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Title: TEMPORAL AND SPATIAL TRENDS IN SEDIMENT CHEMISTRY IMPOUNDED WITHIN A FLOOD CONTROL RESERVOIR: GRENADA LAKE, MS

Author
item BENNETT, SEAN - UNIVERSITYY AT BUFFALO
item Rhoton, Fred
item HSU, SHUMIN - UNIVERSITY AT BUFFALO
item Alonso, Carlos

Submitted to: Federal Interagency Sedimentation Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 1/5/2006
Publication Date: 4/2/2006
Citation: Bennett, S.J., Rhoton, F.E., Hsu, S., Alonso, C.V. Temporal and spatial trends in sediment chemistry impounded within a flood control reservoir: grenada lake, ms. Federal Interagency Sedimentation Conference Proceedings, April 2-6, 2006, Reno, Nevada. CDROM.

Interpretive Summary: The variability of bottom sediment chemistry determines the accuracy of assessments made relative to potential chemical contamination, source area composition, and sedimentation rates in water bodies. The distribution of several selected elements was determined for sediment cores collected from a large flood control reservoir. The data showed that these elements were strongly associated with the clay-size fractions in the sediment, and that the sediment chemical composition did not vary appreciably with depth or position within the reservoir. These results suggest that there has been no change in the chemistry of source materials or sediment delivered to the reservoir since impoundment, that best management practices designed to restrict the transport of clay-size particles will improve water quality in the reservoir, and that the chemical characteristics of these sediments can be accurately estimated with a relatively small amount of samples.

Technical Abstract: Sedimentation issues were examined in a relatively large flood control reservoir in a highly unstable, cultivated watershed. Collected sediment cores were analyzed for 137Cs and texture, which demarcated the as-built reservoir timeline, and the bulk chemistry of the sediments. The concentrations of select elements (As, Cu, Cr, Pb, Hg, and Zn) are positively correlated with clay content, and are not atypical for soils. Statistical analyses showed that since dam construction: (1) select element content concentrations normalized by clay and aluminum content do not vary vertically within each sediment core; and (2) depth-averaged concentrations of select element concentrations normalized by clay and aluminum show no spatial variation within the sediment impoundment. These results suggest that sediment-associated chemical loadings to this reservoir have remained nearly invariant in time and evenly dispersed within the impoundment.