Identification of Legacy and Active Sources of Metal Contamination in Soils in Brooklyn, NY

Abstract The purpose of this study was to examine the spatial distribution and potential anthropogenic sources of Pb, Zn, Cu, Mn, and Fe in surface soils throughout Brooklyn, NY. We collected soil samples (n=1,373) from 176 different New York City parks. Metal concentrations were analyzed ex-situ using a portable X-ray fluorescence with a subset (n=350) confirmed with ICP-MS. The effect of multiple sources on metal concentrations were determined by stepwise multivariable linear regression with generalized estimating equations. Median concentrations for Pb, Zn, Cu, Fe, and Mn were 107.8 ppm, 144.7 ppm, 49.4 ppm, 14033.6 ppm, and 279.2 ppm, respectively. All metals were significantly correlated with one another (p<0.001), with the strength of the correlation ranging from a low of approximately ρ = 0.3 (Pb-Mn and Zn-Mn) to a high of ρ = 0.7 (Pb-Cu). In final multivariate modeling, scrap yards were significantly associated with Mn concentration (β = 0.075, 0.019), NPL sites was significantly associated with Pb, Fe and Mn (β = 0.134, p=0.004; β = 0.038, p=0.014; β = 0.057, p=0.037, respectively), and bridges nearby were significantly associated with Pb and Zn (β = 0.106, p=0.003; β = 0.076, p=0.026, respectively). Although manufacturing and industry have mostly left the area, smaller scrap metal recyclers are abundant and significantly increased Cu and Mn soil concentrations. In addition, NPL sites contributed to increased concentrations of all five metals within 800 m. Roadways have long been established to be sources of urban pollution; however, in our study we also found the presence of bridges within 800 m were also strongly predictive of increased Pb, Cu, and Zn concentrations.