Acute Toxicity of Drilling Fluids Used in Mexican Offshore Facilities Tested with Postlarvae White Shrimp (Litopenaeus Setiferus)

摘要

Environmental standards for the regulation of drilling fluidsrnused in petroleum facilities, land or offshore, do not exist inrnMexican legislation, specially their toxicity limits. Thus, typernand quality of these products and their toxicity are unknown,rnmainly those of oil constituents, which are highly toxic tornaquatic biota and their early life cycles. In this study the LC50rn(96 hours) of different drilling systems (generic fluids andrnfield muds) using white shrimp (Litopenaeus setiferus) inrnpostlarvae stage were evaluated. This organism was selectedrnbecause its regional distribution and economic importance.rnAlso Mysidopsis bahia was used, only for comparing results,rnfor assessing generic fluids because is applied as referencernspecie by USEPA. In order to know the white shrimprnsensitivity, and its potential to be used as reference specie inrnMexico, additional tests using Sodium dodecyl sulfate werernrun. A toxicity test procedure using L. setiferus is presented.rnResults with both species shown similar responses to genericrnfluids evaluations. Only one generic fluid was toxic for bothrnspecies while the others did not. In case of field muds onlyrntwo were toxic to L. setiferus because they were formulatedrnwith oil. It is recommended to include Litopenaeus setiferusrnpostlarvae as a reference specie in Mexican Regulations forrndrilling fluids due to its distribution in Mexican petroleumrnoffshore facilities and because of its replication and highrnsensitivity (similar to Mysidopsis bahia) in toxicity tests.