PEAT-ASSISTED PHYTOREMEDIATION OF WASTE FOUNDRY SANDS: PLANT GROWTH, METAL ACCUMULATION AND FERTILITY ASPECTS

We investigated the potential of peat additions to improve plant growth and fertility and to reduce plant metal uptake in waste foundry sands (WFS) landfills. The WFS contains 78211 mg kg⁻¹ and 371 mg kg⁻¹ concentrations of Cr and Ni, respectively, and varied metal concentrations. The experiment investigated the growth of Brassica juncea plants on fertilized WFS mixed with peat at concentrations of 0, 2.5, 5, and 10% (w/w). The highest peat treatment allowed substantial plant growth and increased Ni mass in shoots, which was positively correlated to shoot biomass increments. On a concentration basis, peat additions did not increase shoot Ni values, thus suggesting that plants grown on peat-treated WFS may not increase risks to human and ecological receptors. Chromium was below detection levels in shoots for all peat treatments. Peat-treated substrates also promoted increased CEC values and higher water holding capacity, therefore improving the WFS agronomical properties. These results indicate that peat can be used as an amendment to assist in the phytoremediation of WFS landfill areas. However, there was evidence for increased mobilization of Cr and Ni in the substrate solution which can pose a threat to local groundwater.