Sorbent- and sorbate-influenced sorption variability and nonlinearity: a meta-analysis on chlorpyrifos with soils, sediments, and other carbonaceous materials
Journal
Water Research X
Journal Volume
30
Start Page
100492
ISSN
25899147
Date Issued
2026-01-01
Author(s)
Ho, Song-Yan
Abstract
Inter-sample sorption variability and nonlinearity can ambiguate fate and ecotoxicity assessment of organic pollutants and remediation strategy. Nonlinear sorption models that assume constancy in organic carbon (OC) normalized sorption coefficient (KOC) are often adopted across different sorbents. This study explored sorbent-side influence on sorption through meta-analysis and modeling of sorption data on chlorpyrifos, a recently Stockholm Convention enlisted non-ionizable organophosphate pesticide, and its main metabolite 3,5,6-trichloropyridinol (TCP). LogKOC varies by approximately 2 log units among soils and sediments. In predicting sorption with natural geosorbents (n = 519), linear-OC and Freundlich models are outperformed by models considering nonlinear sorbate-side (concentration) and sorbent-side (OC content) effects (S=KOCfOCaCb or KOCfOCϕaCb). All nonlinear chlorpyrifos models are C-linear but fOC-nonlinear. The resulting models predict fairly against out-of-domain (untrained) sorbents including biosolids, peat, dissolved organic matter (DOM), biochar, vegetative residues, and wood pieces with root mean squared error (RMSE) ranging from 0.17 to 0.72 (n = 304), hinting the possibility of a universal sorption model across different carbonaceous sorbents. These models capture sorbate competition and sorbent configuration, and may apply or adapt to other chemicals and carbonaceous sorbents to accommodate changing sorbent configurations, compositions, or volume/domain accessibility. Metaphysically, the proposed nonlinear models are grounded in a reference-adjustment framework, where overall effects are quantified as adjustments relative to a base-case scenario, as in thermodynamics and kinetics. Overall, results challenge KOC constancy that underlies most current models while demonstrating the importance of inter-sorbent variations in composition and configuration of organic components for accurate sorption assessment.
Subjects
Nonlinearity
Organic amendment
Sediment
Soil
Sorbent configuration
Sorption
Publisher
Elsevier Ltd
Type
journal article