U.S.
GEOLOGICAL SURVEY
Water-Resources Investigations Report 03-4170—version 1.10
Concentrations and Distribution of Slag-Related Trace Elements and Mercury in Fine-Grained Beach and Bed Sediments of Lake Roosevelt, Washington, April-May 2001
Prepared
in cooperation with
CONFEDERATED TRIBES OF THE COLVILLE RESERVATION,
LAKE ROOSEVELT WATER-QUALITY COUNCIL,
BUREAU OF RECLAMATION, and
NATIONAL PARK SERVICE
By Michael S. Majewski, Sue C. Kahle, James C. Ebbert, and Edward G. Josberger
ABSTRACT
A series
of studies have documented elevated concentrations of trace elements such
as arsenic, cadmium, copper, lead, mercury, and zinc in the water, bed sediment,
or fish of Lake Roosevelt and the upstream reach of the Columbia River. Elevated
concentrations of some trace elements in this region are largely attributable
to the transport of slag and metallurgical waste discharged into the Columbia
River from a smelter in Canada. Although most recent studies have focused
on contamination levels in water, bed sediment, and fish, there is growing
concern in the region over the potential threat of airborne contaminants to
human health. In response to these concerns, the U.S. Geological Survey conducted
an assessment of trace-element concentrations in the relatively shallow
fine-grained sediment along the shore of Lake Roosevelt that is exposed annually
during periods of reservoir drawdown. During each winter and spring, the water
level of Lake Roosevelt is lowered as much as about 80 feet to provide space
to capture high river flows from spring runoff, exposing vast expanses of
lake-bottom sediment for a period of several months. Upon drying, these exposed
areas provide an extremely large source for wind-blown dust.
This study concluded that trace elements associated with slag and metallurgical waste are present in the fine-grained fraction (less than 63 micrometers) of bed sediments along the length of Lake Roosevelt, and as such, could be components of the airborne dust resulting from exposure, drying, and wind mobilization of the sediments exposed during the annual drawdowns of the reservoir. Trace-element concentrations in the surficial bed sediment varied, but the major components in slag—arsenic, cadmium, copper, lead, and zinc—showed generally pronounced gradients of decreasing concentrations from near the International Border to the Grand Coulee Dam. The results of this study provide base-line information needed to plan and conduct air monitoring of trace elements in wind-blown dust along Lake Roosevelt.
CONTENTS
Abstract
Introduction
Data Collection and Analysis
Concentrations and Distribution of Slag-Related Trace Elements and Mercury
Summary
References Cited
Appendix 1. Analytical results and relative standard deviations for duplicate samples and National Institute of Standards Technology reference material for quality control
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Send questions or comments about this report to the authors, Michael S. Majewski, (916) 278-3086 or Sue C. Kahle, (253) 428-3600 ext. 2616.
For more information about USGS activities in Washington, visit the USGS Washington District home page.
