Mixing of Asian mineral dust with anthropogenic pollutants over East Asia: A model case study of a super-duststorm in March 2010
- ISSN: 16807316
- DOI: 10.5194/acp-12-7591-2012
Mixing of Asian mineral dust with anthropogenic pollutants allows\npollutants (e.g. sulfate and nitrate) to be transported over longer\ndistances (e.g. to the northern Pacific, even to North America) along\nwith dust particles. This mixing therefore affects the atmospheric and\noceanic environment at local, regional and even continental scales. In\nthis study, we used a three-dimensional regional chemical transport\nmodel (Nested Air Quality Predicting Modeling System, NAQPMS) to examine\nthe degree of mixing between Asian mineral dust and anthropogenic\npollutants in a super-duststorm event during 19-22 March 2010.\nInfluences of the mixing processes on regional atmospheric environmental\nand oceanic biogeochemical cycles were also investigated. A comparison\nwith measurements showed that the model reproduced well the trajectory\nof long-range dust transport, the vertical dust profile, and the\nchemical evolution of dust particles. We found that along-path mixing\nprocesses during the long-range transport of Asian dust led to\nincreasingly polluted particles. As a result, similar to 60% of the\nsulfate and 70-95% of the nitrate in the downwind regions was derived\nfrom active mixing processes of minerals with pollutants sourced from\nthe North China Plain and enhanced by transport over South China. This\nmixing had a significant impact on the regional-scale atmospheric\ncomposition and oceanic biogeochemical cycle. Surface HNO3, SO2 and O-3\nwere decreased by up to 90%, 40% and 30 %, respectively, due to the\nheterogeneous reactions on dust particles. Fe solubility rose from\nsimilar to 0.5% in the Gobi region to similar to 3-5% in the\nnorthwestern Pacific, resulting from oxidization of SO2 on dust\nparticles. Total Fe(II) deposition in the ocean region of East Asia\nreached 327 tons during the 4-day dust event, and created a calculated\nprimary productivity of similar to 520 mg Cm-2 d(-1) in the Kuril\nIslands, which can support almost 100% of the observed mean marine\nprimary productivity in spring in this region (526 mg Cm-2 d(-1)).