Effect of a nitrogen pulse on ecosystem N processing at different temperatures: A mesocosm experiment with (NO3-)-N-15 addition
Effect of a nitrogen pulse on ecosystem N processing at different temperatures: A mesocosm experiment with (NO3-)-N-15 addition
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不同温度下氮脉冲对生态系统氮处理的影响：添加 (NO3-)-N-15 的中生态系统实验
DOI：
10.1111/fwb.12940
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发表时间：
2017
影响因子：
2.7
通讯作者：
Risgaard-Petersen Nils
中科院分区：
文献类型：
--
作者：
Olsen Saara;Cao Yu;Florencia Gutierrez Maria;Brucet S;ra;L;kildehus Frank;Lauridsen Torben L.;Davidson Thomas A.;Sondergaard Martin;Jeppesen Erik;Risgaard-Petersen Nils
浅水湖泊通过处理、转移和保留输入的氮素，对流域氮素平衡发挥重要作用。风暴引起的短期氮脉冲频率的增加和水温的升高都可能是气候变化的结果，可能影响湖泊中的N处理。K15 NO3 −脉冲添加实验（NO3−浓度从0.1增加到2 mg/L）在12个相对较低的中型生态系统中进行。（适用于丹麦湖泊）总氮（TN）和总磷（TP）浓度（约0.3 mg N L-1和0.04 mg P L-1），以评估氮脉冲对浅湖生态系统中氮处理和储存的影响。中型生态系统的水力停留时间约为两个半月，在实验时，它们已经适应了10年的对比温度：环境温度，T3（供暖根据政府间气候变化专门委员会2007年A2情景，+3.7-4.5°C，取决于季节）和T5（A2 + 50%，+4.9-6.6°C加热）。大型植物和丝状藻类分别保留了高达40%和30%的添加的15 N，反映了它们在中围生态系统中的高生物量。大型植物和丝状藻类构成的70%和80%之间的生物量的所有初级生产者在T3和环境处理的实验期间，在T5之间的20%和40%。相比之下，不到1%的15 N扩散到沉积物中，不到5%的15 N作为N2气体损失到大气中。蜗牛代表了15 N的长期储存，保留了高达6%的示踪剂，并在添加示踪剂后100天可检测到富集。我们发现脉冲给药后的15 N周转率在温度处理之间没有显著差异。然而，更大比例的15 N储存在大型植物中的环境和T3围隔，反映了较高的生物量比T5丝状藻类更丰富。因此，大型植物和丝状藻类，而不是温度的关键控制器的N处理在夏季N脉冲在这些浅，TP相对较低的湖泊。
Shallow lakes may play an important role for the nitrogen (N) balance in drainage basins by processing, transferring and retaining N inputs. An increase in the frequency of storm‐induced short‐term N pulses and increased water temperatures are both likely outcomes of climate change, potentially affecting the N processing in lakes.An experiment with a K15NO3−pulse addition (increase in NO3−concentration fromc.0.1 to 2 mg/L) was carried out in 12 mesocosms with relatively low (applies to Danish lakes) total N (TN) and total phosphorus (TP) concentrations (c. 0.3 mg N L−1and 0.04 mg P L−1) to assess the effects of an N pulse on N processing and storage in shallow lake ecosystems. The mesocosms have a hydraulic retention time of approximately two and a half months, and at the time of the experiment, they had been adapted to contrasting temperatures for a period of 10 years: ambient, T3 (heating according to the Intergovernmental Panel on Climate Change 2007 A2 scenario, +3.7–4.5°C, depending on season) and T5 (heating with A2 + 50%, +4.9–6.6°C).Macrophytes and filamentous algae retained up to 40% and 30% of the added15N, respectively, reflecting their high biomass in the mesocosms. Macrophytes and filamentous algae constituted between 70% and 80% of the biomass of all primary producers during the experiment in the T3 and ambient treatments and between 20% and 40% in T5. By comparison, less than 1% of the added15N diffused to the sediment and less than 5% was lost to the atmosphere as N2gas. Snails represented the long‐term storage of15N, retaining up to 6% of the tracer and with detectable enrichment 100 days after tracer addition.We found no significant differences among the temperature treatments in the15N turnover after pulse dosing. However, a larger percentage of15N was stored in macrophytes in the ambient and T3 mesocosms, reflecting higher biomasses than in T5 where filamentous algae were more abundant. Macrophytes and filamentous algae rather than temperature were therefore key controllers of N processing during the summer N pulse in these shallow, relatively low TP lakes.