RESEARCH ARTICLE Increased bioavailability of metals in two contrasting agricultural soils treated with waste wood-derived biochar and ash P. Lucchini & R.S. Quilliam & T.H. DeLuca & T. Vamerali & D.L. Jones Received: 18 June 2013 /Accepted: 22 October 2013 # Springer-Verlag Berlin Heidelberg 2013 Abstract Recycled waste wood is being increasingly used for energy production; however, organic and metal contaminants in by-products produced from the combustion/pyrolysis resi- due may pose a significant environmental risk if they are disposed of to land. Here we conducted a study to evaluate if highly polluted biochar (from pyrolysis) and ash (from incineration) derived from Cu-based preservative-treated wood led to different metal (e.g., Cu, As, Ni, Cd, Pb, and Zn) bioavailability and accumulation in sunflower (Helianthus annuus L.). In a pot experiment, biochar at a common rate of 2 % w /w, corresponding to ∼50 t ha -1 , and an equivalent pre-combustion dose of wood ash (0.2 % w /w ) were added to a Eutric Cambisol (pH 6.02) and a Haplic Podzol (pH 4.95), respectively. Both amendments initially raised soil pH, although this effect was relatively short-term, with pH returning close to the unamended control within about 7 weeks. The addition of both amendments resulted in an exceedance of soil Cu statutory limit, together with a significant increase of Cu and plant nutrient (e.g., K) bioavail- ability. The metal-sorbing capacity of the biochar, and the temporary increase in soil pH caused by adding the ash and biochar were insufficient to offset the amount of free metal released into solution. Sunflower plants were negatively affected by the addition of metal-treated wood-derived biochar and led to elevated concentration of metals in plant tissue, and reduced above- and below-ground bio- mass, while sunflower did not grow at all in the Haplic Podzol. Biochar and ash derived from wood treated with Cu- based preservatives can lead to extremely high Cu concentra- tions in soil and negatively affect plant growth. Identifying sources of contaminated wood in waste stream feedstocks is crucial before large-scale application of biochar or wood ash to soil is considered. Keywords Arsenic . Black carbon . Contaminated land . Copper . Metal pollution . Wood preservatives Introduction Organic wastes are of global concern due to the large volumes produced and the need to dispose of them safely (Jones and Healey 2010). Traditionally, organic waste has been disposed of by incineration or landfill, but recently there has been a tendency to recycle waste and prevent and reduce biogenic waste by adopting a more sustainable waste management program (Vehlow et al. 2007; Del Borghi et al. 2009). Signif- icant strategies for large-scale recycling of organic waste material include the production of safe and efficient soil amendments, e.g., through anaerobic digestion or composting, which can be incorporated into agricultural soils (Park et al. 2011; Williams 2005). This practice, in addition to reducing Responsible editor: Zhihong Xu P. Lucchini Department of Agronomy, Food, Natural Resources, Animals and Environment, University of Padova, Viale dell’Università 16, 35020 Legnaro, Italy P. Lucchini : T. DeLuca : D. Jones School of Environment, Natural resources and Geography, Bangor University, Bangor, Gwynedd LL57 2UW, UK R. Quilliam (*) Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, UK e-mail: Richard.Quilliam@stir.ac.uk T. DeLuca School of Environmental and Forest Sciences, University of Washington, 107 Anderson Hall, Seattle, WA 98195-2100, USA T. Vamerali Department of Food Sciences, University of Parma, Parco Area delle Scienze 11/A, 43100 Parma, Italy Environ Sci Pollut Res DOI 10.1007/s11356-013-2272-y