Effects of oilfield brine effluent on sediments and benthic organisms in Trinity Bay, Texas
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Field studies have established the concentrations of naphthalenes in bay sediments and water in the vicinity of an oil separator platform and their effects on the benthic fauna. Fifteen stations were occupied monthly, from July, 1974 to December, 1975, along three transects extending from the separator platform outfall outwards for a distance of 4.0 to 5.6 km. A lesser number of stations were occupied from April, 1974 to June, 1974. Bottom sediments at each station were analysed for total naphthalnes content and for number of species and individuals. All stations were located in 2 to 3 m of water. The outfall was located 1 m off the bay bottom. There was a definite correlation between sediment naphthalenes concentration and number of species and individuals. As expected, the first station, located 15 m from the outfall, had the highest concentration of naphthalenes of all stations sampled. The naphthalenes levels dropped sharply from the outfall to the stations located 75 m from the platform where levels were about 20-50% of those found 15 m from the outfall. Naphthalenes concentrations then decreased gradually to near background levels at stations farther out. Hydrogen concentrations in bottom water 15 m from the outfall were three orders of magnitude lower than those in the full strength effluent, but sediments 15 m from the outfall had hydrocarbon concentrations four times as great as in the full strength effluent. There were approximately four orders of magnitude more hydrocarbons in the sediment than in the overlying water. The bay bottom was almost completely devoid of organisms within 15 m of the effluent outfall. Stations located 150 m from the outfall had severely depressed benthic.