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U.S. Department of the Interior
U.S. Geological Survey
Michigan Water Science Center


Prepared in cooperation with the U.S. Fish and Wildlife Service

Concentration and Spatial Distribution of Selected Constituents in Detroit River Bed Sediment Adjacent to Grassy Island, Michigan, August 2006

U.S. Geological Survey Open–File Report 2008–1016

By C.J. Hoard



This report is available below as a 21–page PDF for viewing and printing.


In August 2006, the U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service, collected sediment–core samples from the bed of the Detroit River adjacent to Grassy Island. The goal of the sampling was to assess the distribution and concentration of chemical constituents in sediment adjacent to Grassy Island, which was operated from 1960 to 1982 as a confined disposal facility to hold dredge spoils. On August 31, 2006, seven samples were collected at four locations in the Detroit River on the north, south, east, and west sides of the island. Metals concentrations in the riverbed sediment tended to be higher on the west side of the island, whereas organic–compound concentrations were generally higher on the east side. Comparison of results from this sampling to concentrations reported in previous studies indicates that the concentrations of inorganic constituents, mainly metals, in the riverbed sediment around Grassy Island fell within the range of concentrations found regionally throughout the Detroit River and in most cases have lower mean and median values than found elsewhere regionally in the Detroit River. Comparison of results from the August 31, 2006, sampling to U.S. Environmental Protection Agency risk–based sediment–quality guidelines indicates that 18 organic constituents for which an ecological screening level (ESL), and (or) a threshold effect concentration (TEC), and (or) a probable effect concentration (PEC) has been defined exceeded one or more of these guidelines at least once. Further work would be needed to determine whether constituent concentrations in the river sediment are related to constituent runoff from Grassy Island.



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Whole report (8.95 MB) – 21 pages (8.5” by 11” paper)



Suggested Citation:

Hoard, C.J., 2008, Concentration and spatial distribution of selected constituents in Detroit River bed sediment adjacent to Grassy Island, Michigan, August 2006: U.S. Geological Survey Open–File Report 2008–1016, 21 p. Date Posted: March 4, 2008: []






Flow Model and Sample–Site Determination

Sample Collection and Preparation

Data Analysis

Concentrations of Selected Inorganic Constituents

Concentrations of Selected Organic Constituents

Spatial Distributions of Selected Constituents



References Cited

Appendix. Boxplots of various chemical constituents sampled in riverbed sediment near Grassy Island, Michigan


1. Maps showing location of Grassy Island, Michigan, and sediment–sampling locations adjacent to the island.

2. Selected boxplots for lead (A) and pyrene (B) in sediment adjacent to Grassy Island, Michigan.


1. Concentrations of inorganic constituents in riverbed–sediment samples collected around Grassy Island, Michigan.

2. Concentrations of organic constituents in riverbed–sediment samples collected around Grassy Island, Michigan.

3. Location and list of constituents with concentrations greater than an effect concentration or screening level.


For additional information, contact:

U.S. Geological Survey
Michigan Water Science Center
6520 Mercantile Way, Suite 5
Lansing, MI 48911–5991


or for more information about USGS activities in Michigan, visit the USGS Michigan Water Science Center home page.


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