Quantification of iron-rich volcanogenic dust emissions and deposition over the ocean from Icelandic dust sources

Abstract

Abstract. Iceland has extremely active dust sources that result in large-scale emissions and deposition on land and at sea. The dust has a volcanogenic origin of basaltic composition with about 10 % Fe content. We used two independent methods to quantify dust emission from Iceland and dust deposition at sea. Firstly, the aerial extent (map) of deposition on land was extended to ocean areas around Iceland. Secondly, surveys of the number of dust events over the past decades and calculations of emissions and sea deposition for the dust storms were made. The results show that total emissions range from 30.5 (dust-event-based calculation) to 40.1 million t yr −1 (map calculation), which places Iceland among the most active dust sources on Earth. Ocean deposition ranges between 5.5 (dust event calculations) and 13.8 million tons (map calculation). Calculated iron deposition from Icelandic dust ranges between 0.567 and 1.4 million tons, which are distributed over wide areas (> 370 000 km 2 ) and consist of fine reactive volcanic materials. The paper provides the first quantitative estimate of total dust emissions and oceanic deposition from Iceland. Iron is a limiting nutrient for primary production in the oceans around Iceland, and the dust is likely to affect Fe levels in Icelandic ocean waters.

Temporal and spatial variability of Icelandic dust emissions and atmospheric transport

“…This is similar to the FLEX-DUST estimate for dust emissions in Iceland in years 2010 through 2012 in global simulations (4.8 Tg; Groot Zwaaftink et al, 2016). Dust emission rates are an order of magnitude lower than previous estimates of dust emission rates (30.5 to 40.1 Tg annually) presented by Arnalds et al (2014). Their estimate includes dust spikes and redistribution in relation to volcanic events and glacial outbursts and is in part based on deposition rates (soil metadata and tephrochronology).…”

“…Their estimate includes dust spikes and redistribution in relation to volcanic events and glacial outbursts and is in part based on deposition rates (soil metadata and tephrochronology). Also larger particles are included in estimates of Arnalds et al (2014), most of which would be deposited in the near vicinity of their sources. Other possible causes for this large difference are the large uncertainty related to extrapolation of visibility and storm frequency observations to dust concentration and emission estimates.…”

“…Transport pathways from two main Icelandic dust source regions have been studied (Baddock et al, 2017) and qualitatively describe regions that may be affected. Dust emission amounts from Iceland were estimated by Arnalds et al (2014). Based on storm frequencies, deposition rates, visibility observations and satellite images they concluded that 30.5 to 40.1 Tg dust is emitted annually in Iceland.…”

Insulation effects of Icelandic dust and volcanic ash on snow and ice

“…This value is much lower than the mean deposition of 400 g m −2 years −1 suggested by Arnalds et al (2014). As the results of the Roof 2015 experiments show for both grain sizes that very small amounts (1-2 mm or smaller) of ash (or dust) deposition are enough to enhance melt, it is possible that the small amounts of dust or ash deposited on Vatnajökull have a comparable melt effect.…”

The Spatial Variation of Dust Particulate Matter Concentrations during Two Icelandic Dust Storms in 2015

“…This event lasted for about 12 h and the total flux from the source is estimated to be about 280,000 tonnes. Both events can thus be characterized as medium-sized (e.g., [22,37] The distance of the measurements from the dust sources was <100 km. The source material contains extremely fine particles.…”