Nitrous oxide formation in the Colne estuary, England: The central role of nitrite
Nitrous oxide formation in the Colne estuary, England: The central role of nitrite
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DOI：
10.1128/aem.68.3.1240-1249.2002
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发表时间：
2002-03-01
影响因子：
4.4
通讯作者：
Rusmana, I
中科院分区：
文献类型：
--
作者：
Dong, LF;Nedwell, DB;Rusmana, I
1996 年 12 月至 1998 年 3 月，每月在英国科恩河口测量水中的硝酸盐和亚硝酸盐浓度以及沉积物-水界面上的一氧化二氮和亚硝酸盐通量。科恩河口水柱中的 N2O 浓度相对于空气处于过饱和状态，表明该河口是大气中 N2O 的来源。在河口淡水端，沉积物中一氧化二氮的流出量与上覆水中的亚硝酸盐浓度以及流入沉积物中的亚硝酸盐密切相关。添加亚硝酸盐时沉积物中 N2O 产量的增加量比添加硝酸盐时增加约 10 倍。与硝酸盐浓度相比，增加亚硝酸盐对反硝化作用的刺激程度更大。在550 μM亚硝酸盐或硝酸盐（使用的最高浓度）下，亚硝酸盐的反硝化速率为600 μmol N (.) m(-2) (.) h(-1)，但硝酸盐的反硝化速率仅为180 μmol N (.) m(-2) (.) h(-1)。添加亚硝酸盐（反硝化作用7%～13%）的一氧化二氮生成率与反硝化作用的比率（N2O/N-2×100）显着高于添加硝酸盐（反硝化作用2%～4%）的情况。结果表明，除了在河口沉积物中拥有形成N-2的完整反硝化途径的厌氧细菌之外，可能还存在另外两类细菌：亚硝酸盐反硝化细菌，其通过N2O将亚硝酸盐还原为N-2，以及专性亚硝酸盐反硝化细菌，其将亚硝酸盐还原为N2O作为最终产物。考虑N2O形成过程中自由能的变化，得出这样的结论：在科恩河口，使用亚硝酸盐作为电子受体形成N2O是有利的，并且可能是调节高营养负荷河口N2O形成的关键因素。
Nitrate and nitrite concentrations in the water and nitrous oxide and nitrite fluxes across the sediment-water interface were measured monthly in the River Colne estuary, England, from December 1996 to March 1998. Water column concentrations of N2O in the Colne were supersaturated with respect to air, indicating that the estuary was a source of N2O for the atmosphere. At the freshwater end of the estuary, nitrous oxide effluxes from the sediment were closely correlated with the nitrite concentrations in the overlying water and with the nitrite influx into the sediment. Increases in N2O production from sediments were about 10 times greater with the addition of nitrite than with the addition of nitrate. Rates of denitrification were stimulated to a larger extent by enhanced nitrite than by nitrate concentrations. At 550 muM nitrite or nitrate (the highest concentration used), the rates of denitrification were 600 mumol N (.) m(-2) (.) h(-1) with nitrite but only 180 mumol N (.) m(-2) (.) h(-1) with nitrate. The ratios of rates of nitrous oxide production and denitrification (N2O/N-2 x 100) were significantly higher with the addition of nitrite (7 to 13% of denitrification) than with nitrate (2 to 4% of denitrification). The results suggested that in addition to anaerobic bacteria, which possess the complete denitrification pathway for N-2 formation in the estuarine sediments, there may be two other groups of bacteria: nitrite denitrifiers, which reduce nitrite to N-2 via N2O, and obligate nitrite-denitrifying bacteria, which reduce nitrite to N2O as the end product. Consideration of free-energy changes during N2O formation led to the conclusion that N2O formation using nitrite as the electron acceptor is favored in the Colne estuary and may be a critical factor regulating the formation of N2O in high-nutrient-load estuaries.