ASTM E2591-22 PDF

SIGNIFICANCE AND USE 5.1 While federal criteria and state standards exist that define acute and chronic “safe” levels in the water column, effects levels in the sediment are poorly defined and may be dependent upon numerous modifying factors. Even where USEPA recommended Water Quality Criteria (WQC, (49)) are not exceeded by water-borne concentrations, organisms that live in or near the sediment may still be adversely affected (50). Therefore, simply measuring the concentration of a chemical in the sediment or in the water is often insufficient to evaluate its actual environmental toxicity. Concentrations of contaminants in sediment may be much higher than concentrations in overlying water; this is especially true of hydrophobic organic compounds as well as inorganic ions that have a strong affinity for organic ligands and negatively-charged surfaces. Higher chemical concentrations in sediment do not, however, always translate to greater toxicity or bioaccumulation (51), although research also suggests that amending sediment with organic matter actually increases the bioaccumulation of contaminant particles (52, 53). Other factors that can potentially influence sediment bioaccumulation and toxicity include pH mineralogical composition, acid-volatile sulfide (AVS) grain size, and temperature (54-56). Laboratory toxicity tests provide a direct and effective way to evaluate the impacts of sediment contamination on environmental receptors while providing empirical consideration of all of the physical, chemical and biological parameters that may influence toxicity. 5.2 Amphibians are often a major ecosystem component of wetlands around the world, however limited data are available regarding the effects of sediment-bound contaminants to amphibians (39, 41, 43, 55, 57, 58). Laboratory studies such as the procedure described in this standard are one means of directly assessing sediment toxicity to amphibians in order to evaluate potential ecological risks in wetlands. 5.3 Results from sed... SCOPE 1.1 This standard covers procedures for obtaining laboratory data concerning the toxicity of test material (for example, sediment or hydric soil (that is, a soil that is saturated, flooded, or ponded long enough during the growing season to develop anaerobic (oxygen-lacking) conditions that favor the growth and regeneration of hydrophytic vegetation)) to amphibians. This test procedure uses larvae of the northern leopard frog (Lithobates pipiens). Other anuran species (for example, the green frog (Lithobates clamitans), the wood frog (Lithobates sylvatica), the American toad (Bufo americanus)) may be used if sufficient data on handling, feeding, and sensitivity are available. Test material may be sediments or hydric soil collected from the field or spiked with compounds in the laboratory. 1.2 The test procedure describes a 10-d whole sediment toxicity test with an assessment of mortality and selected sublethal endpoints (that is, body width, body length). The toxicity tests are conducted in 300 to 500-mL chambers containing 100 mL of sediment and 175 mL of overlying water. Overlying water is renewed daily and larval amphibians are fed during the toxicity test once they reach Gosner stage 25 (operculum closure over gills). The test procedure is designed to assess freshwater sediments, however, R. pipiens can tolerate mildly saline water (not exceeding about 2500 mg Cl-/L, equivalent to a salinity of about 4.1 when Na+ is the cation) in 10-d tests, although such tests should always include a concurrent freshwater control. Alternative test durations and sublethal endpoints may be considered based on site-specific needs. Statistical evaluations are conducted to determine whether test materials are significantly more toxic than the laboratory control sediment or a field-collected reference sample(s). 1.3 Where appropriate, this standard has been designed to be consistent with previously developed methods for assessing s...