Flood effects on the physical and chemical properties of bed sediments in the Mississippi River
- Geological Survey, Lakewood, CO (United States)
- Wisconsin DNR, LaCrosse, WI (United States)
The Upper Mississippi River is an impounded river system consisting of 26 locks and dams that create navigation pools which are known to trap and store sediment and some chemical contaminants. During 1991 and 1992 representative samples of surficial bed sediments were collected from the navigation pools. The samples were analyzed for particle size, total organic carbon (TOC), nitrogen, sterols, linear alkylbenzene sulfonates (LAS), polynuclear aromatic hydrocarbons (PAH), organochlorines, polychlorinated biphenyls (PCBs), and trace elements. Representative samples were collected after the flood in 1994 in an identical manner and analyzed by the same or comparable methods to determine the effects of the flood. Calculations and measurements indicated that frictional water velocities during the flood were not fast enough in any pool to re-suspend the cohesive surficial bed sediment (primarily fine silt and clay size fractions) and that the median particle diameter of the sediment was significantly (based on a paired t-test at the 95-percent level) coarser after the flood than before-especially in the downstream navigation pools. TOC decreased significantly after the flood and the greatest change occurred in the downstream navigation pools, which is consistent with the increase in particle size. There was no significant change in the pre and post-flood carbon:nitrogen ratio. Coprostanol levels increased significantly after the flood. PAHs remained essentially the same for all pools before and after the flood as did organochlorines such as chlordane, dieldrin, and PCB concentrations generally decreased in most pools. Pre and post-flood cadmium concentrations were below the detection limit, and mercury concentrations indicated no change; but lead concentrations had a significant decrease in the post-flood sediments and especially in the upstream navigation pools.
- OSTI ID:
- 398196
- Report Number(s):
- CONF-9511137-; ISBN 1-880611-03-1; TRN: IM9649%%404
- Resource Relation:
- Conference: 2. Society of Environmental Toxicology and Chemistry (SETAC) world conference, Vancouver (Canada), 5-9 Nov 1995; Other Information: PBD: 1995; Related Information: Is Part Of Second SETAC world congress (16. annual meeting): Abstract book. Global environmental protection: Science, politics, and common sense; PB: 378 p.
- Country of Publication:
- United States
- Language:
- English
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