Xue Shuang, Wang Chao, Zhang Zhaohong, Song Youtao, Liu Qiang
School of Environmental Science, Liaoning University, Shenyang 110036, China.
School of Environmental Science, Liaoning University, Shenyang 110036, China.
Chemosphere. 2016 Feb;144:816-26. doi: 10.1016/j.chemosphere.2015.09.059. Epub 2015 Sep 27.
The photodegradation behavior of dissolved organic matter (DOM) with different origins in ice under solar irradiation was investigated. Exposure to sunlight at 2.7 × 10(5) J m(-2) resulted in dissolved organic carbon (DOC) reductions of 22.1-36.5% in ice. The naturally occurring DOM had higher photodegradation potentials than the wastewater-derived DOM in ice. Ultraviolet (UV)-absorbing compounds in DOM, regardless of DOM origin, had much higher photodegradation potentials than gross DOC in ice. The susceptibility of UV-absorbing compounds with natural origin to sunlight exposure in ice was higher than those derived from wastewater. Trihalomethane (THM) precursors were more susceptible to photochemical reactions than gross DOC and haloacetic acid (HAA) precursors in ice. THM precursors in naturally occurring DOM were more photoreactive than those in wastewater-derived DOM in ice, while the photoreactivity of HAA precursors in ice was independent of DOM origin. In ice, the photoreactivity of humic-like fluorescent materials, regardless of DOM origin, was higher than that of gross DOC and protein-like fluorescent materials. DOC reductions caused by sunlight irradiation were found to be negatively correlated to DOC levels, and positively correlated to the aromaticity of DOM. The photodegradation of both wastewater-derived and naturally occurring DOM in ice was significantly facilitated at both acid and alkaline pH, as compared to neutral pH. The photodegradation of DOM in ice, regardless of the origin, was facilitated by nitrate ion [Formula: see text] , nitrite ion [Formula: see text] , ferric ion (Fe(3+)) and ferrous ion (Fe(2+)), and on the other hand, was inhibited by chloridion ion (Cl(-)) and copper ion (Cu(2+)).
研究了不同来源的溶解有机物（DOM）在冰中受太阳辐射时的光降解行为。在2.7×10⁵ J m⁻²的阳光照射下，冰中溶解有机碳（DOC）减少了22.1% - 36.5%。天然存在的DOM在冰中的光降解潜力高于废水来源的DOM。DOM中的紫外线（UV）吸收化合物，无论DOM来源如何，在冰中的光降解潜力都比总DOC高得多。天然来源的UV吸收化合物在冰中对阳光照射的敏感性高于废水来源的。在冰中，三卤甲烷（THM）前体比总DOC和卤乙酸（HAA）前体更容易发生光化学反应。天然存在的DOM中的THM前体在冰中的光反应性比废水来源的DOM中的更高，而冰中HAA前体的光反应性与DOM来源无关。在冰中，无论DOM来源如何，类腐殖质荧光物质的光反应性都高于总DOC和类蛋白质荧光物质。发现阳光照射引起的DOC减少与DOC水平呈负相关，与DOM的芳香性呈正相关。与中性pH相比，酸性和碱性pH均显著促进了冰中废水来源和天然存在的DOM的光降解。无论来源如何，冰中DOM的光降解都受到硝酸根离子[化学式：见原文]、亚硝酸根离子[化学式：见原文]、铁离子（Fe³⁺）和亚铁离子（Fe²⁺）的促进，另一方面，受到氯离子（Cl⁻）和铜离子（Cu²⁺）的抑制。
