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HISTORICAL RECONSTRUCTION OF POLLUTION STRESS AND RECOVERY IN AN URBAN ESTUARY
Citation:
Latimer, J S., W S. Boothman, S Jayaraman, R A. McKinney, AND D J. Cobb. HISTORICAL RECONSTRUCTION OF POLLUTION STRESS AND RECOVERY IN AN URBAN ESTUARY. ACS Environmental Chemistry Division Syposia, Environmental Chemistry: Emphasis On EPA And EPA Supported Research, Washington DC, August 20-25, 2000.
Description:
The major problems in the coastal areas result from human overutilization of the environment. Pollution is correlated with population density and there is currently a major effort to monitor estuaries to assess their ecological status. These monitoring efforts are important because the data collected permit scientists and managers to relate drivers), stressors, and effects. After associations are elucidated, mechanistic models can be constructed to develop hypotheses that are tested to verify system responses to drivers and stressors. Once relationships between drivers, stressors, and effects are established, managers have a sound scientific basis to build consensus on solutions to problems.
The goal of the Clean Water Act is to restore and maintain the chemical, physical, and biological integrity of the Nation's waters (33 U.S.C. s/s 1251 et seq. (1977)). The term "integrity," while ambiguous, implies a knowledge of the characteristics of unimpaired water bodies (i.e., reference conditions) and their watersheds. Understanding ecological conditions pre-dating significant anthropogenic impact is important because any effort to improve the status of degraded systems, or maintain undegraded systems, comes at a price. How clean is clean? The answer to this question is a value judgment by society; however, a reasonable judgement requires an understanding of the characteristics of a "clean" ecosystem. For these reasons the regulatory community needs to be able to define reference conditions (EP A, Draft (March 1999)). One method of defining reference conditions is to identify areas that have been minimally impacted by human activities and assess their structural and functional characteristics. This comprises the "best attainable" condition (EPA, Draft (March 1999)). This approach is problematic for several reasons. First, it is a difficult task to match estuarine systems in all but a few variables. Second, there are no systems in the contiguous U.S. that are sufficiently pristine to qualify as a reference site. In addition, when reference sites are subject to political boundaries, i.e., within states, an arbitrary definition of reference conditions is likely.
Another way to define reference conditions is to determine system structural and functional characteristics before significant human impact. This is the historical reconstruction approach which is being used in lake and reservoir bioassessments (EPA, 1998). It has two main components: (1) anthropological and (2) paleoecological. The main assumption in this
approach is that past records of human activities and observations (museum records, references, and anecdotal information), coupled with biogeochemical analysis of sediment cores, provide a representation of conditions before human activities significantly altered the environment (Pearce, J., 1999). Once reference conditions are characterized, departures from them can be measured, thus allowing degradation and recovery to be gauged against "natural" conditions. This has several advantages over the "best attainable" approach: (I) each system is self-referenced, (2) relationships between natural stressors and effects can be determined, and (3) information on trends can be obtained.