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9780542049248
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(UMI)AAI3168942
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AAI3168942
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UMI
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UMI
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Liang, Yuhong.
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Oxygen isotope studies of biogeochemical cycling of phosphorus
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[electronic resource]
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2005
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1 online resource (238 p.)
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Source: Dissertation Abstracts International, Volume: 66-03, Section: B, page: 1350.
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Director: Ruth E. Blake.
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Thesis (Ph.D.)--Yale University, 2005.
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Access is restricted by licensing agreement.
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Phosphorus (P) is essential for function and growth of all living organisms and limits primary productivity in some ocean regions today. Thus, it is important to understand the processes of P utilization in aquatic systems. P occurs in nature primarily in one oxidation state (+5) and in one form, orthophosphate (PO4). Although P has only one stable isotope (31P), during most biogeochemical cycling reactions P is bonded to oxygen (O), an element with three stable isotopes. Thus isotopic ratios of oxygen bonded to P provide an opportunity for stable isotope studies of reactions of P in nature. The overall goal of the studies in this thesis is to characterize the O isotope effects of the reactions that take place during biogeochemical cycling of P, and to apply these O isotopic signatures to trace the sources and the reaction pathways of P in natural environments.
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Distinctive and distinguishable O isotopic signatures are produced by different P cycling pathways. In experiments mimicking natural apatite formation, only a small fractionation (∼1‰) was observed between solid and aqueous Pi phases. Degradation of organic matter by UV photooxidation retains unaltered delta18O values of PO4 derived from phosphomonoesters; and microbial turnover of Pi---uptake and subsequent release by cells---will drive Pi toward equilibrium with ambient water (Blake et al., 2001). Pi regenerated from phosphomonoesters incorporates one O atom from ambient water, whereas Pi derived from phosphodiesters incorporates two. Incorporation of water O causes Pi regenerated from enzymatic degradation of Porg to shift away from equilibrium delta18O values.
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Pidelta18O was applied to study P cycling in organic-rich sediments with high microbial activities at the Peru Margin. The measured Pidelta18O values together with interstitial water chemistry show that in addition to a strong microbial turnover signature, two different processes (enzymatic Porg degradation and redox controlled Pi absorption/desorption) affect P cycling, and that microbial activity was the primary force behind post-deposition P redistribution. This successful application of Pidelta 18O values to tracing P cycling processes in natural environments strongly supports the use of Pidelta18O as a novel tool for studying reaction pathways of P in aquatic systems.
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Access is available to the Yale community
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Biogeochemistry.
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Geochemistry.
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Yale University.
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Dissertation Abstracts International
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66-03B.
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Blake, Ruth E.,
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advisor
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Ph.D.
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2005
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Online resource
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Online thesis
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https://yale.idm.oclc.org/login?URL=http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3168942
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Yale Internet Resource
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Yale Internet Resource >> None|DELIM|10145838
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online resource
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2011-07-12T20:12:06.000Z
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http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3168942