Risk estimation and annual fluxes of emerging contaminants from a Scottish priority catchment to the estuary and North Sea.

Emerging contaminants (ECs) such as endocrine-disrupting chemicals (EDCs) and pharmaceuticals and personal care products (PPCPs) attracted global concern during the last decades due to their potential adverse effects on humans and ecosystems. This work is the first study to assess the spatiotemporal changes, annual fluxes and ecological risk of ECs (4 EDCs and 6 PPCPs) by different monitoring strategies (spot and passive sampling) over 12 months in a Scottish priority catchment (River Ugie, Scotland, 335 km2). Overall, the total concentration in water ranged from <LOD to 55.13 ng/l (mean 5.14 ng/l) for EDCs and 0.24 to 361.2 ng/l (mean 51.16 ng/l) for PPCPs, respectively. Ibuprofen and carbamazepine were observed to be the dominant contaminants in the River Ugie. The total annual fluxes of 4 EDCs transported to the Ugie estuary and North Sea were estimated to be 409 and 294 g based on the spot and passive sampling data, respectively, while they were 4636 and 4517 g for 6 PPCPs by spot and passive sampling, respectively. The spatiotemporal trend suggested that human activities and medication usages were the primary source of the contaminants. The overall comparison of the two sampling strategies supported the hypothesis that passive sampling tends to integrate the contaminants over a period of exposure and allows quantification of contamination at low concentration. The ecological risk assessment showed that bisphenol A posed the highest risks with 21.5% of the spot samples, resulting in a risk quotient >1. This suggests that mitigation measures might need to be taken to reduce the input of emerging contaminants into the river and its adjacent estuary and sea.