Triplet Photochemistry of Effluent and Natural Organic Matter in Whole Water and Isolates from Effluent-Receiving Rivers
Triplet Photochemistry of Effluent and Natural Organic Matter in Whole Water and Isolates from Effluent-Receiving Rivers
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DOI：
10.1021/es505081w
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发表时间：
2015-03-17
影响因子：
11.4
通讯作者：
Mackay, Allison A.
中科院分区：
文献类型：
--
作者：
Bodhipaksha, Laleen C.;Sharpless, Charles M.;Mackay, Allison A.
经处理的城市废水中含有的流出物有机物（EfOM）在组成上不同于天然存在的溶解性有机物（DOM）。因此，EfOM的存在可能会改变河流中活性中间体的光化学生产，这些河流接受经处理的城市废水的可测量的贡献。测量了全水样品和通过固相萃取从三条河流中收集的城市污水处理厂排放上游和下游的全水样品中分离的OM的激发三重态OM（（OM）-O-3*）的量子产率系数和单线态氧（O-1（2））的表观量子产率，所述三条河流接收不同的流出物贡献：Hockanum R.，CT（22%（v/v）流出液流量）、E.福克小迈阿密河，OH（11%）和Pomperaug R.，CT（6%）。虽然从同一条河流采集的上游和下游全水样品中观察到这些活性中间体的产量只有很小的差异，但不同河流之间的（OM）-O-3* 和O-1（2）产量相差30-50%。O-1（2）的表观量子产率遵循与（OM）-O-3* 相似的趋势，与（OM）-O-3* 作为O-1（2）形成的前体一致。较高的（OM）-O-3* 反应性观察到整个水样品比OM分离物相同的水，这表明差异回收率的光反应性的部分固相萃取。（OM）-O-3* 和O-1（2）产率随着E-2/E-3比率（A（254 nm）除以A（365 nm））的增加而增加，并且随着样品的供电子能力的增加而降低，因此也表现出在参考胡敏酸和富里酸分离物中观察到的趋势。与EfOM和DOM分离物的混合实验表明，EfOM的三重态DOM的淬灭的证据时，实测产量与理论产量进行了比较。总之，结果表明，高达25%（v/v）的污水对河流系统的光化学产生（OM）-O-3* 和O-1（2）的影响可以忽略不计，这显然是因为EfOM对三重态DOM的猝灭。此外，结果突出了整个水研究的重要性，用于量化原位光反应性，特别是（OM）-O-3*。
Effluent organic matter (EfOM), contained in treated municipal wastewater, differs in composition from naturally occurring dissolved organic matter (DOM). The presence of EfOM may thus alter the photochemical production of reactive intermediates in rivers that receive measurable contributions of treated municipal wastewater. Quantum yield coefficients for excited triplet-state OM ((OM)-O-3*) and apparent quantum yields for singlet oxygen (O-1(2)) were measured for both whole water samples and OM isolated by solid phase extraction from whole water samples collected upstream and downstream of municipal wastewater treatment plant discharges in three rivers receiving differing effluent contributions: Hockanum R., CT (22% (v/v) effluent flow), E. Fork Little Miami R., OH (11%), and Pomperaug R., CT (6%). While only small differences in production of these reactive intermediates were observed between upstream and downstream whole water samples collected from the same river, yields of (OM)-O-3* and O-1(2) varied by 30-50% between the rivers. Apparent quantum yields of O-1(2) followed similar trends to those of (OM)-O-3*, consistent with (OM)-O-3* as a precursor to O-1(2) formation. Higher (OM)-O-3* reactivity was observed for whole water samples than for OM isolates of the same water, suggesting differential recoveries of photoreactive moieties by solid phase extraction. (OM)-O-3* and O-1(2) yields increased with increasing E-2/E-3 ratio (A(254 nm) divided by A(365 nm)) and decreased with increasing electron donating capacities of the samples, thus exhibiting trends also observed for reference hurnic and fulvic acid isolates. Mixing experiments with EfOM and DOM isolates showed evidence of quenching of triplet DOM by EfOM when measured yields were compared to theoretical yields. Together, the results suggest that effluent contributions of up to 25% (v/v) to river systems have a negligible influence on photochemical production of (OM)-O-3* and O-1(2) apparently because of quenching of triplet DOM by EfOM. Furthermore, the results highlight the importance of whole water studies for quantifying in situ photoreactivity, particularly for (OM)-O-3*.