Excited triplet states of dissolved organic matter (³DOM) are quantified directly with the species-specific probes trans,trans-hexadienoic acid (HDA) and 2,4,6-trimethylphenol (TMP), and indirectly with the singlet oxygen (¹O₂) probe furfuryl alcohol (FFA). Although previous work suggests that these probe compounds may be sensitive to solution conditions, including dissolved organic carbon concentration ([DOC]) and pH, and may quantify different ³DOM subpopulations, the probes have not been systematically compared. Therefore, we quantify the apparent photoreactivity of diverse environmental waters using HDA, TMP, and FFA. By conducting experiments under ambient [DOC] and pH, with standardized [DOC] and pH, and with solid phase extraction isolates, we demonstrate that much of the apparent dissimilarity in photochemical measurements is attributable to solution conditions, rather than intrinsic differences in ³DOM production. In general, apparent quantum yields (Φ_¹O2 ≥ Φ_³DOM,TMP ≫ Φ_³DOM,HDA) and pseudo-steady state concentrations ([¹O₂]_ss > [³DOM]_ss,TMP > [³DOM]_ss,HDA) show consistent relationships in all waters under standardized conditions. However, intrinsic differences in ³DOM photoreactivity are apparent between DOM from diverse sources, as seen in the higher Φ_¹O2 and lower Φ_³DOM,TMP of wastewater effluents compared with oligotrophic lakes. Additionally, while conflicting trends in photoreactivity are observed under ambient conditions, all probes observe quantum yields increasing from surface wetlands to terrestrially influenced waters to oligotrophic lakes under standardized conditions. This work elucidates how probe selection and solution conditions influence the apparent photoreactivity of environmental waters and confirms that ³DOM or ¹O₂ probes cannot be used interchangeably in waters that vary in [DOC], pH, or DOM source.

中文翻译：

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探针选择和溶液条件对溶解有机物表观光反应性的影响

溶解态有机物的激发三重态（³ DOM）可直接用物种特异性探针反式，反己二酸（HDA）和2,4,6-三甲基苯酚（TMP）定量，而间接利用单线态氧（¹ O ₂）探测糠醇（FFA）。尽管先前的工作表明这些探针化合物可能对溶液条件敏感，包括溶解的有机碳浓度（[DOC]）和pH值，并且可以量化不同的³DOM亚群，探针尚未得到系统地比较。因此，我们使用HDA，TMP和FFA量化了各种环境水的表观光反应性。通过在环境[DOC]和pH值，标准化[DOC]和pH值以及固相萃取分离物下进行实验，我们证明了光化学测量中的许多明显差异可归因于溶液条件，而不是³ DOM中的内在差异生产。通常，表观量子产率（Φ _{¹ Ò 2} ≥ Φ _{³ DOM，TMP} » Φ _{³ DOM，HDA}）和伪稳态浓度（[ ¹ Ò ₂ ]_ss > [ ³ DOM] _ss，TMP > [ ³ DOM] _ss，HDA）在标准化条件下在所有水域中显示出一致的关系。然而，在本征的差异³ DOM光反应DOM之间是显而易见的来自不同源的，如在较高的可见Φ _{¹ Ò 2}和降低Φ _{³ DOM，TMP}与贫营养湖泊相比的废水排放量 此外，虽然在环境条件下观察到光反应性的相互矛盾的趋势，但所有探针均观察到在标准条件下量子产率从表面湿地到受地雷影响的水域再到贫营养化湖泊。这项工作阐明了探针的选择和溶液条件如何影响环境水的表观光反应性，并证实了^3种DOM或¹ O ₂探针在[DOC]，pH或DOM来源不同的水中不能互换使用。