Transport Mechanisms of the Anthropogenic Contaminant Sulfamethoxazole in Volcanic Ash Soils Evaluated Using the Hydrus-1d Model
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Date
2024
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Abstract
The volcanic soils in Chile, where a significant portion of agricultural activities take place, are impacted by the presence of veterinary drugs, including sulfamethoxazole (SMX). The transport of SMX in soils Collipulli (CLL), Frutillar (FRU), Nueva Braunau (NBR), and Osorno (OSR) was explored. Aadsorption batch, kinetics, and column breakthrough curve (BTC) experiments were conducted, alongside transport modelling. The adsorption kinetics of SMX in CLL soil followed a pseudo-first-order (PPO) model, while FRU, NBR, and OSR soils aligned with a pseudo-second-order (PSO) model. Freundlich isotherms effectively described SMX adsorption in CLL and OSR soils, indicating multilayer adsorption, while Langmuir isotherms fit the FRU and NBR soils, suggesting monolayer adsorption. Using HYDRUS-1D software, we simulated SMX transport in soil columns. BTCs were best modelled using a two-site sorption model with both equilibrium and kinetic adsorption. SMX was more mobile in CLL soil, due to its lower organic matter (OM) content and adsorption capacity, while FRU, NBR, and OSR soils showed slower transport, reflecting higher OM content and greater adsorption capacity, reducing SMX leaching. These findings emphasize the importance of soil properties, such as OM content, in influencing SMX behavior, and are vital for assessing environmental impacts and developing mitigation strategies.
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Keywords
Fate and transport, Column breakthrough curves, Volcanic soils, Antibiotic pollution, Hydrus -1D model