Environmental Geosciences, University of Basel, 4056 Basel, Switzerland; Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden.
Environmental Geosciences, University of Basel, 4056 Basel, Switzerland.
Environ Pollut. 2019 Jul;250:944-952. doi: 10.1016/j.envpol.2019.03.093. Epub 2019 Mar 24.
The Minamata Convention entered into force in 2017 with the aim to phase-out the use of mercury (Hg) in manufacturing processes such as the chlor-alkali or vinyl chloride monomer production. However, past industrial use of Hg had already resulted in extensive soil pollution, which poses a potential environmental threat. We investigated the emission of gaseous elemental mercury (Hg) from Hg polluted soils in settlement areas in the canton of Valais, Switzerland, and its impact on local air Hg concentrations. Most soil Hg was found as soil matrix-bound divalent Hg (Hg). Elemental mercury (Hg) was undetectable in soils, yet we observed substantial Hg emission (20-1392 ng m h) from 27 soil plots contaminated with Hg (0.2-390 mg Hg kg). The emissions of Hg were calculated for 1274 parcels covering an area of 8.6 km of which 12% exceeded the Swiss soil remediation threshold of 2 mg Hg kg. The annual Hg emission from this area was approximately 6 kg a, which is almost 1% of the total atmospheric Hg emissions in Switzerland based on emission inventory estimates. Our results show a higher abundance of Hg resistance genes (merA) in soil microbial communities with increasing soil Hg concentrations, indicating that biotic reduction of Hg is likely an important pathway to form volatile Hg in these soils. The total soil Hg pool in the top 20 cm of the investigated area was 4288 kg; hence, if not remediated, these contaminated soils remain a long-term source of atmospheric Hg, which is prone to long-range atmospheric transport.
《水俣公约》于 2017 年生效，旨在逐步淘汰汞（Hg）在氯碱或氯乙烯单体生产等制造工艺中的使用。然而，过去汞的工业使用已经导致了广泛的土壤污染，这构成了潜在的环境威胁。我们调查了瑞士瓦莱州定居区受汞污染土壤中气态元素汞（Hg）的排放及其对当地空气汞浓度的影响。大多数土壤汞以土壤基质结合的二价汞（Hg）形式存在。土壤中未检测到元素汞（Hg），但我们观察到大量汞排放（20-1392ngm h）来自 27 个受汞污染的土壤（0.2-390mg Hg kg）。根据土壤修复阈值 2mg Hg kg，对覆盖 8.6km 的 1274 个地块的汞排放量进行了计算，其中 12%超过了瑞士的土壤修复阈值。该地区的年汞排放量约为 6kg a，这几乎占瑞士基于排放清单估算的大气汞总排放量的 1%。我们的研究结果表明，随着土壤汞浓度的增加，土壤微生物群落中汞抗性基因（merA）的丰度更高，这表明生物还原汞可能是这些土壤中形成挥发性汞的重要途径。调查区域 20cm 表层土壤中总汞库为 4288kg；因此，如果不进行修复，这些受污染的土壤仍将是大气汞的长期来源，易发生长距离大气传输。
