Study On Contaminantes Monitoring And Health-Risk Assessment Of The Contaminated Sites From Wuhan Qingjiang Chemicals Co. Ltd.

With rapid development of urbanization, large numbers of industrial enterprises, suchas chemical, metallurgy, electron industry and so on, have relocated or closed, leavingbehind quite a lot retired contaminated sites. The majority of these sites were seriouslypolluted with different hazardous heavy metals and toxic organic compounds, posing asevere threat to human health and eco-environment and bringing along with potentialenvironmental risk. Therefore, before fuctional transformation and re-exploitation of thesecontaminated sites, their contamination status should be investigated and health risk beassessed, in order to provide scientific reasons and guidances for risk management andremediation of these sites.In allusion to the to-be retired contaminated site now belonging to Wuhan QingjiangChemicals Co. Ltd., this paper has investigated its contamination state, evaluated thehealth risk to human beings, and proposed risk-based soil remedial targets of contaminants.The major contents and conclusions are summerized as follows:(1) Depending on preliminary site investigation, heavy metals and organic pollutantslike TPH, PAHs, dimethyl sulfate, methanol, were estimated as possible contaminants.Meanwhile, potential contaminated regions were plotted out.(2) Further investigation was performed by sampling and sample analysis. Physicaland chemical characters of the soil samples were analysed based on method GB/T50123-1999. According to relavent US EPA methods, both soil samples and groundwater samplewere analysed the contents of14heavy metals including stibonium (Sb), arsenic (As),beryllium (Be), cadmium (Cd), chromium (Cr), copper (Cu), elad (Pb), mercury (Hg),nickel (Ni), selemium (Se), silver (Ag), zinc (Zn), thallium (Tl), vanadium (V) and Cr6+,total petroleum hydrocarbons (TPH), volatile organic compounds, semi-volatile organiccompounds, methonal and dimethyl sulfate as well. In addition, referring to US EPATCLP, the foresaid heavy metals and Cr6+were detected in extrating solutions. It turnedout that the soils were mainly silt, floury soil and silty clay, and were primarilycontaminated by As, Pb, Cu, Sb and V, TPH, benzo[a]anthracene, benzo[a]pyrene,benzo[b]fluoranthene and Indeno[1,2,3-cd]Pyrene. Heavy metals were principally distributed in stacking area of iron ore concentrate located to the west, adjacent productionarea of1stplant, ore stacking area of3rdplant and SO2-production area, while the organiccompounds were mainly found in the production area of2ndplant. No contamination wasdetected at other regions.(3) Risk assessment was performed towards the above contaminates, and the resultsshowed that As contributed99.99%to carcinogenic risk and80.96%to hazard quotients,becoming the prior contaminant that need to be controlled. The remediations should becarried out in different areas, As contaminated soils in S2, S3and S18zone, Cu in S2, S3and S7zone, Pb in S2and S3zone, V in S6and S7zone, benzo[a]pyrene in S8zone, andTPHs in S8, S9, S12.(4) On the basis of the human health risk assessment, risk-based soil remedial targetsof the above contaminants have been suggested as follows:20mg·kg-1for As in surfacesoil,76mg·kg-1for As in underlayer soil,250mg·kg-1for V,190mg·kg-1for Cu,530mg·kg-1for Pb,5000mg·kg-1for TPH and0.3mg·kg-1for benzo[a]pyrene. In addition, byreference to U.S. EPA TCLP controlled limits, soil remedial targets based on toxicity ofthe leachate were suggested towards heavy metals contaminated soils.