249-5 Fate and transport of emerging organic contaminants (EOCs) at the soil-water interface: Pathways to subsurface contamination in agricultural soil

Session: Emerging Contaminants: Geochemical Insights and Impacts on Human and Environmental Health

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Emerging organic contaminants (EOCs) can be introduced into agricultural soils through various pathways, including irrigation water, biosolids, and floodwater. Upon introduction, these contaminants may travel through the soil profile and eventually reach the underlying groundwater. This study examined the transport and mobility of three frequently reported EOCs—carbamazepine (CAR), sulfamethoxazole (SMX), and caffeine (CAF)—in soil samples obtained from a paddy field. Laboratory column tests were performed under saturated conditions utilizing both individual and combined contaminant treatments. The soil was identified as loamy sand, with 0.64% organic carbon and 81.2% sand. Sodium chloride, which was employed as a conservative tracer, attained the half-breakthrough point (C/C_₀=0.5) after 5.5 hours. In sterile soil, the half-breakthrough point for individual pollutants was attained at 7, 12, and 26 hours for CAF, SMX, and CAR, respectively. Contaminant mixtures further extended the durations to 18, 20, and 31 hours, respectively. The recovery of EOCs from the column effluent in sterile soil occurred in the sequence of CAF > SMX > CAR, but in non-sterile soil, the sequence was CAR > SMX > CAF. The findings indicate that the mobility of EOCs in soil is influenced by the physicochemical characteristics of both the pollutants and the soil, as well as the presence of co-occurring contaminants and the activity of soil microorganisms.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-5402

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