Nontarget Analysis and Ecological Risk Assessment of Contaminants of Emerging Concern in the Riverine Environment of the Delhi Region

Nontarget analysis (NTA) has emerged as a powerful tool for screening contaminants of emerging concern (CECs) in water matrices using high-resolution mass spectrometry (HRMS). This study detected more than 24000 molecular features and identified 658 CECs belonging to various categories, including pharmaceuticals (50.5%), pesticides (24.6%), industrial chemicals (13.2%), personal care products (6.5%), hormones (4.3%), and artificial sweeteners (0.9%) across four anthropogenically influenced sites along the River Yamuna flowing through the capital city of India. At Schymanski confidence level 2, 48 CECs were confirmed using internal and external standard libraries through MS/MS spectral matching. Pharmaceuticals were detected in the range of 40–9400 ng/L, pesticides in the range of 27–10480 ng/L, and artificial sweeteners in the range of 121–245 ng/L. Metazachlor exhibited high risk quotient (RQ > 250) values implying possible high risk to aquatic life. This study represents one of the first systematic NTA investigations of the River Yamuna, with several CECs identified for the first time in the New Delhi stretch. The findings provide novel insights into the fingerprint of CECs in the river, which could be useful in implementing targeted strategies to control the pollution, thereby balancing environment protection and regional development.