Enhancing Cleanup of Heavy Metal Polluted Landfill Soils and Improving Soil Microbial Activity Using Green Technology with Ferrous Sulfate

Gilbert C. Sigua; Arnel Celestino; Annie Melinda Paz-Alberto; Kenneth C. Stone; Ronaldo T. Alberto
Landfills have led to some of the most intense battles over pollution that has ever been seen. With the population skyrocketing worldwide, these landfills will only become more of a public issue as time goes on. Heavy metals from several sources especially in landfills are an increasingly urgent problem because of its contribution to environmental deterioration and intensive degradation of soil microbial biodiversity. Despite the arguments over landfills in general, few or no effort was undertaken to clean up contamination of heavy metals in abandoned landfills. In our study new methods were proposed using a green technology or phytoremediation with ferrous sulfate in enhancing cleanup of heavy metal polluted landfill soils. Composite soil samples were collected near an open abandoned dump site in Cabanatuan City, Nueva Ecija, Philippines. Three rates of sulfur: 0, 40 and 80 mmol kg-1 as ferrous sulfate (26% S) was thoroughly mixed with the soil. Four healthy seedlings of mustard (Brassica juncea, L) were transplanted to each pot. Soil pH showed a decreasing trend for soils treated with 0 and 80 mmol kg-1 of sulfur (S) after 15 days (8.12 to 7.38) and after 25 days (8.56 to 7.78). Application of ferrous sulfate significantly enhanced microbial activities in contaminated soils. Average respiration rate in soil with 0 mmol kg-1 S was about 2.0 mg kg-1 CO2-C compared with 19.0 mg kg-1 CO2-C for soils amended with 80 mmol S kg-1. Although dry matter yield and uptake of heavy metals by mustard were somewhat variable with S application, solubility of copper (Cu), zinc (Zn) and manganese (Mn) in soils was significantly (p≤0.001) increased with S application. Our study has demonstrated the beneficial outcome of green technology in combination with ferrous sulfate in cleaning up heavy metals contamination in landfills and at the same time improving soil microbial biomass following phytoremediation.
Landfills; Heavy Metals; Mustard; Ferrous Sulfate; Phytoremediation; Solubility; pH
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