Effect of Atmospheric Processes on the Bioavailability of Phosphorus Supplied by Dust to the Surface Ocean. How Globally Important is this Process?
Presented by Professor Mike Krom
School of Earth and Environment, University of Leeds, UK
Although there is no gaseous form of P, atmospheric supply of P can still be an important source of ‘new’ nutrients especially to the offshore ocean. However most of particulate P (Desert dust) is in the form of apatite which is not immediately bioavailable and tends to fall through the photic zone without being taken up by phytoplankton. In this study we used lab experiments to mimic atmospheric acidic processes to determine their importance in converting apatite to labile P. Our results show that for low H+ ion concentrations in wet aerosols, there is no dissolution of apatite and the original labile P is supplied to the ocean. However over an important range of H+ content, apatite is converted into labile phosphate and this reaction occurs even in the presence of CaCO3. The CaCO3 content controls the pH in the wet aerosol. At high concentrations of H+ all the apatite is dissolved. We show that the amount of P converted is higher in systems where the apatite and calcite are on separate particles than when the minerals are present on the same particles. The dissolution data was then applied using a GCM model together with a soil map of P mineralogy to determine the magnitude and relative importance of these processes in supplying this essential nutrient to the global ocean.
Everyone Welcome. Coffee Provided.
Unfortunately, the second seminar previously announced to follow Mike Krom has been CANCELLED
**11AM seminar CANCELLED: The Enigma of Organic Phosphorus Preserved in Marine Sediments**