Research Ecologist USDA Forest Service, United States
Abstract: Urbanization has increased atmospheric deposition of pollutants on urban and downwind ecosystems. Deposition may disproportionately impact low-income and minority populations; the federal Home Owners Loan Corporation (HOLC) neighborhood assessment policy reinforced racial segregation in Portland, Oregon during the 1930s-1960s by assigning ”desirability” grades to neighborhoods, and disproportionately segregating black residents or other people of color to low grade neighborhoods that were low environmental quality and in closer proximity to pollution sources. The goal of this study is to test for legacy effects of the historic HOLC neighborhood policy by examining elemental composition of the moss biomonitor Orthotrichum lyellii collected in 2013 by the United States Forest Service at 346 sites across the Portland Metropolitan area. We found no significant correlations between HOLC neighborhood grades and S, Pb, Ni, Cu, Zn, Cd, or Cr concentrations. Nitrogen concentrations were higher for neighborhoods with the lowest HOLC grades (P=0.034) and in turn were positively correlated with Pb, Ni, Cu, Zn, Cd, Cr, and S concentrations (P< 0.05). This suggests infrastructure, industry, and historic zoning may be determining factors for N deposition. Future research will incorporate 2010 US Census Bureau block demography, N isotope composition, and resample sites in 2023 to evaluate effects of urbanization and source attribution over time.
