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Vitamin B12 distribution patterns in marine sediments revealed by a new ELISA method

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dc.contributor.advisor Zhu, Qingzhi en_US
dc.contributor.author Liu, Meichen en_US
dc.contributor.other Department of Marine and Atmospheric Science. en_US
dc.date.accessioned 2017-09-20T16:49:37Z
dc.date.available 2017-09-20T16:49:37Z
dc.date.issued 2013-12-01
dc.identifier.uri http://hdl.handle.net/11401/76195 en_US
dc.description 71 pg. en_US
dc.description.abstract Vitamin B<sub>12</sub> is an organic micronutrient in the ocean, and it is required for the growth of majority of phytoplankton. Because of the ultra-low concentrations of vitamin B<sub>12</sub> in the ocean and the lack of suitable analytical methods, the distribution, transport and biogeochemical cycling of vitamin B<sub>12</sub> in marine ecosystem have not been essentially documented. In this thesis, vitamin B<sub>12</sub> distribution and reaction patterns in water column and marine sediments were preliminary studied by using newly developed immunoassay methods. Two new sensitive and specific enzyme-linked immunosorbent assay (ELISA) methods have been developed and compared in Chapter two, based on indirect competitive immunoassay format, to measure the concentration of vitamin B<sub>12</sub> in coastal seawater and sediment porewater. Rabbit anti-vitamin B<sub>12</sub> polyclonal antibody was used to specific recognize vitamin B<sub>12</sub> from samples, horseradish peroxidase (HRP) was used as a labeling enzyme and tetramethylbenzidine (TMB) was as enzyme substrate. All the immunoassay conditions were optimized. Under the optimal conditions, the absorbance signal was inversely proportional to the concentration of vitamin B<sub>12</sub> in samples. The dynamic range for B<sub>12</sub> was 0.1 - 100 ng/ml with a detection limit of 0.05 ng/ml (3&sigma). Coupled with C-18 column solid-phase extraction - preconcentration, the ELISA methods were readily applicable to measure B<sub>12</sub> in marine samples. Vitamin B<sub>12</sub> distribution patterns in Long Island Sound water column were studied in Chapter three. Results show that vitamin B<sub>12</sub> has a higher concentration in sediment porewater than in overlying seawater, and the B<sub>12</sub> concentration gradually increases with depth in water column because the phytoplankton consumption and benthic sources could influence the vertical patterns of B<sub>12</sub>. The distributions of B<sub>12</sub> in seawater also show a seasonal variation. Vitamin B<sub>12</sub> distributions in marine sediments were also revealed by ELISA measurement, a vitamin B<sub>12</sub> concentration maximum zone was observed for the first time at the depth of ~2 cm in the sediment. The concentration of B<sub>12</sub> at sediment surface is close to that in the bottom water, however it increases sharply just below the water-sediment interface and reaches maximum at the oxic-anoxic boundary. Beneath the maximum, B<sub>12</sub> concentration significantly decreases with depth, and reaches almost constant below 4 cm in sediment, suggesting that bacteria at or near the oxic-anoxic boundary may be involved in the generation of vitamin B<sub>12</sub>. The new B<sub>12</sub> profiles provide insight into the source, cycling and transport of vitamin B<sub>12</sub>. Adsorption-desorption behaviors of vitamin B<sub>12</sub> on sediment particles under various conditions were studied in order to elucidate the B<sub>12</sub> profiles and transport in sediments. It was found that in natural conditions over 99% vitamin B<sub>12</sub> was adsorbed on particles in marine sediments, and the adsorption was likely irreversible. The physical and chemical adsorption of B<sub>12</sub> on particles may dominate its distribution and transport in sediment and across sediment-water interface. en_US
dc.description.sponsorship This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree. en_US
dc.format Monograph en_US
dc.format.medium Electronic Resource en_US
dc.language.iso en_US en_US
dc.publisher The Graduate School, Stony Brook University: Stony Brook, NY. en_US
dc.subject.lcsh Chemical oceanography en_US
dc.subject.other ELISA, marine sediment, vitamin B12 en_US
dc.title Vitamin B12 distribution patterns in marine sediments revealed by a new ELISA method en_US
dc.type Thesis en_US
dc.mimetype Application/PDF en_US
dc.contributor.committeemember Aller, Robert en_US
dc.contributor.committeemember Aller, Josephine. en_US


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