Iron‐rich nanoparticles formed by aeolian abrasion of desert dune sand

Abstract

[1] Iron-rich nanoparticles in aeolian mineral dust are of considerable importance to biogeochemical cycles. A major determinant of the chemical characteristics of nanoparticles is the parent sediment they are sourced from. The abrasion of dune sand has previously been shown to produce coarse dust (>1 m) during the occurrence of aeolian saltation. In this study, Australian red dune sands were laboratory abraded and emission of particles 18-414 nm was observed throughout the experiment duration ($1 h). The mean size of particles was 130 nm at the start of the test, but this gradually decreased to 110 nm at the end. The number concentration of particles approximately trebled over the course of the experiment with results suggesting that collisions between mobile sand grains led to the production of new nanosized particles over time. Chemical analysis revealed that these nanoparticles were highly abundant in iron, with some aluminium present. This chemical composition suggests that nanoparticles are produced from the clay coatings surrounding the parent sand grains. The study shows that abrasion from saltation occurring in Australian dune sands can release iron-rich nanoparticles, making them available for downwind transport during blowing dust events.

Iron oxide minerals in dust-source sediments from the Bodélé Depression, Chad: Implications for radiative properties and Fe bioavailability of dust plumes from the Sahara

“…Such occurrences have been observed in far-traveled dust in Australia (Reynolds et al, 2014a) and from Asia (Jeong and Nousiainen, 2014). These observations complement experimental results by Baddock et al (2013) that inferred production of iron-rich nanoparticles from clay coatings on larger particles by abrasion from saltation during dust-producing wind events.…”

Biogeochemistry of dust sources in Southern Africa

“…Moreover, the interdune sediments in Bokspits and Struizendam are comparatively less susceptible to aeolian activity e and therefore have been less depleted of iron e relative to the pan sediments. The potential for dunes prone to wind erosion to emit iron-rich particles (<10 mm) is large (e.g., Bullard and White, 2005;Bullard et al, 2007;Baddock et al, 2013). Therefore, in absence of aeolian abrasion iron oxides found in Kalahari interdune sediments are bound in the coarse fraction.…”

Small-scaled lateral variations of an organic-rich formation in a ramp-type depositional environment (the Late Jurassic of the Boulonnais, France): impact of the clastic supply

“…The larger the transgression, the larger the volume of reworked and remobilized sediments, which will impact the possible release of iron, coating fine particles; -the flux of river-borne (Severmann et al, 2010) or airborne (e.g., Baddock et al, 2013;Buck et al, 2013) ironcoated particles; -the flux of OM possibly associated with reactive iron (e.g., Barber et al, 2014;Bressac and Huieu, 2013;Krachler et al, 2012;Shigemitsu et al, 2013). Notably, Krachler et al (2012) indicated that peatland-derived iron-bearing lignin particles may have a sufficiently long half-life in ocean water to sustain iron concentration in extended regions of the ocean; -the offshore discharge of anoxic ground waters may generate O 2 -undersaturated bottom water masses that can be advected into nearshore waters (Peterson et al, 2016).…”