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Appendix 1.23 Impact Assessment on River Feale Increased Effluent

Sulphate

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Assessment of the Impact of

Increased Effluent Sulphate Concentrations from

Kerry Ingredients on the River Feale

#Listowe - County Kerry

(April 2005)

.

Commissioned by: Kerry Ingredients plc (Li&owel) Carried out by: Aquatic Services Unit, UCC (April 2005)

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Table of Contents

1 INTRODUCTION & BRIEF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2 REVIEW PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3 hERVIEW OF LITERATURE REVIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

4 OVERVIEW OF INTERNATIONAL GUIDELINES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

5 PROJECTED SULPHATE CONCENTRATIONS IN THE RIVER FEALE 7

a 6 DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..*....................................... 12

7 SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

8 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

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1 Introduction & Brief

Kerry Ingredient plc Listowel, commissioned the Aquatic Services Unit to assess the implications for the River Feale of raising the concentration of sulphate in their Listowel Plant’s final. effluent to 750mg/l, SO+ Sulphate in the waste stream is derived from the oxidation of sulphide from the digestor and sulphate derived from the final treatment process. This report encompasses the review of scientific literature specifically to, assess the effects of elevated sulphate levels on freshwater aquatic life, and investigates existing international sulphate guidelines and limits. The information is then reviewed with reference to a sulphate- rich industrial effluent discharging to the River Feale. The waters of the River Feale are designated salmonid habitat.

2 Review Procedure

To assess the effects of sulphate enrichment on the aquatic communities within the River Feale, the following approach was adopted:

1) Review of scientific literature and relevant reports regarding the toxicity of sulphates to freshwater aquatic organisms.

2) Review of relevant national and international guidelines pertaining to sulphates in surface waters.

3) Calculation of the projected sulphate concentration range within the River Feale during low flow months (May - October) for the years 1976 - 2001, based on a maximum effluent sulphate concentration of 750 mg/l.

4) Analysis of the implications of sulphate enrichment in the River Feale.

3 Overview of Literature Review

A detailed review of the scientific literature pertaining to sulphate toxicity to aquatic organisms (plants, invertebrates and fish) is in Appendix 1. The main review of international guidelines and emission limits is in Appendix 2. Brief overviews of the important aspects of these reviews follow.

3.1 Toxicity

Sulphates occur naturally in surface freshwaters and are generally not believed to be toxic to aquatic life except at very high concentrations. Because of this the effects of sulphates on aquatic organisms are not widely studied, and the volume of information within the scientific literature is relatively scarce, compared to other substances.

A few studies have reported sulphate toxicity to some aquatic organisms (i.e., fish and aquatic mosses) at or below 100 mg/l Sod. However, in one particular case related to the toxicity to aquatic moss, there was some question as to the reliability of these data for a number of reasons, such as poor test procedures, failure to report test procedure information, arid

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possible calculation errors (Singleton, 2000). Thus, the lowest corroborated sulphate effect level reported in the literature was 205 mg/l, to a species of freshwater amphipod in softwater.

In general, toxicity of sulphates increases with decreasing water hardness.

In drinking water (humans and livestock), sulphates in excess of 5OOmg/l can exert purgative and/or laxative effects (Singleton, 2000).

One problem associated with sulphate-enrichment is that dissolved sulphate may be reduced to sulphide, and volatilized to air as hydrogen sulphide. This can cause noxious odours where sulphate concentrations are high and dissolved oxygen levels are low (EPA Ireland, 2001). Such effects are extremely unlikely to occur in the Feale given it’s very well oxygenated status.

3.2 International Effluent Discharge Limits

International limits for discharge sulphates in effluents to surface waters vary widely, with a reported range of 150 mg/l to 2000 mg/l SO.+ (Table 1, Appendix 2). The rationales behind these effluent concentration limits are not discussed in the report and no further explanations could be located.

Only one scientific report regarding a sulphate discharge in Ireland was located. No specific guideline for maximum sulphate concentration in discharges could be found for Irish waters.

3.3 International Receiving Water Guidelines

Table 1 summarises guidelines for sulphates that have been set specifically for the protection of aquatic life. Most jurisdictions, including Ireland have limits set in respect of waters intended for drinking water abstraction and finished drinking water, but not for aquatic life protection.

In Ireland the Mandatory Limit Value for sulphates in Al, A2 and A3 surface waters intended for abstraction for drinking water supply is 200 mg/l SOa, implemented in Ireland by the Surface Water Regulations (1989) (EPA Ireland, 2001).

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Table 1 Maximum sulphate concentration in surface waters for aquatic life protection.

Canada

Quebec

Guideline for Sulphates Reference

(mg/l)

100 (not to be exceeded) Singleton, 2000

50 (alert level for aquatic mosses)

Acute: 300 Environnement

Chronic: not set Quebec (website)

4 Overview of International Guidelines

4.1 Specific Considerations For The River Feale

Foremost, it is clear from the literature that sulphates are most toxic to aquatic organisms in soft waters. Aquatic mosses and a freshwater amphipod have shown especially low tolerance to sulphates in soft water conditions in laboratory studies. Mosses of the genus Fontinalis are present in the Feale, as are amphipods of the genus Gammarus (though not in high abundance).

Work undertaken by ASU on the Feale in 1996 revealed water hardness in the range of 38 to 52 mg/l (as CaC03) from July to September in the study reach. By coupling these 1996 data with EPA monitoring data from the area it is inferred that a median of approximately 30 to 34 mg/l for water hardness can be expected in the Feale system. This indicates that soft water conditions predominate in the Feale.

Given the soft nature of the water and the reported sensitivity of the aquatic moss Fontinalis, it is possible that existing sulphate exposures in the Feale may already be impacting this species. From the annual biological monitoring we know that Fontinah is common above the discharge point, and is also recorded at Site 2 i.e. 600-700m downstream of the discharge and again at Site 3 (Scartlea Weir).

The Feale is an important salmonid fishery and there is no evidence that the current discharge is adversely impacting it. This is expected as salmonid species are known to be very tolerant of sulphate (see Appendix 1). A fish stock survey undertaken on the Feale in 2001 found that juvenile salmon densities were among the highest recorded for an Irish river and that numbers had increased over previous years (CFB, 2001).

4.2 Review of Guideline Rationale

Because the literature on sulphate toxicity is quite scarce, we have relied on the only comprehensive guideline rationale available, which comes from the Canadian Water Quality Guidelines for the Protection of Aquatic Life (CCME, 1999). The following recommendations for sulphate limits in the River Feale are discussed in reference to these.

Canadian guidelines are based on toxicity data for the most sensitive aquatic species, and therefore act as benchmarks to protect 100% of aquatic life species, 100% of the time. A

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guideline concentration for sulphate (in surface waters) of lOOmg/l SO,, which must not be exceeded at any time, is due to the following factors:

Sensitivity of North American striped bass (Morone saxitilis) larvae. (4-day LCO of lOOmg/l Sod, and 4-day LCso of 25Omg/l SO4)

2)

3)

Sensitivity of the amphipod, HyaZeZZa (4-day LC5a in soft water of 205mg/l Sod).

Apparent sensitivity of aquatic mosses. Mortality is reported by Frahm (1975, in Singleton, 2000) in Fontindis antipyretica after l-week exposure to 100 mg/l SO,. Thus, an additional “alert level” of 50 mg/l SO, is set for aquatic moss populations to be checked on an occasional basis.

4) Anecdotal evidence that elevated sulphate levels (average of 71 mg/l Sod, range 27.7-189 mg/l SO ) 4 can stimulate large sulphur bacteria growths, which can cover substrates and adversely affect macro-invertebrate communities and river ecology.

With regard to these we can observe the following from an Irish context:

1)

2)

3)

4)

Striped bass is not represented in the Irish fauna but may serve as an indicator for perch species {Perca fluviatilis), however the relevant stretch of the Feale is not considered significant habitat for perch.

The amphipod, Hyalda is not present in Irish freshwaters, and there are reports that HyaZeZZa may be able to acclimatise to higher levels of sulphates. But, it is possible that all freshwater amphipods are susceptible to sulphate toxicity in soft water conditions.

Aquatic mosses of the genus Fontinalis are likely to be the most sensitive to sulphates in the River Feale. It is important to note, that the work by Frahm (1975) has not been replicated, and there is still conflicting evidence over the response of aquatic mosses to sulphate enrichment. The author of the Canadian guidelines for sulphates recommends that further research be carried out to check on the apparent sensitivity of Fontinalis.

There have been no scientific studies to ascertain the conditions that stimulate sulphur bacteria growths.

In short, the Canadian threshold value for sulphates may be overly stringent for application to Irish freshwaters. However, there are two constraining factors upon which a conservative set of guidelines is recommended for the Feale as follows:

1) The apparent sensitivity of Fontinalis,

2) The fact that there is no specific toxicity data for resident invertebrate species in the Feale, and that soft water conditions are known to exacerbate sulphate toxicity in some invertebrates,

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a Furthermore, the ELJ Mandatory Limit Value of 200 mg/l SO4 in surface waters intended for abstraction should not be exceeded in any sample taken from the River Feale downstream of the discharge point because the site of abstraction for Listowel public water supply is located at Scartlea Weir - downstream of the Kerry Ingredients effluent discharge.

4.3 Recommended Guideline for Sulphates in the River Feale

The effluent sulphate concentration should be limited to a level such that:

i. Annual average in-stream concentrations do not exceed 100 mg/l SO+

ii. No single downstream sample contains greater than 200 mg/l SO,.

iii. Sulphate levels rarely persist above the lOOmg/l threshold in “worst case” scenarios.

iv. Where there is persistent exposure to sulphate concentrations in excess of 50 mg/l, the health aquatic moss populations are monitored.

5 Projected Sulphate Concentrations in the River Feale

Predicted sulphate concentrations in the River Feale have been calculated based on a projected effluent sulphate concentration of 750 mgfl and known flow data for the years 1976

’ to 2001. Calculations are made for the low flow (summer) months of May to October in those years.

5.1 Effluent and Abstraction Parameters

For the purpose of this assessment, background sulphate concentrations in the Feale (upstream of the Kerry Ingredients plant) was put at 6 mg/l, based on data obtained from annual monitoring of the Feale in 2004 for Kerry Ingredients. This is because of the absence of any data for the Feale, at Listowel, upstream of the discharge. Tables 2 and 3 show the effluent parameters upon which further calculations are made.

Table 2 Kerry Ingredients effluent discharge rates

Parameter Unit Volume

Maximum Daily Discharge m3/day 12,000

Average Daily Discharge m3/day 8,000

Range m3/day 2,500 - 12,000

Maximum Hourly Discharge m3/hr 400

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Range m31hr 100 - 400

Table 3 Kerry Ingredients water abstractions / sources

Parameter Unit

Maximum Daily Abstraction m3/day (license limit)

Average Daily Abstraction m3fday

(actual)

Volume

10,000

9000

Well Abstraction m3Jday 360

Average Rainwater Flow m3 /day 400

Water from Product m31day 2240

5.1 General Equation For Calculating Projected Sulphate Concentration

In calculating the likely increase in sulphate in the Feale, based on an increase in effluent concentration to 75Omg/l, worst case scenarios were generally chosen, i.e., highest effluent discharge rates and concentrations. The general equation is as follows:

(upstream flow B x upstream sulphate concentration + effluent flow x max effluent concentr&tion) divided by (upstream flow A + water from product)

(Note: Upstream Flow A is the river upstream of any abstraction, Upstream flow B is the river flow downstream of the abstraction point but upstream of the effluent discharge point)

5.2 Results of Concentration Projections for the River Feale

The results of the projected sulphate concentration calculations are in Tables 4, 5 and 6 showing, respectively, monthly averages, monthly instantaneous maxima and maximum 4- day averages. Values exceeding both 50 mg/l SO4 and 100 mgfl SO4 have been highlighted.

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Table 4 Monthly average sulphate (mg/l, SOa) in the River Feale for the montlk of May to October based on 1976-2001 flow data and a projected effluent s&hate concentration of 750 mg/l. Figures in bold are H%ng/l.

1998 31 13 13 15 11 8

1999 21 52 30 18 9 12

2000 15 17 17 13 11 8

2001 31 43 33 23 27 10

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Table 5 Monthly maximum sulphate (mg/l, Sod) in the River Feale for the months of May to October based on minimum instantaneous flows in each month for the period 1976-2001 and a projected effluent sulphate concentration of 750mg/l and an effluent volume of 12,000m3/day. Figures in bold are > lOOmg/l.

2001 55 72 1 81 75 67 1 24

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Table 6 Maximum &average sulphate (mg/l, SO4) in the River Feale for those months between May and October which had a maximum instantaneous sulphate value in any month of >50 mg/l. Based on 1976-2001 flow data and a projected effluent sulphate concentration of 750 mg/l and 12,000m3/day discharge. Figures bold are > lOOmg/l.

2000

2001 70 75 72 65

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6 Discussion

The analysis in this section determines whether an effluent sulphate concentration of 750 mg/l is acceptable in meeting the recommended guideline values presented in subsection 4.3.

Table 4 shows that the projected monthly average sulphate values are low. During the 24- year period only one estimated monthly average value was above the 100 mg/l SO, threshold, while several monthly average values were above the 50 mg/l SO, threshold for checking on aquatic moss populations.

Table 5 shows that instantaneous flow rates have been low enough to produce monthly maxima that are above the 100 mg/l SO, threshold on frequent occasions, although these exceedences are not particularly significant, with only six instances when the figure was double or more. The highest projected 4-day averages for each month (Table 6) show that sulphate levels would be expected to exceed 100 mg!l threshold in just a few cases cases. The highest projected 4-day averages concentrations were 276,270 and 270 mg/l SO, and (in July 1989, July 1984 and August 1976). The persistence of elevated levels of sulphate may be significant, given that after one week’s exposure to 100 mg/l SO,, mortality has been reported in Fontinalis. However, these short periods of elevated concentrations are rare in occurrence, and are not considered to pose a significant threat to the aquatic mosses of the Feale. Furthermore, for reasons already explained the 100 mg/l limit may be overly stringent.

The highest monthly maximum calculated (based on lowest instantaneous flow) is 367 mg/l SO4 (August 1976). This value exceeds the statutory limit of 200 mg/l for water abstraction but this concentration is not persistent, as indicated by the monthly 4-day average (252 mg/l Sod) in the same month.

To judge from the data presented one could expect that on average, the monthly maximum 4- day average concentration of sulphate in the river would exceed lOOmg/l every 2-3 years but only significantly exceed it (>2OOmg/l) on average about once in every decade.

7 Summary

It must be recognised that the 100 mg/l SO, threshold may be overly stringent for Irish waters, as the value is, essentially, based on non resident species. Nevertheless, because of the soft water conditions and presence of the aquatic moss Fontinalis, the value provides a fair guideline to protect perhaps the most vulnerable species within the Feale. The recommendations recognise that the value may be conservative, by allowing the 100 mg/l SO, threshold to be exceeded for short periods on relatively infrequent occasions.

Indications are that the projected sulphate concentration data for the Feale (based on 750 mg/l SO4 in effluent) fulfil the established recommendations with the exception of one value, summarised as follows:

i. Monthly, six monthly, and hence annual, average concentrations are always expected to be well below the 100 mg/l SO4 threshold.

ii. Only one monthly maximum in about 10 years is expected to slightly exceed 200 mg/l SO, and this occurrence is considered too rare to warrant concern.

. . . 111. Sulphate concentrations are rarely expected to persist above 100 mg/l.

iv. There is enough evidence, based on the fact that sulphate concentrations are projected to exceed 50 mg/l fairly frequently (and iii, above), to recommend that ’ aquatic moss populations be regularly monitored (at least annually)

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Therefore, an effluent sulphate concentration not exceeding 750 mg/l combined with an effluent discharge volume of 12000 m3/day is considered acceptable, on the condition that average annual in-stream concentrations do not exceed 100 mg/l and no 4-day average concentration exceed 250 mg/l SO,. A protection measure would be to have an alert level of 2OOmg/l SO4 in the river (i.e. a river flow of 0.5m3/s) at which point measures would be initiated to either reduce the sulphate concentration or effluent volume.

It is important to point out that the main beneficial use of Lower Feale as a source of potable water and as a migration route for salmon and seatrout would not be compromised by these recommendations.

The emission standards should be subject to compliance monitoring with regard to both effluent and in-stream sulphate concentrations. Checking the health of downstream aquatic moss and amphipod populations, with inspection for excessive sulphur bacteria growths in the mixing zone should form part of ongoing monitoring requirements. This could be accommodated easily during the usual annual biological monitoring.

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8 References

Bowell, R.J. (SRK Consulting) Sulphate and salt minerals - the problem of treating mine wastes. Mining Environmental Management. May 2000

Bosnic, J., Buljan, J., and Daniels, RP. 2000. Pollutants in tannery effluents: Definitions and Environmental Impacts; Limits for Discharge of Effluents into Water Bodies and Sewers. United Nations Industrial Development Organisation. Report uslRAs/92/120

Cabot, D. 1999. Ireland A Natural History. Harper Collins, London.

Canadian Council of Ministers for the Environment (CCME) 1999. Canadian Environmental Quality Guidelines: A Protocol for the derivation of Water Quality Guidelines for the Protection of Aquatic Life. Report.

CFB. Central Fisheries Board, Ireland. 2001. Annual Report.

ECOTOX. 2003. Ecotoxicology database. Sodium sulfate LC50 and EC& report, May 6. USEPA/ORD/NHEER.L. Mid-Continent Ecology Division. (www.eua. gov/medecotx )

Environnement Quebec. 2003. Criteres de qualite de 1 ‘eau de surjke au Quebec.

EPA Ireland (Environmental Protection Agency) 2001. Parameters of Water Quality: Interpretation and Standards. Environmental Protection Agency, Wexford.

EPA Ireland (Environmental Protection Agency) 2002. Water Quality in Ireland I998-2000. Environmental Protection Agency, Wexford.

European Environmental Agency. 2003. Sustainable Targets and Reference (STAR) value database. ( www.eea.eu.int )

Handbook on the Implementation of EC Environmental Legislation. Overview :Water Protection. (www.euroua.eu.int/comm/environment/enlar~~andboo~water.~df)

Jarman, P.W. 2000. Noranda Mining and Exploration Inc. Authorised discharge permit PE 00263. Ministry of Environment Lands and Parks, British Columbia.

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Maitland, P.S. 1972. A Key to the Freshwater Fishes of the British Isles, with notes on their distribution and ecology. Freshwater Biological Association. ScientiJic Publication 27. *

Mandaville, S.M. (2002) Benthic Macroinvertebrates in Freshwaters - Taxa Tolerance Values, Methods and Protocols. Soil and Water Conservation Society of Metro Halifax. (,www,lakes.chebucto.org/H-l/tolerance.adf)

O’Sullivan, A.D., D .A Murray, and M.L. One. 200 1. Phytoremediation of alkaline mine effluent using treatment wetlands. Abstracts of the Working Group II, COST Action 837 Programme. Phytoremediation of trace elements in contaminated soils and waters, European Union Co-operation in the field of Science and Technical Research (COST) Madrid, Spain, April 4-7, pp. 34-35.

Scherman P-A. and Palmer C.G. 1998. The Salinity Tolerances of the Mayfly Z’ricorythus nr. tin&us, from the Sabie River (Kruger National Park, SA) Institute for Water Research, Rhodes University (progress report: 1994-1998). (www.Darks- sa.co.za/conservation/scientific service&s ualmermavflv.html )

Singleton, H.J. 2000. Ambient Water Quality Guidelines for Sulphate. BCMinistry of Environment, Lands and Parks, and Environment, Canada. Technical Appendix.

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APPENDIX 1 - Toxicity of Sulphates to Aquatic Organisms

A Introduction

B Sulphates in the Environment

C Toxicity to Aquatic Life

c.1 Aquatic Plants

c.2 Aquatic Invertebrates

c.3 Freshwater Fish

c.4 Field Studies

C.5 Summary of Sulphate Toxicity and Effects

C.6 General Requirements for Guideline Derivation

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A Introduction

The following is a detailed review of scientific literature and relevant reports pertaining to toxic effects of sulphates to freshwater aquatic organisms.

B Sulphates in the Environment

Sulphate (Sod21 is a naturally occurring anion in surface waters and is essential to normal biological function of all organisms.

Sulphate is not a parameter monitored routinely by the EPA for Water Quality reports, nor is monitoring of SO, required under EC Regulations implementing the Freshwater Fish Directive (78/659/EEC). Singleton (2000) cites a report by McKee and Wolf (1963) that of the good game fish waters in the United States, 5% had ~1 lmg/L sulphates, 50% had ~32 mg/L. sulphates, and 95% had <90 mg/L sulphates. This does not mean, however, that sulphate is the limiting factor for the quality of these fisheries.

Studies relating to the effects of sulphate salts are primarily concerned with the effects of acidic sulphate-rich mine waste effluent, and tannery effluents, where the toxicity of heavy

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metals and acid to aquatic life, far outweighs that of sulphate alone. (O’Sullivan, 2001, Bowell, 2000)

C Toxicity to Aquatic Life

In general, sulphates are not considered toxic unless at very high concentrations (Singleton, 2000), and because of this there is a paucity of clear guidelines particularly with regard to freshwater life protection.

BC Ministry for the Environment, Lands and Parks (Canada) produced a r&port dealing entirely with the effects of sulphate on aquatic life. This valuable report critically reviews * available sulphate toxicity data, includes reports of specially commissioned toxicity studies, and sets ambient water quality limits for sulphate specifically for the protection of aquatic life (Singleton, 2000). The current review of the toxicity information available draws heavily on that report. The toxicity data considered acceptable for the development of a water quality guideline for sulphate is based bn the following strategy:

l Assessment of aquatic toxicological information for sodium sulphate, magnesium sulphate and potassium sulphate, which are soluble in water, and for calcium sulphate which is relatively insoluble. These compounds commonly occur in natural waters and allow an assessment of toxicity without the masking effect of more toxic substances such as heavy metals (e.g., as in copper sulphate) or acid (i.e., as in sulphuric acid). Effects of the cations Na, Mg, K, and Ca cannot be excluded however. l Exclusion of effects on brackish water (i.e., salt tolerant) species. l Focus on those species with low effect levels, due to the fact that a water quality guideline must assess the critical value necessary for the protection of all, including the most vulnerable, aquatic organisms.

C. 1 Aquatic Plants

It is recognised that sulphate in excess of 0.5 mg/l is essential for algal growth (Singleton, 2000).

The blue green algae of the genus,Anabaena was reported to undergo early sporulation when reared in media at concentrations of 2 16 and 3 11 mg/l (as SO,) according to Kanta and Sarma (1980, in Singleton 2000).

Chronic toxicity data for Selenastrum capricornatum revealed sulphates have an effect only at high concentrations. An ICz5 and IC50 for growth inhibition of 2210 and 3359 mg/l, respectively, with NOEC and LOEC of 1060 and 3650 mg/l SO,.

Aquatic mosses appear to be the most sensitive of all freshwater organisms to sulphate pollution. A German study (Frahm, 1975, in Singleton, 2000) demonstrated that a concentration of lOOmg/L SO, was toxic to the aquatic moss Fontanalis antipyretica. Mortality was also reported mortality in the aquatic moss species Fissendens crussipes, Leptodictum riparium, and Leskea polycarpa at concentrations of 150 mg/l, >200 mg/l, and >200 mg/l as K2S04 respectively, after one week exposure. To challenge the reliability of the work by Frahm (1975), Beak International Inc., with Michigan Technological University (1998) investigated sulphate toxicity in the aquatic moss, Fontanalis neomexicana. They concluded that in sulphate concentrations of up to 500 mg/l, in hard water conditions (160 mg/l CaCO$, there was no harmful effect to this species. However, the sensitivity of the endpoint effect (chlorophyll a and b content) has been questioned. The sensitivity of aquatic moss is an important limiting factor in the development of guidelines for sulphate.

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Aquatic macrophytes appear quite tolerant of sulphates. Root and stem growth of Eurasian Water Milfoil, Myriophyllum spicatum L., were affected over 32 days exposure at high concentrations (EC50 root and stem growth, 27857011 mg/l as Sod) (Stanley, 1974, cited Singleton, 2000).

C.2 Aquatic Invertebrates

Singleton (2000) reports on a series of acute bioassays performed by The Pacific Environmental Science Centre (PESC), specifically for the review of sulphate toxicity. The invertebrate species Daphnia, Hyalella and Chironomids were studied in media with three different water hardnesses, 25, 100, and 250 mg/l (as CaCOs). The 4%hr LCso’s for Daphnia

sp. in the various water hardnesses were 537, 6281 and 7442 mg/L SO,, respectively. For the HyaZeZZa sp. 96-hr LC5O’s were 205, 3711, and 6787 mg/l SO,, respectively. Chironomids appear tolerant of sulphate, with respective 96&r LCso’s of 6667,5868, and 4173 mg/l SO, in the different media. HyaZeZZa, in soft water, appears very sensitive to sulphates, but this conflicts with reports of HyaZeZZa azteca in saline prairie lakes withstanding, very high sulphate levels, perhaps an indication of acclimation over time.

Daphnia typically do not thrive in soft water so were not tested in a series of 21-day bioassays for chronic toxicity. Sulphate concentrations in excess of 625 mg/l were required to observe any adverse effects on Dbphnia in medium or hard water conditions (unpublished PESC data, in Singleton 2000). In a series of 7&y spiked sulphate bioassays the cladoceran Ceriodaphnia was shown to be quite tolerant, with sulphate concentrations in excess of at least 1060 mg/l required to disrupt biological function (BC Research Inc., 1998, in Singleton, 2000).

Dowden and Bennett (1965, in Singleton, 2000, ECOTOX) exposed invertebrates to sodium sulphate. Amphipods (species not given) had l-to-4 day L&‘s of ranging from 1609 to 595 mg/l SO,, respectively. 1 -to-4 day LCso’s for Daphnia magna were ranging from 5668 to 426 mg/l SO,, respectively. These workers also tested eggs of Lymnaea for hatching success and found that these snails were very tolerant of high sulphate levels (>2400 mg/l). Watre hardness was not reported for these studies.

One record was located of toxicity of sulphates to a mayfly. In a South African study the Leptohyphid species Tricolythus y1~ tinctus was subjected to elevated salinity using the salts NaCl, Na$Od, KCl, CaSO+ and MgS04 to assess acute and chronic toxicity. A brief report indicates that the main stress to these mayflies from increasing salinity was osmotic; that sulphate had an exacerbating synergistic effect; and that calcium had an ameliorative effect, on mortalities. Implied is that overall salinity is as important as the concentration of any one ionic group (Scherman and Palmer, 1998). An LCso (mortality) value in response to sulphate (as Na2S0.+) for this mayfly species is reported as approximately 440mg/l (Goetsch, 1997, in ECOTOX). Mayflies of the Family Leptohyphidae are not represented in Ireland. They are part of the North American macro-invertebrate fauna, as stream dwelling collector-gatherers, where they have a slightly better than moderate tolerance for organic pollution (Mandaville, 2002). But it is not possible to infer toxicity for Irish mayfly fauna based on this study.

C.3 Freshwater Fish

In the literature, one freshwater fish is reported as being vulnerable to sulphates. A North American species, striped bass (Morone saxitilis) studied by Hughes (1973, in ECOTOX report) showed l-to-4 day L&O’s ranging from 2000-250 mg/l SO4 , respectively (Hughes, 1973, in Singleton, 2000).

Trout and salmon appear to be quite tolerant to sulphates. Singleton (2000) reviewed PESC acute toxicity bioassays performed on rainbow trout (Oncorhynchus mykiss) and coho salmon

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(Oncorhynchus kisutch) exposed to SO4 under the hard water conditions of 25, 100, and 250 mg/l (as CaC03). For rainbow trout 96-hr LCsO’s were 5000, 9750, and 9900 mg/l Sod, respectively. For coho salmon the 96&r LCso’s were 5742, 9550, and 9875 mg/l SO,, respectively.

Chronic toxicity tests revealed that for rainbow trout embryo viability to be significantly disrupted concentrations of sulphates in excess of 1280 mg/l were necessary (Unpublished BC MELP data, 1996, in Singleton, 2000)

For fathead minnow (Pimephales promelas) shows a high tolerance to sulphates, with an LCso of 1355 mg/l SO4 reported, and an I& and ICso for growth of 2255 and 3450 nag/L SO,. (BC Research, 1998, in Singleton, 2000). Minnows in Ireland are of the species Phoxinusphoxinus (Maitland, 1972), but whether or not data for the fathead minnow can serve as an indicator for this resident Irish species is unknown.

Boge et al (1982) examined the effects of sulphate ions on enzymatic activities in the gut of the European eel (Anguilla angzdla) under constant temperature conditions and when exposed to heat shock. Enzyme activity was altered under both regimes when exposed to 176 mg/l SO, (as Kz SO, and CaS04). These changes may be adaptive responses and may not be significantly detrimental in the long term.

The euryhaline species (sea trout, Atlantic salmon and European eel) can be expected to tolerate fluctuations in sulphate concentration as seawater typically has a high sulphate concentration (2700mg/l) relevant to natural freshwaters, and these fish are physiologically adapted to life in both environments.

C.4 Field Studies

Singleton (2000) reports anecdotal evidence that an average of 71 mg/l SO, with a range of 27.7 to 189 mg/l, can stimulate excessive growth of sulphur bacteria which can smother creek beds and alter the macro-invertebrate community. This has not been tested, but has been observed in parts of Canada in the presence of sulphate-enriched effluents.

Other field studies have been undertaken in streams impacted by sulphate-rich, acid-mine waste, where the toxicity of other substances (e.g., metals, acid) have masked the effects of sulphates alone.

C.5 Summary of Sulphate Toxicity and Effects

Generally, for most aquatic organisms tested including fish, toxicity of sulphate increases with decreasing water hardness. Ca2+ has been shown to ameliorate sulphate toxicity dramatically in an amphipod (Hyalella) and a cladoceran (Daphnia), where a four-fold increase in water hardness (from 25-100 mg/l CaCO$ resulted in an average 15-fold increase in sulphate concentration required to produce 50% mortality of organisms.

The lowest effect level that was reported in the literature was 205 mg/l in soft water (25 mg/l CaC03) to the freshwater amphipod, HyaZeUa. Amphipods of the genus Gammarus are present in the River Feale in low abundance both upstream and downstream of the present discharge. It is unknown whether they would, display a similar sensitivity (as HyaZeZZa) to sulphates, but generally, the literature points to the possibility that amphipods may be quite sensitive to sulphates, particularly in soft waters.

The lowest (most toxic) concentration of sulphate reported in literature reviewed for fish is the 4-day LC50 for a North American species, Morone saxitilis (striped bass) of 250 mg/l Sod.

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The lowest LC!,, (no mortality) for this species was 100 mg/l SO,, after 4 days exposure. There are no purely freshwater bass species in Ireland, but according to Singleton (2000) these data may serve as an indicator for perch species, of which Percafluviatilis is resident in Ireland.

Biochemical changes (possibly an adaptive response) have been reported in the European eel at sulphate concentrations as low as 176 mg/l, but long-term effects of the exposure are not reported.

C.6 General Requirements for Guideline Derivation

In general, the minimum data set for the derivation of interim freshwater life guidelines requires the following (from CCME, 1999):

MSH: at least two acute and/or chronic studies on two or more fish species (one of which includes a resident species). INVERTEBRATES: at least two acute and/or chronic studies on two or more invertebrate species from different classes (one of which includes a resident planktonic species such as Daphnia) PLAiVTS: if a plant species is the most sensitive species in the data set, then this study can be used for guideline derivation.

In this case the data set requirements are not fully met for derivation of an interim guideline for the River Feale, primarily as there are no specific toxicity data for a resident fish species. The guideline must be established based on indications from other species in the literature, and best principles, as follows:

FISH: Striped bass- the larvae of which are sensitive to sulphates - may serve as an indicator for Perca fluviatilis. Coho salmon and rainbow trout, both of which are very tolerant of high sulphate levels, may serve as indicators for Atlantic salmon and brown trout. Effects on the European eel are discounted as these are biochemical and not necessarily toxic. IWERTEBRATES: The amphipod Hyalella may serve as an indicator for amphipods species resident in the Feale (e.g., Gammarus sp.). Data for Daphnia and Lymnaea and Chironomids are appropriate. PLANTS: Data for the aquatic moss Fontanalis is appropriate.

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APPENDIX 2: International Guidelines and Discharpe Limits for Suluhates

1. 2.

International Guidelines for sulphates International limits for sulphate discharging to surface waters Table 1:Intemational Pollution Limits for efluent emissions to su$ace waters

1. International guidelines for sulphates

Most water quality objectives for sulphates relate to maximum allowable concentrations in surface waters intended for abstraction for public water supply, and concentrations in finished drinking water.

Ireland’s environmental quality standard (EQS), or mandatory value, for sulphate is 200 mg/l in Al, A2 and A3 waters (intended for abstraction for drinking water supply) under regulations implementing the Surface Water Directive (75/44O/EEC). The mandatory value for finished drinking water is 250 mg/l sulphate, under regulations implementing the Drinking Water Directive, 98/83/EC (EPA Ireland, 2001). There are no specific guidelines for the protection of aquatic life.

Very few jurisdictions, in fact, have recommendations for sulphate concentration specifically for the protection of aquatic ecosystems.

Environment Quebec, have a provision for sulphate for the protection of aquatic life, recommending 300 mg/L SOJ, as a maximum concentration to prevent acutely toxic effects, but no justification for this guideline is given.

To protect freshwater organisms in British Columbia, a water quality guideline of 100 mg/L for dissolved sulphate, measured as SO4, is recommended. This guideline is a maximum concentration that should not be exceeded at any time. The apparent sensitivity of aquatic mosses to sulphates has motivated a further recommendation that for impacted waterbodies with concentrations exceeding 50 mg/L Sod, the health of aquatic moss populations should be checked on an occasional basis (Singleton, 2000).

2. International limits for sulphates discharging to surface waters

Guidelines relating to maximum allowable concentrations of sulphate at the point of discharge are primarily concerned with the effects of the effluent in sewers because sulphate is corrosive to concrete. These limits are not relevant to the current review as they have not been devised for protection of aquatic life.

Bosnic et al. (2000) reviewed international limits for discharge of effluents into water bodies 1 and shows that limits for sulphates discharging to surface waters range ti-om 150 mglL in the

Netherlands to 2000 mg/L in Spain (Table 1).

In Ireland the discharge of sulphate at elevated levels occurs at Outukompu Zinc-Tara Mines, Navan. Research in to the success of passive wetland treatment for sulphate (and heavy metal) pollutants show that sulphate-rich effluent enters treatment beds at concentrations of up to 1700 mg/L where reduction by species of Sulphate Reducing Bacteria (SRB) removes approximately 78% of sulphates. This would result in residual sulphates being discharged to the receiving watercourse at a concentration of approximately 370 mg/L. (O’Sullivan, 2000).

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No specific guideline for maximum sulphate concentration in discharges could be found for Irish waters.

A decision by BC Ministry of Environment, Lands and Parks, Canada, authorises a mining company to discharge effluent to a creek with a sulphate concentration of no greater than 500mg/l. This is subject to achieving an annual average of less than or equal to 1OOmg /I SO,, and less than or equal to 250 mg /l SO, in any single sample taken downstream of the discharge point (Jarman, 2000).

Table 1: International Limits for Effluent Discharge to Surface Waters

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