From source to stream: CEC source identification and quantification in the Changle River Watershed.

Area of Science:

• Environmental Chemistry
• Water Quality Assessment
• Ecotoxicology

Background:

• Contaminants of emerging concern (CECs), such as pharmaceuticals, personal care products (PPCPs), and endocrine-disrupting chemicals (EDCs), pose ecological risks in freshwater systems.
• The spatial distribution and origins of CECs in river networks are not well understood, hindering effective management.

Purpose of the Study:

• To investigate the spatial characteristics and source contributions of CECs in the Changle River watershed.
• To develop and apply an integrated framework for CEC source apportionment.

Main Methods:

• Coupling of spatial statistics, multivariate statistical analyses, and a receptor model.
• Analysis of CEC concentrations in river water across different seasons (wet and dry).
• Identification of pollution hotspots and primary pollutant sources.

Main Results:

• Widespread CEC contamination was observed in both the main channel and tributaries, with higher concentrations in the dry season.
• Untreated sewage (37.6%) and swine wastewater (39.5%) were identified as the dominant sources of CECs.
• Wastewater treatment plant (WWTP) effluents contributed minimally (9.77%) to the overall CEC load.

Conclusions:

• CEC contamination in the Changle River is driven by a complex mix of point and non-point sources, with significant contributions from untreated domestic and agricultural wastewater.
• Effective watershed management requires targeted source control strategies to mitigate ecological and human health risks associated with CECs.