# Traditional and low-cost technical approaches for investigating greenhouse gases and particulate matter distribution along an urban-to-rural transect (Greve River Basin, Central Italy)

## TL;DR

This study uses low-cost and traditional methods to track greenhouse gases and particulate matter in an urban-to-rural area in Italy.

## Contribution

The study introduces a combination of low-cost sensors and mobile monitoring to track air pollutants with high spatiotemporal resolution.

## Key findings

- High CO2 and CH4 concentrations downstream are linked to vehicular traffic based on isotopic signatures.
- Pollutant levels peak in the early morning due to stable atmospheric conditions and decrease during the day with turbulence.
- PM2.5 distribution is influenced by wind speed and rainfall, similar to gaseous pollutants.

## Abstract

Human activities, largely tied to fossil fuels and intensive agriculture, emit massive amounts of climate-altering species and harmful pollutants into the atmosphere that affect soil, ecosystems, and water. Air quality monitoring is crucial to minimize harmful effects and protect human and environmental health. The Greve River basin (Tuscany, central Italy) represents an excellent example of an ecosystem affected by various anthropogenic air contaminants. The upstream areas are predominantly rural, while the downstream zones are characterized by urban and industrial development. Air pollutants throughout the basin were measured adopting two strategies: (i) fixed monitoring at five sites using multiparametric stations equipped with low-cost sensors for CO2, CH4, and PM2.5 concentrations; (ii) measurements along a transect using a mobile monitoring station equipped with a Picarro G2201-i analyzer for the determination of CO2 and CH4 concentrations and 13C/12C values of the two gases. Results revealed relatively high CO2 and CH4 concentrations downstream, mainly due to vehicular traffic based on the isotopic signature. The temporal and spatial distribution of the contaminants mirrored the evolution of the Planetary Boundary Layer, with peak concentrations in the early morning due to stable atmospheric conditions, and contaminant dilution due to air turbulence during the daytime. Particulate (PM2.5) distribution showed a trend similar to gaseous pollutants, being strongly dependent on wind speed and rainfall events. The high spatiotemporal resolution of data acquisition provided by the low-cost stations for air quality measurements represents an important advance for developing monitoring strategies, complementing the traditional instrumentation commonly used by agencies.

The online version contains supplementary material available at 10.1007/s10653-025-02456-2.