Microbial Response Law Of Natural Biodegradation Of Chloralkane Solvents In A Petroleum Hydrocarbon Contaminated Shallow Groundwater

The petroleum would be long-term pollution sources of soil and groundwaterwhich come from process of exploration, mining, refining and transportation byaccident. Meanwhile, petroleum would be serious harm to human health and ecologicalenvironmental of soil and groundwater because of its toxicity and carcinogenicity. Sopetroleum pollution have been became one of the most serious global environmentalproblems. Research on Microbial Response Law of Natural Biodegradation ofChloralkane Solvents in a Petroleum Hydrocarbon Contaminated Shallow Groundwaterwill be contributed to understand environmental behavior and biodegradationmechanism of Chloralkane Solvents in groundwater, then supply scientific foundationof building Chloralkane Solvents control and management technology in similarcontaminated sites.This paper was based on the project of “Distribution, migration and transformationof typical petroleum pollution in groundwater—case study in a certain oilfield innortheast China”, selecting a oil pipeline leakage area as study area, analyzingcontamination characteristics of soil and groundwater to identify CH2Cl2, CHCl3asfeatured pollutants, then study the Response Law of Natural Biodegradation ofChloralkane Solvents systemically. Theses study shows that:Characteristics of contaminated groundwater and soil in contaminated site(1) Based on68surface soil samples and50drilling soil samples which wereobtained from contaminated site and surrounding area,10mg/kg is appropriate for thelocal TPH background (threshold) concentration in soil of contaminated site using theCumulative Probability Plots, monitoring cross section method and analogue method.Overall surface soils TPH concentrations have a high spatial variability，showingsignificant point source pollution characteristics． For the longitudinal section soils，most of the high contamination level soil samples assembled in the soil layer at0-0.2m，below these layers the TPH concentrations are almost in the background (threshold) concentration scope.(2)According to the status evaluation and risk evaluation of organic pollution of theshallow groundwater of contaminated sites of the results, dichloromethane andchloroform pollution are the worst situations. Their nature is similar. Their leachingmobility in the aquifer than any other organic matter which is the greatest risk ofgroundwater pollution.(3) Anglicizing the quantitative test data of organic matter which in the pollutionsources and pollution sources’ downstream groundwater and sampling TPH data of soilstratified, and we can get a conclusion that the main way of groundwater pollution isdirect transmission, and supplemented by vertical leaching pollutionHydrogeochemical response law of natural biodegradation of chloralkane solventsThe analyses for the spatial and temporal variation characteristics of shallowgroundwater chemical index in the pollution field show that: in June2010, after theaccident happened about1year, in ZK1-ZK3-ZK6longitudinal section, the waterchemical components (Fe2+, Mn4+, SO42-) which act as electron acceptors forbioremediation, and the main physicochemical index (pH, Eh), which indicate thegroundwater environment, both have increased from upstream to downstream. Howeverthe first matrix (CH2Cl2, BTEX) and related reduction product (HCO-3) have decreasedfrom upstream to downstream. In June2010, the evaluation of chlorinated solventsnatural biodegradation indicates that for ZK1observation Wells, there are enoughevidences of microbial degradation; for ZK3observation Wells, the evidences ofmicrobial degradation are limited; for ZK6observation Wells, the evidence of microbialdegradation is insufficient. And in May2011, about2years after the accident, Thesealing pollution sources have moved to downstream with the center of the pollutiondizzy, the degradation in ZK3observation Wells is more and more obvious, thegroundwater chemical index in ZK3-ZK6longitudinal section presents the responsepatterns, and in ZK1observation Wells, many chemical indexes are gradually incline tobackground values before pollution with the supplement of the unpolluted upstreamwater.Microbial community response law of natural biodegradation of chloralkanesolvents Research of soil-groundwater Ecological structure and function characteristic havebeen preceded in different points and depth with application of PCR-DGGEFingerprinting Technology, to learn microbial community response law of naturalbiodegradation of chloralkane solvents. The main results show that:(1) Learn from analysis of α diversity index, community diversity of backgrounddrilling declined from0.2m to0.5m in aeration zone, then rise from0.5m to1.0m intransitional zone of unsaturated zone to saturated zone to the pick value, after thendecline to the constant value in saturated zone. Different pollution level affectCommunity diversity, but it is not a simple negative correlation. Severe pollution levelmakes community diversity reduce, but moderate pollution levels make it rise.(2) Learn from β diversity index, the community can be classified as three majorcategories at the background drilling indicate different depth represent different habitat.Both petroleum pollution and lithological changes affect β community diversity; makesome changes in classification of different depth at contaminated drilling.(3) Analyzing total activity by using qCO2, we know that it decreased with the soildepth in vertical section; in the ZK1-ZK3-ZK6horizontal section, the qCO2show ZK3〉ZK6〉ZK1that means total activity of moderate polluted site is bigger than backgroundsite, then background site bigger than severe polluted site.(4) Analysis of the sequencing result, after changing the community structure andpopulation, in the study area groundwater-soil environment effected by oil pollution,there is distribution of many oil-related microbial populations, such asmethane-oxidizing bacteria, petroleum oil degradation bacteria etc, and its content isrelatively abundant in seriously polluted areas. The rubber cutting sequencing, due to alot of DGGE fingerprint bands, not all were sequenced, but there will be characteristicsof pollutants-degrading bacteria chlorinated solvents, and it content with a certainregularity in the ZK1the-ZK3-ZK6section and the vertical profile.