"What's in Your Soil?" - Characterizing and Mapping Spatial Patterns of Soil Quality in Chicago's Lincoln Park Neighborhood.

Cities have complex land use histories that give rise to soils that are heterogeneous in morphology, have complex genesis, and which contain high concentrations of nutrients and toxic substances, particularly lead. Little attention to date has been devoted to characterizing and mapping spatial patterns of soil quality indicators in urban soils. This presentation highlights some results of an ongoing project to characterize and map a suite of soil quality indicators in Chicago’s Lincoln Park neighborhood, one of the most affluent neighborhoods located on the city’s north side. Soil samples were collected from 66 single-family properties and from 60 city-owned parkway sites and analyzed for a suite of soil quality indicators. Soil pH and organic matter ranged from 6.2 to 9.6 and 0.338 to 29.6%, respectively. Nitrate-nitrogen and soluble reactive phosphorus concentrations ranged from 5 to 176 mg kg^-1   and 4.0 to 1723.1 mg kg^-1 respectively. Total and bioavailable Pb concentrations ranged from 3.14 to 4435.6 mg kg^-1 and 0.0 to 1307.44 mg kg^-1 (0-15.9%), respectively. Many sites showed extreme nutrient saturation, reflecting variations in soil management practices by property owners. Spatial variations in Pb concentrations reflect Chicago’s heavy industrial legacy. Both total and bioavailable lead concentrations increased from (i) southwest to northeast, parallel to prevailing long-term wind direction, (ii) with increasing building density and height and (iii) along major transportation corridors and passenger elevated train lines. With over 850 mapped urban gardens, increasing numbers of Chicagoans are potentially coming into contact with nutrient saturated and lead contaminated soil. The results of this study indicate the need for more comprehensive characterization and mapping of urban soil at the neighborhood scale, as well as the creation of programming to educate citizens on urban soil quality.