M6 AM Suspended and Bedded Sediments and Nutrients: Exposure-response Relationships
Monday, 14 November 2005: 8:00 AM - 11:40 AM in 324-326

(DET-1117-743852) Using exposure-response relationships for nutrient criteria development for flowing waters of the Upper Midwest.

Detenbeck, N.¹, Bauer, C.², Thompson, J.¹, Yue, S.^{3, 4}, Pfeifer, D.², ¹ U.S. Environmental Protection Agency, Office of Research and Development, Duluth, MN, US² U.S. Environmental Protection Agency, Region 5, Chicago, IL, US³ formerly NRC Senior Research Associate with U.S. Environmental Protection Agency's Office of Research and Development, Duluth, MN, US⁴ now Hazen and Sawyer, New York, NY, US

ABSTRACT- State water quality inventories have repeatedly cited nutrients as a major cause of ambient water quality use impairments. As a result, the United States Environmental Protection Agency (USEPA) published recommended water quality criteria for nutrients in 2001 to serve as a starting point for states and others to develop more refined nutrient criteria, including criteria based upon exposure-response relationships between nutrients and waterbody uses. States and others are utilizing ongoing research, particularly in flowing waters, to determine quantitative exposure-response relationships among nutrients and parameters that are more directly related to waterbody uses. Refining these exposure-response relationships to support criteria development requires the partitioning of variation in these relationships among stream types because (1) algal accrual rate can be limited by shading, herbivory, and the instream flow regime and (2) algal accrual effects on instream dissolved oxygen can be influenced by primary production and instream respiration. To better understand the effects of nutrients on Upper Midwest streams, all subwatersheds at the HUC12 scale have been characterized for climatic, soils, geomorphology, and land-use/land-cover variables expected to control flow regime, and subjected to a nonparametric cluster analysis to identify unique hydrologic classes. A regional database also has been constructed comprising historical monitoring data for stream hydrology, water quality, habitat, algal biomass, and algal, macro-invertebrate, and fish community composition. Exposure-response relationships between nutrients and minimum dissolved oxygen levels, BOD, periphyton or plankton biomass, and between nutrients and aquatic community metrics are being examined for differences in sensitivity across the identified watershed classes. This abstract does not necessarily reflect EPA policy.

Key words: nutrients, exposure-response relationships, nutrient criteria, aquatic life