Sediment chemistry provides information on contamination, however it does not provide information of biological effects (Chapman, 1990). Sediment chemistry is used as a screening tool to determine the contaminants that are most likely to be destructive to organisms present in the benthic community at a specific site. During analysis, sediment chemistry data does not depend strictly on comparisons to sediment quality guidelines when utilizing the triad approach. Rather, sediment chemistry data, once collected for the specific site, is compared to the most relevant guide values, based on site characteristics, to assess which chemicals are of the greatest concern. This technique is used because no one set of data is adequate for all situations. This allows you to identify the chemicals of concern, which most frequently exceed effects-based guidelines. Once the chemical composition of the sediment is determined and the most concerning contaminants have been identified, toxicity tests are conducted to link environmental concentrations to potential adverse effects.