丹江口水库淅川库区大气水溶性有机氮干沉降特征及源解析

Dry deposition characteristics and source apportionment of atmospheric watersoluble organic nitrogen in the Xichuan Reservoir area of the Danjiangkou Reservoir

为探究丹江口水库淅川库区大气干沉降中水溶性有机氮(WSON)特征及其来源,采用降水降尘自动采样器收集了2021年1-12月的大气干沉降样品,分析了其中WSON、水溶性总氮(WSTN)以及水溶性无机离子的浓度,探讨了WSON的浓度水平及其来源.结果表明,采样期间,库区大气干沉降中WSON月均浓度为0.15~1.14 mg·L^(-1),年平均WSON值为0.52 mg·L^(-1),占WSTN的31%.干沉降中WSON浓度季节差异性显著,呈现出冬季最高、春季和夏季次之,秋季最低的变化规律.WSON与二次离子(NH_(4)^(+)、SO_(4)^(2-)和NO_(3)-)、Cl^(-)、K^(+)、Mg^(2+)、Ca^(2+)呈显著相关,表明WSON可能来自二次转化、生物质燃烧和扬尘.后向轨迹分析表明,库区主要受长距离传输的影响,冬季和春季的气团主要来自西北部,夏季和秋季的气团主要来自西南部.PMF分析结果表明,干沉降中WSON主要来源于二次源、农业源、扬尘源、工业源和燃烧源,且以二次源为主,贡献率为55%.研究结果为探索库区水体氮污染控制途径提供了理论基础与数据支撑.

To explore the characteristics of water-soluble organic nitrogen(WSON)and their sources in the dry deposition samples in the Xichuan Reservoir area of the Danjiangkou Reservoir.The samples from January to December 2021 were collected using a precipitation and dust fall automatic sampler.The concentrations of water-soluble components including WSON,water-soluble total nitrogen(WSTN),and water-soluble inorganic ions were analyzed,the sources of WSON were identified.The results showed that the monthly average concentration of WSON ranged from 0.15 to 1.14 mg·L^(-1).The annual average WSON concentration was 0.52 mg·L^(-1),accounting for 31%of WSTN.Significant seasonal differences in WSON concentrations were found,with the order:winter>spring>summer>autumn.The concentrations of WSON were significantly correlated with those secondary inorganic ions(NH_(4)^(+),SO_(4)^(2-),and NO_(3)^(-)),Cl^(-),K^(+),Mg^(2+),and Ca^(2+),indicating that it might be derived from secondary conversion,biomass burning,and dust.The backward trajectory analysis showed that the reservoir area was mainly affected by long-distance transmission.The air mass in winter and spring mainly come from the northwest,whereas from the southwest in summer and autumn.The results of positive matrix factorization analysis showed that WSON in dry deposition samples mainly originated from five sources:secondary formation,agricultural,dust,industrial,and combustion sources,with the most contribution of secondary formation sources(55%).The results provided the theoretical and data support in controlling nitrogen pollution in the reservoir.