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The argument is advanced that the interception of particles settling within the water column provides a means of monitoring and understanding basic ocean processes. Geochemical and biological measurements on precisely dated bottom sediments and on preliminary recoveries from particle interceptor-traps provide supporting evidence.

The benthic fluxes of 24 elements and components are calculated from sediment trap fluxes and sediment accumulation rates at MANOP sites H and M in the eastern tropical North Pacific Ocean. In this paper, we focus our discussion on our data for copper. Benthic flux estimates for copper are 0.7 and 1.4 nmol/cm 2 /yr at H and M, respectively. These results compare well with estimates from another trap deployment in the Galapagos and modeling of pprewater and water column concentration data by other authors. Partitioning of near-bottom Cu flux indicates that the two sites receive similar amounts of primary Cu flux (flux from upper water column) and resuspended Cu flux. Only the site located on the East Pacific Rise (Site M) shows any input of hydrothermal Cu. At Site M, 35% of the near-bottom flux is due to some source other than primary, resuspended, or hydrothermal flux. We speculate that dissolved Cu from the sediments is readsorbed onto particles near the bottom at this site. Sequential leaching of trap material indicates that the flux of Cu associated with organic matter, using an operational definition, ranges from 56% to 84% of the trap material. This fraction of the total Cu increases with depth in the water column, probably through scavenging.

Hydrographic and sedimentological evidence is presented from the Santa Barbara Basin which indicates that turbidity currents transport sediment, benthic organisms, and seawater from depths near the sill (440–480 m) to the centre of the basin (590 m). Water collected within 2 m of the basin floor in December, 1969, had the chemical composition (notably higher oxygen and nitrate content) of water originating from the sill depth. In addition, live benthic gastropods, found only on sediment shallower than the sill, and sediment were recovered in a trap 3 m above the bottom in the centre of the basin. By January, 1970, the chemical perturbations of this bottom water were significantly dissipated. Another incident in November, 1970, in which the composition of the basin water below 550 m was changed by its apparent replacement with seawater originating from the sill depth, is discussed.

In May 1983, two short-term (2.5 d) deployments of sediment traps at 100, 300, and 500 m measured the sinking flux of mass (as dry weight), particulate organic carbon and carbonate carbon in the nearshore basins off Los Angeles. The flux of organic carbon at 100 m depth was about 15% of the mass flux and about 5% of the rate of primary production measured in the surface waters. At 500 m the flux of organic carbon had decreased to about half that at 100 m. Characteristics of the trap collections indicated a large biogenic contribution. In the second deployment, much of this appeared to be the fecal material of the pelagic red crab, Pleuroncodes. The biomass carbon of microorganisms determined by microscopy (exclusive of heterotrophic bacteria) in the surface waters was dominated by nano- and picoplankton size categories. In the sediment trap collections, total microorganism carbon comprised

Four sediment traps of radically different design were deployed in the Santa Barbara Basin for approximately 45 days. The measured fluxes ranged from 370 to 774 g m−2 yr−1 for the different designs. These values lie within flux measurements previously determined for the basin. Compared to the 25-year record (920 g m−2 yr−1), however, all fluxes determined in this experiment are somewhat low. Because this experiment was conducted during a general period of high storm activity and runoff, measurement of greater than average flux was expected. It is probable that the higher flux recorded by the sediments results from a significant input of detritus into the basin by near bottom transport. The chemical composition of trapped material was nearly identical in all four trap designs. The deep cone design, however, had a significantly lower Mn content. Since this trap was the only one in which reducing conditions were produced in the sample container, reduction and mobilization of manganese after collection is believed to have occurred. In spite of the very different designs tested, the factor of two agreement in flux determination and the compositional similarity of the material collected is encouraging for future attempts to directly measure the flux of particulates in the ocean.

SYNOPSIS. A free vehicle is a timed and weighted device released from a ship in a free fall to the ocean bottom. Instruments carried on the free vehicle have been built to take biological samples, sediment samples, water samples, and photographs, and to measure currents, tides, and temperature. The instrument then returns to the surface where it is recovered by the ship. A free vehicle system for biological sampling in the deep sea is described in detail. It consists of a mast assembly, flotation, hookline and traps, and a magnesium release attached to weights. Different types of magnesium links used include a rod, a wire on pliers, and a series of diamond-shaped beads that drop through a hole after dissolving. A deck plan for launching the free vehicle and its retrieval at sea are described.

The application of210Pb dating to an inshore marine deposit off the California coast has been successful. The amounts of unsupported210Pb annually accumulated in the Santa Barbara sediments are much greater than those from lake and glacial deposits and than the amount produced through the decay of radium in the overlying water column.

Analysis of dated oceanic sediments from the Santa Barbara Basin of the Southern California Bight has shown that deposition of polychlorinated biphenyls (PCB) began about 1945 and that DDE [1,1-dichloro-2-2-bis(p-chloro-phenyl)ethylene] first appeared in sediments deposited about 1952. Concentrations of both show a progressive increase through 1967; estimated deposition rates (in grams per square meter per year) in 1967 of DDE and PCB were 1.9 x 10(-4) and 1.2 x 10(-4), respectively.

ANNOUNCEMENTS that mercury concentrations often exceed recommended limits in some oceanic fishes, such as swordfish and tuna, have suggested the possibility that man has polluted the ocean with mercury on a massive scale1. Although there are examples of localized mercury pollution of certain fresh and coastal waters2–4, there are few data on historical levels of this metal in the marine environment distant from specific inputs such as wastewater outfalls. Here we report the concentrations of mercury observed in dated varved sediment layers from the Santa Barbara Basin covering the past 150 yr, as well as in two layers estimated to have been deposited approximately 1,500 yr BP. This basin is approximately 100 mile northwest of Los Angeles, and is sufficiently removed from densely populated areas to be protected from the concentrated effects of localized pollutant inputs. The record investigated includes layers deposited before the beginning of the California mining activity in 1849. Thus, it has been possible to compare near surface sediment concentrations of mercury with those observed in layers deposited before man could have released significant amounts of mercury directly into the California Current.

In a study of the rate of production of four species of planktonic Foraminifera in the region of the California Current it was found that their life spans are of the order of 1 month. Reproduction seems to take place mainly in the upper hundred meters. Results are in contrast to previous evidence presented in favor of yearly life cycles and maturing at great depth in other species of planktonic Foraminifera.

Phosphorite nodules occurring along the biologically productive continental margin of Peru have been dated by uranium-series methods. The radiometric ages range from late Pleistocene to Recent, indicating that phosphorities are currently forming in this area.

The present anthropogenic lead fluxes into sediments from the Santa Monica, San Pedro, and Santa Barbara basins of Southern California are, respectively, 0.9, 1.7, and 2.1 micrograms of lead per square centimeter of sea bottom per year; the natural (prepollution) rates for these three basins were, respectively, 0.24, 0.26, and 1.0 microgram of lead per square centimeter per year. Studies of isotopic composition indicate that lead pollutants in coastal sediments are derived mainly from the combustion of lead additives in gasoline.

The thickness of annual sediment laminations in the Santa Barbara Basin is compared to southern California drought-resistant tree growth and to regional indices of rainfall and temperature. The rate of sedimentation was found to be independent of temperature, but it is highly correlated with rainfall and tree growth. We suggest that sedimentation, like tree growth, is a function of the amount of rainfall in the prior seasons as well as the current season. The natural filter displayed by the sedimentation and tree-growth records can be described by a simple mathematical model which, in the case of sedimentation, can be related to upstream aggradation or to distributional processes on the shelf. The pair of laminae that constitute a single year9s sediment accumulation are directly related. This suggests that the process of detrital sediment delay and redistribution operates primarily in the marine environment. The density difference that distinguishes “winter” laminae and “summer” laminae is ascribed to the interaction of the seasonal rate of deposition and the growth of a mat-forming organism endemic to the surface sediment of the Santa Barbara Basin.

The sill depth (480 m) in the Santa Barbara Basin, California, separates two strikingly different planktonic sediment assemblages. The anaerobic part of the basin below the sill depth contains abundant aragomtic shells (pteropods and pelecy-pods) and relatively high concentrations of calcitic shells (planktonic foraminifera). In the oxygenated region above sill depth there are no aragonitic shells and concentrations of planktonic foraminifera are much reduced. Percentages of species, size classes, and morphological variants of planktonic foraminifera differ between samples from above and below the sill depth. In contrast, concentrations and faunal composition of siliceous shells (radiolarians and diatoms) apparently are essentially the same above and below the sill. The most important mechanism responsible for the differences between oxygenated and anaerobic calcareous assemblages probably is selective dissolution. Bottom transport may also be important, especially for slowly settling shells that may frequently be returned to suspension by benthomc activity in the aerobic region and consequently settle preferentially in the undisturbed anaerobic region. The accumulation rate of large planktonic fora-minifera in the anaerobic sediment provides an excellent measure of shell output. Comparison with the standing stock of planktonic foraminifera in the productive surface waters yields minimum turnover times of 2 to 3 weeks for the living planktonic foraminifera in the Santa Barbara Basin.

Large standing stocks found, characterized by high dominance, low diversity, small thin-shelled specimens, oxygen not limiting ecological factor

Titanium dioxide thin film was deposited on glass using in-house built Atmospheric Pressure Chemical Vapor Deposition. The system was capable of depositing uniform coating on a large substrate and can be scaled-up easily for industrial applications. The deposited film consists of photocatalytic anatase phase and was shown to degrade both stearic acid and ethyl cellulose contaminations that were deposited on top of the films. Various modifications were carried out to improve the UV and visible light photo-response of the TiO2 film; thermal annealing, embedding photocatalytic particles (Anatase, rutile, P25 and SrTi(1-x)FexO3), tin-doping and deposition of TiO2/SnO2 bilayer. Among these various modifications, embedding P25 nanoparticles and-tin doping showed enhancement to the degradation rate of stearic acid under UV illumination. Other modifications suffered from a loss of photoactivity cause primarily by the introduction of recombination centers and increased in grain size. DOCTOR OF PHILOSOPHY (EEE)

Since the discovery of the “Fujishima-Honda” effect almost five decades ago, research on photocatalyst effect has been extensive and wide applications have been developed. These include water-splitting, removal of volatile-organic-compounds (VOCs), as well as disinfection for improved air and water quality. In recent years, there have been increasing global awareness to adopt more environmental-friendly approaches. Therefore, photocatalytic oxidation (PCO) process provides a clean alternative for disinfection and removal of environment pollutants and industrial wastes. The current market leader, titanium dioxide (TiO2) is limited by its large bandgap of 3.2 eV to be efficient only under UV light. In this research project, a low-cost and simple process which allows large-scale preparation of nitrogen-doped TiO2 was firstly explored and presented. By oxidizing nano-sized titanium nitride (TiN) powder, mixed phase TiO2 with visible-light absorption up to 525 nm was obtained. The powder oxidized at 500 °C demonstrated good Rhodamine B and gaseous toluene removal; in addition to E. Coli killing under the illumination of fluorescent light with λ > 435 nm. High-resolution X-ray photoelectron spectroscopy (XPS) was used to investigate the binding states of the nitrogen dopants and their effects on the overall photocatalytic performance. The charge separation efficiency was also studied through the powders’ surface photovoltage spectra and enhanced separation was observed at higher annealing temperature. Next, this project explored a new, potential candidate for visible-light active semiconductor photocatalyst with tailorable bandgap; in the form of strontium titanate ferrite (Sr(Ti1-xFex)O3-δ). Based on previous successful work by our research group on high energy ball-milled Sr(Ti1-xFex)O3-δ nanopowder, the project aim was to develop a fabrication process for Sr(Ti1-xFex)O3-δ thin films using sol-gel approach. Using a modified sol-gel based on Pechini’s method of polymerizable metal complex, Sr(Ti1-xFex)O3-δ thin films for the whole range of 0 ≤ x ≤ 1 had been successfully fabricated and characterized for its potential as visible-light photocatalyst. The devised fabrication protocol had produced uniformly coated thin films with good adhesion. The thin films had nanoporous surfaces which are beneficial for applications which require large surface-to-volume ratio. Optical study revealed bandgap reduction from 3.46 eV to 1.10 eV with increasing iron content. However, evaluation of their photocatalytic potential using Rhodamine B, bis-phenol A and stearic acid did not show obvious photocatalytic reaction despite their bandgaps which are in the visible-light range. Further investigation using XPS study showed the formation of oxygen vacancies needed to maintain charge balance. These defects can act as electron traps which prevented charge transfer to the film surface. Furthermore, the electronic conductivity of the films also increased with iron content. As a result, the films were unable to retain charge carriers long enough on their surfaces for meaningful redox reactions. These were supported by the surface photovoltage spectra where the magnitude of contact potential difference due to light illumination decreased with iron content and decayed quickly. More investigations and diverse characterizations need to be explored to overcome these issues. For example, co-doping of non-metals and noble metals could help to overcome the charge imbalance due to substitution of Ti4+ with Fe3+; thereby reducing the formation of oxygen vacancies. Another method could be restricting the amount of iron content to lower doping levels to limit the formation of oxygen vacancies while still extending the bandgap sufficiently into the visible-light range. Lastly, to increase surface area, other visible-light active photocatalyst can be embedded into the nanoporous structure of the films, which serves as holding matrix. DOCTOR OF PHILOSOPHY (EEE)

Titanium Dioxide for applications as a photocatalyst has received much attention since its water splitting capability was discovered in 1972. However, the efficiency was a big drawback due to its large bandgap of 3.2 eV. Since 1990s, minded researchers have been focusing on shifting its bandgap into the visible light range so as to increase its efficiency. The various techniques utilized are not complex and cost effective. Visible light activity was not observed and efficiency remains low. Hence, its novelty through cheaper alternatives of synthesis suitable for commercialization proved to be very appealing. In this project, Chromium and Chromium Oxide doped titanium dioxide synthesized by high energy ball milling technique are studied. The high energy ball milling technique is cheap and is a solid state top-down method where breaking and making of new bonds can lead to the synthesis of novel materials suitable for photocatalysis applications. Their physical and optical characteristics were studies. A test of its photocatalytic reactivity was also investigated. The powders were then fabricated into composite films, using the modified sol-gel technique, for ease of application testing. In this method, the synthesized powders are distributed and incorporated into a film, whose conditions is symbolic to a coating on a wall. Similarly, their optical and physical properties were discussed. MASTER OF ENGINEERING (EEE)

Potential nickel ion release from nickel-titanium alloy (NiTi) in physiological fluid environment has hindered the alloy's medical application thus far. Even Ti6A14V, an established implant material, is known to release metallic ions in-vitro and in-vivo. To improve its biocompatibility, metal concentration at the surface was minimized by etching. A duplex titanium oxide, calcium phosphate (TiO/CaP) coating was the depostied by anodsng NiTi, Ti6A14V in a suitable electrolyte and subsequent imersion in simulated body fluid with three times the standard ion concentration (SBFx3). X-ray photoelectron spectroscopy (XPS) study indicates that anodic titanium oxide has thicker top TiO2 layer than those formed in air. Thickness of the dioxide layer increases with anodising coltage. Mixtures of titanium sub-oxides exist between the TiO2 and the metal substrate for all samples. The lack of typical titanium pcide (rutile, anatase) peaks during thin-film x-ray difraction (TF-XRD) analysis shows that titanium oxide formed is amorphous in nature, or with poorly ordered crystal structures of size beyond the sensitivity of the instrument. MASTER OF ENGINEERING (MPE)