Distribution of Vitamin B12 in waters of the central Great Barrier Reef

A highly sensitive and selective method was used to estimate concentrations of cyanocobalamin (Vitamin B12) in sea water along a transect of reefs across the central portion of the Great Barrier Reef. Water samples were collected from a depth of 0.5 m along each transect (moving from reef front to reef back) at Pandora, Rib and Myrmidon Reefs. Samples were also collected from Palm Passage at a depth of 10m. Analyses were based on clinical techniques of radioimmunoassay, combining the RIA method with preconcentration of Vitamin B12 by displacement liquid chromatography on C18 SEP-PAK columns. Analyses of the column eluate by radioassay proved sensitive to B12 at femtomolar concentrations (50-2400 pg B12/L seawater). The concentrations calculated from the radioassay translated directly into units of pg B12/L and ng folate/L seawater as a consequence of the concentration procedure. Concentrations above calibration range (2400 pg B 12; 24.0 ng folate) were determined by extrapolation. To determine changes in Vitamin B12 concentrations of sea water along a transect of reefs across the central portion of the Great Barrier Reef.

本研究采用高灵敏、高选择性的方法，对大堡礁（Great Barrier Reef）中部区域沿礁体断面采集的海水中氰钴胺（cyanocobalamin，维生素B12）的浓度进行定量估算。在潘多拉礁（Pandora Reef）、里布礁（Rib Reef）与迈尔米登礁（Myrmidon Reef）的每个断面中，均从0.5米水深处采集水样，采样方向为从礁前至礁后。此外还在棕榈航道（Palm Passage）10米水深处采集了水样。本研究的分析方法基于临床放射免疫分析法（radioimmunoassay，简称RIA），将RIA检测与C18 SEP-PAK柱置换液相色谱预富集维生素B12的步骤相结合。通过放射测定法对柱洗脱液进行分析，结果显示该方法对飞摩尔浓度级别的维生素B12具有优异灵敏度，检测范围为50~2400 pg 维生素B12/升海水。经该富集流程后，通过放射测定法计算得到的浓度可直接换算为pg维生素B12/升海水与纳克叶酸/升海水的单位。超出校准范围（2400 pg 维生素B12；24.0 ng 叶酸）的浓度值通过外推法得到。本研究旨在探究大堡礁中部区域沿礁体断面的海水维生素B12浓度变化特征。