Abstract：
The excited triplet-state of dissolved organic matter (3DOM*) is a major reactive intermediate in sunlit waters. Its quantum yield is important in understanding the fate of organic micropollutants. The degradation efficiency of its chemical probe, 2,4,6-trimeythlphenol (fTMP), is generally used as a proxy of the quantum yield. However, fTMP has been described and modelled only for freshwater systems. Therefore, this study quantified fTMP in inland freshwater and coastal seawater sampled in Japan by conducting steady-state photochemical experiments. Optical properties of water were then used to model fTMP. Results indicated that the inland freshwater DOM originated mainly from terrestrial sources, while the coastal seawater DOM were microbial-dominated. On average, inland freshwater exhibited lower fTMP (61.2 M-1) than coastal seawater (79.7 M-1) and the coastal seawater exhibited significant variations in the proportion of high-energy 3DOM* (> 250 kJ/mol). In addition, E2:E3 (ratio of absorbance at 254 to 365 nm) was positively correlated with fTMP of inland freshwater, coastal seawater, and the overall dataset. Catchment conditions such as forest coverage also influenced the production of 3DOM* and high-energy 3DOM* in inland freshwater. Furthermore, the developed models estimated fTMP based on the optical properties of both freshwater and seawater, providing valuable insights about 3DOM* photochemistry in the aquatic environment.
摘要：
溶解有机物的激发三重态（3DOM*）是阳光照射下的主要反应中间体。它的量子产率对于理解有机微污染物的命运很重要。其化学探针的降解效率，2,4,6-三甲苯酚(fTMP)，通常用作量子产率的代表。然而,fTMP仅针对淡水系统进行了描述和建模。因此,这项研究通过进行稳态光化学实验，对日本内陆淡水和沿海海水中的fTMP进行了定量。然后使用水的光学性质来模拟fTMP。结果表明，内陆淡水DOM主要来源于陆源，而沿海海水DOM以微生物为主。平均而言,内陆淡水的fTMP（61.2M-1）低于沿海海水（79.7M-1），沿海海水的高能3DOM*（>250kJ/mol）的比例存在显着变化。此外,E2:E3(254~365nm处的吸光度比值)与内陆淡水的fTMP呈正相关,沿海海水,和整个数据集。森林覆盖率等集水区条件也影响了内陆淡水中3DOM*和高能3DOM*的生产。此外，开发的模型根据淡水和海水的光学特性估计fTMP，提供有关水生环境中3DOM*光化学的有价值的见解。
