钢铁厂遗留场地土壤重金属和多环芳烃的污染特征及健康风险评价

Pollution characteristics and health risk assessment of heavy metals and polycyclic aromatic hydrocarbons in soils of remaining site left by a steel plant

以某钢铁厂遗留场地为例,采集29个点位115个不同深度的土壤样品,分析10种重金属和8种多环芳烃(PAHs)的残留含量、分布特征及污染来源,并对超标污染物开展健康风险评价。结果表明,土壤中Cu、Pb、Sb、Co、V超出对照点浓度水平,PAHs中以(Chr)、苯并(a)芘(BaP)、苯并(a)蒽(BaA)的检出率较高(>45%),7种致癌性PAHs总和的平均值为6.30 mg/kg,局部质量浓度可达203.10 mg/kg。除Ni、Be、Co、V在饱和带土壤浓度较高外,其余重金属及PAHs含量总体均随深度的增加而下降。土壤污染物主要有3种来源,分别为交通和燃烧混合源、工业生产源以及成土母质源。与《土壤环境质量建设用地土壤污染风险管控标准(试行)》(GB 36600—2018)中第一类用地筛选值相比,As、Pb、Co、V等4项重金属以及BaA、苯并(b)荧蒽(BbF)、BaP、茚并(1,2,3-cd)芘(InP)、二苯并(a,h)蒽(DBA)等5项PAHs超标。超标污染物在居住用地条件下具有一定的风险,应实施土壤修复/管控工程以保障土地安全利用。

Taking the remaining site left by a steel plant as an example,115 soil samples from 29 sites at different depths were collected to reveal the residual contents,distribution characteristics and pollution sources of 10 heavy metals and 8 polycyclic aromatic hydrocarbons(PAHs).The health risk assessment of excessive pollutants were conducted.The results showed that the contents of Cu,Pb,Sb,Co and V in the soil samples exceeded the control levels,and for PAHs,the detection rate of Chr,BaP and BaA was relative high(>45%).The average value of 7 carcinogenic PAHs was 6.30 mg/kg,but it could reach 203.10 mg/kg in some areas.Except for Ni,Be,Co and V,which were shown in a high concentration in saturated soils,the concentration of the rest heavy metals and PAHs decreased with increasing depth.Three major sources of soil pollutants were identified as traffic and combustion sources,industrial production sources,and natural sources.Four heavy metals(including As,Pb,Co and V)and five PAHs(including BaA,BbF,BaP,InP and DBA)exceeded the first land screening value as specified in“Soil environmental quality-risk control standard for soil contamination of development land(trial)”(GB 36600-2018).The excessive pollutants had certain risks for the purpose of residential land use.Therefore,soil restoration/control projects should be implemented to guarantee the safety of residents on the land.