Bibliography: pages 134-147. / Pollution control regulations directed at the land-based factories of the Southern African fish processing industry do not appear to promote the required level of investment in pollution control systems. Two self-administered mail-questionnaires comprising undisguised fixed-alternative and open-ended questions were constructed to survey the opinions and viewpoints of a census consisting of twenty-seven senior managers responsible for making pollution control investments in the demersal and pelagic sectors of the fish processing industry. The first questionnaire was directed at establishing the relative importance of factors that influence waste and pollution control investment decisions as well as the perceptions and preferences of managers with regard to various pollution control policy options. Descriptive statistics such as the modal class were used to summarize the distribution of opinions and viewpoints within the research population. Rank ordered preference data was analyzed using a multidimensional unfolding computer algorithm. This structural multivariate statistical method is a special case of non-metric multidimensional scaling that generates perceptual maps which can aid in the discovery of the hidden structure underlying multidimensional decisions. Investments in waste and pollution control do not appear to have a high priority when compared to other strategic investments that the fish processing industry managers may make. The relative importance of factors that could influence the managers of the industry to invest in waste control equipment appear to be determined by the perceived financial returns that can be expected from such investments. Findings suggest that pollution control legislation is rendered ineffective due to inadequate enforcement. However, it appears that existing legislation needs to be rationalized in order to facilitate compliance. The most favoured pollution control instruments were those that lowered the cost of legally mandated expenses such as subsidies and income tax allowances. These were followed by permit systems which specified the allowable characteristics of discharges while allowing individual companies freedom of choice as to the method of achieving compliance. The second questionnaire was used to verify the researcher's interpretation of the findings and preliminary conclusions drawn from the replies to the first questionnaire.

Wetlands are considered a last line of defence against poor water quality. Despite the natural capabilities of wetlands to remove a variety of contaminants from surface water, the track record for wetland conservation leaves much to be desired. In the northern parts of the City of Tshwane, 84% of wetlands have been degraded. When viewed against the poor bacteriological quality of river water in the study area, the lack of wetland conservation efforts is of particular concern. Given the large number of wetlands in the Tshwane area in need of rehabilitation, this study aimed to devise a methodology to prioritise these wetlands for rehabilitation. No blueprint for such a prioritisation process exists, as studies are adapted to take into account the availability of data and the unique requirements of the study area. The methodology for this study is based on the prioritisation of a specific river basin, based on expected maximum faecal bacterial load originating from various sources of pollution. Four river basins were compared with each other in a series of screening processes. Screening was done on a landscape level using a Geographic Information System (GIS) to generate various composite layers as part of the screening process. The screening processes relied on the application of several weighted criteria. Weights for criteria are based on scientific literature. Weights are also allocated in line with the “worst case scenario”, as the study is in essence an assessment of the various pollution sources and their maximum possible contribution to deteriorating surface water quality. A Simple Additive Weighting technique was used to assess the total pollution loads and total numbers of users at risk from contaminated surface water in each of the river basins. It is important to note that the objective is to only rate the pollution sources, whilst exact pollution loads were not calculated. Diffuse, areal and point sources of pollution were rated using the estimated contributions to faecal coliform loads. The river basin with the highest score was selected for the selection of candidate wetlands for rehabilitation purposes. The Apies River Basin scored highest for most of the criteria, with the exception of the number of households at risk from contaminated surface water. Despite the 0.60 weight allocated to households at risk, the extent of pollution sources in this river basin allowed it to be singled out as the basin in which a wetland for rehabilitation is most urgent in order to attenuate bacterial load. Two wetlands were short listed, based on their high need for rehabilitation, their hydrogeomorphic location (valley bottom with a channel), and given that they are larger than 1ha in size and within a minimum distance from the households at risk. Site level assessments are required for a final selection between the two, taking into account the nature of the current disturbances, the possibility of risk due to back-flooding, the projected costs associated with rehabilitation, the nature of the vegetation associated with the wetlands and the general conservation value of each of the wetlands.

In situ chemical oxidation (ISCO) using permanganate has been increasingly applied to deplete mass from dense nonaqueous-phase liquid (DNAPL) source zones. However, uncertainty in the performance of ISCO on DNAPL contaminants is partially attributable to a limited understanding of interactions between the oxidant, subsurface hydrology, and DNAPL mass transfer, resulting in failure to optimize ISCO applications. To investigate these interactions, a factorial design experiment was conducted using one-dimensional flow through tube reactors to determine how groundwater velocity, permanganate concentration, and DNAPL type affected DNAPL mass depletion rates. DNAPL mass depletion rates were found to increase with increasing groundwater velocity, or increasing oxidant concentration. An interaction occurred between the two factors, where high oxidant concentrations had little impact on mass depletion rates at high velocities. High oxidant concentration systems experienced gas generation. Mass depletion rates were fastest at high velocities, but required additional oxidant mass and pore volume addition to achieve complete mass depletion. Lower-velocity systems were more efficient with respect to oxidant mass and pore volume requirements, but mass depletion rates were reduced.

This paper describes laboratory studies conducted to evaluate the impact of varying environmental conditions (dense non-aqueous phase liquid (DNAPL) type and mass, and properties of the subsurface porous media) and design features (oxidant type and load) on the effectiveness and efficiency of in situ chemical oxidation (ISCO) for destruction of DNAPL contaminants. Porous media in 160 mL zero-headspace reactors were employed to examine the destruction of trichloroethylene and perchloroethylene by the oxidants potassium permanganate and catalyzed hydrogen peroxide. Measures of oxidation effectiveness and efficiency include (1) media demand (mg-oxidant/kg-porous media), (2) oxidant demand (mol-oxidant/mol-DNAPL), (3) reaction rate constants for oxidant and DNAPL depletion (min-1), (4) the percent (%) DNAPL destroyed, and (5) the relative treatment efficiency, i.e., the rate of oxidant depletion versus rate of DNAPL destruction. While an obvious goal of ISCO for DNAPL treatment is high effectiveness (i.e., extensive contaminant destruction), it is also important to focus on oxidation efficiency, or to what extent the oxidant is utilized for contaminant destruction instead of competing side reactions, for improved cost effectiveness and/or treatment times. Results indicate that DNAPL contaminants can be treated both effectively and efficiently under many environmental and design conditions. In some cases, DNAPL treatment was more effective and efficient than dissolved/sorbed phase treatment. In these experiments, permanganate was a more effective oxidant, however catalyzed hydrogen peroxide treated contaminants more efficiently (e.g., less oxidant required per mass contaminant treated). Results also indicate that oxidation treatment goals can be dictated by environmental conditions, and that specific treatment goals can dictate remediation design parameters (e.g., faster contaminant destruction was realized in catalyzed hydrogen peroxide systems, whereas greater contaminant destruction occurred in permanganate systems). Journal of Environmental Engineering

Background: Environmental exposure to inorganic arsenic (InAs) is a considerable worldwide problem, and over 57 million people in Bangladesh have been chronically exposed to arsenic-contaminated drinking water. Ingested inorganic arsenic (InAs) undergoes hepatic methylation generating monomethyl- (MMAs) and dimethyl- (DMAs) arsenic species in a process that facilitates urinary As (uAs) elimination. Of these three metabolites (InAs, MMA and DMA), MMA the most toxic, InAs is the second most toxic, and DMA is the least toxic. Consequently, increased MMAs is associated with increased risk of As-related adverse health outcomes. One-carbon metabolism (OCM), the biochemical pathway that provides methyl groups for As methylation, is influenced by folate and B12. A growing body of research, including cell-culture, animal-model, and epidemiological studies, have demonstrated the role of OCM-related micronutrients in As methylation. While folate supplementation is known to increase As methylation and lowers blood As (bAs) in adults, little data is available for adolescents. OCM also supports nucleotide and amino acid synthesis, particularly during periods of rapid growth, such as adolescence. In Bangladesh, deficiencies in folate and vitamin B12 are widespread. These micronutrients are essential for OCM and As methylation, and they are also critical for neural development, since they are necessary for the synthesis of neurotransmitters and myelin, and critical for generation of S-adenosyl-methionine (SAM) via OCM. Deficiencies in folate and B12 have been shown to negatively influence cognitive function in adults and children, but this has not been adequately characterized in adolescents. Individuals living in Bangladesh, facing As exposure and nutritional deficiency, also experience environmental exposure to elevated levels of cadmium (Cd), manganese (Mn), and lead (Pb). These metals have been linked to adverse neurocognitive outcomes in adults and children, though their effects on adolescents are not yet fully characterized. Additionally, previous studies have linked selenium (Se) levels to protective effects against toxicity of these other metals, as Se is an essential nutrient. Metal mixtures are also understudied in adolescents, and more research is needed. Objectives: Firstly, the research presented in this dissertation will examine the previously published evidence that nutritional status and nutritional interventions can influence the metabolism and toxicity of As, with a primary focus on folate. Secondly, the associations between OCM-related micronutrients and As methylation in Bangladeshi adolescents chronically exposed to As-contaminated drinking water will be studied. Thirdly, this dissertation will investigate the associations between folate and B12 nutritional status, homocysteine, and cognitive function as measured by two different test instruments in Bangladeshi adolescents. Finally, the associations between mixed metals exposure and cognitive function in Bangladeshi adolescents will be examined. Methods: The Metals, Arsenic, & Nutrition in Adolescents study (MANAs) is a cross-sectional study of 738 Bangladeshi adolescents aged 14-16 years, whose parents were enrolled in our group’s previous Health Effects of Arsenic Longitudinal Study (HEALS). Venous blood samples were collected from adolescent participants for measurement of plasma folate, red blood cell (RBC) folate, plasma B12, plasma homocysteine (Hcys), blood As (bAs), blood cadmium (bCd), blood manganese (bMn), blood lead (bPb), and blood selenium (bSe). Urine samples were collected for measurement of urinary arsenic and urinary arsenic metabolites (InAs, MMA, and DMA) expressed as a percentage of total urinary As: %InAs, %MMAs, %DMAs. Additionally, participants completed a modified version of the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) and an abbreviated version of the Cambridge Neuropsychological Test Automated Battery (CANTAB). Associations between predictors and outcomes were assessed using linear regression analyses. Associations for the mixture of metals were also examined via Bayesian Kernel Machine Regression (BKMR), which assessed the effects of the metals mixture in addition to examining the effects each individual metal component. Results: In the linear regression analyses examining associations between nutritional status and arsenic methylation profiles controlling for water As and BMI, in girls we observed that RBC folate was inversely associated with bAs, plasma B12 was inversely associated with uAs, and, somewhat unexpectedly, plasma Hcys was inversely associated with %MMA. Among boys, we saw that plasma folate was inversely associated with %InAs and positively associated with %DMA, RBC folate was inversely associated with %InAs and positively associated with %MMA, while Hcys was positively associated with %InAs. In linear regression analyses examining the associations between nutritional status and cognitive function controlling for covariates, we found no significant associations between nutritional status and cognitive function as measured by WISC. For cognitive function as measured by CANTAB, we observed positive associations between plasma folate and spatial recognition memory, and between plasma B12 and spatial working memory. In our investigation of the associations between metal exposures and cognitive outcomes, linear regression analysis revealed negative associations between exposure to As and Mn and spatial working memory. Negative associations were also seen between bCd and Spatial Recognition Memory, and between bPb and Delayed Match to Sample. Finally, a positive association was seen between bSe and Spatial Span Length. Our BKMR results showed no overall effect of the mixture but further characterized the associations for individual metals within the mixture. BKMR analyses indicate that bPb has a negative association to Delayed Match to Sample, and that there are positive associations between bSe and Planning, Reaction Time, and Spatial Span. BKMR also showed higher concentrations of bCd to be negatively associated with Spatial Recognition Memory. Posterior inclusion probability consistently rated Se, which has a protective effect, as the most influential component of the mixture. Conclusions: These findings suggest that associations between OCM nutritional status, blood arsenic, and distribution of urinary As metabolites in adolescents are similar to previously reported observations in adults and in children. The inverse association between Hcys and %MMA in girls is unexpected since Hcys is known to be an indicator of impaired OCM and low folate/B12 in adults. These findings also suggest that associations between nutritional status and cognitive function in adolescents are consistent with previously reported associations in adults and children. The observation of positive associations between folate and spatial recognition memory and between B12 and spatial working memory are consistent with findings in animal models, children, and adults, all of which link deficiencies in these two micronutrients to memory deficits. The findings of the metals investigation are also consistent with previously reported observations in adults and children, and these results also suggest agreement between linear regression and BKMR analysis of the mixed metal exposure, with the BKMR further demonstrating associations seen in the linear regression analysis. Generally, Se had a protective effect for cognitive outcomes, whereas Mn and As were linked to poorer working memory, and Cd and Pb were linked to poorer visual recognition and memory. BKMR reinforced and further characterized results of the linear regression analyses. Overall, these results indicate that the associations between OCM-related micronutrients, arsenic methylation, metal exposure, and cognitive function in adolescents are generally similar to prior findings in adults and children. However, additional studies are needed to evaluate the impact of OCM and As methylation on As-related adverse health outcomes (such as cancer and cardiovascular disease) in people exposed to As during adolescence. These results also suggest that further investigation into the associations between nutritional status and measures of cognitive function in adolescents is merited, and that further exploration of homocysteine’s role in adolescent physiology is needed. Most importantly, these findings suggest that both nutritional interventions involving B12 and folate supplementation and metal exposure mitigation efforts may have a positive impact on overall health and well-being for individuals facing these environmental exposures. In the long term, interventions to reduce exposure to metals and nutritional deficiency, and interventions to attenuate the effects of these exposures have the potential to influence lifelong cognitive function, possibly influencing professional achievement and economic outcomes in regions having a high prevalence of nutritional deficiencies, arsenic exposure, and environmental exposure to metals mixtures.

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2012. / Polychlorinated biphenyls (PCBs) are known harmful chemicals which require urgent remediation, monitoring and assessment in the environment. The predominant current methods used to analyze PCBs involve expertise and are cost intensive. Most of these methods are chromatographic based techniques which are difficult to sustain in Africa due to the expensive nature of the instrument, costly running expenses and skilled labour required. These limitations face Africans, who are the most affected by the presence of PCBs in their environment as a result of improper disposal and usage of these compounds.

Après l'agriculture, l'industrie textile a engendré un important problème de pollution de l'eau car la plupart des produits chimiques provenant de ces industries sont hautement toxiques et affectent directement ou indirectement la santé humaine. La pollution électromagnétique (EM) est un autre problème important qui détériore les performances et la durée de vie des objets électroniques et nuit également à la santé humaine. Dans ce contexte, la nature fibreuse inhérente des nanomatériaux cellulosiques et leurs propriétés mécaniques remarquables, associées à une biocompatibilité et à une ressource durable, offrent un potentiel énorme en tant que composant dans les membranes de filtration de l'eau et les atténuateurs de micro-ondes verts. L'objectif principal de cette thèse est de fabriquer des objets fonctionnels à base de nanofibres de cellulose pour la filtration de l'eau et la suppression des micro-ondes. La méthode présentée dans ce manuscrit décrit un nouveau matériau absorbant à partir de nanofibres de cellulose par l'intermédiaire d'une méthode non solvatée utilisant l'acide de Meldrum comme agent d'estérification pour l'absorption de colorants toxiques. Cette innovation offre une nouvelle plate-forme pour le traitement de surface des nanofibres de cellulose utilisant une technologie verte sans solvant. Classiquement, les métaux ont été utilisés pour protéger les ondes électromagnétiques, mais sont fortement indésirables en raison de leurs inconvénients tels que des poids plus élevés, une nature corrosive et une difficulté de traitement en formes complexes. Les nano- papiers, à base de cellulose conductrice, peuvent offrir une solution verte à ce problème. La cellulose rendue conductrice présente une efficacité de blindage totale de plus de 20 B. Il s’agit d’une plate-forme efficace pour développer des atténuateurs verts respectueux de l'environnement. / After agriculture, the textile dyeing and finishing industry has generated a large water pollution problem as most of the chemicals coming from these industries are highly toxic and directly or indirectly affect human health. Another important issue is the Electro Magnetic (EM) pollution which deteriorates the performance and life of electronic gadgets and also adversely affects the human health. In this context, cellulose nanomaterial’s inherent fibrous nature and remarkable mechanical properties combined with low cost, biocompatibility and sustainable source, suggest huge potential as a component in water filtration membranes and green microwave attenuators in future. The main objective of this thesis is to fabricate cellulose nanofibers based functional constructs for clean water and microwave suppression. The presented unique method to produce novel absorbent material from cellulose nanofibers via non-solvent assisted method using Meldrum’s acid as an esterification agent for absorption of toxic dyes from water has not been addressed till date. This finding offers a new platform for the surface treatment of cellulose nanofibers using solvent free green technology. Conventionally, metals were used to shield EM waves but are highly undesirable due to their inherent drawbacks such as higher weights, corrosive nature and difficulty of processing into intricate shapes. Conductive cellulose nanopapers can offer a potential green feasible solution to this problem. The presented conductive cellulose nanopapers with an effective total shielding effectiveness of > 20 B will be a promising candidate for commercial device applications and will be an effective platform for developing eco-friendly green based attenuators.

Several species of the diatom genus Thalassiosira Cleve, were observed in freshwater phytoplankton samples collected from a fifty-two kilometer reach of the San Joaquin River in the vicinity of Stockton, California, USA. The study was conducted between the South Airport Way bridge near Vernalis and the Stockton Deep Water Ship Channel during fall and summer of both 2005 and 2006. The entire reach is freshwater habitat with the lower twenty-eight km strongly influenced by tidal flow reversals driven by the San Francisco Estuary. Ninety four whole water samples were collected from surface waters during the months of July, August, September and October in 2005 and the months of July and August in 2006. Six species of Thalassiosira were identified using scanning electron and light microscopy: T. weissjlogii (Grunow), T. gessneri Hustedt, T. lacustris (Grunow), T. visurgis (Grunow), T. decipiens (Grunow), and T. incerta (Makarova). Of the species observed, only T. weissjlogii has been previously reported in the freshwater portion of the San Joaquin River. The other five species have been previously reported from sites in the San Joaquin- San Francisco Estuary characterized as brackish, suggesting they are distributed in waters of various salinities ranging from freshwater to brackish within the river and estuary.

No description available.

No description available.