6. Assessing Biological Effects

Many hazardous substances associate readily with sediments in marine, estuarine and freshwater environments. The science of sediment quality evaluation associated with characterizing the ecological effects of these substances has progressed dramatically over the past 30 years. It is now apparent that to reach conclusions that are accurate (related to actual field conditions), assessments of sediment quality involve much more than simply assessing sediment toxicity using laboratory tests on field-collected sediments. Optimal assessments of quality, hazard or risk associated with sediments integrate multiple methods and approaches. For example, many authors now advocate that laboratory toxicity testing be performed concurrently with physicochemical characterizations, indigenous biotic community assessment and in situ-based approaches to characterize exposures from overlying waters, sediments and advective groundwater-pulse events (Burton, 1991; Burton et al., 2005a; Greenberg et al., 2002; Adams et al., 2005). Sediment quality assessment tools and approaches also include toxicity identification evaluations (TIEs) (USEPA, 2007; Ho and Burgess, 2009), assessment of abiotic factors as stressors (Burton and Johnston, 2010) and toxicological evaluation of tissue residue (Meador et al., 2008; Sappington et al., 2011). However, compartmentalization rather than integration of key approaches and issues is a potential pitfall for sediment quality evaluation. If only one or two assessment methods are used, or any are used incorrectly, the resulting conclusions may be erroneous or have a high degree of uncertainty.