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

摘要

A better understanding of the discrepancies in multi-scale inventories couldgive an insight into their approaches and limitations as well as provideindications for further improvements; international, national, andplant-by-plant data are primarily obtained to compile those inventories. Inthis study we develop a high-resolution inventory of Hg emissions at0.05°  ×  0.05° for Jiangsu, China, using a bottom-upapproach and then compare the results with available global/nationalinventories. With detailed information on individual sources and the updatedemission factors from field measurements applied, the annual Hg emissions ofanthropogenic origin in Jiangsu in 2010 are estimated at 39 105 kg, ofwhich 51, 47, and 2 % were Hg, Hg, and Hg, respectively. Thisprovincial inventory is thoroughly compared to three downscaled nationalinventories (NJU, THU, and BNU) and two global ones (AMAP/UNEP andEDGARv4.tox2). Attributed to varied methods and data sources, clearinformation gaps exist in multi-scale inventories, leading to differences inthe emission levels, speciation, and spatial distributions of atmospheric Hg.The total emissions in the provincial inventory are 28, 7, 19, 22, and70 % larger than NJU, THU, BNU, AMAP/UNEP, and EDGARv4.tox2,respectively. For major sectors, including power generation, cement, iron andsteel, and other coal combustion, the Hg contents (HgC) in coals/rawmaterials, abatement rates of air pollution control devices (APCDs) andactivity levels are identified as the crucial parameters responsible for thedifferences in estimated emissions between inventories. Regarding speciatedemissions, a larger fraction of Hg is found in the provincialinventory than national and global inventories, resulting mainly from theresults by the most recent domestic studies in which enhanced Hg weremeasured for cement and iron and steel plants. Inconsistent information onlarge power and industrial plants is the main source of differences inspatial distribution of emissions between the provincial and otherinventories, particularly in southern and northwestern Jiangsu, whereintensive coal combustion and industry are located. Quantified with MonteCarlo simulation, uncertainties in the provincial inventory are smaller thanthose of the NJU national inventory, resulting mainly from the more accurateactivity data of individual plants and the reduced uncertainties in HgC incoals/raw materials.