ABSTRACT
Urban contaminated land is an international environmental problem. Decades of industrial activity with little environmental consideration have led to significant legacies of urban chemical contamination. The EA (Environment Agency for England and Wales) estimates that approximately 2 per cent of England and Wales (300,000 hectares) was affected by industrial activity and potentially contaminated (EA 2009). Although significant capability now exists to manage the problem, contaminated land remains an expensive, technically challenging proposition. Contaminated land management has been driven by the protection of human health and water resources (Rivett et al. 2002). Although ecological concerns about its conservation value (Gibson 1998) have not necessarily been ignored, it is only in quite recent times that they have figured more prominently in legislation and published guidance, for example the European Water Framework Directive (2000/60/EEC) and the EA guidance An Ecological Risk Assessment Framework for Contaminants in Soil (EA 2008a). This chapter reviews the nature of urban contaminated land relevant to urban ecology; how such land is assessed with specific emphasis on ecological risk assessment (ERA); and key issues relevant to the remediation of contaminated land and associated ecological habitat enhancement. The focus is upon the assessment of the ecological risk posed by contaminated land in that the ERA process fundamentally provides both a detailed descriptor of the specific nature of the contaminated land through the conceptual site model (CSM) as well as a quantified understanding of risks posed by the land and need for remedial actions necessary to develop ecological habitat. The chapter has a UK emphasis, but is internationally relevant, especially to areas that are undergoing rapid and recent industrialization, such as India and China. It is built around the aforementioned ERA framework proposed by the EA (EA 2008a), named ‘ERA 1’ by the EA and its supporting guidance, namely ERA 2a on CSMs (EA 2008b), ERA 2b on soil screening values (EA 2008c), ERA 2c on bioassays (EA 2008d), ERA 2d on ecological surveys (EA 2008e) and ERA 2e on attribution of cause and effect (EA 2008f ). These works are an excellent example of current best practice that is legislatively driven and provide internationally relevant guidance on the assessment and management of ecological risks associated with contaminated land. The reader is duly referred to that extensive documentation of which the later sections of this chapter provide a precis.
