Application of probabilistic risk assessment (PRA) and deterministic risk assessment (DRA) at a coking plant site were compared. By DRA, Hazard Quotient (HQ) following exposure to Naphthalene (Nap) and Incremental Life Cancer Risk (ILCR) following exposure to Benzo(a)pyrene (Bap) are 1.87 and 2.12×10-4. PRA reveals valuable information regarding the possible distribution of risk, and the outputs show that Nap HQ ranges from 6.18×10-7to 6.62 and Bap ILCR ranges from 8.67×10-10to 6.89×10-4. Risk estimates of DRA locates at the 99.59th and 99.76th percentiles in the risk outputs of PRA, indicating the DRA overestimates the risk. Sensitivity analysis was done by calculating a contribution to variance for each exposure parameter and it is found that contaminant concentration in the soil (Cs), exposure duration (ED), soil ingestion rate (IRs) are the most important parameters for risk calculations
Decontamination level and residual amount of polycyclic aromatic hydrocarbons (PAHs) were investigated by ex-situ remediation technologies including biopile, soil washing and thermal desorption in a field level. After the remediation, 16 USEPA priority PAHs were decontaminated from 99.3% to 99.9% for thermal desorption, from 17.9% to 82.1% for biopile and from-27.6% to 84.3% for soil washing. Residual PAHs amount in soils by thermal desorption was below the local soil screening level, differently from that by biopile and soil washing. Especially for high molecular weight PAHs, i.e. 5-6 rings PAHs, residual amount exceeded over the screening lever 4 to 197 times for biopile and 17 to 421 times for soil washing. Additional factors, such as cost, time, operation and maintainance etc. for remedial technology selection and contaminant bioavailability in soil matrix for remediation target values, were proposed to be paid more attention for specific contaminated sites.
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