Abstract

  This paper is a synthesis of the 44 presentations at the First International Symposium on Sediment Quality Assessment (Sweden, August 1994). The paper includes Initial Premises, Sediments, Tools (with particular emphasis on bioassays), Strategies and Challenges. Major testable hypotheses are proposed as follows (ranging in complexity, recognizing differences apparent at the Symposium in level of expertise and knowledge): (1) there is no single 'perfect' method of sediment assessment, there are only 'tools in the toolbox'; (2) significant sediment pollution (contamination resulting in adverse biological effects) comes from non-anthropogenic sources; (3) artificial sediments will provide future reference comparisons; (4) knowledge of suspended sediments is required to understand bedded sediments; (5) ammonia and/or hydrogen sulfide cannot explain all sediment toxicity, in particular non-acute responses; (6) subcellular (e.g., genetic) responses are a research tool, not yet appropriate for monitoring or assessment; (7) although the effects of sediment storage cannot be predicted, non-toxic and highly toxic sediments are less affected by prolonged storage than are moderately toxic sediments; (8) sediment ingestion is a more important route of exposure than pore water for some organisms; (9) water column organisms and aqueous exposures should not be used for whole-organism sediment tests; (10) validation of sediment bioassays is not always simple or possible. Two major conclusions are: (i) generalizations are not [yet] possible regarding sediment quality; (ii) correctly assessing sediment quality is primarily a function of the correct reference comparison.

Keywords: sediment, aquatic, toxicity, assessment