UNCE, Reno, NV

Nutrients Phosphorus

Nitrogen

The biggest concern with excess nutrients The biggest concern with excess nutrients is eutrophicationis eutrophication

Results in:

• impacts on lake/stream ecology webs;

• toxins;

• drinking water treatment problems;

• other changes in lake chemistry

Dead plants decay Dead plants decay

Excess nutrients Excess nutrients

Excess aquatic plants Excess aquatic plants

Fish killsFish kills

Low dissolved Low dissolved oxygen oxygen

Freshwater Life Image Archive

Plants require Oxygen, Carbon, Nitrogen and Phosphorus in a fixed ratio

212 : 106 : 16 : 1 (by molarity –eg moles/liter)

109 : 41 : 7.2 : 1 (by weight- eg mg / liter)

Redfield Ratio

Nutrient Limitation

Typically N or P is “limiting” to aquatic plant production (not present at Redfield ratio)

Adding more of the limiting nutrient increased biological production until another nutrient or other factor limits growth

212 : 106 : 16 : 1 (by atoms)

109 : 41 : 7.2 : 1 (by weight)

To determine limiting nutrient

measure the ratio of N:P in a water body and compare to Redfield ratio

16 : 1 (by atoms) = molar ratio

7.2 : 1 (by weight)

Ratios of Total N to Total P < 10 (by weight)

=> N limits algal growth Ratios > 20 (by weight)

=> P limits algal growth

Ratios in between – “co-limitation” – response hard to predict

Why focus on phosphorus?

“Traditional” view (which many question):Phosphorus assumed to be limiting in many pristine waters in mid-latitudes

Many studies have demonstrated relationship between phosphorus loading to lakes and increased algae

Practical view (which fewer question):

In many cases, reducing phosphorus reduces algae

Phosphorus removal much more feasible and less expensive

Phosphorus Cycle

Natural phosphorus sources:

Terrestrial rocks

Marine sediments

Sediment

Guano

Organic material

Atmospheric deposition

Human phosphorus sources

(often more biologically available)

Sediment

(agriculture, logging, construction)

Fertilizers

Animal waste

Septic tanks

Wastewater treatment

Aquatic phosphorus cycle:

Animal tissue

Plant tissue

Water:Dissolved inorganic P

(DIP)

Dissolved /ParticulateOrganic P

(POP, DOP)

Bacterial tissue

Lake Sediment

Phosphate-bearing rock

Phosphorus in water occurs in many mineral forms and in biological material

Dissolved total phosphorus • inorganic + organic

Orthophosphate (orthophosphate = PO4)• inorganic

Total phosphorus = all phosphorus in water• dissolved and particulate, inorganic and organic

Dissolved Total Phosphorus

Filter the sample in the field, test for total P in filtered sample

Total Particulate Phosphorus

Subtract that amountfrom total P

Dissolved (< .45 um):• Phosphate ions (PO4)• Organic molecules• Other?

Particulate (> .45 um):• Mineral• Organic

Total Phosphorus (TP) = all phosphorus in the field sample

(“digest” entire sample)

Inorganic P:digest awayorganic phosphorus, test the remaining sample

Organic P:subtract Inorganic Pfrom total

Organic:• phosphorus incorporated into plant or animal materials• phosphorus in organic molecules

Inorganic:• mineral forms• phosphate ions (PO4)• poly-phosphates

Phosphorus can also be divided into organic and inorganic fractions

Phosphorus forms source, transport and fate

Particulate forms

May be very abundant in sediments.

Impact on water quality depends on local conditions.

Dissolved forms are more biologically “available”.

Phosphorus may be extremely soluble under certain chemical conditions (high pH, low oxygen) but comes out of solution in presence of iron, aluminum, magnesium, calcium in soil

Phosphate ion (PO43-) is the form utilized by plants

(AKA: Orthophosphate, Soluble Reactive Phosphorus)

Highly reactive, usually very low free concentrations

Reacts with iron oxides, calcium, mg, aluminum

Vertical distribution of oxidized and reduced conditions in lake sediments

(Mortimer, 1942)

Dep

th (

cm)

“Old” paradigm: (Mortimer 1942)Redox condition of sediments controls P release

pH affects phosphate adsorption with Fe(OH)3

We now understand that soluble versus particulate phosphorus may be controlled be chemical make-up of sediments and inflow water. Dominance of one form over another depends on rates, mixing, residence times.

Oxygen concentration of sediments and overlying water–

• Controlled by iron, aluminum compounds Microbial decomposition of organic bound P Dissolution of calcium-bound or manganese bound P pH of water Temperature

Epilimnetic phosphorus settles into hypolimnion where it is transformed further and may increase due to sediment release.

When lakes turn over, phosphorus is mixed back into entire water column

Variability in phosphorus in natural waters:

Higher concentrations of TP during high flows (associated with high sediment)

Biologically available forms may be extremely lowduring growing season

Daily and seasonal fluctuations in DO, pH may result in fluctuations of some forms of phosphorus

Extent of internal loading in reservoirs and lakes.

Nitrogen Cycle

Natural nitrogen sources:

Fixed atmospheric nitrogen

lightning

biologically mediated

Decomposition of organic materials

Human nitrogen sources

Synthetic fertilizers

Nitric and nitrous oxides in atmosphere (from burning fossil fuels)

Animal waste

Septic tanks

Wastewater treatment

Nitrogen is found in different inorganic forms

Ammonia/ Nitrite Nitrate Nitrogen gas Nitrous oxide Ammonium

(NH3) (NO2-) (NO3

-) (N2) (N2O) (NH4

+)

Very soluble

Move rapidly through soils into groundwater

Nitrate / nitrite can be toxic at high concentrations

Ammonia toxicity depends on pH and temperature and how long fish are exposed.

Nitrogen cycle:

Animal (Proteins)

Plants (proteins)

Water:NO3 and NH3

Soils(clay surfaces)

Detritus and Manure:Organic N and NH3

Atmospheric N:N2 , NxO, and NH3

Nitrogen FixationN2 NH3

(aerobic bacteria)

Nitrification NH3 NO2 NO2- NO3

(aerobic bacteria)

Denitrification NO3 N2O or N2

(anaerobic bacteria)

Nitrogen often described according to common chemical tests:

Nitrate + nitrite (NO3 + NO2)

Ammonia (NH3)

Total Kjeldahl Nitrogen (TKN) = organic N + ammonia nitrogen

Total Nitrogen = TKN + Nitrate + Nitrite

Other common “fractions” of nitrogen

Oxidized nitrogen = nitrate + nitrite

Inorganic nitrogen = oxidized nitrogen + ammonia

Organic nitrogen = TKN – ammonia

Total nitrogen = TKN + oxidized nitrogen

Variability in nitrogen concentrations in natural waters

May have higher concentrations of TN during high flows (associated with runoff)

Generally ammonia and nitrite very low in unpolluted waters

Nitrate may decline during growing season

BUT DIN may increase in concentration during base flow

Toxic forms of ammonia (NH3+) may vary due to daily and seasonal fluctuations in pH and temperature

PhosphorusPhosphorus NitrogenNitrogenGeochemical Cycling Slow Fast

Human-caused sources Human /animal waste, fertilizer, sediment

Human/animal waste, fertilizer, burning fossil fuels

Gaseous form? No Yes

Soluble forms OrthophosphateDissolved organic

Nitrate / nitrite / ammonia

Movement through soil / groundwater?

Often no Yes

Atmospheric deposition? Dust NOx, Ammonia

Toxic? NO Some forms

Causes eutrophication? Yes Yes

Limiting nutrient? Sometimes Sometimes

Impacts of Excess Nutrients

Problems caused by oxygen depletionProblems caused by oxygen depletion

Loss of fish and other aquatic lifeLoss of fish and other aquatic life

Enhanced phosphorus release from Enhanced phosphorus release from

sedimentssediments

Problems caused by excess plantsProblems caused by excess plants

Loss of aesthetic valueLoss of aesthetic value

Loss of recreational valueLoss of recreational value

Loss of fish habitatLoss of fish habitat

University of Michigan photo

Harmful algal bloomsHarmful algal blooms

Toxicity Toxicity

Liver toxins Liver toxins

NeurotoxinsNeurotoxins

RashesRashes

Drinking water impacts Drinking water impacts

– – surface water sourcessurface water sources

(1986,1987 average water use, figure from UDNR)

Bob Clement, EPA Region 8

Drinking water treatment issuesDrinking water treatment issues

Nitrates in groundwaterNitrates in groundwater

(1986,1987 average water use, figure from UDNR)

Blue baby syndromeBlue baby syndrome

At concentrations above above 10 ppmAt concentrations above above 10 ppm

Young ruminants and other livestock also susceptibleYoung ruminants and other livestock also susceptible

Ammonia toxicity Ammonia toxicity

Ammonium (ionized) form is not toxic fishAmmonium (ionized) form is not toxic fish

Unionized form is very toxicUnionized form is very toxic

Ratio of the two depends on pH and temperatureRatio of the two depends on pH and temperature

Reef Central http://www.reefcentral.com/forums/index.php?s=

Eutrophication –ecosystem effectsEutrophication –ecosystem effects

Zooplankton may be selective grazers

diatoms, green algaemore edible algae

Cyanobacteria (blue green algae) – less edible – may be in large colonies, gelatinous, toxic

Phosphorus impacts –

Nutrient concentrations, algal abundance (Chl a) and water transparency

Sewage diverted

Limnology and Oceanography, 1981

The Lake Washington Story

http://www.kingcounty.gov/environment/waterandland/lakes/lakes-of-king-county/lake-washington/lake-washington-story.aspx

Industrial scale fixation of atmospheric N to ammonia

Today, this process responsible for deeding ~ 1/3 of earth’s population.

Process consumes ~ 1% of world’s energy use

On average 50% of nitrogen in human body is synthetic

Haber-Bosch process

1 kg N /ha = 100 mg/m2

Estimated total reactive nitrogen deposition from the atmosphere (wet and dry) – early 1990s. Biggest increases in industrialized nations – automobile exhaust, agricultural fertilization, other sources www.cbd.int/doc/gbo2/cbd-gbo2.pdf

Nitrogen impacts -

Drainage from Mississippi River Basin Hypoxia Zone in Gulf of Mexico

Areal extent of Gulf of Mexico bottom water

hypoxia

Mississippi River nitrates at St. Francisvile

... Nitrate-N (mg/liter)

__ Nitrate_N flux (million MT/yr)

Estimated nitrogen fertilizer use in the Mississippi River Basin

Estimated land drainage in Mississippi River Basin

1900 1920 1940 1960 1980 2000

From USDA 1987, Goolsby et al 1999, Rabalais et al 1999

• Humans are adding 125 MT/Year to N Cycle• Total addition to terrestrial regions is 390 MT/Year• Total denitrification is 317 MT /Year

By one estimate, balance could be reached by reducing human additions to 52 MT/Year

Controlling nutrients – Controlling nutrients – Which nutrient?Which nutrient?What sources?What sources?

Directly Measuring Nutrient LimitationDirectly Measuring Nutrient Limitation Whole-lake bioassay: Whole-lake bioassay: Lake 226Lake 226in Canadian Experimental Lakes Areain Canadian Experimental Lakes Area

http://www.umanitoba.ca/institutes/fisheries/226curt.jpg

AddedN + C

N + P + C

Schindler concluded thatP limited algal growth in Lake 226

Lake 226 North

Lake 226 South

P-limitation and N-FixationP-limitation and N-FixationSchindler’s argumentSchindler’s argument

David Schindler argued that N should never be limiting, David Schindler argued that N should never be limiting, because if it were, then N-fixing cyanobacteria would because if it were, then N-fixing cyanobacteria would invade and fix readily available nitrogen gas (Ninvade and fix readily available nitrogen gas (N22) into ) into

ammonia:ammonia:

NN22 + energy (photosynthesis) + energy (photosynthesis) NH NH33

Bottle/or Microcosm Nutrient addition bioassays

for assessing nutrient limitation

Elser, J.J. et al. 2007. Nitrogen and phosphorus limitation of primary producers in freshwater, marine and terrestrial ecosystems. Ecol. Letters 10:1-8.

Re

sp

on

se

Ra

tio

Meta-analysis of Meta-analysis of hundreds of hundreds of

bioassaysbioassays

Regional Differences in N vs P limitationRegional Differences in N vs P limitation

3 general approaches for managing nutrient 3 general approaches for managing nutrient loadingloading

Reduction in nutrient inflowReduction in nutrient inflow

Approaches for Managing Nutrient Loading Approaches for Managing Nutrient Loading

Disruption of internal nutrient cyclesDisruption of internal nutrient cycles

Approaches for Managing Nutrient Loading in Approaches for Managing Nutrient Loading in aquatic systemsaquatic systems

Acceleration of nutrient outflowAcceleration of nutrient outflow

Vollenweider loading model

Sedimentation rate, rs ≈ rf 0.5 (unitless)

Hydraulic flushing rf ≈ outflow volume / Lake volume (unitless)

But see:Brett, MT & MM Benjamin. 2008. A review and reassessment of lake phosphorus retention

and the nutrient loading concept. Freshwat. Biol. 53: 194-211

Tropic State Index (TSI)

Carlson (dipin.kent.edu/tsi.htm)

Continuous index from 0-100 based on either:

Chlorophyll Secchi depth

TP

Defining EutrophicationDefining Eutrophication Arbitrary scalesArbitrary scales

Run thru an example of loading Run thru an example of loading model / vollenweider…model / vollenweider…

In class.In class.

Phosphorus criteria in Utah :

Although TMDLs are site specific, often….

0 .05 mg/liter probably will be stream concentration end point 0.025 mg/liter probably will be lake concentration end point

With no TMDL, these concentrations are “indicators”

Relationship between TP and algae holds in many regions

In Utah, probably over-estimates “bioavailable” phosphorus

Nitrogen criteria in Utah :

Ammonia Criteria established for specific pH

and temperature conditions

NitrateNo criteria set for most uses

Indicator concentration of 4 mg/liter

Nitrate drinking water source criteria = 10 mg/liter

Nitrogen cycle:

Animal (Proteins)

Plants (proteins)

Water:NO3 and NH3

Soils(clay surfaces)

Detritus and Manure:Organic N and NH3

Atmospheric N:N2 , NxO, and NH3

Nitrogen FixationN2 NH3

(bacteria)

Nitrification NH3 NO2 NO2- NO3

(aerobic bacteria)

Denitrification NO3 N2O or N2

(anaerobic bacteria)

Transformations:

Physical processes:

sorption of ammonia to organiz and inorganic forms Volatilization

Microbial processes: Ammonification: transofrmation of organic nitrogen

to ammonia (2st step of mineralization)Can occur both aerobically and anaerobically.

Nitrification of ammonia: principle transformation mechanism – reduces 2 step process: Ammonium + Oxygen and Nitrosomonas (hetertrophic bacteria) NitriteNitrite + oxygen and Nitrobacter nitrate.

$$$ Costs?? $$$$$$ Costs?? $$$

Prevention is always cheaper than Prevention is always cheaper than treatmenttreatment

Value of fisheries and recreationValue of fisheries and recreation

Drinking water treatmentDrinking water treatment

New wells, sources of groundwaterNew wells, sources of groundwater

Health impactsHealth impacts

Eutrophication Causes: Increased nutrient availability

Eutrophication Interactions

Increase P & N Loading

Algal Growth

Hyplimnetic Deoxygenating

Zooplankton Refuge

Loss of cold-water fish habitat–

–

Zooplankton Size

–

% Colonial Cyanobacteria(cyanotoxins)

+

Anoxic Nutrient Release

+

+

Fish

+

Zooplankton Grazing

–

+

–

+

Sedimentation Rate

+

Macrophytes&

Periphyton

–

Transparency

–+

Eutrophication issues in Farmington Bay and the Great Salt Lake

Beneficial Use Designation

Farmington Bay

Aquatic WildlifeBrine shrimpBrine fliesBirds

Contact RecreationSwimmingHunting

Public healthOdors

0

500

1000

1500

2000

2500

mg

P

m-2

yr

-1

Jordan River + Central Valley - wetland removal

South Davis WWTP

Central Davis WWTP

North Davis WWTP

Sewer CanalEutrophic

Hyper-Eutrophic

Nutrient loading of one million+ people from WWTP to the shallow bay is extremely high, with predictions of

hypereutrophic conditions

Map & bidirectional flow

x

x

x

Waste Water Treatment

X Sampling stations

Waste Water TreatmentWaste Water Treatment

X Sampling stations

Gunnison Bay

Gilbert Bay

FarmingtonBay

P L

oad

ing

( m

g P

m-2 y

r-1 )

0

100

200

300

400

500

600C

hlor

ophy

ll a

(u

g / L

) +- S

E

Farmington Bay

Gilbert Bay

A O D F A J A O D F A J A O D F A J A O D

2002 2003 2005

2005 Ave.270 ug/L

Hypereutrophic

Eutrophication

High nutrient loading produces excessive

algal growths

At salinities < 5%, a large portion of the algal

biomass is often composed of toxic

cyanobacteria (blue-green algae),

Nodularia spumigena

http://www.cdc.gov/hab/cyanobacteria/default.htm

0

10

20

30

40

50

60

70

80

90

100

UTAH'S 130 PRIORITY LAKES

TROP

HIC

STA

TE I

NDEX

Farmington Bay

Trophic State Index

0

10

20

30

40

50

60

70

80

90

100

UTAH'S 130 PRIORITY LAKES

TROP

HIC

STA

TE I

NDEX

Farmington Bay

Trophic State Index

0

10

20

30

40

50

60

70

80

90

100

UTAH'S 130 PRIORITY LAKES

TROP

HIC

STA

TE I

NDEX

Farmington Bay

Trophic State Index

Although it is not on the Utah’s 303d list of impaired waters, Farmington Bay is the most

eutrophic water body in the State of Utah.

http://

Phosphorus (mg / L)

Farmington Bay 2005

www.forester.net/sw_0201_evaluating.html#b

Algal densities in Farmington Bay are extreme.

The chlorophyll concentration in Farmington Bay in 2005 (270 μg/L; red star) was higher than 750 lakes studied world-wide to relate phosphorus levels to chlorophyll.

Farmington Bay IS “off-the-chart”

0

2

4

6

8

10

122003

DO

(m

g/L

)S

alin

ity

(%)

Salinity @ 0.2 m

O2 - 0.9 m

O2 - 0.2 m

25 K winds

Harsh chemical environment

• Anoxia (diel; several days)

• Toxic ammonia concentrations. >> EPA criteria by 50-400%.

Cyanotoxins from the abundant Nodularia in Farmington Bay are hepatotoxins and tumor promoters. Cyanotoxins accumulate in ducks and advisories for eating ducks have been

suggested for countries boarding the Baltic Sea (Sipia et al. 2006)

Farmington Bay is not safe for swimming!

0

20

40

60

80

100

120

2-May 1-Jun 1-Jul 1-Aug 31-Aug

No

du

lari

n (

ug

-Eq

uiv

LR

)

Farmington Bay

Bear River Bay

Gilbert Bay

Cyanotoxin Concentrations

(2006)

The Capital Times, Madison Sept. 6, 2003

World Health Organization

Moderate Health Effects (20 ug/L)

Mild Health Effects (2-4 ug/L)

Human Health

Harmful Algal Blooms (HABS)

Health effects of contact during recreation (no ingestion):

“Effects of skin irritation, skin rash, as well as vomiting, diarrhea, cold/flu symptoms, mouth ulcers and fever” at above 5,000

cyanobacterial cells per ml” (World Health Organization 2003). Cyanobacterial cells

in Farmington Bay have exceeded this level >100-fold.

Farmington Bay and the Bridger Bay Swimming Beaches Are Not Safe

Waters from Farmington Bay impact Bridger Bay swimming beach.

A rash (somewhat less intense than photo) was viewed on a child playing in water near Bridger Bay that had overflow waters from Farmington Bay (May 2005). These rashes, although severe, are not life-threatening and affect 10-20% of

population (Pilotto et al. 2004).

Farmington Bay Eutrophication Farmington Bay Eutrophication ‘Spilling” into Gilbert Bay‘Spilling” into Gilbert Bay

MODIS MODIS Satellite Satellite Image Image

(30 May 2006)(30 May 2006)FarmingtonFarmington

BayBay

SLCSLC

Causes: Causes: Increased nutrient availabilityIncreased nutrient availability Non-Point SourcesNon-Point Sources

Atmospheric deposition of nitrogenAtmospheric deposition of nitrogen

Atmospheric deposition has increased markedly in industrialized countries from automobiles exhaust, agricultural fertilization and other sources