Urban environments have been compared to the global environment predicted at the end of the twenty-first century, in that urban areas are currently experiencing elevated atmospheric C02 concentrations, warmer temperatures, increased nitrogen loads, and elevated concentrations of pollutants (Grimm et al. 2000). It is extremely difficult to predict ecosystem responses to multiple atmospheric and climatic perturbations (Norby and Luo 2004), yet such predictions are critical, both for understanding global change as well as for quantifying critical ecosystem processes in urban areas in which large numbers of people live and work. Plants and soils in urban areas provide important ecosystem services for urban residents which may be adversely impacted by multiple pollutants in the urban environment. There is a great need for methodology to understand the effects of multiple pollutants on plants, soils, and ecosystem services, as well as for mapping ecosystem pollutant exposure and the distribution of pollutants at municipal, regional, and continental scales.