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Anthropogenic and environmental drivers of the input and uptake of dissolved organic matter in temperate streams

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dc.contributorDimova, Natasha
dc.contributorZhang, Yong
dc.contributorWard, Amelia
dc.contributorAtkinson, Carla
dc.contributor.advisorLu, Yuehan
dc.contributor.authorShang, Peng
dc.contributor.otherUniversity of Alabama Tuscaloosa
dc.date.accessioned2020-01-16T15:03:47Z
dc.date.available2020-01-16T15:03:47Z
dc.date.issued2019
dc.descriptionElectronic Thesis or Dissertationen_US
dc.description.abstractDissolved organic matter (DOM) is a complex mixture of organic compounds and plays an essential role in regulating substrate and energy flows in aquatic ecosystems. However, environmental factors and biogeochemical mechanisms mediating the supply and uptake of DOM in streams are not well understood. The overarching goal of this dissertation is to assess the effects of the anthropogenic and natural drivers on the amount, source, composition, and fate of DOM in streams. The objective of Chapter II is to understand the effects of agricultural activities on DOM in a regional group of streams in Southeastern Alabama. The main finding is that agricultural land use increases DOC concentration and the proportions of terrestrial and microbial humic DOM compounds in streams, which suggests that agricultural activities accelerate the mobilization of organic matter from topsoils via enhancing oxidation, erosional transport, and shifting soil-to-stream flow paths. The objective of Chapter III is to identify the environmental drivers controlling the supply of terrestrial DOM in a Coastal Plain stream draining a forest-dominated watershed. The main finding is that discharge can be used to predict DOM supply across timescales, but other environmental drivers could be important at a given timescale. Specifically, the event-scale DOM supply is influenced by antecedent hydrological conditions and the duration of storms. At the diurnal scale, DOM variation is driven by physical dilution and concentration due to evapotranspiration. At the seasonal scale, DOM variation is mediated by organic matter availability from litterfall and discharge. The objective of Chapter IV is to determine the rates of natural DOM removal and identify the associated biogeochemical mechanisms in a second-order stream draining a forest-dominated watershed. The results provide the first record simultaneously measuring the uptake characters of humic-like and protein-like DOM, which demonstrates that humic-like DOM has a shorter uptake length and higher uptake velocity than protein-like DOM due to the preferential adsorption of humic-like compounds to benthic sediments. This dissertation improves our understandings of the supply and demand of DOM in subtropical streams in response to human land use and hydrological events, contributing to a greater understanding of the factors mediating the aquatic ecosystem response.en_US
dc.format.extent200 p.
dc.format.mediumelectronic
dc.format.mimetypeapplication/pdf
dc.identifier.otheru0015_0000001_0003426
dc.identifier.otherShang_alatus_0004D_13858
dc.identifier.urihttp://ir.ua.edu/handle/123456789/6483
dc.languageEnglish
dc.language.isoen_US
dc.publisherUniversity of Alabama Libraries
dc.relation.hasversionborn digital
dc.relation.ispartofThe University of Alabama Electronic Theses and Dissertations
dc.relation.ispartofThe University of Alabama Libraries Digital Collections
dc.rightsAll rights reserved by the author unless otherwise indicated.en_US
dc.subjectGeochemistry
dc.subjectEnvironmental geology
dc.titleAnthropogenic and environmental drivers of the input and uptake of dissolved organic matter in temperate streamsen_US
dc.typethesis
dc.typetext
etdms.degree.departmentUniversity of Alabama. Department of Geological Sciences
etdms.degree.disciplineGeology
etdms.degree.grantorThe University of Alabama
etdms.degree.leveldoctoral
etdms.degree.namePh.D.

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