Coastal Oil Drilling Produced Waters: Chemical Characterization and Assessment of Genotoxicity Using Chromosomal Aberrations in Cyprinodon variegatus

Abstract

Oil drilling operations generate very large volumes of produced waters which contain a complex mixture of sub-surface water and solid and liquid geological materials, including crude oil, drilling fluids, and treatment chemicals. In coastal regions, these produced waters are discharged into fresh or brackish marshes or wetlands which also serve as the spawning sites for a wide variety of economically important species of fish and shellfish. Recently, concern has focused on potential impacts of produced waters upon these productive and sensitive ecosystems. In the present study, we report the results of investigations which characterize the chemical contaminants present in produced waters and surficial sediments collected at two sites in coastal Louisiana. Trace organic analyses of the produced waters revealed a complex and variable mixture of normal-, alkyl-, and heterocyclic polynuclear aromatic hydrocarbons. Examination of surficial and sub-surface sediments demonstrate that extensive areal distribution of the produced water hydrocarbons has occurred through time. Embryonic stage genotoxicity bioassays of the produced waters indicate that the polycyclic aromatic hydrocarbons being discharged in these coastal waters cause increased mutational frequencies in Cyprinodon variegatus. Since the observation of chromosomal aberrations is usually rare in the cells of the organism and since cell replication and differentiation are maximal in the early developmental stages of these and other species of aquatic organisms, the results suggest that the potential exists for adverse effects of these discharges on estuarine productivity. Further study of the impacts of produced waters in this and other species is indicated.

Heritability of resistance to individual contaminants and to contaminant mixtures in the sheepshead minnow (Cyprinodon variegatus)

“…Heritability estimates were obtained for a natural population of the sheepshead minnow ( Cyprinodon variegatus ), with resistance being quantified from bioassays with zinc and phenanthrene, both alone and in equitoxic combination, and from bioassays using a mixture of naphthalene, phenanthrene, dibenzothiophene, zinc, barium, and nickel. The latter six contaminants were used at the ratio in which they occur in sediment in a brackish marsh contaminated by produced water discharges and inhabited by C. variegatus [22–24].…”

Toxicity identification evaluations of produced‐water effluents

“…Produced water (PW), that is, subsurface formation water coproduced during oil and gas production, is one effluent that is permitted under the National Pollutant Discharge Elimination System (NPDES) for discharge into offshore waters and can exhibit both acute and chronic toxicity in laboratory testing [1,2]. In the past, the approaches to identifying causes of PW toxicity have involved direct chemical analysis of the whole PW with inference of toxicity made directly from the chemical composition of the effluent [3][4][5][6][7][8].…”

Mutagenicity assessment of produced water during photoelectrocatalytic degradation

“…However, large amounts of produced water are also discharged directly into the environment after only simple treatment. Previous studies indicated that this type of produced water contains chemicals that can cause acute and chronic toxicity in laboratory testing [3–6]. Furthermore, the increasing number of ecological accidents stemming from crude oil residues has been linked to the complex composition of produced water [7,8].…”