Polychlorinated biphenyl release from resuspended Hudson River sediment

Area of Science:

• Environmental Chemistry
• Sedimentology
• Contaminant Hydrogeology

Background:

• Polychlorinated biphenyls (PCBs) are persistent organic pollutants found in sediments.
• Sediment resuspension events can release PCBs into the water column, impacting aquatic ecosystems.
• Understanding PCB release dynamics is crucial for effective environmental remediation strategies.

Purpose of the Study:

• To quantify PCB release from resuspended Hudson River sediment.
• To investigate the influence of sediment consolidation time on PCB lability and release.
• To determine the recharge rate of labile PCBs during sediment settling.

Main Methods:

• Utilized three Shear Turbulence Resuspension Mesocosms (STORM tanks) to simulate sediment resuspension.
• Measured PCB desorption and dissolved concentrations over time.
• Varied sediment consolidation (quiescent) periods between resuspension events.
• Analyzed changes in particulate and dissolved PCB concentrations and calculated steady-state Koc values.

Main Results:

• Twenty-two percent of PCBs desorbed within 2 hours of resuspension.
• Approximately 35% of PCBs were in the dissolved phase at steady state.
• Particulate PCB concentrations remained constant across resuspension events.
• Longer consolidation times (4 days) led to a significant decrease in dissolved pentachlorinated PCBs, indicating recharge of the labile pool.

Conclusions:

• Sediment resuspension releases significant amounts of PCBs into the water column.
• The labile pool of PCBs can be recharged during sediment consolidation.
• Sufficient quiescent time between resuspension events enhances the removal of easily desorbable PCBs.
• Findings have implications for managing PCB-contaminated sediments and predicting contaminant fate.