Concentrations of Select Metals and Metalloids in Air in ’A’ą̈y Chù’ Valley Mineral Dust Spring/Summer 2021

Total Suspended Material (TSP), PM10 and PM2.5 samples were collected in the ’A’ą̈y Chù’ Valley in Kluane National Park, Yukon, Canada from early June to early July 2021 at 3.3 and 6.3 m above the ground. The GPS coordinates for the sample site are 60°59'55.25"N, 138°31'24.05"W. Samples were then analyzed for metal(loid) concentrations using ICP-MS. Results are corrected for recovery and presented along with Yukon workplace airborne metal(loid) 8-hour exposure standards and Ontario Ambient 24-hour standards.

Sampling procedure: PM sampling began on June 4th and ended on July 2nd, 2021. PM sampling was conducted using a set of four ARA N-FRM Samplers (ARA Instruments) positioned in pairs at 3.3 m and 6.3 m above the ground, with respect to the height of the sampling head inlets. The samplers were set in pairs to allow for simultaneous sampling at a given height of different PM size classes, Total Suspended Particles (TSP), PM10, and PM2.5. PM sampling was conducted on nearly a daily basis for TSP and PM10 samples, using an approximate collection time of 24 hours, whereas a 48-hour collection time was used for PM2.5 samples to obtain greater masses of PM2.5 for improved quantitation of trace elements. A flow rate of 16.7 L min−1 was used for samples destined for metal(loid)s analysis. All PM sampled this way was either collected on Teflon (PALL Corporation, Teflo, 2.0 µm pore size, 47 mm diameter) or Quartz fiber (Whatman™, Grade QMA, 47 mm diameter) filters. Filters were weighed and pre-weighed using a microbalance (VWR, VWR-21XC, readability 1 µg). Quality control procedures for gravimetric measurements were adapted from the US-EPA’s Quality Assurance Guidance Document 2.12 for Monitoring PM2.5 in Ambient Air Using Designated Reference or Class 1 Equivalent Methods (Us-Epa, 2016). As such, at least one lab blank and one field blank filter was reserved for every 10 filters used for sampling. The filters were conditioned in the weighing room for at least 24 hours prior to their weighing or pre-weighing.