Emerging organic contaminants in groundwater under a rapidly developing city (Patna) in northern India dominated by high concentrations of lifestyle chemicals.

Laura A Richards,Ashok Ghosh,David A Polya,Wayne Civil,Dan J Lapworth,Neha Parashar,Debbie White,Arun Kumar,Sumant Kumar,Rupa Kumari,Daren C Gooddy,Stefan Krause,Chuanhe Lu,Biswajit Chakravorty

doi:10.1016/j.envpol.2020.115765

Abstract

Aquatic pollution from emerging organic contaminants (EOCs) is of key environmental importance in India and globally, particularly due to concerns of antimicrobial resistance, ecotoxicity and drinking water supply vulnerability. Here, using a broad screening approach, we characterize the composition and distribution of EOCs in groundwater in the Gangetic Plain around Patna (Bihar), as an exemplar of a rapidly developing urban area in northern India. A total of 73 EOCs were detected in 51 samples, typically at ng.L-1 to low μg.L-1 concentrations, relating to medical and veterinary, agrochemical, industrial and lifestyle usage. Concentrations were often dominated by the lifestyle chemical and artificial sweetener sucralose. Seventeen identified EOCs are flagged as priority compounds by the European Commission, World Health Organisation and/or World Organisation for Animal Health: namely, herbicides diuron and atrazine; insecticides imidacloprid, thiamethoxam, clothianidin and acetamiprid; the surfactant perfluorooctane sulfonate (and related perfluorobutane sulfonate, perfluorohexane sulfonate, perfluorooctanoic acid and perfluoropentane sulfonate); and medical/veterinary compounds sulfamethoxazole, sulfanilamide, dapson, sulfathiazole, sulfamethazine and diclofenac. The spatial distribution of EOCs varies widely, with concentrations declining with depth, consistent with a strong dominant vertical flow control. Groundwater EOC concentrations in Patna were found to peak within ∼10km distance from the River Ganges, indicating mainly urban inputs with some local pollution hotspots. A heterogeneous relationship between EOCs and population density likely reflects confounding factors including varying input types and controls (e.g. spatial, temporal), wastewater treatment infrastructure and groundwater abstraction. Strong seasonal agreement in EOC concentrations was observed. Co-existence of limited transformation products with associated parent compounds indicate active microbial degradation processes. This study characterizes key controls on the distribution of groundwater EOCs across the urban to rural transition near Patna, as a rapidly developing Indian city, and contributes to the wider understanding of the vulnerability of shallow groundwater to surface-derived contamination in similar environments.

Highlights

A total of 73 emerging organic contaminants (EOCs) were detected within the 51 groundwater samples (Table S1)
It is noteworthy that our results show that even groundwater EOCs, albeit for a limited number of samples and compounds, can be near or in exceedance of Predicted no-effect concentrations (PNECs) or health advisory values, as most of the water samples are known to be used for drinking water and for other domestic purposes
A total of 73 EOCs were detected within the 51 samples, typically at ng.LÀ1 to low mg.LÀ1 level concentrations, and were broadly categorized by dominant usage

Summary

Introduction

Aquatic pollution from legacy and emerging organic contaminants (EOCs) is of increasing attention and concern in India (Lapworth et al, 2018; Philip et al, 2018; Sharma et al, 2019) and globally (Kasprzyk-Horndern et al, 2008; Kim et al, 2016; Lapworth et al, 2012, 2015a; Loos et al, 2013; Pal et al, 2010; Sorensen et al, 2015; White et al, 2019). Numerous sources can contribute to aqueous EOCs, including raw or treated wastewater discharge (Kasprzyk-Horndern et al, 2008; Writer et al, 2013), run-off from agricultural, farming and livestock activities (Lapworth et al, 2012; Lupo et al, 2012), industrial processes (Lübbert et al, 2017), urban drainage (You et al, 2015) and spills (Gavrilescu et al, 2015). EOCs have been used to trace the fate and transport of pollutants in aqueous systems (Glassmeyer et al, 2005; James et al, 2016; White et al, 2019) including to determine groundwater vulnerability in northern India (Lapworth et al, 2018). In particular, has been used as a reliable wastewater tracer (Loos et al, 2013; Oppenheimer et al, 2011; Scheurer et al, 2009; White et al, 2019; Yang et al, 2017) due to environmental persistence (Batchu et al, 2013), lack of bioaccumulation (Roberts et al, 2000), minimal degradation during wastewater treatment (Scheurer et al, 2009; Torres et al, 2011) and widespread occurrence (Batchu et al, 2013; Loos et al, 2013)

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