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United States Department of Agriculture

Agricultural Research Service

Title: EFFECTS OF SUSPENDED SEDIMENTS ON THE CHLOROPHYLL-PHOSPHORUS RELATIONSHIP IN OXBOW LAKES

Authors
item Knight, Scott
item Cullum, Robert
item Cooper, Charles
item Lizotte, Richard

Submitted to: International Journal of Ecology and Environmental Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 28, 2008
Publication Date: August 21, 2008
Citation: Knight, S.S., Cullum, R.F., Cooper, C.M., Lizotte Jr, R.E. 2008. Effects of Suspended Sediments on the Chlorophyll-phosphorus Relationship in Oxbow Lakes. International Journal of Ecology and Environmental Sciences 34(1): 01-06.

Interpretive Summary: Agricultural activities have been implicated as the sources of such pollutants as sediments, pesticides and nutrients. The Clean Water Act requires states to improve impaired waters by establishing Total Maximum Daily Loads (TMDLs) of these pollutants that will be allowed in our rivers, lakes and streams. Research conducted as a part of the Mississippi Delta Management Systems Evaluation Area project (MSEA), showed that the amounts of sediment and nutrients in oxbow lakes were related. Furthermore this research showed that reducing sediment using good conservation practices allowed the plankton in the lake water to more effectively use nutrients such as phosphorus. The results were increased productivity and improved fisheries. Since most states attempt to establish nutrient TMDLs to achieve a balance between nutrient and plankton that maintains fish productivity, this information should prove quite valuable.

Technical Abstract: Agricultural activities are considered to be a major source of nonpoint source pollution in the United States. The Clean Water Act requires states to improve water quality by setting Total Maximum Daily Loads of such pollutants as sediment, nutrients and pesticides. A common approach for setting nutrient levels is to use chlorophyll ' phosphorus relationships. Unfortunately these relationships will not necessary be valid in light limited lakes damaged by sediment. Analysis of total phosphorus, total sediment and chlorophyll concentrations indicate significant relationships between all three water quality parameters in three Mississippi Delta oxbow lakes. Total phosphorus and total sediment concentrations were positively correlated, while total phosphorus and chlorophyll a were negatively correlated. While this relationship seems counterintuitive further analysis indicates that when suspended solids is less than 150 mg/L there is a positive significant relationship between chlorophyll a and total phosphorus. When suspended solids exceed 150 mg/L there is a negative significant relationship between chlorophyll a and total phosphorus. This information should prove useful to water resource managers responsible for establishing TMDLs and water quality criteria where both sediments and nutrients cause impairment.

Last Modified: 9/1/2014
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