Increased temperature sensitivity of net DOC production from ombrotrophic peat due to water table draw-down
Increased temperature sensitivity of net DOC production from ombrotrophic peat due to water table draw-down
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DOI：
10.1111/j.1365-2486.2008.01683.x
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发表时间：
2009-04-01
影响因子：
11.6
通讯作者：
Heathwaite, A. L.
中科院分区：
文献类型：
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作者：
Clark, J. M.;Ashley, D.;Heathwaite, A. L.
泥炭土中溶解有机碳（DOC）的产生和释放被认为对气候变化敏感，特别是温度和降雨量的变化。然而，很少有人知道的实际速率的净DOC生产响应温度和水位下降，特别是在比较二氧化碳（CO2）通量。为了探索这些关系，我们进行了一个实验室实验，在控制温度和地下水位条件下，完整的泥炭土芯，以确定这些气候因素的影响和相互作用的净DOC生产。我们发现温度，地下水位下降和整个土芯（0至-55 cm深度）的DOC净产量之间存在显着的交互作用（P < 0.001）。这对应于Q（10）（即在10摄氏度范围内净DOC生产率的上升）从高水位和厌氧条件下的1.84增加到-10和-40厘米深度之间的水位下降和有氧条件下的3.53。然而，只有在地下水位恢复到地表后，土壤水化学的二次变化驱动的硫氧化还原反应降低DOC溶解度，因此DOC浓度增加，在地下水位下降期间。此外，DOC的净微生物消耗也很明显，在-1厘米的深度，是一个额外的原因，DOC浓度下降，在干燥期间。因此，虽然温度升高和降雨量减少可能会有显着的影响，从泥炭地的DOC净释放，这些气候效应可以被掩盖的其他因素控制DOC的生物消耗，除了土壤水化学和DOC溶解度。这些研究结果突出了DOC释放的敏感性，从湿地泥炭的水位下降的情景变化，以及需要解开复杂的和相互作用的控制DOC动态，以充分了解环境变化对这个系统的影响。
The production and release of dissolved organic carbon (DOC) from peat soils is thought to be sensitive to changes in climate, specifically changes in temperature and rainfall. However, little is known about the actual rates of net DOC production in response to temperature and water table draw-down, particularly in comparison to carbon dioxide (CO2) fluxes. To explore these relationships, we carried out a laboratory experiment on intact peat soil cores under controlled temperature and water table conditions to determine the impact and interaction of each of these climatic factors on net DOC production. We found a significant interaction (P < 0.001) between temperature, water table draw-down and net DOC production across the whole soil core (0 to -55 cm depth). This corresponded to an increase in the Q(10) (i.e. rise in the rate of net DOC production over a 10 degrees C range) from 1.84 under high water tables and anaerobic conditions to 3.53 under water table draw-down and aerobic conditions between -10 and - 40 cm depth. However, increases in net DOC production were only seen after water tables recovered to the surface as secondary changes in soil water chemistry driven by sulphur redox reactions decreased DOC solubility, and therefore DOC concentrations, during periods of water table draw-down. Furthermore, net microbial consumption of DOC was also apparent at - 1 cm depth and was an additional cause of declining DOC concentrations during dry periods. Therefore, although increased temperature and decreased rainfall could have a significant effect on net DOC release from peatlands, these climatic effects could be masked by other factors controlling the biological consumption of DOC in addition to soil water chemistry and DOC solubility. These findings highlight both the sensitivity of DOC release from ombrotrophic peat to episodic changes in water table draw-down, and the need to disentangle complex and interacting controls on DOC dynamics to fully understand the impact of environmental change on this system.