Measurements of heavy metals in the moss Orthotrichum lyellii collected using community science in the Duwamish Valley, Seattle, Washington, U.S.A.

Heavy metals concentrations often vary at small spatial scales not
captured by air monitoring networks, with implications for environmental
justice in industrial-adjacent communities. Pollutants measured in moss
tissues are commonly used as a screening tool to guide use of more
expensive resources, like air monitors. We piloted a community science
approach, engaging over 55 people from nine institutions, to map heavy
metals using moss in two industrial-adjacent neighborhoods. Local youth
led sampling of the moss Orthotrichum lyellii from trees across a
250×250-m sampling grid (n = 79). We compared their data with
expert-collected samples (n = 19) using Principal Components Analysis and
Procrustes Analysis. We mapped 21 chemical elements measured in moss,
focusing on 6 toxic ‘priority’ metals: arsenic, cadmium, chromium, cobalt,
lead, and nickel. We compared local data, using t-tests and boxplots, with
two ‘reference datasets’ of O. lyellii collected in Portland, Oregon, and
in Seattle City Parks. We also use Principal Components Analysis to
describe major gradients in metals in the study area. Our data submission
includes two R scripts and four datasets of heavy metals in moss,
including the two reference datasets, which will enable replication of our
analyses as well as novel analyses.