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Publications and On-line Reports

The USGS Toxics program maintains a complete bibliography of publications produced by USGS researchers. This bibliography can be queried in a variety of ways. Try searching the toxics program bibliography using key words such as: hypoxia, hypoxic, Gulf of Mexico, nitrate, nutrient, or nitrogen.

An Assessment of Coastal Hypoxia and Eutrophication in U.S. Waters by Donald Scavia and others.

• This report responds to Congresses call for an “Assessment of Hypoxia” as described in the Harmful Algal Bloom and Hypoxia Research and Control Act of 1998 (“HABHRCA,” Title VI of P.L. 105 383, section 604(b)). The Assessment examines “the ecological and economic consequences of hypoxia in United States coastal waters; alternatives for reducing, mitigating, and controlling hypoxia; and the social and economic costs and benefits of such alternatives.” The Assessment further supports initial Congressional findings that a significant factor causing or contributing to harmful algal blooms may include excessive nutrients in coastal waters, and also, that harmful algal blooms and blooms of non-toxic algal species may lead to other damaging marine conditions, such as hypoxia (reduced oxygen concentrations), which are harmful or fatal to fish, shellfish, and benthic organisms.

"Predicting the response of Gulf of Mexico hypoxia to variations in Mississippi River Nitrogen Load" by Donald Scavia, Nancy Rabalais, Eugene Turner, Dubravko Justic, and William Wiseman, Jr.

• The effect of nutrient loading from the Mississippi Basin on the areal extent of the Gulf of Mexico Hypoxic Zone is investigated using a dissolved oxygen model. Results suggest that a 30% reduction in nitrogen loads may not be sufficient to reduce the average size of the hypoxia zone to 5,000 km².

"Nitrogen in the Mississippi Basin--Estimating Sources and Predicting Flux to the Gulf of Mexico" by Donald A. Goolsby and William A. Battaglin.

• A summary of important results from the Task Force Science Assessment Topical Report 3 and from more recent analysis of the relations between the flux of nutrients from the Mississippi River and the extent of the hypoxic zone in the Gulf of Mexico.

• Their analysis indicates that a 12% cut in fertilizer use over the 1960-98 time period, could have reduced nitrate flux to the Gulf of Mexico by 33%. Abstract

Both articles indicate that

• The flux of nitrate from the Mississippi River to the Gulf of Mexico has nearly tripled in the last 30 years.
• The principal source areas of that nitrate are streams draining largely agricultural watersheds in southern Minnesota, Iowa, Illinois, Indiana, and Ohio.

• The report describes the use of δ¹⁵N and δ¹⁸O isotope ratios of dissolved nitrate in water samples from the Mississippi River and its tributaries to determine the sources and transformations of that nitrate as it moves to the Gulf of Mexico.

• Results in this paper suggest that in-stream assimilation and not denitrification accounts for the small amount of nitrate loss in the lower Mississippi.