Spatiotemporal Assessment of Ions and Total Carbon in Atmospheric Particulate Matter in the Distrito Federal, Central Brazil

Introduction

We characterized PM₁₀ in the Distrito Federal, Central Brazil—a region with agricultural areas, neighboring the Cerrado and biomass burning zones—to identify potential emission sources. We quantified the ions (Li⁺, Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺, F⁻, Cl⁻, NO₃⁻, PO₄³⁻, and SO₄²⁻) and total carbon (TC) in PM₁₀ during the dry and rainy seasons, between March 2022 and July 2024, across three distinct areas: Fercal (cement industry), Rodoviária (urban bus station), and Zoo (background area).

Methodology

A total of 114 samples were collected using High-Vol samplers (1 m³/min/24h of flow) with a sampling frequency of one 24 h sample per day. TC was determined via an Analytik Jena Multi N/C 3100 analyzer, and ions were quantified using ion chromatography.

Results

The highest average PM₁₀ concentrations occurred during the dry season in Fercal (86.29 ± 56.18 μg/m³) and Rodoviária (48.14 ± 17.97 μg /m³), frequently exceeding WHO guidelines of 50 μg/m³ in 69% and 40% of the samples, respectively. Fercal also exhibited the highest TC and ionic concentrations. During the dry season, the decreasing orders of ions (in ng/m³) were as follows: Ca²⁺ > SO₄^2- > Cl^- > Na⁺ > NO₃^- > K⁺ > Mg²⁺ for Fercal and Cl^- > Ca²⁺ > SO₄^2- > NO₃^- > Na⁺ > Mg²⁺ > K⁺ for Rodoviária. The NO₃⁻/SO₄²⁻ ratio < 1 indicated a prevalence of stationary sources in Fercal, whereas NO₃⁻/SO₄²⁻ ratio > 1 indicated a prevalence of mobile sources in Rodoviária and Zoo.

Conclusion

Air pollution in these regions is highly driven by vehicular traffic, wildfires, the cement industry, and agriculture. These findings underscore the critical need for stricter anthropogenic emission controls, wildfire management, and continuous monitoring to mitigate health and environmental impacts.

Acknowledgments

The authors acknowledge FAP-DF No. 00193-00002040/2023-3 for financial support, IBRAM for providing the samples, and the Research Group ProPAGA of CNPq.