Impacts of Atmospheric Mercury Deposition on Human Multimedia Exposure: Projection from Observations in the Pearl River Delta Region, South China.

A preliminary projection was performed to determine human multimedia exposure to mercury (Hg) based on deposition flux observations and to identify the impacts of atmospheric Hg deposition in Pearl River Delta (PRD) region, South China. The Monte Carlo technique was used to propagate the variability throughout the projection. The regional specific probability density functions (PDFs) of the studied parameters were regressed from the provincial/national published data, except when the data were deficient. The atmospheric Hg deposition flux ranged from 43.70 to 321.19 μg/m2/year and did not significantly contribute to Hg accumulation in the regional topsoil, freshwater bodies, and most food items except fish. The consumption of fish and milk/dairy products was the major contributor to the total exposure for adults (>18 years)/6- to 12-year children and 0- to 6-year children, respectively. The projected concentrations and exposure levels were the results combining MeHg and inorganic Hg (Hg2+). Under the 30-year projection, the probability of risks caused by Hg deposition (combining Hg2+ and MeHg) was the highest for 0- to 6-year children, followed by 6- to 12-year children and adults. The ground effects driven by precipitation had a significantly greater effect relative to the mass transport effects in this region.