Soil and groundwater are connected compartments, yet the extensive use of tetracycline antibiotics (TCs) in livestock, medical, and agricultural systems has created persistent contamination within the soil–groundwater continuum. This review focuses on tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC), doxycycline (DOX), and related derivatives, and synthesizes how pH, inorganic ligands, dissolved/soil organic matter, oxygen availability, salinity, hydrogeological conditions, minerals, and biotic communities jointly govern adsorption–desorption, leaching–transport, biodegradation, abiotic transformation, and antibiotic-resistance-gene (ARG)-related risks. Unlike monitoring-oriented summaries, this review distinguishes single-factor controls from coupled controls across compartments. The available evidence suggests that pH and mineral/organic interfaces mainly determine initial retention, whereas hydrological connectivity, dissolved organic matter quality, redox status, and microbial–enzymatic activity determine whether retained TCs are immobilized, transformed, remobilized, or converted into persistent transformation products. Importantly, multi-factor interactions are not uniformly synergistic: humic/aromatic organic matter may enhance sorption, whereas proteinaceous or microbial-derived dissolved organic matter (DOM) can promote mobility through site competition; salinity may suppress sorption through cation competition while simultaneously restructuring microbial degradation pathways; and oxygen-rich conditions can accelerate degradation but also alter Fe/Mn oxide formation and secondary adsorption. Remaining uncertainties include non-comparable adsorption metrics, environmentally unrealistic ion concentrations in some batch studies, insufficient in situ groundwater evidence, and weak linkage between transformation products and ARG dissemination. Finally, process-based multi-factor models, in situ dynamic monitoring, and cross-compartment validation are proposed as priorities for risk assessment and remediation of TCs in soil–groundwater systems.
Dong et al. (Fri,) studied this question.