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dc.contributor.authorRogers, Daniel R.  Concept link
dc.coverage.spatial41°34’49”N, 70°31’27”W
dc.coverage.spatialWaquoit, MA
dc.date.accessioned2010-07-21T20:02:46Z
dc.date.available2010-07-21T20:02:46Z
dc.date.issued2010-06
dc.identifier.urihttps://hdl.handle.net/1912/3817
dc.descriptionSubmitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2010en_US
dc.description.abstractExcess nitrogen input is deleterious to coastal waters, resulting in deterioration of the water quality, increases in harmful algal blooms and disease in commercial fish stocks. A significant portion of this nitrogen enters coastal waters through groundwater systems. Here we use isotopic and molecular biological methods to identify the populations of nitrifiers and denitrifiers, where they occur, and what levels of activity are present through the upper four meters of a coastal groundwater system. This work shows two different populations of putative ammonia-oxidizing archaea (AOA) based on the ammonia monooxygenase gene (amoA), one shallow population most closely related to open ocean water column-like sequences and a deeper population that is more closely related to estuarine-like AOA. Interestingly, while the surface population has a potential nitrification rates (456 pmol g-1 sediment day-1) similar to marine sediments, the deeper population does not show detectable evidence of nitrification. Between these two archaeal populations resides an active population of ammonia-oxidizing bacteria with similar nitrification rates as the surface AOA population. The upper meter of the aquifer is also an active area of denitrification as evidenced by the coincident drop in nitrate concentration and increase in both δ15N (up to + 20.1‰) and δ18O (up to + 11.7‰), characteristic of groundwater affected by denitrification. 16S rRNA gene surveys of the organisms present in the upper meter also are similar to soil/sediment type environments including many potential denitrifiers. However, nitrite reductase, nirS and nirK, genes were also recovered from the sediments with nirK dominating in the surface sediments. This contrasts with the deep salt wedge, where the microbial community 16S rRNA genes appear more closely related to marine or reducing sediment/wastewater type organisms, and nirS genes become the dominant denitrification gene.en_US
dc.description.sponsorshipFunding for the following work was generously provided by the National Science Foundation (KLC, OCE-0526277 and MAC, OCE-0524994), the Woods Hole Oceanographic Institution’s Coastal Ocean Institute (KLC and DRR, 32031013), Ocean Venture Fund (DRR), Coastal Ocean Institute fellowship (DRR), and the Academic Programs Office of the MIT/WHOI Joint Program in Oceanography/Applied Ocean Science and Engineering.en_US
dc.format.mimetypeapplication/pdf
dc.language.isoen_USen_US
dc.publisherMassachusetts Institute of Technology and Woods Hole Oceanographic Institutionen_US
dc.relation.ispartofseriesWHOI Thesesen_US
dc.subjectGroundwateren_US
dc.subjectWateren_US
dc.subjectNitrogen contenten_US
dc.titleGeomicrobiology of nitrogen in a coastal aquifer : isotopic and molecular methods to examine nitrification and denitrification in groundwateren_US
dc.typeThesisen_US
dc.identifier.doi10.1575/1912/3817


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