Measuring the concentration of particles in water is important in many areas. Industries might measure it to run more efficiently while scientists might measure it to study the pollution of a body of water. Regardless of the area, the standard for taking a measurement is done by filtering out the particles by hand. This is a very slow and expensive method, so other alternative methods have been developed. However, all the alternative methods can only estimate the concentration. Therefore, Deepoid AB aims to investigate if ultrasound can be used to measure the concentration of particles in water.\parThis thesis shows that a direct ultrasound signal can be used to measure changes in the concentration of particles in water. It also shows how this method is much faster than measuring the concentration of particles in water by hand.

The purpose of this paper is to study the application of HACCP principles in dairy production systems for mitigation of potential water related hazards by control measures and legislation applicable at farm level. HACCP logical sequence approach including some principles of environmental risk assessment was the method used for the present study (FAO/IDF, 2004;Horchner et al., 2006). Literature review, farms visits, interviews, informal questionnaires and confirmation on site of the gathered information were the prerequisites of the study. Four flow diagrams in SA and three in Benin were drawn to describe the 11 steps relating the activities of the seven types of dairy farming systems recorded altogether in these countries (FAO/IDF, 2004,McCrindle, 2007). From the flow diagrams, almost three groups of 30 potential hazards were identified. Biological, chemical and physical hazards were characterized and their effects described according to the source, pathways, mechanisms, of water pollution. It was noticed that water use during farming activities is linked to the number of animals and is an important factor to qualify the magnitude of the risk of water pollution. Critical Control Points (CCPs) were identified. In SA, national legislation includes legal prerequisites for commercial dairy farming systems (SA GOVERNMENT 2005, 2006, 2007). Although water resources policies, strategies, legislation and management are strongly established, their implementation does not clearly include dairy by-products. In Benin dairy production strategy and development started in 2000. Basic legislation relating water resources is being updated. In commercial farming systems (F1 and F2 in SA), F7 in Benin, biological and chemical potential hazards are the main threat to water quality. Direct or indirect source of contamination due to manure, feces, urine, chemicals and stock remedies, waste water, occurs through husbandry practices (milking), pasture and housing. In SA, farmers are aware of International dairy standards, norms and practices such as GAP, GMP and GHP even if the practices are not completely respected. HACCP is not well yet well implemented at producer level althougth some commercial dairy processors have started the implementation of the system (FEDICS, 2004, CEBENOR, 2007). Environmental care (CCP11 and CCP12) are the main critical control points recorded which are not mitigated by the national legislation in both countries. In regard to traditional farming systems (F3, F4) and in SA, (F5, F6) in Benin, national legislation does not include prerequisites for biological and physical hazards; these are the main threat of water pollution and are due to direct or indirect contamination through drinking and grazing. Chemical hazards are not important because inputs of stock remedies are low in these systems. Farmers are not aware of International dairy standards, norms and practices such as GAP, GMP and GHP which are fairly respected. HACCP is unknown at producer level. CCPs relating animal treatment and care are partly mitigated by the national legislation. Stock remedies, drugs residues and Pharmaceuticals are controlled in both countries although Benin faces the introduction of uncontrolled veterinary drugs through illegal frontiers. The majority of the CCPs are not completely mitigated by national legislation for traditional dairy farms in both countries. / Dissertation (MSc)--University of Pretoria, 2007. / Paraclinical Sciences / unrestricted

>Magister Scientiae - MSc / Recently researchers reported that nanoparticles functionalised through chemical methods possess risks to the environment and to the human health since they use hazardous chemicals and produce toxic waste. The increasing demand of nanomaterials for application in the field of science require an alternative method for synthesis of nanomaterials that are environmentally friendly, eco-friendly and non-toxic. The present study describes the green synthesis method for functionalisation of nanomaterials. Green synthesis methods are considered as a novel approach for functionalisation of nanoparticles using biological sources. / 2022

In recent years, the studies of emerging contaminants have received growing concerns due to their ambiguous fate and unclear effect to the water environment, aquatic organisms or even human. With the development of the analytical techniques, the increase detection rate of emerging contaminants is at a rapid pace that many of their fates and influence are still pending investigation. In this work, a group of organic UV filters, which is one of the vital categories of emerging contaminants are monitored. Organic UV filters, used as the major components in not only sunscreens but also other cosmetics products, have a widespread usage and large production volume for more than 80 years, causing the massive input towards the aquatic environment. To first investigate their environmental behaviours and impacts, the regional distribution of total nine commonly used organic UV filters was monitored along the southeast coastline of Shenzhen, which is the most rapid developing city in China with large population with the consideration of seasonal variation. In addition, the Shenzhen reservoirs, as the major sources of drinking water in Shenzhen, was also monitored together with the city tap water. The results indicated the extensive distribution of certain kinds of UV filters with obvious seasonal pattern, which may cause medium to high risk to aquatic organisms. And the incomplete removal of them in drinking water supply system resulting trace amount of UV filters to be detected in city tap water, may cause a general exposure of these UV filters towards all populations. Therefore, a quantitative analytical method for simultaneous detecting multiple classes UV filters in human urine samples has been developed and applied on more than 100 real samples for determining internal exposure. Similar UV filters were also detected in human urine samples compared with surface water while one of the most commonly used organic UV filters, Ethylhexyl methoxycinnamate exhibited much lower detection rate and concentration in human urine. Then, biotransformation of Ethylhexyl methoxycinnamate was examined in rats for the purpose of selecting suitable metabolites as exposure biomarkers. Several metabolites have been identified in urine and plasma by UHPLC-QTOF-MS. Two of its metabolites, 4-methoxycinnamic acid and 4' -methoxyacetophenone, were unambiguously identified by comparing with commercial standard. Excretion trend of Ethylhexyl methoxycinnamate and its two metabolites confirmed that most of the parent compound were quickly metabolized and excreted through urine samples. Herein, these three targeted compounds were further evaluated in two populations - female university students and school-aged children. Although Ethylhexyl methoxycinnamate was not detected in 49 female university students, significant internal correlations were discovered among these three analytes in school-aged students and extensive detection of metabolites instead of parent compound was also confirmed. The third part of this thesis is to comprehensively monitor the internal exposure of UV filters and their metabolites, and also discover their potential adverse health impacts - obesity in Shanghai children and adolescents. Urinary concentration of certain kinds of UV filters were significantly higher in girls than in boys. However, further associations have been found with urinary Ethylhexyl methoxycinnamate concentration and reduced adiposity outcomes only in boys, indicating it may have the potential to influence the metabolism in male population during growing stage. In short, a complete study of organic UV filters is presented in this thesis, from their environmental occurrence to metabolism in animal models, and finally to human exposure and potential health impacts. The widespread exposure and significant associations with adiposity outcomes can form a solid base for future comprehensive risk assessment of UV filters towards human health

Organochlorines are ubiquitous pollutants of the marine environment. These lipid-soluble and highly persistent compounds are found in detectable amounts in almost all marine organisms, and accumulate in the lipid tissues of marine animals. This bioaccumulation leads to biomagnification of these contaminants in higher trophic levels. Near the top of many marine food chains are found the marine mammals, in whose blubber high levels of organochlorine residues have been measured. The most commonly occurring of these pollutants in these animals are the polychlorinated biphenyls (PCB's) and p,p-DDE, a metabolite of the insecticide DDT. These substances have been shown to cause disruptions in the endocrine, immune, and reproductive systems, and are passed from mother to offspring through the placenta and by lactation. Presence and levels of residues of these compounds are, therefore, monitored in marine mammals to provide an indication of the health of a given population and the environment in which they live. Such monitoring is generally done with the use of gas chromatography (GC). High performance liquid chromatography (HPLC) is little used due to the poor ultraviolet (UV) absorbance properties of many of the organochlorines. PCB's and p,p-DDE do absorb UV well enough at concentrations usually encountered in marine mammals to permit the use of HPLC for detection and semiquantification of these substances. A method was developed for the screening of blubber of marine mammals for total PCB's and p,p-DDE using HPLC. The method was applied to the detection and approximation of levels of these two organochlorines in marine mammals from the east and west coasts of the United States. Geographical differences in levels of the two pollutants were found, indicating differences in primary feeding ranges. Evidence of placental transfer of these two organochlorines was also found. Especially high residue levels were found in the blubber of stranded killer whales, indicating that acquisition of high pollutant burdens is still a problem in these top predators. It was concluded that HPLC can be used to screen marine mammals for PCB's and p,p-DDE, and that residue levels determined can be useful in investigating species range, pollutant burdens, and health of populations.

Groundwater contamination and soil salinisation are a major environmental problem worldwide. Living organisms depend largely on groundwater for their survival and its pollution is of course of major concern. It therefore goes without saying that remedial processes and understanding of the mathematical models that describe contaminant transport is of great importance. The theory of contaminant transport requires understanding of the water ow even at the microscopic level. In this study we focus on macroscopic deterministic models based on di erential equations. Here contaminant will refer to nonreactive contaminant. We aim to calculate Lie point symmetries of the one-dimensional Advection-di usion equation (ADE) for various forms of the di usion coe cient and transport velocity. We aim to employ classical Lie symmetry techniques. Furthermore, reductions will be carried out using the elements of the optimal systems. In concluding, the ADE is analyzed for selected forms of the the di usion coe cient and transport velocity via the potential symmetry method. For the potential symmetries obtained, we investigate the associated invariant solutions.

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