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Sorption Temperature and and the Stability of Iron-Bound Soil Organic Matter

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dc.contributor.advisorBoris Lau
dc.contributor.advisorWilliam Hockaday
dc.contributor.authorNguyen, Michael L
dc.contributor.departmentUniversity of Massachusetts Amherst
dc.date2024-03-27T17:04:39.000
dc.date.accessioned2024-04-26T15:30:48Z
dc.date.available2024-04-26T15:30:48Z
dc.date.submittedMay
dc.date.submitted2019
dc.description.abstractThe preservation of soil organic matter (SOM) is an important control on the global cycling of carbon. Long-term preservation of SOM has important implications on soil fertility and climate regulation. Minerals, such as iron oxides, can react with SOM and serve as a preservation mechanism for SOM. Globally, iron oxide-SOM interactions form a “rusty carbon sink” which protects up to 22% of organic carbon in marine sediments. Climate changes, such as warming, may alter the size or efficacy of the “rusty carbon sink.” The effects of temperature, SOM composition, and mineral particle size on the formation and stability of iron oxide-SOM associations were investigated through batch sorption experiments, incubation experiments, and thermal analyses. The sorption extent of humic acid (HA) to microphase hematite was greater than that of fulvic acid (FA). The sorption extent for both HA and FA was found to be independent of temperature. The incubation and thermal analysis of microphase hematite-bound SOM suggested that HA is more biologically stable and less exergonic upon decomposition than FA, but there were no relationships with stability and sorption temperature. When normalized to specific surface area, the sorption extent of HA to nanophase hematite had a greater sorption extent than microphase hematite, but the sorption extent of nanophase hematite was also found to be temperature-independent. These results suggest that the size and efficacy of the “rusty carbon sink” may remain unchanged with warming climates. Furthermore, these results highlight (1) the importance of indirect temperature effects such as increased weathering and precipitation reactions which can alter the particle size distribution of soils and sediments and (2) SOM composition over direct sorption temperature in understanding future SOM dynamics.
dc.description.degreeDoctor of Philosophy (PhD)
dc.description.departmentGeosciences
dc.identifier.doihttps://doi.org/10.7275/14168038
dc.identifier.orcidhttps://orcid.org/0000-0002-7413-5499
dc.identifier.urihttps://hdl.handle.net/20.500.14394/17829
dc.relation.urlhttps://scholarworks.umass.edu/cgi/viewcontent.cgi?article=2647&context=dissertations_2&unstamped=1
dc.source.statuspublished
dc.subjectMineral-organic associations
dc.subjectIron oxides
dc.subjectHumic substances
dc.subjectTemperature
dc.subjectSorption
dc.subjectStability
dc.subjectBiogeochemistry
dc.subjectGeochemistry
dc.subjectSoil Science
dc.titleSorption Temperature and and the Stability of Iron-Bound Soil Organic Matter
dc.typeopenaccess
dc.typearticle
dc.typedissertation
digcom.contributor.authorisAuthorOfPublication|email:nguyeml08@gmail.com|institution:University of Massachusetts Amherst|Nguyen, Michael L
digcom.identifierdissertations_2/1594
digcom.identifier.contextkey14168038
digcom.identifier.submissionpathdissertations_2/1594
dspace.entity.typePublication
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