乍得油区环保钻井液的水生生态毒性评价

Assessment on aquatic eco-toxicity of environment friendly drilling fluid in Chad Lake oildom

以国际标准组织(ISO)规定的淡水污染指示生物斑马鱼Brachydanio rerio和乍得湖区优势种泥鳅Misgurnus anguillicaudatus为实验对象,采用96h急性毒性试验,以96h半致死效应浓度(96hLC50)和毒性单位(TUa)为指标,对乍得油区石油勘探开发所用钻井液进行水生环境生态毒性评价及分级。实验结果表明,1号钻井液样品对斑马鱼和泥鳅基本无毒害作用,2号钻井液对斑马鱼和泥鳅均具有低水平毒性效应。2号钻井液对斑马鱼和泥鳅的96hLC50分别为42362mg/L、50861mg/L,TUa分别为2.36、1.97。对比发现,由于2号钻井液比1号钻井液多了一种添加剂——低荧光白沥青(JHBA-2),生态毒性即由无毒激变为低毒性,因此该添加剂具有明显的环境生物毒性,可在今后的研究开发中弃用或寻求低毒及无毒替代品。

Aquatic eco-toxicity of drilling fluid for petroleum exploration in Chad Lake oil- dom 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 Sam- ple 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 ad ditive 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 he abandoned or substituted by something low toxic or nonpoisonous in research and development.