Experiment Study On The Biotoxicity Effects Of Coalbed Methane Produced Water

Over the past decade, the development of coalbed methane in China has entered into the commercial stage, and the mining scale and intensity increases rapidly. Environmental effect and water protection has become one of the important issues concern during CBM production. Based on the southern Qinshui coal Basin Shizhuang selected as the research region, based on analysis and evaluation of the quality characteristics of CBM produced water, this paper discussed the damage of CBM produced water to the genetic material by micronucleus test. By acute and subacute toxicity tests carried out on Carassius auratus by using CBM produced water, the effects of CBM produced water on fish growth and antioxidant enzymes was researched. Final conclusion is incloded:(1)The water quality characteristics of CBM water in the research region is high salinity and fluoride. The content of trace elements in water samples like fluoride, total iron, total manganese is overweight. Produced water after return has salinity of 4125.4~4965.1mg/L, and main salt was Cl~Na, with high organic content. Produced water during production has salinity of 687.1~1613.7mg/L with high fluoride, iron, manganese and ammonia, while main salt was HCO3~Na, part salt HCO3-Cl~Na.(2) Micronucleus test showed that frace-flow water had high concentration of toxic materials and mutagenic factor, that may damage the genetic mechanisms of biological cells, while produced water had low concentration of toxic materials and mutagenic factor, that may not damage the genetic mechanisms of biological cells.(3) Acute toxicity of CBM water in the frac-flow stage to Carassius auratus had been conducted. 24 h LC50、48h LC50、72h LC50 and 96 h LC50 calculated by modified Karber’s method are 0.234%、0.222%、0.211% and 0.207%,and security concentration is 0.021%. The results calculated by probit method are 0.236%、0.220%、0.208% and 0.203%, and security concentration is 0.020%.After 24 h short-term exposure, in the gill tissues of Carassius auratus, SOD activity of 0.164% concentration of the test group was significantly inhibited, while SOD activity in other concentrations were subject to significant induction. CAT activities of the groups were significantly inhibited. POD activity was subject to different degrees of induction or inhibition. In the liver tissues, SOD activities and CAT activities of the groups were induced in different degrees. POD activity was subject to different degrees of induction or inhibition. POD activity was induced to maximize at concentration of 0.130%.(4) CBM produced water of production stage has different degrees of inhibition on the growth of Carassius auratus. Howere, there were no significant differences between high and low concentrations of produced water in inhibiting the growth of Carassius auratus.In the gill tissues of Carassius auratus, SOD activities in the two treatment groups were the first decline after rising trends, and were significantly induced or inhibited. CAT activity’s trend of the half-dose group was downward after the first rise, while CAT activity of the concentration group presented whole fluctuation. CAT activities of the two treatment groups had different degrees of induction or inhibition. POD activity of the concentration group in the whole entire experimental period was suppressed. POD activity of the half-dose group presented declining trend. POD activity was induced by the first longer be inhibited.In the liver tissues of Carassius auratus, SOD activity of the concentration group increased at first and then decreased again rised. SOD activity of the half-dose group was the first decline after rising trends. SOD activities in the two treatment groups were significantly induced or inhibited. CAT activities of the groups presented declining trend. In the whole entire experimental period, CAT activities of the two treatment groups were suppressed. POD activities of the two treatment group increased at first and then decreased again rised. POD activities had different degrees of induction or inhibition.These results indicate that the pollution components of CBM produced water contain mainly fluoride, iron, manganese and toxic and hazardous organic substances. The CBM water draining without treatment will make pollution threat to the surrounding soil, surface water and groundwater, at the same time it would pose a threat to the biological in the contaminated area.