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Brownfield land is often physico-chemically unsuitable for development without major remediation work.Ground preparation normally begins with some form of surface ripping or ploughing to relieve compaction which often forms the primary constraint to the restoration process (Rawlinson et al.2004).Lesser,but often more intractable,constraints include contamination status,and elevated concentrations of metals and arsenic in the soil may be associated with a degraded vegetation cover and reduced microbial and faunal activity in soil.One of the more obvious ways to begin to remediate these soils and to restore key functionality (decomposition and nutrient cycling),is to replenish organic matter by applying recycled organic wastes such as sewage sludges,composted greenwaste or de-inked paper waste (Dickinson 2002).This has a significant impact on the fate of pollutants in the plant/rhizosphere system and in the wider environment,and forms the focus of the present paper.As part of an urban regeneration and community forestry programme around Liverpool we have carried out tree planting experiments at more than 20 brownfield sites (Dickinson 2006; Putwain et al.2003).We have been especially concerned with soft end-use remediation strategies (Dickinson 2000),risk assessment (Dickinson et al.2000),the effect ofremediation activity on metal mobility metal and clean-up (French et al.2005; King et al.2006) and the concept of restoring healthy soils (Dickinson et al.2005).Currently we are investigating the organic matter and carbon status of remediated brownfield soils with a particular interest in increasing the usage of recycled composted greenwaste..We are developing a model of carbon storage on brownfield soils,based on detailed analysis of soil profiles,lysimetry,leachate analysis using rhizon samplers,decomposition,DOC mobility and respirometry (using an open chamber respirometer).At sites where composted greenwaste has been applied,application has generally been as a surface mulch 10 cm depth (approximately 500 t ha-1).In our studies,large compost additions readily raised soil respiration above that of urban woodland soils but it remains to be found (i) what is the residual fraction of carbon that effectively remains in the soil as carbon storage and consequently (ii) what is the realistic steady state or carrying capacity of remediated brownfield soils.Carbon stored in soils in Great Britain amounts to 86.5 times that is vegetation,with urban soils covering about 8% of the land surface of England and Wales (Milne and Brown 1997).Over the last 25 years,there has been a to a 1.6% decline per year,equivalent to 8% of UK industrial CO2 emissions (Bellamy et al.2005).