Profiling of Antibiotic Residues in Soil and Vegetables Irrigated Using Pharmaceutical-Contaminated Water in the Delhi Stretch of the Yamuna River, India

The movement of emerging pollutants, particularly antibiotics, from surface water to crops through the process of plant uptake poses a significant public concern related to the agricultural utilization of untreated water and biosolids. It is essential to consider the potential risk of inadvertent human exposure and the accumulation of drug residues in fresh food crops, particularly in the case of various green vegetables. Nowadays, environmental research is mainly focusing on the bioaccumulation and threat posed by pharmaceutical residues, especially antibiotics and personal care products in the soil–plant ecosystem. In the present study, the concentration of pharmaceuticals in soil samples collected from agricultural fields irrigated with Yamuna water were evaluated using suitable extraction and sophisticated instrumentation techniques. Out of the five sampling locations, the highest concentration of ofloxacin was reported at Site-V (0.265 µg/mg) during the premonsoon period and the lowest concentration (0.014 µg/mg) during the postmonsoon at Site-II, in terms of the average concentration; this could be due to the combined effect of anthropogenic activities, surface water runoff, and the combined load of drains in the vicinity. For the quantification of the selected antibiotics in a green leafy vegetable (Spinach oleracea), the concentration of ofloxacin was found to be the highest at Okhla barrage Site-V (5.586 µg/mg) during the premonsoon period, with the lowest concentration observed at Site-I, from 1.382 µg/mg to 1.698 µg/mg, during the postmonsoon period. The higher concentration of ofloxacin in crops is because of its susceptibility to being absorbed at the soil’s surface. Plant absorption of antibiotics is influenced primarily by the biological characteristics of the plant, encompassing factors like the lipid and carbohydrate composition of the plant roots. Additionally, the physiochemical properties of the drugs, including molecular size, Kow, and pKa, play a significant role in this process. The antibiotics showed greater variation in their concentration during the premonsoon than in the postmonsoon period, which may be because of precipitation, dilution, and the leaching effect of the soil. For all three of the drugs studied, the concentrations followed the order of ofloxacin > amoxicillin > erythromycin. Thus, the effective management of contaminated soils and vegetables must consider continuous monitoring and risk assessment of high-priority antibiotics to prevent negative effects on the natural environment and human health.