MESMEG / Department of Mining and Environmental Geology / See the attached abstract below

No description available.

Sediments can act as both a sink for pollutants and a source for aquatic contaminants. Natural and human disturbances of the sediments can release the contaminants to the overlying water where bottom dwelling, or benthic, organisms may be exposed through direct contact, ingestion of sediment particles, or uptake of dissolved contaminants present in the water. Dredging, the most common remediation technology for heavy metals, exacerbates this process. The in situ use of emulsified metal has been studied for its ability to pull heavy metals from aqueous solution and from saturated soils. It has proven successful in the laboratory with removal of lead, cadmium, copper, nickel, and uranium from aqueous solution and removal of lead and cadmium from saturated spiked soils. The use of zero-valent metal particles, particularly those of zero-valent iron (Fe0), as an in situ remediation technique, is currently undergoing evaluation. The basic mechanism for removal appears to be reduction of contaminant metals followed by the subsequent precipitation of their insoluble forms. This is accompanied by the oxidation of the zero-valent metal. In the case of iron, Fe0 undergoes oxidation to Fe2+ and then to the Fe3+ state. Particulate Fe0 has been shown to precipitate Cr6+ to Cr3+ and Pb2+ undergoes reduction to Pb0. Initially, zero-valent iron filings were used to reduce the metal contaminants, but it has been shown that smaller size iron particles, such as nano-scale iron, have higher initial reduction rates as well as a higher concentration of contaminant removal per mole of iron. Emulsion liquid membrane (ELM) technology has been employed as a remediation technique for the removal of metals from wastewater where extraction and stripping processes are performed in a single operation. The ELMs are made by forming an emulsion between two immiscible liquids, such as oil and water, and are often stabilized by a surfactant. We have attempted to demonstrate the application of the combination of these two technologies through the use of emulsified zero-valent metal (EZVM) to treat sediments with heavy metal contamination. Emulsions were prepared using vegetable oil, water, Span 85, and either nanoscale Fe, 1-3 [micro]m Fe, 4 [micro]m Mg, or a 20 wt % Fe-Mg mixture. The results presented in this study demonstrate that EZVM is a viable technique for in situ remediation of heavy metals in sediments. Laboratory scale studies have shown high levels of removal of lead and cadmium from solution using emulsified zero-valent iron. Additionally, the use of emulsified magnesium has shown the ability for high levels of removal of copper, cadmium, nickel, lead, and uranium from solution. A variety of solution matrices were also explored for a lead solution including seawater, the presence of complexing agents and humic acids. Small-scale laboratory studies have shown 65% removal of lead and 45% removal of cadmium from saturated, spiked soils. A bench scale test to demonstrate the applicability of this technique in the environment revealed similar results for the removal of lead.

This study evaluates the effectiveness of molasses injection for reducing heavy metals and chlorinated solvents in a ground water plume at the Avco-Lycoming Superfund site in Williamsport, Pennsylvania. Molasses injection stimulates the respiration of microorganisms to make a more reducing environment. As the environment?s Redox potential decreases, the rate of chemical reduction increases. The concentrations of heavy metals and chlorinated solvents were monitored to evaluate the effectiveness of the molasses injection. The statistics revealed a decrease in the Oxidation-Reduction Potential in the groundwater and a reduction in hexavalent chromium and TCE concentrations in the groundwater. The Environmental Protection Agency views molasses injection as a viable technique for site remediation. Molasses injection is a form of facilitated natural attenuation. Molasses is injected into a plume to make the environment anaerobic. An anaerobic environment facilitates the microbes that breakdown trichloroethylene (TCE), trans-dichloroethylene (DCE), vinyl chloride (VC) and hexavalent chromium.

A trace metal speciation scheme proposed by Batley and Florence (1976) was applied to determine the physiochemical forms of zinc, cadmium, lead, and copper in two Central Florida highway drainage systems. The linearity and limitations of the ASV technique were also examined. The measurements showed that (a) more than 70% of the soluble Zn and Cd in all of the waters analyzed existed as liable ionic metal (b) lead was divided between labile and non-labile inorganic forms, but one particular form, PbCO3, predominated (c) a substantial fraction of copper is associated with organic colloids if humic substances are present. In addition a computerized chemical model for trace and major element speciation was applied to the waters in both drainage systems using measured average water quality for input parameters. A comparison between metal species measured by ASV and those predicted by the computer model are presented. There appears to be good agreement between the metal fractions measured in the water samples by ASV and those predicted by the chemical model.

A study was performed involving the leaching characteristics of three synthetically-generated metal finishing sludges. Three precipitates (one hydroxide, two sulfide-based) containing varying concentrations of cadmium, copper, lead, nickel and zinc were dewatered and subjected to an EPA-regulated limits. The sludge generated from an insoluble sulfide process exhibited the fewest parameters in violation (two), while the soluble sulfide sludge had one metal in compliance and the hydroxide sludge had none. On a metal-by-metal basis, the lead and copper exhibited the greatest capacity to withstand resolubilization in a low pH (5) environment. Nickel and zinc were present at the highest leachate concentrations in all three sludges. Cadmium extraction concentrations varied. In conjunction with this study, a montmorillonite clay was combined with each sludge on a mass ration basis to discern metal attenuating effects under a low pH environment. The presence of the clay served to reduce metal leachate rates for two of the three sludge-types tested. However, neither sludge-type exhibited leachate concentrations below federally regulated limits. On a metal by metal basis, lead and copper were attenuated to the highest degree, nickel and zinc the lowest. The presence of clay in copper and lead-dominant sludges may serve to lower extract concentrations for both metals and possibly provide an opportunity to have the sludge(s) declared non-hazardous. Conversely, sludges consisting predominantly of nickel and/or zinc would require disposal in a secure landfill.

Cadmium accumulation, retention and sequestering by protein were measured in two Mycobacterium scrofulaceum strains differing in their susceptibility to that toxic heavy metal cation. Cadmium accumulation was energy-dependent and temperature-sensitive. The tolerant strain had lower K_m and V_max values than did the susceptible strain. Cd⁺² accumulation was antagonized by both Zn⁺² and Mn⁺², which agreed with the observation that both cations protected the strains from Cd⁺² toxicity. Further, Zn⁺² and Mn⁺² did not reduce Cd⁺² accumulation to the same extent in the tolerant strain as in the susceptible strain, suggesting that cadmium resulted in more extensive zinc and manganese starvation in the cadmium-susceptible strain. Cd⁺² was retained to the same extent in both the susceptible and tolerant strains by a Cd⁺²-specific, energy-dependent exchange mechanism. Thus, tolerance was not due to accelerated efflux. Though a cadmium-inducible, soluble protein was discovered only in the tolerant strain, its inability to bind Cd⁺² and exclusive production during the stationary phase of growth argued against its role in cadmium tolerance. / M.S.

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.

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

Concentrações de cádmio (Cd), chumbo (Pb) e mercúrio (Hg) foram determinadas em amostras de água (teores dissolvidos e particulados), sedimento de fundo, peixes e bivalves, coletados em seis bacias hidrográficas do Estado de São Paulo: Alto Paranapanema, Peixe, Aguapeí, São José dos Dourados, Mogi-Guaçu e Piracicaba, as quais apresentam diferentes características quanto ao uso e ocupação da terra. Dentre estas bacias, as dos rios Piracicaba e Mogi-Guaçu apresentam maiores densidades demográficas e industrialização, o que gera, conseqüentemente, maior degradação da qualidade das águas, enfatizando a necessidade de estudos freqüentes nesses sistemas. As amostragens de água e sedimento foram feitas bimestralmente durante o ano de 2001. Os peixes e bivalves foram amostrados no mesmo ano em dois períodos: seca e cheia. As concentrações de Cd e Pb foram determinadas por espectrometria de absorção atômica com atomização eletrotérmica, e as de Hg por espectrometria de fluorescência atômica. Os teores de Cd e Pb na fração trocável do sedimento também foram determinados. Os resultados obtidos mostraram baixas concentrações dos metais Cd e Pb na coluna d’água, tanto nas formas dissolvidas quanto particuladas, no entanto, tais concentrações foram maiores nas bacias dos rios Piracicaba e Mogi-Guaçu. No sedimento de fundo e nos bivalves, as maiores concentrações de Pb foram observadas no rio Mogi-Guaçu, embora este elemento tenha ocorrido em pequenas quantidades na fração trocável do sedimento (<1%). O Cd ocorreu em maiores teores no sedimento e no material particulado do rio Piracicaba. Por outro lado, as maiores concentrações de Pb nos bivalves foram detectadas no rio Mogi-Guaçu. Na fração trocável do sedimento, o Cd ocorreu em altas proporções (até 76%), principalmente, nos rios Itapetininga (Bacia do Alto Paranapanema), Piracicaba e Mogi-Guaçu. Em algumas amostras de água e sedimento de fundo ocorreram quantidades relativamente elevadas de Hg. Por outro lado, nos bivalves os teores do elemento foram sempre baixos. No entanto, nenhuma tendência significativa de distribuição espacial ou temporal de Hg ocorreu nas amostras. Portanto, acredita-se que os altos teores registrados para algumas amostras foram resultantes de fontes de origem difusa não-pontual, como deposição atmosférica e fontes originárias da agricultura. Nos peixes, as concentrações de Cd e Pb foram sempre inferiores aos limites de detecção (0,005 e 0,08 µg/g peso seco, respectivamente). Por outro lado, peixes carnívoros coletados no reservatório de Jurumirim (bacia do Alto Paranapanema) apresentaram altas concentrações de Hg (média: 1,14 +/- 0,54 µg/g peso úmido) e metilmercúrio (média: 1,04 +/- 0,51 µg/g peso úmido). Este último, representou em média 92% do mercúrio total determinado no músculo dos peixes. Tais concentrações foram maiores que o máximo permitido pela legislação brasileira para peixes predadores (1 µg/g peso úmido) e, provavelmente, foram resultante de altos teores de metilmercúrio produzido no reservatório devido aos processos de produção e liberação de mercúrio a partir da vegetação e solos inundados. Portanto, concluiu-se que os peixes do reservatório de Jurumirim estavam contaminados com Hg, recomendando-se que novos estudos sejam realizados para se identificar as fontes e processos responsáveis por tais contaminações. As bacias dos rios do Peixe, Aguapeí, Alto Paranapanema e São José dos Dourados apresentaram baixas quantidades de todos os elementos estudados. Por outro lado, foram observadas concentrações relativamente elevadas de Cd no rio Piracicaba, e Pb e Cd no rio Mogi-Guaçu, os quais devem ser periodicamente avaliados. / Concentrations of cadmium (Cd), lead (Pb), and mercury (Hg) were determined in water (dissolved and particulate), bottom sediment, fish, and bivalves sampled in six watersheds located in the State of São Paulo (Southeast, Brazil): the Alto Paranapanema, the Peixe, the Aguapeí, the São José dos Dourados, the Mogi-Guaçu, and the Piracicaba. These watersheds show different levels of land-use. Among these basins, the Piracicaba and the Mogi-Guaçu River Basins show highest population and industrialization rates. Such features lead, consequently, to a higher degradation of water, thus decreasing its quality. These facts emphasize the need of new and frequent studies in those systems. Water and sediment samplings were carried out bimonthly during 2001. Fish and bivalves samples were collected twice a year: at the end of the rainy and dry season. Cd and Pb concentrations were determined through electrotermal atomic absorption spectrometry, whereas Hg through atomic fluorescence spectrometry. In addition, exchangeable Cd and Pb were determined in sediment. The results showed low concentrations of Cd and Pb in water (dissolved and particulate). However, these concentrations were higher in the Piracicaba and the Mogi-Guaçu River Basins. Pb concentrations in sediment and bivalves were the highest in the Mogi-Guaçu River, even so this element occurred in low levels in the exchangeable fraction of sediment (< 1%). The highest Cd concentrations in sediment and particulate suspended matter were related to the Piracicaba River, although the highest levels for bivalves occurred in the Mogi-Guaçu River. High Cd concentrations in the exchangeable fraction of sediment (up to 76%) were observed, mainly in the Itapetininga (the Alto Paranapanema Basin), the Piracicaba, and the Mogi-Guaçu River. High concentrations of Hg were detected in some water and sediment samples, whereas in bivalves Hg was always in low levels. However, no significant tendency of temporal and/or spatial distribution was observed for Hg, so it is belived that the high levels reported for some samples were a result from diffuse non-point source pollution, such as atmospheric deposition and residues from agricultural practices. Cd and Pb concentrations in fish were always lower than the detection limit (0.005 and 0.08 µg/g dry wt, respectively). On the other hand, high concentrations of Hg (1.14 +/- 0,54 µg/g wet wt) and methylmercury (1.04 +/- 0.51 µg/g wet wt), which represented 92% of the total mercury, were found in carnivorous fish samples from the Jurumirim Reservoir (the Alto Paranapanema Basin). These concentrations were higher than the maximum limit permitted by Brazillian legislation for predatory fish (1 µg/g wet wt) and, probably, were a result from high methylmercury levels produced and released in the reservoir supported by inundated soil and vegetation. Hence, we concluded that carnivorous fish from the Jurumirim Reservoir were contamined with Hg, therefore new research sould be carried out in that area in order to identify the sources and processes responsible for high levels of mercury. The Peixe, the Aguapeí, the Alto Paranapanema, and the São José dos Dourados River Basins showed relatively low concentrations of all elements studied. Conversely, high Cd concentrations were determined in the Piracicaba River, and Pb and Cd in the Mogi-Guaçu River, pointing out that these areas should be frequently monitored.