Global distribution of dissolved organic matter along the aquatic continuum: Across rivers, lakes and oceans
Global distribution of dissolved organic matter along the aquatic continuum: Across rivers, lakes and oceans
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DOI：
10.1016/j.scitotenv.2017.07.076
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发表时间：
2017-12-31
影响因子：
9.8
通讯作者：
Markager, Stiig
中科院分区：
文献类型：
--
作者：
Massicotte, Philippe;Asmala, Eero;Markager, Stiig
基于广泛的文献调查，包含超过12，000对溶解有机碳（DOC）浓度和有色溶解有机物（CDOM）的吸收分布在四大洲和七个大洋的配对测量，我们描述了溶解有机物（DOM）的全球分布和转化沿着水连续体跨越河流和湖泊到海洋。DOC浓度和CDOM在350 nm处的吸收在全球范围内观察到一个很强的对数线性关系（R-2 = 0.92），但被认为是生态系统依赖的地方和区域尺度。我们的研究结果表明，DOM被运往海洋，所观察到的关系的鲁棒性迅速下降（R-2从0.94到0.44），表明DOC和CDOM之间逐渐脱钩。这可能反映了景观和DOM之间的连接性下降沿着水生连续体。为了支持这一假设，我们使用DOC特定的UV吸光度（苏瓦）来表征DOM池的反应性，DOM池沿着水生连续体从4.9 m（2）x gC（-1）沿着降低。在整个连续体中，逐段线性回归表明，所观察到的苏瓦的减少发生在淡水生态系统比海水生态系统更快，这表明不同的降解过程优先作用于CDOM，而不是碳含量。所观察到的DOM特性的变化沿着水生连续体也表明，陆地DOM池逐渐变得不那么活跃，这对水生生态系统中的有机碳循环有着深远的影响。(C)2017爱思唯尔B. V.保留所有权利。
Based on an extensive literature survey containing more than 12,000 paired measurements of dissolved organic carbon (DOC) concentrations and absorption of chromophoric dissolved organic matter (CDOM) distributed over four continents and seven oceans, we described the global distribution and transformation of dissolved organic matter (DOM) along the aquatic continuum across rivers and lakes to oceans. A strong log-linear relationship (R-2 = 0.92) between DOC concentration and CDOM absorption at 350 nm was observed at a global scale, but was found to be ecosystem-dependent at local and regional scales. Our results reveal that as DOM is transported towards the oceans, the robustness of the observed relation decreases rapidly (R-2 from 0.94 to 0.44) indicating a gradual decoupling between DOC and CDOM. This likely reflects the decreased connectivity between the landscape and DOM along the aquatic continuum. To support this hypothesis, we used the DOC-specific UV absorbance (SUVA) to characterize the reactivity of the DOM pool which decreased from 4.9 to 1.7 m(2) x gC(-1) along the aquatic continuum. Across the continuum, a piece wise linear regression showed that the observed decrease of SUVA occurred more rapidly in freshwater ecosystems compared to marine water ecosystems, suggesting that the different degradation processes act preferentially on CDOM rather than carbon content. The observed change in the DOM characteristics along the aquatic continuum also suggests that the terrestrial DOM pool is gradually becoming less reactive, which has profound consequences on cycling of organic carbon in aquatic ecosystems. (C) 2017 Elsevier B.V. All rights reserved.