Zhu Xiao, Wang Jie-Fei, Shen Jian-Lin, Xiao Run-Lin, Wang Juan, Wu Jin-Shui, Li Yong
Key Laboratory of Agro-ecological Processes in Subtropical Regions, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
Changsha Research Station for Agricultural & Environmental Monitoring, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China.
Huan Jing Ke Xue. 2018 Jun 8;39(6):2557-2565. doi: 10.13227/j.hjkx.201710127.
Atmospheric emissions of reactive nitrogen (N) species are at high levels and have caused high N deposition in China in recent years. In this study, atmospheric wet-only and bulk N depositions were monitored simultaneously in a two-year study at an agricultural site (HN) and a forest site (XS) in the Jinjing River catchment in Changsha County, Hunan Province in subtropical China. The differences in concentration and deposition of NH-N, NO-N, DON, and TN between wet-only and bulk N depositions were compared, and the correlation between wet-only and bulk N depositions was analyzed, with the aim of estimating atmospheric wet N deposition based on bulk N deposition. During the monitoring period, NH-N was the dominant species in both wet-only and bulk deposition at the sampling sites. The average values of total N (TN) depositions for wet-only and bulk depositions at HN were 26.2 and 28.9 kg·(hm·a), respectively. The proportions of NH-N, NO-N, and DON in TN in wet-only deposition were 49.7%, 31.3%, and 19.0%, respectively, while the proportions in the bulk deposition were 48.7%, 31.6%, and 19.7%, respectively. The average values of TN depositions for wet-only and bulk depositions at XS were 23.6 and 27.8 kg·(hm·a), respectively. The proportions of NH-N, NO-N, and DON in TN in wet-only deposition were 53.9%, 34.78%, and 11.4%, respectively, while they were 49.6%, 31.6%, and 18.9%, respectively, for bulk deposition. The concentrations of N species in wet-only and bulk depositions were significantly and negatively correlated with precipitation, while the amount of N deposition was significantly and positively correlated with precipitation. The concentrations of N species in wet-only deposition had a significant linear correlation with those in the bulk deposition at the two sites (>0.82). According to the regression equation for wet-only and bulk N deposition at the monitoring sites, the proportions of NH-N, NO-N, and TN in wet-only to bulk deposition were 0.875, 0.774, and 0.852, respectively, at HN and 0.859, 0.783, and 0.819, respectively, at XS. These values were mainly related to the amount of wet-only N deposition and the pollution level of atmospheric particulate N species at the monitoring sites. In the subtropical region of China, atmospheric wet N deposition can be overestimated by 10% to 18% when the atmospheric bulk N deposition is used to replace the wet N deposition. Based on the regression equation between atmospheric bulk N deposition and wet N deposition, the atmospheric wet N deposition can be estimated well using the atmospheric bulk N deposition data.
近年来，中国活性氮（N）物种的大气排放量处于高水平，导致高氮沉降。在本研究中，于中国亚热带地区湖南省长沙县金井河流域的一个农业站点（HN）和一个森林站点（XS）进行了为期两年的研究，同时监测了大气湿沉降和总沉降中的氮。比较了湿沉降和总沉降中NH-N、NO-N、DON和TN的浓度及沉降差异，并分析了湿沉降和总沉降之间的相关性，旨在基于总氮沉降估算大气湿氮沉降。在监测期间，NH-N是采样点湿沉降和总沉降中的主要物种。HN站点湿沉降和总沉降中总氮（TN）沉降的平均值分别为26.2和28.9 kg·(hm·a)。湿沉降中TN里NH-N、NO-N和DON的比例分别为49.7%、31.3%和19.0%，而总沉降中的比例分别为48.7%、31.6%和19.7%。XS站点湿沉降和总沉降中TN沉降的平均值分别为23.6和27.8 kg·(hm·a)。湿沉降中TN里NH-N、NO-N和DON的比例分别为53.9%、34.78%和11.4%，而总沉降中的比例分别为49.6%、31.6%和18.9%。湿沉降和总沉降中氮物种的浓度与降水量显著负相关，而氮沉降量与降水量显著正相关。两个站点湿沉降中氮物种的浓度与总沉降中的浓度具有显著的线性相关性（>0.82）。根据监测站点湿沉降和总氮沉降的回归方程，HN站点湿沉降中NH-N、NO-N和TN与总沉降的比例分别为0.875、0.774和0.852，XS站点分别为0.859、0.783和0.819。这些值主要与监测站点的湿氮沉降量和大气颗粒氮物种的污染水平有关。在中国亚热带地区，当用大气总氮沉降代替湿氮沉降时，大气湿氮沉降可能被高估10%至18%。基于大气总氮沉降和湿氮沉降之间的回归方程，利用大气总氮沉降数据可以很好地估算大气湿氮沉降。
