U.S. Geological Survey Toxic Substances Hydrology Program--Proceedings of the Technical Meeting, Colorado Springs, Colorado, September 20-24, 1993, Water-Resources Investigations Report 94-4015

Dissolved Organic Compounds in the Mississippi River from Minneapolis-St. Paul, Minnesota to New Orleans, Louisiana

Abstract

Dissolved organic contaminants were measured in water samples collected from the Mississippi River during four sampling surveys to assess spatial and temporal variability of these substances in the river. A hierarchical analytical approach was taken in which both broad spectrum and specific compound analyses were used. Specific indicators of sewage effluents included anionic surfactants and caffeine. These compounds were detected throughout the river, with maximum concentrations occurring near major cities. Other compounds such as volatile chlorinated hydrocarbons and ethylenediamine-tetraacetic acid, which are more indicative of industrial effluents, also were detected throughout the river. Specific organic compound concentrations in water were less than 50 micrograms per liter, and were controlled by a variety of environmental processes. Depending on the molecular structure of individual chemicals, they can be persistent in the Mississippi River or they can be removed by biodegradation, volatilization, or sorption.