Phytomanagement

Successful phytomanagement creates value from contaminated land while minimising environmental risk. Plant transpiration and root-growth to immobilise contaminants by reducing leaching, controlling erosion, creating an aerobic environment in the root-zone, and adding organic matter to the substrate that binds contaminants. Some plants can kill pathogens in biosolids.

Phytoextraction removes TEs from the soil by repeated crops of plants that accumulate large amounts of one or more target TEs in their above-ground biomass. The harvested plant material is removed from the site. There are few examples of successful phytoextraction. This technology is limited by the long period required for cleanup, the restricted number of target TEs that can be extracted, the limited depth that can be accessed by roots, and the difficulty of producing a high-biomass crop of the desired species. There is also concern about TE-accumulating plants providing an exposure pathway for toxic elements to enter the food chain. The addition of chelants to enhance plant-TE uptake, invariably increases the risk of TE leaching.

Phytoremediation technology is site specific due to the plethora of environmental variables that affect plant growth and TE mobility. Most contaminated sites contain a heterogeneous mixture of several elemental and organic contaminants. Plant-growth may be limited by other environmental variables, such as low pH, low nutrient availability, salinity, insufficient aeration or low water availability. The commercial success of phytoremediation is thus dependent on convincing decision makers that phytoremediation can satisfy environmental regulations. Obviously, field demonstrations at each site are not practical Our current research aims to elucidate the key mechanisms of plant-TE interactions to develop mechanistic models are required to calculate the effect of phytoremediation on TE fluxes. Central to such models is an understanding of root-TE interactions in these typically heterogeneous media.

Phytomanagement of wood-waste. The phytomanagement of a five hectare wood waste pile in New Zealand. The trace elements of concern are boron, copper, chromium and arsenic. Details of this project can be found in Robinson et al. (2003a).
Phytoremediation potential. The Tui Mines, Te Aroha, New Zealand leach large amounts of lead and other toxic trace elements into local waterways. In the summer months, lead-contaminated dust blows into surrounding areas, polluting soils and water. This trial plot demonstrates that phytoremediation can provide a low-cost means to eliminate dust and reduce leaching.
Phytoremediation decision support system (Phyto-DSS) A mechanistic model that calculates the effect of phytomanagement. The Phyto-DSS indicates the feasibility of phtoremediation and can be used to develop land management strategies.

Phytomanagement case studies

Kopu wood-waste pile

Disused sheep-dip site

Trial on Tui mine tailings

Trial on Werribee biosolids

Phytomanagement publications

Phytomanagement reviews

Robinson BH, Anderson CWN, Dickinson NM (2015). Phytoextraction: where's the action? Journal of Geochemical Exploration 151,34-40.

Robinson BH, Bañuelos GS, Conesa HM, Evangelou MWH, Schulin R (2009). The phytomanagement of trace elements in soil. Critical Reviews in Plant Sciences 28(4), 240-266.