Non-aqueous phase liquids (NAPLs) are persistent sources of contamination in the ground, providing a long-term supply of dissolved phase contamination and taking significant periods to dissipate naturally. Light NAPLs (LNAPLs) take the form of a separate phase within the ground, often as individual ganglia in pore spaces within the capillary zone such that the contaminated region is diffuse and comprised of many unconnected small contaminant sources. Consequently, remedial action is challenging and success may be limited to ex-situ remediation techniques. The ability of plants to phytoremediate dissolved-phase contamination is well known, but the impact of LNAPLs on plant growth and subsequent contaminant behaviour is largely unknown. Experimental work with ryegrass (Lolium perenne) is presented, exploring the impact of the physical presence of an LNAPL (mineral oil) on plant growth, root distribution and oil removal. The presence of the oil was found to significantly impact root biomass and distribution, leading to zones of increased root growth alongside decreased shoot growth. Significant removal of the LNAPL was noted in both hydroponic conditions and planted soil.
Phytoremediation Ryegrass Mineral oil Non-aqueous phase liquids
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