Nitrogen substrate-dependent nitrous oxide cycling in salt marsh sediments
Nitrogen substrate-dependent nitrous oxide cycling in salt marsh sediments
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DOI：
10.1357/002224015815848820
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发表时间：
2015-05-01
影响因子：
0.5
通讯作者：
Ward, Bess B.
中科院分区：
文献类型：
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作者：
Ji, Qixing;Babbin, Andrew R.;Ward, Bess B.
一氧化二氮 (N2O) 对地球气候很重要，因为它是强辐射吸收剂和重要的臭氧消耗剂。增加海洋环境特别是沿海水域的人为氮输入导致氧化亚氮排放量增加。识别沿海水域中 N2O 产生底物的氮化合物揭示了重要的途径，并帮助我们了解环境因素对它们的控制。在这项研究中，沉积物是从马萨诸塞州法尔茅斯大西佩威塞特沼泽的长期施肥地点收集的。进行了 N-15 示踪剂孵育时间过程实验并分析了潜在的 N2O 产生和消耗率。 N2O生产的两种氮底物，铵和硝酸盐，分别对应于硝化和反硝化两种生产途径。当存在可测量的硝酸盐时，尽管环境铵浓度较高，反硝化作用仍是主要的 N2O 产生途径。当硝酸盐不存在时，铵通过硝化作用和耦合硝化-反硝化作用成为 N2O 产生的主要底物。在低氧和硝酸盐条件下，净 N2O 消耗量增加。在长期试验田中，N2O 的产生和消耗率随着施氮量的增加而增加。这些结果表明，增加盐沼的人为氮输入可以通过硝化和反硝化刺激沉积物 N2O 的产生，而间歇性氧耗竭会导致 N2O 净消耗。
Nitrous oxide (N2O) is important to Earth's climate because it is a strong absorber of radiation and an important ozone depletion agent. Increasing anthropogenic nitrogen input into the marine environment, especially to coastal waters, has led to increasing N2O emissions. Identifying the nitrogen compounds that serve as substrates for N2O production in coastal waters reveals important pathways and helps us understand their control by environmental factors. In this study, sediments were collected from a long-term fertilization site in Great Sippewissett Marsh, Falmouth, Massachusetts. The N-15 tracer incubation time course experiments were conducted and analyzed for potential N2O production and consumption rates. The two nitrogen substrates of N2O production, ammonium and nitrate, correspond to the two production pathways, nitrification and denitrification, respectively. When measurable nitrate was present, despite ambient high ammonium concentrations, denitrification was the major N2O production pathway. When nitrate was absent, ammonium became the dominant substrate for N2O production, via nitrification and coupled nitrification-denitrification. Net N2O consumption was enhanced under low oxygen and nitrate conditions. N2O production and consumption rates increased with increasing levels of nitrogen fertilization in long-term experimental plots. These results indicate that increasing anthropogenic nitrogen input to salt marshes can stimulate sedimentary N2O production via both nitrification and denitrification, whereas episodic oxygen depletion results in net N2O consumption.