Environmental monitoring of offshore oil and gas drilling discharges—A caution on the use of barium as a tracer

Commonly used methods for extracting barium from marine sediments are inefficient when high concentrations of barium sulphate are present in samples. Comparative data on sea-bed barium concentrations around a single exploration well are presented to highlight the influence of different extraction methods which can result in 2–3 order of magnitude differences in levels recorded. This suggests that in many monitoring studies the value of barium as a tracer of discharged drilling wastes and thus as an aid to the interpretation of survey data is reduced. The environmental management implications of these findings are explored and a holistic and more collaborative approach to environmental effects monitoring is advocated.