Type
Text
Type
Thesis
Advisor
Zhu, Qingzhi | Aller, Robert | Aller, Josephine.
Date
2013-12-01
Keywords
ELISA, marine sediment, vitamin B12 | Chemical oceanography
Department
Department of Marine and Atmospheric Science.
Language
en_US
Source
This work is sponsored by the Stony Brook University Graduate School in compliance with the requirements for completion of degree.
Identifier
http://hdl.handle.net/11401/76096
Publisher
The Graduate School, Stony Brook University: Stony Brook, NY.
Format
application/pdf
Abstract
Vitamin B12 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 B12 in the ocean and the lack of suitable analytical methods, the distribution, transport and biogeochemical cycling of vitamin B12 in marine ecosystem have not been essentially documented. In this thesis, vitamin B12 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 B12 in coastal seawater and sediment porewater. Rabbit anti-vitamin B12 polyclonal antibody was used to specific recognize vitamin B12 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 B12 in samples. The dynamic range for B12 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 B12 in marine samples. Vitamin B12 distribution patterns in Long Island Sound water column were studied in Chapter three. Results show that vitamin B12 has a higher concentration in sediment porewater than in overlying seawater, and the B12 concentration gradually increases with depth in water column because the phytoplankton consumption and benthic sources could influence the vertical patterns of B12. The distributions of B12 in seawater also show a seasonal variation. Vitamin B12 distributions in marine sediments were also revealed by ELISA measurement, a vitamin B12 concentration maximum zone was observed for the first time at the depth of ~2 cm in the sediment. The concentration of B12 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, B12 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 B12. The new B12 profiles provide insight into the source, cycling and transport of vitamin B12. Adsorption-desorption behaviors of vitamin B12 on sediment particles under various conditions were studied in order to elucidate the B12 profiles and transport in sediments. It was found that in natural conditions over 99% vitamin B12 was adsorbed on particles in marine sediments, and the adsorption was likely irreversible. The physical and chemical adsorption of B12 on particles may dominate its distribution and transport in sediment and across sediment-water interface. | 71 pages
Recommended Citation
Liu, Meichen, "Vitamin B12 distribution patterns in marine sediments revealed by a new ELISA method" (2013). Stony Brook Theses and Dissertations Collection, 2006-2020 (closed to submissions). 2046.
https://commons.library.stonybrook.edu/stony-brook-theses-and-dissertations-collection/2046