Heavy Metal Analysis of Lichen at a Massachusetts Superfund Site Reveals Previously Overlooked Contamination

Overview

Heavy metals are toxic pollutants that persist in ecosystems and bioaccumulate, causing chronic health issues such as neurological damage and cardiovascular diseases. Many of these metals are byproducts of industrial activities. Since the 1630s, industries along Lower Neponset River in Eastern Massachusetts released heavy metals into the environment of this now EPA Superfund. Despite cleanup programs initiated since 2023, much heavy metal contamination from centuries of industrial activity remains. To highlight this, we leveraged Flavoparmelia caperata (L.) Hale, an epiphytic lichen and cost -effective bioindicator, to assess heavy metal pollution at the site. We collected 88 natural lichen thalli and 25 soil samples from the Superfund, along with 3 lichen controls from MA suburban areas as local baseline. Using I nductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), we measured concentrations of 19 trace metals in lichen and soil samples. Lichen tissue exhibited significantly elevated levels of Al , Ba, Cr, Cu, Fe, Mg, Mn, Ni, Pb, V, Zn (p<0.01), with particularly severe Pb contamination. Soils exhibited mostly Pb contamination. Enrichment factor analysis reveal that F. caperata is a more effective bioaccumulator for monitoring air quality and modern environmental contamination than soil. Spearman rank correlation analysis further suggest distinct distribution patterns within site and different pollution sources for lichen and soil contamination. We conclude that lichens serve as a modern air polluti on indicator, while soils reflect long -term, localized contamination. Given that current remediation efforts focus on polychlorinated biphenyls (PCBs), we recommend a revision of strategies to address heavy metals and its associated health risks.