Lability of dissolved organic carbon from boreal peatlands: interactions between permafrost thaw, wildfire, and season1
Lability of dissolved organic carbon from boreal peatlands: interactions between permafrost thaw, wildfire, and season1
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北方泥炭地溶解有机碳的不稳定性：永久冻土融化、野火和季节之间的相互作用1
DOI：
10.1139/cjss-2019-0154
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发表时间：
2020
影响因子：
1.7
通讯作者：
D. Olefeldt
中科院分区：
文献类型：
--
作者：
K. Burd;Cristian Estop‐Aragonés;S. Tank;D. Olefeldt
摘要/ Abstract摘要：北方泥炭地是下游水生生态系统溶解有机碳（DOC）的主要来源，影响着碳循环和食物网结构。野火和永久冻土融化改变泥炭地植被和水文，并可能影响出口DOC的数量和化学成分。我们研究了野火和解冻对近地表孔隙水DOC的微生物和光化学稳定性的影响，通过7 d的培养来评估。我们在春季、夏季和秋季进行了这些孵育，但只发现了春季的差异，当DOC的芳香性和C/N比较低时，DOC的生物降解性（黑暗孵育期间的损失率%）增加。在春季，沿塌陷的泥炭高原边缘形成的热岩溶沼泽最不稳定的DOC（损失25%），大于热岩溶沼泽成熟剖面（损失3%）和冻土带完整的泥炭高原（损失9%）。解冻后DOC稳定性的增加可能与生产性亲水性泥炭藓类和莎草类的高DOC产量和周转量有关，而不是与解冻的永久冻土泥炭有关。一场野火（3年前）降低了泥炭高原（4%）和迅速崩塌的泥炭高原边缘（14%）的DOC生物可降解性。各监测点夏季和秋季DOC的生物降解率均较低；分别为2%和4%。光降解被证明对下游DOC的降解有潜在的显著贡献，但在泥炭地的不同地点没有变化。我们发现，永久冻土融化和野火等干扰有可能影响下游的碳循环，特别是在泥炭地与下游水生生态系统连接良好的春季，影响最大。
Abstract: Boreal peatlands are major sources of dissolved organic carbon (DOC) to downstream aquatic ecosystems, where it influences carbon cycling and food web structure. Wildfire and permafrost thaw alter peatland vegetation and hydrology and may affect the quantity and chemical composition of exported DOC. We studied the influence of wildfire and thaw on microbial and photochemical lability of near-surface porewater DOC, assessed through 7 d incubations. We carried out these incubations in spring, summer, and fall but only found differences in spring when DOC biodegradability (% loss during dark incubations) increased with lower DOC aromaticity and C/N ratios. During spring, the most labile DOC was found in recently formed thermokarst bogs along collapsing peat plateau edges (25% loss), which was greater than in mature sections of thermokarst bogs (3%), and peat plateaus with intact permafrost (9%). Increased DOC lability following thaw was likely linked to high DOC production and turnover associated with productive hydrophilic Sphagnum mosses and sedges, rather than thawed permafrost peat. A wildfire (3 yr prior) reduced DOC biodegradability in both peat plateaus (4%) and rapidly collapsing peat plateau edges (14%). Biodegradability of DOC in summer and fall was low across all sites; 2% and 4%, respectively. Photodegradation was shown to potentially contribute significantly to downstream DOC degradation but did not vary across peatland sites. We show that disturbances such as permafrost thaw and wildfire have the potential to affect downstream carbon cycling, particularly as the largest influences were found in spring when peatlands are well connected to downstream aquatic ecosystems.
影响因子：
9.7
作者：
Estop-Aragones, Cristian;Cooper, Mark D. A.;Hartley, Iain P.
通讯作者：
Hartley, Iain P.