LEAD AND EXOTIC HEAVY METAL CONTAMINATION FROM AGING INFRASTRUCTURAL PAINTS: TOBIN BRIDGE IN CHELSEA, MASSACHUSETTS

Chelsea, MA is a city with a predominantly minority population and history of environmental contamination and injustice. Chelsea and Boston, MA are connected by the Tobin Bridge which opened in 1950. This bridge has been painted with leaded paint numerous times and, consequently, has been a persistent source of lead contamination to the surrounding community. Weathering has distributed paint chips across the urban landscape including public parks and residential spaces–ultimately breaking down and persisting in soils. In response to contamination concerns, remediation efforts have been implemented, including repainting the bridge with titanium- and zinc-based paints and wrapping non-repainted portions of the bridge with tarps. However, paint chipping remains a perpetual problem and remediation has not addressed historic contamination of local soils. Understanding the impact of the Tobin Bridge on the heavy metal pollution in Chelsea will help to address ongoing environmental health concerns in the community.

To determine the Tobin Bridge’s role in Chelsea heavy metal contamination, we collected soil samples ranging from directly beneath the bridge to 4.8 km away. Paint chips from beneath the bridge were also collected to form a chemical profile for the paint. Analysis of both soil and paint chip samples was conducted using field-portable and benchtop X-Ray Fluorescence spectroscopy (XRF). Preliminary results show exotic metals like titanium, antimony, tin, and barium, and elevated concentrations of lead in soils. Paint chip analysis revealed raised concentrations of the same exotic heavy metals and high lead levels. Evidence of repainting was also identified: higher heavy metal concentrations were found on the back sides of the chips, illustrating the chemical distinction between different layers of paint.

We postulate that much of the exotic heavy metal contamination we observe in Chelsea soils is due to the long term loading of paint from the Tobin Bridge. Paint chips were observed throughout the local environment and, in conjunction with soil analysis, serve as material evidence of a connection between the Tobin Bridge and heavy metal contamination of surrounding soils. These findings suggest the importance of considering the impact of infrastructural paint weathering on urban environments.