The quality of dissolved organic carbon (DOC) affects both carbon cycling in surface waters and drinking water production. Not much is known about the influence of environmental conditions on DOC quality. We studied the effect of redox conditions on the chemical composition of DOC in a drinking water reservoir by Fourier transform ion cyclotron resonance mass spectrometry in combination with sediment core incubation experiments under manipulated redox conditions. We observed clear differences in DOC quality among oxic epilimnion, anoxic hypolimnion, and sediment porewater. Sediment porewater showed relatively high intensities of polyphenol-like components with H/C ratios of <1 and O/C ratios of >0.6. Consistent with this, anoxic incubation of a sediment core resulted in an accumulation of these components in the overlying water. The observed pattern of DOC quality change can be explained by redox-dependent adsorption/desorption of DOC on iron minerals. Under oxic conditions, the polyphenol-like components bind on freshly formed iron hydroxides, a process that affects both DOC stability in surface waters and treatability during drinking water production.

中文翻译：

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氧化还原条件影响分层淡水中溶解的有机碳质量

溶解有机碳（DOC）的质量会影响地表水中的碳循环和饮用水生产。关于环境条件对DOC质量的影响知之甚少。我们通过傅里叶变换离子回旋共振共振质谱结合受控氧化还原条件下的沉积物核心孵育实验，研究了氧化还原条件对饮用水中DOC化学成分的影响。我们观察到在氧化epi水，缺氧水lim和沉积物孔隙水之间的DOC质量存在明显差异。沉积物孔隙水表现出相对较高的多酚状组分强度，H / C比<1，O / C比> 0.6。与此相一致，沉积物核心的缺氧孵育导致这些成分在上覆水中积聚。观察到的DOC质量变化模式可以通过氧化还原依赖的DOC在铁矿物质上的吸附/解吸来解释。在有氧条件下，类似多酚的成分结合在新形成的氢氧化铁上，该过程会影响地表水中的DOC稳定性和饮用水生产过程中的可处理性。