PHYSICAL, CHEMICAL AND MINERALOGICAL VARIATIONS IN URBAN SOILS, JERSEY CITY, NEW JERSEY

Urban soil, the primary receptor of urban contamination, is an ideal material to assess the surface environmental quality in urban areas. Urban soils are not used for massive food production, though community-garden and food-coop projects are becoming increasingly popular in many cities, including Jersey City, NJ, where extensive urbanization and industrialization have had detrimental effects on environmental quality since the beginning of the 19^thcentury. Physical, chemical and mineralogical characteristics of urban soils ultimately control the distribution and dispersion of inorganic contaminants (heavy metals), and their potential environmental availability. Young children playing on and in urban soils are the most vulnerable group from a human health perspective.

In our previous studies we determined particle size distribution of top-soils collected from public parks in Jersey City and examined the variation and distribution of heavy metal concentrations (As, Cu, Cr, Pb, Zn, Fe and Mn) in different size fractions: “coarse” (<2 mm and > 63µm) and “fine” (<63µm). The level of enrichment of heavy metal in the fine-sized fraction compared to those in the coarse-sized varied significantly depending on the sample location and type of elements. In this study, we focus on the mineralogical composition of these urban soils and their variations in different size fractions in order to elucidate the role of mineralogy in the distribution of heavy metal concentrations in the soils. Mineralogical and chemical compositions of these urban soils (by utilizing a portable handheld pXRF (NITON XL3t) and a bench top XRD (Rigaku ©), respectively) were compared with those of the background soil samples (Boonton Series) from a soil profile representing O, A and E horizons. The urban soils are dominated by quartz, K-feldspar, plagioclase with trace amount of illite-mica, chlorites and clay minerals. In addition, poorly crystalline Fe-and Mn-oxide/hydroxides and heavy minerals (e,g,, rutile) were identified in some samples. In general, relative abundances of clay, chlorite and illite-mica in the fine-size soil fraction of the soils are higher than those in the coarse-size fraction, while the relative abundances of K-feldspar and plagioclase are lower.