BSLA Fieldbook BSLA 2014 Fall Fieldbook - Page 74

BSLA / TOOLBOX POLLUTANT PURGING PLANTS Us in g Phy t ot e c h n olog i e s To Cl e a n Up C ont ami n at e d S o i l s A n d G ro u n dwat e r KATE KENNON, ASLA S o you’ve had the soil tested and it’s not good news. Can plants help remediate your site’s contaminants? Costeffective phytotechnology (phytoremediation) plantings can be effective in mitigating on-site pollutants, but these interactions are complicated, sometimes taking decades for remediation, and many times plant-based remediation strategies are not a good fit for environmental cleanup. When do they work and when don’t they? There is a lot of confusion around what phytotechnology can and cannot accomplish. However, with careful research and planning, integrating this relatively new technology into design work can result in huge financial and environmental benefits. Definition Phytotechnology is the use of vegetation and their associated microbes to remediate, contain or prevent contaminants in 72 BSLA BELOW Potential contaminants can be anticipated by site program and landscape systems can be designed to intercept contamination events before they occur. soils, sediments and groundwater. The term phytoremediation, where plants are used to remediate sites that are already polluted, is often used interchangeably with phytotechnology, but is only one subset of the field. Phytotechnology is a much broader term that includes techniques such as pre-emptive installation of vegetation to mitigate ecological problems before they actually occur, as well as stabilization of pollutants on site, beyond just contaminant removal. Green roofs, constructed wetlands, bioswales, bioenergy crop cultivation and phytoremediation plantings are all forms of phytotechnology, a term which encompasses all uses of plants to meet environmental and technological goals. History of the Field The field of phytotechnology in the US was named and formally established in the 1980s. In the 1990’s a large number of phytotechnology greenhouse and lab experiments were published, showing a potential for plant-based clean-up approaches to a broad range of pollutants in groundwater and soils across many site contexts. Quite a few plants found to hyperaccumulate metals were discovered during the same time period, and