Agro-toxicological aspects of coal fly ash (FA) phytoremediation by cereal crops: effects on plant germination, growth and trace elements accumulation.

A vegetative cover is a remedial technique utilized on coal fly ash (FA) landfills for soil stabilization and for the physical and chemical immobilization of contaminants. There is a great concern, that plants planted or voluntarily growing on media with high content of FA may absorb toxic amounts of Se and/or heavy metals. If such plants are ingested, it may result in toxicity to animals or humans. Despite these objections, the utilization of FA as a growth medium for plants is an attractive alternative for disposal of FA in landfills. We hypothesized that selected plants will grow in media containing FA and/or bottom ash (BA) from several sources. Two coal FA, one from Montana semi-bituminous coal and another from North Dakota lignite alone or in combination with BA from Montana semi-bituminous coal were tested as plant growth media for the following plant species: barley (Hordeum vulgare), oats (Avena sativa), rye (Secale cereale), wheat (Triticum aestivum), regreen; a hybrid between wheatgrass (Agropyron cristatum) and winter wheat (Triticum aestivum), and triticale; a hybrid between wheat (Triticum aestivum) and rye (Secale cereale). The concentration of Al, As, B, Ba, Be, Co, Cd, Cr, Cu, Mo, Pb, Sr, Ti, Tl, and V in growth media and in young plants was determined using Inducted Coupled Plasma Spectrophotometry (ICP). All tested plant species germinated and grow in FA and/or FA + BA containing media. However, germination and/or growth of the majority of tested plants were decreased by the presence of FA and/or BA in growth media. Concentration of all analyzed elements was greater in growth media containing FA and/or BA than in soil control, and also was greater in plants grown on medium containing FA and/or BA than in soil. These data demonstrate that tested plants can grow on media consisting of coal ash, and therefore these plants can be used to cover FA or BA residue piles.