The Study Of Characteristics And Cause Analysis Of Karst Fissure Water System Petroleum Hydrocarbon Pollution In The Western Area Of A City

As a kind of important energy petroleum hydrocarbons has an irreplaceable role in the industrial production and other fields.But due to the ways of run, risk, drip, leak phenomenon is serious in the process of production and transportation, caused great influence to the surrounding environment, polluting the atmosphere and soil, at the same time,the petroleum hydrocarbons polluted the groundwater through the way such as rainfall infiltration, groundwater pollution.What is more,it can cause huge economic losses, so the sources, distribution and cause analysis of petroleum hydrocarbon in groundwater are particularly important.A petroleum chemical industry, machinery manufacturing, and many other enterprises are distributed in the western of the city, the petroleum hydrocarbon pollution of groundwater is more serious.Choosing the area as the research area is not only can fully demonstrate the distribution characteristics of the petroleum hydrocarbon pollution, but also to provide the basis for local government to formulate relevant water quality environment standard.By surveying the hydrogeological conditions, select 22 sampling point to analyze.Combined with the historical hydrologic geological data, it is concluded that the spatial distribution characteristics of petroleum hydrocarbon contaminated karst fissure water, make the source apportionment of petroleum hydrocarbon, and then carry out the study of pollution causes.The main conclusions are as follows:(1) The spatial distribution features of petroleum hydrocarbon pollution of groundwater in the study area.In the presence of pollution sources, the area of petroleum hydrocarbon is the biggest in 1991, polluted the J20 is the center of pollution, petroleum hydrocarbon migration, round concentration decreases.Petroleum hydrocarbons are migrating far and near, the concentration is becoming smaller and smaller.The migration is the fastest along the groundwater flow direction, the shape of pollution is becoming approximate ellipse,which is long and narrow, long axis and groundwater flow direction.The flow direction of long axis is the same as groundwater's.After cutting off the pollution sources, monitoring datas of 1996, 1998, 2007 and 2015 show as follows:Affected by groundwater hydrodynamic field, pollution plume is moving to the downstream migration,J11 is as the center of pollution, the contaminant plume of petroleum hydrocarbon is stable in the downstream.Showing that the plume area is smaller, the concentration of petroleum hydrocarbon of monitoring hole is smaller and smaller in the study area. The dry reason compared with the wet reason, the concentration of petroleum hydrocarbons is high and the contaminated area is less on the dry reason.The concentration of petroleum hydrocarbons is low and the contaminated area is more.(2) Based on all the data of sampling points in the study area,Based on all the data of sampling points in the study area,using cluster analysis and SPSS software to make qualitative identify chlorinated hydrocarbon pollution sources, to determine the pollution source of number and kind groundwater in the study area and species.And calculate the contribution rate of various pollution sources, the results show that a certain refinery were the main pollution sources, the contribution rate is as high as 68.26%.(3) The causes of petroleum hydrocarbon pollution of groundwater in the study area Studies have shown that human activities is the main source of petroleum hydrocarbons in the study area.The unreasonable industrial layout, long-term seepage discharge pipes, sewage waste water infiltration of water storage tank,the ways of run, risk, drip, leak phenomenon in the process of production,are the main source of petroleum hydrocarbons in the groundwater in the study area.The nature of the vadose zone decide that witch the pollutant can go into the groundwater or not.The south of the study area is the ordovician limestone,whose permeability coefficient of the vadose zone is bigger, soil resistance is very poor,the pollution is easier to enter into the groundwater.(4) The causes of distribution of petroleum hydrocarbon of groundwater in the study area.The direction of the groundwater flow field and water velocity determine the distribution characteristics of petroleum hydrocarbons in the groundwater in the study area.The migration of pollutants in groundwater was from southeast to northwest by the migration of flow field in the study area.There is magmatic rocks in the northern study area, which can be used as a block water rock mass.As a result, the distribution of petroleum hydrocarbon pollution plume in northern is relatively stable which migrate Slowly.The changes of water level in the study area determine distribution characteristic of petroleum hydrocarbons in wet reason and dry reason.In dry reason, the rainfall is small,the groundwater levels falls down, the concentration of petroleum hydrocarbon increase, because of the water level drops, the pollution area is reduced.In wet reason, the rainfall is more, so the concentration of petroleum hydrocarbon is reduced, he pollution area is bigger.Dilution of groundwater system,the roles of leaching, adsorption and dissolution make important influence on the distribution of petroleum hydrocarbon in the karst fissure water system.In addition,the change of the chemical field of groundwater is also the important cause for the distribution Characteristics of the petroleum hydrocarbon pollution of groundwater in the study area.