| As a global pollutant mercury has caused significant effects on public health. Mercury pollution has become one of the most important global environmental issues. China is the largest anthropogenic mercury emission source in the world. The main mercury pollution industries were PVC production, battery production, thermometer and sphygmomanometer production, coal combustion, non-ferrous metal smelting and so on. Numerous studies on Hg pollution have been carried out in China, most of which have focused on major industries, such as Hg mining, coal combustion, chlorin-alkali production and gold mining. However, Hg pollution arising from other industries (such as electronic waste recycling industry, petrochem industry and chemical industry) received little scientific attention.In order to study mercury pollution characteristics and assess the potencial health risk of Hg contamination to the related population, environmental samples and foodstuff samples were collected from electronic waste recycling area, petrochem area and chemical area to detect mercury content.The results are shown as follows:(1) The mean concentrations of gaseous elemental mercury in electronic waste recycling area was30.7ng/m3, but the total Hg content in soil was3.1μg/g, which exceeded national standard value. The total Hg content in rice, corn, soybean and cole exceeded mercury safety limits recommended by national standard (GB2762-2012). The elevated concentration of Hg in soil, atmosphere, dust, rice, corn and soybean in our study implicated that e-waste recycling was a major source of Hg emission.(2) With the distance from the chemical area increasing, the total Hg levels in soil and plant leaves decreased and then increased. The Hg concentration in plant leaves was in the range of123.2～567.4ng/g, which was much higher than literature. The MeHg concentration in plant leaves was higher than that in soil. The total Hg concentration in dust of windows and floor were higher than soil.(3) With the distance from the plant increasing, the total Hg and MeHg levels in soil decreased. The total Hg and MeHg levels in soil inside plant were much higher than those outside. The Hg concentration in plant leaves was in the range of543.6～876.4ng/g, which was higher than the literature. The Hg concentration in leaves in chlor-alkali plant was much higher than those in other sites. The Hg content in dust in chlor-alkali reactor was1897.4ng/g, which indicated that chlor-alkali reactor might be an important mercury source.(4) According to exposure pathways and absorption efficiencies of Hg species by human body, this study established a mercury exposure assessment model to assess total daily intakes of Hg species for both children and adults. The result greatly exceeded the MeHg dietary reference dose of230ng/(kg-day) as recommended by WHO, implying greater health risk for humans especially young children from Hg exposure around e-waste recycling facilities.(5) The daily uptake different forms of mercury in the population from petrochem area did not exceed mercury safety limits recommended by US EPA. But the high frequency fish consumption might result in an undesirable Hg exposure to residents, especially the susceptible populations(6) The daily uptake different forms of mercury in the population from chemical area did not exceed mercury safety limits recommended by US EPA. The daily uptake of different forms of mercury through fish, vegetable and rice consumption were elevated compared to other routes of exposure.(7) The total daily mercury intake for children were higher than adults. The population in electronic waste recycling area had the highest health risk than petrochem industry and chemical industry area.(8) In coal mine area, the same gradient of decreasing total Hg concentrations, including hair Hg, blood Hg and urine Hg, was found:coal miners> administrators> local resident and the total Hg levels in hair and blood of coal miners were quite low at around the same levels as the general population, but the urine Hg levels were much higher than these from administrators and local resident. The hair Hg levels in workers from electronic waste recycling area, petrochem area and chemical area were higher than safe concentration of mercury recommended by US EPA. Workers mainly exposed to inorganic Hg through long-time inhalation contaminated air and dust and other population mainly exposed to MeHg through dietary intake.In conclusion, electronic waste recycling industry, petrochem industry and chemical industry were major sources of Hg emission. More efforts are necessary to protect the related population. |
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