Dynamics of dissolved organic matter in riverine sediments affected by weir impoundments: Production, benthic flux, and environmental implications
Dynamics of dissolved organic matter in riverine sediments affected by weir impoundments: Production, benthic flux, and environmental implications
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DOI：
10.1016/j.watres.2017.05.022
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发表时间：
2017-09-15
期刊：
影响因子：
12.8
通讯作者：
Hur, Jin
中科院分区：
文献类型：
--
作者：
Chen, Meilian;Kim, Sung-Han;Hur, Jin
为了了解受水库影响的河流沉积物中溶解有机质（DOM）的特征和动态，我们研究了位于韩国主要河流堰上游的4种不同核心沉积物中DOM的垂直剖面和底栖生物通量。4个样点中有3个样点溶解有机碳（DOC）随深度呈指数积累，并具有季节变化特征。除Fe（II）低于检测限的部位外，DOC随深度积累的总体趋势与Fe（II）和NH4+的增加以及PO43-的减少同时发生，表明DOM动力学与铁还原厌氧呼吸密切相关，这是早期成岩作用的重要途径。岩心底栖生物通量的估算表明，沉积物可能作为DOC、显色DOM （CDOM）和荧光DOM （FDOM）源进入上覆水体。基于DOC的底栖生物外溢量与之前报告的湖泊和沿海地区相当，CDOM和FDOM的外溢量甚至更高。这些发现表明，受蓄水影响的河流系统会改变上覆水的DOM组成，最终影响后续的水处理过程，如消毒副产物的产生和膜污染。一个简单的质量平衡模型表明，受蓄水影响的河流沉积物可能在环境中发挥净碳汇的作用，因为与估计的底栖生物外排和沉积物生物呼吸相比，其沉积程度更大。(C) 2017 Elsevier Ltd.版权所有。
In order to understand the characteristics and dynamics of dissolved organic matter (DOM) in the sediment of rivers affected by impoundments, we examined the vertical profiles and the benthic fluxes of DOM in four different core sediments located at upstream sites of weirs in major rivers of South Korea. In three out of four sites, exponential accumulation of dissolved organic carbon (DOC) with depth was observed with the signature of seasonal variability. Except for the site displaying a below-detection limit of Fe(II), the general accumulation trends of DOC with depth was concurrent with the increases of Fe(II) and NH4+ and the decrease of PO43-, signifying a close linkage of the DOM dynamics with anaerobic respiration via iron reduction, an important early diagenesis pathway. The estimated benthic fluxes from the cores revealed that the sediments likely serve as DOC, chromophoric DOM (CDOM), and fluorescent DOM (FDOM) sources to the overlying water. The benthic effluxes based on DOC were comparable to the ranges previously reported in lake and coastal areas, and those of CDOM and FDOM showed even higher levels. These findings imply that impoundment-affected river systems would change the DOM composition of the overlying water, ultimately influencing the subsequent water treatment processes such as disinfection byproducts production and membrane fouling. A simple mass balance model indicated that the impoundment-affected river sediments may operate as a net carbon sink in the environments due to a greater extent of sedimentation compared to the estimated benthic efflux and sediment biological respiration. (C) 2017 Elsevier Ltd. All rights reserved.