Portland Underground: Exploring Urban Soils in Maine

Urban Farm DB summary

This study characterized urban soils in a low-income neighborhood of Portland, Maine, that was heavily industrialized in the late 1800s, examining seven pedons for particle size, cation exchange capacity (CEC), base saturation, exchangeable bases, pH, and trace elements (Pb, Cr, Cu, Co, Cd, Ni, Zn, Hg, Ti, Zr). The soils contained numerous artifacts and showed a high degree of horizontal and vertical spatial variability; several trace elements were present at elevated levels, with lead (Pb) the dominant metal in surface horizons (600 mg/kg), and many metals correlated with each other and with iron and aluminum, and some with clay content and pH, though the study concludes that mapping soil units by specific trace element ranges would be difficult given the extreme variability observed.