Quantification of nitrogen dry and wet deposition in Fujian tobacco planting area

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• 作者：Wen Xu^a ; Wenqing Li^b ; ^{li-wqfjyc@163.com} ; Shunhui Chen^b ; Daowei Yang^a ; Yangyang Zhang^a ; Jing Xue^a ; Xuejun Liu^a ; ^{liu310@cau.edu.cn}
• 关键词：Reactive N ; Dry deposition ; Wet deposition ; Anthropogenic impact ; Tobacco field
• 刊名：Acta Ecologica Sinica
• 出版年：2016
• 出版时间：December 2016
• 年：2016
• 卷：36
• 期：6
• 页码：424-432
• 全文大小：1141 K
• 卷排序：36

文摘

In this study, the wet/bulk and dry atmospheric deposition of different inorganic nitrogen (N) species was investigated in the Fujian tobacco planting area from 2010 to 2014. Wet/bulk N deposition flux of inorganic N was monitored at five sites (Fuzhou, Shanghang, Changting, Taining, and Wuyishan) of Fujian by using precipitation gauges. While dry deposition fluxes of gaseous NH3, NO2, and HNO3 (gNH3, gNO2, and gHNO3), and particulate NH4+ and NO3− (pNH4+ and pNO3−) were estimated only at the Fuzhou site through multiplying monthly mean Nr concentrations obtained from DELTA (DEnuder for Long-Term Atmospheric sampling) system (gNH3, gHNO3, pNH4+, pNO3−) and passive samplers (gNO2) and the modeled monthly mean dry deposition velocities provided by the GEOS-Chem global chemical transport model. Annual mean NH4+-N, NO3−-N, and total inorganic N (TIN) concentrations in precipitation (rainwater and snow) were 0.21–1.05, 0.33–0.74, and 0.59–1.68 mg N L−1, respectively, and the averages over the monitoring period were 0.55, 0.49, and 1.04 mg N L− 1, respectively. Across the five monitoring sites, the average annual wet/bulk N deposition was 17.6 kg N ha−1 a−1, while that of NH4+-N and NO3−-N amounted to 9.2 and 8.4 kg N ha− 1 a− 1, respectively. Wet/bulk deposition was lowest at Changting, but no significant differences were found between the other four sites. Annual mean atmospheric concentrations of gNH3, gNO2, gHNO3, pNH4+, and pNO3− were 1.87, 2.95, 0.45, 2.36, and 1.23 μg N m−3, respectively. Gaseous NH3 concentrations were highest in summer and lowest in winter. In contrast, seasonal fluctuations in other measured Nr species (e.g., gNO2) were not as large as those of gNH3.The annual mean total dry deposition was estimated to be 9.6 kg N ha−1 a−1, and those of the individual species, gNH3, gNO2, gHNO3, pNH4+, and pNO3− were estimated to be 4.1, 2.2, 2.0, 0.8, and 0.4 kg N ha−1 a−1, respectively. Based on the similarities in wet deposition, if we assume a similar level of dry deposition at all the sites, the total (dry and wet) N deposition was 27.2 kg N ha−1 a−1 on average, which twice the critical load (10–15 kg N ha−1 a−1) for forest ecosystems, suggesting a risk of “N saturation” in the local natural environment.