Site‐specific marine water‐quality criterion for cyanide

Brix, Kevin V.; Cardwell, Rick D.; Henderson, Douglas G.; Marsden, A.

doi:10.1002/etc.5620190923

Cited by 3 publications

(1 citation statement)

References 4 publications

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“…Although the acute criterion increased slightly, the CCC decreased slightly because the final ACR increased from 8.568 to 9.659, which resulted from calculating chronic values from EC20 values rather than the geometric mean of the NOEC and LOEC, as was done in the 1984 AWQC (Table 2). Lowered to protect rainbow trout GMAV = Genus mean acute value FAV = Final acute value CMC = Criterion maximum concentration ACR = Acute-chronic ratio Note: all concentrations are in μg/L free cyanide expressed as CN For saltwater organisms, additional cyanide toxicity testing with several Cancer species (Brix, et al 2000, Northwestern Aquatic Sciences 2005a, 2005b, 2005c and the copepod Acartia tonsa (Parametrix 2006a(Parametrix , 2006b) resulted in substantial changes to the proposed CMC, but a smaller change to the recommended chronic criterion due to a difference in the recommended final saltwater organism ACR. The proposed acute saltwater criterion is approximately 20 times greater than the current acute criterion (Table 3).…”

Section: Resultsmentioning

confidence: 99%

Reassessment of Cyanide Ambient Water Quality Criteria: An Integrated Approach to Protection of the Aquatic Environment

Gensemer¹,

DeForest²,

Cardwell³

et al. 2006

proc water environ fed

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The U.S. Environmental Protection Agency's (USEPA) current ambient water quality criteria (AWQC) for cyanide were developed in 1984. Since this time, additional research on cyanide toxicity and analytical chemistry has suggested that cyanide AWQC values need to be updated to reflect the current state-of-the-science and to ensure that the methods for implementing the cyanide AWQC reflect the bioavailable and toxic forms of cyanide. Therefore, the Water Environment Research Foundation (WERF) sponsored a reassessment of the AWQC for cyanide by initiating a thorough review of the current scientific literature on cyanide and conducting additional laboratory studies to further understand cyanide chemistry and toxicity. Consistent with the USEPA's draft strategy for developing AWQC, this evaluation also considered whether the cyanide AWQC are protective of benthos, threatened and endangered (T&E) species, and aquatic-dependent wildlife. This reassessment of AWQC for cyanide resulted in proposed freshwater acute and chronic criteria of 23 and 4.8 µg CN/L, respectively, which are comparable to the current freshwater acute and chronic criteria of 22 and 5.2 µg CN/L (free cyanide). For saltwater organisms, the reassessment resulted in proposed acute and chronic criteria of 20 and 4.1 µg CN/L (free cyanide), respectively, compared to the current saltwater acute and chronic criteria which are both 1.0 µg CN/L. The difference in the current and proposed saltwater criteria values is attributed to recent cyanide toxicity testing with several crab species in the genus Cancer and the copepod Acartia tonsa, which suggests this genus is not as sensitive to cyanide as previous cyanide toxicity testing indicated. A sediment-based cyanide criterion does not appear warranted if it is assumed that benthic organisms are not inordinately more sensitive to cyanide than the water column organisms that drive the basis for the proposed freshwater and saltwater criteria (the available cyanide toxicity data do not suggest that they would be), and given that bioavailable forms of cyanide are not expected to accumulate appreciably in sediment. Cyanide should thus be effectively regulated based on water column-based criteria and concentrations. Based on a combination of available empirical and estimated cyanide toxicity values for T&E species, the proposed freshwater criteria appear to be protective 5709 WEFTEC®.06

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Section: Resultsmentioning

confidence: 99%

Reassessment of Cyanide Ambient Water Quality Criteria: An Integrated Approach to Protection of the Aquatic Environment

Gensemer¹,

DeForest²,

Cardwell³

et al. 2006

proc water environ fed

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Bioavailability of cyanide and metal–cyanide mixtures to aquatic life

Redman¹,

Santore²

2012

Enviro Toxic and Chemistry

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Cyanide can be toxic to aquatic organisms, and the U.S. Environmental Protection Agency has developed ambient water-quality criteria to protect aquatic life. Recent work suggests that considering free, rather than total, cyanide provides a more accurate measure of the biological effects of cyanides and provides a basis for water-quality criteria. Aquatic organisms are sensitive to free cyanide, although certain metals can form stable complexes and reduce the amount of free cyanide. As a result, total cyanide is less toxic when complexing metals are present. Cyanide is often present in complex effluents, which requires understanding how other components within these complex effluents can affect cyanide speciation and bioavailability. The authors have developed a model to predict the aqueous speciation of cyanide and have shown that this model can predict the toxicity of metal-cyanide complexes in terms of free cyanide in solutions with varying water chemistry. Toxicity endpoints based on total cyanide ranged over several orders of magnitude for various metal-cyanide mixtures. However, predicted free cyanide concentrations among these same tests described the observed toxicity data to within a factor of 2. Aquatic toxicity can be well-described using free cyanide, and under certain conditions the toxicity was jointly described by free cyanide and elevated levels of bioavailable metals.

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