在对我国大气氮沉降观测方法进行系统整理的基础上,以珠三角为例对长期氮沉降观测的结果进行了详细的时空分析.结果显示,大气氮沉降通量从东南沿海到西北内陆递减,且遭受人类活动影响较大的生态系统具有高沉降负荷的倾向.森林生态系统湿沉降通量的观测值变化范围为18~38kgN/(hm2·a);农田生态系统中湿沉降通量的变化范围为6~78kgN/(hm2·a),混合沉降通量为15~133kgN/(hm2·a),干沉降通量为54~83kgN/(hm2·a);而在城市生态系统中混合沉降通量可达101kgN/(hm2·a).在人口密集的珠三角地区,氮沉降通量与NH4+-N/NO3--N值近年来均呈下降趋势,这主要与珠三角产业结构调整以及城市发展带来的巨大能耗有关.整体而言,我国氮沉降观测方法日渐趋于多样化,且观测的准确度不断提高,但偏远地区观测站点仍较为匮乏.对氮沉降的研究多集中于湿沉降和混合沉降,而针对干沉降的研究仍较为不足.%The present study reviewed the methodologies currently applied to atmospheric nitrogen deposition observation in China, as well as analyzed the long-term trend of the nitrogen deposition observed in the Pearl River Delta (PRD) region, South China. The atmospheric nitrogen deposition flux decreased from the southeast coast to the northwest inland, and the ecosystems influencing by more human activities tended to be of higher deposition load. The wet deposition fluxes were in the range of 18~38kgN/(hm2·a) and 6~78kgN/(hm2·a) for forest ecosystem and cropland ecosystem, respectively. More specifically in cropland, the fluxes of bulk deposition and dry deposition were respectively 15~133kgN/(hm2·a) and 54~83kgN/(hm2·a). And the bulk deposition flux in the urban ecosystem had achieved to 101kgN/(hm2·a). In the PRD region, the deposition fluxes of total nitrogen and the ratio of NH4+-N/NO3--N were declining in the past years. This could be explained by the industrial structure adjustment and the huge energy consumption accompanied with urban development. In general, the measurements for nitrogen deposition observation in China are becoming more and more diversified, and the results are also becoming more convincing. However, the observation is very scarce in the remote areas and wet deposition and bulk deposition, while the study of dry deposition is still insufficient.
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