Thesis (MTech (Physical Sciences))--Peninsula Technikon, Cape Town, 1999. / Wet deposition of toxic trace metals is the dominant mode of deposition in terrestrial ecosystems and contributes very significantly to their pollution burden. Wet deposited metals are dissolved in rainwater. They reach the vegatation in a form most favourable for uptake. Reliable analysis of toxic trace metals in rainwater is important in order to determine the impact they make on the environment. In this study, trace metals in rainwater and in dry deposition (as a control measure), have been analysed over a period of a year. These metals include cadmium, copper, cobalt, lead, nickel and zinc. The rainwater was filtered, acidified to pH2 and irradiated with UV-light. Dry deposition samples, were digested by heating in nitric acid before analysis. Differential-pulse anodic stripping voltammetry was used to determine cadmium, lead and zinc. Copper was determined by adsorptive cathodic stripping at pH7 after complexation with catechol. Cobalt and nickel were measured at pH9 by adsorptive cathodic stripping after formation of their dimethylglyoximes. Sampling was done on a daily basis from April 1996 to March 1997, on the campus of the Peninsula Technikon. The samples were collected over a 24-hour period. The total average concentration for the metals was 16.11 flg/dm3 for rainwater and 427flg/dm3 for dry deposition. Meteorological factors such as wind speed, humidity and temperature affect the distribution of pollutants and thus the trace metal levels. The levels of the metallic pollutants were thus evaluated against meteorological data. Differential-pulse stripping voltammetry is shown to be applicable for heavy metal analysis of rainwater.

Thesis (MTech (Chemistry))--Peninsula Technikon, Cape Town, 1995 / An analytical method using Differential Pulse Anodic Stripping Voltammetry was developed for determining trace quantities of Cu, Pb, Cd and Zn in airborne particulate matter. The levels of the metallic pollutants were evaluated against meteorological data. Instrumental parameters and sample processing were optimised for determining the metals in the concentration range 1 to 40 μg/l with a percentage relative standard deviation (%RSD) less than 10%. Airborne particulate matter was decomposed by heating in a mixture of Hydrochloric and Sulphuric acids. Recovery studies were used to evaluate the digestion procedure, in the absence of a suitable reference material. The percentage recovery for the metals were between 95% and 100%. A total of 77 air samples were collected from January to December 1992, on the campus of the Peninsula Technikon. The samples were collected over 24 hour periods by filtration at a sampling rate of 20 liters per minute. The total average concentration for the metals was 25.3μg/m³. . No Cd was detected in any of the samples.

by Li Sze Kwan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1990. / Bibliography: leaves 234-259. / ACKNOWLEDGEMENT --- p.i / ABSTRACT --- p.ii / CONTENTS : / Chapter CHAPTER 1: --- GENERAL INTRODUCTION --- p.1 / Chapter 1.1 --- Our Environment Is Polluted --- p.1 / Chapter 1.2 --- Heavy Metal Contamination --- p.3 / Chapter 1.3 --- The Effect of Cadmium and Some Related Metals on Environment --- p.5 / Chapter 1.4 --- The Uses of Microorganisms in Cleaning Up Environment --- p.9 / Chapter 1.5 --- Mechanisms of Cadmium Uptake in Cadmium Accumulating Strains --- p.10 / Chapter 1.6 --- Techniques for Cell Immobilization --- p.13 / Chapter 1.7 --- Prospect --- p.20 / Chapter CHAPTER 2: --- ISOLATION OF CADMUIM ACCUMULATNIG MICROORGANISMS --- p.22 / Chapter 2.1 --- Introduction --- p.22 / Chapter 2.2 --- Materials and Methods --- p.25 / Chapter 2.2.1 --- Recipes Used for Growing Various Organisms --- p.25 / Chapter 2.2.2 --- Methods Used for Collecting Organisms to be Tested --- p.27 / Chapter 2.2.3 --- Observation of Samples by Microscope --- p.28 / Chapter 2.2.4 --- Enrichment of Cadmium Resistant Microorganisms --- p.28 / Chapter 2.2.5 --- Selection and Isolation of Cadmium Resistant Microorganisms --- p.29 / Chapter 2.2.6 --- Purification of Microbial Colonies --- p.30 / Chapter 2.2.7 --- Preliminary Classification of Selected Microorganisms --- p.30 / Chapter 2.2.8 --- Screening of Cadmium Accumulating Strains --- p.30 / Chapter 2.2.9 --- Cadmium Analysis --- p.31 / Chapter 2.3 --- Result --- p.32 / Chapter 2.3.1 --- Selection of Cadmium Resistant --- p.32 / Chapter 2.3.2 --- Cadmium Resistance of Isolates --- p.36 / Chapter 2.3.3 --- Screening of Cadmium Accumulating Microorganisms --- p.38 / Chapter 2.4 --- Discussion --- p.39 / Chapter CHAPTER 3: --- GENERAL CHARACTERIZATION OF STRAIN 1000A --- p.43 / Chapter 3.1 --- Introduction --- p.43 / Chapter 3.1.1 --- Various Factors Affecting the Accumulation of Cadmium of Strain 1000A --- p.43 / Chapter 3.1.2 --- Identification --- p.44 / Chapter 3.2 --- Materials and Methods --- p.45 / Chapter 3.2.1 --- "Preparation of Solutions, Antibiotics and Reagents" --- p.45 / Chapter 3.2.2 --- Culture Media Used --- p.47 / Chapter 3.2.3 --- Growth Kenetics Determination --- p.48 / Chapter 3.2.4 --- Determination of the Effect of Cadmium Concentration on Cd-uptake in Free Cells --- p.49 / Chapter 3.2.5 --- Determination of the Effect of Phosphate Concentration on Cd-uptake in Free Cell --- p.49 / Chapter 3.2.6 --- Determination of the Cd-uptake in Free Cells in Continuous Cultures --- p.50 / Chapter 3.2.7 --- Determination of Antibiotic Resistance of Strain 1000A --- p.51 / Chapter 3.2.8 --- Dstermination of Relationship between Chloramphenicol Resistance and Cd-uptake --- p.52 / Chapter 3.2.9 --- Cadmium Analysis --- p.52 / Chapter 3.2.10 --- Determination of Inorganic Precipitation of Cadmium --- p.53 / Chapter 3.2.11 --- Assimilation Tests --- p.54 / Chapter 3.2.12 --- Identification of Strain 1000A --- p.55 / Chapter 3.3 --- Result --- p.55 / Chapter 3.3.1 --- Growth Kinetics of Strain 1000A in Cadmium Supplemented Peptone Medium --- p.55 / Chapter 3.3.2 --- Cd-uptake of Strain 1000A at Various Cadiuin Concentration --- p.65 / Chapter 3.3.3 --- Effect of Phosphate concentration on Cd-uptake of Strain 1000A --- p.65 / Chapter 3.3.4 --- Cd-uptake of Strain 1000A in Continuous Cultures --- p.70 / Chapter 3.3.5 --- Inorganic Precipitation of Cadmium Phosphate --- p.75 / Chapter 3.3.6 --- Determination of Antibiotic-Resistance of Strain 1000A --- p.78 / Chapter 3.3.7 --- Effect of Chloramphenicol on Cd-uptake and Cadmium Resistance of Strain 1000A --- p.82 / Chapter 3.3.8 --- Determination of the Effect of Tetracyclin --- p.85 / Chapter 3.3.9 --- Assimilation Tests --- p.94 / Chapter 3.3.10 --- Identification of Strain 1000A --- p.94 / Chapter 3.4 --- Discussion --- p.97 / Chapter CHAPTER 4: --- DETERMINATION OF CADMIUM UPTAKE MECHANISM IN P. PICKETTI 1000A --- p.102 / Chapter 4.1 --- Introduction --- p.102 / Chapter 4.2 --- Materials and Methods --- p.105 / Chapter 4.2.1 --- Preparation of Solutions and Reagents --- p.105 / Chapter 4.2.2 --- Preparation of Reagents for SDS-PAGE --- p.105 / Chapter 4.2.3 --- Recipes for Growing Cells --- p.107 / Chapter 4.2.4 --- Protein Determination --- p.108 / Chapter 4.2.5 --- Examination of Cadmium Accommodation in P. picketti 1000A by Transmission Electron Microscope --- p.108 / Chapter 4.2.6 --- SDS-polyacrylamide Gel Electrophoretic Determination of Protein Profiles --- p.109 / Chapter 4.2.7 --- Phosphate Assay --- p.111 / Chapter 4.2.8 --- Orthophosphate Estimation --- p.112 / Chapter 4.2.9 --- Sulphide Analysis --- p.112 / Chapter 4.2.10 --- Cadmium Analysis --- p.113 / Chapter 4.2.11 --- Cd-binding Determination through Column Separation --- p.113 / Chapter 4.2.12 --- Cd-binding Determinate ion through SDS Electrophoresis --- p.114 / Chapter 4.2.13 --- Determination of Cadmium Distribution of Cells --- p.115 / Chapter 4.3 --- Result --- p.116 / Chapter 4.3.1 --- SDS-PAGE Determination of Protein Profiles of P. picketti 1000A --- p.116 / Chapter 4.3.2 --- Determination of Cd-binding Protein of P. picketti 1000A --- p.121 / Chapter 4.3.3 --- "Determination of the Relationship of Cellular Cadmium, Sulphide and Phosphate" --- p.131 / Chapter 4.3.4 --- Examination of Cadmium Accumulation of P. picketti 1000A by Transmission Electron Microscope --- p.142 / Chapter 4.3.5 --- Cadmium Distribution of Cadmium-Accommodated Cells --- p.148 / Chapter 4.4 --- Discussion --- p.152 / Chapter CHAPTER 5: --- CORRELATION AMONG METALS IN HEAVY METAL UPTAKE --- p.158 / Chapter 5.1 --- Introduction --- p.158 / Chapter 5.2 --- Materials and Methods --- p.158 / Chapter 5.2.1 --- Preparation of Solutions --- p.159 / Chapter 5.2.2 --- "Determination of Effect of Zn+2 ," --- p.160 / Chapter 5.2.3 --- Determination of Effect of Cu+2 . --- p.161 / Chapter 5.2.4 --- "Correlation among Cd+2, Cu+2 and Zn+2" --- p.161 / Chapter 5.2.5 --- Growth Kenetics Determination --- p.162 / Chapter 5.2.6 --- Cell Sample Preparation --- p.162 / Chapter 5.2.7 --- Orthophosphate Estimation --- p.162 / Chapter 5.2.8 --- Metal Analysis --- p.163 / Chapter 5.3 --- Result --- p.163 / Chapter 5.3.1 --- Effect of Zn+2 --- p.163 / Chapter 5.3.2 --- Effect of Cu+2 --- p.173 / Chapter 5.3.3 --- "Correlation among Cd+2, Cu+2 and Zn+2" --- p.178 / Chapter 5.4 --- Discussion --- p.195 / Chapter CHAPTER 6: --- HEAVY METAL UPTAKE OF IMMOBILIZED CELL --- p.197 / Chapter 6.1 --- Introduction --- p.197 / Chapter 6.2 --- Materials and Methods --- p.199 / Chapter 6.2.1 --- Preparation of Solutions and Medium --- p.199 / Chapter 6.2.2 --- Harvesting of Cells --- p.199 / Chapter 6.2.3 --- Immobilization of Cells --- p.199 / Chapter 6.2.4 --- Determination of the Effect of Temperature --- p.200 / Chapter 6.2.5 --- Determination of Optimum Cell Concentration in Polyacrylamide Gel --- p.201 / Chapter 6.2.6 --- Determination of pH Effect on Cd-uptake --- p.201 / Chapter 6.2.7 --- Pretreatment with 70% Methanol --- p.202 / Chapter 6.2.8 --- Combined Pretreatment with Methanol and NaOH --- p.202 / Chapter 6.2.9 --- Effect of Phosphate on Cd-uptake of Immobilized Cell --- p.202 / Chapter 6.2.10 --- Comparison of Cadmium- and Copper-uptakes in Cells Immobilized in K-carrageenan and in Polyacrylamide --- p.203 / Chapter 6.3 --- Result --- p.204 / Chapter 6.3.1 --- Effect of Temperature on Cd-uptake --- p.204 / Chapter 6.3.2 --- Determination of Optimum Cell Concentration in Polyacrylamide Gel --- p.204 / Chapter 6.3.3 --- Effect of pH on Cd-uptake of Immobilized Cells --- p.207 / Chapter 6.3.4 --- Effect of Methanol on Cd-uptake --- p.210 / Chapter 6.3.5 --- Combined Effect of pH and Methanol on Cd-uptake --- p.213 / Chapter 6.3.6 --- Effect of Phosphate on Cd-uptake of Immobilized Cells --- p.213 / Chapter 6.3.7 --- Comparison between Cadmium- and Copper-uptake of Cells Immobilized in K-carrageenan and in Polyacrylamide --- p.220 / Chapter 6.4 --- Discussion --- p.228 / Chapter CHAPTER 7: --- CONCLUSION --- p.232 / REFERENCES --- p.234

Thesis (M.Sc.) -- University of Limpopo, 2005 / Six aerobic bacterial strains [GM 10(1), GM 10 (2), GM 14, GM 15, GM 16 and GM 17] were isolated from an antimony mine in South Africa. Heavy-metal resistance and biosorptive capacities of the isolates were studied. Three of the isolates (GM 15, GM 16 and GM 17) showed different degrees of resistance to antimony and arsenic oxyanions in TYG media. The most resistant isolate GM 16 showed 90 % resistance, followed by GM 17 showing 60 % resistance and GM 15 was least resistant showing 58 % resistance to 80 mM arsenate (AsO4 3-). GM 15 also showed 90 % resistance whereas isolates GM 16 and GM 17 showed 80 % and 45 % resistance respectively to 20 mM antimonate (SbO4 3-). Arsenite (AsO2 -) was the most toxic oxyanion to all the isolates. Media composition influenced the degrees of resistance of the isolates to some divalent metal ions (Zn2+, Ni2+, Co2+, Cu2+ and Cd2+). Higher resistances were found in MH than in TYG media. All the isolates could tolerate up to 5 mM of the divalent metal ions in MH media, but in TYG media, they could only survive at concentrations below 1 mM. Also, from the toxicity studies, high MICs were observed in MH media than TRIS-buffered mineral salt media. Zn2+ was the most tolerated metal by all the isolates while Co2+ was toxic to the isolates. The biosorptive capacities of the isolates were studied in MH medium containing different concentrations of the metal ions, and the residual metal ions were determined using atomic absorption spectroscopy. GM 16 was effective in the removal of Cu2+ and Cd2+ from the contaminated medium. It was capable of removing 65 % of Cu2+ and 48 % of Cd2+ when the initial concentrations were 100 mg/l, whereas GM 15 was found to be effective in the biosorption of Ni2+ from the aqueous solutions. It was capable of removing 44 % of Ni2+ when the initial concentration was 50 mg/l. GM 17 could only remove 20 % of Cu2+ or Cd2+. These observations indicated that GM 16 could be used for bioremediation of xvi Cu2+ and Cd2+ ions from Cu2+ and Cd2+-contaminated aqueous environment, whereas GM 15 could be used for bioremediation of Ni2+. / National Research Foundation and the University of the North Research Unit

No description available.

The mixed metal compound, Chromated Copper Arsenate, or CCA, has been widely used as a wood preservative. The metal ions in CCA, CrO��������, Cu�����, and AsO��������, have been found in contaminated surface and subsurface soils and groundwater nearby some wood preservative facilities and nearby wood structures. Iron oxides are a ubiquitous soil-coating constituent and are believed to be a main factor in controlling the transport and fate of many metals in the soil solution. In this research, iron-oxide-coated sand (IOCS) is used as a surrogate soil to investigate the adsorption and transport behavior of the mixed metals solution, copper, chromate, and arsenate, in the subsurface environment. Copper adsorption increases with increasing pH. The presence of arsenate in the solution slightly increases, while chromate has minimal effect, on the amount of copper adsorbed. Chromate adsorption decreases with increasing pH. With arsenate present in solution, chromate adsorption is significantly suppressed over the pH range studied. In contrast, the presence of copper slightly increases chromate adsorption. Similar to chromate, arsenate adsorption decreases with increasing pH. The presence of chromate or copper does not affect the amount of arsenate adsorbed over the range of concentrations studied. Two surface complexation models, the triple layer model (TLM) and the electrostatic implicit model (EIM), were used to simulate equilibrium adsorption in both single-metal and multi-metal systems. Simulations using the specific surface complexation equilibrium constants derived from either the single-metal or the multi-metal systems with both the TLM and the EIM were successful in fitting the adsorption data in that respective single or multi-metal system. The local equilibrium assumption using batch-derived sorption isotherm parameters from the EIM failed to predict the copper and arsenate transport, while it adequately described chromate transport. The breakthrough curves of all three metals were asymmetrical and showed long-tailing behavior. This nonideal behavior is caused by nonlinear sorption and/or non-equilibrium conditions during transport. The two-site chemical non-equilibrium model, which accounts for the kinetically controlled adsorption sites, was able to fit the observed breakthrough curves for all three metals in single-metal systems. However, the model was partially successful in predicting transport in multi-metal systems. / Graduation date: 2002

Succinic acid, a low molecular weight dicarboxylic acid was used to leach out heavy metals from Willamette Valley soil (contaminated separately with lead, copper, and zinc) in form of water-soluble organo-metal complexes. The research tasks included developing synthetic contaminated soils representative of those found at Superfund sites and making heavy metal adsorption and desorption studies. Fixed amounts of single-metal contaminated soil were treated with succinic acid under varying conditions of pH and organic ligand concentration. Based on the total metal mobilized into the aqueous phase, the optimum values of pH and organic acid were established for each metal. Since the direct determination of all species solubilized by the organic acid solution was not possible, a computer speciation program called MICROQL was used to determine the concentration of metal species in solution containing several metals and potential ligands. The results indicate that succinic acid is capable of significantly altering the partitioning of metals between the soil and the aqueous phase. Higher concentrations of the organic acid resulted in higher removal of metal from the soil. In case of lead and copper, low pH (3.5) succinic acid flushing solution was found to be the most effective, while a pH range of 4.5-5.5 was deemed optimum for zinc. The results also established that the extent of removal of any metal depended not only upon the the stability constant of the organo-metal complex, but also on its mode of retention within the soil. / Graduation date: 1993

published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

No description available.

Weak organic acids and/or their salts were tested as soil washing or flushing agents for the ex- or in-situ remediation of soils polluted by heavy metals. Three soils naturally with heavy metals were used for the tea. / The three soils were characterized as a clay loam, loam and sandy clay loam. Their organic matter, pH, saturated hydraulic conductivity, cation exchange capacity, particle density and heavy metal contents were also characterized. The different retention forms of heavy metals in all 3 soils were studied by sequential extraction. The clay loam was contaminated with Cr, Hg, Mn and Pb while the loam and sandy clay loam were contaminated with Cd, Pb, Cu and Zn. Weak organic adds and/or their salts and chelating agents (EDTA and DTPA) were used at different pH, levels of concentration and leaching time in batch experiments to establish optimum conditions for maximum removal of heavy metals from the three soils. Citrate and tartarate were found to be quite effective, in leaching heavy metals from these soils. The rate of leaching of heavy metals from soils with citrate, tartarate and EDTA was modeled using two-reaction model at a constant pH and temperature. / Three contaminated soils of different textures were flushed in a column at optimum pH with a salt of weak organic acids, namely, citrate, tartarate, citrate+oxalate or a chelating agent such as EDTA and DTPA. The citrate and tartarate (ammonium salts) were found to be quite effective in removing heavy metals from the three contaminated soils while leaching little macronutrients and improving the soil's structure. An in-situ soil remediation simulation was also successfully tested using the sandy clay loam at large scale level in a tub (plastic container) using citrate as a flushing liquid. EDTA and DTPA were effective in removing the heavy metals except for Hg, but these strong chelating agents extracted important quantities of macronutrients from the soil. These chelating agents are also known to pollute the soil by being adsorbed on the soil particles. / A bioremediation process was developed using the fungus Aspergillus niger to produce weak organic acids (mainly citrate and partly oxalate depending on pH) for the leaching of heavy metals from contaminated soils. The fungus was cultivated on the surface of the three contaminated soils for 15 days at 30°C and a pH ≤ 4 to enhance the production of citric acid rather than oxalic acid which hinders Pb leaching. By extrapolating the result, the three contaminated soils were expected to be sufficiently remediated to meet the A category (Quebec clean up criteria for cleaning soils contaminated by heavy metals) after 20 to 25 days of leaching using this technique. / Finally, the leachate, collected following the soil remediation using weak organic acids and/or their salts, EDTA and DTPA was treated effectively using granular activated carbon.