Nitric oxide turnover in permeable river sediment
Nitric oxide turnover in permeable river sediment
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DOI：
10.4319/lo.2014.59.4.1310
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发表时间：
2014-07-01
影响因子：
4.5
通讯作者：
de Beer, Dirk
中科院分区：
文献类型：
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作者：
Schreiber, Frank;Stief, Peter;de Beer, Dirk
我们测量了渗透性淡水沉积物（德国威悉河）中与氧 (O-2) 和所有主要溶解的氮物质（铵、硝酸盐、亚硝酸盐和一氧化二氮 [N2O]）相关的一氧化氮 (NO) 微剖面。 NO在好氧区达到峰值浓度0.13 μmol L-1，并在好氧-缺氧过渡区被消耗。显然，NO是由氨氧化剂在好氧条件下产生的，并在微氧条件下通过反硝化作用消耗的。曝气地表水对沉积物岩心的实验渗透导致 NO 初始生成速率比稳态下 NO 净生成速率高 12 倍。该初始 NO 生成速率与净氨氧化速率处于同一范围内，表明 NO 暂时是氨氧化器的主要产物。使用 N-15 标记的化学 NO 供体 S-亚硝基-N-乙酰青霉胺 (SNAP) 进行的稳定同位素标记实验 (1) 证实反硝化作用是主要的 NO 消耗途径，其中 N2O 是其主要产物，(2) 表明反硝化作用将一个游离 NO 分子与亚硝酸盐形成的一个 NO 分子结合生成 N2O，(3) 表明 NO 抑制N2O还原。
We measured nitric oxide (NO) microprofiles in relation to oxygen (O-2) and all major dissolved N-species (ammonium, nitrate, nitrite, and nitrous oxide [N2O]) in a permeable, freshwater sediment (River Weser, Germany). NO reaches peak concentrations of 0.13 mu mol L-1 in the oxic zone and is consumed in the oxic-anoxic transition zone. Apparently, NO is produced by ammonia oxidizers under oxic conditions and consumed by denitrification under microoxic conditions. Experimental percolation of sediment cores with aerated surface water resulted in an initial rate of NO production that was 12 times higher than the net NO production rate in steady state. This initial NO production rate is in the same range as the net ammonia oxidation rate, indicating that NO is transiently the main product of ammonia oxidizers. Stable isotope labeling experiments with the N-15-labeled chemical NO donor S-nitroso-N-acetylpenicillamine (SNAP) (1) confirmed denitrification as the main NO consumption pathway, with N2O as its major product, (2) showed that denitrification combines one free NO molecule with one NO molecule formed from nitrite to produce N2O, and (3) suggested that NO inhibits N2O reduction.