Bandrés et al. (2025) Chemistry and sources of atmospheric aerosols deposited in the Central Pyrenees in the period 2016–2023, with a focus on African dust events occurred during cold season

Identification

• Journal: Atmospheric Research
• Year: 2025
• Date: 2025-12-12
• Authors: Javier Bandrés, Juan Ignacio López-Moreno, Pedro Salvador, Jorge Pey
• DOI: 10.1016/j.atmosres.2025.108686

Research Groups

• Instituto Pirenaico de Ecología (IPE-CSIC), Zaragoza, Spain
• Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain

Short Summary

This study geochemically characterizes and identifies primary sources of atmospheric aerosols deposited in the Central Pyrenees from 2016 to 2023, revealing that African dust accounts for 45% of total annual deposition, with intense cold-season events significantly impacting the cryosphere.

Objective

• To characterize the geochemical composition and identify primary sources of atmospheric aerosols deposited in the Ordesa y Monte Perdido National Park (Central Pyrenees).
• To analyze the temporal variability of aerosol sources, particularly focusing on the impact of African dust events during the cold season on the surrounding cryosphere.

Study Configuration

• Spatial Scale: Ordesa y Monte Perdido National Park (PNOMP), Central Pyrenees, Spain (42°39′19″ N, 0°5′57″ O, 1206 m above sea level).
• Temporal Scale: June 2016 to May 2023 (7 years of data collection). Sampling frequency: bi-weekly for the first year, then monthly.

Methodology and Data

• Models used:
  • Positive Matrix Factorization (PMF) v5.0 (EPA PMF) for source apportionment.
  • HYSPLIT model for air mass back-trajectories (120 hours duration, 750 m, 1500 m, and 2500 m above ground level).
  • k-means cluster analysis (using the 'openair' R package) for back-trajectories.
• Data sources:
  • Total aerosol deposition monitoring (98 samples collected using an opaque polyethylene container and funnel).
  • Laboratory chemical analysis:
    • Soluble fraction: Ionic Chromatography (for anions: HCO3−, NO3−, NO2−, SO42−, Cl−; and cations: NH4+, Ca2+, Mg2+, K+, Na+), Continuous Flow Analyzer (for cations and HCO3−).
    • Insoluble fraction: Acidic digestion (HF:HNO3:HClO4) followed by Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) for major (Al, Ca, Fe, K, Mg, Na, Mn, Sr, Ti) and trace elements (Ag, As, Ba, Be, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sb, Se, Th, Tl, U, V, Zn).
    • Organic Carbon (OC) and Elemental Carbon (EC) determined by thermo-optical SUNSET analyzer (EUSAAR_2 protocol).
  • Meteorological data: NCEP/NCAR Reanalysis dataset (daily geopotential height at 850 hPa level).
  • Aerosol maps and satellite imagery for identifying dust events.

Main Results

• African dust is the dominant source of atmospheric deposition in the Central Pyrenees, contributing an annual average of 12.8 g m−2 yr−1, which accounts for 45% of the total deposition over the 2016–2023 period.
• Air mass back-trajectory analysis indicated that between 10.3% and 19.5% of air masses originated from North Africa.
• The total annual atmospheric deposition averaged 26.5 g m−2, with soluble and insoluble fractions almost equally distributed (55% vs. 45%). Mineral components (soluble and insoluble) constituted approximately 75% of the total deposited aerosols.
• Intense African dust deposition events predominantly occurred during the cold season (November–April), with individual events depositing between 3.7 g m−2 and 27.2 g m−2 of material. The February 2021 event recorded the highest deposition at 27.2 g m−2.
• PMF analysis identified seven distinct sources: African Dust Polluted 1, African Dust, African Dust Polluted 2, Regional Dust, Regional Pollution (including road transport), Aged Marine Aerosol, and Biomass Burning.
• African dust-related factors (AF-1 Polluted, AF, AF-2 Polluted) collectively contributed 60% to 90% of the total mass during large dust events.
• Elemental ratios suggest that eastern North African source regions (PSA LAM/PSA 1 + PSA 3) contributed 75% of the total dust load, while western regions (PSA WAC/PSA 2) contributed 25%.
• Anthropogenic species like sulfate showed a decreasing trend since 2020, while anomalous Cl−/Na+ ratios indicated industrial HCl emissions from a nearby chlor-alkali industry.

Contributions

• Provides the first comprehensive 7-year dataset of monthly aerosol deposition in a high-mountain National Park in the Pyrenees, filling a significant gap in long-term atmospheric deposition studies for such environments.
• Successfully applies the EPA PMF model to distinguish three distinct African dust sources based on compositional variations and elemental ratios, linking them to specific North African source regions (eastern vs. western).
• Quantifies the substantial contribution of African dust to total atmospheric deposition in the Central Pyrenees and highlights its critical impact on the cryosphere, especially during intense cold-season events.
• Demonstrates the complex interplay between atmospheric transport, aerosol composition, and snowpack dynamics in high-mountain environments under ongoing climate change, emphasizing the need for sustained monitoring and cross-disciplinary research.
• Identifies and quantifies the influence of both natural (African dust, regional dust, marine aerosol, biomass burning) and anthropogenic (regional pollution, industrial emissions) sources on aerosol composition and deposition in the region.

Funding

• MARGISNOW project (PID2021-124220OB-100) funded by the Spanish Ministry of Science and Innovation.
• POSAHPI actions (AEI, PID2019-108101RB-I00, PID2022-143146OB-I00).
• ASAH-AS (OAPN 2021, reference 2799/2021).
• SNOWDUST (AEI, TED2021-130114B-I00).

Citation

@article{Bandrés2025Chemistry,
  author = {Bandrés, Javier and López-Moreno, Juan Ignacio and Salvador, Pedro and Pey, Jorge},
  title = {Chemistry and sources of atmospheric aerosols deposited in the Central Pyrenees in the period 2016–2023, with a focus on African dust events occurred during cold season},
  journal = {Atmospheric Research},
  year = {2025},
  doi = {10.1016/j.atmosres.2025.108686},
  url = {https://doi.org/10.1016/j.atmosres.2025.108686}
}