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SUMMARY:Chasing waterfalls: constraining the global sulfur isotopic budget
  in rivers - Andrea Burke\, St Andrews
DTSTART:20141104T160000Z
DTEND:20141104T170000Z
UID:TALK54319@talks.cam.ac.uk
CONTACT:John Maclennan
DESCRIPTION:The sulfur cycle has an important influence on global climate\
 , for instance through weathering and aerosols\, and is intricately linked
  to both the carbon and oxygen cycles. However\, many aspects of the moder
 n sulfur budget are not well understood. We present new d34S measurements 
 on aqueous sulfate from more than 50 rivers from different geographical an
 d climatic regions. These data were measured by a new MC-ICP-MS method tha
 t requires only 10 nmol of sulfate [Paris et al.\, 2013]\, with typical is
 otopic uncertainties of only 0.1‰. Combined with previously published su
 lfur isotope data\, more than 50% of the world’s freshwater flux to the 
 ocean is involved in this estimate of the global riverine sulfur isotopic 
 budget.  Combined with major anion and cation data\, the sulfur isotope da
 ta allows us to tease apart the relative contributions of different proces
 ses to the modern sulfur budget\, including the oxidative weathering of py
 rites\, the weathering of sedimentary sulfates\, and anthropogenic influen
 ces. These data yield important insights into the modern sulfur cycle and 
 the weathering of sulfur bearing minerals\, and are first order terms in b
 alancing the modern sulfur isotopic budget. The large range of sulfur isot
 opic ratios in modern rivers has implications for our intepretation of the
  past changes in the sulfur isotopic composition of seawater. Secular chan
 ges in the lithologies exposed to weathering through time could play a maj
 or role in driving the variations in d34S in seawater over the Phanerozoic
 .\n\nParis\, G.\, A. L. Sessions\, A. V. Subhas\, and J. F. Adkins (2013)\
 , Chemical Geology\, Chemical Geology\, 345(C)\, 1–12\, doi:10.1016/j.ch
 emgeo.2013.02.022.\n\n\nCalmels\, D.\, J. Gaillardet\, A. Brenot\, and C. 
 France-Lanord (2007)\, Sustained sulfide oxidation by physical erosion pro
 cesses in the Mackenzie River basin: Climatic perspectives\, Geology\, 35(
 11)\, 1003\, doi:10.1130/G24132A.1.\n\nHalevy\, I.\, S. E. Peters\, and W.
  W. Fischer (2012)\, Sulfate Burial Constraints on the Phanerozoic Sulfur 
 Cycle\, Science\, 337(6092)\, 331–334\, doi:10.1126/science.1220224.\n\n
 Turchyn\, A.V.\, E. T. Tipper\, A. Galy\, J.-K. Lo\, M. J. Bickle\, Isotop
 e evidence for secondary sulfide precipitation along the Marsyandi River\,
  Nepal\, Himalayas\, Earth and Planetary Science Letters\, Volume 374\, 15
  July 2013\, Pages 36-46\, ISSN 0012-821X\, http://dx.doi.org/10.1016/j.ep
 sl.2013.04.033.
LOCATION:Harker 1 seminar room\, Department of Earth Sciences
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