Nitrification and Denitrification in Lake and Estuarine Sediments Measured by the 15N Dilution Technique and Isotope Pairing
Nitrification and Denitrification in Lake and Estuarine Sediments Measured by the 15N Dilution Technique and Isotope Pairing
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DOI：
10.1128/aem.59.7.2093-2098.1993
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发表时间：
1993-07
影响因子：
4.4
通讯作者：
S. Rysgaard;N. Risgaard-Petersen;L. Nielsen;N. Revsbech
中科院分区：
文献类型：
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作者：
S. Rysgaard;N. Risgaard-Petersen;L. Nielsen;N. Revsbech
在连续流动系统中分析了在黑暗中孵化的湖泊和河口沉积物中氮化合物的转化。进水中含有15NO3-，通过对出水中N_2、NO_3~-和NH_4~+的同位素组成的测定，可以量化出以下反应：总的NO_3吸收、上覆水中基于NO_3-的反硝化、硝化、耦合硝化-反硝化和N的矿化。在湖泊和河口环境的沉积物岩心中，底栖微型植物在变暗后对NO3-和NH4+的同化时间为25~60h。在黑暗的稳态条件下，湖泊沉积物中来自上覆水的NO3-的反硝化作用占91~171molm-2 h-1，河口沉积物中的反硝化作用占131~182μμm-2 h-1，相当于两种沉积物NO3-吸收总量的100%。在早期的研究中，底栖微型植物在最初的黑暗时期对NO3的高吸收似乎被误解为异化还原为氨。底泥中的硝化-反硝化耦合作用占稳定状态下总反硝化作用的10%，而总硝化作用仅为耦合作用的两倍。
The transformation of nitrogen compounds in lake and estuarine sediments incubated in the dark was analyzed in a continuous-flowthrough system. The inflowing water contained 15NO3-, and by determination of the isotopic composition of the N2, NO3-, and NH4+ pools in the outflowing water, it was possible to quantify the following reactions: total NO3- uptake, denitrification based on NO3- from the overlying water, nitrification, coupled nitrification-denitrification, and N mineralization. In sediment cores from both lake and estuarine environments, benthic microphytes assimilated NO3- and NH4+ for a period of 25 to 60 h after darkening. Under steady-state conditions in the dark, denitrification of NO3- originating from the overlying water accounted for 91 to 171 μmol m-2 h-1 in the lake sediments and for 131 to 182 μmol m-2 h-1 in the estuarine sediments, corresponding to approximately 100% of the total NO3- uptake for both sediments. It seems that high NO3- uptake by benthic microphytes in the initial dark period may have been misinterpreted in earlier investigations as dissimilatory reduction to ammonium. The rates of coupled nitrification-denitrification within the sediments contributed to 10% of the total denitrification at steady state in the dark, and total nitrification was only twice as high as the coupled process.