Atmospheric Transport and Deposition of Mineral Dust to the Ocean: Implications for Research Needs

Abstract

This paper reviews our knowledge of the measurement and modeling of mineral dust emissions to the atmosphere, its transport and deposition to the ocean, the release of iron from the dust into seawater, and the possible impact of that nutrient on marine biogeochemistry and climate. Of particular concern is our poor understanding of the mechanisms and quantities of dust deposition as well as the extent of iron solubilization from the dust once it enters the ocean. Model estimates of dust deposition in remote oceanic regions vary by more than a factor of 10. The fraction of the iron in dust that is available for use by marine phytoplankton is still highly uncertain. There is an urgent need for a long-term marine atmospheric surface measurement network, spread across all oceans. Because the southern ocean is characterized by large areas with high nitrate but low chlorophyll surface concentrations, that region is particularly sensitive to the input of dust and iron. Data from this region would be valuable, particularly at sites downwind from known dust source areas in South America, Australia, and South Africa. Coordinated field experiments involving both atmospheric and marine measurements are recommended to address the complex and interlinked processes and role of dust/Fe fertilization on marine biogeochemistry and climate.

Estimating chemical composition of atmospheric deposition fluxes from mineral insoluble particles deposition collected in the western Mediterranean region

“…However, due to the high temporal variability of desert dust events transported over the Mediterranean Basin, it is difficult to conclude much from a 1-year data set of the chemical elements associated with dust. To do that, a long-term and large-scale deposition sampling network is required (Schulz et al, 2012). In order to obtain a long timeseries of deposition mass fluxes at several sampling sites, a CARAGA (Collecteur Automatique de Retombées Atmosphériques insolubles à Grande Autonomie) collector has been developed (Laurent et al, 2015) and implemented at five sites in the western Mediterranean region (Vincent et al, 2016).…”

A process-based evaluation of dust-emitting winds in the CMIP5 simulation of HadGEM2-ES

“…Further impacts of dust include the disruption of air and road traffic due to reduced visibility and solar energy production due to suspended or deposited dust. Mineral dust also has fertilizing effects on terrestrial and marine ecosystems near and far away from dust sources (Okin et al 2004;Jickells et al 2005;Mahowald et al 2005;Shao et al 2011;Schulz et al 2012). The major source region for mineral dust on Earth is North Africa, from where it can be transported across the Atlantic and Mediterranean basins (e.g.…”

Evolving research directions in Surface Ocean - Lower Atmosphere (SOLAS) science

“…Systematic measurements are required of atmospheric deposition and nutrients in the surface mixed layer in regions where atmospheric supply plays an important role, [99] as in LNLC (low-nutrient low-chlorophyll) regions (C. Guieu et al, unpubl. data) such as the South-west and North-east Pacific and Mediterranean Sea.…”

“…In addition, methodological intercalibration, sample sharing, common reference materials and standardisation of techniques are required to ensure global coherence and quality control. Linking time-series studies of aerosol composition with oceanic time-series data [99] is valuable for constraining the response of the marine ecosystem to deposition events. In addressing these goals, there is considerable mutual interest and benefit of collaborative research with the ocean-derived aerosol strategy (see section above), GESAMP [90] and the GEOTRACES project.…”