Regulating Contaminated Sediments in Aquatic Environments: A Hydrologic Perspective W. ANDREW MARCUS Department of Geography Room 1113 Lefrak Hall University of Maryland College Park, Maryland 20742, USA ABSTRACT/A number of state and federal agencies are presently f~ttempting to develop menagernent strategies for contaminated aquatic sediments. Until now, research and debate on sediment guidelines and regulations has focused almost exclusively on biological and chemical techniques for determining when sediments pose an environmental risk. Hy- drologic factors must also be considered, however, if these biochemically based techniques for establishing sediment quality standards are to be feasible. Hydrologic issues that need to be addressed include how to define the boundaries of the aquatic environment, the scope of sediment regula- tions in ephemeral waters, regulations and sampling proce- dures in heterogeneous sediments, and timing of samples for monitoring and enforcement purposes Contamination of aquatic sediments can pose a se- vere and long-lasting threat to the environment. Damages occur when harmful materials migrate into the pore water and water column or are bioaccumu- lated by benthic flora and fauna and transmitted up the food chain. Only recently, however, has recogni- tion of the severity and widespread occurrence of these environmental effects forced public agencies to consider developing management strategies for regu- lating contamination in sediments. The state of Wash- ington, the US Army Corps of Engineers, and the US Environmental Protection Agency, for example, are attempting to develop sediment contamination guide- lines for Puget Sound (PTI Environmental Services 1988), while the Chesapeake Bay Program's toxics re- duction strategy calls for development of a sedimem quality evaluation protocol by December 1991 (Water Quality Task Group 1988). In order to manage aquatic sediments, agencies must first determine what constitutes polluted and clean sediments. Unfortunately, defining acceptable pollution levels in sediments is a complex task, because a given quantity of sediment contamination may or may not pose a threat depending on the chemical form of the contaminant and the biogeochemistry of the aqueous environment, which typically vary on a sporadic and seasonal basis. The large majority of re- search on developing management strategies has thus been biochemical in nature and has focused on estab- lishing when sediments pose an environmental threat (for example, Chapman 1986, Francingues and others 1984, PTI Environmental Services 1988, Pavlou 1987), with little attention paid to potential problems of im- KEY WORDS: Contamination; Pollution; Sediments;Hydrology;, Regu- lation plementing these techniques in the variable hydrologic conditions encountered in the natural aquatic environ- ment. The nature of the hydrologic environment, however, can play a major role in determining whether sediment criteria are reasonable and enforce- able. This article examines some of the important hy- drologic factors that must be considered before any large-scale toxins strategy for aquatic sediments can be implemented and enforced. Specifically, the article outlines: (1) hydrologic factors affecting use of sedi- ment quality standards; (2) the implications of these hydrologic factors in choosing the best possible tech- niques for establishing sediment quality standards; and (3) some suggestions for coping with problems posed by hydrologic constraints when establishing sed- iment quality criteria. Approaches for Determining Permissible Contamination Levels In order to appreciate the potential hydrologic problems inherent in managing contaminated aquatic sediments, one must have a general understanding of the possible approaches for assessing sediment pollu- tion. The following discussion briefly summarizes the maor categories of techniques used for determining when sediments are contaminated and mentions some of the commonly cited biochemical and regulatory ad- vantages and disadvantages of each technique. More comprehensive summaries of these techniques and the biochemical problems associated with establishing sedi- ment guidelines are contained in Chapman (1989), Dickson and others (1987), Engler (1980), and JRB Associates (1984). To date, the large majority of cited advantages and disadvantages with each technique have been based on biological, chemical, or legal cri- teria, with little examination of hydrologic factors. Environmental Management Vol 13, No 6, pp 703-713 9 1989Sprirlger-Vedag NewYorkInc