Assessment on mercury pollution in vegetable soil in rural Guangzhou and its ecological and human health risk

Objective To examine mercury content in vegetable soil of rural Guangzhou and to evaluate its ecological and human health risks and to provide evidences for local mercury pollution prevention and ecological environmental protection.

Methods Totally 367 soil samples were collected from vegetable fields in 58 rural villages in 7 districts across Guangzhou and mercury content in the samples was detected from 2015 to 2018. Potential ecological risk related to vegetable soil mercury was assessed using Hankanson potential risk index method. In addition, the model recommended by United States Environment Protection Agency (USEPA) was adopted to evaluate the human health risk associated with oral intake, respiratory inhalation and skin contact of the soil mercury.

Results For all soil samples, the mercury contents ranged from 0.007 4 to 4.65 mg/kg, with an average content of 0.31 mg/kg. The overall qualification rate of soil mercury content was 79.29% (291/367) and the rate varied by regions, with the lowest rate of 37.50% for the samples collected in Huangpu district. The potential ecological harm coefficients for mercury in the soil samples were from 7 to 4 650 and 86.38% of the soil samples were assessed as intensely, seriously or extremely harm to ecological environment. The non-carcinogenic hazard indices for the soil mercury contents were below 1 for both the exposed adults and children and exposures to the soil mercury were mainly through oral intake, followed by skin contact and respiratory inhalation. The non-carcinogenic hazard index for the soil mercury contents was higher for the exposed children than that for the exposed adults.

Conclusion Various degrees of soil mercury pollution exist in vegetable fields of rural Guangzhou and may impact a serious ecological risk. The non-carcinogenic hazard of the soil mercury is within an acceptable range for the exposed adults and children. The results suggest that relevant measures should be taken to prevent and control potential ecological harm caused by the soil mercury pollution.