A Synoptic survey of major solutes, metals, and volatile organic compounds in high-latitude maritime snowpack near the trans-Alaska pipeline terminal, Valdez, Alaska

The chemical constituents within a snowpack can provide information about the atmosphere through which the snow was deposited. Valdez is located in south-central Alaska and has a high-latitude maritime climate, with annual snowfall typically exceeding 8 m within the city limits. Valdez is also the termination point of the Trans-Alaska Pipeline System, where tankers are loaded with crude oil from the North Slope. Integrated samples of the top 1 m of snow were collected at 7 sites near Valdez and analyzed for major solutes, mercury, lead, and volatile organic compounds (VOCs). For comparison, sites were also sampled near Juneau, Alaska, which has a similar climate but no petroleum transport infrastructure.

Major solute chemistry at all sites was dominated by chloride, and was consistent with a marine air mass source of ions in precipitation. Sulfate levels in Valdez were typically on the order of 10 µeq/L. Other major solute levels were low in Valdez and Juneau. Mercury and lead levels were below detection limits for all sites, with the exception of trace concentrations of lead (< 0.4 µg/L) reported at two Valdez locations. Volatile organics were present at all Valdez locations, while VOCs were not detected in Juneau. Ethylbenzene levels ranged from 1.0 to 1.1 µg/L, xylenes ranged in concentration from 3.4 to 4.5 µg/L, and tri-substituted benzenes ranged up to 2.1 µg/L, similar to levels documented previously in urban locations. Furthermore, the VOC fraction of total organic carbon decreased with increasing distance from the pipeline terminal suggesting that this facility may be a source of VOCs found in the seasonal snowcover.

Hexagonal-plate ice crystal pictured above used by permission from SnowCrystals.com