Risk assessment of groundwater pollution in jilantai salt lake basin in arid area of Inner Mongolia
In order to clarify the chemical pollution characteristics of shallow groundwater in Jilantai Salt Lake Basin,Alxa League,Inner Mongolia,and to assess the safety risk level of groundwater drinking water,56 samples of soil surface(0-10 cm)and 127 samples of groundwater in the Salt Lake Basin were collected to detect and analyze typical heavy metals in soil.The content of elements Cu,As,Pb and the content of Cr,Hg,As,F-,NO2-,NO3-in the water sample.By using a conceptual model of groundwater risk assessment,the groundwater fragility,the capacity of groundwater toxic pollutants,and the potential ecological risk hazards of soil toxic pollutants are organically combined to carry out key assessments of groundwater pollution risks.Using ArcGIS software to perform Kriging interpolation mapping,the spatial distribution characteristics of shallow groundwater risk in the Salt Lake Basin were analyzed.The results show that the groundwater vulnerability index in the salt lake basin ranges from 4.80 to 5.30,which belongs to medium vulnerability,and the vulnerability of the southeast of Jilantai Salt Lake and the northwest of Jilantai Town is higher than that of other areas;The content of heavy metal Hg in groundwater samples is within the standard range,and other elements are beyond the standard.Among them,F-exceeds the standard rate of 62.20％in the sample.The coefficients of variation of Cr,As,F-,NO2-,and NO3-are respectively.It is 125.40％,183.50％,178.70％,248.70％,and 280.70％,which belong to strong variability and are obviously interfered by external factors.The distribution of groundwater characteristic pollutants in the study area is relatively concentrated,mainly in the southeast of the Salt Lake Basin;The average contents of heavy metals Cr,Hg,and As in the soil were 26.32,0.17,and 11.77 mg·kg-1.Compared with the local soil background value in Inner Mongolia,the average value of Cr was within the range of the background value,and the average value of Hg and As exceeds the background value by 4.25 and 1.57 times.The soil comprehensive potential ecological hazard coefficient is 188.32,which belongs to the medium potential ecological hazard,and 41.07％of the sample points in the Salt Lake Basin belong to the medium,strong and very strong potential ecological hazard;The uneven distribution of groundwater pollution risk in the Salt Lake Basin is related to the aquifer vulnerability index,characteristic pollutant capacity index and potential ecological hazard index.,the higher pollution risk area and the high risk area are distributed in the west of Xilingaole Town,and the area above the higher risk accounts for 25.77％of the regional area.The southeastern part of Gulaben Aobao Town and Helan Mountain is in the medium risk range,and the medium risk area accounts for 11.49％of the regional area.
salt lake basingroundwaterpollution assessmentspatial distributiontoxic pollutants
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