Emerging contaminants in surface and groundwater of an intensive agro-industrial region: Distribution, risks, and sources assessment

Intensive cultivation and industrial activities pose significant risks to water security from emerging contaminants (ECs). This study monitored pesticides, polycyclic aromatic hydrocarbons (PAHs), and phthalates (PAEs) to assess spatial distribution, ecological and human health risks and source assessment in the surface and groundwater of Hindon River Basin, India. The leaching potential of currently used pesticides was also assessed using pesticide physicochemical and region hydrogeological properties. Notably, detected ECs are associated with (partially) treated wastewater discharge from intensive agriculture and industrial activities, polluted rivers, frequent flooding and declining groundwater levels. The leaching indices indicated that chlorpyrifos, imidacloprid, atrazine, carbendazim, and dimethoate pesticides posed the highest leaching risks due to their widespread application in sugarcane, rice and wheat systems with intense irrigation and shallow groundwater level (∼9 mbgl). The pyrene, anthracene, di-n-butyl phthalate (DnBP), diisobutyl phthalate (DiBP) and di-cyclohexyl phthalate (DCHP) posed moderate-high ecological risks, especially to aquatic organisms such as algae, daphnia, and fish. Health risk assessment identified DiBP and DnBP as the most critical contaminants, with ingestion posing the highest risk. The source apportionment analysis identified five major sources with industrial and commercial chemical applications and related wastewater discharges found as dominant. The presence of PAEs was linked to textile-dyeing, paper and pulp, plastic molding, and widespread use of plasticizers, adhesives and coatings in the chemical industries. In contrast, PAHs presence reflected fossil fuel combustion, brick kiln operations, crop residues open burning, and vehicular traffic. The study findings will help in developing source-specific remediation strategies, safeguarding public and ecological health, identifying potential recharge locations and developing a regulatory framework.