Biogeochemistry of nitrous oxide in groundwater in a forested ecosystem elucidated by nitrous oxide isotopomer measurements
Biogeochemistry of nitrous oxide in groundwater in a forested ecosystem elucidated by nitrous oxide isotopomer measurements
复制标题
DOI：
10.1016/j.gca.2009.03.022
复制
发表时间：
2009-06-01
影响因子：
5
通讯作者：
Nakajima, T.
中科院分区：
文献类型：
--
作者：
Koba, K.;Osaka, K.;Nakajima, T.
土壤中产生和消耗NO的微生物过程的生物和物理控制非常复杂。N_2O的同位素比值（（NNO）-N-14-N-15-O-16、（NNO）-N-15-N-14-O-16和（NNO）-N-14-N-14-O-18相对于（NNO）-N-14-N-14-O-16的丰度）很有希望用于阐明完整生态系统中N_2O的生物化学作用。站点偏好，中心氮原子减去末端氮原子的氮同位素比，是有用的区分N2 O通过羟胺氧化和N2 O通过亚硝酸盐还原。我们应用这种同位素分析在温带针叶林生态系统的地下水系统。在这个位置以前的研究结果表明，地下水中的N2 O浓度变化很大，根据地下水化学，即NO3-，DOC和DO，虽然分配的N2 O生产硝化或反硝化作用是模糊的。我们的NO3-和N2 O的同位素分析（δ N-15和δ O-18）表明，反硝化作用是N2 O的主要生产过程，但由于N2 O的生产和消费过程中同位素分馏的变化很大，因此从δ N-15和δ O-18分析中得不到明确的信息。然而，N2 O的网站偏好和差异在三角洲N-15之间的NO3-和N2 O表明，硝化有助于总N2 O的生产和大多数测量N2 O已受到进一步N2 O还原为N-2。同位素和同位素异构体数据得出的N2 O地球化学的含义完全不同于那些来自传统的浓度数据的DO，NO3-，和N2 O。这种差异强调了重新考虑我们对缺氧-缺氧界面中氮循环的理解的必要性。(C)2009爱思唯尔有限公司保留所有权利。
The biological and physical controls on microbial processes that produce and consume NO in soils are highly complex. Isotoporner ratios of N2O, with abundance of (NNO)-N-14-N-15-O-16, (NNO)-N-15-N-14-O-16, and (NNO)-N-14-N-14-O-18 relative to (NNO)-N-14-N-14-O-16, are promising for elucidation of N2O biogeochernistry in an intact ecosystem. Site preference, the nitrogen isotope ratio of the central nitrogen atom minus that of the terminal nitrogen atom, is useful to distinguish between N2O via hydroxylamine oxidation and N2O via nitrite reduction.We applied this isotopomer analysis to a groundwater system in a temperate coniferous-forested ecosystem. Results of a previous study at this location showed that the N2O concentration in groundwater varied greatly according to groundwater chemistry, i.e. NO3-, DOC, and DO, although apportionment of N2O production to nitrification or denitrification was ambiguous. Our isotopic analysis (delta N-15 and delta O-18) of NO3- and N2O implies that denitrification is the dominant production process of N2O, but definitive information is not derived fro delta N-15 and delta O-18 analysis because of large variations in isotopic fractionations during production and consumption of N2O. However, the N2O site preference and the difference in delta N-15 between NO3- and N2O indicate that nitrification contributes to total N2O production and that most measured N2O has been subjected to further N2O reduction to N-2. The implications of N2O biogeochemistry derived from isotope and isotopomer data differ entirely from those derived from conventional concentration data of DO, NO3-, and N2O. That difference underscores the need to reconsider our understanding of the N cycle in the oxic-anoxic interface. (C) 2009 Elsevier Ltd. All rights reserved.