土壤氮氧化物排放及其对中国地区对流层光化学特性影响的数值模拟研究

MODELING OF NO_X EMISSIONS FROM SOIL AND THEIR EFFECT ON TROPOSPHERIC PHOTOCHEMISTRY IN CHINA

利用Williams的模型估计中国地区土壤氮氧化物(NOX,包括NO和NO2)的排放,并运用中尺度气象模式MM5以及光化学模式Calgrid模拟不同季节和不同人为源情况下土壤NOX排放对中国地区光化学的影响。模拟结果表明,中国地区土壤NOX排放总量为225.8 Gg N,是人为源的7%,这一比例在夏季将达到23.4%;排放量有明显季节变化和空间变化。土壤源不仅使NOX、O3、HNO3和过氧乙酰硝酸酯(PeroxyacetylNitrate,PAN)的全国平均浓度增加,还显著改变了污染物的空间分布。4种污染物全国平均浓度的最大增量分别为2.37、26.08、9.79和0.43μg m-3,增量在夏季明显高于其他季节,在各地区的增减随排放源、气象条件和光化学特性的不同而不同。随着人为NOX排放的增加,土壤源在光化学中的作用会更加显著。土壤NOX排放在对流层光化学过程中的作用不容忽视。

Based on the work of Williams et al in 1992, an inventory of soil NOx emissions for China was developed. With the aid of a mesoscale meteorological model MM5 and a photochemical model Calgfid, effects of these emissions on tropospheric photochemistry in China were investigated. For the year 2000, it was estimated that the annual soil emissions in China amounted to 225.8 Gg N, i. e. 7 % of the anthropogenic emissions. In summer, this fraction increased up to 23.4%, showing the importance of soil emissions to photochemical reactions. These emissions caused rise in average concentration of NOx, O3, HNO3 and PAN （peroxyacetyl nitrate） and variation of spatial distribution of the pollutants as well. Their maximum increments on average reached 2.37, 26.08, 9.79 and 0.43 μg m^-3, respectively, and the rising trend was much higher in summer than in any other seasons. The rise varied with the sources of emission, meteorological conditions and photochemical characteristics. With increasing anthropogenic emissions, the role of NOx emission from the soil will be more significant in tropospheric photochemistry and can not be neglected.