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HALMSTAD UNIVERSITY
SCHOOL OF BUSINESS AND ENGINEERING
Applied Environmental Science
Ecological Risk Assessment of Salts in
Swedish Freshwater Ecosystem
----A preliminary assessment for invertebrates and vertebrates
JIANG Huan
Supervisor: Sylvia Waara
Master Thesis in Applied Environmental Science, 15 Credits
Halmstad University, 2011/6
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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Abstract
Increasing salinity in freshwater ecosystems is considered as a serious environmental
problem in all inhabited continents. In order to know whether Swedish freshwater is at
risk an ecological risk assessment for some organism groups has been conducted for
seven kinds of salt (NaCl, KCl, Na2SO4, K2SO4, MgCl2, CaCl2, MgSO4). The
exposure assessment data was obtained from a database containing data from a
Swedish Monitoring Program conducted in 2000. Short-term and long-term toxicity
data for vertebrates and invertebrates were obtained from the open scientific literature
and the ECOTOX database hosted by the U.S. Environmental Protection Agency.
Fixed assessment factors were used for derivation of PNEC values. For short-term
testes it was set to 1000 and for long-term testes it was set to 100 or 50. The exposure
assessment data showed that the concentration of many salts in Gotland is higher than
in other region. The effect assessment result showed that invertebrates are more
sensitive to salts than vertebrates. Most data sets were recovered for Daphnia magna
which was shown to be most sensitive to K2SO4 and KCl. Very high risk quotients
were obtained for many Swedish freshwater ecosystems even though many of them
have a high biodiversity. The reason for this is unclear but it could be due to the size
of the fixed assessment factors which in general are used for persistent pollutants but
might not be suitable for salts. Another plausible explanation is that the treatment of
the effect data to fit the exposure data is not adequate and other methods have to be
explored.
Keywords: Salinity, Salt, Sweden, Freshwater, Risk Assessment.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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Abbreviations
PNEC Predicted No Effect Concentration
PEC Predicted Environmental Concentration
RQ Risk Quotients
EC50 Effect concentration to 50% of test organisms
LC50 Lethal concentration to 50% of test organisms
NOEC No Observed Effect Concentration
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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Content
Abstract ................................................................................................................... 1
Abbreviations .......................................................................................................... 2
Content .................................................................................................................... 3
1. Introduction ...................................................................................................... 5
2. Background ....................................................................................................... 6
2.1. Description of Swedish ecological freshwater ecosystem ...................... 6
2.2. Source of high concentration of salt in freshwater ecosystem............... 6
2.2.1. Road salt ....................................................................................... 6
2.2.2. Landfill leachate ........................................................................... 7
2.3. Effect of salt on invertebrate and vertebrate ......................................... 7
2.4. Description of Ecological risk assessment.............................................. 7
2.4.1. Hazard Identification ................................................................... 8
2.4.2. Ecological Exposure Assessment .................................................. 8
2.4.3. Ecological Effect Assessment........................................................ 8
2.4.4. Risk Characterization .................................................................. 8
3. Material and Methods ...................................................................................... 9
3.1. Hazard Identification ............................................................................. 9
3.2. Environmental Exposure Assessment .................................................... 9
3.3. Environmental Effect Assessment .......................................................... 9
3.3.1. Data collection for Effect Assessment .......................................... 9
3.3.2. Calculation of PNEC .................................................................. 10
3.4. Risk Characterization .......................................................................... 10
4. Result and Discussion ..................................................................................... 13
4.1. Environmental Exposure Assessment .................................................. 13
4.2. Environmental Effect Assessment ........................................................ 16
4.2.1. The biology of organisms used for studying the effect of salts .. 16
4.2.2. KCl .............................................................................................. 16
4.2.3. NaCl ............................................................................................ 16
4.2.4. MgCl2 .......................................................................................... 17
4.2.5. CaCl2 ........................................................................................... 28
4.2.6. K2SO4 .......................................................................................... 28
4.2.7. Na2SO4 ........................................................................................ 28
4.2.8. MgSO4 ......................................................................................... 29
4.2.9. PNEC values ............................................................................... 29
4.2.10. Sensitivity of Daphnia magna to different salts ........................ 30
4.2.11. General overview of PNEC values ............................................. 30
4.3. Risk Characterization .......................................................................... 31
4.3.1. RQ result for Chloride ............................................................... 31
4.3.2. RQ results for Sulfate ................................................................. 31
4.3.3. RQ results for Sodium ................................................................ 31
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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4.3.4. RQ results for Potassium............................................................ 31
4.3.5. RQ results for Magnesium ......................................................... 32
4.3.6. RQ results for Calcium............................................................... 32
4.3.7. General overview of RQ values .................................................. 32
5. Conclusion....................................................................................................... 41
Acknowledgement ................................................................................................. 42
References .............................................................................................................. 43
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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1. Introduction
Salinization is a serious environmental issue. Although salts are natural components
of the freshwater ecosystem, increasing concentrations of salts in water have a great
effect on freshwater aquatic ecosystems (Dunlop et al., 2008). With the increasing of
salinity levels, the species richness and growth of freshwater biota is decreasing (Hart
et al., 1991). In recent years the frequent use of road salt in Sweden may cause high
salt concentrations in the Swedish freshwater ecosystem. Many constructed wetlands
were applied in many fields to solve the problem of eutrophication. If the wetlands
were not treated well this may increase the salt level in wetland (Nielsen et al., 2003).
Some studies about salt toxicity have been done recent years, but few researches
about the salinity tolerance of plant, so this study is only focus on the salinity
tolerance of invertebrate and vertebrate. Sweden has 21 regions and it has many
freshwater resources it is therefore of importance to know whether the salt level in
Sweden pose a risk to the freshwater ecosystem.
According to the research work by (Tietge et al., 1997), the major toxic ions are Na+,
K+, Mg
2+, Ca
2+, Cl
-, SO4
2- and HCO-. While in another paper (Mount et al., 1997)
state that NaCl, Na2SO4, NaHCO3, KCl, K2SO4, KHCO3, CaCl2, CaSO4, MgCl2 and
MgSO4 are considered as major toxicants in freshwater test. So this study is mainly
focused on compounds NaCl, Na2SO4, NaHCO3, KCl, K2SO4, KHCO3, CaCl2, CaSO4,
MgCl2 and MgSO4. As only a very limited amount of data could be found about the
toxicities of CaSO4, NaHCO3, KHCO3 these salt were excluded from the study.
Therefore in this study only a risk assessment of NaCl, KCl, Na2SO4, K2SO4, MgCl2,
CaCl2, MgSO4 in Sweden freshwater ecosystems has been conducted.
The specific aims of this study were to:
- Conduct an ecological risk assessment of K+, Na
+, Mg
2+, Ca
2+, Cl
- and SO4
2-
in Swedish lakes and water courses.
- By comparing effect data from different species, identify which kind of
species that is the most sensitive one, and which compound that is the most
toxic to certain species.
- Quantify the potential threat of salts to freshwater ecosystem by conduct an
ecological risk assessments according to the European guidelines, and use the
predicted environmental concentrations from Sweden to predict the risk of
salinity in Sweden.
- Provide some data to support the decision making regarding the risk of
salinization in Swedish lakes and water courses.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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2. Background
2.1. Description of Swedish ecological freshwater ecosystem
Freshwater ecosystems are aquatic systems that contain drinkable water or water with
almost no salt content. Lakes and ponds, reservoirs, wetland, rivers and streams and
ground water are the major resources of freshwater. Freshwater is the main drinking
water resources for human and animals on the earth. Some major groups of organisms
known to inhabit freshwater ecosystems include vertebrates (e.g., fish, amphibians,
reptiles, birds, and mammals), invertebrates (e.g., protozoan, myxozoans, rotifers,
worms, and mollusks), plants, algae, fungi, and bacteria. Infectious agents such as
viruses may also be present. Periphyton, macrophytes (aquatic plants), insects, fish,
and amphibians are also found in freshwater environments (United State
Environmental Protection Agency, 2010).
Natural freshwater contain several ionic constituents at a higher level more than trace
level. Although ions as Na+, Ca
2+,Cl-, and some other ions are supporting aquatic life
many natural and anthropogenic sources can increase ion concentration to level toxic
o aquatic life (Mount et al., 1997). The major sources of salts like landfill leached
which bring lots of major ions and persistent pollutants into freshwater, deicing salt
bring lots of salts into streams from the roadscape or groundwater, using pesticide
also bring toxic compounds to the freshwater ecosystem. As a consequence, some
species are being threatened. Nowadays, people are much more concerned about the
safety of freshwater, because it is related to our drinking water and the conservation of
biodiversity. Study about the ecological risk assessment of salts became popular.
Sweden is the third largest country in West Europe with around 50% of land covered
by forests and about 10% of lands covered by lakes and rivers. Sweden have 21
regions, each region has different water condition. Some are in good condition, some
were polluted by people. In order to evaluate and monitor the water quality, some
sensitive species like Daphnia magna and Daphnia similis were used to test the water
quality. All test procedures assume that if the most sensitive species can stand the
certain concentration of toxicants, other species will not affected by the toxicants and
the water quality can be approved. This study used exposure data from a Nature
Survey conducted in 2000 (Swedish Environmental Protection Agencya, 2011) and
the previous toxicity test result to see each region’s water condition and see whether
the salt in Swedish freshwater have a risk to organisms.
2.2. Source of high concentration of salt in freshwater ecosystem
2.2.1. Road salt
The primary compound of road salt is sodium chloride. It is widely used worldwide to
aid in snow and ice removal. With the increasing of population pressures, the level of
migration from urban communities to suburbs, and the increasing commuting suggest
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
7
a need for higher usage of road salts in the future. From the roadscape, large amounts
of salts are delivered to rivers and streams by surface runoff. Although the application
of road salt has reduced the number of accidents caused by snow and ice, some
reports showed that NaCl has an effect on groundwater and surface water quality
(Blasius & Merritt, 2002). Road salt has also greatly contributed to the high
concentration of salt in the freshwater ecosystem.
2.2.2. Landfill leachate
Landfill leachate is liquid that percolates through a landfill. It converts the solids into
liquid form through a combination of physical, chemical and microbial processes (Xie
et al., 2010). The leachate has large amount of organic compounds, nutrients (nitrogen,
phosphorus), minerals and heavy metals, which will contribute to the increase of salt
concentration.
2.3. Effect of salt on invertebrate and vertebrate
- Invertebrates
Invertebrates are more sensitive to salt in freshwater compared to other species. From
research (Blasius & Merritt, 2002), the author demonstrated that high concentration of
NaCl may affect the movement of many kinds of invertebrate like Gammarus
(Amphipoda), and two species of limnephilid caddisflie. The survival of most
freshwater invertebrates dramatically decreased at water salinity between minimum
(0-20mg/L) and maximum values (>8g/L). (Berezina, 2003) When invertebrate
expose to high concentration of salt their heart rate will increase or decrease appetite.
With the increasing of salinity level, invertebrates become immobilized and
eventually die.
- Vertebrates
Fish are the most common vertebrates in freshwater. Fish are usually used as an
indicator for testing whether there is a risk for an ecological system. Several large
families of fishes are observably so strictly to freshwater, it’s hard to find them in
salinities approaching that of the sea(Myers, 1949). In most species egg fertilization
and incubation, yolk sac resorption, early embryogenesis, swim bladder inflation and
larval growth are dependent on salinity. For larger fish, the growth of fish is
controlled by salinity (Boeuf & Payan, 2001).
2.4. Description of Ecological risk assessment
An ecological risk assessment is the determination of a quantitative value of risk
about the specific situation and the assessment of the possible threat. The whole
ecological risk assessment consists of four parts. These are: hazard identification,
ecological exposure assessment, ecological effect assessment and risk
characterization.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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2.4.1. Hazard Identification
Hazard identification aims to determine the potential adverse effects of salt by
reviewing scientific articles.
2.4.2. Ecological Exposure Assessment
The ecological exposure assessment aims to determine the contaminant concentration
in the targeted ecosystem. It will also determine the predicted environmental
concentration by collecting data from authoritative organization.
2.4.3. Ecological Effect Assessment
Ecological effect assessment aims to find out the most sensitive species to each
contaminant and the highest concentration the species can tolerate over a long time.
The response of species to toxicants are showed in two ways, one is acute response
another is chronic response. Acute response like LC50 (lethal concentration to 50% of
test organisms) and EC50 (effect concentration to 50% of test organisms), they are all
test the short-term response of organisms to toxicants. Chronic responses like NOEC
(No Observed Effect Concentration) show the long-term response of organisms to
toxicants. The predicted no environmental concentration is calculated by using an
assessment factor. Assessment factors will consider the value of data and reduce the
uncertainty of the general factors that under certain circumstances may be changed.
2.4.4. Risk Characterization
Risk characterization aims to quantify the potential risk of contaminants to the
concrete situation.
This is usually presented for a selected chemical as a ratio between a measured or
predicted concentration in the environment as a PEC–value (Predicted Environmental
Concentration) and the result from an effect assessment as a PNEC-value (Predicted
No Effect Concentration).
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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3. Material and Methods
The whole study followed the European Chemicals Technical Guidance Document on
Risk Assessment Part 2 (European Commission, 2003) to evaluate the salt risk for
Swedish lakes and water courses. The general procedure is showed in Figure 1. The
risk assessment included four parts: the hazard identification, the environmental
exposure assessment, the environmental effect assessment and the risk
characterization. The procedures are shortly described below:
3.1. Hazard Identification
In the first instance, it is necessary to identify the major compound of salts in the
freshwater ecosystem. Several articles were read to find out which compounds are
more toxic to the ecosystem. According to the research work by (Tietge et al., 1996),
the major toxic ions are Na+, K
+, Mg
2+, Ca
2+, Cl
-, SO4
2- and HCO-. While in another
paper (Mount et al., 1997) NaCl, Na2SO4, NaHCO3, KCl, K2SO4, KHCO3, CaCl2,
CaSO4, MgCl2 and MgSO4 were considered as major toxicants in freshwater toxicity
test. Therefore, the intent of this study was to focus on the following compounds:
NaCl, Na2SO4, NaHCO3, KCl, K2SO4, KHCO3, CaCl2, CaSO4, MgCl2 and MgSO4.
As only a few data could be found about the toxicities of CaSO4, NaHCO3, KHCO3
only effect data for NaCl, KCl, Na2SO4, K2SO4, MgCl2, CaCl2, MgSO4 in Sweden
freshwater was used for derivation of RQs.
3.2. Environmental Exposure Assessment
Measured data was extracted from databases hosted by the Department of Aquatic
Sciences and Assessment, Swedish Agricultural University, Uppsala, Sweden for the
Swedish Natural Protection Agency. Data was obtained from a National Survey
Program in 2000 (Riksinventering), because the research in 2000 is more complete
than in other years. The data is only available in Swedish at the present time. This
study focus on the environmental concentration of the following ions: K+, Na
+, Mg
2+,
Ca2+
, Cl- and SO4
2-.
The measured data from each region in Sweden was compiled and a PECmax value and
a PECmin value for each region were calculated using the measured data.
3.3. Environmental Effect Assessment
3.3.1. Data collection for Effect Assessment
The U.S. Environmental Protection Agency ECOTOX database (United State
Environmental Protection Agencyb, 2011) was used to identify report and articles with
relevant toxicity data. The information was used to retrieve the original articles
through the library databases from Halmstad University.
Only a few articles provide the toxicity data in ionic forms, so this study only
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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collected the toxic data for salts.
The key words used in the search process were: salt, salinity, tolerance, NaCl, KCl,
Na2SO4, K2SO4, MgCl2, CaCl2, MgSO4, CaSO4, salt effect, EC50, LC50, NOEC,
freshwater, ecosystem.
3.3.2. Calculation of PNEC
Most data collected in this study were toxicity values for fish and water fleas. The
ecotoxicity data was evaluated for both the completeness and the adequacy. After the
evaluation of data, the PNEC was calculated by using fixed assessment factors. The
assessment factors are showed in Table 1.
Table 1. Fixed Assessment factors used to derive a PNECaquatic (European Commission,
2003)
Available data Assessment factor
At least one short-term L(E)C50 from
each of three trophic levels of the
baseset (fish, Daphnia and algae)
1000
One long-term NOEC (either fish or
Daphnia) 100
Two long-term NOECs from species
representing two trophic level (fish and
/or Daphnia and/or algae)
50
Long-term NOECs from at least three
species (normally fish, Daphnia and
algae) representing three trophic levels
10
Species sensitivity distribution (SSD)
method
5-1
(to be fully justified case by case)
Field data or model ecosystems Reviewed on a case by case basis
PNEC ensures an overall protection of the environment. It assumes the ecosystems
sensitivity depends on the most sensitive species in the ecosystem and protecting the
structure of ecosystem will protect the community function. By using these factors to
calculate PNEC it will reduce the difference between different tolerance values.
In the case of this study, assessment factor 1000, 100 and 50 were used to calculate
the PNEC depending upon the number and type of effect data obtained.
3.4. Risk Characterization
The quantitative risk characterizations were carried out by calculating PEC/PNEC
ratio (risk quotients) with the exposure assessment and the dose
concentration-response (effect) assessment.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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- In this study the unit of PEC values was converted from mekv into mmol/L to
make all data’s unit into mmol/L. 1 mekv= 1/∣x∣mmol/L, x refers to the
number of electron lost or got in one compound. For example, if the
concentration of SO42-
is 1 mekv, then it also can also be express as 0.5
mmol/L.
- In order to compare all the toxicity data easily, all units of toxicity data were
converted to mmol/L to make all units the same. Some data with unit mg/L, in
this study I used the data to divide the compound’s molecular weight, then I
got the data in unit mmol/L. For example, the concentration of NaCl is 1
mg/L, the concentration also can express like 0.001 g/L / 58.44 g/mol =
0.0171 mmol/L.
- The PNEC values for salts were used to calculate several ionic PNEC values
of each salt i.e. for NaCl an ionic PNEC values for Na and one for Cl was
derived.
- Predict the risk of each salt by using RQ.
RQ = PEC / PEC
If RQ > 1, there is a risk of the specific ion.
IF RQ < 1, there is no risk of the specific ion.
Since the RQ for each ion was made based upon PNEC values obtained from salts, the
combined ions have not been taken into account. The results derived by RQ may not
be quite accurate, but no other method is available at the present time unless all values
were converted to conductivity.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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Figure 1. General procedure for environmental risk assessment. Redrawn from
(European Commission, 2003)
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
13
4. Result and Discussion
The major salts considered in this study were NaCl, KCl, Na2SO4, K2SO4, MgCl2,
CaCl2, and MgSO4.
The major ions considered in this research were chloride (Cl-), sulfate (SO4
2-), sodium
(Na+), potassium (K
+), magnesium (Mg
2+) and calcium (Ca
2+).
4.1. Environmental Exposure Assessment
The exposure assessment data were obtained from Department of Aquatic Sciences
and Assessment, Swedish Agricultural University, Uppsala, Sweden. The data
presents the concentration of compounds in 2000. The data contain the highest
(PECmax) and lowest concentrations (PECmin) of chloride, fluoride, sulphate, sodium,
potassium, calcium and magnesium from different region. The data is shown in Table
2.
From Table 2, it is clear that the concentrations of major ions in freshwater ecosystem
in Gotland are quite high. This is probably due to the bedrock consisting of limestone
and the penetration of sea water from the Baltic Sea into the groundwater sources.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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Table 2. Measured concentrations of ions from different regions of a administration that were used as PEC values (Swedish Environmental
Protection Agency, 2000)
PEC
Administrative region Chloride(mmol/L) Sulfate (mmol/L) Sodium (mmol/L) Potassium (mmol/L) Magnesium (mmol/L) Calcium (mmol/L)
Max min max min max Min max min max min max min
Stockholms 10.63 0.054 1.3495 0.0305 7.861 0.068 0.249 0.006 1.0625 0.0225 2.691 0.052
Uppsala 0.954 0.05 2.074 0.01 1.239 0.097 0.151 0.01 0.5635 0.041 2.456 0.1255
Södermanlands 0.75 0.047 0.28 0.027 0.751 0.067 0.1 0.006 0.243 0.023 0.662 0.039
Östergötlands 0.787 0.055 1.2055 0.0165 0.799 0.076 0.135 0.009 0.271 0.02 2.6705 0.032
Jönköpings 0.58 0.068 0.481 0.0155 0.848 0.078 0.108 0.009 0.2315 0.0205 1.09 0.0345
Kronobergs 0.918 0.114 0.162 0.029 0.912 0.141 0.088 0.006 0.133 0.0295 0.3405 0.028
Kalmar 1.639 0.075 0.266 0.037 1.369 0.103 0.162 0.01 0.2485 0.036 0.4925 0.059
Gotlands 96.07 0.171 4.871 0.093 54.942 0.176 1.83 0.017 7.3075 0.091 2.9985 0.976
Blekinge 0.492 0.156 0.167 0.0255 0.615 0.198 0.061 0.012 0.1205 0.041 0.483 0.0635
Skåne 6.059 0.125 1.5275 0.025 4.282 0.174 0.172 0.013 1.157 0.028 3.2655 0.034
Hallands 0.47 0.115 0.187 0.0355 0.46 0.123 0.131 0.007 0.2425 0.0205 0.3425 0.012
Västra Götalands 65.838 0.067 3.295 0.012 41.71 0.075 1.312 0.005 5.2015 0.013 2.352 0.0065
Värmlands 0.947 0.017 0.0655 0.0055 0.9 0.025 0.052 0.002 0.093 0.0065 0.3705 0.015
Örebro 0.285 0.033 0.248 0.0135 0.24 0.039 0.08 0.004 0.1185 0.0135 1.284 0.019
Västmanlands 0.788 0.033 0.2445 0.012 0.725 0.047 0.11 0.004 0.2245 0.012 0.6685 0.0185
Dalarnas 0.24 0.003 2.846 0.0035 0.484 0.008 0.434 0 0.8295 0.002 2.401 0.002
Gävleborgs 0.559 0.008 0.3115 0.005 0.824 0.024 0.203 0.003 0.195 0.005 1.161 0.0155
Västernorrlands 0.544 0.011 0.1095 0.0085 0.556 0.029 0.092 0.002 0.139 0.009 0.324 0.018
Jämtlands 0.1 0.004 0.2885 0.004 0.12 0.009 0.039 0 0.281 0.002 1.78 0.003
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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Västerbottens 4.017 0.004 11.922 0.003 3.068 0.006 0.156 0 3.015 0.003 3.2085 0.003
Norrbottens 0.264 0.003 1.3365 0.0025 0.467 0.004 0.146 0 0.3515 0.0015 1.524 0.0015
max 96.07 0.171 11.922 0.0305 54.942 0.918 1.83 0.017 7.3075 0.091 3.2655 0.796
min 0.1 0.003 0.0655 0.0025 0.12 0.004 0.039 0 0.093 0.0015 0.324 0.0015
*Data with underline showed the highest PEC value in Sweden
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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4.2. Environmental Effect Assessment
4.2.1. The biology of organisms used for studying the effect of salts
In Table 3 and Table 4 biological information for the species included in the effect
assessment is presented.
4.2.2. KCl
- Data comparison
In Table 5, for the short-term data, 1.851 mmol/L is the lowest concentration;
Dreissena polymorpha is the most sensitive species to KCl.
For the long-term data, there are three toxicity data for fish; the most sensitive fish is
Pimephales promelas with a lowest value of 6.7 mmol/L. In the table 5, there are two
sets of data for Daphnia magna with the same exposure duration and age of organism,
but the values of them are different (9.926 mmol/L and 14.968-15.272 mmol/L
respectively), it may due to the different test parameters used in the experiment.
For the species group crustaceans, although the values are different, the difference are
not significant, they are all around 10 mmol/L, the most sensitive species to KCl is
Ceriodaphnia dubia.
For the fishes, the highest value comes from hepatocytes, the reason may due to the
short test duration and that cell lines was used. Among fish, the most sensitive species
to KCl is Pimephales promelas.
- Calculation of PNECKCl
In Table 5, three long-term NOECs from species representing one trophic level (fish)
is presented, fixed assessment factor 50 should be used. The lowest NOEC is higher
than the short term 24h-LC50 of Dreissena polymorpha, so according to the European
Commission Guideline the data of Dreissena polymorpha is used and a fixed factor of
100 to calculate PNECKCl.
PNECKCl = 1.851mmol/L / 100 = 0.01851 mmol/L
4.2.3. NaCl
- Data comparison
It can be seen in Table 6, for the short-term data that, there are five data sets for
Daphnia magna. The test parameters in the different experiments don’t seem to vary,
but there is still a difference in effect values as the data ranges from 28.421 mmol/L to
93.767mmol/L. Some differences can be explained by the use of different diets for
Daphnia magna or the use of different clones. The short-term data also included three
data for fish; the data for Carassius auratus are lower than that of Oncorhynchus
mykiss, this may due to the different exposure duration or sensitivity. For the
short-term data, the lowest value is 27.206 mmol/L.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
17
There are two long-term-data obtained in Table 6, one for fish and one for
Crustaceans. They were both tested for 7 days. The data for Ceriodaphnia dubia is
lower than the data for Pimephales promelas (25.666 mmol/L and 68.443 mmol/L
respectively).
For the Crustaceans group, there is one long-term data set and seven short-term data
sets, the data for Ceriodaphnia dubia is lower than the data for other species, this
indicated that Ceriodaphnia dubia is the most sensitive species to NaCl.
For the fish group, there is one long-term data set and three short-term data sets, the
lowest values come from the long-term value for Pimephales promelas
(68.443mmol/L). The differences between two data sets for Carassius auratus are
probably due to differences in the test solution range.
In all, 25.666 mmol/L is the lowest value; Ceriodaphnia dubia is the most sensitive to
NaCl.
- Calculation of PENCNaCl
In Table 6, two long-term NOECs from species representing two trophic levels (fish
and Crustaceans) are shown, so a fixed assessment factor of 50 can be used for
calculating PNECNaCl.
PNECNaCl = 25.666 mmol/L / 50 = 0.513 mmol/L
4.2.4. MgCl2
- Data comparison
All data in Table 7 are short-term data sets. Data sets are obtained from two species
(Daphnia magna and Pimephales promelas).
For the Crustaceans group, two day LC50 test for Daphnia magna has the lowest
value. Longer exposure duration shows lower toxicity values.
For the fish group, longer exposure duration shows lower toxicity data, the lowest
value is 22.266 mmol/L.
The lowest value in Table 7 is 13.969 mmol/L for Daphnia magna, accordingly,
Daphnia magna is more sensitive to MgCl2 than Pimephales promelas.
- Calculation of PENCMgCl2
The data presented in Table 7 are all short-term LE(C)50 values from two trophic
levels (fish and Daphnia). This study assumes that the two trophic levels can present
the toxicity of MgCl2. Therefore a fixed assessment factor 1000 was used to calculate
PNECMgCl2.
PNECMgCl2 = 13.969 mmol/L / 1000 = 0.014 mmol/L
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
18
Table 3. The biology of invertebrates used in the effect assessment
Species name Common
name Distribution
Life
span
Feeding
habits Size Productive habits Use
References
Ceriodaphnia dubia Water flea All over the world - - <1mm - live source food,
laboratory animal.
MBL Aquaculture,
2005
Daphnia magna Water flea Eurasia, Africa, North
America
< 2
month bacteria
5-6
mm
Sexual reproduction, sometimes it clones
itself, each produce 400 or more
generations.
fish food,
laboratory animal.
MBL Aquaculture,
2005; Koto et al.,2011
Dreissena
polymorpha
Zebra
mussel
German, America,
Poland 4-5years Particles 5.1cm
After 6-7 weeks it begins to reproduce,
may produce 30000-1000000 eggs per
year per female.
-
National Atlas of the
United States, 2005
Streptocephalus
rubicaudatus Shrimp
Africa, Australia,
Eurasia, North
America
- - - - -
Dumont & Adriaens,
2009
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
19
Table 4. The biology of vertebrates used in the effect assessment
Species name Common
name
Distribu
tion Life span Feeding habits Size Productive habits Use References
Carassius
auratus Goldfish East Asia
Maximum
41 years
Crustaceans, insects,
plant matter.
10cm,
0.91-2.3kg Egg hatch within 48-72h.
Game fish,
aquarium
fish.
Fishbase, 2010
Oncorhynchus
mykiss
Rainbow
trout
Asia, North
America 11 years
Insets, crustaceans, small
fish.
Maximum:
12m, 24kg
Sexually nature 2-3 years, egg
hatch in 50 days. Fishing food.
National Geographic,
2011
Pimephales
promelas
Fathead
minnow North America 3 years
A variety of aquatic
plants and animals. 66-70 mm
Sexual maturity during 1st
growing season, produce 10000
eggs in 3 month breeding season.
Baitfish, pets.
Paulson & Hatch,
2011; Montana Field
Guide, 2011
Salvelinus
fontinalis Brook trout North America 4-5 years
Crustaceans, frogs,
amphibians, insets,
molluscs, small fish.
25-65 cm,
0.3-3 kg -
Game fish
Trout Unlimited, 2011
Table 5. Short-term and long-term toxicity data for KCl Data in bold text represent the effect value used for derivation of the PNEC
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
20
Species Scientific
Name
Species
Common Name
Species
Group
Test
Type
Exposure
Duration
Age of
Species
Test
Temperature (℃)
weight
(g)
Length
(cm) Value (mmol/L) Reference
Ceriodaphnia
dubia Water flea Crustaceans LC50 1d <24h 20 - -
8.451
(7.914-8.451) Mount et al., 1997
Daphnia magna Water flea Crustaceans LC50 1d <24h 20 - - 9.926
(7.780-1.180) Mount et al., 1997
Daphnia magna Water flea Crustaceans EC50 1d <24h 21±1 - - 14.968-15.272 Lilius et al., 1994
Daphnia similis Water flea Crustaceans EC50 2d <16h 20 - - 9.255-15.962 Utz & Bohrer,
2001
Dreissena
polymorpha Zebra mussel Bivalve LC50 1d - - - 1.5-2.0 1.851 Fisher et al., 1991
Oncorhynchus
mykiss Rainbow trout Fish EC50 3h - 15 370 - 164.303-390.899 Lilius et al., 1994
Oncorhynchus
mykiss Rainbow trout Fish NOEC 7d 15-25d 15±1 - - 13.413-26.827
Lazorchak &
Smith, 2007
Pimephales
promelas Fathead minnow Fish NOEC 7d 4-16h 25±1 - - 6.707
Pickering et al.,
1996
Salvelinus
fontinalis Brook trout Fish NOEC 7d 30-45d 15±1 - - 26.827
Lazorchak &
Smith, 2007
Table 6. Short-term and long-term toxicity data for NaCl Data in bold text represent the effect value used for derivation of the PNEC
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
21
Species Scientific
Name
Species
Common
Name
Species
Group
Test
Type
Exposure
Duration
Age of
Species
Test
Temperature
(℃)
weight
(g)
Length
(cm) Value (mmol/L) Reference
Ceriodaphnia
dubia Water flea Crustaceans NOEC 7d <24h 20 - - 25.666 Degraeve et al., 1992
Ceriodaphnia
dubia Water flea Crustaceans LC50 2d <24h 25±2 - -
27.206
(26.008-28.574) Harmon et al., 2003
Carassius auratusc Goldfish Fish LC50 10d - 23.5 0.38-4.02 200
Threader & Houston,
1983
Carassius auratusd Goldfish Fish LC50 10d - 23.5 - 0.38-4.02 201.1
Threader & Houston,
1983
Daphnia ambigua Water flea Crustaceans LC50 2d <24h 21±2 - - 34.222
(30.970-37.644) Harmon et al., 2003
Daphnia magna Water flea Crustaceans LC50 2d <24h 21±1 - - 93.767
(86.752-103.007)
Martınez-Jeronimo&
Martınez-Jeronimo , 2007
Daphnia magna Water flea Crustaceans EC50 2d <24h 20 - - 64.256 Arambasic et al., 1995
Daphnia magna Water flea Crustaceans EC50 1d 21±1 - - 37.37 Lilius et al., 1994
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
22
Daphnia magnaa Water flea Crustaceans LC50 1d - - - - 28.421 Cowgill, 1987
Daphnia magnab Water flea Crustaceans LC50 1d - - - - 38.499 Cowgill, 1987
Oncorhynchus
mykiss
Rainbow
trout Fish EC50 3h 15 370 - 304.9 Lilius et al., 1994
Pimephales
promelas
Fathead
minnow Fish NOEC 7d 4-16h 25±1 - - 68.443 Pickering et al., 1996
Sreptocephalus
rubricaudatus - Shrimp LC50 1d 18h 25±0.5 - - 52.53 Crisinel et al., 1994
a Diet: Trout chow + alfalfa
b Diet: Chlamydomonas reinhardti Dangeard
c Broader range of concentration
d Small range of concentration
Table 7. Short-term and long-term toxicity data for MgCl2 Data in bold text represent the effect value used for derivation of the PNEC
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
23
Species
Scientific
Name
Species
Common
Name
Species Group Test Type Exposure
Duration
Age of
Species
Test
Temperature
(℃)
weight
(g)
Length
(cm) Value (mmol/L) Reference
Daphnia
magna Water flea Crustaceans LC50 1d <24h 20 - - 16.385 Mount et al., 1997
Daphnia
magna Water flea Crustaceans LC50 2d <24 20 - - 13.969 Mount et al., 1997
Pimephales
promelas
Fathead
minnow Fish LC50 1d 1-7d 25 - - 36.971 Mount et al., 1997
Pimephales
promelas
Fathead
minnow Fish LC50 2d 1-7d 25 - - 29.828 Mount et al., 1997
Pimephales
promelas
Fathead
minnow Fish LC50 3d 1-7d 25 - - 22.266 Mount et al., 1997
Table 8. Short-term and long-term toxicity data for CaCl2 Data in bold text represent the effect value used for derivation of the PNEC
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
24
Species Scientific
Name
Species Common
Name
Species
Group
Test
Type
Exposure
Duration
Age of
Species
Test Temperature
(℃)
weight
(g)
Length
(cm)
Value
(mmol/L) Reference
Daphnia magna Water flea Crustaceans LC50 1d <24h 20 - - 29.284 Mount et al.,
1997
Daphnia magna Water flea Crustaceans LC50 2d <24 20 - - 24.959 Mount et al.,
1997
Pimephales
promelas Fathead minnow Fish LC50 1d 1-7d 25 - - 60.009
Mount et al.,
1997
Pimephales
promelas Fathead minnow Fish LC50 2d 1-7d 25 - - 59.108
Mount et al.,
1997
Pimephales
promelas Fathead minnow Fish LC50 3d 1-7d 25 - - 41.718
Mount et al.,
1997
Table 9. Short-term and long-term toxicity data for K2SO4 Data in bold text represent the effect value used for derivation of the PNEC
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
25
Species Scientific
Name
Species
Common Name
Species
Group
Test
Type
Exposure
Duration
Age of
Species
Test Temperature
(℃)
weight
(g)
Length
(cm)
Value
(mmol/L) Reference
Daphnia magna Water flea Crustaceans LC50 1d <24h 20 - - 4.878 Mount et al.,
1997
Daphnia magna Water flea Crustaceans LC50 2d <24 20 - - 4.132 Mount et al.,
1997
Dreissena
polymorpha
Zebra mussel Bivalve LC50 1d - - - 1.5-2.0 0.643
Fisher et al.,
1991
Pimephales
promelas Fathead minnow Fish LC50 1d 1-7d 25 - - 5.68
Mount et al.,
1997
Pimephales
promelas Fathead minnow Fish LC50 2d 1-7d 25 - - 4.935
Mount et al.,
1997
Pimephales
promelas Fathead minnow Fish LC50 3d 1-7d 25 - - 3.902
Mount et al.,
1997
Table 10. Short-term and long-term toxicity data for Na2SO4 Data in bold text represent the effect value used for derivation of the PNEC
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
26
Species Scientific
Name
Species
Common Name
Species
Group
Test
Type
Exposure
Duration
Age of
Species
Test Temperature
(℃)
weight
(g)
Length
(cm) Value (mmol/L) Reference
Ceriodaphnia
dubia Water flea Crustaceans LC50 7d - - - - 14.425 Soucek, 2007
Daphnia magna Water flea Crustaceans LC50 2d 24h 20 - - 60.545
(59.067-61.742)
Meyer et al.,
1985
Daphnia magna Water flea Crustaceans LC50 2d 24h 20 - - 64.246 Arambasic et
al., 1995
Pimephales
promelas Fathead minnow Fish LC50 3d 96h - - -
107.010
(101.871-112.220)
Meyer et al.,
1985
Pimephales
Promelas Fathead minnow Fish LC50 4d 1-7d 20-25 - -
56.040
(47.873-70.402)
Mount et al.,
2007
Table 11. Short-term and long-term toxicity data for MgSO4 Data in bold text represent the effect value used for derivation of the PNEC
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
27
Species
Scientific
Name
Species
Common
Name
Species Group Test Type Exposure
Duration
Age of
Species
Test
Temperature
(℃)
weight
(g)
Length
(cm) Value (mmol/L) Reference
Daphnia
magna Water flea Crustaceans LC50 1d <24h 20 - - 19.607 Mount et al., 1997
Daphnia
magna Water flea Crustaceans LC50 2d <24 20 - - 15.12 Mount et al., 1997
Pimephales
promelas
Fathead
minnow Fish LC50 1d 1-7d 25 - - 38.466 Mount et al., 1997
Pimephales
promelas
Fathead
minnow Fish LC50 2d 1-7d 25 - - 29.161 Mount et al., 1997
Pimephales
promelas
Fathead
minnow Fish LC50 3d 1-7d 25 - - 23.428 Mount et al., 1997
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
28
4.2.5. CaCl2
- Data comparison
All data in Table 8 are short-term data sets. Data sets are obtained from two species
(Daphnia magna and Pimephales promelas).
For the crustaceans group, two days’ LC50 of Daphnia magna has the lowest value
(24.959 mmol/L).
For the fish group, three days’ LC50 of Pimephales promelas has the lowest value
(41.718 mmol/L).
The lowest value is shown in Crustaceans (24.959 mmol/L). So compared with fish
the Crustaceans are more sensitive to CaCl2. Longer exposure duration leads to lower
toxicity value.
- Calculation of PNECCaCl2
Data in Table 8 are all short-term LE(C)50 values from two trophic levels (fish and
crustaceans). This study assumes that the data from two trophic levels can present the
toxicity of CaCl2. Therefore a fixed assessment factor 1000 was used to calculate
PNECCaCl2.
PNECCaCl2 = 24.959 mmol/L / 1000 = 2.5×10-2
mmol/L
4.2.6. K2SO4
- Data comparison
All data in Table 9 are short-term data sets. Data sets are obtained from three species
(Daphnia magna, Pimephales promelas and Dreissena polymorpha).
For the crustaceans group, 2d LC50 of Daphnia magna has the lowest value (4.132
mmol/L).
For the fish group,3d LC50 of Brood Stock has the lowest value (3.902 mmol/L).
Data for Dreissena polymorpha is the lowest value in Table 9 (0.642 mmol/L).
Dreissena polymorpha are more sensitive to K2SO4 than Water fleas and fishes.
- Calculation of PNEC K2SO4
Data in Table 9 are all short-term LC50 values from two trophic levels. This study
assumes that the data from two trophic levels can present the toxicity of K2SO4.
Therefore a fixed assessment factor 1000 was used to calculate PNECK2SO4
PNEC K2SO4 = 0.643 mmol/L / 1000 = 6.43×10-4
mmol/L
4.2.7. Na2SO4
- Data comparison
All data in table 10 are short-term data sets. Data sets are obtained from three species
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
29
(Daphnia magna, Ceriodaphnia dubia and Pimephales promelas).
For the crustacean group, there are two kinds of data for Daphnia magna, the values
of these two kinds of data are similar (around 62 mmol/L). The toxicity value of
Ceriodaphnia dubia is lower than that of Daphnia magna (14.425 mmol/L).
For the fish group, the 4d LC50 test has a lower tolerance value (56.04 mmol/L),
while 3 hour LC50 test of Pimephales promelas has the highest tolerance value
(107.01 mmol/L), this may due to the short exposure duration.
The tolerance value of Ceriodaphnia dubia (14.425 mmol/L) is the lowest one in
Table 10, Ceriodaphnia dubia is the most sensitive species to Na2SO4.
- Calculation of PNECNa2SO4
All data in Table 10 are derived from short-term LE(C)50 values, which represents
two trophic level (crustaceans and fish). In this study, data from two trophic levels is
assumed to present the toxicity of Na2SO4. Therefore a fixed assessment factor of
1000 was used for calculating PNEC Na2SO4 value.
PNECNa2SO4 = 14.425 mmol/L / 1000 = 1.442×10-2
mmol/L
4.2.8. MgSO4
- Data comparison
All data in Table 11 are short-term data sets. Data sets are obtained from two species
(Daphnia magna and Pimephales promelas).
For the crustaceans group, two day toxicity test data of Daphnia magna are lower
than that in one day test.
For the fish group, longer exposure duration leads to lower toxicity value.
15.12 mmol/L is the lowest tolerance value in Table 11. Daphnia magna is more
sensitive to MgSO4 than Pimephales promelas.
- Calculation of PNECMgSO4
All data in Table 11 is short-term data which only presented in two trophic levels.
This study assumed that two trophic levels can present the toxicity of MgSO4.
Therefore a fixed assessment factor 1000 was used to calculate PNECMgSO4.
PNECMgSO4 = 15.12 mmol/L / 1000 = 1.512×10-2
mmol/L
4.2.9. PNEC values
All PNEC values are showed in Table 12.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
30
Table 12. PNEC value for each salt
Salt PNEC (mmol/L) Salt PNEC (mmol/L)
KCl 0.019 NaCl 0.51
MgCl2 0.014 CaCl2 0.025
K2SO4 0.00064 Na2SO4 0.014
MgSO4 0.015
From the table above, 0.00064 is the lowest value; this indicates of the salts studied
K2SO4 is the most toxic to freshwater species; K2SO4 can influence the freshwater
species in a quite low concentration.
4.2.10. Sensitivity of Daphnia magna to different salts
Each kind of salt considered in this study has at least one toxicity value of Daphnia
magna. Table 13 showed the lowest toxicity values of Daphnia magna for each salt.
Table 13. Sensitivity of Daphnia magna to salts
Salt Test Type Exposure
Duration
Effect Value
(mmol/L) Reference
KCl LC50 1d 9.9 Mount et al., 1997
NaCl LC50 1d 28.4 Cowgill, 1987
MgCl2 LC50 1d 14.01 Mount et al., 1997
CaCl2 LC50 2d 25.02 Mount et al., 1997
K2SO4 LC50 2d 4.13 Mount et al., 1997
Na2SO4 LC50 2d 60.54 Meyer et al., 1985
MgSO4 LC50 2d 15.1 Mount et al., 1997 1 [Cl
-] = 29.0 mmol/L
2 [Cl
-] = 50.0 mmol/L
3 [K
+] = 8.2 mmol/L
4 [Na
+] = 121 mmol/L
All the values presented are short term response. For the one day experiments
Daphnia magna is more sensitive to KCl. And for the two day experiments, Daphnia
magna is more sensitive to K2SO4. That indicated Daphnia magna is more sensitive to
K2SO4 and KCl than the other salts. Among the cations potassium seem to be more
toxic than the others. For the anions there is no trend.
4.2.11. General overview of PNEC values
Invertebrates appear to be more sensitive to salts than vertebrates. It may due to their
small size and short life span. Most salt toxicity data is also available for invertebrates
like Daphnia magna and Ceriodaphnia dubia.
The procedure for calculation of PNEC values using Fixed Assessment Factors values
is generally used for persistent compounds. Some Fixed assessment values are very
high like 100 and 1000. This will make the PNEC values very low and the RQ value
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
31
very high and this might lead to an overestimation of the risk.
4.3. Risk Characterization
4.3.1. RQ result for Chloride
Table 14 shows that all regions face a high risk of chloride from KCl, CaCl2 and
MgCl2 in freshwater since all RQmaxs values are above 1 and only in a few regions’
RQmins values are lower than 1 (Table 14). Chloride in NaCl has risk to most of the
regions except in the regions of Gävleborg and Jämtland.
The risk of chloride in NaCl is lower than for other forms of chloride.
Gotland has the highest risk of chloride.
4.3.2. RQ results for Sulfate
Table 15 shows all RQmaxs values of sulfate are higher than 1, all regions have risks of
sulfate in freshwater. Only a few RQmins values are lower than 1. The concentration of
sulfate in Sweden varies significantly which indicates some regions have risks of
sulfate while some have no risks of sulfate (eg. there is no risk of sulfate to parts of
the regions of Dalarna and Norrbotten).
The risk of sulfate in Na2SO4 is lower than that of other sulfate salts.
The region of Västerbotten suffers the highest risk of sulfate followed by Gotland.
4.3.3. RQ results for Sodium
In Table 16, sodium concentrations in almost all regions’ are quite high which means
the freshwater ecosystem in Sweden have a high risk of sodium.
When considering the sodium concentration in Na2SO4 form, just in a few regions like
Värmland, Dalarnas, Gävleborg, Jämtland, Västerbotten and Norrbotten there is no
risks. Considering the sodium concentration in NaCl form, most regions are suffering
the risk of sodium except Halland, Örebro, Dalarna, Jämtland and Norrbotten.
In general, the risk of sodium shown in NaCl form is lower than that for the other
sodium salts.
Gotland has the highest risk of sodium.
4.3.4. RQ results for Potassium
In Table 16, the concentrations of potassium in all regions show risks to freshwater
ecosystems, except some parts of some regions with no potassium compounds in
freshwater ecosystem.
In general, the RQmins values of potassium concentration in potassium chloride form
present lower risk to the freshwater ecosystem than potassium sulfate.
Gotland has the highest risk of potassium.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
32
4.3.5. RQ results for Magnesium
In Table 17, the concentrations of magnesium in Sweden show a risk in most of the
places in Sweden because there is only few RQmin values of MgCl2 and MgSO4 that
are lower than 1 (RQmin values below 1 occur in the following regions: Västra
Götaland, Värmland, Örebro, Västmanland, Dalarna, Gävleborg, Västernorrland,
Jämtland, Västerbotten and Norrbotten).
The risks of magnesium in MgCl2 form and MgSO4 form are similar.
Gotland presents the highest risk of magnesium in the freshwater ecosystem.
4.3.6. RQ results for Calcium
In Table 17, when considering the calcium concentration in CaCl2 form, the
concentration of calcium is a risk to most places of Sweden since there are only a few
RQmin values in some places in the regions of Halland, Västra Götaland, Dalarna,
Jämtland, Västerbotten and Norrbotten that are below 1.
Skåne has the highest risk of calcium in freshwater ecosystem followed by
Västerbotten and Gotland.
4.3.7. General overview of RQ values
- The RQ values for sulfate are much higher than the other toxic compound; it
indicates that the concentration of sulfate in Swedish freshwater is much
higher than the most sensitive freshwater species can tolerate.
- Most RQ value are above 1, the reason could be:
a. The data of effect assessments are limited to two trophic levels, this
causes the fix assessment factor to be quite high, then the calculated
PNEC is quite low, and the generated RQ is quite high. It is also possible
that the fixed assessment factors which generally are used for persistent
chemicals might not be suitable for risk assessment of salts.
b. Using the ion concentration in salt as PNEC value to calculate RQ has
some limitations to present the real risk of salt in the Swedish freshwater
ecosystem. However, the RQ value can still show which compound that
is most toxic to freshwater organisms.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
33
Table 14. RQ values for chloride
RQs for chloride
KCl NaCl MgCl2 CaCl2
Region max min max min max min max min
Stockholm 574.3 2.9 41.4 0.2 380.5 1.9 212.9 1.1
Uppsala 51.5 2.7 3.7 0.2 34.1 1.8 19.1 1.0
Södermanland 40.5 2.5 2.9 0.2 26.8 1.7 15.0 0.9
Östergötland 42.5 3.0 3.1 0.2 28.2 2.0 15.8 1.1
Jönköping 31.3 3.7 2.3 0.3 20.8 2.4 11.6 1.4
Kronoberg 49.6 6.2 3.6 0.4 32.9 4.1 18.4 2.3
Kalmar 88.5 4.1 6.4 0.3 58.7 2.7 32.8 1.5
Gotland 5190.2 9.2 374.3 0.7 3438.7 6.1 1924.6 3.4
Blekinge 26.6 8.4 1.9 0.6 17.6 5.6 9.9 3.1
Skåne 327.3 6.8 23.6 0.5 216.9 4.5 121.4 2.5
Halland 25.4 6.2 1.8 0.4 16.8 4.1 9.4 2.3
Västra Götaland 3556.9 3.6 256.5 0.3 2356.6 2.4 1318.9 1.3
Värmland 51.2 0.9 3.7 0.1 33.9 0.6 19.0 0.3
Örebro 15.4 1.8 1.1 0.1 10.2 1.2 5.7 0.7
Västmanland 42.6 1.8 3.1 0.1 28.2 1.2 15.8 0.7
Dalarna 13.0 0.2 0.9 0.0 8.6 0.1 4.8 0.1
Gävleborg 30.2 0.4 2.2 0.0 20.0 0.3 11.2 0.2
Västernorrland 29.4 0.6 2.1 0.0 19.5 0.4 10.9 0.2
Jämtland 5.4 0.2 0.4 0.0 3.6 0.1 2.0 0.1
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
34
Västerbotten 217.0 0.2 15.7 0.0 143.8 0.1 80.5 0.1
Norrbotten 14.3 0.2 1.0 0.0 9.4 0.1 5.3 0.1
max 5190.2 9.2 374.3 0.7 3438.7 6.1 1924.6 3.4
min 5.4 0.2 0.4 0.0 3.6 0.1 2.0 0.1
*All data in bold text have a RQ above 1 and there is therefore a risk to the freshwater ecosystem.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
35
Table 15. RQ values for sulfate
RQs for sulfate
K2SO4 Na2SO4 MgSO4
Region max min max min max min
Stockholm 1049.4 23.7 46.8 1.1 89.3 2.0
Uppsala 1612.8 7.8 71.9 0.3 137.2 0.7
Södermanland 217.7 21.0 9.7 0.9 18.5 1.8
Östergötland 937.4 12.8 41.8 0.6 79.7 1.1
Jönköping 374.0 12.1 16.7 0.5 31.8 1.0
Kronoberg 126.0 22.6 5.6 1.0 10.7 1.9
Kalmar 206.8 28.8 9.2 1.3 17.6 2.4
Gotland 3787.7 72.3 168.8 3.2 322.2 6.2
Blekinge 129.9 19.8 5.8 0.9 11.0 1.7
Skåne 1187.8 19.4 52.9 0.9 101.0 1.7
Halland 145.4 27.6 6.5 1.2 12.4 2.3
Västra Götaland 2562.2 9.3 114.2 0.4 217.9 0.8
Värmland 50.9 4.3 2.3 0.2 4.3 0.4
Örebro 192.8 10.5 8.6 0.5 16.4 0.9
Västmanland 190.1 9.3 8.5 0.4 16.2 0.8
Dalarna 2213.1 2.7 98.6 0.1 188.2 0.2
Gävleborg 242.2 3.9 10.8 0.2 20.6 0.3
Västernorrland 85.1 6.6 3.8 0.3 7.2 0.6
Jämtland 224.3 3.1 10.0 0.1 19.1 0.3
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
36
Västerbotten 9270.6 2.3 413.2 0.1 788.5 0.2
Norrbotten 1039.3 1.9 46.3 0.1 88.4 0.2
max 9270.6 23.7 413.2 1.1 788.5 2.0
min 50.9 1.9 2.3 0.1 4.3 0.2
*All data in bold text have a RQ above 1 and there is therefore a risk to the freshwater ecosystem.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
37
Table 16. RQ values for sodium and potassium
RQs for sodium RQs for potassium
NaCl Na2SO4 KCl K2SO4
Region Max min max min max min max min
Stockholm 15.3 0.1 272.5 2.4 13.5 0.3 193.9 4.7
Uppsala 2.4 0.2 42.9 3.4 8.2 0.5 117.6 7.8
Södermanland 1.5 0.1 26.0 2.3 5.4 0.3 77.9 4.7
Östergötland 1.6 0.1 27.7 2.6 7.3 0.5 105.1 7.0
Jönköping 1.7 0.2 29.4 2.7 5.8 0.5 84.1 7.0
Kronoberg 1.8 0.3 31.6 4.9 4.8 0.3 68.5 4.7
Kalmar 2.7 0.2 47.5 3.6 8.8 0.5 126.2 7.8
Gotland 107.0 0.3 1904.4 6.1 98.9 0.9 1425.2 13.2
Blekinge 1.2 0.4 21.3 6.9 3.3 0.6 47.5 9.3
Skåne 8.3 0.3 148.4 6.0 9.3 0.7 134.0 10.1
Halland 0.9 0.2 15.9 4.3 7.1 0.4 102.0 5.4
Västra Götaland 81.3 0.1 1445.8 2.6 70.9 0.3 1021.8 3.9
Värmland 1.8 0.0 31.2 0.9 2.8 0.1 40.5 1.6
Örebro 0.5 0.1 8.3 1.4 4.3 0.2 62.3 3.1
Västmanland 1.4 0.1 25.1 1.6 5.9 0.2 85.7 3.1
Dalarna 0.9 0.0 16.8 0.3 23.4 0.0 338.0 0.0
Gävleborg 1.6 0.0 28.6 0.8 11.0 0.2 158.1 2.3
Västernorrland 1.1 0.1 19.3 1.0 5.0 0.1 71.7 1.6
Jämtland 0.2 0.0 4.2 0.3 2.1 0.0 30.4 0.0
Västerbotten 6.0 0.0 106.3 0.2 8.4 0.0 121.5 0.0
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Norrbotten 0.9 0.0 16.2 0.1 7.9 0.0 113.7 0.0
max 107.0 1.8 1904.4 31.8 98.9 0.9 1425.2 13.2
min 0.2 0.0 4.2 0.1 2.1 0.0 30.4 0.0
*All data in bold text have a RQ above 1 and there is therefore a risk to the freshwater ecosystem.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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Table 17. RQ values for magnesium and calcium
RQs for magnesium RQs for calcium
MgCl2 MgSO4 CaCl2
Region max min max min max min
Stockholm 76.1 1.6 70.3 1.5 107.8 2.1
Uppsala 40.3 2.9 37.3 2.7 98.4 5.0
Södermanland 17.4 1.6 16.1 1.5 26.5 1.6
Östergötland 19.4 1.4 17.9 1.3 107.0 1.3
Jönköping 16.6 1.5 15.3 1.4 43.7 1.4
Kronoberg 9.5 2.1 8.8 2.0 13.6 1.1
Kalmar 17.8 2.6 16.4 2.4 19.7 2.4
Gotland 523.1 6.5 483.3 6.0 120.1 39.1
Blekinge 8.6 2.9 8.0 2.7 19.4 2.5
Skåne 82.8 2.0 76.5 1.9 130.8 1.4
Halland 17.4 1.5 16.0 1.4 13.7 0.5
Västra Götaland 372.4 0.9 344.0 0.9 94.2 0.3
Värmland 6.7 0.5 6.2 0.4 14.8 0.6
Örebro 8.5 1.0 7.8 0.9 51.4 0.8
Västmanland 16.1 0.9 14.8 0.8 26.8 0.7
Dalarna 59.4 0.1 54.9 0.1 96.2 0.1
Gävleborg 14.0 0.4 12.9 0.3 46.5 0.6
Västernorrland 10.0 0.6 9.2 0.6 13.0 0.7
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Jämtland 20.1 0.1 18.6 0.1 71.3 0.1
Västerbotten 215.8 0.2 199.4 0.2 128.6 0.1
Norrbotten 25.2 0.1 23.2 0.1 61.1 0.1
max 523.1 6.5 483.3 6.0 130.8 31.9
min 6.7 0.1 6.2 0.1 13.0 0.1
*All data in bold text have a RQ above 1 and there is therefore a risk to the freshwater ecosystem.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
41
5. Conclusion
The concentration of cations and anions in Gotland is quite high compared to
other regions.
Most toxicity data found was short term responses for crustaceans like Daphnia
magna.
Invertebrates appear to be more sensitive to salts than fish.
The most sensitive endpoint was found for Dreissena polymorpha in short term
test where LC50 for K2SO4 was 0.643 mmol/L. The lowest LC50 values were also
in general obtained for K2SO4.
Daphnia magna was more sensitive to K2SO4 and KCl than to the other salts.
Most RQ values in Swedish freshwater were above 1 and showed risk for the
freshwater ecosystem.
The risk of sulfate to Swedish freshwater ecosystem is much higher than the risk
of other toxic ions.
Gotland had the highest RQ values.
Very high risk quotients were obtained for many Swedish freshwater ecosystems
even though many of them have a high biodiversity. The reason for this is unclear
but it could be due to the size of the fixed assessment factors which in general are
used for persistent pollutions but might not be suitable for salts. Another plausible
explanation is that the treatment of the effect data to fit the exposure data is not
adequate and other methods have to be explored.
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
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Acknowledgement
This thesis could not be finished without the help and support of many people who are
gratefully acknowledged here.
At the very first, I’m honored to express my deepest gratitude to my dedicated
supervisor, Prof. Sylvia Waara, with whose able guidance I could have worked out
this thesis. She has offered me valuable ideas, suggestions and criticisms with her
profound knowledge in research experience. Her patience and kindness are greatly
appreciated. Besides, she always puts high priority on our dissertation writing and is
willing to discuss with me anytime she is available. I have learnt from her a lot not
only about dissertation writing, but also the professional ethics. I’m very much
obliged to her efforts of helping me complete the dissertation.
What’s more, I wish to extend my thanks to Prof. Stefan Weisner. I learned how to
write a good report in his class. This gave me an idea about how to write this thesis.
At last but not least, I would like to thank my family for their support all the way from
the very beginning of my study. I am thankful to all my family members for their
thoughtfulness and encouragement.
JIANG Huan
2011. 5. 25
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
43
References
Arambasic M. B., Bjelic S., Subakov G. (1995) Acute toxicity of heavy metals
(Copper, Lead, Zinc), Phenol and Sodium on Allium cepa L., Lepidium sativum L.
and Daphnia magna St.: Comparative investigations and the practical
applications. Water Research 29 (2): 497-503
Berezina N. A. (2003) Tolerance of freshwater invertebrates to changes in water
salinity. Russian Journal Ecology 34 (4): 261-266
Boeuf G. & Payan P. (2001) How should salinity influence fish growth?
Comparative Biochemistry and Physiology Toxicology & Pharmacology 130 (4):
411-23
Blasius B. J. & Merritt R.W. (2002) Field and laboratory investigations on the
effects of road salt (NaCl) on stream macroinvertebrate communities.
Environmental Pollution 120: 219-231
Cowgill U. M. (1987) Critical analysis of factors affecting the sensitivity of
zooplankton and the reproducibility of toxicology test results. Water Resaerch 21
(12): 1453-1462
Crisinel A., Delaunay L., Rossel D., Tarradellas J (1994) Cryst – based
ecotoxicological tests using anostracans: Comparison of two species of
Streptocephalus. Environmental Toxicology and Water Quality 9: 317-326
Degraeve G. M., Cooney J. D., Marsh B. H. (1992) Variability in the performance
of the 7-D Ceriodaphnia dubia survival and reproduction test: An intra- and
interlaboratory study. Environmental Toxicology and Chemistry 11: 851-866
Dumont H. J., Adriaens E. (2009) Experimental hybridization of two African
Streptocephalus species (Crustacea, Branchiopoda; Anostrace). Current Science
96: 88-90
Dunlop J. E., Horrigan N., McGregor G., Kefford B. J., Choy S., Prasad R. (2008)
Effect of spatial variation on salinity tolerance of macroinvertebrates in Eastern
Australia and implications for ecosystem protection trigger values.
Environmental Pollution 151: 621-630
European Commission (2003) Technical Guidance Document on Risk
Assessment Part 2, EUR 204 18 EN/2
Fisher S. W., Stromberg P., Bruner K. A., Boulet L. D. (1991) Molluscicidal
activity of potassium to the zebra mussel, Dreissena polymorphia: toxicity and
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
44
mode of action. Aquatic Toxicology 20: 219-234
Fishbase (2010) Carassius auratus auratus
http://www.fishbase.org/summary/speciessummary.php?id=271 (visiting date:
2011.04.05)
Harmon S. M., Specht W. L., Chandler G. T. (2003) A comparison of the
Daphnids Ceriodaphnia dubia and Daphnia ambigua for their utilization in
routine toxicity testing in the Southeastern United States. Archives of
Environmental Contamination and Toxicology 45: 79-85
Hart B. T., Bailey P., Edward R., Hortle K., James K., McMahon A., Meredith C.,
Swadling K. (1991) A review of the salt sensitivity of the Australian Freshwater
biota. Hydrobiologia 210: 105-144
Lazorchak H. M., Smith M. E (2007) Rainbow trout (Oncorhynchus mykiss ) and
Brook trout (Salvelinus fontinalis) 7-day survival and growth test method.
Archives of Environmental Contamination and Toxicology 53: 397-405
Lilius H., Isomaa B., Holmstrom (1994) A comparison of the toxicity of 50
reference chemicals to freshly isolated rainbow trout hepatocytes and Daphnia
magna. Aquatic Toxicology 30: 47-60
Martınez-J. F. & Martınez-J. L. (2007) Chronic effect of NaCl salinity on a
freshwater strain of Daphnia magna Straus (Crustacea: Cladocera): A
demographic study. Ecotoxicology and Environmental Safety 67: 411-416
MBL Aquaculture (2005) Daphnids
http://www.mblaquaculture.com/content/organisms/daphnids.php (visiting date:
2011.04.05)
Meyer J. S., Sanchez D. A., Brookman J. A., Mcwhorter D. B., Bergman H. L.
(1985) Chemistry and aquatic toxicity of raw oil shale leachates from Piceance
basin, Colorado. Environmental Toxicology and Chemistry 4: 559-572
Montana Field Guide (2011) Fathead Minnow
http://fieldguide.mt.gov/detail_AFCJB32020.aspx (visiting date: 2011.04.05)
Mount, D. R., D. D. Gulley, J. R. Hockett, T. D. Garrison, and J. M. Evans (1997)
Statistical models to predict the toxicity of major ions to Ceriodaphnia dubia,
Daphnia magna and Pimephales promelas (Fathead Minnows). Environmental
Toxicology and Chemistry 16 (10): 2009-1019
Myers G. S. (1949) Salt-tolerance of fresh-water fish groups in relation to
zoogeographical problems
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
45
http://www.animal-ecology.info/salt_tolerance_of_freshwater_fish.htm (visiting
date: 2011.07.20)
National Atlas of the United States (2005) Zebra Mussels
http://www.nationalatlas.gov/articles/biology/a_zm.html (visiting date:
2011.04.05)
National Geographic (2011) Rainbow Trout
http://animals.nationalgeographic.com/animals/fish/rainbow-trout/ (visiting date:
2011.04.05)
Nielsen D.L., Brock M. A., Rees G. N., Baldwin D. S. (2003) Effects of
increasing salinity on freshwater ecosystem in Australia. Australian Journal of
Botany 51: 655-665
Paulson N., Hatch J. T. (2011) Fathead Minnow
http://www.lakesuperiorstreams.org/understanding/fatheadminnow.html (visiting
date: 2011.04.05)
Pickering Q. H., Lazorchak J. M., Winks K. L. (1996) Subchronic sensitivity of
one-, four-, and seven-day-old Fathead Minnow (Pimephales promelas) larvae to
five toxicants. Environmental Toxicology and Chemistry 15 (3): 353-359
Soucek D. J. (2007) Bioenergetic effects of sodium sulfate on the freshwater
crustacean, Ceriodaphnia dubia. Ecotoxicology 16: 317-325
Swedish Environmental Protection Agency (2010) Riksinventering 2000,
vattenkemi i sjöar
http://info1.ma.slu.se/ri/www_ri.acgi$Project?ID=Intro
(visiting date: 2011.04.05)
Tietge J. E., Hockett J. R., Evans J. M. (1997) Major ion toxicity of six produced
waters to three freshwater species: application of ion toxicity models and
procedures. Environmental Toxicology and Chemistry 16 (10): 2002-2008
Threader R. W. & Houston A. H. (1983) Use of NaCl as a reference toxicant for
Goldfish, Carassius auratus. Canadian Journal of Fisheries and Aquatic Sciences
40: 89-92
Trout Unlimited (2011) Brook Trout
http://www.tu.org/conservation/eastern-conservation/brook-trout (visiting date:
2011.04.05)
Utz L. R. P., Bohrer M. B. C. (2001) Acute and chronic toxicity of potassium
Ecological Risk Assessment of Salts in the Swedish Freshwater Ecosystem
46
chloride (KCl) and potassium acetate (KC2H3O2) to Daphnia similis and
Ceriodaphnia dubia (Crustacea; Cladoccera). Bulletin of Environmental
Contamination and Toxicology 66: 379-385
United State Environmental Protection Agencya (2010) Freshwater Ecosystem
http://www.epa.gov/bioindicators/aquatic/freshwater.html (visiting date:
2011.04.05)
United State Environmental Protection Agencyb (2011) ECOTOX Database
http://cfpub.epa.gov/ecotox/ (visiting date: 2011.01.11)
Xie B., Lv Y. B., Hu C., Liang S. B., Tang Y., Lu J. (2010) Landfill leachate
pollutant removal performance of a novel biofilter packed with mixture medium.
Bioresource Technology 101: 7754-7760