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Rapid releases of metal salts and nutrients following the deposition of volcanic ash into aqueous environments

Rapid releases of metal salts and nutrients following the deposition of volcanic ash into aqueous environments
Rapid releases of metal salts and nutrients following the deposition of volcanic ash into aqueous environments
Deposition of volcanic ash into aqueous environments leads to dissolution of adsorbed metal salts and aerosols, increasing the bioavailability of key nutrients. Volcanogenic fertilization events could increase marine primary productivity, leading to a drawdown of atmospheric CO2. Here we conduct flow-through experiments on unhydrated volcanic ash samples from a variety of locations and sources, measuring the concentrations and fluxes of elements into de-ionized water and two contrasting ocean surface waters. Comparisons of element fluxes show that dissolution of adsorbed surface salts and aerosols dominates over glass dissolution, even in sustained low pH conditions. These surface ash-leachates appear unstable, decaying in situ even if kept unhydrated. Volcanic ash from recent eruptions is shown to have a large fertilization potential in both fresh and saline water. Fluorine concentrations are integral to bulk dissolution rates and samples with high F concentrations display elevated fluxes of some nutrients, particularly Fe, Si, and P. Bio-limiting micronutrients are released in large quantities, suggesting that subsequent biological growth will be limited by macronutrient availability. Importantly, acidification of surface waters and high fluxes of toxic elements highlights the potential of volcanic ash-leachates to poison aqueous environments. In particular, large pH changes can cause undersaturation of CaCO3 polymorphs, damaging populations of calcifying organisms. Deposition of volcanic ash can both fertilize and/or poison aqueous environments, causing significant changes to surface water chemistry and biogeochemical cycles.

0016-7037
3661-3680
Jones, Morgan T.
cf1c7a87-0578-4e4b-8708-a22a5b9e7df4
Gislason, Sigurður R.
383711b4-6cfe-421a-9a60-e4879a948e54
Jones, Morgan T.
cf1c7a87-0578-4e4b-8708-a22a5b9e7df4
Gislason, Sigurður R.
383711b4-6cfe-421a-9a60-e4879a948e54

Jones, Morgan T. and Gislason, Sigurður R. (2008) Rapid releases of metal salts and nutrients following the deposition of volcanic ash into aqueous environments. Geochimica et Cosmochimica Acta, 72 (15), 3661-3680. (doi:10.1016/j.gca.2008.05.030).

Record type: Article

Abstract

Deposition of volcanic ash into aqueous environments leads to dissolution of adsorbed metal salts and aerosols, increasing the bioavailability of key nutrients. Volcanogenic fertilization events could increase marine primary productivity, leading to a drawdown of atmospheric CO2. Here we conduct flow-through experiments on unhydrated volcanic ash samples from a variety of locations and sources, measuring the concentrations and fluxes of elements into de-ionized water and two contrasting ocean surface waters. Comparisons of element fluxes show that dissolution of adsorbed surface salts and aerosols dominates over glass dissolution, even in sustained low pH conditions. These surface ash-leachates appear unstable, decaying in situ even if kept unhydrated. Volcanic ash from recent eruptions is shown to have a large fertilization potential in both fresh and saline water. Fluorine concentrations are integral to bulk dissolution rates and samples with high F concentrations display elevated fluxes of some nutrients, particularly Fe, Si, and P. Bio-limiting micronutrients are released in large quantities, suggesting that subsequent biological growth will be limited by macronutrient availability. Importantly, acidification of surface waters and high fluxes of toxic elements highlights the potential of volcanic ash-leachates to poison aqueous environments. In particular, large pH changes can cause undersaturation of CaCO3 polymorphs, damaging populations of calcifying organisms. Deposition of volcanic ash can both fertilize and/or poison aqueous environments, causing significant changes to surface water chemistry and biogeochemical cycles.

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Published date: 1 August 2008

Identifiers

Local EPrints ID: 63936
URI: http://eprints.soton.ac.uk/id/eprint/63936
ISSN: 0016-7037
PURE UUID: ede295ff-9261-4f52-b672-41b6e986db43

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Date deposited: 19 Nov 2008
Last modified: 15 Mar 2024 11:45

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Contributors

Author: Morgan T. Jones
Author: Sigurður R. Gislason

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