广州东北郊大气氮湿沉降动态及其与酸雨的关系

摘要

The increasing of atmospheric nitrogen deposition has seriously imperiled ecosystems, and has become a major issue of global environment. But it is not paid enough attention to the research on atmospheric nitrogen deposition in China, and the current basic data acquisition is very inadequate. For gaining the basic data of wet atmospheric nitrogen deposition, and for the deep research on the effects of atmospheric nitrogen deposition on ecosystems, the authors set up monitoring point of wet atmospheric nitrogen deposition to collect rainwater since April, 2011, and analyzed the concentrations of total nitrogen and various nitrogen forms. Through one year monitoring and analysis (from April, 2011 to March, 2012), results showed that, (1) the atmospheric nitrogen deposition at the monitoring point was 2 384.66 mg·m-2·a-1(about 23.85 kg·hm-2·a-1). The ammonium nitrogen deposition was evidently more than the nitrate nitrogen, indicating that the ammonium nitrogen was the main form of the total nitrogen deposition in the area of the monitoring point. (2) There were extremely and positively significant correlation between the wet depositions of various nitrogen forms and rainfall, the more rainfall in the month, the more proportion of nitrogen deposition in the month to the total nitrogen deposition in the year, appearing the remark seasonal variation, more deposition in spring and summer, and less deposition in autumn and winter. And (3) the pH values of rainfall was negatively and significantly related to nitrogen deposition, the higher nitrogen deposition, the lower pH values in rainwater, implying that nitrogen deposition was one of the major factors to cause acid rain.%　　大气氮沉降的增加对生态系统造成了严重的影响，已成为重大的全球性环境问题.然而，大气氮沉降研究在我国尚未引起足够的重视，现有基础数据采集非常不足.为了采集大气氮湿沉降的基础数据，为今后深入开展氮沉降对生态系统有关方面的影响提供依据，作者于2011年4月开始，在广州东北郊设置大气氮湿沉降监测点，收集雨水，并分析雨水中总氮的和各种形态氮的质量浓度.经过1年(2011年4月至2012年3月)的监测和分析，结果表明，(1)该监测点的年总氮沉降量为2384.66 mg·m-2·a-1(约为23.85 kg·hm-2·a-1)，其中，铵态氮的沉降量明显高于硝态氮，铵态氮是该监测点所在区域氮沉降的主要形式.(2)各种形态氮的湿沉降量与降雨量呈极显著正相关关系，降雨量越大的月份，该月份的氮沉降量占年度总沉降量的比例也越大，呈现出明显的季节性变化规律，春、夏季高，秋、冬季低.(3)降雨的pH值与氮沉降呈显著负相关，氮沉降量越高，雨水的pH值越低，意味着氮沉降是产生酸雨的主要因素之一.