THE COUPLING OF NITRIFICATION AND DENITRIFICATION IN 2 ESTUARINE SEDIMENTS
THE COUPLING OF NITRIFICATION AND DENITRIFICATION IN 2 ESTUARINE SEDIMENTS
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DOI：
10.4319/lo.1984.29.3.0609
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发表时间：
1984-01-01
影响因子：
4.5
通讯作者：
KEMP, WM
中科院分区：
文献类型：
--
作者：
JENKINS, MC;KEMP, WM
通过15 N同位素示踪技术，于4月和8月在Patuxent Rivr河口的两个站点测量了河口沉积物[马里兰州]中的硝化和反硝化作用。在春季实验期间，根据15 NH 4+修正后标记N2的演变，直接证明了这两个过程的密切耦合：在48小时的孵育过程中，> 99%的被氧化为15 NO3-的15 NH 4+随后被还原为15 N-标记的N2，这表明这两个反应彼此非常接近地发生。这种耦合硝化反硝化减少了2个数量级的夏季，即使反硝化能力（N2生产从NO3富集）保持类似于春季水平。这种急剧的季节性硝化作用模式与细菌相对丰度的测量结果相吻合。间接证据表明，低氧化还原条件（和减少O2浓度）作为夏季硝化作用降低的可能原因。环境速率的硝化反硝化推断从15 N实验在这些沉积物。估计春季速率约为77-89 μ molN. cntdot。m-2.cntdot. h-1是类似于以前报道的denitification支持NO3-扩散从上覆水到沿海沉积物的值。
Nitrification and denitrification in estuarine sediments [Maryland] were measured by 15N isotopic tracer techniques at 2 stations in the Patuxent Rivr estuary for April and Aug. A close coupling of the 2 processes was demonstrated directly from the evolution of labeled N2 following 15NH4+ amendments during spring experiments: > 99% of the added 15NH4+ which was oxidized to 15NO3- was subsequently reduced to 15N-labeled N2 during 48-h incubations, suggesting that the 2 reactions were occuring in close proximity to one another. This coupled nitrification-denitrification was decreased by 2 orders of magnitude in the summer, even though the capacity for denitrification (N2 production from NO3- enrichment) remained similar to spring levels. This pattern of sharply seasonal nitrification was corroborated with measurments of bacterial relative abundance. Indirect evidence suggests low redox conditions (and reduced O2 concentrations) as the possible cause of decreased summertime nitrification. Ambient rates of nitrification-denitrification were inferred from 15N experiments in these sediments. Estimated springtime rates of about 77-89 .mu.mol N .cntdot. m-2 .cntdot. h-1 are similar to previously reported values for denitification supported by NO3- diffusion from overlying water to coastal sediments.