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Lead and selenium distributions and ...

Templeton, Alexis Sladen.

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Lead and selenium distributions and speciation at biofilm/metal oxide interfaces.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Lead and selenium distributions and speciation at biofilm/metal oxide interfaces./
作者:	Templeton, Alexis Sladen.
面頁冊數:	212 p.
附註:	Adviser: Gordon E. Brown, Jr.
Contained By:	Dissertation Abstracts International63-01B.
標題:	Biogeochemistry. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3040072
ISBN:	0493533974

Lead and selenium distributions and speciation at biofilm/metal oxide interfaces.
Templeton, Alexis Sladen.

Lead and selenium distributions and speciation at biofilm/metal oxide interfaces. - 212 p.

Adviser: Gordon E. Brown, Jr.

Thesis (Ph.D.)--Stanford University, 2002.

The geochemical cycling of trace elements in soil and aquatic systems is strongly influenced by sorption and precipitation reactions that occur at metal (hydr)oxide surfaces. However, the electrical and chemical properties of the mineral-water interface can be dramatically modified by the formation of highly hydrated, highly reactive microbial biofilms. We have developed synchrotron-based experimental approaches to quantitatively probe the distribution and speciation of Pb and Se sequestered within complex <italic> Burkholderia cepacia</italic> biofilms coating Al- and Fe-oxides. X-ray absorption spectroscopy was used to determine the speciation of the metal(loid) ions (e.g., mode of metal binding, changes in redox state) associated with the biofilms <italic>vs.</italic> the metal-oxide surfaces. XSW measurements were used to profile the vertical distribution of metal(loid) ions within microbial biofilms formed on single-crystal surfaces, and X-ray microscopy was used to map the lateral heterogeneities in metal(loid) distribution within the biofilms. The spectroscopic data were coupled to images of the biofilms obtained using epifluorescent, transmission electron (TEM) and scanning electron (SEM) microscopy.

ISBN: 0493533974Subjects--Topical Terms:

545717
Biogeochemistry.

Lead and selenium distributions and speciation at biofilm/metal oxide interfaces.
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245 1 0 $a Lead and selenium distributions and speciation at biofilm/metal oxide interfaces.
300 $a 212 p.
500 $a Adviser: Gordon E. Brown, Jr.
500 $a Source: Dissertation Abstracts International, Volume: 63-01, Section: B, page: 0134.
502 $a Thesis (Ph.D.)--Stanford University, 2002.
520 $a The geochemical cycling of trace elements in soil and aquatic systems is strongly influenced by sorption and precipitation reactions that occur at metal (hydr)oxide surfaces. However, the electrical and chemical properties of the mineral-water interface can be dramatically modified by the formation of highly hydrated, highly reactive microbial biofilms. We have developed synchrotron-based experimental approaches to quantitatively probe the distribution and speciation of Pb and Se sequestered within complex <italic> Burkholderia cepacia</italic> biofilms coating Al- and Fe-oxides. X-ray absorption spectroscopy was used to determine the speciation of the metal(loid) ions (e.g., mode of metal binding, changes in redox state) associated with the biofilms <italic>vs.</italic> the metal-oxide surfaces. XSW measurements were used to profile the vertical distribution of metal(loid) ions within microbial biofilms formed on single-crystal surfaces, and X-ray microscopy was used to map the lateral heterogeneities in metal(loid) distribution within the biofilms. The spectroscopic data were coupled to images of the biofilms obtained using epifluorescent, transmission electron (TEM) and scanning electron (SEM) microscopy.
520 $a X-ray standing wave data show that Pb and Se ions rapidly penetrate the <italic> Burkholderia cepacia</italic> biofilms and preferentially bind to highly reactive sites on the Al- and Fe-oxide surfaces. Once these reactive sites are saturated, sorption to surface functional groups present within the biofilms becomes quantitatively important. Therefore, <italic>B. cepacia</italic> biofilms do not passivate the intrinsic reactivity of the metal-oxide surfaces. Moreover, structural fitting of Pb L<sub>III</sub>-EXAFS spectra collected for Pb(II) sorbed to <italic>B. cepacia</italic>/goethite composites, coupled to macroscopic uptake data, show that the presence of <italic>B. cepacia</italic> enhances Pb(II) uptake at goethite surfaces, primarily through the stabilization of bidentate, binuclear Pb(II) complexes.
520 $a The metabolic activity of <italic>B. cepacia</italic> has a dramatic effect on the speciation and bioavailability of Pb and Se. At micromolar Pb<super> 2+</super> concentrations, <italic>B. cepacia</italic> induces the biomineralization of pyromorphite, a sparingly soluble Pb-phosphate phase, adjacent to the outer-membrane. For Se, <italic>B. cepacia</italic> catalyzes the rapid reduction of Se(IV) and partial reduction of Se(VI) to elemental Se(0). The Se species differentially segregate at the biofilm/metal-oxide interface, where Se(VI) and Se(0) are associated with the biofilms whereas Se(IV) is preferentially bound to the underlying mineral surface.
590 $a School code: 0212.
650 4 $a Biogeochemistry. $3 545717
650 4 $a Geochemistry. $3 539092
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