Journal of Hazardous Materials 301 (2016) 179–186 Contents lists available at ScienceDirect Journal of Hazardous Materials journal homepage: www.elsevier.com/locate/jhazmat Lead and copper immobilization in a shooting range soil using soybean stover- and pine needle-derived biochars: Chemical, microbial and spectroscopic assessments Mahtab Ahmad a,b,1 , Yong Sik Ok a,1 , Anushka Upamali Rajapaksha a , Jung Eun Lim a , Byung-Yong Kim c , Jae-Hyung Ahn c , Young Han Lee d , Mohammad I Al-Wabel b , Sung-Eun Lee e,∗ , Sang Soo Lee a,∗ a Korea Biochar Research Center & Department of Biological Environment, Kangwon National University, Chuncheon 200-701, Republic of Korea b Soil Sciences Department, College of Food and Agricultural Sciences, King Saud University, PO Box 2460, Riyadh 11451, Saudi Arabia c Agricultural Microbiology Division, National Academy of Agricultural Science, Rural Development Administration, Wanju 565-851, Republic of Korea d Division of Plant Environment Research, Gyeongsangnam-do Agricultural Research and Extension Service, Jinju 660-360, Republic of Korea e School of Applied Biosciences, Kyungpook National University, Daegu 702-701, Republic of Korea h i g h l i g h t s • Biochar immobilizes Pb and Cu in a contaminated shooting range soil. • Soybean stover-biochar is an efficient metal immobilizer than pine needle-biochar. • Biochar produced at 700 ◦ C showed significant potential of sequestering C in soil. • Biochar showed less impact on the bacterial community than feedstock biomass. a r t i c l e i n f o Article history: Received 10 March 2015 Received in revised form 10 August 2015 Accepted 15 August 2015 Available online 20 August 2015 Keywords: Biochar Metal immobilization Soil microbe Pyrosequencing EXAFS a b s t r a c t Biochar (BC) could be a potential candidate for the remediation of metal contaminated soil. Mechanistic understandings are needed for the appropriate selection of BC and investigating molecular microbial ecological interactions. The soybean stover-derived BCs were more effective in immobilizing Pb (88%) and Cu (87%) than the pine needle-derived BCs in a contaminated shooting range soil. The sequential chemical extractions indicated that BCs stimulated the geochemical transformation of metal species. Spectroscopic investigations using scanning electron microscopic elemental dot mapping and extended X-ray absorption fine structure spectroscopic measurements showed that Pb in the BCs amended soils was immobilized by the formation of stable chloropyromorphite. Soil organic C and microbial activity were also enhanced by BC. The non-labile C fraction in the soil amended with BCs produced at 700 ◦ C was increased. Biochars showed less impact on the bacterial community than feedstock biomass as pro- mulgated by the pyrosequencing of 16S rRNA gene. The feedstock type (namely soybean stover and pine needles) was the main factor influencing the BCs efficacy on metals’ (im) mobilization and bacterial health in soils. © 2015 Elsevier B.V. All rights reserved. ∗ Corresponding authors. Fax: +82 33 259 5563. E-mail addresses: selpest@knu.ac.kr (S.-E. Lee), sslee97@kangwon.ac.kr (S.S. Lee). 1 The authors wish it to be known that the first two authors should be regarded as joint first authors. 1. Introduction Biochar (BC) has been defined as “a porous carbonaceous solid produced by the thermochemical conversion of organic materials in an oxygen depleted atmosphere” [1]. BC is commonly produced from crop residue [2], wood biomass [3], animal litter [4], and solid waste [5], thereby, decreasing the associated pollution load by uti- lizing or recycling these waste materials. Because of its high organic C content, BC has the potential to serve as a soil conditioner to improve its physico-chemical and biological properties [6–8]. BC is http://dx.doi.org/10.1016/j.jhazmat.2015.08.029 0304-3894/© 2015 Elsevier B.V. All rights reserved.