Seasonal cycles of water-soluble organic nitrogen aerosols in a deciduous broadleaf forest in northern Japan
Seasonal cycles of water-soluble organic nitrogen aerosols in a deciduous broadleaf forest in northern Japan
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DOI：
10.1002/2013jd020713
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发表时间：
2014-02-16
影响因子：
4.4
通讯作者：
Kawamura, Kimitaka
中科院分区：
文献类型：
--
作者：
Miyazaki, Yuzo;Fu, PingQing;Kawamura, Kimitaka
研究了近30个月来落叶林冠层气溶胶水溶性有机氮（WSON）浓度的季节变化，以寻找其可能的来源。总悬浮颗粒物中WSON浓度（平均157 +/- 127 ng N m(-3)）和WSON/水溶性总氮质量分数（平均20 +/- 11%）表现出明显的季节循环，初夏达到最大值。夏季WSON质量主要分布在细模范围（D-p < 1.9 μ m）。WSON与-蒎烯和异戊二烯的氧化产物呈正相关，且大小分布相似，表明生物烃前体次生形成可能是夏季WSON的来源。秋季WSON的主要来源为粗粒组分（D-p > 1.9 μ m），与糖类化合物的大小分布相似，表明秋季WSON的主要来源与初级生物排放有关。WSON浓度的垂直差异表明，相对于森林地面，水溶性有机气溶胶在冠层以下富含氮。初夏WSON浓度随气溶胶中氢离子浓度的增加而增加，表明与森林外人为源相关的气溶胶酸度可能在该季节WSON的形成中起重要作用。该研究表明，在特定季节，林冠层内的多种WSON来源可能占主导地位，为森林环境中WSON的形成过程提供了见解。
The seasonal variations in aerosol water-soluble organic nitrogen (WSON) concentrations measured in a deciduous forest canopy over an approximately 30month period were investigated for possible sources in the forest. The WSON concentrations (average 157 +/- 127 ng N m(-3)) and WSON/water-soluble total nitrogen mass fractions (average 20 +/- 11%) in the total suspended particulate matter exhibited a clear seasonal cycle with maxima in early summer. The WSON mass was found to reside mostly in the fine-mode size range (D-p < 1.9 mu m) during the summer months. WSON was positively correlated with oxidation products of -pinene and isoprene with similar size distributions, suggesting that secondary formation from biogenic hydrocarbon precursors is a plausible source for WSON in summer. In contrast, the majority of WSON in autumn was associated with coarse fraction (D-p > 1.9 mu m), which was similar to the size distributions of sugar compounds, indicating that the major WSON sources in autumn are associated with primary biological emissions. The vertical differences in WSON concentrations suggest that the water-soluble organic aerosol is enriched with nitrogen below the canopy level relative to the forest floor. The WSON concentration increased with enhanced hydrogen ion concentrations in aerosol in the early summer, indicating that aerosol acidity associated with anthropogenic sources outside the forest likely plays an important role in the formation of WSON in that season. The study suggests that multiple sources of WSON within the forest canopy may dominate over others in specific seasons, providing insights into WSON formation processes in forest environments.