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SUMMARY:Ocean iron-fertilisation by volcanic ash - Baerbel Langmann\, Inst
 itute of Geophysics\, University of Hamburg
DTSTART:20090520T131500Z
DTEND:20090520T141500Z
UID:TALK18274@talks.cam.ac.uk
CONTACT:Dr Glenn Carver
DESCRIPTION:Marine primary productivity (MPP) can be limited by the availa
 bility of macro-nutrients like nitrate and phosphate. In so-called ‘High
 -Nutrient-Low-Chlorophyll’ (HNLC) areas\, macro-nutrient concentrations 
 are high\, but iron is the key biologically limiting micro-nutrient for pr
 imary production. Three major sources for iron supply into the ocean have 
 been considered so far: upwelling of deep ocean water\, advection from the
  continental margins and atmospheric deposition with aeolian dust depositi
 on commonly assumed to dominate external iron supply to the open ocean. Ir
 on supply to HNLC regions can affect climate relevant ocean-atmosphere exc
 hanges of chemical trace species\, e.g. organic carbon aerosols\, DMS and 
 CO2. Marine aerosols can act as efficient cloud condensation nuclei and si
 gnificantly influence cloud properties and thus the Earth’s radiative bu
 dget via the indirect aerosol effects whereas a drawdown of atmospheric CO
 2 due to ocean fertilisation can have important implications for the globa
 l CO2 budget. Recent laboratory experiments suggest that material from vol
 canic eruptions such as ash may also affect the MPP through rapid iron-rel
 ease on contact with seawater. Direct evidence\, however\, that volcanic a
 ctivity can cause natural iron-fertilisation and MPP increase has been lac
 king so far. Here first evidence for a large-scale phytoplankton bloom res
 ulting from volcanic ash fall is presented. 
LOCATION:Pfizer Lecture Theatre\, Department of Chemistry
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