Plumes and blooms – Locally-sourced Fe-rich aeolian mineral dust drives phytoplankton growth off southwest Africa

Dansie, Andrew; Thomas, David S.G.; Wiggs, Giles F.S.; Baddock, Matthew C.; Ashpole, Ian

doi:10.1016/j.scitotenv.2022.154562

Cited by 8 publications

(5 citation statements)

References 61 publications

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“…This is consistent with other studies which have evaluated a range of models on more restricted spatial and vertical scales (Adebiyi and Kok, 2020;Ansmann et al, 2017;O'Sullivan et al, 2020). Incorrect representation of dust size distributions in climate models will result in erroneous dust radiative effects, impacts on clouds, and deposition of nutrients within dust to the ocean and land surfaces (Adebiyi et al, 2023;Kok et al, 2017;Dansie et al, 2022). It is therefore important to understand and improve modelled dust size distributions.…”

Section: Size Distribution Evolutionsupporting

confidence: 86%

Long range transport of coarse mineral dust: an evaluation of the Met Office Unified Model against aircraft observations

Ratcliffe,

Ryder,

Bellouin

et al. 2024

Preprint

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Abstract. Coarse mineral dust particles have been observed much further from the Sahara than expected based on theory. They have different impacts to finer particles on the Earth's radiative budget, and carbon and hydrological cycles, though tend to be under-represented in climate models. We use measurements of the full dust size distribution from aircraft campaigns over the Sahara, Canaries, Cape Verde and Caribbean. We assess the observed and modelled dust size distribution over long-range transport at high vertical resolution using the Met Office Unified Model, which represents dust up to 63.2 μm diameter, greater than most climate models. In the observations, we find that the mass contribution of coarse particles (d>6.32 μm) to total mass is independent of 0.55 μm aerosol optical depth. We show that the model generally replicates the vertical distribution of the total dust mass but transports larger dust particles too low in the atmosphere. Importantly, coarse particles in the model are deposited too quickly, resulting in an underestimation of dust mass that is exacerbated with westwards transport; 20–63 μm dust mass contribution between 2–3.7 km altitude is underestimated by factors of up to 11 at the Sahara, 150 at the Canaries and 340 at Cape Verde. At the Caribbean, there is negligible modelled contribution of d>20 μm particles to total mass, compared to 15 % in the observations. This work adds to the growing body of research that demonstrates the need for a process-based evaluation of climate model dust simulations to identify where improvements could be implemented.

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Section: Size Distribution Evolutionsupporting

confidence: 86%

Long range transport of coarse mineral dust: an evaluation of the Met Office Unified Model against aircraft observations

Ratcliffe,

Ryder,

Bellouin

et al. 2024

Preprint

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“…Microbes residing in seawater, either alive or degraded, can further affect the aerosol solubility by physically attaching to aerosols and hence alter their residence time in the ocean surface. Cell–particle interactions are commonly reported in lakes and coastal regions, but even in remote ocean regions there are indications for such encounters (Held et al 2021; Dansie et al 2022). Cell–particle interactions can strongly affect the particle fate and chemical milieu and subsequently change its solubility and bioavailability.…”

Section: Discussionmentioning

confidence: 99%

Co‐acquisition of mineral‐bound iron and phosphorus by natural Trichodesmium colonies

Shaked

Beer

Wang

et al. 2023

Limnology & Oceanography

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Low iron (Fe) and phosphorus (P) ocean regions are often home to the globally important N 2 -fixing cyanobacterium Trichodesmium spp., which are physiologically adapted to Fe/P co-limitation. Given Trichodesmium's eminent ability to capture particles and the common associations between Fe and P in sediments and aerosols, we hypothesized that mineral bio-dissolution by Trichodesmium spp. may enable them to co-acquire Fe and P. We present a new sensitive assay to determine P uptake from particles, utilizing 33 P-labeled ferrihydrite. To validate the method, we examined single natural Trichodesmium thiebautii colonies in a high-resolution radiotracer ß-imager, identifying strong colony-mineral interactions, efficient removal of external 33 P-labeled ferrihydrite, and elevated 33 P uptake in the colony core. Next, we determined bulk P uptake rates, comparing natural Red Sea colonies and P-limited Trichodesmium erythraeum cultures. Uptake rates by natural and cultured Trichodesmium were similar to P release rates from the mineral, suggesting tight coupling between dissolution and uptake. Finally, synthesizing P-ferrihydrite labeled with either 33 P or 55 Fe, we probed for Fe/P co-extraction by common microbial mineral solubilization pathways. Dissolution rates of ferrihydrite were accelerated by exogenous superoxide and strong Fe-chelator and subsequently enhanced 33 P release and uptake by Trichodesmium. Our method and findings can facilitate further Fe/P co-acquisition studies and highlight the importance of biological mechanisms and microenvironments in controlling bioavailability and nutrient fluxes from particles.

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“…However, the extremely limited ground-based observations of climatic (especially wind power, erosivity) or surface (erodibility) drivers relevant to dust emission at Etosha Pan have prevented further understanding or quantification. Two field studies have sampled sediments from the surface of Etosha Pan to determine the possible influence of dust plume geochemistry and nutrient content on regional terrestrial and marine ecosystems west of the pan (Bhattachan et al, 2015;Dansie et al, 2017Dansie et al, , 2022. However, no other surface or erodibility measurements relevant to aeolian dust emission from Etosha Pan are available in the literature.…”

Section: Etosha Pan Namibiamentioning

confidence: 99%

“…Windblown dust is a major global export from the world's deserts and plays a critical role in the Earth's land‐atmosphere‐ocean‐biosphere system (Shao et al., 2011). It has been shown to have a crucial influence on the radiation balance and climate modulation (Evan et al., 2016; Kok et al., 2017; Li et al., 2004; Schepanski, 2018; Slingo et al., 2006; Zhu et al., 2007), iron fertilization of the ocean (Cassar et al ., 2007; Dansie et al., 2018, 2022; Ito & Kok, 2017; Jickells et al., 2005), long‐distance nutrient transport and soil geochemistry (Bristow et al., 2010; Koren et al ., 2006; Lawrence et al., 2013), and human health (O’Hara et al., 2000; Prospero et al ., 2014; Stafoggia et al., 2016). Yet the complex controls governing the emission of dust and the dynamics of individual dust emission events, which together represent the activity of emissive source areas, remain poorly understood (Bryant, 2013; Bullard, 2010).…”

Section: Introductionmentioning

confidence: 99%

Quantifying Mechanisms of Aeolian Dust Emission: Field Measurements at Etosha Pan, Namibia

et al. 2022

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Plumes and blooms – Locally-sourced Fe-rich aeolian mineral dust drives phytoplankton growth off southwest Africa

Cited by 8 publications

References 61 publications

Long range transport of coarse mineral dust: an evaluation of the Met Office Unified Model against aircraft observations

Long range transport of coarse mineral dust: an evaluation of the Met Office Unified Model against aircraft observations

Co‐acquisition of mineral‐bound iron and phosphorus by natural Trichodesmium colonies

Quantifying Mechanisms of Aeolian Dust Emission: Field Measurements at Etosha Pan, Namibia

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