Annual and seasonal variability in high latitude dust deposition, West Greenland

Abstract

High latitude regions (≥ 50 N and ≥ 40 S) are thought to contribute substantially to contemporary global dust emissions which can influence biogeochemical cycling as well as geomorphic, cryospheric and atmospheric processes. However, there are few measurements of the emission or deposition of dust derived from these areas that extend beyond a single event or season. This article reports the deposition of locally-derived dust to an ice-free area of West Greenland over 2 years from 23 traps distributed across five sampling sites. Local dust sources include glacial outwash plains, glacially-derived delta deposits and the reworking of loessic soils. Annual dust deposition is estimated at 37.3 to 93.9 g m À2 for 2017-2018 and 9.74 to 28.4 g m À2 in 2018-2019. This annual variation is driven by high deposition rates observed in spring 2017 of 0.48 g m À2 d À1 compared to the range of 0.03 to 0.07 g m À2 d À1 during the rest of the monitoring period. The high deposition rates in spring 2017 were due to warmer than average conditions and high meltwater sediment supply that delivered large quantities of sediment to local outwash plains in 2016. For other seasons, dust deposition was lower over both autumn-winter periods (0.03 g m À2 d À1 ) than during the spring and summer (0.04-0.07 g m À2 d À1 ). When sediment availability is limited, dust deposition increases with increasing temperature and wind speed.Secondary data from dust-related weather type/observation codes and visibility records were found to be inconsistent with measured dust deposition during the period of study. One possible reason for this is the complex nature of the terrain between the observation and sample sites. The dust deposition rates measured here and the infidelity of the observed dust with secondary data sources reveal the importance of direct quantification of dust processes to accurately constrain the dust cycle at high latitudes.

Grazing and topography control nutrient pools in low Arctic soils of Southwest Greenland

“…While SS17b is located very close to the sandur (Figure 1), at both sites, the estimated dust deposition rates (as mineral matter) are similar (8.94 g m −2 year −1 at SS17b and 9.49 g m −2 year −1 at SS85 in 2018) (van Soest et al, 2022). In this context, it is unclear to what extent the two catchments responded differently to the effects of Little Ice Age (LIA) cooling, which may have re‐set landscape ontogeny and biogeochemical processes (Willemse et al, 2003).…”

“…The two catchments in the present study can be classified as distal in the terminology of Anderson (2007) given their distance from the present ice sheet and their similar age. The differences in soil nutrients between the two sites are also considered in terms of local‐to‐regional drivers, especially the effect of muskox grazing (Olofsson et al, 2001; Post & Høye, 2013), but also dust deposition (van Soest et al, 2022).…”

“…The Kangerlussauq soils are similar to those from arable soils in the Netherlands (average 0.50 [range 0.16-0.92] g P kg À1 ; van der Wal et al, 2007) and grassland soils from England and Wales (averaged 0.94 [range 0.38-1.98] g P kg À1 ; Turner & Haygarth, 2003) even in the absence of fertiliser inputs. The source of the soil P in the Kangerlussuaq area reflects weathering from parent geological material (ancient granodioritic gneiss with ultra-basic intrusions, glacial till) (Hawkings et al, 2016) and via aeolian deposition (van Soest et al, 2022).…”

“…Muskox are very rare but there are occasional reindeer. Both catchments are impacted by dust deposition and investigations suggest that the rates are similar at both locations (van Soest et al, 2022).…”

“…Recent soil‐focused work in the Kangerlussuaq area was reviewed by Anderson (2020), and highlighted the complex and heterogenous nature of soil types and cover in the Kangerlussuaq area, their relationship to local vegetation and hence, ultimately, regional microclimates. However, as well as the role of local landscape morphology (Henkner et al, 2016), there is also the possible impact of local wind erosion (Heindel et al, 2015), dust deposition (van Soest et al, 2022; Willemse et al, 2003), and impacts of grazers (Cahoon et al, 2012).…”