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首页> 外文期刊>Ecological Applications >Denitrification and the nitrogen budget of a reservoir in an agricultural landscape
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Denitrification and the nitrogen budget of a reservoir in an agricultural landscape

机译：农业景观中水库的反硝化与氮收支。

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Denitrification is an important process in aquatic sediments, but its role has not been assessed in the N mass balance of upper-Midwestern (USA) reservoirs that receive large agricultural riverine N inputs. We used a 4400-ha reservoir to determine the role of denitrification in the N mass balance and effectiveness in reducing downstream transport of NO3-N. Sediment denitrification was (1) measured monthly (March 2002 March 2003) at eight sites in the Lake Shelbyville reservoir in central Illinois using the acetylene inhibition, chloramphenicol technique, (2) scaled to the overall reservoir and compared to N not accounted for in a mass balance, and (3) estimated indirectly using long-term (1981-2003) mass balances of N in the reservoir. Denitrification rates in the reservoir were high during spring and early summer of 2002, when maximum NO3-N concentrations were measured (1014 mg NO3-N/L). We estimated that denitrification for the year was between 2580 and 5150 Mg N. Missing N from the mass balance was 3004 Mg N, suggesting that sediment denitrification was the sink. Areal rates of sediment denitrification in the reservoir ranged from 62 to 225 g N.m(-2).yr(-1), with rates a function of both denitrification intensity (mu g N.g dry mass.h(-1)) and the overall mass of sediment present. From 1981 to 2003 the average NO3-N inlet flux was 8900 Mg N/yr. About 58% of the total NO3-N input was removed, and annual NO3-N removed as a percentage of inputs was significantly related to reservoir retention time (average = 0.36 yr for the 23 years, range = 0.21-0.84 yr). By scaling denitrification in Lake Shelbyville to other reservoirs in Illinois, we estimated a sink of 48900 Mg N/yr. When combined with estimated in-stream denitrification, 60900 Mg N/yr was estimated to be removed by sediment denitrification. This reduces riverine export from Illinois to the Gulf of Mexico, where the flux during the 1990s was about 244000 Mg N/yr, and illustrates the importance of reservoir denitrification as an N sink in Midwestern agricultural landscapes.
机译：反硝化作用是水生沉积物中的重要过程，但尚未在接受大量农业河流氮输入的中西部（美国）水库的氮质量平衡中评估其作用。我们使用了一个4400公顷的水库来确定反硝化在氮素质量平衡中的作用以及减少NO3-N下游传输的有效性。 （1）使用乙炔抑制氯霉素技术在伊利诺伊州中部谢尔比维尔湖水库的八个位置每月进行沉积物反硝化测量（2002年3月2002年），（2）缩放至总储量，并与未计入氮的N进行比较质量平衡，以及（3）使用储层中氮的长期（1981-2003年）间接估算值。在2002年春季和初夏，当测量最大NO3-N浓度（1014 mg NO3-N / L）时，储层中的反硝化率很高。我们估计该年度的反硝化作用介于2580和5150 Mg N之间。质量平衡中缺少的N为3004 Mg N，这表明沉积物的反硝化作用就是汇。水库中沉积物反硝化的区域速率介于62到225 g Nm（-2）.yr（-1）之间，速率与反硝化强度（g g Ng干质量.h（-1））和总体反硝化强度有关。存在的沉积物质量。从1981年到2003年，平均NO3-N入口通量为8900 Mg N / yr。去除了大约58％的NO3-N投入，每年去除的NO3-N占投入的百分比与储层保留时间显着相关（23年平均值= 0.36年，范围= 0.21-0.84年）。通过将谢尔比维尔湖的反硝化作用扩展到伊利诺伊州的其他水库，我们估计的下沉量为48900 Mg N / yr。当与估计的流内反硝化相结合时，估计通过沉积物反硝化去除了60900 Mg N / yr。这减少了从伊利诺伊州到墨西哥湾的河流出口，1990年代那里的通量约为244000 Mg N / yr，这说明了水库反硝化作为中西部农业景观中N汇的重要性。

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