大连市区大气氮湿沉降研究

Program on the nitrogen concentrations in rain water in Dalian city

雨水的主要成分是水并含有低浓度的含氮化合物,降落在春夏秋3季的雨水对植物生长有一定的影响。雨水除满足植物生理生态需水外,也为植物提供了一定的氮营养。确定雨水中的含氮量多少时空分布状况对植物生长状况的影响不论从环境科学还是植物生长科学都有一定的意义。通过2009—2010年对位于我国辽东半岛最南端的大连市区的雨水连续收集,利用流动分析仪测定雨水中的活性氮化合物含量及变化趋势,可能对生态环境有一定的影响。结果表明：两年的降雨次数分别为34和51次,降雨量分别为687.55和630.22 mm,介于常年年平均降雨量（550~950 mm）的范围内。雨水的总含氮量分别为22.94和41.65 kg.hm-2,总无机含氮量分别为17.67和18.67 kg.hm-2,其中,前1年铵态氮和硝态氮的通量分别为7.99和9.68 kg.hm-2;后1年铵态氮和硝态氮的通量分别为7.72和10.95 kg.hm-2,降雨量大的7和8月份氮沉降通量大,氮沉降通量的变化趋势与降雨量一致。降氮强度各月分布不均,2年的月平均值分别为0.42和0.55 mg.L-1.h-1,总氮的沉降强度按季节排序为冬季〉秋季〉春季〉夏季。随降雨沉降的活性氮化合物可以作为植物生长的氮源,每年平均沉降的总氮相当于使用69.15 kg.hm-2的尿素。一般来说雨水中的无机氮化合物能被植物直接利用,含量多少对不同生态系统产生不同的影响;在农田生态系统有利于作物和杂草的生长,在江河湖海边缘有利于植被的生长,产生富营养化。大连市区2年的月平均降氮质量浓度为4.90 mg.L-1,已远远超出富营养水体中氮质量浓度的阈值,周边水体存在富营养化的隐患。

The rainfall water contains mainly water and low concentration of nitrogen compounds which have certain impacts on plants growing in spring, summer and autumn. Besides rain water demands satisfy plant growing in physiology and ecology water, it also provide for nitrogen nutrition in plant. Regardless of environmental science or plant growing science, it has a certain significance to determine the nitrogen content in the rain water how to affect plant growing at the distributions of spaces and times. Content of atmospheric active nitrogen in precipitation rain was examined in the city of Dalian, the most southern tip of Liaodong Peninsula, China. The wet atmospheric deposition samples were collected continuously in rainy days in the years between in 2009 and 2010, which were measured by rain gauge and analyzed by Continuous Flow Analytical System .It was found that among the two years the rainfall times were 34 and 51 while the precipitation values were 687.55 and 630.22 mm, respectively, which were the range on mean annual precipitation（550-950 mm） in normal years .The total nitrogen contents were 22.94 and 41.65 kg-hm2 in the years of 2009 and 2010 while the total inorganic nitrogen contents were 17.67 and 18.67 kg·hm2, for the previous year ,the amount of ammonia nitrogen and nitrate nitrogen were 7.99 and 9.68 kg·hm-2 ,for the after year ,they were 7.72 and 10.95 kg·hm2. The results showed that the positive correlation of the concentrations of ammonia nitrogen and nitrate nitrogen with the rainfall amount were quite explicit. The nitrogen intensity was different in some months. It in the mean months was 0.42 and 0.55 mg·L-1·h-1 in rain water in the two years, respectively. The order to total nitrogen intensity was： winter〉 autumn 〉 spring 〉summer in the seasons The flux of total nitrogen at mean in annual was equal to 69.15 kg·hm2 usage of CO（NH）2, which was a considerable amount of nitrogen fertilizers. Some inorganic nitrogen compounds can be utilized for plant growing. However, in different ecological systems, they have different influences. They are helpful for crop production on farmland system while they would lead to eutrophication which were harmful to the environment in the edge of rivers and lakes. The monthly average nitrogen concentration in the city of Dalian both in the two years was 4.90 mg·L-1 which had far beyond the threshold of the nitrogen concentration in the eutrophic water body, the surrounding water body has the risk of eutrophication.