Theses and Dissertations
Issuing Body
Mississippi State University
Advisor
Dash, Padmanava
Committee Member
Mercer, Andrew E.
Committee Member
Ambinakudige, Shrinidhi
Committee Member
Feng, Gary
Date of Degree
8-9-2019
Original embargo terms
Visible MSU Only 3 Years
Document Type
Dissertation - Open Access
Major
Earth and Atmospheric Sciences
Degree Name
Doctor of Philosophy
Degree Name
Doctor of Philosophy (Ph.D)
College
College of Arts and Sciences
College
College of Arts and Sciences
Department
Department of Geosciences
Department
Department of Geosciences
Abstract
Dissolved organic matter (DOM) is a major component of natural waters and provides essential nutrients for aquatic organisms. However, excess DOM in the water results in water quality issues and affects the aquatic life negatively. The present research evaluated the source, composition, reactivity, dynamics, and the spatial distribution of DOM in diverse water bodies using spectrofluorometric methods in tandem with multivariate statistics. The study was conducted in the inland and coastal water bodies of Mississippi, Louisiana, and Alabama over a period of three years (2016 to 2018). Surface water samples were collected from spatially separated waterbodies with diverse land use and land cover classes. In addition, reactivity of DOM was assessed by conducting a series of laboratory experiments at varying magnitudes of sunlight and bacterial activity. Spatial distribution and mobility of DOM, nutrients and trace elements with respect to land cover classes and hydrology was evaluated using watershed delineation and multivariate statistics. Results suggest that microbial humic-like or protein-like DOM compositions derived from microbial/anthropogenic sources were less reactive than the terrestrial humic-like compositions originated from forests and woody wetlands. Furthermore, the sunlight was the major factor causing the degradation of DOM in the water bodies, while temperature had a minor effect. Additionally, the results also suggest that livestock fields in the pastoral and rangelands release a high amount of microbial humic-like DOM along with nutrients such as phosphates and nitrates into the water bodies. Present research identified the presence of four types of DOM in the study areas and were terrestrial humic-like, microbial humic-like, soil-derived humic-like and protein-like compositions. Additionally, trace element availability and mobility of coastal areas is influenced by local hydrology and precipitation. Research also identified forested areas as the major source of DOM to the water bodies of Mississippi. In conclusion, present research found that watershed land use and land cover, hydrology, and climate control the dynamics of DOM, other nutrients, and trace element delivery to the water bodies, while combined effects of light and bacteria are more efficient in reprocessing DOM chemistry within the waterbody.
URI
https://hdl.handle.net/11668/14490
Recommended Citation
Manalilkada Sasidharan, Sankar, "Characterization of dissolved organic matter and determination of its biogeochemical significance in coastal and inland water bodies" (2019). Theses and Dissertations. 1010.
https://scholarsjunction.msstate.edu/td/1010