Biogeochemistry of nitrous oxide in Lake Kizaki, Japan, elucidated by nitrous oxide isotopomer analysis
Biogeochemistry of nitrous oxide in Lake Kizaki, Japan, elucidated by nitrous oxide isotopomer analysis
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DOI：
10.1029/2010jg001589
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发表时间：
2011-12
影响因子：
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通讯作者：
Y. Sasaki;K. Koba;M. Yamamoto;Akiko Makabe;Y. Ueno;M. Nakagawa;S. Toyoda;N. Yoshida;M. Yoh
中科院分区：
文献类型：
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作者：
Y. Sasaki;K. Koba;M. Yamamoto;Akiko Makabe;Y. Ueno;M. Nakagawa;S. Toyoda;N. Yoshida;M. Yoh
[1] 在日本木崎湖对一氧化二氮 (N2O) 的生物地球化学进行了研究，观察到水柱中 N2O 的积累。尽管在更深的缺氧区观察到更高和更低的 N2O 浓度，但 N2O 浓度分布显示好氧区的积累较弱。随着 N2O 浓度的增加，好氧区内 15N（位点偏好）N2O 的分子内分配也随之增加。好氧区新产生的N2O的位置偏好估计为33.6‰。这种高位点偏好强烈表明这种 N2O 是由羟胺氧化产生的。在缺氧区，硝酸盐（NO3−）浓度迅速下降，同时氮和氧同位素比值增加，表明存在反硝化作用。 N2O (δ15Nbulk) 的高位点偏好和氮同位素比，结合 NO3− 的同位素数据，强烈表明反硝化是主要的 N2O 来源。此外，选址偏好和 δ15Nbulk 数据表明，缺氧区域中现有的 N2O 已被强烈还原（超过 75%）为 N2。这项研究的结果证明了使用 N 化合物的同位素和同位素异构体分析来阐明完整生态系统中 N2O 复杂的生物地球化学的可行性。
[1] The biogeochemistry of nitrous oxide (N2O) was investigated in Lake Kizaki, Japan, where accumulation of N2O in the water column has been observed. The N2O concentration profile showed weak accumulation in the oxic zone, although much higher and much lower N2O concentrations were observed in the deeper oxygen-deficient zone. Intramolecular partitioning of 15N (site preference) of N2O within the oxic zone increased concomitantly with increased N2O concentration. The site preference of the newly produced N2O in the oxic zone was estimated as 33.6‰. This high site preference strongly suggests that this N2O was produced by hydroxylamine oxidation. In regions of the oxygen-deficient zone, the nitrate (NO3−) concentration decreased rapidly, concomitantly with increased nitrogen and oxygen isotope ratios, indicating denitrification. The high site preference and nitrogen isotope ratio of N2O (δ15Nbulk), combined with isotopic data of NO3−, strongly suggest denitrification as the main N2O source. Moreover, site preference and δ15Nbulk data suggest that the existing N2O in the oxygen-deficient zone was already strongly reduced (more than 75%) to N2. Results of this study demonstrate the feasibility of using isotope and isotopomer analyses of N compounds to elucidate the complex biogeochemistry of N2O in an intact ecosystem.