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Biological residues define the ice nucleation properties of soil dust
JournalArticle (Originalarbeit in einer wissenschaftlichen Zeitschrift)
 
ID 784157
Author(s) Conen F, Morris C. E.; Leifeld J, Yakutin M. V.; Alewell, C.
Author(s) at UniBasel Conen, Franz
Alewell, Christine
Year 2011
Title Biological residues define the ice nucleation properties of soil dust
Journal Atmospheric Chemistry and Physics
Volume 11
Number 18
Pages / Article-Number 9643-9648
Abstract

Soil dust is a major driver of ice nucleation in clouds leading to precipitation. It consists largely of mineral particles with a small fraction of organic matter constituted mainly of remains of micro-organisms that participated in degrading plant debris before their own decay. Some micro-organisms have been shown to be much better ice nuclei than the most efficient soil mineral. Yet, current aerosol schemes in global climate models do not consider a difference between soil dust and mineral dust in terms of ice nucleation activity. Here, we show that particles from the clay and silt size fraction of four different soils naturally associated with 0.7 to 11.8 % organic carbon (w/w) can have up to four orders of magnitude more ice nucleation sites per unit mass active in the immersion freezing mode at −12 įC than montmorillonite, the nucleation properties of which are often used to represent those of mineral dusts in modelling studies. Most of this activity was lost after heat treatment. Removal of biological residues reduced ice nucleation activity to, or below that of montmorillonite. Desert soils, inherently low in organic content, are a large natural source of dust in the atmosphere. In contrast, agricultural land use is concentrated on fertile soils with much larger organic matter contents than found in deserts. It is currently estimated that the contribution of agricultural soils to the global dust burden is less than 20 %. Yet, these disturbed soils can contribute ice nuclei to the atmosphere of a very different and much more potent kind than mineral dusts.

Publisher European Geosciences Union
ISSN/ISBN 1680-7316 ; 1680-7324
edoc-URL http://edoc.unibas.ch/45963/
Full Text on edoc Available
Digital Object Identifier DOI 10.5194/acp-11-9643-2011
ISI-Number WOS:000295368700013
Document type (ISI) Article
 
   

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