Identifier

etd-05312017-151916

Semester of Graduation

Summer 2017

Degree

Master of Science (MS)

Department

Plant, Environmental Management and Soil Sciences

Document Type

Thesis

Abstract

Sulfur is one of the most abundant elements in the environment, which plays a vital role in the growth and functioning of plants and microorganisms. It is found in an extended variety of species in gases, liquid, and solid forms and present in various nature systems. Wetlands are one of the largest global sinks/sources of sulfur. Being existing in a variety of oxidation states, sulfur contributes to biogeochemical cycles of coastal wetlands through involving in humification processes as well as influence on metal sulfide formation and consequently, methanogenesis and greenhouse gas emission. In this study, we have evaluated sulfur chemistry in surface and vertical profiles of coastal wetlands along salinity gradients and in two contrasting basins along the Louisiana coast. For this purpose, we chose Barataria baisn, experiencing land loss, and Atchafalaya basin, undergoing delta growing and land building process. Sulfur chemistry in soil composite profiles (up to 50 cm depth) and vibracores (up to 380 cm depth) were collected from wetland ecosystems of Barataria and Atchafalaya basin in southern Louisiana. The collected samples were analyzed using sulfur K-edge x-ray absorption near-edge structure (XANES) spectroscopy. Results suggested that salinity had a significant contribution to the speciation of sulfur oxidation states on these soils. Soils experiencing high salinity levels exhibited an increased proportion of sulfur containing compounds and higher oxidation states of sulfur in these wetland ecosystems. Conversely, a greater proportion of reduced sulfur species and organic compounds was observed in coastal areas experiencing lower salinity levels and in lower depths of the vibracore profiles, which are geochemically more stable. Highly oxidized sulfur compounds decreased as pyrite became the dominant compound along the soil profiles. The presence of organic disulfides inversely affected pyrite formation. Overall, the results showed substantial alteration in reduced organic and inorganic sulfur within and between the two contrasting basin soils.

Date

2016

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Wang, Jim

DOI

10.31390/gradschool_theses.4549

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