珠江口无机氮湿沉降规律及大气输送的研究

针对2007年3～11月广东中山市横门站的降水资料,分析了珠江口氮湿沉降特征及其来源.结果显示:研究期间横门降水中NH+4-N和NO-3-N的降雨量加权平均浓度分别为0.62和0.41mg·L-1;其季节变化规律表现为秋季最高,其次是春季,夏季最低.降水NH+4-N和NO-3-N的浓度呈显著正相关,与降水pH值呈负相关.利用气团轨迹后推以及天气形势得出,横门陆地性降水氮浓度最高,海洋性降水氮沉降通量最高.云下气团分类结果表明,海洋性NE类气团对横门无机氮湿沉降的输送负荷最大.

Wet deposition of inorganic nitrogen and atmospheric transport at the estuary of the Pearl River

Precipitation data from March to November 2007 obtained at the Hengmen station, Guangdong, were analyzed to study the origin and characteristics of inorganic nitrogen deposition at the estuary of the Pearl River. The results show that the weighted averages of rainfall ammonium and nitrate concentrations for this period were 0.62 and 0.41 mg·L-1, respectively. Their concentrations have prominent seasonal variations with highest values in autumn, followed by a second maximum in spring, and lowest values in summer. The nitrate concentration during rainfall is positively correlated to that of ammonium, and both concentrations are negativelycorrelated with rainfall pH. According to the analysis of backward trajectory and synoptic weather patterns, the continental precipitation has the highest amount of NO-3-N and NH+4-N, while the deposition flux of NO-3-N and NH+4-N is highest for oceanic precipitation. Further analyses using backward trajectory were conducted to characterize air masses below clouds for both oceanic and continental precipitation events, and the results show that air masses from NE in the oceanic precipitation has the largest contribution to the deposition flux of inorganic nitrogen.