Licentiatavhandling (sammanfattning) Linköping : Linköpings universitet, 2006. / Härtill 2 uppsatser.

Diss. (sammanfattning) Linköping : Univ. / Härtill 5 uppsatser.

Thesis (Ph. D.)--College of William and Mary. / Typescript (photocopy). Vita. Includes bibliographical references.

The conversion of arsenic into organoarsenic compounds is affected by the action of organisms, particularly marine organisms. These arsenic species require a suitable technique to distinguish the species and quantify their abundance. The ICP-MS coupled to either HPLC or HG-CT are the most popular techniques for arsenic species could be separated, but the limit of detection (LOD) was not satisfactory for the concentration of arsenic in natural waters and the chloride interference in the marine samples was high. While the HG-CT-ICP-MS, the LOD was sufficient to detect very low concentrations of arsenic, particularly for methylated arsenic species, and there was no chloride interference, however the inorganic arsenic in the reagents was high and only the reducible arsenic species could be detected. The transformation of organoarsenic compounds, specifically the conversion of arsenosugars by micro-organisms in sediment, was studied by analysing porewater from decaying seaweed in a mesocosm experiment. Arsenosugars degraded to DMAE further to DMAA to MMAA and finally to As(V) and As(III), but not as previously proposed to AsB, AsC and TMAO. Arsenic was released by the dissolution of manganese and iron clay particles in a pristine area but much more by anaerobic degradation in an industrial area. Arsenic was removed from the water phase to the sediment by precipitation, particularly with manganese at the surface sediment only in the pristine area but with iron in the industrial area.

No description available.

Thesis (Ph. D.)--Oregon State University, 1973. / Typescript (photocopy). Includes bibliographical references. Also available via the World Wide Web.

Thesis (Ph. D.)--Oregon State University, 1981. / Typescript (photocopy). Includes bibliographical references (leaves 153-160). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 1980. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 1983. / Typescript (photocopy). Includes bibliographical references (leaves 121-125). Also available on the World Wide Web.

In this paper we developed an automatic sampling device which is capable of taking samples of the substrates at pre-programmed schedule and storing the samples for retrieval. For the reason that the sampler is operated in a severe ocean environment, the first design consideration is to use mechanisms and parts as simple as possible to reduce the risk of failure. Another primary concern is to make sure the design can preserve sediment securely in water. Besides, other considerations include size, weight, and functions of programmable sequential sampling. The sampling device is developed in two phases. Firstly, a device equipped with only one sampler is designed for achieving the purpose of programmable sampling. Secondly, the design will be extended to have multiple samplers to accomplish the task of sequential sampling. Six main designs are implemented in the first stage. They are the conceptual design of the grab for taking and storing sediment, the design of separation and reunion between grab and transmission mechanism, gearing design for transmitting motion of the sampler, timer and control circuit design for the lowest power consuming consideration, pressure hull design for installing a motor, batteries, and needed electric devices, and frame design for firmly supporting all instruments. The design of phase one was completed and its preliminary testing result came out successfully except that the collection chamber is not sealed securely enough. A new sample holder was designed and then successfully solved the problem of sediment sealing. According to the design of phase one, the concept design of the sequential sampling device of having 24 sample holders is presented.