The ETV ProgramÃ¢â‚¬â„¢s AMS Center conducts third-party performance testing of commercially available technologies that detect or monitor natural species or contaminants in air, water, soil, and sediment. The purpose of ETV is to provide objective and quality assured performance data on environmental technologies so that users, developers, regulators, and consultants can make informed decisions about purchasing and applying these technologies. Stakeholder committees of buyers and users of such technologies recommend technology categories, and technologies within those categories become priorities for testing. Among the technology categories recommended for testing are toxicity testing technologies, including sediment and aqueous toxicity for assessment of environmental quality in marine, freshwater and Earnestine systems. Traditionally, the bio-availability and toxicity of contaminated sediments or water samples are assessed on grab or composite samples collected in the field and tested in a laboratory. In the laboratory, test organisms are added to site sediment or water samples in beakers and exposed under controlled conditions (e.g., temperature, pH, salinity, photoperiod, feeding regime, aeration) for a specified time period (e.g., EPA, 1994a; EPA, 2000; ASTM, 2000; ASTM, 2010). This laboratory-based method of assessing sediment quality, although widely used and well established, does not necessarily represent the true in-situ exposure and effects to organisms in the field. This is especially true when the source of contamination is ephemeral, meaning exposure varies over time and with ambient conditions. Another challenge with laboratory testing is that sediment sample manipulation removes the natural vertical contaminant stratification, which in turn alters the exposure to test organisms. Such manipulation may also result in alteration of the contaminant bio-availability through processes including degradation, volatilization, and redox changes. Sediment samples removed from the field undergo physical and chemical changes which change the bio-availability and toxicity of the contaminants and may lead to misleading results in the laboratory and subsequent difficulty in program decision making. In addition, laboratory tests may overestimate toxicity from sediment-associated contaminants due to buildup of contaminant concentrations in the overlying water as toxicants adsorb from the sediment into the WC. In aqueous exposures, laboratory tests may also misrepresent actual exposure in the field when static exposures are used as a means of assessing the potential for adverse effects of a time-varying.