SUITMA 2005 Cairo - Health descriptors for remediated brownfield soils
SUITMA 2005 Cairo
| This abstract is about one of the papers of the Consumed mining and military areas theme of the SUITMA 2005 symposium. |
| Nicholas Dickinson,i | William Hartley,i |
| Louise Unfindell,i | Helen Rawlinson,ii |
| Philip Putwain.iii |
- i - School of Biological and Earth Sciences, Liverpool John Moores University, Liverpool, United Kingdom
- ii - The Mersey Forest, United Kingdom
- iii - Ecological Restoration Consultants, Neston, United Kingdom.
Reclamation of brownfield land contributes to a vision of a more diverse and healthy post-industrial landscape and to environmental health by improving the quality of soil. The reclamation process aims to deliver a soil that is of benefit, or at least not detrimental, to human health or controlled waters, but descriptors of soil health and quality are currently inadequate. There are no guidelines for what constitutes a healthy soil, but implicit in our understanding are measures of (i) risk management, (ii) soil biodiversity and (iii) the functional integrity of the soil (soil sustainability).
To be useful, ecological indicators have to be both sensitive to contamination and well correlated with beneficial soil functions. They must also be easy to measure and comprehensible to practitioners. This paper considers relevant descriptors in the search for well-defined measures of soil health. In Liverpool, we are currently giving particular attention to the identification of a toolbox of predictors of soil health for brownfield land that is undergoing remediation to soft end-uses (particularly community forestry) in addition to evaluating the use of recycled composted green waste as an amendment and for soil development. The objectives of this research are to identify remediation endpoints: safe and sustainable land use with improved biodiversity and functional integrity of soil. Current progress with this project is described.
A healthy soil supports plant growth, maintains a diverse soil fauna, decomposes plant and animal residues, recycles nutrients, and stores and releases water. Soil organic matter also plays a major role in carbon sequestration.
It is appropriate that we use the term ‘healthy soil’ to describe a structured, functional soil that is biodiverse and sustainable; the expected deliverable of the reclamation process. The presence or absence of soil organisms provides the most obvious visual indicator of soil health, but it is difficult to provide standardised assays that do not require highly specialist taxonomic skills or knowledge of how to use and interpret qualitative and quantitative data. Our aim is to derive an appropriate set of indicators of soil quality and to test them at a range of urban reclamation sites.
In many cases brownfield land contains residual contamination, particularly of heavy metals and arsenic, but the focus of reclamation of contaminated sites is shifting away from regaining pristine soils conditions towards cost-effective risk-based remediation measures. Currently we rely to large extent on chemical testing prior to reclamation, but analyses of total concentrations of heavy metals frequently provide a crude and inaccurate estimate of risk; mobility and lability, not the total amount of contaminant, are the most important criteria. Management of contaminated land may involve little more than a risk assessment and vegetation establishment, but it is important to understand the effect of changing soil conditions on mobility and dispersal of contaminants. Phytoremediation is also evaluated in the context of integrated management of brownfield soils. We describe experimental work that investigates the effects of woodland establishment, plant roots, earthworms and factors that influence soil processes and contaminant mobility.
