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Biogeochemical weathering of iron-si...

Buss, Heather L.

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Biogeochemical weathering of iron-silicate minerals.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Biogeochemical weathering of iron-silicate minerals./
Author:	Buss, Heather L.
Description:	203 p.
Notes:	Adviser: Susan L. Brantley.
Contained By:	Dissertation Abstracts International67-08B.
Subject:	Agriculture, Soil Science. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3231811
ISBN:	9780542842399

Biogeochemical weathering of iron-silicate minerals.
Buss, Heather L.

Biogeochemical weathering of iron-silicate minerals. - 203 p.

Adviser: Susan L. Brantley.

Thesis (Ph.D.)--The Pennsylvania State University, 2006.

In the Rio Icacos watershed of Puerto Rico, which has the fastest documented chemical weathering rate of granitic rock in the world, the quartz diorite bedrock weathers spheroidally, producing a 0.2-2 m thick interface of partially weathered rock layers called rindlets. Plagioclase dissolution and biotite oxidation are the first observable weathering reactions in this system although it remains unknown which of these reactions occurs first. Dissolution of plagioclase produces porosity and may retard dissolution of other silicate minerals within the rindlet zone. Biotite weathering occurs in two stages: by oxidation within the rindlet zone and by alteration to kaolinite within the saprolite. Within a 0.07 m zone at the rindlet-saprolite interface, we document the fastest rate of hornblende dissolution in the field ever reported: 6.0 x 10-13 mol m -2 s-1.

ISBN: 9780542842399Subjects--Topical Terms:

1017824
Agriculture, Soil Science.

Biogeochemical weathering of iron-silicate minerals.
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005 20110906
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020 $a 9780542842399
035 $a (UMI)AAI3231811
035 $a AAI3231811
040 $a UMI $c UMI
100 1 $a Buss, Heather L. $3 1288237
245 1 0 $a Biogeochemical weathering of iron-silicate minerals.
300 $a 203 p.
500 $a Adviser: Susan L. Brantley.
500 $a Source: Dissertation Abstracts International, Volume: 67-08, Section: B, page: 4302.
502 $a Thesis (Ph.D.)--The Pennsylvania State University, 2006.
520 $a In the Rio Icacos watershed of Puerto Rico, which has the fastest documented chemical weathering rate of granitic rock in the world, the quartz diorite bedrock weathers spheroidally, producing a 0.2-2 m thick interface of partially weathered rock layers called rindlets. Plagioclase dissolution and biotite oxidation are the first observable weathering reactions in this system although it remains unknown which of these reactions occurs first. Dissolution of plagioclase produces porosity and may retard dissolution of other silicate minerals within the rindlet zone. Biotite weathering occurs in two stages: by oxidation within the rindlet zone and by alteration to kaolinite within the saprolite. Within a 0.07 m zone at the rindlet-saprolite interface, we document the fastest rate of hornblende dissolution in the field ever reported: 6.0 x 10-13 mol m -2 s-1.
520 $a The release of Fe(II) during hornblende dissolution supports the growth of iron-oxidizing bacteria at depth in the Rio Icacos saprolite. Fixation of CO2 by these bacteria supports growth of heterotrophic bacteria. A conceptual model is presented to quantify the effect of Fe(II) release during bedrock weathering on the microbial population at depth in the saprolite. Moreover, by consuming Fe(II) and O2, iron-oxidizing bacteria may affect spheroidal fracturing, which is likely driven by diffusion of O 2 into the bedrock and oxidation of Fe-silicate minerals.
520 $a Microorganisms also affect the mechanisms and rates of mineral weathering via the production of organic moieties that interact with mineral surfaces. Spectroscopic and microscopic techniques were utilized to investigate the surfaces of Fe-silicate glass surfaces after incubation with siderophores, extracellular polysaccharides (EPS), and/or of bacteria. Siderophores enhanced release of Fe, Al, and Si. Release of these elements was greatest in the presence of both EPS and siderophores, but negligible in the presence of EPS alone. Siderophore-exposed surfaces contained widespread, small etch pits and greater surface roughness than bacteria-exposed surfaces, which contained fewer, localized, larger etch pits. This is the first documented case in which mineral surface pitting by siderophores has been observed. Small acidic molecules released from the EPS may have shuttled Fe from the surfaces to the siderophores, enhancing general dissolution.
590 $a School code: 0176.
650 4 $a Agriculture, Soil Science. $3 1017824
650 4 $a Biogeochemistry. $3 545717
650 4 $a Geochemistry. $3 539092
690 $a 0425
690 $a 0481
690 $a 0996
710 2 0 $a The Pennsylvania State University. $3 699896
773 0 $t Dissertation Abstracts International $g 67-08B.
790 $a 0176
790 1 0 $a Brantley, Susan L., $e advisor
791 $a Ph.D.
792 $a 2006
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3231811