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Risk Assessment for a Heavy Metal Contaminated Site in Shanghai
 
  • 2015-09-06 14:29

A new commercial district will be developed at the site in Shanghai. Environmental investigation and human health risk assessment were required to be conducted at the site by a qualified organization according to national and local regulations. Greenment was entrusted to conduct the preliminary investigation and detailed investigation in August and November 2012, respectively. The investigation results indicated that the concentrations of antimony, trivalent chromium, hexavalent chromium, copper, nickel, lead and arsenic in the soil in some areas of the site were higher than screening values. In early 2013, Greenment was entrusted by the owner to conduct a human health risk assessment to determine the contaminants of concern in soil, to systemically evaluate the sensitive receptors and exposure characteristics at the site, to quantitatively estimate the risks to sensitive receptors from exposure to soil contamination at the site, and to develop the risk-based target values for soil remediation.

Ø  Assessment protocol:“Technical Guidelines for Risk Assessment of Contaminated Sites” (HJ25.3-2014);

Ø  Assessment procedure:hazards identification, exposure assessment, toxicity assessment, risk characterization and calculation of risk control values;

Ø   Target level of carcinogenic risk for a single contaminant: 10-5;

Ø Target level of non-carcinogenic hazards for a single contaminant: 1.

Potential contaminants of concern in soil were first screened based on the results of site investigation. Sensitive receptors included commercial workers, construction workers and local residents. Primary exposure pathways included oral intake, dermal contact, inhalation of indoor and outdoor particulate matters from surface soil, and inhalation of indoor and outdoor vapor from surface and subsurface soil.

Future construction workers will mainly be exposed to contaminants in surface and subsurface soil. Future commercial workers and local residents will mainly be exposed to contaminants in surface soil.

The health risks of contaminants of concern were quantitatively calculated based on the exposure models and parameters in “Technical Guidelines for Risk Assessment of Contaminated Sites” (HJ25.3-2014) and toxicological parameters in commonly used databases.

The results indicated that for hexavalent chromium, nickel, antimony and arsenic in soil in some areas of the site, the carcinogenic risks were higher than 10-5, or the non-carcinogenic hazards were higher than 1. The calculated target values for hexavalent chromium, nickel, antimony, lead and arsenic in soil were 17.7mg/kg, 418mg/kg, 47.4mg/kg, 800mg/kg and 20mg/kg, respectively.

                                                      

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