Potential for Phytoremediation of Polychlorinated Biphenyl-(PCB)-Contaminated Soil

Abstract

Weathered soils contaminated with commercial-grade Aroclor 1260 from three sites in Canada were used to investigate the polychlorinated biphenyl (PCB) phytoextraction potential of nine plant species (Festuca arundinacea, Glycine max, Medicago sativa, Phalaris arundinacea, Lolium multiflorum, Carex normalis, and three varieties of Cucurbita pepo ssp. pepo) under controlled greenhouse conditions. The soils used varied in PCB concentration (90-4200 microg/g) and total organic content (0.06-2.02%). Greenhouse experiments controlled for PCB volatilization through the use of a vented enclosure and by isolating the contaminated soils with parafilm. After 8 wks, PCB concentrations of 47-6700 microg/g were observed in root tissues. Although PCB concentrations in shoot tissues were lower (< 1-470 microg/g), the absolute amounts of PCBs observed in shoot tissue were significant (1.7-290 microg) once shoot biomass was accounted for. Congener signatures indicated that tetra- to hexa-chlorobiphenyls contributed the largest proportions to shoot tissues, but hepta-to nona-chorobiphenyls were also present in measurable amounts. Overall, the results indicate that varieties of C. pepo were more effective at extracting PCBs from soil than other plants screened The evidence suggests that this was mainly due to root uptake of PCBs and tranlocation to the shoots, rather than volatilization of PCBs from soil. All plants screened showed signs of stress in the most highly contaminated soil (4200 microg/g), but not in the two lower PCB contaminated soils (250 and 90 microg/g, respectively). No detectable decreases in soil PCB concentrations were observed in these short-term greenhouse experiments, but the results suggest that this may be achievable through multiple plantings.

The uptake of persistent organic pollutants by plants

“…In these plants, PCB translocation from roots to stalks and from stalks to leaves took place only with respect to trichloro-PCBs congeners. Similarly, Zeeb et al (2006) determined higher levels of PCBs (1.7-288 μg/kg) in the aboveground biomass of Cucurbita pepo, with the highest portion of tetra-, pentaand hexachlorobiphenyls [42]. Sunflower roots had a higher amount of these more chlorinated congeners compared to maize roots.…”

Invasive species may offer advanced phytoremediation of endocrine<br>disrupting chemicals in aquatic ecosystems

“…For example, some fruit species have been shown to accumulate BPA and PCBs in their fruit (i.e. Kang et al, 2006;Zeeb et al, 2006). Studies have shown that examining the symbiotic associations of the plants with various bacteria and fungi may be important when determining the uptake capacity of phytoremediators as well.…”

Field and Greenhouse Studies of Phytoremediation with California Native Plants for Soil Contaminated with Petroleum Hydrocarbons, PAHs, PCBs, Chlorinated Dioxins/Furans, and Heavy Metals

“…As stated previously, studies have shown the uptake of PCB's (Zeeb et al 2006;Ficko, Rutter, and Zeeb 2010) and dioxins (Huelster, Mueller, and Marschner 1994) into plant tissue. But PCB metabolism in plants is slow and dioxins have not yet been shown to degrade within the plant (Campanella, Bock, and Schröder 2002).…”

“…Alfalfa and other plant species have been shown by several studies to extract PCBs from soil (Ficko et al, 2010;Greenwood et al, 2011;Liu & Schnoor, 2008;Xu et al, 2010;Zeeb et al, 2006). However, PCB degradation within the plant does not appear to be the primary mechanism of phytoremediation.…”

“…Alfalfa and other plant species have been shown by several studies to extract PCBs from soil or water (Zeeb et al 2006;Ficko, Rutter, and Zeeb 2010;Xu et al 2010;Ying Teng et al 2010;Liu and Schnoor 2008;Greenwood, Rutter, and Zeeb 2011). Chlorinated dioxins can also be extracted from the environment using plants (Campanella and Paul 2000;Huelster, Mueller, and Marschner 1994).…”