Bioremediation trial on aged PCB-polluted soils--a bench study in Iceland

Area of Science:

• Environmental Science
• Soil Science
• Bioremediation

Background:

• Polychlorinated biphenyls (PCBs) are persistent environmental pollutants with high adsorption to soil organic matter, low water solubility, and toxicity.
• Limited research exists on PCB contamination and degradation in Icelandic soils.
• PCBs bioaccumulate in soil fauna, posing ecological risks.

Purpose of the Study:

• To assess the bioavailability of aged PCBs in Icelandic soils.
• To identify optimal biostimulation methods for PCB pollution reduction.
• To evaluate the effectiveness of different additives, temperatures, and oxygen levels.

Main Methods:

• Assessed PCB bioavailability using earthworms (Eisenia foetida).
• Tested biostimulation additives: N fertilizer, white clover, and pine needles.
• Incubated soil samples under aerobic and anaerobic conditions at 10 °C and 30 °C.
• Analyzed PCB degradation and detected the bphA gene.

Main Results:

• PCBs were bioavailable to earthworms, with lower chlorinated congeners showing higher bioaccumulation.
• Biostimulation with pine needles at 10 °C under aerobic conditions achieved nearly 38% total PCB degradation in 2 months.
• The presence of the aerobic PCB-degrading bphA gene indicates indigenous degradation potential.

Conclusions:

• Aged PCBs are bioavailable to soil fauna in Icelandic soils.
• Pine needle biostimulation under aerobic conditions at 10 °C is a promising method for PCB remediation in cold environments.
• Further field-scale trials are recommended to optimize this bioremediation strategy.