Mapping heavy metal soil contamination and investigating phytoremediation potential at an ex-brownfield site in Kent, UK

Milton Creek Country Park was identified as a contaminated public area with a need for remediation due to suspected high concentrations of heavy metal contamination. The extent of heavy metal contamination at Milton Creek Country Park, an ex-brownfield site, was quantified. Once known, the identification of accumulators and hyperaccumulator plants across the site was required to determine if plants that inhabit the site had any ability to remediate contamination: this would allow managers to utilize phytoextraction in order to provide cost-effective remediation of the site, whilst protecting the local ecosystem and providing a safe public green space.

Copper, zinc, nickel, iron, lead and chromium all showed above average concentrations within the soils of the site. Concentrations of lead (1896 ppm), chromium (114 ppm) and iron (44544 ppm) also provided cause for concern due to high peaking locations across the site, which are concentrations of concern to human health. 14 out of the 15 plants showed evidence of accumulation of heavy metal contaminants. Trisetum flavescens was the only species able to significantly uptake nickel, lead and chromium which is important in the remediation method. Lolium perenne, Trisetum flavescens, Plantago spp and Agrostis stolonifera were selected for the remediation of the site. These species cover a wide range of pH values as well as evidence they cover the remediation of all heavy metals required at the site. This will allow the mix of species to be able to be deployed at any area of the site which requires the most remediation.

Other factors are discussed for the method, including the addition of the management of Rubus fruricosus by means of fruit removal to prevent the consumption of accumulated iron and the addition of Trifolium repens and fencing around areas of lead pollution. These additions are added to provide extra safety for the public, allowing the site to still be used but protecting the public’s health from the pollution present.