The in situ solid-phase extraction of selected dissolved materials in the marine environment.

• Main Author: Slauenwhite, David Esson.
• Other Authors: Ph.D.
• Format: Text
• Language: English
• Published: Dalhousie University 2014
• Subjects: Physical Oceanography; Engineering; Marine and Ocean; Environmental Sciences; Canada; North Atlantic
• Online Access: http://hdl.handle.net/10222/55289

A number of methods have been devised to limit contamination in seawater sampling, with most relying on sophisticated sampling techniques. One of these methods is the use of a solid phase extractant along with an in situ pump sampler. This primary aim of this thesis is to examine this type of system, and to increase our understanding of some dissolved trace chemical species in general. The focus of this thesis is on: (1) the study of physical and chemical parameters of extractant columns for use with the in situ pump; (2) the study of Cu and Cd geochemistry during phytoplankton blooms; (3) extraction of humic materials from seawater as it relates to in situ preconcentration; (4) the distribution of dissolved hydrocarbons using in situ techniques; and (5) distribution of copper in the North Atlantic Ocean using the pump. Time series measurements of Cu made during phytoplankton blooms suggest that there is little transfer of Cu to forms extractable by reverse phase techniques, despite increases in extractable chelators. Cadmium shows evidence of removal by particles under these conditions, as shown by an 80% decrease in the dissolved Cd concentration and an increase in particulate Cd and Cd flux. The extraction of humic materials from seawater using XAD-2 by acidification and non-acidification of the samples suggest that quantitative and qualitative differences in the extracted materials exists. More than twice as much organic material was extracted when the samples were acidified. Light absorption and copper binding capacity were similar for both extracts; however, the non-acidified extracts possessed a lower average molecular weight and contained a different suite of compounds as determined by TLC studies. An in situ pre-acidification device consisting of a column of a cation exchange resin was tested and found to extract organic material which is physically and chemically similar to the HCl acidified extracts. Measurements of dissolved hydrocarbon concentrations in the North Atlantic (20-180 ng/l) are considerably lower than have been previously reported. This result suggested that significant contamination problems still exist in conventional hydrocarbon sampling methods. In situ techniques were used to determine the concentration of dissolved copper and organo-copper complexes in the North Atlantic Ocean. The concentrations (ca. 1 nM) agree well with much of the data previously published which measured dissolved Cu using conventional rigorous cleaning and sampling techniques. Thesis (Ph.D.)--Dalhousie University (Canada), 1991.