Trends in spatial patterns of heavy metal deposition on national park service lands along the Red Dog Mine haul road, Alaska, 2001–2006

Abstract

Spatial patterns of Zn, Pb and Cd deposition in Cape Krusenstern National Monument (CAKR), Alaska, adjacent to the Red Dog Mine haul road, were characterized in 2001 and 2006 using Hylocomium moss tissue as a biomonitor. Elevated concentrations of Cd, Pb, and Zn in moss tissue decreased logarithmically away from the haul road and the marine port. The metals concentrations in the two years were compared using Bayesian posterior predictions on a new sampling grid to which both data sets were fit. Posterior predictions were simulated 200 times both on a coarse grid of 2,357 points and by distance-based strata including subsets of these points. Compared to 2001, Zn and Pb concentrations in 2006 were 31 to 54% lower in the 3 sampling strata closest to the haul road (0–100, 100–2000 and 2000–4000 m). Pb decreased by 40% in the stratum 4,000–5,000 m from the haul road. Cd decreased significantly by 38% immediately adjacent to the road (0–100m), had an 89% probability of a small decrease 100–2000 m from the road, and showed moderate probabilities (56–71%) for increase at greater distances. There was no significant change over time (with probabilities all ≤ 85%) for any of the 3 elements in more distant reference areas (40–60 km). As in 2001, elemental concentrations in 2006 were higher on the north side of the road. Reductions in deposition have followed a large investment in infrastructure to control fugitive dust escapement at the mine and port sites, operational controls, and road dust mitigation. Fugitive dust escapement, while much reduced, is still resulting in elevated concentrations of Zn, Pb and Cd out to 5,000 m from the haul road. Zn and Pb levels were slightly above arctic baseline values in southern CAKR reference areas.

Heavy metals in the Arctic: Distribution and enrichment of five metals in Alaskan soils

“…Concentrations of As, Cr, Hg, Ni, and Pb in mine-impacted areas of Alaska were especially elevated (Fig 2), likely due to heavy metal air pollution from mines and subsequent wet/dry deposition onto soils [10,53]. However, soils with metals concentrations that exceed average values from the contiguous United States are distributed across the study region and are not isolated to mine-impacted sites or sites with close proximity to sources of anthropogenic contamination (S2 Fig).…”

“…Permafrost thaw not only exacerbates the decomposition and liberation of carbon (C) to the atmosphere [4] and adjacent water bodies [5], but heavy metals stored in permafrost can also be released by thaw and transported into surface waters [6,7]. Heavy metals are present in Arctic soils due to weathering [8], atmospheric deposition [9], and anthropogenic activities including mining and/or smelting [10,11]. In permafrostaffected landscapes, metals may accumulate in frozen soils.…”

Heavy metals in moss guide environmental justice investigation: a case study using community science in Seattle, WA, USA

“…To inexpensively fill these gaps for heavy metals, scientists commonly measure concentrations in moss or lichen tissue (hereafter, ‘bioindicators;’ e.g. Giordano et al 2009, Massimi et al 2019, Neitlich et al 2017). Without roots or a protective outer cuticle, moss and lichens absorb water, nutrients, and co-occurring toxics from the atmosphere, making them a valuable first-pass screening tool in urban areas (e.g.…”

Heavy metals in moss guide environmental justice investigation: A case study using community science in Seattle, WA, USA

“…To inexpensively fill these gaps for heavy metals, scientists commonly measure concentrations in moss or lichen tissue (hereafter, “bioindicators”; e.g., Giordano et al, 2009; Massimi et al, 2019; Neitlich et al, 2017). Without roots or a protective outer cuticle, moss and lichens absorb water, nutrients, and co‐occurring toxics from the atmosphere, making them a valuable first‐pass screening tool in urban areas (e.g., Donovan et al, 2016; Messager et al, 2021).…”