HEAVY METAL CONTAMINATION OF SOIL AND PLANTS ASSOCIATED WITH ILLEGAL GARBAGE BURN PILES, WEST HAVEN, VT, USA

The Nature Conservancy owns and manages a 4000-acre preserve in West Haven, VT (USA), bounded to the south by the Poultney River and to the west by the southern end of Lake Champlain. The preserve is home to 11 rare/uncommon animal species and 18 rare/uncommon plants. Along the banks of the river are several illegal garbage piles that are routinely set on fire. Burned materials include household trash, construction debris, and commercial waste (including electronics). Ash from these burn piles contains high levels of several heavy metals (up to hundreds of ppm As and thousands of ppm Cu, Pb, Cr and Zn). Metal concentrations vary with time and from pile to pile, due to the changing nature of the materials being burned, the age of the burn pile, weather events, and seasonal changes to river level. One burn pile has been sampled three times in the past four years; Pb concentrations have varied between 1270 and >5000 ppm, Cu between 424 and >10,000 ppm, Zn between 7900 and 12,500 ppm, Cr between 261 and 1230 ppm, Mn between 1260 and 2170 ppm, and As between 147 and 460 ppm. Background levels (taken from a presumed uncontaminated site 1 km from the burn piles) are well within the normal range for soils (e.g. sample contains 16 ppm Pb, 11 ppm Cu, 60 ppm Zn, 2.8 ppm As, 67 ppm Cr). Two young trees (American hornbeam and white ash) growing within 10 m of the largest burn pile were also analyzed for metal content. In general, the roots show the greatest uptake of metals, followed by bark, then leaves. Metal concentrations in plant material are below background values, with the exception of Cu in the white ash (104 ppm in root, 184 ppm in bark, 27 ppm in leaves) and As in the hornbeam root (6.3 ppm). Metal concentrations vary directly with that of soil next to the roots. The site gets flooded seasonally (one burn pile sampled in November, 2013, was completely submerged in June, 2014), suggesting that metals may be periodically leached from the soil and carried downstream (into Lake Champlain), or may potentially be introduced from other contaminated sites upstream (such as a landfills, wastewater treatment facilities, and municipal runoff). However, the proximity of contaminated soil to burn piles suggests that the piles are a major source of elevated metal concentrations at this site.