The occurrence and persistence of surface water contaminants across different landscapes

Abstract

Surface water contaminants, including both conventional contaminants (e.g., nutrients, trace elements) and emerging contaminants (e.g., pesticides, pharmaceuticals) are heavily influenced by urban and rural land use practices. The goal of the study was to characterize the influence of watershed land use practices on surface water quality. Specific objectives were to (1) identify and quantify the type and concentration of nutrients, trace elements, pesticides, pharmaceuticals and personal care products in four watersheds and (2) understand potential sources of contamination based on the watershed's land cover and land use characteristics (i.e., oil and gas, urban, mining, agriculture). Monthly polar organic chemical integrative samples and water grab samples were collected from March-October 2022. The results showed that surface water quality varied by location, season, and flood condition Specifically, aluminum (mean = 758 μg L^-1) and iron (mean = 1130 μg L^-1) exceeded chronic aquatic life water quality criteria in the agricultural watershed, while imidacloprid exceeded the chronic criteria limit for freshwater invertebrates in both the urban (mean = 5.96 ng L^-1) and agricultural (mean = 4.72 ng L^-1) watersheds. Sulfate concentrations (mean = 666 mg L^-1) also exceeded ambient water quality criteria in the watershed with a high activity of mining. This study provides important steps for developing a comprehensive understanding of land use impacts on contaminant presence and concentration in surface waters, improved understanding of the implications to non-target species, and necessary water treatment processes to ensure a safe water supply.

Keywords: Contaminants of emerging concern; Ecotoxicity; Non-point source pollution; Pesticides; Pharmaceuticals and personal care products; Water quality.