Generic OH• Scavenging Constants in UV/H2O2 Screening: Size and Direction of the Error Across Four Published Datasets
Year: 2026
Type: preprint
Abstract: Generic literature rate constants are widely used to estimate hydroxyl-radical (OH•) scavenging in UV/H2O2 screening when no matrix-specific probe measurement is available. The reliability of that shortcut is usually assumed rather than tested. Using four independently published datasets, this study compares generic-constant scavenging estimates with experimentally informed references to establish the size and direction of the error. On a common basis, the ratio R of the generic to the reference matrix scavenging rate, generic constants overestimated probe-derived background scavenging in all three waters of Rosenfeldt and Linden (2007), by 2.5- to 11.8-fold. Against a rate-implied reference from Xiao et al. (2015), the generic model overestimated the matrix sink by 1.05- to 1.31-fold in all six conditions (equivalently, it underestimated matrix OH• by the same factor, if primary generation is correctly predicted). In four waters from Katsoyiannis et al. (2011), the sign of the error differed between matrices (R = 0.81–1.26; geometric mean 1.02, interval including unity). A one-parameter sweep shows that the DOM rate constant that reconciles the generic and measured sinks ranges from 1.97 to 3.50 × 104 L (mg C)-1 s-1 across these waters, bracketing the generic value of 2.5 × 104, and neither bulk DOM nor alkalinity ordered the error monotonically. A reconstruction of the steady-state balance against Wu and Linden (2010) reproduces the published direction and hierarchy of the CO3•- contribution. The probe-based method yields very different outcomes in the two datasets that use it, and the other methods are each represented by one dataset, so the contribution of the inference method cannot be separated from that of water and study. The findings argue against a single transferable correction factor and in favor of reporting generic-constant estimates with a matrix-specific uncertainty range.
Source: ChemRxiv
Author: Luciano Guimarães Gomes
Language: English
Subfield: Water Science and Technology
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7223014308