Diel cycles in the fluorescence of dissolved organic matter in dystrophic Wisconsin seepage lakes: Implications for carbon turnover
Diel cycles in the fluorescence of dissolved organic matter in dystrophic Wisconsin seepage lakes: Implications for carbon turnover
复制标题
威斯康星州营养不良渗漏湖中溶解有机物荧光的狄尔循环：对碳周转的影响
DOI：
10.1002/lno.10026
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发表时间：
2015
影响因子：
4.5
通讯作者：
P. Hanson
中科院分区：
文献类型：
--
作者：
C. Watras;K. Morrison;J. Crawford;C. McDonald;S. Oliver;P. Hanson
我们在几个小时到几个月的时间尺度上监测了威斯康星州两个沼泽湖泊的变色溶解有机物（CDOM）荧光动态。泥炭地衍生的溶解有机质（DOM）是两个沼泽湖泊的主要溶质，昼夜旋回是CDOM荧光时间序列的主要特征。在振幅和时间上观察到两个不同的死亡周期：一个在缺氧的癫痫中，另一个在缺氧、低代谢的水中。这些循环不能归因于仪器人为因素（即温度、环境光或电池电压的每日振荡）、水文强迫或内部过滤、pH值或氧化还原条件的影响。高光消光系数，特别是在紫外区（~ 10 m−1至30 m−1），表明在这些暗水湖泊中，CDOM荧光探针深度的DOM光解作用可以忽略不计（溶解碳浓度：10 mg C L−1至20 mg C L−1）。死亡周期显然主要由介导DOM产生（释放）和破坏（吸收）的生物活动控制。由原始CDOM荧光循环特性得出的碳周转率（0.28 mg C L−1 d−1）与基于每日二氧化碳动态的生态系统净产量（0.32 mg C L−1 d−1）相似。在这些沼泽湖泊中，似乎有一个小的、次要的不稳定有机碳池以相对较高的速率翻转，这与DOM稳定性的双室观点相一致。
We monitored the dynamics of chromophoric dissolved organic matter (CDOM) fluorescence in two Wisconsin bog lakes over timescales ranging from hours to months. Peatland‐derived dissolved organic matter (DOM) was the major solute in both bog lakes, and diel cycles were dominant features of the CDOM fluorescence time series. Two distinct diel cycles that differed in amplitude and timing were observed: one in oxic epilimnia and a second in anoxic, hypolimnetic waters. These cycles were not attributable to instrumental artifacts (i.e., daily oscillations of temperature, ambient light, or battery voltage), hydrologic forcing, or the effects of inner filtering, pH, or redox conditions. High light extinction coefficients, especially in the ultraviolet region (∼ 10 m−1 to 30 m−1), suggest that DOM photolysis was negligible at the depths of the CDOM fluorescence probes in these dark‐water lakes (dissolved carbon concentration: 10 mg C L−1 to 20 mg C L−1). The diel cycles were apparently governed primarily by biological activities that mediate DOM production (release) and destruction (uptake). Rates of carbon turnover derived from properties of the epilimnetic CDOM fluorescence cycle (0.28 mg C L−1 d−1) were similar to rates of net ecosystem production based on daily CO2 dynamics (0.32 mg C L−1 d−1). It appears that a small, secondary pool of labile organic carbon turns over at relatively high rates in these bog lakes, consistent with the two‐compartment view of DOM stability.