Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 130-139).

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1980. / Supervised by Charles D. Hollister. Includes bibliographical references (leaves 206-211).

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1980. / Supervised by John W. Farrington. Vita. Includes bibliographical references (leaves 231-243).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. Includes bibliographical references (leaves [183]-193).

Thesis (M.S.) in Civil Engineering--University of Maine, 2006. / Includes vita. Includes bibliographical references (leaves 84-87).

Thesis (Ph. D.)--University of Rhode Island, 2006. / Typescript. Includes bibliographical references (leaves 175-188).

No description available.

The farming of Atlantic salmon (Salmo salar) is challenged by parasitic infestations caused by Lepeophthreirus salmonis and Caligus elongatus. A convenient and effective way to control sea lice and treat farmed salmon is by in-feed treatments such as Slice®. A reliable, accurate and reproducible method for the determination of emamectin benzoate (EB), the active ingredient of Slice®, and its desmethylamino metabolite (DES) in sediment was developed and validated. It involved methanolic extraction, clean-up using solid-phase extraction with a strong cation exchanger, and derivatisation with trifluoroacetic acid anhydride and N-methylimidazole. Analytes were quantified following HPLC separation with fluorescence detection. The method was successfully applied to determine EB and DES in salmon flesh and skin, seawater, mussels (Mytilus edulis) and seaweed (Palmaria palmata). A laboratory study showed that EB was persistent under anaerobic conditions in two different sediments at 4 and 14 ºC. A further study also demonstrated that the growth of seaweed (P. palmata) was not affected by the presence of EB and that EB did not accumulate significantly in the seaweed. This result is encouraging in view of proposed polyculture systems involving seaweeds. Studies conducted on a working Scottish salmon farm investigated the fate of EB and DES in target and non-target matrices. For three months post-treatment, EB was detected, by mass in descending order, in the salmon flesh, skin, faeces, then mucus and sea lice with concentrations in each matrix declining steadily over the period. As EB had never been quantified in sea lice before, it was unclear whether they were a significant sink for EB in the environment, following their exposure to the medicine and dislodging from salmon after feeding. However, due to the low concentrations of EB detected in the sea lice, faeces are most probably the main route for emamectin entering the environment. Sediment collected directly below and around two active walkways, over five or six months following treatment, showed that the spatial dispersion of EB and DES was mainly limited to the area within 25 m of the cage edge, although concentrations depended on sampling location in relation to water currents. Maximum EB concentrations were recorded three months after treatment. Seven days after treatment, 6 % of the total EB input was present in the sediments within 25 m of the cage edge. Neither EB nor DES were detected in seawater, mussels, periwinkles, dogwhelks and seaweed samples collected from the walkway and the surrounding environment. This work, one of the few studies of the uptake of EB by indigenous fauna and flora of an active salmon farm, suggests that it is not significantly accumulated in matrices outwith the target organism and the sediment.

Marine sediments play an important role in the global carbon cycle, where they are ultimately important for recycling of carbon. At the sediment-water interface carbon is in constant movement both into and out of the sediment. However some environments are more important for the natural storage of carbon. Over long time scales this process has a role in climate regulation. Measuring the total O2 uptake represents a good proxy for the turnover of organic material at the sediment surface in oxygenated sediments, and equally the release of O2 represents benthic primary production. Many important biological processes are regulated by the availability of O2 at the seabed including: fauna composition and activity, phosphate exchange, nitrogen cycling and burial of organic material. Understanding of the rate and efficiency at which carbon turnover is occurring in marine sediments provides a valuable insight to the regulatory role they play in climate control. Investigation of marine sediments is best done in situ where possible, and the development of benthic “landers” has allowed measurements to be conducted at the sediment-water interface. Most recently, a novel approach known as “Eddy Correlation” (EC) has been developed. It allows quantification of the O2 exchange across any surface from simultaneous measurements of vertical velocity flow and oxygen concentration within the benthic boundary layer. The large sediment area accounted for; the high measuring frequency and the non-invasive nature are theoretical advantages over traditional methods such as benthic chamber incubations and O2 microprofiles. This study has shown that it is difficult to achieve consistent and improved measurements using EC compared to traditional methods due to the complex nature of the equipment and data analysis. Data does suggest that EC can be a strong complimentary tool for benthic carbon exchange studies. This project presents the first use of this technology across a range of benthic environments, from temperate coastal sediments and maerl beds to high-Arctic sediments and sea-ice. The method has allowed accurate quantification of the benthic remineralisation rates and carbon turnover efficiency in the coastal and maerl environments, but less so for the more complex under sea ice and cold Arctic environments. Rates presented agree well with other published studies documenting the use of this state-of-the-art technology.

This study investigated the process by which molybdenum was removed from sea water in Saanich Inlet, an anoxic fjord, whose basin sediments are enriched in molybdenum. Water samples were collected in the inlet from July 1971 to April 1972 at about two month intervals and were analyzed for pH, salinity, temperature, dissolved and suspended molybdenum, suspended manganese and iron, and dissolved oxygen and hydrogen sulphide. A new technique for the determination of dissolved and suspended molybdenum was developed. The data showed a negative correlation between dissolved molybdenum and suspended manganese, and a positive correlation between suspended molybdenum and suspended manganese. This suggested that molybdenum was being scavenged from sea water by suspended manganese oxides. The distribution of molybdenum in the basin surface sediments was qualitatively correlated to the distribution of suspended molybdenum in the overlying basin water. During about September to December, the molybdenum profile was described by a two layer system. In the top 75 m layer the molybdenum followed the salinity profile. Below 75 m the distribution was described by a one dimensional mathematical model. The yearly deposition of molybdenum in the basin sediments was calculated from the estimated sediment deposition rate. This value was not inconsistent with that calculated from the rate molybdenum is scavenged by manganese oxides from the basin water. / Science, Faculty of / Chemistry, Department of / Graduate