08 0.15 0.20 0.60 0.15 0.06 0.08 0.12 0.12 0.08

Lethit 0.26 0.23 0.27 0.28 0.47 0.31 0.47 0.75 0.31 0.27 0.38 0.85 0.75 0.38

Mwepwe 0.08 0.03 0.22 0.32 0.05 0.06 0.20 0.60 0.51 0.24 0.04 0.47 0.05 0.04

Kela 0.03 0.03 0.21 0.07 0.11 0.35 0.12 0.80 0.35 0.07 0.18 0.11 0.47 0.18

Centre of lake 0.32 0.28 0.31 0.12 0.17 0.17 0.20 0.85 0.17 0.12 0.43 0.37 0.85 0.85

Namlit 0.50 0.38 0.28 0.09 0.03 0.17 0.37 0.50 0.17 0.13 0.04 0.2 0.39 0.39

WHO standard guide line value of nitrates = 0.2 mg L-1

51

Fig. 4.11. Monthly variation of nitrate (mg L-1) in sample water of six study sites (March 2006 to February 2007)

52

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Mar

-06

Apr

I-06

Apr

II-0

6

May

I-06

May

II-0

6

Jun-

06

Jul-0

6

Aug

-06

Sep-

06

Oct

-06

Nov

-06

Dec

-06

Jan-

07

Feb-

07

Nitr

ates

(mg

L-1)

Year


53

4.3.2 Phosphate

In natural waters and waste waters, phosphorous occurs mostly as

dissolved orthophosphates and polyphosphates, and organically bound

phosphates (Chapman, 1992). Phosphorous is a constituent of a number of

classes of biologically important organic compounds including phospholipids,

nucleoproteins, sugar phosphates, DNA, ATP and ADP. In addition, inorganic

phosphate appears to act as an activator of some enzyme systems (Bayly and

Williams 1973).

Among the six study sites, the highest level of phosphate was 1 mg L-1

at Kela village in the second half of April and September and in the centre of

the lake in October. The lowest level in all six study sites was 0 mg L-1.

At Kyezagone village the highest level was 0.5 mg L-1 in the second half

of April, August, September and November while the lowest level of 0 mg L-1

was observed in first half of May, July, December, January and February. At

Lethit village, the highest level of 0.5 mg L-1 was observed in the second half

of April, September and October while the lowest level of 0 mg L-1 was

observed in May, July, August, December, January and February. At Mwepwe

village the highest level was 0.5 mg L-1 in the second half of April, August and

September while the lowest level was 0 mg L-1 in May, June, July, December,

January and February. At Kela village, the highest level was 1 mg L-1 in the

second half of April and September while the lowest level was 0 mg L-1 in

June, December, January and February. In the centre of the lake the highest

level was 1 mg L-1 in October while the lowest level was 0 mg L-1 in May,

June, July, August, December, January and February respectively. In Namlit-

chaung the highest level was 0.5 mg L-1 in the second half of April, September

and November while the lowest level was 0 mg L-1 in May, June, July, August,

October, December, January and February respectively (Table 4.12,

Fig. 4.12, Plate 4.1 and 4.2).

Table 4.12. Monthly phosphates (mg L-1) at different water sampling sites during study period

Study site

2006 2007


Kyezagone 0.10 0.15 0.50 0.00 0.01 0.10 0.00 0.50 0.50 0.10 0.50 0 0 0

Lethit 0.15 0.12 0.50 0.00 0.00 0.10 0.00 0.00 0.50 0.50 0.40 0 0 0

Mwepwe o.15 0.11 0.50 0.00 0.00 0.00 0.00 0.50 0.50 0.10 0.40 0 0 0

Kela 0.12 0.10 1.00 0.01 0.02 0.00 0.10 0.50 1.00 0.10 0.80 0 0 0

Centre of lake 0.12 0.12 0.50 0.00 0.00 0.00 0.00 0.00 0.50 1.00 0.50 0 0 0

Namlit 0.12 0.15 0.50 0.00 0.00 0.00 0.00 0.00 0.50 0.00 0.50 0 0 0

WHO standard guide line value of phosphates = 0.005 - 0.020 mg L-1

54

Fig. 4.12. Monthly variation of phosphate compound (mg L-1) in six study sites (March 2006 to February 2007)

55

0

0.5

1

1.5

Mar

-06

Apr

I-06

Apr

II-0

6

May

I-06

May

II-0

6

Jun-

06

Jul-0

6

Aug

-06

Sep-

06

Oct

-06

Nov

-06

Dec

-06

Jan-

07

Feb-

07

Phos

phat

es(m

g L

-1)

Year


56

(A) Fertilizer bags in tomato farm (B) Pesticides

(C) Spray fertilizer (folia) selling shop (D) Application of pesticides

(E) Domestic waste at Kela village(F) Human sewage disposed into the lake

Plate 4.1. Sources of nutrients and pollutants

57

(A) Algal bloom (B) Floating aquatic plant

(C) Mat of floating plants (D) Submerged algae

(E) Submerged aquatic plant (F) Decay of aquatic plant Plate 4.2. Different types of bloom of floating and submerged plants that

affect on the water quality of Inle lake

58

4.4 Correlation among water parameters in Inle lake

4.4.1 Physical parameters and water pH

Physical parameters of water temperature, hardness, total

dissolved solid and water pH were correlated with each others (Fig. 4.13 A, B,

and C).

Water temperature and pH value were positively correlated with the

correlation coefficient of R2 = 0.0683 and least squares regression of Y =

1.5872 X + 13.727 that indicates the two parameters were slightly correlated

(Table 4.13 and Fig. 4.13 A ).

Hardness and pH value were negatively correlated with the correlation

coefficient of R2 = 0.0407 and least squares regression of Y = -15.628 X +

260.6 that indicates the two parameters were highly correlated (Table 4.13 and

Fig. 4.13 B).

Total dissolved solids and pH values were negatively correlated with the

correlation coefficient of R2 = 0.1043 and least squares regression of Y = -

48.411 X + 459.56 that indicates the TDS and pH were significantly correlated

(Table 4.13 and Fig. 4.13 C).

4.4.2 Physical parameters and DO

Physical parameters of water temperature, hardness, total dissolved solid

and DO were correlated with each other (Table 4.13 and Fig. 4.14 A, B and C).

Water temperature and DO were positively correlated with the correlation

coefficient of R2 = 0.0295 and least squares regression of Y = 0.1308 X +

25.085 that indicates the two parameters were slightly correlated (Table 4.13

and Fig. 4.14 A).

Hardness and DO were negatively correlated with the correlation


159.24 that indicates high correlation (Table 4.13 and Fig. 4.14 B).

59

Table 4.13. Values of Coefficient of correlation and regression equation

Correlation between two parameters

R2 Y = ax + b

T°C and pH 0.0683 1.5872 x + 13.727

Hardness and pH 0.0407 -15.628 x + 260.6

TDS and pH 0.1043 -48.411 x + 459.56

T°C and DO 0.0295 0.1308 x + 25.083

Hardness and DO 0.1022 -3.1058 x + 159.24

TDS and DO 0.1529 -7.3437 x + 132.48

T°C and BOD 0.003 0.2596 x + 25.468

Hardness and BOD 0.001 1.8797 x + 138.69

TDS and BOD 0.08 33.158 x + 43.056

T°C and F 0.0001 0.0013 x + 25.782

Hardness and F 0.1981 -0.6647 x + 169.61

TDS and F 0.3541 -0.5844 x + 115.03

T°C and Cl 0.0019 0.0225 x + 25.96

Hardness and Cl 0.0202 0.1009 x + 136.28

TDS and Cl 0.012 -0.1503 x + 97.752

pH and EC 0.0488 -0.0009 x + 7.7696

DO and EC 0.138 0.0117 x + 7.6331

BOD and EC 0.1986 0.002 x + 1.0593

Cl and EC 0.0193 -0.0596 x + 59.899

NO3 and EC 0.007 -0.0002 x + 0.3043

F and EC 0.0065 0.0002 x + 0.4998

T°C and NO3 0.0249 2.0294 x + 25.27

TDS and NO3 0.0108 -32.961 x + 99.369

60

(A) Water temperature and pH

(B) Hardness and pH

(C) Total dissolved solid and pH

Fig. 4.13. Correlation between physical parameters and water pH

in Inle lake

y = -48.411x + 459.56

R2 = 0.1043

0

50

100

150

200

250

300

350

5 6 7 8 9 10pH value

TDS

(mg

L-1)

y = -15.628x + 260.6 R2= 0.0407

0

50

100

150

200

250

5 6 7 8 9 10pH value

Har

dnes

s (m

g L-1

)

y = 1.5872x + 13.727 R2 = 0.0683

15

20

25

30

5 6 7 8 9 10

pH value

Tem

pera

ture

(°C

)

61

(A) Water temperature and DO

(B) Hardness and DO

(C) Total dissolved solid and DO

Fig. 4.14. Correlation between physical parameters and dissolved oxygen (DO)

in Inle lake

y = -7.3437x + 132.48 R2= 0.1529

0

50

100

150

200

250

300

350

0 5 10 15 20 25

DO (mg L-1)

TDS

(mg

L-1)

1

y = -3.1058x + 159.24 R2 = 0.1022

0

50

100

150

200

250

0 5 10 15 20 25

DO (mg L-1)

Har

dnes

s (m

g L-1

)

y = 0.1308x + 25.083R2 = 0.0295

10

20

30

40

50

0 5 10 15 20 25

DO (mg L-1)

Tem

pera

ture

(°C

)

62

Total dissolved solids and DO were negatively correlated with the


7.3437 X + 132.48 that indicates the two parameters were significantly

correlated in each parameter (Table 4.13 and Fig. 4.14 C).

4.4.3 Physical parameters and BOD


and BOD were correlated with each other (Table 4.13 and Fig. 4.15 A, B, C).

Water temperature and BOD were positively correlated with the correlation

coefficient of R2 = 0.003 and least squares regression of Y = 0.2596 X + 25.468

that indicates slight correlation (Table 4.13 and Fig. 4.15 A). Hardness and

BOD were positively correlated with the correlation coefficient of R2 = 0.001

and least squares regression of Y = 1.8797 X + 138.69 that indicates they were

slightly correlated (Table 4.13 and Fig. 4.15 B). Total dissolved solids and

BOD were negatively correlated with the correlation coefficient of R2 = 0.08

and least squares regression of Y = 33.158 X + 43.056 that indicates the two

parameters were significantly correlated (Table 4.13 and Fig. 4.15 C).

4.4.4 Physical parameters and fluoride ion concentration


and BOD were correlated with each other (Fig. 4.16 A, B and C).

Water temperature and fluoride were positively correlated with the


0.0013 X + 25.782 that indicates slight correlation (Table 4.13 and Fig. 4.16

A).

Hardness and fluoride were negatively correlated with the correlation


169.61 that indicates the two parameters were slightly correlated in each

parameter (Table 4.13 and Fig. 4.16 B).

63

(A) Water temperature and BOD

(B) Hardness and BOD

(C) Total dissolved solid and BOD

Fig. 4.15. Correlation between physical parameters and biochemical oxygen

demand (BOD) in Inle lake

y = 33.158x + 43.056 R2 = 0.08

0

50

100

150

200

250

300

350

0 1 2 3 4 5

BOD (mg L-1)

TDS

(mg

L-1)

y = 1.8797x + 138.69 R2 = 0.001

0

50

100

150

200

250

0 1 2 3 4 5

BOD (mg L-1)

Har

dnes

s (m

g L-1

)

y = 0.2596x + 25.468R2 = 0.003

0

5

10

15

20

25

30

35

0 1 2 3 4 5

BOD (mg L-1)

Tem

pera

ture

(°C

)

64

(A) Water temperature and fluoride ion concentration

(B) Hardness and fluoride ion concentration

(C) Total dissolved solid and fluoride ion concentration

Fig. 4.16. Correlation between physical parameters and fluoride ion

concentration in Inle lake

y = -0.5844x + 115.03 R2 = 0.041

0

50

100

150

200

250

300

350

0 20 40 60 80 100

Fluoride (mg L-1)

TDS

(mg

L-1)

y = -0.6647x + 169.61R2 = 0.1981

0

50

100

150

200

250

0 20 40 60 80 100

Fluoride (mg L-1)

Har

dnes

s (m

g L-1

)

y = 0.0013x + 25.782R2 = 0.0001

15

17

19

21

23

25

27

29

31

0 20 40 60 80 100

F (mg L-1)

Tem

pera

ture

(°C

)

65

Total dissolved solids and fluoride were negatively correlated with the


0.5844 X + 115.03 that indicates significant correlation between the two

parameters (Table 4.13 and Fig. 4.16 C).

4.4.5 Physical parameters and chlorides

Physical parameters of water temperature, hardness, total dissolved

solids and chlorides were correlated with each other (Fig. 4.17 A, B and C).

Water temperature and chloride were positively correlated with the

correlation coefficient of R2 = 0.0019 and least squares regression of

Y = -0.0025 X + 25.96 that indicates slight correlation (Table 4.13 and Fig.

4.17 A).

Hardness and chlorides were negatively correlated with the correlation


136.28 that indicates the two parameters were slightly correlated (Table 4.13

and Fig. 4.17 B).

Total dissolved solid and chlorides were negatively correlated with the


0.1503 X + 97.752 that indicates the two parameters were significantly

correlated (Table 4.13 and Fig. 4.17 C).

4.4.6 Chemical parameters and electrical conductivity

Chemical parameters of pH, DO, BOD, chlorides, nitrates, fluoride were

correlated with EC (Fig. 4.18 A, B, C, D, E and F).

Water pH and EC were positively correlated with the correlation


7.7696 that indicates they were slightly correlated (Table 4.13 and Fig. 4.18 A).

66

(A) Water temperature and chloride ion concentration

(B) Hardness and chloride ion concentration

(C) Total dissolved solid and chloride ion concentration

Fig. 4.17. Correlation between physical parameters and chloride ion

concentration in Inle lake

y = -0.1503x + 97.752 R2 = 0.012

0

50

100 150 200 250 300 350

0 100 200 300

Chlorides (mg L-1)

TDS

(mg

L-1)

y = 0.1009x + 136.28R2 = 0.0202

0

50

100

150

200

250

0 50 100 150 200 250 300

Chlorides (mg L-1)

Har

dnes

s (m

g L-1

)

y = -0.0025x + 25.96R2 = 0.0019

0 5

10 15 20 25 30 35

0 50 100 150 200 250 300

Chlorides (mg L-1)

Tem

pera

ture

(°C

)

67

(A) pH and EC

(B) DO and EC

(C) BOD and EC

Fig. 4.18. Correlation between chemical parameters and electrical conductivity

in Inle lake

y = 0.002x + 1.0593 R2 = 0.1986

0

0.5

1

1.5

2

2.5

3

3.5

0 200 400 600

EC (μs cm-1)

BOD

(mg

L-1)

y = -0.0117x + 7.6331 R2 = 0.138

0

5

10

15

20

25

0 100 200 300 400 500 600

EC (μs cm-1)

DO

(mg

L-1)

y = -0.0009x + 7.7696R2 = 0.0488

5

6

7

8

9

10

0 100 200 300 400 500 600

EC (μs cm-1)

pH v

alue

68

(D) Chloride ion concentration and EC

(E) Nitrate compound and EC

(F) Fluoride ion concentration and EC

Fig. 4.18. Correlation between chemical parameters and electrical conductivity

(Contd.) in Inle lake

R2

0

0.5

1

1.5

0 100 200 300 400 500 600

EC (μs cm-1)

Fluo

rides

(mg

L-1)

y = -0.0002x + 0.3043R2 = 0.007

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 100 200 300 400 500 600

EC (μs cm-1)

Nitr

ates

(mg

L-1)

y = -0.0596x + 59.899 R2 = 0.0193

0

50

100

150

200

250

300

0 100 200 300 400 500 600

EC (μs cm-1)

Chl

orid

es (m

g L-1

)

y = 0.0002x + 0.4998R2 = 0.0065

69

DO and EC were negatively correlated with the correlation coefficient

of R2 = 0.138 and least squares regression of Y = -0.0117 X + 7.6331 that

indicates they were highly correlated (Table 4.13 and Fig. 4.18 B).

BOD and EC were negatively correlated with the correlation coefficient

of R2 = 0.1986 and least squares regression of Y = 0.002 X + 1.0593 that

indicates the two parameters were significantly correlated (Table 4.13 and Fig.

4.18 C).

Chlorides and EC were positively correlated with the correlation


59.899 that indicates they were slightly correlated (Table 4.13 and Fig. 4.18 D).

Nitrates and EC were negatively correlated with the correlation


0.3043 that indicates they were highly correlated (Table 4.13 and Fig. 4.18 E).

Fluoride and EC were negatively correlated with the correlation


0.4998 that indicates they were significantly correlated (Table 4.13 and Fig.

4.18 F).

4.4.7 Water temperature and nitrates

Water temperature and nitrates were positively correlated with the


2.0294 X + 25.27 that indicates they were slightly correlated (Table 4.13 and

Fig. 4.19 A).

4.4.8 Total dissolved solids and nitrates

Total dissolved solids and nitrates were positively correlated with the


70

32.961 X + 99.396 that indicates slightly correlated (Table 4.13 and

Fig. 4.19 B).

71

(A) Nitrate compound and water temperature

(B) Nitrate compound and total dissolved solid

Fig. 4.19. Correlation between nitrate compound and physical parameters

in Inle lake

y = -32.961x + 99.396R2 = 0.0108

0

50

100

150

200

250

300

350

0 0.2 0.4 0.6 0.8 1

Nitrates (mg L-1)

TDS

(mg

L-1)

y = 2.0294x + 25.27 R2 = 0.0249

0

5

10

15

20

25

30

35

0 0.2 0.4 0.6 0.8 1

Nitrates (mg L-1)

Tem

pera

ture

(°C

)

72

CHAPTER 5

DISCUSSION

The water depth of Inle Lake had seasonal fluctuation. In my study the

water level was deepest in October, November, December, and January.

February, March, April, May, June, July, August and September had normal

range. Fluctuation of water depth was found more in the centre of the lake than

at the lake margin. It may be due to deposition of sediments in the centre of the

lake.

According to Chapman (1992), conductivity or specific conductance is a

measure of the ability of water to conduct an electric current. It is sensitive to

variations in dissolved solids, mostly mineral salts. Conductivity is expressed

as microsiemens per centimeter (μs cm-1) and, for a given water body, is related

to the concentrations of total dissolved solids and major ions. The conductivity

of most freshwater ranges from 10 to 1000 μs cm-1 but may exceed 1000 μs

cm-1, especially in polluted waters, or those receiving large quantities of land

run-off (WHO). The electrical conductivity of Inle lake ranged from 42 μs cm-1

to 483 μs cm-1 which did not exceed WHO standard of 1000 μs cm-1.

The substances remaining after evaporation and drying of a water

sample are termed the "residues" (Bartram and Ballance, 1996). The residue is

approximately equivalent to the total content of the dissolved and suspended

matter in the water sample. Non-filterable residue corresponds to the total

suspended solids and the filterable residue is the total dissolved solids or waste

water. In Inle Lake the total dissolved solids (TDS) ranged from 25 mg L-1 to

289 mg L-1. The WHO standard guideline value is 1,000 mg L-1.

On the basis of EC and TDS values still under WHO standards, Inle

Lake water is good with solids, minerals and ions at acceptable levels.

Chapman (1992) is of the opinion that the type and concentration of

suspended matter control the turbidity and transparency of the water.

73

Suspended matter consists of silt, clay, fine particles of organic matter, soluble

organic compounds, plankton and other microscopic organisms. Turbidity

results from the scattering and absorption of incident light by the particles and

the transparency is the limit of visibility in the water. Both can vary seasonally

according to biological activity in the water column and surface run-off

carrying soil particles. Heavy rainfall can also result in hourly variations in

turbidity (Chapman, 1992).

Rain falling upon the land runs off into water courses, it mechanically

transports soil with it in the form of silt and clay particles. This form of

turbidity reduces light penetration and photosynthetic activity, smothers

bottom-dwelling animals and plants, reduces waste-assimilation capacities, and

may impair or curtail fish spawning. Although high turbidities from soil

particles may not be lethal to fishes, turbid waters may affect the productivity

of an aquatic environment and the growth of fishes (Barnnett, 1970).

In the present study the turbidity from six study sites did not exceed 5

NTU. The WHO standard guideline value is 5 NTU in fresh water lakes.

Hence, Inle Lake had normal turbidity of less than 5 NTU.

Insoluble particles of solids, organic substances, microorganisms and

other minerals impact the passage of the light through water. Turbidity in

excess of 5 units is noticeable to the average water consumer and accordingly

represents an unsatisfactory condition for drinking water when exceeding

100 units NTU (Environmental Engineering Laboratory, Department of Civil

Engineering, Yangon Institute of Technology).

The hardness of water varies considerably from place to place. In

general, surface waters are softer than ground waters and hard waters originate

in areas where the tropical is thick and limestone formations are present. Soft

waters originate in areas where limestone formations are sparse or absent.

Water is commonly classified into three categories in terms of the

degree of hardness as soft (0 - 75 mg L-1), moderately hard (75 - 150 mg L-1)

hard (150 - 300 mg L-1), and very hard (above 300 mg L-1) according to

74

Yangon Institute of Technology Department of Civil Engineering,

Environmental Engineering Laboratory.

The WHO standard guideline value of hardness is 500 mg L-1. In my

analysis the hardness value ranged from 44 mg L-1 to 210 mg L-1. hence, Inle

Lake is found to be a moderately hard water lake.

Water bodies undergo temperature variations along with normal climatic

fluctuations. These variations occur seasonally and, in some water bodies, over

periods of 24 hours. Lakes and reservoirs may also exhibit vertical stratification

of temperature within the water column. The temperature of surface waters is

influenced by latitude, altitude, season, time of day, air circulation, cloud cover

and the flow and depth of the water body. In turn, temperature affects physical,

chemical and biological processes in water bodies and, therefore, the

concentration of many variables. As water temperature increases, the rate of

chemical reactions generally increases together with the evaporation and

volatilization of substances from the water. Increased temperature also

decreases the solubility of gases in water, such as O2, CO2, N2, CH4 and others.

Surface waters are usually within the temperature range of 0°C to 30°C

although "hot spring" may reach 40°C or more (Chapman, 1992).

Svobodova et al. (1993) reported that water temperature influenced the

rate of metabolism and therefore the growth rate; it was often critical to

spawning and to the development of normal embryos. In present work the

water temperature ranged from 18.1°C to 28.6°C in the Inle Lake.

Senapti and Alam (2003) reported that arsenic was a naturally occurring

element in rocks, soils and the waters that contact them. Other major sources of

arsenic include agricultural run-off and industrial effluents from metallurgy,

glassware ceramics, dyes, herbicides, pesticides, petroleum refining, wood hide

preservatives, fertilizers and phosphate detergents. Recognized as a toxic

element for centuries, arsenic today is a recognized major human health

concern because it can contribute to long term morbidity and mortality.

75

The WHO standard guideline value of arsenic is 0.05 mg L-1. Arsenic

was not detected in all study sites in the Inle Lake.

Bartram and Ballance (1996) reported that chloride anions were usually

present in natural waters. A high concentration occurs in waters that have been

in contact with chloride containing geological formations. Otherwise, a high

chloride content may indicate pollution by sewage or industrial waste or by the

intrusion of seawater or saline water into a freshwater body or aquifer.

Chapman (1992) also reported that high concentration of chlorides can

make waters unpalatable and, therefore, unfit for drinking or livestock

watering.

In pristine freshwaters, chloride concentrations are usually lower than 10

mg L-1 and sometimes less than 2 mg L-1. Higher concentration can occur near

sewage and other waste outlets, irrigation drains, salt water intrusions, in arid

areas and in wet coastal areas. As chloride is frequently associated with

sewage, it is often incorporated into assessments as an indication of possible

faecal contamination or as a measure of the extent of the dispersion of sewage

discharges in water bodies (Chapman, 1992).

Eastin (1977) reported that the use of chlorine in destroying disease-

causing bacteria in drinking water had probably saved the lives of millions of

people. But in recent years there has been considerable concern that it might

actually be the cause of serious human illness and even death. In 1972 the EPA

published its findings the chlorine was combining with organic compounds in

the water to form chlororganic compounds. Among those identified were

chloroform and carbon tetrachloride. In laboratory tests both of these chemicals

have caused cancer in rats and mice.

In my research work the chloride values ranged from 0 mg L-1 to

260 mg L-1 in the Inle Lake. The WHO standard for chlorides is 200 mg L-1 to

600 mg L-1. For this reason the content of chlorides in Inle Lake did not exceed

600 mg L-1 but in some places was more than 200 mg L-1. This could be due to

disposal of domestic sewage including feces into the lake by inhabitants.

76

Chapman (1992) reported that fluoride originates from the weathering of

fluoride-containing minerals and enters surface waters through run-off and

ground waters through direct contact. Liquid and gas emissions from certain

industrial processes (e.g. metal and chemical based manufacturing) can also

contribute fluoride ions (F-1) to water bodies. Measurement of fluoride content

is especially important when a water body is used for drinking water supply. At

high concentrations, fluoride is toxic to humans and animals and cause bone

disease. However, a slight increase in natural levels can help prevent dental

caries although, at higher concentrations (above 1.5 to 2.0 mg L-1), mottling of

teeth can occur (WHO, 1984).

Bartram and Ballance (1996) published dental require close control of

fluoride concentrations to roughly 1.0 mg L-1. The guideline value of

1.50 mg L-1 in drinking water has been proposed by WHO.

In my analysis the level of fluoride ranged from 0 mg L-1 to 1.15 mg L-1.

It is noted that Inle Lake fluoride concentration moderately fluctuated but was

under or equal to WHO standard value.

Chan, Benstead, Davies and Grubh (1999) defined that pH is a

measurement of hydrogen ions in water. It tells us whether the water is acidic,

neutral or alkaline. Usually aquatic organisms thrive in neutral pH (7) to

slightly alkaline pH (8) waters. Wetlands with shallow water and high

vegetation coverage tend to be slightly acidic because of the humus produced.

Svobodova et al. (1993) reported that the optimal pH range for fish is

from 6.5 to 8.5. Alkaline pH value above 9.2 and acidity below 4.8 can damage

and kill salmonids (e. g. brown and rainbow trout); and pH values above 10.8

and below 5.0 may be rapidly fatal to the cyprinids (especially carp and tench).

In my research the pH values ranged from 6.54 to 8.92. The WHO

standard guideline value is 6.5 to 8.5. So, among the six study sites most had

pH values slightly above 7 but the centre of lake had pH value similar to upper

limit of the standard of slightly over the standard. Therefore water of this lake

although alkaline, is still potable.

77

Svobodova et al. (1993) described that oxygen diffused into the water

from the air especially where the surface was turbulent and from the

photosynthesis of aquatic plants. On the other hand, oxygen is removed by the

aerobic degradation of organic substances by bacteria and by the respiration of

all the organisms present in the water. The concentration of oxygen dissolved

in water can be expressed as mg per litre (mg L-1) or as percentage of air

saturation value. Even in ponds where the oxygen levels have been satisfactory

during the summer, when plant growth was vigorous, severe oxygen

deficiencies can occur in the autumn when the plants begin to die and

decompose. This deficiency can be more pronounced if the sky is heavily

overcast during the day, so that the limited oxygen production by

photosynthesis is further reduced. In theses cases, the maximum oxygen

deficiency occurs just before daybreak.

Ballance (1996) reported that the dissolved oxygen concentration

depended on the physical, chemical and biochemical activities in the water

body, and its measurement provided a good indication of water quality.

Changes in dissolved oxygen concentrations can be an early indication of

changing conditions in the water body.

Chapman (1992) stated that in freshwaters dissolved oxygen (DO) at sea

level ranged from 15 mg L-1 at 0°C to 8 mg L-1 at 25°C. Concentrations in

unpolluted waters are usually close to, but less than, 10 mg L-1. Concentration

below 5 mg L-1 may adversely affect the functioning and survival of biological

communities and below 2 mg L-1 may lead to the death of most fish.

In Inle lake water, the concentration of DO levels ranged mostly from 2

mg L-1 to 19.5 mg L-1. According to the above interpretation, the DO levels of

Inle Lake are not very good for aquatic ecosystem. The WHO standard for DO

in fisheries and aquatic life is 5.0 to 9.0 and for drinking water is 4.0.

Chapman (1992) described that the biochemical oxygen demand (BOD)

is an approximate measure of the amount of biochemically degradable organic

matter present in a water sample. It is defined by the amount of oxygen

78

required for the aerobic micro-organisms present in the sample to oxidize the

organic matter to a stable inorganic form.

Biochemical oxygen demand (BOD) is the most commonly used

parameter to define the strength of a municipal wastewater or organic industrial

waste. It indicates the amount of decomposable organic matter in wastewater,

the larger the concentration, the greater the BOD and consequently more of the

nuisance potential. BOD therefore gives the amount of organic load.

The WHO standard guideline value of BOD in drinking water is

3 mg L-1 and for fisheries and aquatic life is 3.0 to 6.0 mg L-1. In my analysis

data the BOD value range from 0.25 mg L-1 to 3.00 mg L-1. Hence, in Inle Lake

organic pollution is still at the permissible low BOD level for aquatic life.

The main sources of nitrate pollution of surface water is the use of

nitrogenous fertilizers and manure on arable land leading to diffuse inputs, and

the discharge of sewage effluents from human settlement in lake.

Bayly and Williams (1973) stated that nitrates nitrogen may be present

in small amounts in fresh water. Nitrates represent the final product of the

biochemical oxidation of ammonia. Nitrate is the most oxidized form of

nitrogen and is an important plant nutrient.

High levels of nitrates or nitrites in plants and plant products may be

harmful to humans and to livestock. A major problem relates to the formation

of nitrosamines.

High rates of N fertilization of crops may lead to pollution of surface

and ground waters. Nitrate pollution of these surface and ground waters leads

to problems of eutrophication in lake.

Bartram and Ballance (1996) stated that in surface water, nitrate is a

nutrient taken up by plants and assimilated into cell proteins. Stimulation of

plant growth, especially of algae, may cause water quality problems associated

with eutrophication. The subsequent death and decay of algae produces

secondary effects on water quality, which may also be undesirable. High

79

concentrations of nitrates in drinking water may present a risk to bottle-fed

babies under three months of age because the low activity of their stomachs

favours the reduction of nitrates to nitrites by microbial action. Nitrite is readily

absorbed into the blood where it combines irreversibly with haemoglobin to

form methaemoglobin, which is ineffective as an oxygen carrier in the blood.

In sever cases a condition known as infantile methaemoglobinaemia may occur

which can be fatal for young babies.

Chapman (1992) stated that as the World Health Organization (WHO)

recommended maximum limit for drinking water is 10 mg L-1 NO3-N, waters

with higher concentrations represent a significant health risk. In lakes, levels of

nitrates in excess of 0.2 mg L-1 NO3-N tend to stimulate algal and microbial

growth and indicate possible eutrophic conditions.

In my study the concentrations of nitrate in Inle Lake ranged 0.01

mg L-1. Hence, the nitrates exceeded the standard level of 0.2 mg L-1 in many

places in Inle Lake. For this reason, the Inle Lake was found to be abundant in

aquatic plants, floating plants, water hyacinths, water lilies, submerged plants

and algal blooms in and around the lake. This condition in the Inle Lake leads

to eutrophic conditions.

The nitrate levels at the six sampling sites were all above 0.20 mg L-1

which was conductive to algal growth. Those high nitrate levels could be due to

disposal of human and domestic sewage and wastes especially in Kyezagone

village. Also samples collected in Lethit village were from floating plantations

using fertilizers and pesticides leading to high nitrate pollution in that site. The

water samples collected at the entrance to Mwepwe village were also high in

nitrates which could be due to churning of water by motor boat traffic leading

to upwelling of sediments. Water samples from Kela village, surrounded by

floating plantation, was similarly also high in nitrates. Interestingly, central Inle

site was highest in nitrates as pollutants from all other areas came to

accumulate in the central part. Another fact noted is that the Namlit chaung,

80

flowing into the Inle Lake, carried much sediments, had also nitrates above

0.20 mg L-1 level enhancing algal growth.

Based on Moss et al. (1993) who reported trophic level categories

according to nitrate levels (0.3 mg L-1 to > 1.5 mg L-1) in lakes, all the six

sampling sites, of the Inle Lake in my study were found to be undergoing

eutrophication (0.5 to > 1.5 mg L-1). However, more comprehensive sampling

is necessary to be conclusive regarding the exact eutrophic condition of the Inle

Lake.

Ballance (1996) described that phosphorous compounds are present in

fertilizers and in many detergents. Consequently, they are carried into both

ground and surface waters with sewage,industrial wastes and storm run-off.

High concentrations of phosphorus compounds may produce a secondary

problem in water bodies where algal growth is normally limited by

phosphorous. In such situations the presence of additional phosphorous

compounds can stimulate algal productivity and enhance eutrophication

processes.

Chapman (1992) reported that phosphorous is an essential nutrient for

living organisms and exists in water bodies as both dissolved and particulate

species. It is generally the limiting nutrient for algal growth and, therefore,

controls the primary productivity of a water body. Artificial increases in

concentrations due to man's activities are the principal cause of eutrophication.

It is recommended that phosphate concentrations are expressed as phosphorous,

i.e., mg L-1 PO4-P.

In most natural surface waters, phosphorous ranges from 0.005 to 0.020

mg L-1 PO4-P. High concentrations of phosphates can indicate the presence of

pollution and are largely responsible for eutrophication conditions.

In Inle lake the concentration of PO4-P was 0 mg L-1 to 1 mg L-1. The

WHO standard guideline value is 0.005 mg L-1 to 0.020 mg L-1. Hence, the

present study sites were found to have more than 0.020 mg L-1 PO4-P in many

81

samples. Therefore, these concentrations of PO4-P could stimulate the algal

growth and algal blooming observed in and around the Inle Lake.

Regarding phosphates, the PO4-P levels at all my six sampling sites

were above the WHO standard of 0.005 mg L-1 to 0.020 mg L-1. PO4-P was

especially high in the months of March, April, May and also in August,

September, October and November. The reason for this could be reduction of

water level in the dry hot and dry cold periods leading to more concentration of

phosphates enhancing algal growth in Inle Lake. This is in agreement with

Correll (1998) who stated phosphorous entering lakes could stimulate algal

growth. One obvious input of phosphates in Inle Lake occurred through

application of phosphate fertilizers to the plantations over long periods, and

another pathway could be through excessive use of detergents by humans

residing in and around the lake.

The highest level (1.0 mg L-1) of PO4-P found in Inle Lake indicated that

the lake was undergoing eutrophication. Chapman and Kimstach (1992) also

reported that high phosphate concentrations were responsible for eutrophic

conditions.

The low levels of phosphates in Inle Lake in some months could be due

to lack of fertilizer application when farmers ceased agricultural activities and

were doing other pursuits such as fishing. Another reason could be uptake of

the residuals phosphates by plants and algae during these months. This is also

in agreement with the statement that in freshwaters high phosphate

concentrations are rare as they are actively taken up by plants (Chapman,

1992).

Correll (1998) reported that in lakes, if primary production was low, DO

was still sufficient at the bottom where P was stored in sediments, and when

primary production was high, DO was low and P was released from sediment

into water leading to eutrophication.

83

SUMMARY

1. Fourteen water parameters were monthly detected in six study site in Inle

Lake from March 2006 to February 2007.

2. The highest water depth was recorded in the centre of the lake in October.

The water level was higher in wet season than in dry season in all study

sites. Water depth was more fluctuated in the margin of the lake than in

the centre.

3. Electrical conductivity and total dissolved solid were highest in human

sediment area (Namlit-chaung) than other study sites. The parameter was

higher in dry season than the raining season. The pH level was found to

vary in different study sites. The water temperature was relatively

constant with seasons compared with air temperature.

4. Observed some native water gardens, whose used in agricultural

fertilizers, pesticides, herbicides, fungicides that are influence in lake

water.

5. Correlation between water quality of physical, chemical and nutrients

were recorded.

6. The nitrate and phosphate indicated that Inle lake water quality is in the

condition of initial state of eutrophication.

84

SUGGESTIONS FOR FUTURE WORK

1. The sedimentation rate of Inle lake should be investigated to establish the

potential internal nutrient loading.

2. A full ecological survey should be carried out to establish the richness of

flora and fauna in the lake.

3. The detail analysis of the causes of eutrophication in Inle lake should be

sought and assessment of the eutrophication status should be done.

4. Monitoring of water quality should be done after management programme

has been implemented.

85

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