Resurvey of Quality of Surface Water and Bottom Material of the Barataria Preserve of Jean Lafitte National Historical Park and Preserve, Louisiana, 1999-2000

Swarzenski, Christopher

The quality of water and bottom material in the Barataria Preserve of Jean Lafitte NationalHistorical Park and Preserve, Louisiana, was surveyed from March 1999 to May 2000. Organochlorine, chlorophenoxy acid, and organophosphorus pesticides; polychlorinatedbiphenyls (PCB’s); and trace elements were analyzed in surface water and bottom material fromthree sites previously sampled in a 1981-82 survey. Surface water at six sites was sampled andanalyzed for selected nutrients and major inorganic ions based on their importance to humanhealth, the health of the marshes of the Barataria Preserve, or their usefulness in tracking the circulation of Mississippi River water in the Barataria Preserve.Southern Louisiana was in a moderate to severe drought during most of the sampling period, which elevated salinity in the Barataria Preserve for at least 8 months. Specific conductancevalues were less than 3,000 μS/cm (microsiemens per centimeter at 25 degrees Celsius) insurface water throughout the Barataria Preserve from March through September 1999. Specificconductance values increased over the next 2 months and then remained between 5,000 and6,000 μS/cm.The herbicide 2,4-D was detected in water at the two sites sampled in August 1999 but not at any site during the two other sampling times. Iron, manganese, and the trace elements copper, nickel, and zinc were detected in dissolved and whole-water samples at all three sites. Nitrite+ nitrate, as nitrogen, concentrations ranged from less than 0.002 to 0.19 mg/L (milligrams per liter). Ammonia, as nitrogen, concentrations ranged from less than 0.01 to 0.16 mg/L. Orthophosphate, as phosphorus, concentrations ranged from less than 0.002 to 0.14 mg/L. Calcium, magnesium, potassium, sulfate, and chloride concentrations in surface water were elevated due to the marine influence on the composition of surface water in the Barataria Preserve during the sampling period. Sulfate and chloride concentrations reached 379 and 2,830 mg/L, respectively.Polychlorinated biphenyls, chlordane, and DDT were detected in bottom material. Traceelements were detected in bottom material at all three of the sampled sites. Arsenic concentrations ranged from 4 to 9 μg/g (micrograms per gram) and lead concentrations from 20 to 31 μg/g. Mercury concentrations also were above laboratory reporting levels (LRL’s) for bottom material at all three sites. Probable Effects Levels (PEL’s) and Interim Sediment Quality Guidelines (ISQG’s) concentrations, as tabulated by the Canadian Council of Ministers of the Environment, wereused to assess the probability of biological impairment in the Barataria Preserve. PEL’s areconcentrations of a chemical at or above which some biological impairment is likely. ISQG concentrations are those at or below which biological impairment is unlikely. Concentrations of2,4-D and trace elements, when detected in surface water, were substantially lower than levels at which biological impairment could be expected. Concentrations of organic compounds in bottom material were at most less than 25 percent of PEL’s, and usually much lower. Arsenic, cadmium, copper, and lead concentrations in bottom material were generally slightly above or lower than ISQG concentrations in both surveys, although arsenic was as high as 53 percent of PEL’s at one site in the 1999-2000 survey. All other trace elements in bottom material were present in concentrations lower than ISQG concentrations.

Resurvey of Quality of Surface Water and Bottom Material of the Barataria Preserve of Jean Lafitte National Historical Park and Preserve, Louisiana, 1999-2000

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