Native Moss as a Screening Tool for Solid Waste Incineration

Moss lack roots, so they absorb water and nutrients from the atmosphere. In doing so, they also absorb and store whatever compounds happen to be in the air, including pollutants. Because of this unique physiology, the Forest Service has used mosses as bioindicators—living organisms that can help monitor environmental health.

Photo Credit

Janet Ohmann

Community volunteers  are trained to collect moss.

Building on work using tree moss as a bioindicator of pollution in Portland, Oregon, and Seattle, Washington, Sarah Jovan, a research ecologist with the Forest Service, explored using the same moss as a screening tool for emissions around a solid waste incinerator in rural Oregon. Trained community volunteers helped to collect 36 moss samples along a 20-mile transect extending out from the incinerator, located in Brooks, Oregon. Jovan’s collaborators analyzed the moss samples in a laboratory for the presence of 40 elements, including 14 rare earth elements that have been previously unexplored as byproducts of solid waste incinerators. Jovan and her collaborators then modeled the relationships between element concentrations and distance from the facility.

This research provides the first evidence of trace element contamination in the area. These findings can serve as a starting point for stakeholders to explore regulatory and community concerns

Purpose

The Forest Service has been using mosses and lichens as bioindicators—living organisms that can help monitor environmental health—since the 1960s. This study expands on previous moss bioindicator work in Portland and Seattle by exploring whether the same common species of native moss, Orthotricum spp., can serve as a screening tool for solid waste incinerator emissions. The low cost of using moss bioindicators allows for extensive sampling that can offer an initial view of pollution patterns.

Key Findings

This work provides new evidence supporting the use of Orthotricum spp. as a biomonitoring tool for assessing trace elements around solid waste incinerators. The chemical signatures detected in the moss samples pointed to incineration as a source, potentially through both stack and fugitive dust emissions.

• Three heavy metals commonly associated with incinerator stack emissions—lead, mercury, and cadmium—were strongly correlated with distance from the facility. The study’s models suggested that most deposition of these elements occurs within 5 miles of the incinerator.
• Trace metals often associated with incinerator ash, such as arsenic and chromium, had localized peaks near the incinerator, suggesting possible fugitive dust emissions.
• Three novel tracer elements for solid waste incineration were also identified and warrant further study—europium, gadolinium, and cesium.

Benefits to Managers and Society

This study was initiated in response to state-level legislative changes and community concerns about emissions from an older incinerator that burns some medical waste. Although concentrations of air contaminants in moss cannot be used to track human health and regulatory thresholds, they provide a valuable empirical starting point for stakeholder discussions and can help inform regulatory follow-up.

This study also demonstrates how moss biomonitoring can help characterize and reveal the geographic reach of incinerator emissions. The high variability of incinerator emissions, in composition and over time, can be a challenge for traditional monitoring approaches. But because moss can accumulate many pollutants over time, datasets like those generated in this study can provide a valuable long-term perspective of emissions.

Project Deliverables

Putting Biomonitors to Work: Native Moss as a Screening Tool for Solid Waste Incineration

Keywords: Moss, biomonitoring, bioindicator, Orthotricum, atmospheric deposition, heavy metals, trace metals