RETENTION OF TRACE METALS IN URBAN FORESTS AND SOILS NEAR MUNICIPAL WASTE INCINERATION FACILITIES IN NORTHEASTERN U.S

Municipal waste incineration facilities emit unknown quantities of trace metals and their impacts on human and ecosystem health are poorly understood. Depending on their issued permit, these waste incineration facilities may incinerate between 100 to 2000 tons per day. Given the quantity of waste being incinerated, it is likely trace metals are being released to the surrounding communities, many of which include primarily low income households. Urban forests are useful as indicators for trace metal contamination because they are able to store these metals both in soils as well as in plants able to uptake them.

Our study aims to establish a connection between proximity to waste incineration facilities and increased concentrations of trace metals in surrounding urban forests. Second, we sought to determine which trace metals are present as well as their bioavailability to plants.

Three cities were sampled for this study: Springfield, MA, Hartford, CT, and Poughkeepsie, NY in the summer. In 2017, soil and plant samples were collected in cardinal directions around each waste incinerator. In 2018, four quadrants were planned out to form a grid with 2-3 sites sampled within each quadrant. Plant samples from dominant trees were dried, ashed, and digested in aqua regia and diluted in preparation for ICP-MS analysis. Soil samples were dried and sieved before being digested with aqua regia. Ammonium acetate extractions were used to determine quantities of bioavailable fractions, not bound within minerals.

There were a few instances of elevated metal levels in Poughkeepsie with elevated levels of metals such as V in the eastern and southern sites, and Cd in the western site. Most interesting was Springfield because every site had elevated levels of at least one metal. Elements found at elevated levels included V, Pb, and In. While there were elevated levels of some metals such as Mn and Zn in the northern site, there was little evidence of elevated trace metal concentrations from samples collected in 2017 at the Hartford sites. Our results demonstrate the capacity of urban forest soils to serve as indicators and reservoirs for trace metals.