Controls on the sulfur cycle in estuarine sediments on the Central Texas coast /

Bibliographic Details
Main Author: Thomson, Heather
Other Authors: Morse, John W. (Thesis advisor)
Format: Thesis eBook
Language:English
Published: [College Station, Tex.] : [Texas A&M University], [2010]
Subjects:
Online Access:Link to OAK Trust copy

MARC

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100 1 |a Thomson, Heather. 
245 1 0 |a Controls on the sulfur cycle in estuarine sediments on the Central Texas coast /  |c by Heather Thomson. 
264 1 |a [College Station, Tex.] :  |b [Texas A&M University],  |c [2010] 
300 |a 1 online resource. 
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338 |a online resource  |b cr  |2 rdacarrier 
500 |a "Major Subject: Oceanography" 
500 |a Title from author supplied metadata (automated record created 2010-03-12 12:08:51). 
502 |b Master of Science  |c Texas A&M University  |d 2006  |o http://hdl.handle.net/1969.1/ETD-TAMU-1834 
504 |a Includes bibliographical references. 
516 |a Text (Thesis) 
520 3 |a The sedimentary sulfur cycle is one of the main components of estuarine biogeochemical systems. It is initiated by the oxidation of organic matter via sulfate reducing bacteria which produce hydrogen sulfide (H2S). The S(II) then reacts via both abiotic and biotic pathways to form sulfur with other oxidation states. The three most widely-studied 'operationally''defined components of the sedimentary sulfur system are total reduced (inorganic) sulfur (TRS), acid volatile sulfide (AVS), and dissolved (=filter-passing) sulfide. This study focused on several parameters that are widely held to be important in determining TRS in sediments and the relative proportions of TRS, AVS and dissolved S(II) forms. The formation of iron sulfide minerals requires metabolizable organic matter and SO4 2- to produce S(II) and 'reactive'-Fe as a source for the iron in iron sulfide minerals. One of these components is generally the limiting factor in TRS formation (e.g., Berner 1970). Nine different sites from three locations on the Central Texas coast were studied for a variety of parameters including organic matter, sulfate concentrations, sulfate reduction rate, solid 'reactive' and dissolved iron, and grain size, as well as TRS, AVS, and EH2S. At each site five sediment cores were taken to a depth of 20 cm whenever possible. The cores were sectioned in 2 cm intervals. The porewater was extracted and both solid and dissolved components were analyzed using a variety of methods, including carbon and sulfur coulometry, acid extraction, chromium extraction, and drying the sediment. The results of he analyses showed that the central Texas coast is a widely diverse system. Some sites were very sandy while others were fine-grained. This variety was especially true for the Nueces Bay and Baffin Bay sites. The East Matagorda Bay sites showed more homogeneity in almost all analysis. While the heterogeneity of locations along the Central Texas coast makes it difficult to make a definitive statement about the controls on TRS in this area, most sites are controlled by the low amounts of iron in the system, which limits the amount of iron sulfide that can form. Low reactive iron concentrations and high degrees of pyritization (DOPs) support this argument. Exceptions exist for low-salinity (sulfate-limited) or very fine-grained (organic matter limited) sites. 
500 |a Electronic resource. 
650 4 |a Major oceanography. 
653 |a sulfur cycle 
653 |a TRS 
653 |a AVS 
653 |a estuary 
700 1 |a Morse, John W.,  |e thesis advisor. 
856 4 0 |u http://hdl.handle.net/1969.1/ETD-TAMU-1834  |z Link to OAK Trust copy  |t 0 
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