作 者：
Evan S. Kane;Lynn R. Mazzoleni;Carley J. Kratz;John A. Hribljan;Christopher P. Johnson;Thomas G. Pypker;Rodney Chimner;赵旋琪;王江静;赵红艳;刘莎莎
单 位：
东北师范大学地理科学学院;美国密歇根科技大学森林资源与环境科学学院
关键词：
泥炭;气候变化;细胞外的酶;溶解有机氮;溶解有机碳;杜鹃花科;莎草科
摘 要：
北欧和北美的研究表明,近几十年来水生生态系统中溶解有机碳(DOC)浓度增加。尽管关于溶解有机碳提高的机制还没有定论,但是一般认为其根本原因在于升温、降水变率增加和大气沉降变化等气候变化因素。本实验历时长达3年,通过在泥炭地上方1.24 m处安装红外灯积极增温,测试了增温对泥炭孔隙水组成的影响。结果发现在泥炭地下5 c m处,生长季中各处理的平均温度(n=5)比对照处理高1.9±0.4℃(t=5.03,P=0.007)。同时,在泥炭地下25 c m处,生长季中各处理的孔隙水D O C浓度(73.4±3.2 m g/L)比对照处理(63.7±2.1 m g/L)高15%(t=4.69,P<0.001)。此外,升温后的处理中,D O C分解速率是实验室内对照处理的2倍,芳香性比对照组孔隙水更低(增温后泥炭在254 nm处的吸光度降低)。溶解有机氮(DON)浓度变化规律与DOC一致,每单位碳中溶解的氮随着温度升高而下降。以往的研究表明,在这个实验地,增温使净初级生产力增加;同时,几丁质酶和葡萄苷酶的活性增加。本实验观察到,增温条件下DOC浓度增加,可能是因为根际微生物和植物相互作用的结果。在能去质子化生物分子池中,也探测到增温后出现较多的、独特的含有较高双键(DBE)的含氮化合物(在通过超高分辨率离子电喷雾质谱鉴定达到的所有化合物中占16%),这些化合物可能是随着增温引起的植物、微生物和酶活性增加后的产物。随着泥炭地持续升温,相对不稳定的DOC含量升高,这可能导致地表径流中DOC浓度增加,还可能作为有效的电子供体(或者受体)源使陆地和水生环境中的CO2和CH4增加。
译 名：
Peat Porewater Dissolved Organic Carbon Concentration and Lability Increase with Warming: a Field Temperature Manipulation Experiment in a Poor-fen
作 者：
Evan S. Kane;Lynn R. Mazzoleni;Carley J. Kratz;John A. Hribljan;Christopher P. Johnson;Thomas G. Pypker;Rodney Chimner;Zhao Xuanqi;Wang Jiangjing;Zhao Hongyan;Liu Shasha;School of Forest Resources and Environmental Science,USA Michigan Technological University;School of Geography Sciences,Northeast Normal University;
关键词：
peat;;climate change;;extracellular enzyme;;dissolved organic nitrogen;;dissolved organic carbon;;Ericaceae;;sedge
摘 要：
Studies conducted across northern Europe and North America have shown increases in dissolved organic carbon(DOC) in aquatic systems in recent decades. While there is little consensus as to the exact mechanisms for the increases in DOC, hypotheses converge on such climate change factors as warming, increased precipitation variability, and changes in atmospheric deposition. In this study, we tested the effects of warming on peat porewater composition by actively warming a peatland with infrared lamps mounted 1.24 m above the peat surface for 3 years. Mean growingseason peat temperatures in the warmed plots(n=5) were 1.9±0.4 ℃ warmer than the control plots at 5 cm depth(t statistic=5.03, P=0.007). Mean porewater DOC concentrations measured throughout the growing season were 15% higher in the warmed plots(73.4±3.2 mg/L) than in the control plots(63.7±2.1 mg/L) at 25 cm(t=4.69, P<0.001). Furthermore, DOC from the warmed plots decayed nearly twice as fast as control plot DOC in laboratory incubations, and exhibited lower aromaticity than control plot porewater(reduction in SUVA254 in heated plots compared with control plots). Dissolved organic nitrogen(DON) concentrations tracked DOC patterns as expected, but the amount of dissolved N per unit C decreased with warming. Previous work has shown that warming increased net primary production at this site, and together with measured increases in the activities of chitinases and glucosidases we suggest that the increased DOC concentrations observed with warming were derived in part from microbial-plant interactions in the rhizosphere. We also detected more nitrogen containing compounds with higher double bond equivalents(DBE) unique to the warmed plots, within the pool of biomolecules able to deprotonate(16% of all compounds identified using ultrahigh resolution ion electrospray mass spectrometry); we suggest these compounds could be the products of increased plant, microbial, and enzyme activity occurring with warming. With continued warming in peatlands, an increase in relatively labile DOC concentrations could contribute to dissolved exports of DOC in runoff, and would likely contribute to the pool of efficient electron donors(and acceptors) in the production of CO2 and CH4 in terrestrial and aquatic environments.
