USGS Atchafalaya and Mississippi River Deltas Study Proposal

Home |Atchafalaya & Mississippi River Deltas | Project Proposal - Task 4

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Task 1

GEOLOGIC DIVISION CONTINUING PROJECT WORK PLAN - FL 2001

Task: 4

Task Leader: Kvenvolden, Keith A. BLDG. 15, McKelvey Building 345 Middlefield Road Menlo Park, CA 94025 Phone: (650)329-4198 Fax: (650)329-5441		Task Leader: Rosenbaur, Robert J. BLDG. 15, McKelvey Building 345 Middlefield Road Menlo Park, CA 94025 Phone: (650)329-4198 Fax: (650)329-5441

Task Leader: Lorenson, Thomas D. BLDG. 15, McKelvey Building 345 Middlefield Road Menlo Park, CA 94025 Phone: (650)329-4198 Fax: (650)329-5441		Task Leader: Orem, William H. 12201 Sunrise Valley Drive Reston, VA 20192 Phone: (703)648-6273 Fax: (703)6486419

Title: Organic Chemical Contaminants in the Mississippi River Delta System

Task Priority: 1
Programs from which Fiscal Support is Solicited:

Coastal and Marine Geology Programs

Task Summary and Objectives:

Molecular markers for organic chemical contaminants are either geogenic (natural) or anthropogenic (non-natural/artificial). Geogenic markers are mostly compounds related to fossil fuel utilization and include petroleum and coal and their by-products. Anthropogenic markers are usually synthetic compounds, many of which are endocrine disrupting chemicals (EDCs), including pharmaceutical and personal care products (PPCPs, a newly identified environmental concern). A laboratory/field study will be undertaken to identify the principal geogenic and anthropogenic contaminants in the bed-load and suspended sediment of the Lower Atchafalaya and Mississippi Rivers. These contaminants will be investigated from the point of view of their fate as they pass from the terrestrial to marine environment in the Gulf of Mexico, and their recycling and resuspension in the near and offshore zone.

Work to be undertaken during the proposal year and a description of the methods and procedures:

During the first proposal year we will collect bed-load sediment samples from two study area utilizing a multicorer as part of a multidisciplinary approach to understanding the contaminant history of the Lower Atchafalaya and Mississippi Rivers. One core from each multicore station will be frozen immediately for organic contaminant studies. In the laboratory, these cores will be thawed, extruded, dried, and extracted. The extracts will be fractionated by chromatographic techniques, following standard procedures whenever available. The principal geogenic and anthropogenic contaminant markers will be identified by gas chromatography/mass spectrometry, and identifications will be based on computerized mass spectral library comparisons. In parallel to the laboratory work, a search of the literature, including reports by EPA and NOAA, will begin to establish the expected sources of contamination in the Mississippi River system.

During the second and third proposal years, bed-load sampling and analysis will be completed, and suspended sediment sampling and analysis will be undertaken. In the fourth proposal year, the fate of the most important identified contaminants will be investigated and compared in the Lower Atchafalaya and Mississippi Rivers. Efforts in the fifth proposal year will be directed toward a synthesis of the findings to yield a new understanding of the history of organic contaminants passing from the terrestrial to the marine environment in the Mississippi Delta. In addition, the information obtained on organic contaminants will be integrated with other geochemical and sedimentological data obtained from parallel Tasks of this project during the second through fifth proposal years.

Planned Outreach:

This project links to the national project "Geochemical Processes of Coastal Contamination" where the laboratory investigations of coastal contaminants will be done. This linkage will provide coverage of a significant portion of the U.S. coastal Gulf of Mexico, as one of five coastal regions under study in order to understand better the geochemical processes of coastal contamination of the shorelines of the United States. A series of publications is planned as progress reports toward a final synthesis in the fifth proposal year.

Publications delivered/completed for this Task:

Publications planned for this task, to be submitted for publication in current or future fiscal years.

Orem et al, 2002, Historical reconstruction of organic contaminants in the Mississippi and Atchafalaya river deltas.
Kvenvolden et al, 2002, Organic pollutants in large river plumes.

Geographic area of task:

United States, Gulf Coastal States, MS

Accomplishments

Current year nonpublication accomplishments and outcomes:

(All) March 2001 field trip completed successfully. Cores from the lower Mississippi and Atchafalaya Rivers collected for geochronology, general organic geochemistry, organic contaminant geochemistry, inorganic and nutrient geochemistry, and porewater geochemistry. River sampling for organic contaminants in particulates also completed. Geophysical surveys of bottom sediments also completed.

(All) Second field trip for sediment coring and other sampling farther offshore (shelf) of the Mississippi Delta planned for September 4-10, 2001.

(Orem) Completed analysis of C1-C6 hydrocarbons, organic and inorganic carbon, total nitrogen, and total phosphorus from four sites in the lower Mississippi and Atchafalaya Rivers collected in March 2001. Results indicate that upper sediment layers are highly dynamic. Completed analysis of porewaters for nutrients and major anions. Work on organic contaminants in sediments underway. Initial focus on polycyclic aromatic hydrocarbons and lignin phenols. This will address the question of whether natural aromatic substances in the environment influence the distribution of anthropogenically-derived aromatic hydrocarbons. Fatty acids in sediments will be used as markers of historical changes in the microbial community resulting from both climate change and anthropogenic contamination.

Highlights - summary of the most significant outcome:

Initial field trip completed successfully. Multiple cores collected at 4 sites established in the discharge zones of the Mississippi and Atchafalaya Rivers. Second trip scheduled for September 4-10, 2001.
Organic contaminant studies currently underway in both Menlo Park and Reston. The Menlo Park groups focus is on petroleum hydrocarbons, black carbon, and pharmaceuticals and personal care products (PPCP's). The Reston groups focus is on polycyclic aromatic hydrocarbons (PAH's), lignin phenols, nitrogen-containing aromatic substances, nutrients, and fatty acids.
Two Mendenhall Posdtdocs are participating in the study. Sid Mitra (Menlo Park - Kvenvolden) is examining black carbon and PPCP's in sediment cores and particulates in the water column. Antonio Mannino (Reston - Orem) is examining fatty acids in sediments as indicators of historical changes in microbial communities in response to climate change and anthropogenic contamination.

New Directions or Major Changes for Proposal Year:

A new coring device is being designed to better facilitate coring efforts further offshore.
New approaches for porewater extraction for contaminant studies are being developed based on experience gained from the first trip. These new approaches incorporate both whole core squeezing and centrifugation to obtain greater volumes of sediment porewater for contaminant studies.
The September field trip will establish several new sites farther offshore of the Mississippi delta, and an upriver lake site of continuous sedimentation. This will provide upriver and offshore endmembers to our already established sites inshore.