ASTM E1706-20

1.1 Relevance of Sediment Contamination-Sediment provides habitat for many aquatic organisms and is a major repository for many of the more persistent chemicals that are introduced into surface waters. In the aquatic environment, both organic and inorganic chemicals may accumulate in sediment, which can in turn serve as a source of exposure for organisms living on or in sediment. Contaminated sediments may be directly toxic to aquatic life or can be a source of contaminants for bioaccumulation in the food chain.

1.2 Sediment Assessment Tools-Several types of information may be useful in assessing the risk, or potential risk, posed by sediment contaminants, including: (1) chemical analysis of sediment contaminants; (2) sediment toxicity tests, (3) bioaccumulation tests; and (4) surveys of benthic community structure. Each of these provides a different type of information to the assessment, and integrating information from all four lines of evidence may often provide the most robust assessments.

1.3 Strengths of Toxicity Testing of Contaminated Sediments-Directly assessing the toxicity of contaminated sediments provides some of the same advantages to sediment assessment that whole effluent toxicity testing provides to management of industrial and municipal effluents. As for effluent tests, direct testing of sediment toxicity allows the assessment of biological effects even if: (1) the identities of toxic chemicals present are not (or not completely) known; (2) the influence of site-specific characteristics of sediments on toxicity (bioavailability) is not understood; and (3) the interactive or aggregate effects of mixtures of chemicals present are not known or cannot be adequately predicted. In addition, testing the response of benthic or epibenthic organisms exposed via sediment provides an assessment that is based on the same routes of exposure that would exist in nature, rather than only through water column exposure.

1.4 Relating Sediment Exposure to Toxicity-One of the challenges with sediment assessment is that the toxicity of sediment contaminants can vary greatly with differences in sediment characteristics; a bulk sediment concentration (normalized to dry weight) may be sufficient to cause toxicity in one sediment, while the same concentration in another sediment does not cause toxicity (for example, Adams et al. 1985) (1).2 Factors such as the amount and characteristics of the organic carbon present in sediment can alter the bioavailability of many chemicals (Di Toro et al. 1991 (2); Ghosh 2007 (3)), as can other characteristics such as acid volatile sulfide or iron and manganese oxides (Di Toro et al. 1990 (4), Tessier et al. 1996 (5)). Direct measurement of toxicity in contaminated sediments can provide a means to measure the aggregate effects of such factors on the bioavailability of sediment toxicants.

1.5 Understanding the Causes of Sediment Toxicity-While direct testing of sediment toxicity has the advantage of being able to detect the effects of any toxic chemical present, it has the disadvantage of not providing any specific indication of what chemical or chemicals are causing the observed responses. Other techni

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Published:

04/01/2020

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Document History

ASTM E1706-20

ASTM E1706-05(2010)

ASTM E1706-05e1

ASTM E1706-05

ASTM E1706-00

ASTM E1706-00e2

ASTM E1706-00e1