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A Comparison of Temporal Trends in Ambient and Compliance Trace Element and PCB Data in Pool 2 of the Mississippi River, 1985-1995

By Anderson, J.A.

The ambient and compliance water-quality monitoring community needs to work together in order to make better management decisions. Integration of ambient and compliance water-quality data will optimally lead towards improved decision making. The Intergovernmental Task Force on Monitoring (ITFM) has several goals, one of which is integration of ambient and compliance water-quality data collection efforts. The degree of integration that can be accomplished will be influenced by similarity in trends between the datasets. This thesis advances that ITFM goal; it was a pilot project to determine the similarity in temporal trends between ambient and compliance priority pollutant water-quality data collected from an urbanized pool of the Mississippi River. Retrospective ambient water, bed sediment, fish tissue, and compliance (wastewater) trace element and PCB data collected in Pool 2 of the Mississippi River from 1985-1995 were statistically analyzed. Results from the non-parametric Mann-Kendall trend test indicated that only 25% of trends were statistically significant (p<.05). Possible reasons for this were low sample sizes, a high percentage of samples 'below the detection limit', or simply few trends were present. A combination of these factors and logistical differences among ambient monitoring programs made it difficult to assess temporal trends in ambient media. Trends in compliance data were more distinct, most pollutants had statistically significant decreases; no statistically significant increases were detected. For 7 of the 11 priority pollutants studied, statistically significant decreas ing trends were found in portions of both the ambient and compliance datasets.

In order to improve data-sharing, it is recommended that the ambient monitoring community improve communication, standardize methodologies and integrate compliance data into their monitoring efforts. Specific examples that can improve integration include creating a data analysis protocol, and requiring compliance facilities to take ambient samples in return for a reduction in compliance sampling. Data-sharing and cooperation among those monitoring water-quality should be a logical step in the future because of the increasing pressures on resources for environmental monitoring.