000000596 001__ 596
000000596 005__ 20260107074959.0
000000596 0247_ $$2DOI$$a10.6083/M4V98623
000000596 037__ $$aETD
000000596 245__ $$aBiogeochemical and molecular biological characterization of nitrogen cycle processes in the Columbia River and estuary
000000596 260__ $$bOregon Health and Science University
000000596 269__ $$a2011
000000596 336__ $$aThesis
000000596 502__ $$bM.S.
000000596 502__ $$gEnvironmental Systems and Human Health
000000596 520__ $$aHuman activities now contribute over 50% of global reactive nitrogen (Nr) fixation, significantly increasing Nr flux to rivers and driving eutrophication and greenhouse gas emissions. This study examines nitrification within the Columbia River System (CRS), a major freshwater source to the North Pacific, using molecular characterization, chemical sensors, and stable isotope techniques. Results indicate ammonia-oxidizing archaea (AOA) play a key role in ammonia oxidation—the rate-limiting step of nitrification—particularly in salinity-influenced estuarine zones during upwelling and low-flow conditions. Findings highlight the spatial and temporal sensitivity of nitrification processes and their implications for Nr cycling and regional biogeochemistry.
000000596 540__ $$fCC BY
000000596 542__ $$fIn copyright - single owner
000000596 650__ $$aNitrification$$039195
000000596 650__ $$aQuaternary Ammonium Compounds$$014609
000000596 650__ $$aEstuaries$$040221
000000596 650__ $$aFiltration$$019046
000000596 650__ $$aEutrophication$$018755
000000596 650__ $$aNitrification$$039195
000000596 650__ $$aGreenhouse Gases$$012332
000000596 650__ $$aAmmonia$$014606
000000596 650__ $$aArchaea$$015036
000000596 651__ $$aUnited States$$041167
000000596 651__ $$aWashington$$041180
000000596 651__ $$aOregon$$041094
000000596 651__ $$aUnited States--Columbia River$$044429
000000596 6531_ $$ashields (geology)
000000596 6531_ $$ainner filter effect
000000596 6531_ $$aammonia-oxidizing archaea
000000596 691__ $$aSchool of Medicine$$041369
000000596 692__ $$aDepartment of Environmental and Biomolecular Systems$$041414
000000596 7001_ $$aMoeller, Florian$$uOregon Health and Science University$$041354
000000596 7201_ $$aNeedoba, Joseph$$uOregon Health and Science University$$041354$$7Personal$$eAdvisor
000000596 8564_ $$9c78b916e-b5ed-41d1-9134-06d23df9746f$$s1151264$$uhttps://digitalcollections.ohsu.edu/record/596/files/597_etd.pdf$$ePublic$$24bf1c35cf1af9a554652d272db38bb3d$$31
000000596 905__ $$a/rest/prod/fq/97/7t/83/fq977t83q
000000596 909CO $$ooai:digitalcollections.ohsu.edu:596$$pstudent-work
000000596 980__ $$aTheses and Dissertations