| Nitrogen deposition is an important component of acid deposition, as well as asignificant nitrogen source of the ecological system. The amounts of nitrogen emission anddeposition are large in the in the Pearl River Delta (PRD) Region with well-developedindustries.. Study on the nitrogen deposition characteristics in this region is of greatscientific value and provides significant reference for both regional acid deposition researchand ecological impact assessment of the nitrogen deposition.In this study, a methodological framework for regional nitrogen depositioncharacteristics research for the Guangdong Province was established based on theWRF/SMOKE-PRD/CMAQ modeling system, including the key methods for emissioncharacteristics research and emission inventory processing, configurating the modelingsystem and performance evaluation of the system. This framework can be applied to theanalysis of nitrogen deposition characteristics in this region, providing some insight into theregional nitrogen deposition characteristics, such as nitrogen deposition flux, chemicalcomposition, temporal variation, spatial patterns and its ecological impact.Firstly, the major emission sources of inorganic nitrogen was identified based on theimproved regional emission inventory, and the SMOKE-PRD emission inventory processingsystem was also optimized in this study. The results showed that, in2006, the stationarycombustion source, mobile source and agricultural&animal husbandry were the three majorinorganic nitrogen emission sources. Besides, significant spatial difference of nitrogenemission was found, revealing that NO_x-N was the dominant pollutant in the PRD region,while NH3-N was the major pollutant in the surrounding cities.Secondly, the nitrogen deposition modeling system and the evaluation methodologywere established. Validation of the SMOKE-PRD empssion processing system, together withthe evaluation of the meteorology, air quality and nitrogen deposition were performed. Theresults show that the SMOKE-PRD processed the emission inventory correctly, the keymeteorological factors were simulated reasonably by the WRF, the air quality characteristicssuch as annual concentration, spatial pattern and compositon of the aerosol were cpatrued by the system, as well as the nitrogen deposition characteristics.Finally, an analysis of the regional nitrogen deposition characteristics was launchedbased on the evaluated nitrogen deposition simulation. The results show that (1) spatialdifference of nitrogen deposition was obvious. In particular, the PRD region, Maoming andthe Chaozhou-Shantou region were the three major deposition areas in Guangdong province;(2) there were distinct temporal-spatial characteristics for various nitrogen components, due tosources characteristics, different chemical properties and the aerosol size distributions;(3)in the PRD region, the results showed that lower deposition flux occurred during dry seasondue to precipitation variation; As for spatial patern, the flux gradually decreased from east towest, and spreaded to the mountainous area of northern guangdong from the heaviest nitrogendeposition area around Guangzhou-Foshan junction; besides, the nitrogen dry/wet sdepositionratio was about2:1in the PRD region, and the ammonia nitrogen was the dominantcomponent. |
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