The effects of oil well drill cuttings on soil and rice plant development (Oryza sativa) under two redox conditions.

Few studies have focused on the release of toxic elements from oil well drill cuttings and their effect on soil. The present study evaluated these effects using rice growth as the endpoint. Drill cuttings were collected from a Brazilian well and added in doses of 300, 3,000 and 6,000 mg kg(-1) soil, which was maintained at oxidized or reduced conditions. When the redox potential reached approximately -250 mV, barium concentrations were determined by geochemical fractionation. Overall, doses of 300 and 3,000 mg kg(-1) promoted plant development, while a dose of 6,000 mg kg(-1) inhibited it due to the associated increase in electrical conductivity and exchangeable sodium concentration. In addition, the lower redox potential promoted solubilization of barite from the drill cuttings, which increased barium absorption by plants and translocation to grain, posing a risk to human health.