U.S. Department of the Interior
Minerals Management Service
Gulf of Mexico OCS Region

Technical Announcement

Historical Reconstruction of the Contaminant Loading and Biological Responses in the Central Gulf of Mexico Shelf Sediments

 OCS Study MMS 2003-063

The Minerals Management Service (MMS), Gulf of Mexico OCS Region, announces the availability of a new study report, Historical Reconstruction of the Contaminant Loading and Biological Responses in the Central Gulf of Mexico Shelf Sediments. 

This study documents changes in chemical contaminants and biological components of dated sediments from the central Gulf of Mexico continental shelf to evaluate the relative sources and concentrations, including trace metals, selected organic compounds, phytoplankton pigments, diatom remnants, and foraminifera.  The distribution of the selected trace metals and organic compounds suggests a chronic contaminant loading from the river itself, from oil and gas exploration in the Gulf of Mexico, perhaps from natural seeps in the area, and the chronological usage of chlorinated agricultural pesticides.  The temporal patterns in phytoplankton are consistent with the increased accumulation of diatom remnants in sediments.  The increasing pigments and greater concentrations in areas where hypoxia is more likely to occur indicate an increase in eutrophication or a worsening of hypoxia or both.  No definite relationship could be established between the contaminant concentration in sediments and the composition of foraminiferal assemblage.  Deformed foraminifera, one indicator of extreme chemical pollution, are not present in either of the cores.  On the other hand, the diversity and relative-abundance changes of foraminiferal species fit the model of progressively worsening seasonal hypoxia in the area.

This report is available only in compact disc format.  The discs are available from the Minerals Management Service, Gulf of Mexico OCS Region, at a charge of $15.00 by referencing OCS Study MMS 2003-063.  You will be able to obtain this report also from the National Technical Information Service in the near future.  Here are the addresses.  You may also inspect copies at selected Federal Depository Libraries.