The Use of a Weight-of-Evidence Approach in Assessing the Ecological Effects of Produced Water Discharge Offshore Nigeria

摘要

A weight-of-evidence (WOE) approach was used to evaluate whether produced water (PW) discharges in the Gulf of Guinea, offshore Nigeria were having an undesirable effect on the marine ecosystem. The Nigeria study comprised an evaluation of PW constituent fate and effects in biotic (tissue) and abiotic media (receiving water and sediment), and laboratory bioassays of PW effluent. Lines of evidence (LOE) included: 1) laboratory toxicity testing, 2) assessment of chemical constituent spatial and temporal trends, 3) background comparisons and 4) toxicological benchmark comparisons. The LOE were evaluated based on data quality, consistency, degree of severity, and relevancy, and then integrated to arrive at an overall conclusion. The WOE approach concluded that potential incremental ecological risks associated with the discharge of PW constituents were inconsequential and no unacceptable risks were predicted to occur beyond the prescribed mixing zone boundaries. The study demonstrated the value of the WOE approach in evaluating potential environmental effects such as those associated with oil and gas development and operations.