Risks and benefits associated with urban green space through the lens of environmental justice

Abstract

A number of factors contribute to concerns on environmental justice in urban areas. These include a lack of green space, poor access to healthy fruits and vegetables, and high exposure to environmental contaminants. Access to soils with low contaminant bioaccessibility is critical to addressing these concerns. This is complicated due to conflicting guidance on what constitutes safe soil and how to improve the quality of urban soils. This review details the basics of the hazards associated with two ubiquitous urban contaminants: Pb and PAHs. The literature on significant exposure pathways and potential bioavailability of these contaminants is discussed. Guidance and regulatory values for both Pb and PAHs are shown and vary widely. Soil concentrations of these contaminants are often exceed regulatory values. Data from studies on urban soils for contaminant concentrations and availability reduction are presented. Use of organic amendments including compost- and biosolids-based soil products, along with gardening in raised beds are acceptable practices for growing food in potentially-contaminated soils. Yield increases associated with their use has been reported. The feedstocks for these amendments are readily available in all urban areas. Because these amendments typically have lower concentrations of contaminants than urban soils, their use will decrease total concentrations of contaminants and has been shown to improve soil and ecosystem health. Bioaccessible fractions of contaminants may also be reduced. Thus, these amendments appear to be a way to safely and productively increase urban green space. In addition, the use of residual-based soil amendments will result in additional environmental benefits due to waste diversion from landfills.