FATE OF TRACE CONTAMINANTS IN RIVERS

Abstract

Environmental matrices are repositories of thousands of trace contaminants (TCs) released along with treated/untreated wastewater. Despite extensive research on the detection of TCs in surface water, other environmental compartments such as sediments and groundwater are yet to be thoroughly investigated. The escalating usage of pharmaceuticals and personal care products (PPCPs) presents a grim situation for populous countries such as India. The distribution and fate of TCs in the environmental matrices is still unclear due to lack of comprehensive studies. River Yamuna is one of the primary rivers, crossing the highly populated and industrial parts of Northern India before merging with the Ganges. To assess the heavy anthropogenic impact on the Yamuna River basin with respect to occurrence of TCs, samples comprising of surface water, sediment, groundwater, and aquatic flora were collected from the upstream and downstream of densely populated cities and towns situated along the heavily contaminated river. Liquid chromatography tandem mass-spectroscopy was used to quantify 16 widely known PPCPs and hormones in the environmental samples. The acquired chromatographic data was analyzed via target and suspect screening approaches. The analysis of seasonal surface water samples (summer, post-monsoon, and winter) exhibited high concentrations of antibiotics and hormones. The groundwater samples collected from shallow drinking water wells of the catchment also showed consistent presence of hormones at high concentrations. The study analyzed the potential health hazards posed by the quantified TCs in the groundwater by using risk quotient approach. Similar to surface water and groundwater, sediment samples also highlighted the continuous occurrence of hormones at almost all the collection points. To evaluate further, the surface water and groundwater samples were subjected to high resolution mass spectrometry (HRMS) screening against a library of 2302 TCs resulting in a list of 450 TCs in the surface water and 309 TCs in the groundwater. The HRMS screening highlighted the abundance of agricultural chemicals and pharmaceuticals many which are rarely reported in the published literature. Apart from occurrence of parent TCs, batch studies related to trimethoprim and progesterone showed their degradation patterns in the surface water and sediment due to biotic and abiotic forces.