Assessing Pollution Characteristics,Source And Risk Of TPH In Soil Of Lanzhou Petroleum Stations

In this study,Total Petroleum Hydrocarbon(TPH)in the soil of gas stations in Lanzhou City was used to analyze the spatial distribution of TPH at different depths(surface 0～0.5m,middle layer 0.5～1m,deep 1～2m)in 48 gas stations in Lanzhou City,and the spatial distribution of TPH at different depths was analyzed by ordinary kriging interpolation,and the pollution levels were compared.The factor detector model was used to analyze the influence of soil components on the vertical migration of TPH.Absolute principal component analysis-linear regression method(APCS-MLR model)was used to analyze the main pollution sources of TPH in soil and the contribution rate of each source,and the RAG-C human health risk assessment model was further used to evaluate the hazard quotient of TPH to human health.The results showed that:(1)The overall pollution level of soil TPH in gas stations in Lanzhou City is relatively light.The TPH content in the soil surface range of gas station in Lanzhou was0～3842mg/kg,and the average value was 194.08mg/kg;The TPH content in the middle range was 0～2169mg/kg,and the average value was 111.86mg/kg;The TPH content in the deep range was 0～139mg/kg,and the average value was 14.72mg/kg.Among them,the TPH content in the soil of the sampling point of 39#gas station is significantly higher than that of other points,but it is still lower than the TPH screening value and control value stipulated in China’s"Soil Environmental Quality Construction Land Soil Pollution Risk Management and Control Standard"(GB 36600-2018).(2)There are differences in the spatial distribution of TPH in the soils of gas stations in different layers.The spatial distribution characteristics of TPH content in soils in the study area were analyzed by ordinary kriging interpolation,and the results showed that the TPH content in the surface layer of gas stations in Lanzhou city showed an overall trend of high in the center and low around the center with the characteristics of 39~#sampling points;the spatial distribution of TPH in the middle layer had some similarity with that in the surface layer;TPH in the deep layer existed in the north and south of Lanzhou city at a few points with higher TPH concentration The vertical distribution of TPH in the soil is:surface layer>middle layer>deep layer;using the factor detector model to analyze the blocking effect of soil components on TPH,the blocking properties of different soil components are:silt>clay>fine sand>coarse sand.(3)The main sources of TPH in soil are:anthropogenic and sedimentation sources,migration sources and leakage sources.The principal component method(PCA)was used to analyze the main sources of TPH in soil,and the APCS-MLR model was used to analyze the contribution rate of each source.The results showed that the sources of TPH in the surface soil were mainly man-caused oil spillage,run-up,dripping and leakage,automobile exhaust emissions,and dry and wet deposition of oil vapor in the atmosphere and volatile petroleum hydrocarbons during the heating period,with a contribution rate of 46%.The sources of TPH in the middle soil were mainly the vertical migration of TPH in the top soil and the drip leakage at the connection of the oil pipeline,with a contribution rate of 21%.The sources of TPH in deep soil were mainly leakage from oil tanks and pipelines and vertical migration of TPH in upper soil,contributing 33%.(4)All 48 gas station sampling points and 45 gas station sites do not have TPH non-carcinogenic risk and do not cause harm to human health,of which 3 gas station soil TPH hazard quotient exceeds the acceptable level of non-carcinogenic risk,which will cause harm to human health.Among the six pathways of ingesting TPH pollutants in soil,the gaseous pollutant pathway(PHQiiv)from the lower soil inhaled in indoor air contributed the most.In the existing studies,there are few studies on the soil of gas stations in Lanzhou City,and the soil research on Lanzhou is mainly concentrated in farmland areas,mostly focusing on heavy metals,and there are few studies on the pollution of typical oil storage sites in gas station cities.Based on this,this study investigated and studied the pollution of 48 gas stations with the same business mode in various districts and counties of Lanzhou City,analyzed the pollution characteristics,spatial distribution and source of TPH in the soil of gas stations,and conducted human health assessment to explore the impact of TPH on human health in soil,so as to provide a certain theoretical basis for the exploration of soil environmental pollution in Lanzhou gas stations,and provide certain data support for the monitoring and control of soil environmental quality of gas stations in Lanzhou City.