Evaluation of nitrate leaching from mine tailings amended with biosolids under Mediterranean type climate conditions [An article from: Soil Biology and Biochemistry]

This digital document is a journal article from Soil Biology and Biochemistry, published by Elsevier in 2007. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
Mine tailings are difficult to revegetate due to the lack of organic matter, severe nutrient limitations, and potential metal toxicity. Biosolids has been shown to be favorable for improving properties of mine tailings. The rates of biosolids required to reclaim mine tailings (up to 250drytha^-^1) may produce conditions where significant amounts of nitrates can leach into groundwater. Leaching column experiments were conducted to determine the influences of biosolids placement and plant cover on nitrate leaching from biosolids-amended mine tailings. PVC columns packed with 7.7kg of tailings were treated with 168g of biosolids (approximately 270kg mineral Nha^-^1). Biosolids were either placed on the surface or mixed with the tailings and half of the columns were seeded with perennial ryegrass (Lolium perenne, L.). Columns were drip irrigated at a rate of 758mm of water y^-^1. This rate was twice the average precipitation for Central Chile. All leachates were collected weekly for up to 21 weeks and analyzed for nitrate, pH, electrical conductivity, and chemical oxygen demand. The electrical conductivity and nitrate concentration of percolates decreased with time, while the pH remained constant. In some cases the percolate had nitrate concentrations greater than the maximum amount allowed for human consumption (10mg NO"3-N1^-^1). Vegetation cover and mixing the biosolids with tailings reduced NO"3-N concentrations in the percolate.