PHYTOEXTRACTION: PLANT RESPONSES FROM AN OILSHALE TAILING LANDFILL

Phytoremediation is an emerging technology that uses plants to clean up pollutants (metals and organics) from the environment. Within this field of phytoremediation, the utilization of plants to transport and concentrate metals from the soil into the harvestable parts of roots and above-ground shoots is usually called phytoextraction. phytoextraction of metals is a cost-effective approach that uses metal-accumulating plants to clean up these soils. The aim of this work is to assess the performance of phytoextraction at an industrial tailing landfill. The studying area, an oilshale tailing landfill, is located on the outskirts of Maoming, a new energy industrial city, south of China. The waste consists of processed oil shale and various chemical wastes generated from the Petrochemical Company. The landfill is 6-7 km long, about 2-3 km wide and 15 to 20 m high. Plant and soil samples were collected at different parts of the site, along the top-hillside-bottom-vicinity of the landfill and analyzed for metals such as Zn, Cu, Ni, Cr, Pb, Sr with ICP-MS. The analytical results showed that: (1) the soil beneath and near the landfill was contaminated by heavy metals, Mn concentration is as high as 2655µg/g,Fe as high as 53190µg/g, Rb as high as 506.8ug/g; (2) the same plant has different metal-accumulating capacities at its different parts, for example, Eucalytus saligna has Mn-accumulating factors of 20 for flower, 9 for stem and 5 for fruit; (3) the plants have higher accumulation capacities for Mn, for other metals according to the order Zn£¾Ni£¾Pr£¾Pb; (4) the same plant has different accumulation capacities at different parts of the site, which may be explained by the concentration effect.