Abstract:Aquatic eco-toxicity of drilling fluid for petroleum exploration in Chad Lake oildom was evaluated and graded using Brachydanio rerio as the common biomarker in aquatic toxicology and the Misgurnus anguillicaudatus as the dominant species, by the methods of 96h acute toxicity test for aquatic organism and toxicity unit (TUa). The results showed that Sample 1 had no acute toxicity effects on B. rerio and M. anguillicaudatus,in contrast, Sample 2 had a low-level toxicity to both of them. The 96h LC50 of B. rerio and M. anguillicaudatus stressed by Sample 2 were 42,362mg/L and 50,861mg/L with the TUa 2.36 and 1.97 respectively.The comparison of the components of two samples showed that by the addition of an additive named JHBA-2(a kind of hypo-fluorescencent white asphalt), the toxicity of Sample 2 was many times higher than Sample 1.This indicates that JHBA-2 has a severe eco toxicity, thus it should be abandoned or substituted by something low toxic or nonpoisonous in research and development.
