Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
Emerging Mineral Dust Source in ’A’ą̈y Chù’ Valley, Yukon, Canada Poses Potential Health Risk via Exposure to Metal and Metalloids Enriched in PM10 and PM2.5 Size Fractions
Arnold Ross Downey,Alisée Dourlent,Daniel Bellamy,James King,and Patrick Lewis Hayes
Abstract. The ’A’ą̈y Chù’ Valley in Kluane National Park, Yukon, Canada has undergone significant hydrological change in the past decade due to climate-driven glacial recession. This has reverted the ’A’ą̈y Chù’ to a major source of sediment-derived mineral dust, representing an environmental change for the region. Mineral dust influences climatic radiative forcing and impacts human health, both of which depend on its concentration, size distribution, and composition. This work discusses results from a field campaign conducted in the ’A’ą̈y Chù’ Valley in 2021 aimed at understanding and quantifying these parameters, with comparison to a previous campaign in the same location to evaluate the evolution of the dust emissions between 2018 and 2021. An optical particle counter (OPC) instrument measured a mean volume diameter of airborne dust of 4.43 µm at 3.3 m above ground, with Coulter Counter measurements being used for comparison and validation. The concentration of many metal(loid)s in the dust were also studied: Al, Ag, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Ni, Pb, Rb, Tl, U, V, and Zn. It was found that 24-hour ambient air quality criteria for exposure to several metal(loid)s were surpassed. Significant enrichment of several metal(loid)s was observed for both the PM10 and PM2.5 size fractions relative to the Total Suspended Material (TSP) fraction of the mineral dust. This suggests that the mineral dust in the ’A’ą̈y Chù’ Valley possesses compounding characteristics that are detrimental to human health due to exposure to potentially toxic metal(loid) concentrations.
Received: 18 Jul 2025 – Discussion started: 14 Aug 2025
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This study investigates the emergence of a high-latitude mineral dust source in the ’A’äy Chù’ Valley, Yukon, Canada, following climate-driven glacial recession. The authors focus on the size distribution, elemental composition, and health implications of particulate matter (PM), particularly PM₁₀ and PM₂.₅, enriched with PTEs. The work builds on previous campaigns and expands the scope of elemental analysis. The study addresses a newly intensified dust source in a high-latitude region, which is underrepresented in global dust budgets but disproportionately affects snow albedo and local air quality, linking climate change, glacial recession, and public health. Dual instrumentation (Optical Particle Counter and Coulter Counter) provides cross-validation of particle size distributions. Elemental analysis is well-detailed, including digestion protocols, calibration, and recovery corrections. The study also includes some diurnal variation analysis and comparisons with WHO and Ontario air quality standards.
The study is a nice case study in one valley, it would be interesting to see how the authors would scale up these implications to the wider regional impacts (is this just a health impact in one valley?). how many similar sites have emerged due to glacial recession. Can this data be reflected in dispersion models to elucidate local / regional impacts.
Air quality standards are normally considered for urban and industrial dust sources – do these natural source dusts contain materials that are similarly bioaccessible in e.g. oral or lung fluids.
Minor comments -
L114 – check if ‘Mcmurry’ should be ‘McMurry’. (again at L125 Mctainsh – best check all Scottish names cited).
L275 Typo - ‘respectively.(World Health Organization, 2021)’
L346 Typo ‘and 1.68.(Bachelder et al., 2020; Mukherjee, 2013; Smart and Willis, 1967)’
Fig. 8 – check the units of number, SA and volume, seems odd to me (not an atmospheric scientist), but they don’t match Table1 either.
Table 2 – why is Variance of distribution in brackets
L389 – ‘Shilts et al.’ needs a date.
L447 Typo - basis.(Human Toxicology and Air Standards Section, 2020)
Table 3 - enrichment of PTEs in the fine fraction material is commonly reported – it would be good to see the total enrichment versus the parent material (sediments) so that it could be potentially be predicted the relationship between bulk sediment concentrations and PM concentrations (measurement of sediment concentrations is much easier and much more commonly collected than PM concentrations).
Concentrations of Select Metals and Metalloids in Air in ’A’ą̈y Chù’ Valley Mineral Dust Spring/Summer 2021Arnold Ross Downey http://dx.doi.org/10.5683/SP3/Y4CTDC
Diurnal Statistics for Temperature, Relative Humidity, Wind Speed, PM10, and PM2.5 Concentrations at ’A’ą̈y Chù’ Valley in Kluane National Park, Yukon, Canada for June 2021Arnold Ross Downey http://dx.doi.org/10.5683/SP3/1WHR3P
Raw Optical Particle Counter (OPC) Data for 3.3 and 6.3 meters off ground in ’A’ą̈y Chù’ Valley in Yukon, Canada Late Spring Early Summer 2021Arnold Ross Downey http://dx.doi.org/10.5683/SP3/FKSRWL
Arnold Ross Downey,Alisée Dourlent,Daniel Bellamy,James King,and Patrick Lewis Hayes
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We report findings from a field campaign carried out in the ’A’ą̈y Chù’ Valley in Kluane National Park, Yukon. Direct sampling of a major mineral dust source for airborne particles of different size fractions was conducted, along with continuous measurements of particle size distributions and concentrations. Subsequently, mineral dust samples were analyzed for total concentrations of many metals and metalloids, revealing distinct trends in their concentrations with particle size.
We report findings from a field campaign carried out in the ’A’ą̈y Chù’ Valley in Kluane...
This study investigates the emergence of a high-latitude mineral dust source in the ’A’äy Chù’ Valley, Yukon, Canada, following climate-driven glacial recession. The authors focus on the size distribution, elemental composition, and health implications of particulate matter (PM), particularly PM₁₀ and PM₂.₅, enriched with PTEs. The work builds on previous campaigns and expands the scope of elemental analysis. The study addresses a newly intensified dust source in a high-latitude region, which is underrepresented in global dust budgets but disproportionately affects snow albedo and local air quality, linking climate change, glacial recession, and public health. Dual instrumentation (Optical Particle Counter and Coulter Counter) provides cross-validation of particle size distributions. Elemental analysis is well-detailed, including digestion protocols, calibration, and recovery corrections. The study also includes some diurnal variation analysis and comparisons with WHO and Ontario air quality standards.
The study is a nice case study in one valley, it would be interesting to see how the authors would scale up these implications to the wider regional impacts (is this just a health impact in one valley?). how many similar sites have emerged due to glacial recession. Can this data be reflected in dispersion models to elucidate local / regional impacts.
Air quality standards are normally considered for urban and industrial dust sources – do these natural source dusts contain materials that are similarly bioaccessible in e.g. oral or lung fluids.
Minor comments -
L114 – check if ‘Mcmurry’ should be ‘McMurry’. (again at L125 Mctainsh – best check all Scottish names cited).
L275 Typo - ‘respectively.(World Health Organization, 2021)’
L346 Typo ‘and 1.68.(Bachelder et al., 2020; Mukherjee, 2013; Smart and Willis, 1967)’
Fig. 8 – check the units of number, SA and volume, seems odd to me (not an atmospheric scientist), but they don’t match Table1 either.
Table 2 – why is Variance of distribution in brackets
L389 – ‘Shilts et al.’ needs a date.
L447 Typo - basis.(Human Toxicology and Air Standards Section, 2020)
Table 3 - enrichment of PTEs in the fine fraction material is commonly reported – it would be good to see the total enrichment versus the parent material (sediments) so that it could be potentially be predicted the relationship between bulk sediment concentrations and PM concentrations (measurement of sediment concentrations is much easier and much more commonly collected than PM concentrations).