南京北郊大气降水中水溶性无机氮和有机氮沉降特征

Deposition Characteristics of Water-soluble Inorganic Nitrogen and Organic Nitrogen in Atmospheric Precipitation in the Northern Suburbs of Nanjing

基于2019~2020年在南京北郊收集的大气降水进行降水pH、电导率和化学组分分析,研究南京北郊大气降水pH值和电导率的季节变化规律,分析了降水中水溶性无机氮(WSIN)和水溶性有机氮(WSON)的污染水平和沉降特征.结果表明,观测期间南京北郊大气降水发生酸雨(pH<5.6)的频率达到37.18%,降水酸化在秋冬季节较严重,pH值随季节表现出春季>夏季>秋季>冬季的变化趋势.降水电导率平均值为29.49μS·cm^(-1),春季出现高pH和电导率与该季节大气中含量较高的扬尘有关.降水中WSIN和WSON的季节差异较大,最高和最低NO_(3)^(-)-N和NH_(4)^(+)-N浓度分别出现在春季和夏季;WSON浓度则表现为秋季(2.63 mg·L^(-1))最高.降水中WSON与水溶性总氮(WSTN)浓度平均比值约为0.47,说明WSON对总氮研究具有重要意义.WSIN和WSON湿沉降通量的平均值分别为12.10 kg·(hm^(2)·a)^(-1)和11.13kg·(hm^(2)·a)^(-1),其中无机氮沉降量主要以NH^(+)_(4)-N为主.

Based on atmospheric precipitation collected in the northern suburbs of Nanjing from 2019 to 2020,the pH,conductivity,and chemical components of precipitation were analyzed.The seasonal variation in pH and conductivity of atmospheric precipitation in the northern suburbs of Nanjing were studied.The pollution levels and deposition characteristics of water-soluble inorganic nitrogen(WSIN)and organic nitrogen(WSON)in precipitation were also analyzed.The frequency of acid rain(pH<5.6)in atmospheric precipitation in the northern suburbs of Nanjing reached 37.18%during the observation period.Precipitation acidification was more serious in autumn and winter,and the pH value showed a variation trend of spring>summer>autumn>winter.The average conductivity of precipitation was 29.49μS·cm-1;high pH and conductivity in spring were related to the high dust content in the atmosphere.The seasonal difference between WSIN and WSON in precipitation was significant.The highest and lowest concentrations of NO_(3)^(-)-N and NH^(+)_(4)-N appeared in spring and summer,respectively.The concentration of WSON was the highest in autumn(2.63 mg·L^(-1)).The average concentration ratio of WSON to water-soluble total nitrogen(WSTN)in precipitation was approximately 0.47,indicating that WSON played an important role in the study of total nitrogen.The average wet deposition fluxes of WSIN and WSON were 12.10 kg·(hm^(2)·a)^(-1) and 11.13 kg·(hm^(2)·a)^(-1),respectively,in which the inorganic nitrogen deposition was mainly NH^(+)_(4)-N.