Assessment of Sediments from the Upper Mississippi River


The U.S. Geological Survey (USGS) has been monitoring the Upper Mississippi River (UMR) since 1987 to document the fate and transport of contaminants associated with sediments. The UMR is that part of the river upstream of the confluence with the Ohio River at Cairo, IL and consists of a series of 26 navigational pools created by a lock and dam system extending from Minneapolis, MN to St. Louis, MO. The navigational pools are shallow, lake-like areas which trap and store large quantities of fine-grained sediments during normal river flows. Concern with the redistribution of the river sediments in the UMR by: (1) measuring the concentrations of contaminants in sediments of the UMR, (2) evaluating the toxicity of sediments collected from the river, (3) determining the bioaccumulation of contaminants from UMR sediments using field-collected and laboratory exposed oligochaetss, and (4) determining the benthic community structure in fine-grain sediments within the river. To conduct these assessments, sediment samples and benthic organisms were collected from 24 of the 26 navigational pools in the river and from one pool in the Saint Croix River. Two types of sediment samples were collected from the pools. One sediment sample was a composite of 15 to 20 sediment grabs along one to five transects across the downstream one-third of each pool (B samples). The other sediment sample was a composite of grabs from one station on one transect within each pool (C samples). The latter stations were selected based on historical chemistry data and the potential to collect oliogchaetes. Samples were not collected from the main navigational channels. Chapter 1 of this report describes whole-sediment toxicity tests which were conducted for 28 days with the amphipod Hyalella azteca. Survival, growth and sexual maturation were the measurement endpoints. Toxicity tests were conducted with both the B and C samples. Chapter 2 describes the bioaccumulation studies conducted in the laboratory using field-collected oligochaets and 28-day bioaccumulation studies conducted in the laboratory with the oligochaete Lumbriculus variegatus. Bioaccumulation tests were conducted with 13 of the 24 C sediment samples. Chapter 3 assess the benthic community in all 24 C samples. Using the Sediment Quality Triad approach, the status of UMR sediments was assessed by integrating sediment chemistry, laboratory toxicity tests and benthic community measurements.


139 pages; available for download at the link below.


sediments, contaminant transport, Mississippi, sediment contamination