[Distribution Characteristics and Risk Assessment of 209 Polychlorinated Biphenyls in Dongting Lake and the Inflow...

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Water Quality Assessment

Background:

• Polychlorinated biphenyls (PCBs) are persistent organic pollutants with potential ecological impacts.
• Dongting Lake is a significant aquatic ecosystem requiring assessment of PCB contamination.

Purpose of the Study:

• To quantify PCB congeners in Dongting Lake surface water and inflow rivers.
• To identify major PCB congeners and their sources.
• To evaluate the ecological toxicity risk posed by PCBs.

Main Methods:

• Quantitative analysis of 209 PCB congeners using isotope-dilution high-resolution mass spectrometry.
• Sampling across 21 sites in Dongting Lake and its inflow rivers.
• Ecological toxicity risk assessment using the toxicity equivalent factor (TEF) method.

Main Results:

• 50 PCB congeners were detected, with total PCB concentrations ranging from 0.077 to 10 ng·L⁻¹, averaging 2.7 ng·L⁻¹.
• PCB contamination was highest in inflow rivers, followed by the lake region, and lowest at the outlet.
• PCB11 was the predominant congener (59% of total PCBs), linked to organic pigment production; atmospheric deposition and historical residues were identified as main sources.
• Ecological toxicity (TEQ) was significantly below standard limits, indicating no harm to exposed organisms.

Conclusions:

• PCB pollution in Dongting Lake is at a low level compared to global studies.
• Unintentional emissions from organic pigment production are a key source of PCB11.
• The current level of PCB contamination in Dongting Lake's surface water does not pose an ecological risk.