Comparing black carbon types in sequestering polybrominated diphenyl ethers (PBDEs) in sediments

Area of Science:

• Environmental Chemistry
• Environmental Science
• Sediment Contamination

Background:

• Polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants found widely in aquatic sediments.
• PBDEs exhibit a strong affinity for black carbon (BC), influencing their environmental fate and bioavailability.
• BC amendment in sediments is explored as a strategy to reduce PBDE bioavailability.

Purpose of the Study:

• To quantify the freely dissolved concentration (Cfree) of PBDEs in BC-amended sediments.
• To compare the sequestration efficacy of different BC materials (biochar, charcoal, activated carbon) for PBDEs.
• To assess the influence of sediment organic carbon (OC) content on PBDE sequestration by BC.

Main Methods:

• Matrix solid-phase microextraction (SPME) was employed to measure Cfree of PBDEs.
• Three types of BC—biochar, charcoal, and activated carbon—were evaluated as amendments.
• Experiments were conducted using sediments with varying organic carbon content (0.12% and 0.87%).

Main Results:

• Activated carbon demonstrated superior sequestration capacity for PBDEs compared to biochar and charcoal.
• At a 1% amendment rate in low OC sediment, activated carbon reduced PBDE Cfree by 94.1-98.3%.
• PBDE sequestration was less effective in high OC sediments, indicating a reduced impact of BC amendment.

Conclusions:

• The effectiveness of BC-based remediation for PBDEs is highly dependent on the BC material properties and the characteristics of the contaminated sediment.
• Activated carbon shows significant potential for reducing PBDE bioavailability in sediments.
• Careful consideration of BC type and sediment OC content is crucial for successful BC-based environmental mitigation strategies.