Enhancement of coupled nitrification-denitrification by benthic photosynthesis in shallow estuarine sediments
Enhancement of coupled nitrification-denitrification by benthic photosynthesis in shallow estuarine sediments
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DOI：
10.4319/lo.2001.46.1.0062
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发表时间：
2001-01-01
影响因子：
4.5
通讯作者：
Joye, SB
中科院分区：
文献类型：
--
作者：
An, S;Joye, SB
净沉积物-水界面通量的氧，二氮，溶解无机碳和氮的测定在浅，潮下河口沉积物（加尔维斯顿湾，得克萨斯州）使用原位底栖室孵化。昼夜变化的沉积物需氧量和双氮通量是由于底栖光合作用的发生。白天的反硝化速率超过夜间速率。在日间室孵育期间，观察到溶解氧浓度的微小变化。在夜间，氧浓度下降，消耗反应占主导地位的氧通量。底栖微藻产氧增强速率，硝化和反硝化之间的耦合时，铵是不受限制的，导致显着损失的氮从沉积物中作为二氮气体。采用瞬态三箱模型研究了底栖生物初级生产力对沉积物氮循环的影响。模型结果表明，在存在的底栖光合作用的硝化和反硝化速率增加，并同意与观察到的模式溶解的二氮和氧通量数据在底栖室孵化。当没有光合作用，允许在模型运行期间，硝化和反硝化速率显着下降。总之，我们的研究结果表明，反硝化估计浅河口可能被低估，如果不考虑底栖生物初级生产对反硝化的影响。
Net sediment-water interface fluxes of oxygen, dinitrogen, and dissolved inorganic carbon and nitrogen were determined in shallow, subtidal estuarine sediments (Galveston Bay, Texas) using in situ benthic chamber incubations. Diel variability in the sediment oxygen demand and in the flux of dinitrogen were attributable to the occurrence of benthic photosynthesis. Daytime denitrification rates exceeded nighttime rates. During daytime chamber incubations, small changes in dissolved oxygen concentration were observed. At night, oxygen concentrations decreased, as consumption reactions dominated the oxygen flux. Oxygen production by benthic microalgae enhanced rates of, and coupling between, nitrification and denitrification when ammonium was not limiting, resulting in significant loss of nitrogen from sediments as dinitrogen gas. A transient three box model was used to assess the effect of benthic primary production on sediment nitrogen cycling. Model results demonstrate increased rates of nitrification and denitrification in the presence of benthic photosynthesis and agree well with observed patterns of dissolved dinitrogen- and oxygen-flux data obtained during benthic chamber incubations. When no photosynthesis was permitted during the model runs, rates of nitrification and denitrification decreased significantly. Together, our results suggest that denitrification estimates for shallow estuaries could be underestimated if the influence of benthic primary production on denitrification is not considered.