TRACE METAL CONCENTRATIONS IN URBAN PARKS OF NEW ENGLAND: LAND USES, GEOCHEMICAL FINGERPRINTS, AND REGULATORY LIMITS

Surface soils from historical urban park lands may often represent the most undisturbed soil profiles within large cities and, thus, may serve as a record of past and current land use patterns. To assess the role of urban park soils as long-term sinks for contaminants resulting from anthropogenic activities, a suite of urban park surface soils and soil cores were collected from six New England cities. Trace element concentrations were analyzed using XRF and compared to park age and size, as well as to population density and industrial activity of the city. Soil core trace and major element profiles were used to evaluate autochthonous soil formation processes and link it with changing land use patterns, thereby assessing the validity of using surface soils as a single integrated point reference for urban metal loading. Principal Component Analysis aided in discerning whether distinct geochemical fingerprints exist for each city. Soils from historical parks in more populated cities with heavier industrial activity had higher heavy metal concentrations than younger parks in cities with smaller populations and less industrial activity. Twenty-five percent of samples from the three oldest parks exceeded all five New England state Pb benchmarks in existence. Surface soil from New Haven Green, the oldest park in the most industrialized city in the study as designated by number of toxic releases, had an average Pb concentration of 310 µg/g. This value is more than twice the Rhode Island state residential Pb limit, but does not exceed the regulatory limits for New Hampshire, Maine, or Connecticut. Comparison of trace element concentrations with state legislative limits highlights the need for more uniform standards across jurisdictional boundaries, as well as for limits that reflect the unique functions that urban parks support.