Long-Term Experimental Acidification Drives Watershed Scale Shift in Dissolved Organic Matter Composition and Flux
Long-Term Experimental Acidification Drives Watershed Scale Shift in Dissolved Organic Matter Composition and Flux
复制标题
长期实验酸化驱动溶解有机物成分和通量的流域规模变化
DOI：
10.1021/acs.est.7b04499
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发表时间：
2018
影响因子：
11.4
通讯作者：
McKnight, Diane M.
中科院分区：
文献类型：
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作者：
SanClements, Michael D.;Fernandez, Ivan J.;Lee, Robert H.;Roberti, Joshua A.;Adams, Mary Beth;Rue, Garret A.;McKnight, Diane M.
在过去的几十年里，北半球大部分地区地表水中溶解的有机碳浓度（DOC）有所增加。关于这一现象的驱动因素，人们提出了几种假设，包括通过酸度变化机制减少硫 (S) 沉积。使用荧光光谱和来自两个长期（完成本研究超过 24 年）整个流域酸化实验（即缅因州的 Bear Brook Watershed (BBWM) 和西弗吉尼亚州的 Fernow Experimental Forest (FEF)）的数据，使我们能够控制酸度变化机制以外的因素（例如，不同的植被、气候变化），从而产生了我们所知道的第一项研究，其中酸度变化机制可以在整个生态系统和十年尺度上通过实验分离出来。 DOM 动态变化的驱动因素。 BBWM 的数十年河流化学记录表明，与参考流域相比，处理后的 DOC 浓度显着降低。此外，在 BBWM 和 FEF 中，我们发现处理流域和参考流域之间的流荧光指数 (FI) 存在显着且持续的差异，其中参考流域表现出更强的陆地 DOM 特征。这些数据，加上上层土壤 pH 值变化的证据，支持了这样的假设：硫沉降的减少正在推动土壤有机质溶解度的变化以及陆地 DOC 向水体通量的增加。
Over the last several decades dissolved organic carbon concentrations (DOC) in surface waters have increased throughout much of the northern hemisphere. Several hypotheses have been proposed regarding the drivers of this phenomenon including decreased sulfur (S) deposition working via an acidity- change mechanism. Using fluorescence spectroscopy and data from two long-term (24+ years at completion of this study) whole watershed acidification experiments, that is, the Bear Brook Watershed in Maine (BBWM) and Fernow Experimental Forest in West Virginia (FEF) allowed us to control for factors other than the acidity-change mechanism (e.g., differing vegetation, shifting climate), resulting in the first study we are aware of where the acidity change mechanism could be experimentally isolated at the whole ecosystem and decadal scales as the driver of shifts in DOM dynamics. The multidecadal record of stream chemistry at BBWM demonstrates a significantly lower DOC concentration in the treated compared to the reference watershed. Additionally, at both BBWM and FEF we found significant and sustained differences in stream fluorescence index (FI) between the treated and reference watersheds, with the reference watersheds demonstrating a stronger terrestrial DOM signature. These data, coupled with evidence of pH shifts in upper soil horizons support the hypotheses that declines in S deposition are driving changes in the solubility of soil organic matter and increased flux of terrestrial DOC to water bodies.