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首页> 外文期刊>Biogeochemistry >Denitrification kinetics and denitrifier abundances in sediments of lakes receiving atmospheric nitrogen deposition (Colorado, USA)
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Denitrification kinetics and denitrifier abundances in sediments of lakes receiving atmospheric nitrogen deposition (Colorado, USA)

机译：接受大气氮沉积的湖泊沉积物中的反硝化动力学和反硝化丰度（美国科罗拉多州）

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摘要

The transport and deposition of anthropogenic nitrogen (N) to downwind ecosystems is significant and can be a dominant source of new N to many watersheds. Bacterially mediated denitrification in lake sediments may ameliorate the effects of N loading by permanently removing such inputs. We measured denitrification in sediments collected from lakes in the Colorado Rocky Mountains (USA) receiving elevated (5-8 kg N ha(-1) y(-1)) or low (< 2 kg N ha(-1) y(-1)) inputs of atmospheric N deposition. The nitrate (NO3 (-)) concentration was significantly greater in high-deposition lakes (11.3 mu mol l(-1)) compared to low-deposition lakes (3.3 mu mol l(-1)). Background denitrification was positively related to NO3 (-) concentrations and we estimate that the sampled lakes are capable of removing a significant portion of N inputs via sediment denitrification. We also conducted a dose-response experiment to determine whether chronic N loading has altered sediment denitrification capacity. Under Michaelis-Menten kinetics, the maximum denitrification rate and half-saturation NO3 (-) concentration did not differ between deposition regions and were 765 mu mol N m(-2) h(-1) and 293 mu mol l(-1) NO3 (-), respectively, for all lakes. We enumerated the abundances of nitrate- and nitrite-reducing bacteria and found no difference between high- and low-deposition lakes. The abundance of these bacteria was related to available light and bulk sediment resources. Our findings support a growing body of evidence that lakes play an important role in N removal and, furthermore, suggest that current levels of N deposition have not altered the abundance of denitrifying bacteria or saturated the capacity for sediment denitrification.
机译：人为氮（N）向顺风生态系统的运输和沉积非常重要，并且可能成为许多流域新氮的主要来源。通过永久去除此类输入，细菌介导的湖泊沉积物中的反硝化作用可以减轻氮负荷的影响。我们测量了从科罗拉多洛矶山脉（美国）的湖泊收集的沉积物中的反硝化作用，这些沉积物收到的氮含量较高（5-8 kg N ha（-1）y（-1））或较低（<2 kg N ha（-1）y（-） 1））大气氮沉降的输入。与低沉积湖泊（3.3μmol l（-1））相比，高沉积湖泊（11.3μmol l（-1））中的硝酸盐（NO3（-））浓度明显更高。背景反硝化与NO3（-）浓度呈正相关，我们估计，采样的湖泊能够通过沉积物反硝化去除很大一部分N输入。我们还进行了剂量响应实验，以确定长期的氮负荷是否改变了沉积物的反硝化能力。在Michaelis-Menten动力学下，最大反硝化速率和半饱和NO3（-）浓度在沉积区域之间没有差异，分别为765μmol N m（-2）h（-1）和293μmol l（-1）所有湖泊分别为NO3（-）。我们列举了减少硝酸盐和亚硝酸盐的细菌的数量，发现高沉积湖和低沉积湖之间没有差异。这些细菌的丰度与可用的轻质和大量沉积物资源有关。我们的发现支持越来越多的证据表明，湖泊在氮的去除中起着重要的作用，此外，表明当前的氮沉降水平并未改变反硝化细菌的丰度或沉积物反硝化的能力。

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