Singlet Oxygen Quantum Yields in Environmental Waters

Abstract

Singlet oxygen (1O2) is a reactive oxygen species produced in sunlit waters via energy transfer from the triplet states of natural sensitizers. There has been an increasing interest in measuring apparent 1O2 quantum yields (ΦΔ) of aquatic and atmospheric organic matter samples, driven in part by the fact that this parameter can be used for environmental fate modeling of organic contaminants and to advance our understanding of dissolved organic matter photophysics. However, the lack of reproducibility across research groups and publications remains a challenge that significantly limits the usability of literature data. In the first part of this review, we critically evaluate the experimental techniques that have been used to determine ΦΔ values of natural organic matter, we identify and quantify sources of errors that potentially explain the large variability in the literature, and we provide general experimental recommendations for future studies. In the second part, we provide a qualitative overview of known ΦΔ trends as a function of organic matter type, isolation and extraction procedures, bulk water chemistry parameters, molecular and spectroscopic organic matter features, chemical treatments, wavelength, season, and location. This review is supplemented with a comprehensive database of ΦΔ values of environmental samples.

Photochemical interactions between pesticides and plant volatiles

“…Pesticides are generally photodegraded when they absorb solar light (Burrows et al, 2002, Mathon et al, 2021 or when they are irradiated in the presence of natural chromophoric species acting as sensitizers (natural organic matter) or photoinducers (nitrate ions, ferric species…) (Remucal, 2014, Ossola et al, 2021, Marussi and Vione, 2021, Brand et al, 1998. Photochemical reactions between two pesticides can also take place.…”

Factors affecting the mixed-layer concentrations of singlet oxygen in sunlit lakes

“…The range of Φ Δ values obtained from the literature were 0.21–2.89% for SRNOM ( n = 15) and 1.14–5.29% for PLFA ( n = 10). 17 These literature values were measured using a solar simulator or xenon lamp to represent solar irradiance. [ 1 O 2 ] epi,avg SS values were calculated from the single values for Φ Δ , and were compared to [ 1 O 2 ] epi,avg SS values calculated using biexponential models of wavelength-dependent Φ Δ data for SRNOM and PLFA (Fig.…”

“…The difference between Φ Δ values determined using steady-state photolysis and the reference Φ Δ values from Partanen et al for each of the samples closely tracks the difference between experimentally measured and calculated [ 1 O 2 ] SS values, indicating that this parameter is the source of much of the variability. There are many potential sources of error when measuring Φ Δ values, 55 and it is likely experimental error that leads to the difference between experimentally measured Φ Δ values and reference Φ Δ values in this analysis, rather than an incorrect [ 1 O 2 ] SS estimation framework. Overall, our approach estimates [ 1 O 2 ] SS values that are in good agreement with experimentally measured [ 1 O 2 ] SS values for the test-tube case.…”

“… 13–16 Singlet oxygen quantum yield measurements require accurate characterization of the incident light, making these results independent of the light source when performed correctly. 17 In contrast, measurements of [ 1 O 2 ] SS do not require light source characterization, so values reported by different researchers or at different times may not be comparable. Additionally, laboratory measurement conditions are not generally representative of conditions in the environment.…”

US SOLAS Science Report

“…Photochemical and biological processes create reactive oxygen species (ROS; O2-, 1O2, HOOH, OH radical) in seawater and in ice (Powers and Miller, 2015;Diaz et al, 2013;Ossola et al, 2021;Kieber et al, 2003). Organic radicals are produced as well, and together, these radicals will alter redox reaction pathways on time scales controlled by changing solar irradiance, photon absorption, and ecological/ biological function.…”