SOIL CONTAMINATION BY OIL AND GAS-DRILLING AND PRODUCTION OPERATIONS IN PADRE-ISLAND-NATIONAL-SEASHORE, TEXAS, USA

Soil samples from 18 oil and gas drilling and production sites located in Padre Island National Seashore were analyzed for contaminating sub stances associated with drilling fluids and petroleum products. The re sults of the investigation indicate that soil contamination from these sources is widespread and persistent but generally localized in the i mmediate vicinity of drilling and production activity. Sixteen sites w ere found to have elevated levels of four heavy metals (barium, chromi um, lead, and zinc), sodium, salinity, pH, and/or petroleum hydrocarbo ns. There was no discernible pattern of contamination between well sit es, indicating the variability of methods and materials used in the dr illing of individual wells and the occurrence of isolated spills and m aterials misuse. The levels of contaminating agents found do not repre sent immediate environmental threats, but the long-term cumulative eff ects of soil alteration and toxicants on organisms and habitats in the barrier island ecosystem is largely unknown. (C) 1995 Academic Press Limited