Location: Northwest Irrigation and Soils ResearchTitle: Biochars reduce mine land soil bioavailable metals Author
|Novak, Jeffrey - Jeff|
Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/9/2017
Publication Date: 3/17/2017
Citation: Ippolito, J.A., Berry, C.M., Strawn, D.G., Novak, J.M., Levine, J., Harley, A. 2017. Biochars reduce mine land soil bioavailable metals. Journal of Environmental Quality. 46:411-419. Interpretive Summary: Two different biochars, made from pine beetle-killed lodgepole pine and tamarisk trees, were added at 0, 5, 10, and 15% by weight to four different mine land soils containing various amounts of cadmium, copper, lead, and zinc. Increasing biochar application rates caused soil pH to increase and caused bioavailable metals to decrease. A sequential extraction procedure showed that the metals formed stable associations with carbonates and hydroxide phases in the soil, suggesting that the metals would remain stable as long as the elevated soil pH is maintained.
Technical Abstract: Biochars are being proposed as an amendment to remediate mine land soils. Therefore, two different feedstocks (pine beetle-killed lodgepole pine [Pinus contorta] and tamarisk [Tamarix spp.]), within close proximity to mine land affected soils, were used to create biochars in order to determine if they have the potential to reduce metal bioaccessibility. Four different mine land soils, contaminated with various amounts of cadmium, copper, lead, and zinc, received increasing amounts of biochar (0, 5, 10, and 15% by weight). Soil pH and metal bioaccessibility were determined, and the European Community Bureau of Reference sequential extraction procedure was employed to identify pools responsible for potential shifts in bioaccessibility. Increasing biochar application rates caused increases in soil pH (initial: 3.97; final: 7.49) and 55 to 100% (no longer detectable) decreases in metal bioaccessibility. The sequential extraction procedure supported the association of cadmium with carbonates, copper and zinc with oxyhydroxides and carbonates, and lead with oxyhydroxides; these phases were likely responsible for the reduction in heavy metal bioaccessibility. This study proved that feedstocks local to abandoned mining operations could subsequently be used to create biochars and reduce heavy metal bioaccessibility in mine land soils.