Toxicity of Drilling Waste from Oil Wells on Oligochaeta

摘要

The most abundant and critical elements in residues from well drilling and prospecting are barium and sodium. Ecotoxicological tests have been used to evaluate the toxicity caused by toxic substances present in the soil. The objective of the present study was to verify the effect of the application of drilling residue from oil wells on Oligochaeta activity. After incubation of the soil with residue doses – BaSO 4 and NaCl – three ecotoxicological tests were performed in which the species Eisenia andrei was used as a bioindicator. The avoidance behavior test showed that there was a negative effect of the application of the residue at a dose of 234 t ha -1 on Oligochaeta activity. However, the application of BaSO 4 alone did not show damage to the earthworms, unlike what was observed for NaCl application. These results indicate that sodium was the element that most restricted the activity of these organisms.