RESUMO
Risk assessment is a critical part of risk management for contaminated sites. Howeverï¼ in the specific management practice of As-contaminated sitesï¼ it is difficult to obtain realistic health risks for contaminated sites based on the total amount of pollutants and determined values of the modelï¼ thus preventing the control requirements of later remediation to be met. An increasing number of studies have recently been conducting risk assessments by considering bioavailabilityï¼ modification parametersï¼ and combined probabilistic models. To improve the accuracy of risk assessment resultsï¼ taking a large As-contaminated site as a caseï¼ 432 sampling sites were set up and collected at different depths to analyze the level and distribution characteristics of As pollutionï¼ and probabilistic risk assessment was conducted with the modification of model parameters through literature research and Monte Carlo simulation. Thenï¼ the impact of traditional methods and probabilistic methods on health risk assessment was explored in comparison. The results indicated that ωï¼Asï¼ in the top soil of the study area ranged from 2.70-97.0 mg·kg-1ï¼ with a spatial variation coefficient of 0.61 and weaker spatial continuity. The carcinogenic risk and hazard index obtained by the traditional risk assessment method were 2.12E-4 and 8.36ï¼ respectivelyï¼ which obviously overestimated the actual risk level and were not conductive to the refined management of As-contaminated sites. Combined with modification of model parameters and probabilistic risk assessmentï¼ the non-carcinogenic risk for adults and children was found to be at an acceptable levelï¼ and the carcinogenic risk was reduced by nearly an order of magnitude compared to that in the conventional method. Considering the relative biological effectiveness ï¼RBAï¼ of Asï¼ the 95% quantile of the total carcinogenic risk was 1.24E-5ï¼ a reduction of up to 36.41% compared to the uncorrected corresponding risk value of 1.95E-5. The carcinogenic risk of soil As for adults and children in the study area exceeded acceptable risk levels 1E-6ï¼ with oral ingestion of soil being the primary route of exposure. In additionï¼ the results of the sensitivity analysis of the parameters showed that As concentrationï¼ daily oral ingestion rate of soilsï¼ and exposure duration of children had relatively larger effects for health risks. This work will provide a methodological and theoretical basis for achieving accurate risk assessment of As-contaminated sites and provide concepts for refined risk management.
