Study On The Derivation Of Soil Screening Levels Of Development Land In Liaoning Province

Soil screening levels(SSLs)are risk-based concentration of contaminants in soil They are used to identify areas of contaminated sites needing further investigation.At present,many countries have developed risk-based soil screening levels(SSLs),such as the United States,Netherlands,United Kingdom,etc.,but different countries have great differences in the names,values and the way of using SSLs,showing strong regional characteristics.Last year,China has issued mandatory national SSLs,but the geography and soil heterogeneity of the country are changeful.The use of uniform standards for management is bound to produce great uncertainty.In this study,Liaoning Province was selected as a typical region to research,through the priority pollutants screening,formula derivation,parameter acquisition,results calibration and uncertainty analysis,the derivation of SSLs of Liaoning Province was completed.The results and conclusions of this study are as follows:1)On the basis of collecting of priority pollutants lists,the environmental standards and the pollutants detected in the contaminated sites of Liaoning Province,a preliminary list of 158 pollutants was proposed,and then a statistical and literature analysis screening method was used to screen a list of 137 priority pollutants.2)After hazard identification and dose response assessment,the exposure scenarios for residential and industrial-commercial land use were constructed based on the land use norm and the Shenyang City Master Plan,and exposure pathways and sensitive receptors were identified.The SSLs calculation formulas were derived from the exposure assessment models in "Technical Guidelines for Risk Assessment of Contaminated Sites(HJ25.3-2014)".Data in the literatures were collected to get parameters by statistical methods and then the results were calculated3)By considering the soil background value,detection limit,soil saturation limit and theoretical ceiling limit,the results are corrected.The case verification is carried out by comparing with the maximum concentration of pollutants and showed that the values can play the role of screening.Compared with national standards and US regional screening levels,it shows that affected by parameters and methods the value has certain differences with other standards4)The Crystal Ball model based on Monte Carlo simulation was employed to analyze the uncertainty of parameters of SSLs.The results show that the soil screening levels of heavy metals and volatile organic compounds are lognormal distribution.The sensitive parameters affecting heavy metals are risk acceptable level,daily soil intake(IR),exposure frequency(EF)and exposure duration(ED).The sensitive parameters affecting volatile organic compounds are soil organic matter content(fom),soil bulk density(ρb),areal fraction of cracks in foundation/walls(η),and acceptable risk levels.