Impacts from oil and gas produced water discharges on the gulf of Mexico hypoxic zone.
Shallow water areas of the Gulf of Mexico continental shelf experience low dissolved oxygen (hypoxia) each summer. The hypoxic zone is primarily caused by input of nutrients from the Mississippi and Atchafalaya Rivers. The nutrients stimulate the growth of phytoplankton, which leads to reduction of the oxygen concentration near the sea floor. During the renewal of an offshore discharge permit used by the oil and gas industry in the Gulf of Mexico, the U.S. Environmental Protection Agency (EPA) identified the need to assess the potential contribution from produced water discharges to the occurrence of hypoxia. The EPA permit required either that all platforms in the hypoxic zone submit produced water samples, or that industry perform a coordinated sampling program. This paper, based on a report submitted to EPA in August 2005 (1), describes the results of the joint industry sampling program and the use of those results to quantify the relative significance of produced water discharges in the context of other sources on the occurrence of hypoxia in the Gulf of Mexico. In the sampling program, 16 facilities were selected for multiple sampling - three times each at one month intervals-- and another 34 sites for onetime sampling. The goal of the sampling program was to quantify the sources and amount of oxygen demand associated with a variety of Gulf of Mexico produced waters. Data collected included direct oxygen demand measured by BOD5 (5-day biochemical oxygen demand) and TOC (total organic carbon) and indirect oxygen demand measured by nitrogen compounds (ammonia, nitrate, nitrate, and TKN [total Kjeldahl nitrogen]) and phosphorus (total phosphorus and orthophosphate). These data will serve as inputs to several available computer models currently in use for forecasting the occurrence of hypoxia in the Gulf of Mexico. The output of each model will be compared for consistency in their predictions and then a semi-quantitative estimate of the relative significance of produced water inputs to hypoxia will be made.
- Research Organization:
- Argonne National Laboratory (ANL)
- Sponsoring Organization:
- NETL; FE
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 959235
- Report Number(s):
- ANL/EVS/CP-117633
- Country of Publication:
- United States
- Language:
- ENGLISH
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Hypoxia in the Northern Gulf of Mexico
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Related Subjects
58 GEOSCIENCES
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
AMMONIA
ANOXIA
BIOCHEMICAL OXYGEN DEMAND
CARBON
COMPUTERS
CONTINENTAL SHELF
DISSOLVED GASES
EXPLORATION
GULF OF MEXICO
NITROGEN
NITROGEN COMPOUNDS
NUTRIENTS
OXYGEN
PHOSPHORUS
PHYTOPLANKTON
SAFETY
SAMPLING
SOLAR PROTONS
US EPA