BIOCHAR FOR A SUSTAINABLE ENVIRONMENT Bioenergy-derived waste biochar for reducing mobility, bioavailability, and phytotoxicity of chromium in anthropized tannery soil Indika Herath 1 & M. C. M. Iqbal 2 & Mohammad I. Al-Wabel 3 & Adel Abduljabbar 4 & Mahtab Ahmad 3 & Adel R. A. Usman 3 & Yong Sik Ok 5 & Meththika Vithanage 1 Received: 7 August 2015 /Accepted: 1 December 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract Purpose This study was aimed to investigate the potential of biochar (BC), a waste byproduct of a bioenegy industry, Sri Lanka, as a soil amendment to immobilize and reduce the phytotoxicity of Cr in tannery waste-polluted soil (TWS). Materials and methods The TWS and bioenergy waste BC were characterized for physio-chemical parameters. A pot ex- periment was conducted by adding three BC application rates, 1, 2.5, and 5 % (w/w) to investigate the immobilizing capacity and bioaccumulation of chromium (Cr) in tomato plants (Lycopersicon esculentum L.). Soils and plants were digested via microwave digestion and analyzed for total Cr. Further, sequential extraction was conducted to assess the fractionation of Cr before and after the application of bioenergy waste BC on TWS. Results and discussion The total Cr concentration in TWS was 12,285 mg/kg. The biomass of tomato plants grown in the 5 % BC amendment doubled compared to the biomass in BC-unamended soil. Bioaccumulation of Cr in plants grown in 5 % BC-amended TWS showed a decrease by 97 % com- pared to that of the BC-unamended soil. The CaCl 2 extract- ability of Cr indicated that the bioavailability of Cr in the 5 % BC amendment has decreased by 68 % compared to the con- trol. Sequentially extracted Cr in the exchangeable fraction decreased by 98 % in the 5 % BC amendment. Conclusions Pore diffusion, and adsorption via π-π electron donor-acceptor interactions were the primary mechanisms to be involved in the Cr retention in BC. Results suggested that the addition of BC to TWS reduces the mobility, bioavailabil- ity, and phytotoxicity of Cr in tomato plants. Keywords Adsorption . Bioenergy . Immobilization . Phytotoxicity . Sequential extraction 1 Introduction Presence of excessive levels of heavy metals in soils is a widespread environmental problem due to its serious conse- quences for agricultural crop productivity and human health. Of the heavy metals of greatest environmental and toxicolog- ical concern, Cr is generally considered to be one of the most severe and high-risk pollutants originating from anthropogen- ic activities. Many industrial operations such as dye produc- tion, leather tanning, anodizing of aluminum, cooling towers, electroplating, and steel production have been seriously con- tributed to the release of Cr into the environment at excessive levels to adjacent water systems and to soil (Almaroai et al. 2014). On the other hand, Cr may directly release into the environment from Ultramafic bodies such as serpentine soil Responsible editor: Jianming Xu * Meththika Vithanage meththikavithanage@gmail.com 1 Chemical and Environmental Systems Modeling Research Group, National Institute of Fundamental Studies, Hantana Road, Kandy, Sri Lanka 2 Plant Biology Laboratory, National Institute of Fundamental Studies, Hantana Road, Kandy, Sri Lanka 3 Soil Sciences Department, College of Food and Agriculture Sciences, King Saud University, Riyadh, Saudi Arabia 4 Industrial Psychology, College of Education, King Saud University, Riyadh, Saudi Arabia 5 Korea Biochar Research Center and Department of Biological Environment, Kangwon National University, Chuncheon 200-701, South Korea J Soils Sediments DOI 10.1007/s11368-015-1332-y