Weichun Ma

Atmospheric deposition of inorganic nitrogen to the eastern China seas and its implications to marine biogeochemistry

fluxes are 0.05–0.5 and 0.2–0.6 g m −2 yr −1 , respectively, with the wet deposition accounting for 79% of the total. The total deposition of inorganic nitrogen species, including NO3 ,N H4 , HNO3 ,N Ox, and NH3, to the eastern China seas is 498 GgN yr −1 and accounts for 3.4% of the nitrogen emission by China. Deposition of NO3 and NH4 dominates. The model results agree well with available in situ measurements. The deposition of NH4 and NH3 to the East China Sea is up to 166 GgN yr −1 , which nearly equals the total input of 184 GgN yr −1 from the mainland, including riverine discharge, industrial wastewater, and domestic wastewater. Deposition of atmospheric ammonium can account for 56% of the external total input, which is 1.1–1.5 times the input from the major rivers to all the eastern China seas. Ammonium deposition to the Yellow Sea accounts for as much as 87% of the total input. The annual total nitrogen deposition can be converted to new primary biological productivity of 100–200 mmol C m −2 yr −1 ,o r 1.1–3.9% of the new productivity in the East China Sea. Our results suggest that atmospheric deposition has important impact on biological productivity in all the eastern China seas.

Spatial and Seasonal Dynamics of Ship Emissions over the Yangtze River Delta and East China Sea and Their Potential Environmental Influence

The Yangtze River Delta (YRD) port cluster is one of five major port clusters in China and is home to Shanghai port, the largest port worldwide. In this study, an automatic identification system-based model was built to estimate the ship exhaust emissions in the YRD and the East China Sea within 400 km of the coastline. In 2010, the total emissions of SO2, NOX, and PM2.5 were 3.8 × 10(5) tonnes/yr, 7.1 × 10(5) tonnes/yr, and 5.1 × 10(4) tonnes/yr, respectively. More than 60% and 85% of the ship emissions occurred within 100 km and 200 km of the coastline, respectively. Ship emissions also showed distinct seasonal variability. The emission of SO2 and NOX by ships in hot spots, such as ports and vessel traffic hubs was much higher than that on land, with maximum SO2 and NOX intensities from ships that were 36 times and 17 times greater, respectively, than the maximal land-based emissions. The potential impact of ship emissions at six hot spots on the surrounding atmospheric environment was estimated with the HYSPLIT model. Our study demonstrated that ship emissions have an important impact on both the entire YRD region and on greater East China.

Safety distance assessment of industrial toxic releases based on frequency and consequence: A case study in Shanghai, China

A case study on the safety distance assessment of a chemical industry park in Shanghai, China, is presented in this paper. Toxic releases were taken into consideration. A safety criterion based on frequency and consequence of major hazard accidents was set up for consequence analysis. The exposure limits for the accidents with the frequency of more than 10(-4), 10(-5)-10(-4) and 10(-6)-10(-5) per year were mortalities of 1% (or SLOT), 50% (SLOD) and 75% (twice of SLOD) respectively. Accidents with the frequency of less than 10(-6) per year were considered incredible and ignored in the consequence analysis. Taking the safety distance of all the hazard installations in a chemical plant into consideration, the results based on the new criterion were almost smaller than those based on LC50 or SLOD. The combination of the consequence and risk based results indicated that the hazard installations in two of the chemical plants may be dangerous to the protection targets and measurements had to be taken to reduce the risk. The case study showed that taking account of the frequency of occurrence in the consequence analysis would give more feasible safety distances for major hazard accidents and the results were more comparable to those calculated by risk assessment.

Evaluation and potential improvements of WRF/CMAQ in simulating multi-levels air pollution in megacity Shanghai, China

The accuracy of atmospheric numerical model is important for the prediction of urban air pollution. This study investigated and quantified the uncertainties of meteorological and air quality model during multi-levels air pollution periods. We simulated the air quality of megacity Shanghai, China with WRF/CMAQ (Weather Research and Forecasting model and Community Multiscale Air Quality model) at both non-pollution and heavy-pollution episodes in 2012. The weather prediction model failed to reproduce the surface temperature and wind speed in condition of high aerosol loading. The accuracy of the air quality model showed a clear dropping tendency from good air quality conditions to heavily polluted episodes. The absolute model bias increased significantly from light air pollution to heavy air pollution for SO2 (from 2 to 14%) and for PM10 (from 1 to 33%) in both urban and suburban sites, for CO in urban sites (from 8 to 48%) and for NO2 in suburban sites (from 1 to 58%). A test of applying the Urban Canopy Model scheme to the WRF model showed fairly good improvement on predicting the meteorology field, but less significant effect on the air pollutants (6% for SO2 and 19% for NO2 decease in model bias found only in urban sites). This study gave clear evidence to the sensitivities of the model performance on the air pollution levels. It is suggested to consider this impact as a source for model bias in the model assessment and make improvement in the model development in the future.

The Application of Expert System to the Screening of Atmospheric Environmental Impact from Comprehensive Road Traffic Planning in Shanghai

This paper presented the development of an expert system (ES) and its integration with GIS and mathematical models to advance a method to identify the significant atmospheric environmental impact caused by road traffic. Based on the literature reviews and consultations with experts, the paper addressed two major impact factors-photochemical smog and visibility for which ES knowledge base and reasoning had been developed. The development of GIS platform was based on the ArcObjects, and the ES was developed using ClipsActiveXControl. Finally, a case study of the screening of atmospheric environmental impact of comprehensive road traffic planning in Shanghai was presented. The case study shows that ES and its integration with GIS and mathematical models are supportive for the preliminary assessment of atmospheric environmental impact of urban traffic planning, and the component technology is an important means for system integration, which will improve the efficiency and flexibility of system development.