Impact of organic amendments on aerial biomass production, and phytoavailability and fractionation of copper in a slightly alkaline copper mine tailing

Abstract

In the process of phytoremediation of mine tailing land, the bioavailability of heavy metals is an important factor. Greenhouse experiment was conducted to assess the availability and uptake of copper (Cu) by maize (Zea mays L.) grown on a slightly alkaline Cu-mine tailing amended with commercial compost and chelators. A second objective was to evaluate the distribution of Cu in cultivated Cu-mine tailings. The experimental design consisted of 12 treatments resulting from the combination of four rates (0, 5, 10 and 20%, by humid weight) of peat moss-shrimp wastes compost and three rates (0, 1.2 and 2.4 dm³) of organic complexing agents applied as a 0.0025 M EDTA + 0.001 M citric acid solution before plant harvest. The results showed that compost and chelators had a positive effect on top biomass production of maize. Compared with the control, the application of compost decreased Cu_CAR and increased Cu_ORG whereas the addition of chelating solution increased Cu_SOL and Cu_EXC and decreased Cu_CAR and Cu_ORG. The Cu lability in cultivated tailing and its availability to the maize plant are highly dependent on the metal speciation in tailing. In another series of experiments, sorption of Cu by cultivated mine tailings were examined. The amounts of Cu sorbed and K _d values were highest in tailing amended with highest compost rate, and were positively correlated with tailing organic matter (OM) content and Cu bound to Cu_ORG. The results indicate that peat moss and shrimp waste containing compost could be used as a phytostabilizer by supplying OM and nutrients and as a sorbent by mitigating Cu uptake by maize. This compost is able to improve the phytoremediation of Cu-mine tailings.

Keywords:

• maize
• phytoremediation
• compost
• citric acid
• EDTA
• metal speciation

Acknowledgements

Financial support for this study was provided by the Natural Sciences and Engineering Research Council of Canada.