No description available.

No description available.

Mining industry has been identified as the main sustenance of the South African economy, however the negative impacts of the industry on the ecological systems cannot be over emphasized due to the released waste which is mostly heavy metals into the environment. The study evaluated six heavy metal (A1, Cu, Fe, Ni, Pb and Cr) contents in a tailings dam from a specific mine site. Two sets of samples for the investigation were measured, that is, one in year 2012 and the other in year 2013. In the year 2012, the sample set was only taken at a distance profile of 500 meters from the foot of the dam, whereas the sample set taken in the year 2013 was for the 500 and 1500 meter distance profiles from the foot of the dam. The year 2012 and 2013 sample sets for the 500m distance profile were sampled very similarly to each other. A kilogram of each sample was taken as per grid format. The samples at varied depths were taken at 0-cm depth for the top layer, 20cm depth for the second layer, and 30cm depth for the third layer. The samples for the surface varied distance were taken at 1 m, 2m, 3m, and 4m away from each 500m and 1500 sampling points. The 2012 samples were analysed using characterization methods namely ICP MS and The 2013 samples were analysed using the ICP OES. The comparison of the field results for the six heavy metals studied (A1, Fe, Pb, Cu, Ni and Cr) was performed using statistical analytical methods, namely ANOVA. The statistical analysis results for heavy metals (A1, Fe, Pb, Cu, Ni and Cr) from sample and 2013 revealed that the group means are not significantly different from each other which means that there is no significant difference in (A1, Fe, Pb, Cu, Ni and Cr) concentrations with respect to both depth and distance. The observations from both 2012 and 2013 indicate the results of the samples are in agreement. In addition, the comparative average concentrations of the three results obtained reach the same conclusion that the tailing dam probably does not introduce considerable or significant amounts of these metals (A1, Fe, Pb, Cu, Ni and Cr) into the surrounding soils. / Chemical Engineering / M. Tech. (Chemical Engineering)

published_or_final_version / Ecology and Biodiversity / Master / Master of Philosophy

Biosorption is a property of certain type of inactive, microbial biomass to bind and concentrate heavy metals from even very dilute aqueous solutions. Biomass exhibits this property, acting just as a chemical substance, as an ion exchanger of biological origin. It is particularly the cell wall structure of certain algae that is found responsible for this phenomenon. In these experiments, the rate and extent for removal of copper is subjected to parameters such as pH, initial metal concentration, biosorbent size, contact time, temperature and the ability of the biomass to be regenerated in sorption-desorption experiments. The metal adsorption was found to be rapid within 25 minutes. The maximum copper uptake of 30 mg of copper / g of biomass has been observed, in the following conditions: 100 mg / L, 0.1 g of biomass, pH 4 and at temperature of 25°C. From this study, it was found that copper uptake is increasing with increase in pH, with optimum being pH 4. Copper uptake increases substantially from 0 to 25 minutes. Metal biosorption behaviour of raw seaweed Sargassum in six consecutive sorptiondesorption cycles were also investigated in a packed-bed column, during a continuous removal of copper from a 35 mg/l aqueous solution at pH 4. The sorption and desorption was carried out for an average of 85 and 15 hours, respectively, representing more than 40 days of continuous use of the biosorbent. The weight loss ofbiomass after this time was 13.5%. The column service time decreased from 25 hrs in the first cycle to 10 hrs for the last cycle. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2005.

Mining industry has been identified as the main sustenance of the South African economy, however the negative impacts of the industry on the ecological systems cannot be over emphasized due to the released waste which is mostly heavy metals into the environment. The study evaluated six heavy metal (A1, Cu, Fe, Ni, Pb and Cr) contents in a tailings dam from a specific mine site. Two sets of samples for the investigation were measured, that is, one in year 2012 and the other in year 2013. In the year 2012, the sample set was only taken at a distance profile of 500 meters from the foot of the dam, whereas the sample set taken in the year 2013 was for the 500 and 1500 meter distance profiles from the foot of the dam. The year 2012 and 2013 sample sets for the 500m distance profile were sampled very similarly to each other. A kilogram of each sample was taken as per grid format. The samples at varied depths were taken at 0-cm depth for the top layer, 20cm depth for the second layer, and 30cm depth for the third layer. The samples for the surface varied distance were taken at 1 m, 2m, 3m, and 4m away from each 500m and 1500 sampling points. The 2012 samples were analysed using characterization methods namely ICP MS and The 2013 samples were analysed using the ICP OES. The comparison of the field results for the six heavy metals studied (A1, Fe, Pb, Cu, Ni and Cr) was performed using statistical analytical methods, namely ANOVA. The statistical analysis results for heavy metals (A1, Fe, Pb, Cu, Ni and Cr) from sample and 2013 revealed that the group means are not significantly different from each other which means that there is no significant difference in (A1, Fe, Pb, Cu, Ni and Cr) concentrations with respect to both depth and distance. The observations from both 2012 and 2013 indicate the results of the samples are in agreement. In addition, the comparative average concentrations of the three results obtained reach the same conclusion that the tailing dam probably does not introduce considerable or significant amounts of these metals (A1, Fe, Pb, Cu, Ni and Cr) into the surrounding soils. / Chemical Engineering / M. Tech. (Chemical Engineering)

A research project submitted to the Faculty of Sciences, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science in Environmental Sciences (Coursework and Research Report). Johannesburg, 2016. / Paenibacillus castaneae isolated from acid mine decant (Gauteng, South Africa) was previously shown to tolerate high concentrations of lead (Pb). The ability of the bacterium to tolerate/resist other heavy metals is probable and suggests a role for P. castaneae as a biosorbent for their removal from contaminated wastewaters. The current study aimed at determining whether the bacterium is also resistant to other common metal contaminants specifically, zinc (Zn) and nickel (Ni), found in South African wastewaters for biosorption by P. castaneae. Additionally, the influence of the external factors pH and competing cations on the uptake of these metals by the bacterium was evaluated. Specific rates of metal uptake (Q) were calculated indirectly from quantifying (by spectroscopy) the residual ion concentrations post exposure to 3 mM metal after various treatments. P. castaneae was found to tolerate Zn but showed vulnerability towards Ni. In a binary metal system, the bacterium showed a preferential metal uptake in the order Zn>>Co> Mn with a highest Q of 26 mg Zn/g biosorbent biomass recorded in the presence of Mn at pH 7. On the contrary, in a multimetal complex solution, the order of preference shifted to Co>>Zn with no absorption of Mn at the same pH. The results indicate that both pH and the presence of cations have an effect on the uptake of Zn by P. castaneae that could favour or inhibit its biosorption. The present study confirms the ability of P. castaneae to remove additional metals such as Zn, Mn and Co. These findings further suggest the potential of P. castaneae as a biosorbent for greener clean-up strategies of contaminated water facilities around Gauteng in the way of bioremediation. Keywords: P. castaneae, biosorption, specific metal uptake, zinc, lead, nickel / LG2017

No description available.

No description available.

Deep Bay is located in the northwestern coast of Hong Kong (HK), where brackish water from the Pearl River Estuary meets and interacts with fresh water from Shenzhen River and Yuen Long Creek. A review of published material in this study indicates rapid economic and industrial developments can be found in Hong Kong and Pearl River Delta (PRD) region in the last 60years, which would have contaminated the sediment in Deep Bay with heavy metals. To examine the nature of metal contamination history, two 2m-long sediment cores are collected from the mud flat of Deep Bay, and the chemical and physical properties of the sediment sequence analyzed. Small disturbance of sediment profile is observed by the fluctuation of 210Pb signal, and constant rate of supply (CRS) model is applied for the calculation of sedimentation rate which is estimated to be 1.82cm/year.137Cs dating resolves two peaks for the radionuclide at 28cm and 109cm, as well as the onset of excessive 137Cs activity at 135cm, which are connected to the Chernobyl accident in 1986 and the banning and beginning of atmospheric testing of nuclear weapons in 1963 and 1950 respectively. Particle size analysis shows the core sediments are predominantly silt (4-64μm) and clay(<4μm). Enrichment factor of metal concentration displays that Cd, Cr, Cu and Zn has been significantly enriched since the 1950s, and hence 3 phases of metal enrichment could be identified: 1) insignificant anthropogenic input in preindustrial period before 1950, 2) significant enrichment of metal from anthropogenic sources during industrial stage in HK from 1950 to 1980, and 3) a further increase of metal enrichment after the introduction of new town development in northwestern part of HK and Chinese economic reform since 1980. Among the metals in the sediments at depth over 70cm, Cu and Zn are found to be exceeded the Lower Chemical Exceedance Level of the sediment quality criteria given by the Hong Kong Environmental Protection Department; hence, the metals would impose threats to the natural environment once they are released back to water column by changes to physical conditions. To evaluate the extent of environmental threats, future studies could focus on the bioavailability of the metals and the interaction of metals in sediments and water with organisms in the ecosystem of Deep Bay. / published_or_final_version / Earth Sciences / Master / Master of Philosophy