Abstract:
The application of municipal sludge to farmland is a disposal method of sludge recycling, which can improve soil properties and promote crop growth, but also causes exposure risks of pollutants such as polychlorinated biphenyls (PCBs) in farmland. As a kind of persistent organic pollutants, PCBs are absorbed and accumulated in crops and bring potential exposure risks to human health through the food chain. Based on soil pot experiments with different sludge application quantity, sludge types, and plant types, the municipal sludge in Guanzhong area was taken as the research object to explore plant uptake and translocation characteristics of PCBs in soil applied with sludge. The results showed that: the application of municipal sludge in Guanzhong area led to PCBs pollution in soil and plant. After plant harvest, soil, plant roots, and above-ground parts were dominated by low-chlorinated PCBs with the total percent contents increased sequentially, and ∑PCBs in soil was degraded 20.00 %–79.30 %. Plant roots absorbed PCBs in soil and transmitted them to the above-ground part of plants. The uptake and translocation capacities of plants were related to sludge application quantity, sludge types, and plant types. Double sludge application quantity weakened the uptake of ∑PCBs, mono-PCBs–tetra-PCBs, and hexa-PCBs by plant roots. The uptake capacity of plant roots treated with the sludge of Longmen town, Hancheng city, China (sludge of the lowest organic matter content) to ∑PCBs was the highest. The uptake capacity of wheat to ∑PCBs and PCBs homologous in polluted soil was stronger than that of maize, while the translocation capacity was weak. The study provides scientific basis for the risk assessment of sludge agricultural application, the environmental behavior of PCBs in sludge application soil and the phytoremediation of PCBs contaminated soil.