Rhizosphere Influence and Seasonal Impact on Phytostabilisation of Metals—A Field Study Prabha K. Padmavathiamma & Loretta Y. Li Received: 16 November 2010 / Accepted: 17 May 2011 # Springer Science+Business Media B.V. 2011 Abstract Field experiments were conducted to assess the influence of plant growth and amendment addition on phytostabilisation of copper (Cu), lead (Pb), manganese (Mn) and zinc (Zn) along highway soil in southwest British Columbia, Canada. The plant species tested were Lolium perenne L (perennial rye grass), Festuca rubra L. (creeping red fescue) and Poa pratensis L. (Kentucky blue grass) and the amendments, lime and phosphate. The treatment efficiencies were assessed during different seasons as a completely randomized factorial experiment in split plot design. The research tasks involved: (1) quantifying the seasonal extent of metal accumulation in soil and assessing the seasonal impact on metal speciation for different soil amendments and plant species; (2) determining seasonal accumulation differ- ences between sampling periods in plant parts; and (3) assessing the influence of root–soil interactions on metal dynamics. The amendments decreased the exchangeable fraction and plant uptake of all four metals. The lowest mobile fractions (exchangeable and carbonate bound) were found in soils growing Festuca for Cu, Lolium for Mn and a Lolium/Poa/ Festuca combination for Pb and Zn. Metal accumu- lation and metal dynamics in the rhizosphere soil are compared with those of the bulk soil. The final outcome was the development of a remediation strategy for all four metals involving suitable plants and amendments and incorporating seasonal and rhizosphere influences. Keywords Phytostabilisation . Root–soil interactions . Seasonal impact . Enrichment coefficient . Metal fractionation . Translocation properties . Rhizosphere soil . Bulk soil 1 Introduction A wide range of pollutants such as particulates, trace elements and petroleum hydrocarbons, which origi- nate from transportation activities, accumulate on highway surfaces in addition to direct aerial deposi- tion. Due to the impermeability of the pavement, these pollutants are delivered by highway run off during wet weather to roadside soils and potentially into streams via drainage networks (Thomson et al. 1997) and enter the food chain (Ma and Jennings 2008). Of all the contaminants in the highway system, metals are the most prevalent contaminants of concern (Hathhorn and Yonge 1996) since they are adsorbed Water Air Soil Pollut DOI 10.1007/s11270-011-0843-4 P. K. Padmavathiamma Faculty of Land and Food Systems, University of British Columbia, 2357 Main Mall, Vancouver, BC V6T 1Z4, Canada L. Y. Li(*) Department of Civil Engineering, University of British Columbia, 6250 Applied Science Lane, Vancouver, BC V6T 1Z4, Canada e-mail: lli@civil.ubc.ca