Mercury pollution investigation in predominant plants surrounding Shenzhen Qingshuihe municipal solid waste incineration plant

In order to investigate the effects of mercury emission from municipal solid waste incineration (MSWI) on the surrounding plants and soils, the mercury concentrations were examined in the plant samples including leaves and stems and the soil samples around Shenzhen Qingshuihe MSWI Plant. Results show that, these plants are significantly polluted by mercury, the mercury concentrations of the plant leaves are 0.030 9-0.246 7 mg x kg(-1), with the mean value 0.094 8 mg x kg(-1), among the local prominent plants, the mercury concentrations in the leaves are in the order of: Acacia confuse > Litsea rotundifolia > Acacia mangium > Acacia auriculaeformis > Schima superb > Ilex asprella. The mercury concentrations of the plant stems are 0.007 4-0.119 6 mg x kg(-1), with the mean value 0.041 7 mg x kg(-1). For the same plant, the mercury concentration in its leaf correlates positively with that in its stem, but presents little correlation with that in the soil where it grows. Under the direction of the dominant wind, the concentration of smoke diffusion is often influenced by the distance from the stack and the difference of terrain. The mercury concentrations of the plant leaves and stems vary almost in accordance with spatial heterogeneity patterns of smoke diffusion. These results demonstrate that the interaction of the smoke and plant leaves play the leading role in the mercury exchange between plants and environment.