The major purpose of this study was to examine the physiological basis of the differences in the early life histories of pink Oncorhynchus gorbuscha, chum O. keta, coho O. kisutch, chinook O. tshawytscha and sockeye O. nerka. To this end, the following working hypotheses were tested: (i) the embryo, alevin and fry of pink and chum salmon are euryhaline, whereas the same life stages of coho, chinook and sockeye are stenohaline and (ii) the euryhalinity of pink and chum is due not to high tissue tolerance but to their ability to regulate the osmotic and ionic concentrations in their blood, whereas the stenohalinity of coho, chinook and sockeye stems from their inability to osmoregulate and ion regulate. The results did not completely support these hypotheses. The LD₅₀ values and the osmoregulatory data obtained from embryos indicated that pink and chum are not euryhaline as hypothesized but like coho, chinook and sockeye embryos are stenohaline. However, pink and chum embryos showed significantly greater salinity resistance and osmoregulatory ability than embryos of the other species. The data obtained from alevins also did not support the working hypothesis for alevins of all five species were found to be stenohaline. But, as in the case for embryos, pink and chum alevins showed greater salinity resistance and osmoregulatory abilities than coho and sockeye alevins. This ability of pink and chum was correlated with better ionic regulation of sodium and chloride. Although chinook alevins survived considerably longer in 31.8 °/oo sea water than coho and sockeye alevins , their ability to osmoregulate and ion regulatewas not very different from that of coho and sockeye alevins. It was concluded, therefore, that the greater salinity resistance of chinook alevins was due to high tissue tolerance. Contrary to the results with embryos and alevins, the data obtained from fry supported the working hypotheses. The results showed that pink and chum were euryhaline and that this condition was due to their ability to osmoregulate and control the levels of sodium and chloride in the blood. Coho, chinook and sockeye fry were found to be stenohaline and were unable to regulate the osmotic and ionic concentrations in their blood. As in the case of alevins, chinook fry, due to higher tissue tolerance, manifested greater salinity resistance than coho and sockeye. When the data for all species of embryos and fry were grouped and compared to the alevins taken as a group, the LD₅₀ values of embryos and fry were found to be significantly greater than those of the alevins . The blood osmotic concentrations of embryos and fry exposed for the same duration in 31.8 °/oo sea water were significantly lower than the blood osmotic concentrations for alevins. It was included, therefore, that embryos and fry have greater salinity resistance than alevins because of the greater osmoregulatory ability of embryos and fry. On the basis of these results as well as information obtained from the literature, speculations were made on the phylogenetic relations within the genus Oncorhynchus. / Science, Faculty of / Zoology, Department of / Graduate

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This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

Thesis (PhD)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The equilibrium distribution coefficients of 32 metal ions [Al(llI), As(V), CdïIl), Ce(III), Ce(IV), Co(n), Cr(III), Cu(II), Fe(III), Ga(III), Ge(IV), !n(III), La(III), Mn(II), Mo(VI), Nb(V), Ni(II), Pr(III), Sb(V), Sc(III), Se(IV), Sn(IV), Ta(V), Tb(III), Te(IV), Ti(IV), Vev), W(VI), Y(III), Yb(III), Zn(lI) and Zr(IV)] on a cation exchanger (Bio- Rad® AG50W-X8) and an anion exchanger (Bio-Rad® AG1-X8) in varying oxalic acid - sulphuric acid mixtures were successfully determined. The equilibrium distribution coefficients of these selected metal ions were determined in both 0.05 M and 0.25 M oxalic acid at various concentrations of sulphuric acid (0.005 M, 0.05 M, 0.10 M, 0.25 M, 0.50 M, 1.00 M, 1.50 M and 2.00 M). Attempts to explain the sorption behaviour of the selected metal ions were made by using MINEQL+, a speciation modelling program, and the speciation systems for AI(III), Cd(II), Co(II) and Zn(lI) in varying oxalic acid - sulphuric acid mixtures were determined. Two component [Zr(IV)-La(III); AI(III)-La(III); Ga(IlI)-Zn(II); As(V)-Zn(II); Cu(II)- Ce(IV); Ga(III)-Ce(IV); Ge(IV)-Ce(III); Mo(VI)- Y(III); Nb(V)- Y(III); Ga(III)-Co(II); As(V)-Co(lI) and Fe(III)-Mn(II)] and three component [Fe(III)-Ga(III)-Zn(lI) and Zr(IV)-Ta(V)-Yb(III)] mixtures on a 10 ml or 13 ml cation exchange resin in a variety of oxalic acid - sulphuric acid mixtures were successfully separated. Two component [As(V)-Zr(IV); Co(II)-Fe(III); Ni(II)-Co(lI) and Ni(II)-Fe(III)] and three component [Ni(II)-As(V)-Se(IV); AI(III)-Zn(II)-Ge(IV) and As(V)-Cu(II)-Ge(IV)] mixtures on a 10 ml or 13 ml anion exchange resin in a variety of oxalic acid - sulphuric acid mixtures were also successfully separated and studied. It was also shown how some of the elution curves developed above could easily be adapted for radiochemical separations. Usin~ the relevant data from the above study, a separation for 68Gefrom a Ga20 target was developed according to a method based on acid dissolution of the target and chromatography on an anion exchange resin (Bio-Rad® AG1-X8). The separated 68Geshowed high radionuclidic purity and an acceptable chemical purity. / AFRIKAANSE OPSOMMING: Die ewewigsverdelingskoëffisiënte van 32 metaalione [Al(III), As(V), Cd(II), Ce(III), Ce(IV), Co(II), Cr(III), Cu(II), Fe(III), Ga(III), Ge(IV), In(III), La(III), Mn(ll), Mo(VI), Nb(V), Ni(ll), Pr(Ill), Sb(V), Sc(III), Se(IV), Sn(IV), Ta(V), Th(Ill), Te(IV), Ti(IV), vrv; W(VI), Y(III), Yb(III), Zn(lI) en Zr(IV)] op 'n katioonruiler (Bio-Rad® AG50W-X8) en 'n anioonruiler (Bio-Rad® AG1-X8) in veranderende oksaalsuurswaelsuurmengsels is met welslae bepaal. Die ewewigsverdelingskoëffisiënte van hierdie geselekteerde elemente is in beide 0.05 Men 0.25 M oksaalsuur by verskeie konsentrasies swaelsuur (0.005 M, 0.05 M, 0.10 M, 0.25 M, 0.50 M, 1.00 M, 1.50 M en 2.00 M) bepaal. Daar is gepoog om die sorpsiegedrag van die geselekteerde metaalione te verklaar deur die gebruik van MINEQL+, 'n spesiëringmodelleringsprogram, en die spesiëringsisteme vir AI(III), Cd(II), Co(II) en Zn(lI) in veranderende oksaalsuur-swaelsuurmengsels is bepaal. Tweekomponent [Zr(IV)- La(III); AI(III)-La(II!); Ga(III)-Zn(Il); As(V)-Zn(II); Cu(II)-Ce(IV); Ga(III)-Ce(IV); Ge(IV)-Ce(Il!); Mo(VI)- Y(III); Nb(V)- Y(ll!); Ga(Ill)-Co(Il); As(V)-Co(lI) en Fe(III)- Mn(II)] en driekomponent [Fe(III)-Ga(III)-Zn(ll) en Zr(IV)- Ta(V)- Yb(III)] mengsels op 'n 10 ml of 13 ml katioonruilhars in 'n verskeidenheid oksaalsuurswaelsuurmengsels is met welslae geskei. Tweekomponent [As(V)-Zr(IV); Co(II)- Fe(III); Ni(Il)-Co(lI) en Ni(II)-Fe(III)] en driekomponent [Ni(II)-As(V)-Se(IV); AI(III)-Zn(Il)-Ge(IV) en As(V)-Cu(II)-Ge(IV)] mengsels op 'n 10 ml of 13 ml anioonruilhars in 'n verskeidenheid oksaalsuur-swaelsuurmengsels is ook met welslae geskei en bestudeer. Daar is ook aangetoon hoe sommige van die elueringskrommes wat hierbo ontwikkel is, maklik vir radiochemiese skeidings aangepas sou kon word. Deur gebruik te maak van die relevante data uit die studie hierbo, is 'n skeiding vir 68Geuit 'n Ga20-teiken ontwikkel volgens 'n metode gebaseer op suurdissolusie van die teiken en chromatografie op 'n anioonruilhars (Bio-Rad® AG1-X8). Die geskeide 68Gehet hoë radionukliedsuiwerheid en 'n aanvaarbare chemiese suiwerheid getoon.

A Thesis presented in the University of the Witwatersrand, Johannesburg for the degree of Doctor of Philosophy, 1953 / Investigations have been carried out into the life of various Anion Exchange Resins employed on the Rand for the extraction of uranium from the uranium Leach Liquors. It was found that in the case of the leach liquors produced at the western Reefs pilot plant and at the West Rand Consolidated Uranium plant, the major factor causing a decrease in the efficiency of the Ion exchange resins was the presence of certain chemical poisons in these pregnant solutions. [No abstract provided. Information taken from General Summary] / AC2017