School of Environmental Science, Liaoning University, Shenyang 110036, China.
School of Environmental Science, Liaoning University, Shenyang 110036, China.
Water Res. 2023 Nov 1;246:120714. doi: 10.1016/j.watres.2023.120714. Epub 2023 Oct 9.
Dissolved organic matter (DOM) is an ubiquitous component of environmental snow and ice, which can absorb light and produce reactive species (RS) and thus is of importance in ice photochemistry. The photodegradation of sulfachloropyridazine (SCP) without and with DOM present in liquid water and ice were investigated in this study. The photodegradation rate constants for SCP without DOM present was enhanced by 52.5 % in ice relative to liquid water, likely due to the enhanced role of SCP self-sensitized RS in ice. DOM significantly promoted SCP photolysis in both liquid water and ice, which was mainly attributed to roles of singlet oxygen (O) and triplet excited-state DOM (DOM*) generated from DOM. O production from DOM was significantly enhanced in ice relative to liquid water. Hydroxyl radical (OH) production from DOM in ice was similar to those in liquid water. Enhancement in DOM* production in ice was observed at low DOM concentrations. Suwannee River Fulvic Acid (SRFA) and Elliott Soil Humic Acid (ESHA) exhibited differences in RS production in liquid water and ice, as well as in enhancement of O and DOM* produced in ice relative to liquid water. DOM induced reaction pathways of SCP different from those without DOM present, and therefore affected toxicity of SCP photoproducts. There were differences in photodegradation pathways of SCP as well as in toxicity of SCP photoproducts between liquid water and ice.
溶解有机物（DOM）是环境雪中普遍存在的组成部分，它可以吸收光并产生活性物质（RS），因此在冰光化学中很重要。本研究考察了在液态水和冰中存在和不存在 DOM 时磺胺氯哒嗪（SCP）的光降解。与液态水相比，不存在 DOM 时 SCP 的光降解速率常数在冰中提高了 52.5%，这可能是由于 SCP 自敏化 RS 在冰中的增强作用。DOM 显著促进了液态水和冰中 SCP 的光解，这主要归因于 DOM 产生的单线态氧（O）和三重激发态 DOM（DOM*）的作用。与液态水相比，DOM 在冰中产生 O 的能力显著增强。DOM 在冰中的 OH 生成与在液态水中相似。在低 DOM 浓度下观察到 DOM在冰中的生成增强。苏万尼河富里酸（SRFA）和艾略特土壤腐殖酸（ESHA）在液态水和冰中产生 RS 的能力以及在冰中相对于液态水产生 O 和 DOM的能力存在差异。DOM 诱导了 SCP 的反应途径与不存在 DOM 时不同，从而影响了 SCP 光产物的毒性。SCP 的光降解途径以及 SCP 光产物的毒性在液态水和冰之间存在差异。
