Study On Pollution Characteristics Of Typical Pollution Sources Of Perfluorinated Compounds In Shallow Groundwater System

As a new type of persistent organic pollutant,perfluorinated compounds(PFCs)have been paid more and more attention.Because of the hydrophobic and oleophobic,it is widely used in surfactants,electroplating anti-fog agent,paint additives,daily chemicals,non-stick coating and many other areas.PFCs also have bioaccumulation and biotoxicity,which are potentially harmful to organisms.Because of the stable chemical properties and better solubility of PFCs,the unreasonable emissions during the production and use of the factories,PFCs are easily accessible to the shallow groundwater system and persistence,resulting in PFCs contamination.In this paper,the fluorine materials and fluorine chemical industrial park as the main research objectives,and the electronics industry,electroplating industry PFCs pollution characteristics were studied.Based on the hydrogeological survey of the target area,select the shallow groundwater sampling point to analyze,and the temporal and spatial distribution characteristics of the PFCs in the shallow groundwater of the fluorine materials and fluorine chemical industrial park,the electronic and electroplating industry were summarized.And then to carry out the study of PFCs pollution characteristics and pollution causes in shallow groundwater.The main contents and conclusions are as follows:(1)Study on characteristics of PFCs pollution in shallow groundwater system of fluorine materials and fluorine chemical industry park.In the study area,the lithology of the shallow groundwater system gas zone is dominated by silt.The lithology of the aquifer is mainly composed of silty sand and silt.The total concentration of PFCs in shallow groundwater were determined in the range of 0.007 to 411.44?g/L in the dry season,and the total concentration of PFCs were determined in the range of 0.01 to 822.87?g/L in the wet period.And the change of the concentration was obvious.There are 11 species of PFCs detected in shallow groundwater,which perfluorooctanoic acid(PFOA)is the main pollutant.Its detection rate is 100%.Using factor analysis and the fuzzy clustering analysis to cause of PFCs pollution of shallow groundwater in the study area of industrial enterprises are divided into chemical pollution sources,paper pollution sources and textile pollution sources in three categories.Based on the analysis of the distribution characteristics of 11 PFCs,the PFCs pollutants in the shallow groundwater system have significant regularity in spatial distribution.The eastern part of the study area,the plant 4 and the plant 5 area are the pollution center,along the shallow groundwater flow migration and diffusion,the concentration of PFCs decreased rapidly,the pollution was basically long and narrow oval distribution,long axis direction from east to west.In the western part of the study area,the plant 10 and the plant area 12 were pollution centers,and under the action of groundwater flow,they spread to the southeast.The pollution feathers were elliptical.PFCs pollutants in the time distribution has a clear regularity.The concentration of PFCs in wet season was higher than that in dry season in shallow groundwater.The change of groundwater level caused the temporal and spatial variability of PFCs in groundwater.Water level varies,the concentration changes are different,the two basically show a positive correlation.Near the source of pollution(water level change is small),the average concentration of shallow groundwater PFCs in the wet season is about 2 times of dry season.Away from the source of pollution(water level change is large),the average concentration of shallow groundwater PFCs in the wet season is about 4 times of dry season.As the region is generally affected by PFCs pollution,the pollution area which in the same concentration range of pollution area increased.Due to the precipitation in the wet season,the PFCs which in atmosphere and adsorption on gas zone by the settlement,leaking and dissolution into the shallow groundwater,and then causing intermittent pollution.In addition,the pollutant continued to discharge a large amount,resulting in a rapid increase in the concentration of PFCs in shallow groundwater.(2)Study on characteristics of PFCs pollution in shallow groundwater system of electronics and electroplating industry.In the study area,the vadose zone lithology of the shallow groundwater system is mainly composed of silty clay and silt,and the lithology of the aquifer is dominated by silt and fine sand.The detection of PFCs is PFOS and PFOA in shallow groundwater.In the spatial distribution.Z1 well is the pollution center of PFCs in the shallow groundwater in the area where the electronics factory is located,the.,and D1 well is the pollution center of PFCs in the shallow groundwater in the area where the electroplating factory is located.Under the action of shallow groundwater flow field,the diffusion rate is faster along the north and south direction,and the polluted feathers exhibit long and narrow distribution.The long axis direction is consistent with the shallow groundwater flow direction.In the time distribution.The concentration of PFCs in the shallow groundwater in the dry season was higher than that in the wet season,and the dry season pollution area is slightly less than the polluted area of the wet season.In the study area,the shallow groundwater flow is simple,and the PFCs entering the groundwater migrate along the groundwater flow and spread in the direction of the groundwater flow.The changes of PFCs in the temporal distribution are caused by the shallow groundwater level changes.In the dry season,the amount of precipitation and the shallow groundwater reduced.So the concentration of PFCs increases,the water level decreases and the pollution area decreases.In the wet season,the amount of precipitation and the shallow groundwater increased.So the concentration of PFCs decreased.And the pollution area expanded due to the water level increased.