Eco-friendly utilization of fishery waste for sustainable heavy metal stabilization in mine-impacted agricultural soil

초록

Agricultural soils near mines can be contaminated with As and heavy metals (Pb and Zn) posing serious health risks to animals and humans through bioaccumulation. This study aimed to evaluate the effectiveness of oyster shells (OS) and mussel shells (MS) as stabilizers for the contaminated soil. The shells were processed in three forms: natural oyster/mussel shells -#10 mesh to + #20 mesh (NOS10/NMS10); natural oyster/mussel shells -#20 mesh to + #40 mesh (NOS20/NMS20); and calcined oyster/mussel shells -#10 mesh to + #20 mesh (COS10/CMS10). The stabilizing agents were mixed with contaminated soil at dosages ranging from 2 to 10 wt% and wet-cured for four weeks to evaluate their stabilization effectiveness. Following the treatments, effectiveness was assessed using the 0.1 M HCl extraction method. To assess crop-cultivation safety, lettuce was grown for one month in both untreated and treated soils. The stabilization treatment results showed that the stabilization efficiencies for As, Pb, and Zn followed the order: COS10 > CMS10 > NOS20 > NOS10 > NMS20 > NMS10. Lettuce cultivated in stabilized pots exhibited greater weight and length compared to those grown in contaminated pots. Following stabilization, Pb levels in plant tissues were undetectable, and Zn levels were considerably reduced. Results from SEM-EDX and elemental mapping analyses indicated that As was predominantly stabilized through Ca-As precipitation, whereas Pb and Zn were incorporated into the pozzolanic-phase reaction products. This study demonstrates that recycled oyster and mussel shells can be effectively utilized as stabilizing agents for remediating heavy metal-contaminated soils and ensuring safe crop cultivation.

키워드