Book with abstracts from the COST Action 0905 meeting in ... - UMB

THE ROLE OF BIOCHAR IN THE PHYTOREMEDIATION OF
METAL/METALLOID CONTAMINATED SOILS.
Luke Beesley 1 , Eduardo Moreno-Jimenez 2 , Jose L Gomez-Eyles 3
1 The James Hutton Institute, Craigiebuckler, Aberdeen, UK.
2 Universidad Autónoma de Madrid, 28049 Madrid, Spain.
3 University of Maryland Baltimore County, Baltimore, Maryland 21250, United States.
Keywords: Biochar, contaminated soils, heavy metals, phytoremediation, uptake.
Biochar has been evaluated for its role in improving soil quality and sequestering carbon, with
much less attention paid to soil clean-up and remediation. In the following study a hardwood
biochar and greenwaste compost alone and in combination were mixed with two contaminated
soils (As, Cd, Cu, Pb and Zn) from former industrial sites and, following environmental
exposure, pore water was collected and ryegrass (L. perenne L. var. Cadix) germinated to
determine the amendments affects on i) solubility/mobility of the elements and ii) uptake and
phytotoxicity to ryegrass.
Biochar was most efficient at reducing Cd and Zn in pore water, decreasing phytotoxicity to
ryegrass, but mobilized small concentrations of As. Copper in pore water was also reduced by
a decrease in dissolved organic carbon (DOC) and co-mobility. Greenwaste compost was
more efficient for immobilizing Pb than biochar alone but combining greenwaste compost and
biochar provided the best conditions for ryegrass growth and yield because of the
immobilization of metals and the input of N and P from compost. Despite some reductions in
ryegrass shoot concentrations of metals after amendment, the large biomass increase raised
harvestable amounts of the metals, increasing food chain transfer potential. An assessment
should therefore be made as to whether maximum reductions in plant concentrations or
maximum reduction in harvestable amounts of metals are required to ensure amendments may
be suitably deployed to maximize their effects.