Exposure and effects of oilfield brine discharges on western sandpipers (Calidris mauri) in Nueces Bay, Texas

Discharge of oilfield brines into fresh and estuarine waters is a common disposal practice in Texas. Petroleum crude oil (PCO) extraction from underground stores includes the removal of a significant amount of water along with the oil. Several methods may be used to separate the oil and water fractions, including tank batteries, heat separation, and skimming ponds. Disposal of the resultant produced water (oilfield brine) may be accomplished by deep-well injection or discharge to surface waters. In Texas, an estimated 766,000 barrels of oilfield brine were discharged daily into tidal waters in 1979. The maximum concentration for oil and grease in these discharges permitted by the Texas Railroad Commission is 25 ppm. Several studies have shown that oilfield brines are toxic to a wide range of marine life, yet little is known about their effects on birds and mammals. Exposure to petroleum in oilfield wastes could evoke toxicological effects in some waterbird species. Avian responses to PCO exposure are highly variable, including cessation of growth, osmoregulatory impairment, endocrine dysfunction, hemolytic anemia, altered blood chemistry, cytochrome P450 induction, reduced reproductive success, and mortality. Oilfield brine discharges may soon be the largest and most pervasive source of contaminants entering Texas estuaries. Migratorymore » and resident birds feeding in the vicinity of discharge sites may be ingesting food items contaminated with petroleum hydrocarbons, heavy metals and salts in sufficient quantities to evoke toxicity. The present study of wintering western sandpipers (Calidris mauri) that feed and roost near discharge sites sought to examine oilfield brine exposure and effects through quantification of contaminant burdens, morphological characteristics, and cytochrome P450-associated monooxygenase activities. 20 refs., 2 tabs.« less