Variabilities of hydraulic and solute transport properties of soil are examined at three scales: pore-scale, sample volume-scale, and field-scale. Undisturbed soil cores were taken at 19 subsites spaced logarithmically along a 150 m line transect in a Groseclose mapping unit near Blacksburg; Virginia. Three core sizes were taken at each subsite at the soil surface and 0.5 m depth. 'Small' cores were-40x54 mm; 'medium' cores were 60X100 mm; and 'large' cores were 100x150 mm. Macropore effects on solute transport were evaluated using monocontinuum and bicontinuum models. Bicontinuum-predicted solute breakthrough curves (BTC) closely agreed with observed BTC data with mean errors of reduced concentrations </- 0.05 for 97% of the samples, Monocontinuum predicted BTC's had comparable fits with 80% of the samples having mean errors </- 0.07. The simpler monocontinuum model was chosen for estimating dispersion coefficients for all samples on the basis that seven percent error in concentration is acceptable for the purpose of making field predictions in light of high spatial variability. Sample volume did not significantly affect the low variation (coefficients of variation, (CV) of 7-20%) soil properties bulk density or moisture retention characteristics in Ap or Bt horizons. Large cores are recommended for assessing high variation (CV of 60-280%) fluid transport parameters, saturated hydraulic conductivity (Ks), pore water velocity and dispersion coefficients (D) since they yielded less variance than the smaller cores. Ranges of about 25 m were determined for log-transformed Ks and D from semivariograms. Monte Carlo simulations were used to predict field-average BTC's. / Master of Science

Soluble horseradish peroxidase (HRP) is internalized by Chinese hamster ovary cells, a cell line of fibroblastic origin (Adams et al., 1982). We have confirmed this result by showing no inhibition of uptake in the presence of divalent cation chelators (EGTA Mg or EDTA), excess (19 mg/ml) yeast mannan (an inhibitor of uptake through a mannose/N-acetylglucosamine receptor) or using periodate treated HRP. Periodate treatment destroys the ring structure of sugars on HRP which have hydroxyl groups on adjacent ring carbons, eliminating sugar mediated uptake of HRP. Once internalized, HRP is found in endocytic vesicles which by HRP-cytochemical staining, show deposits which rim the luminal face of vesicle membrane. Once HRP is in lysosomes, cytochemical deposits are luminal. To test if HRP is actually associated with vesicle membrane, a hypotonic lysis assay was used. Postnuclear supernatants (PNS) from cells pulse labeled with HRP were lysed and the percent of HRP sedimenting with a high speed membrane fraction was used as a measure of membrane association. After a pulse, >60% of the total HRP internalized was pelletable. Hypotonic lysis of a PNS at different pH and temperature showed no significant difference in "pelletability" from 4℃ to 37℃ at neutral pH and only a slight decrease in "pelletability" with increased temperature (4℃ to 37℃) at pH M.6. Binding of HRP in a membrane preparation was pH and temperature stable. Uptake of native HRP in the presence of yeast mannan (19 mg/ml) or using periodate treated HRP also had little effect on "pelletability", suggesting the absence of sugar specific binding in endocytic vesicles. Using the hypotonic lysis assay of a PNS after different chase times, HRP dissociation from membrane was observed over a 30 minute chase period. Internalized HRP in the presence of yeast mannan (19 mg/ml), intravesicular pH elevators HEPES (40 mM) or monensin (10 μM), or substances which should deplete cellular ATP NaF/KCN (2 mM /1 mM), showed no inhibition of dissociation kinetics. A chase at 17℃ inhibited dissociation of HRP over the entire 30 minute period. This HRP binding site(s) appears unique to endocytic vesicles. A minimum of four steps in transport have been identified based on their sensitivity to inhibitors. HRP transport, identified by Percoll density gradient fractionation, was inhibited at 17°C and was sensitive to pH elevators (NH₄Cl, monensin, HEPES) and ATP depletion (NaF/KCN). Inhibition of transport appeared to be independent of HRP dissociation except at early temperature sensitive step(s). These results suggest that transport inhibition may be due to an effect on a) inhibition of membrane dissociation (early step(s)) and alteration of membrane fluidity (later steps) by reduced temperature and b) transmembrane events by pH elevators and ATP depletion. / Ph. D. / incomplete_metadata

Call number: LD2668 .T4 1955 S85 / Master of Science

No description available.

Typescript. / Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries

In the light of increasing demand and diminishing supplies a sustainable urban water management for Melbourne and other cities will need to include water recycling and reuse of reclaimed water and stormwater. One key issue in stormwater reuse is the need for storage between times of collection until times of demand. Aquifer storage and recovery (ASR) would be a valuable option as it has limited space requirements and restricts loss from evaporation. However, stormwater commonly contains elevated levels of heavy metals, of which Zn and Cu are the most mobile. Stormwater also contains suspended solids, organic carbon, oxygen and nutrients, which influence the behaviour of injected metals and induce geochemical changes in the aquifer. While stormwater ASR has been practiced in limestone aquifers in South Australia, field data for sandy aquifers, which are more prevalent around Melbourne, are very limited. Risk assessment regarding the potential impact of stormwater ASR on the quality of the aquifer and groundwater resources in sandy aquifer is therefore necessary. After a characterisation of stormwater from different Melbourne catchments confirmed comparatively high concentrations of Zn and Cu in stormwater, three siliceous aquifer sediments were used in a series of batch sorption experiments as well as column experiments imitating one ASR cycle to assess the impact of different parameters on Zn and Cu behaviour. The reactive geochemical transport model PHT3D was then modified to simulate experimental results with the outlook that it could be used as a predictive tool for long term evaluation. The study showed that Zn adsorption was limited and desorption of large fractions occurred, indicating that injected amounts of Zn are mobile and would mainly be recovered. In contrast, Cu adsorption was higher and desorption was limited, indicating that injected amounts of Cu would mainly accumulate in the aquifer. The release of metals was triggered by reduction in pH, increase in ionic strength and particle mobilisation. Metal concentrations were also increased after storage phases, while minor sediment constituents, especially organic matter, significantly reduce metal mobility. The different role of dissolved and solid organic carbon is critical in understanding Cu behaviour during stormwater ASR. Pretreatment of stormwater to reduce the injection of colloids, organic carbon and metals are recommended to limit metal accumulation in the subsurface. Monitoring of water quality throughout the ASR cycle would be encouraged to validate the current findings with field data. Special attention should be paid to backflushed water quality to ensure correct disposal.

Appendix 7, (3 leaves) in pocket. Includes bibliography.

Thesis (MTech. degree in Agriculture.)--Tshwane University of Technology, 2011. / This study evaluated plant growth and symbiotic performance of four promiscuous-nodulating soybean genotypes and three commercial varieties supplied with a peat-based inoculant of Bradyrhizobium japonicum strain WB74 at three field sites in Mozambique and a pot experiment in South Africa. The sole aim was to assess whether these promiscuous-nodulating soybean genotypes can benefit from inoculation.

published_or_final_version / Civil Engineering / Master / Master of Philosophy