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A high-resolution regional emission inventory of atmospheric mercury and its comparison with multi-scale inventories: a case study of Jiangsu, China

A better understanding of the discrepancies in multi-scale inventories could give an insight on their approaches and limitations, and provide indications for further improvements; international, national and plant-by-plant data sources are primarily obtained to compile those inventories. In this study we develop a high-resolution inventory of Hg emissions at 0.05° × 0.05° for Jiangsu China using a bottom-up approach and then compare the results with available global/national inventories. With detailed information on individual sources and the updated emission factors from field measurements incorporated, the annual Hg emissions of anthropogenic origin in Jiangsu 2010 are estimated at 39 105 kg, of which 51 %, 47 % and 2 % were released as Hg0, Hg2+, and HgP, respectively. This provincial inventory is thoroughly compared to the downscaled results from three national inventories (NJU, THU and BNU) and two global inventories (AMAP/UNEP and EDGARv4.tox2). Attributed to varied methods and data sources, clear information gaps exist in multi-scale inventories, leading to differences in the emission levels, speciation and spatial distributions of atmospheric Hg. The total emissions in the provincial inventory are the largest, i.e., 28 %, 7 %, 19 %, 22 %, and 70 % higher than NJU, THU, BNU, AMAP/UNEP, and EDGARv4.tox2, respectively. For major sectors including power generation, cement, iron & steel and other coal combustion, the Hg contents (HgC) in coals/raw materials, abatement rates of air pollution control devices (APCD) and activity levels are identified as the crucial parameters responsible for the differences in estimated emissions between inventories. Regarding speciated emissions, larger fraction of Hg2+ is found in the provincial inventory than national and global inventories, resulting mainly from the results by the most recent domestic studies in which enhanced Hg2+ were measured for cement and iron & steel plants. Inconsistent information of big power and industrial plants is the main source of differences in spatial distribution of emissions between the provincial and other inventories, particularly in southern and northwestern Jiangsu where intensive coal combustion and industry are located. Quantified with Monte-Carlo simulation, uncertainties of provincial Hg emissions are smaller than those of NJU national inventory, resulting mainly from the more accurate activity data of individual plants and the reduced uncertainties of HgC in coals/raw materials.


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Copyright 南京大学赵瑜教授研究组