Scientists Hang Moss Bags Along Russian Highways to Track Traffic Pollution

Researchers in Russia recently conducted a study examining how effectively plants can absorb roadside pollutants by hanging bags of moss beside three busy central Russian highways. The scientific work aimed to measure the volume of traffic-related air contamination trapped by the vegetation over an exposure period. Published in the Journal of Hazardous Materials, the investigation provides a detailed look at how specific plant species react to vehicular emissions.

The project focused on the Leningradskoye, Yaroslavskoye, and Dmitrovkoye highways. To isolate the impact of traffic alone from other potential contaminants, the research team deliberately chose highway stretches that lacked any other major industrial or urban pollution sources in the immediate vicinity.

The study utilized Sphagnum girgensohnii, a moss species widely recommended by scientists for biomonitoring air pollution. In May 2023, researchers gathered clean moss samples from a designated background site located in Russia's Tver region. Before deployment, the plant material was carefully cleaned, dried, and packed securely into bags for placement along the roadways.

Following the exposure period, the retrieved moss bags underwent comprehensive laboratory analysis using Inductively Coupled Plasma Optical Emission Spectroscopy alongside a direct mercury analyser. The team tested the samples for a total of sixteen different chemical elements, seeking to understand the full spectrum of absorbed matter.

The examined elements included aluminium, barium, cobalt, cadmium, chromium, copper, iron, manganese, nickel, phosphorus, lead, strontium, sulphur, vanadium, zinc, and mercury. The laboratory results revealed that, with the sole exception of phosphorus, the content of every measured element in the exposed moss either matched or exceeded the baseline levels found in the unexposed samples.

This accumulation demonstrated a clear and direct uptake of pollutants from the surrounding roadside air. Researchers noted that these metallic elements typically originate from multiple automotive sources, including vehicle exhaust, the wearing down of tyres and brakes, engine corrosion, and road dust kicked up into the atmosphere by passing vehicles.

Pollution levels captured by the moss varied sharply across the three locations. The most pronounced concentration and uptake of elements was recorded at the Leningradskoye highway, followed sequentially by the Yaroslavskoye and Dmitrovkoye roads. The scientific team linked this clear hierarchy directly to differences in traffic density among the three routes.

Certain elements, specifically aluminium, cobalt, cadmium, manganese, and lead, registered significantly higher concentrations in the moss samples deployed at the Leningradskoye highway compared to the other two thoroughfares. Furthermore, statistical analysis demonstrated that the concentrations of several elements—including aluminium, copper, cobalt, chromium, iron, nickel, and vanadium—fluctuated depending on the physical distance from the road edge.

In general, the concentration of these metals dropped off the further the moss bags were placed from the path of active traffic. This spatial variation further underscored how closely tied the metallic contamination was to proximity to the highway itself.

The research was conducted by a team based at the Department of Nuclear Physics at the Joint Institute for Nuclear Research in Dubna, Russia. The specific investigators involved in the study were Inga Zinicovscaia, Omari Chaligava, Nikita Yushin, Dmitrii Grozdov, Konstantin Vergel, and Pavel Nekhoroshkov.

Based on their findings, the research team concluded that moss biomonitoring serves as an effective and inexpensive tool for tracking traffic-related air pollution. While similar biomonitoring techniques are already widely utilized across various parts of Europe and Asia, this study highlights its specific utility along isolated stretches of highway free from confounding background contamination.

The implications of the study point toward more affordable and accessible methods for monitoring roadside metal pollution in the future. By confirming that moss can reliably absorb and reflect the density of vehicle emissions, tyre wear, and brake wear, the findings offer environmental scientists a practical proxy for assessing air quality near major transportation corridors.