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Evaluation Of Persistent Organic Pollutants (pops) In Balikesir Dam Lake SedimentsGokmen, Pinar 01 February 2011 (has links) (PDF)
In this study, the Persistent Organic Pollutants (POPs) specifically / 17
Organochlorine Pesticides (OCPs) and 19 Polycyclic Aromatic Hydrocarbons
(PAHs) were evaluated in the sediment samples of Balikesir (Ikizcetepeler) Dam
Lake. Sixteen sampling points were chosen for determination of concentrations of
OCPs and PAHs After ultrasonic bath extraction of the sediment samples GC-MS
was used as analytical tool. Extraction efficiencies changes from 63.8 to 87.4%
depending on the type of the POPs. Average OCP concentration was found in the
range of 3.33-379 µ / g/kg a, average PAH concentration was found in the range of
3.28-32.9 µ / g/kg. Pollution maps regarding OCP and PAH distributions were drawn
and the correlation between these two pollutant types was investigated. The quality
control (QC) and quality assurance tests were applied by the analysis of standard
reference materials (SRMs), surrogate standards and analysis replicates.
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Investigating morphological changes in fish tissue, due to the presence of persistent organic pollutants and metals / W. Pheiffer.Pheiffer, Wihan January 2012 (has links)
Levels of selected metals and persistent organic pollutants (POPs) were investigated in sediment and fillet tissue of the sharptooth catfish (Clarias gariepinus), from sites along the Orange-Vaal River system, South Africa.
A histological assessment was done on the livers, kidneys, and gills of the fish sampled to determine morphological changes. The sediment and fish sampling sites were selected up- and downstream of major pollution sources such as mining, industrial and agriculture. The concentrations of the metals in the fish and sediment was determined with an inductively coupled plasma mass spectrometry and the POPs with a high resolution gas chromatographyhigh resolution mass spectrometer. Indices were calculated to describe the quality of the sediment The enrichment factor (Ef) of individual heavy metals evaluated elevation in levels above natural geology. The geo-accumulation index (Igeo) determined the degree of pollution by the enrichment levels of the individual metals. The pollution effect of the total mixture of the heavy metals was investigated by the metal pollution index (MPI) and pollution load index (PLI). Ecological risk was determined by calculating the sediment quality guideline index (SQG-I) and a sediment quality index (SQI) to determine the quality of the sediment. For the SQG-I and SQI, international sediment quality guidelines were used, since South Africa does not have them. The bio-accumulation factor (BF) was calculated between sediment and fish. A limited human health risk assessment was done for the consumption of Clarias gariepinus. A semi-quantitative histopathological assessment was preformed and alterations found were numerically described with the aid of mean organ indices.
The POPs values were very low. The Igeo and Ef of Se, Hg, Ag and Au were the highest at all the sites. Parys had the most metals that were enriched to different degrees, but Rooipoort had the highest MPI and PLI. The SQG-I indicated that the sites had a moderate chance of posing an ecological risk to its biota, except for Rooipoort that had a high toxic probability. The SQI classified Rooipoort as “fair” in terms of sediment quality and the rest of the sites as “good”. The semi-quantitative histology based assessment results showed that the mean organ and fish indices fell within class 1 (normal tissue structure with slight histological alterations) or class 2 (normal tissue structure with moderate histological alterations). The mean gill, -liver and kidney indices for all the sites fell in class 1. The mean fish index for all the sites however, fell in class 2. The human health risk assesment showed high risk for non-carcinogenic effects from Ag, Hg, As and Cr if fish from the sample sites were to be consumed.
The results from this study identified that the river system is polluted by anthropogenic activities. Results showed that the pollutants of concern in the system were ultimately Ag, Hg and PFOS. Although the morphology of Clarias gariepinus was not altered, the results indicated that the Orange-Vaal River system is polluted and that these fish is unsafe for human consumption. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2013.
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Investigating morphological changes in fish tissue, due to the presence of persistent organic pollutants and metals / W. Pheiffer.Pheiffer, Wihan January 2012 (has links)
Levels of selected metals and persistent organic pollutants (POPs) were investigated in sediment and fillet tissue of the sharptooth catfish (Clarias gariepinus), from sites along the Orange-Vaal River system, South Africa.
A histological assessment was done on the livers, kidneys, and gills of the fish sampled to determine morphological changes. The sediment and fish sampling sites were selected up- and downstream of major pollution sources such as mining, industrial and agriculture. The concentrations of the metals in the fish and sediment was determined with an inductively coupled plasma mass spectrometry and the POPs with a high resolution gas chromatographyhigh resolution mass spectrometer. Indices were calculated to describe the quality of the sediment The enrichment factor (Ef) of individual heavy metals evaluated elevation in levels above natural geology. The geo-accumulation index (Igeo) determined the degree of pollution by the enrichment levels of the individual metals. The pollution effect of the total mixture of the heavy metals was investigated by the metal pollution index (MPI) and pollution load index (PLI). Ecological risk was determined by calculating the sediment quality guideline index (SQG-I) and a sediment quality index (SQI) to determine the quality of the sediment. For the SQG-I and SQI, international sediment quality guidelines were used, since South Africa does not have them. The bio-accumulation factor (BF) was calculated between sediment and fish. A limited human health risk assessment was done for the consumption of Clarias gariepinus. A semi-quantitative histopathological assessment was preformed and alterations found were numerically described with the aid of mean organ indices.
The POPs values were very low. The Igeo and Ef of Se, Hg, Ag and Au were the highest at all the sites. Parys had the most metals that were enriched to different degrees, but Rooipoort had the highest MPI and PLI. The SQG-I indicated that the sites had a moderate chance of posing an ecological risk to its biota, except for Rooipoort that had a high toxic probability. The SQI classified Rooipoort as “fair” in terms of sediment quality and the rest of the sites as “good”. The semi-quantitative histology based assessment results showed that the mean organ and fish indices fell within class 1 (normal tissue structure with slight histological alterations) or class 2 (normal tissue structure with moderate histological alterations). The mean gill, -liver and kidney indices for all the sites fell in class 1. The mean fish index for all the sites however, fell in class 2. The human health risk assesment showed high risk for non-carcinogenic effects from Ag, Hg, As and Cr if fish from the sample sites were to be consumed.
The results from this study identified that the river system is polluted by anthropogenic activities. Results showed that the pollutants of concern in the system were ultimately Ag, Hg and PFOS. Although the morphology of Clarias gariepinus was not altered, the results indicated that the Orange-Vaal River system is polluted and that these fish is unsafe for human consumption. / Thesis (MSc (Environmental Sciences))--North-West University, Potchefstroom Campus, 2013.
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Privatägda offentliga platser - En fallstudie om Emporias takparkLorentzi Wall, Lisa, Lindby, Matilda January 2018 (has links)
Vår undersökning behandlar fenomenet POPS, Privately Owned Public Spaces.Offentliga platser har historiskt sett varit viktiga för en stad på grund av dessdemokratiska och sociala värden. Dessa värden riskerar att försvinna när stadensoffentliga platser privatiseras. Vi har gjort en fallstudie av Emporias takpark där viundersökt hur platsen används och kontrolleras. Analysen visar att privatägda offentligaplatser tenderar att kontrolleras med verktyg som övervakning och regler. Detta leder tillatt vissa grupper i samhället mer eller mindre exkluderas från dessa platser till förmånför en köpstark samhällsgrupp och i förlängningen stadens image. / Our study treats the phenomenon POPS, Privately Owned Public Spaces. Publicplaces have historically been important in cities because of their democratic andsocials values. There is a risk that these values disappear when public places of thecity are privatized. We have done a case study of Emporia rooftop park where weresearched how the space is used and controlled. Our analysis shows that privatelyowned public places tend to be controlled by tools such as surveillance and rules.This leads to certain groups in society getting more or less excluded from these placesin favor of a more well-funded social group and in extension the image of the city.
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Hat die Belastung gestillter Kinder mit persistenten organischen Schadstoffen Einfluss auf natürliche Killerzellen?Husain, Ralf 14 July 2004 (has links)
Gestillte Kinder sind über die Muttermilch mit persistenten organischen Schadstoffen (POPs) belastet. Tierexperimentelle Studien deuten auf eine besondere Empfindlichkeit des sich entwickelnden Immunsystems für POPs hin. Mögliche Effekte dieser Verbindungen auf den kindlichen Organismus sind bisher kaum untersucht. Es wurden potenzielle Einflüsse verschiedener POPs (PCDDs, PCDFs, PCBs, beta-HCH, HCB und pp-DDE) auf natürliche Killerzellen (NK-Zellen) und NK-Aktivität bei gestillten im Vergleich zu nicht gestillten Kindern untersucht. NK-Zellen sind eine Lymphozytensubpopulation (CD3-CD56/16+), die über ihre zytotoxische Aktivität allogene, virusinfizierte und maligne Zellen ohne vorherige Sensibilisierung töten kann. Es wurden 66 gesunde Kinder im Alter von 11-12 Monaten untersucht, davon waren 50 Kinder mindestens 4 Monate lang voll gestillt und 16 Kinder nicht gestillt. Aus einer Region mit bekannter erhöhter PCDD/PCDF-Belastung stammten 13 gestillte Kinder. Die NK-Zellzahlen wurden mittels Immunphänotypisierung am Durchflusszytometer bestimmt. Die Aktivität der NK-Zellen wurde mit einem nicht-radioaktiven, durchflusszytometrischen Zytotoxizitäts-Assay gemessen. Die POP-Konzentrationen im Blutfett der Probanden wurden kommerziell bestimmt. Weder bei den NK-Zellzahlen, noch bei der NK-Aktivität konnten zwischen den gestillten und nicht-gestillten Kindern signifikante Unterschiede im t-Test nachgewiesen werden. In Korrelationsanalysen zeigten sich keine signifikanten Einflüsse der POP-Konzentrationen auf NK-Zellzahlen und NK-Aktivität. Im Laufe der Untersuchung zeigte sich, dass der eingesetzte Zytotoxizitäts-Assay nur semiquantitative Daten lieferte. Die vorliegenden Ergebnisse und weitere Befunde bezüglich des Immunsystems der Probanden weisen darauf hin, dass die relativ hohe Belastung lange gestillter Säuglinge mit POPs nicht zu einer biologischen Wirkung im kindlichen Organismus führt. Angesichts der nachgewiesenen positiven Effekte des Stillens, kann diesbezüglich die bestehende Stillempfehlung bekräftigt werden. / Breast-fed infants are exposed to persistent organic pollutants (POPs) via breast milk. Animal studies indicate a special sensitivity of the maturing immune system to POPs. Possible effects of these compounds on the infantile organism are so far barely examined. Potential influences of several POPs (PCDDs, PCDFs, PCBs, beta-HCH, HCB and pp-DDE) on natural killer (NK) cells and NK activity of breast-fed infants in comparison to formula-fed infants were investigated. NK cells are a subset of lymphocytes (CD3-CD56/16+) that can kill allogeneic, virus-infected and malignant cells via their cytotoxic activity without prior sensitization. The study group consisted of 66 healthy infants examined at age 11 to 12 months, of which 50 infants were breast-fed and 16 infants were formula-fed. 13 breast-fed infants came from a region with known increased PCDD/PCDF-burden. Numbers of NK cells were measured by flow cytometric immunophenotyping. NK activity was analysed by a non-radioactive flow cytometric cytotoxicity assay. POP concentrations in the blood fat of the probands were calculated commercially. There were no significant differences between breast-fed and formula-fed infants concerning number and activity of NK cells in the t-test. Analysis of correlation showed no significant influences of POP concentrations on the number and activity of NK cells. In the course of the study the data obtained by the employed cytotoxicity assay proved to be only semiquantitative. The presented findings and further results concerning the immune system of the study subjects suggest that the relatively high burden of long-term breast-fed infants with POPs does not lead to a biological effect in the infantile organism. Regarding the proven positive effects of breast-feeding the existing recommendation to breastfeed can be encouraged.
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Modélisation mécaniste de la bioaccumulation de contaminants organiques (PCB et PFAS) chez les poissons dans le contexte du changement global : application aux juvéniles de sole commune de l’estuaire de la Gironde. / Modelling mechanistic bioaccumulation of organic contaminants (PCBs and PFASs) in fish in the context of global change : application to the Gironde estuary juvenile common soleMounier, Florence 28 March 2019 (has links)
Les estuaires sont des écosystèmes aquatiques particulièrement soumis au changement global et notamment à la pollution par de nombreux xénobiotiques pouvant présenter un risque écotoxicologique et sanitaire. En toxicologie environnementale et en évaluation des risques la bioaccumulation est un processus fondamental car elle contrôle les doses internes de toxiques potentiels. Or les flux de contamination et de décontamination des organismes dépendent de processus internes (e.g. nutrition, croissance) eux-mêmes dépendant des conditions environnementales (e.g. température, nourriture) qui peuvent être affectées par le changement global.Dans ce contexte, cette thèse se propose de décrire, dans un cadre de modélisation mécaniste, les processus de bioaccumulation de deux familles de polluants organiques persistants (POP) halogénés potentiellement toxiques et bioaccumulables, aux propriétés physico-chimiques contrastées : les polychlorobiphényles (PCB, composés historiques fortement lipophiles) et les substances perfluorées (PFAS, composés émergents amphiphiles). Ce travail se focalise sur l’estuaire de la Gironde dont la fonction de nourricerie est fondamentale pour de nombreuses espèces de poissons marins dont la sole commune (Solea solea), souvent utilisée comme indicatrice de la qualité des nourriceries côtières et estuariennes.Pour permettre de tenir compte des fluctuations des conditions environnementales sur la bioaccumulation, dans la première partie de ce travail, j’ai développé un modèle de toxicocinétique(TK) couplé avec un modèle mécaniste bioénergétique basé sur la théorie DEB (Dynamic Energy Budget). Ce modèle DEB a été paramétré pour la sole commune et calibré pour chaque sexe (package DEB tool). Il permet de prédire les principales évolutions des fonctions physiologiques d’intérêt en bioaccumulation (ingestion, croissance, reproduction...), tout au long du cycle de vie d’un individu, en fonction de conditions environnementales dynamiques. Le modèle TK développé a été complexifié par l’ajout d’un flux d’élimination de contaminants, non considéré dans les précédents modèles DEB-TK.La calibration des paramètres toxicocinétiques (TK) du modèle, pour 4 congénères de PCB, est basée sur une méthode innovante de prise en compte de la variabilité individuelle d’ingestion, appliquée à une expérimentation de contamination de juvéniles de sole via leur nourriture. Ce travail a montré que même en tenant compte de l’ingestion de chaque poisson, l’assimilation efficace de contaminant était très variable et corrélée aux taux de lipides des individus. Dans une seconde partie, ce modèle a été appliqué aux conditions in situ de l’estuaire de la Gironde. Il a permis de mettre en évidence la forte influence de la composition du régime alimentaire sur la variabilité de l’âge à la maturité sexuelle et de la contamination des soles pour les deux familles de contaminant étudiées. La confrontation des prédictions du modèle aux mesures de contaminants dans les juvéniles de sole de l’estuaire a permis de calibrer les paramètres TK du composé majeur de chaque famille dans l’environnement (CB153 et PFOS). Cette calibration a conduit à deux constats dans le cadre de l’évaluation du risque : (1) un manque de connaissances pour extrapoler les calibrations de paramètres TK en conditions contrôlées vers les conditions naturelles ; (2) la différence d’erreur d’évaluation du risque liée à l’utilisation des mêmes paramètres TK «les plus pessimistes » quels que soient les composés. Enfin, des scenarios prospectifs simples ont été développés pour illustrer ces résultats et les possibles applications du modèle développé.In fine, ces prédictions de la contamination, de la croissance et du développement des soles pourront être reliées, lors de travaux ultérieurs, à des effets potentiels sur les fonctions physiologiques de la sole (modèles DEBtox), et aux conséquences sur la dynamique des populations de soles (e.g.modèles matriciels de population). / Estuarine ecosystems are particularly impacted by global change and, specifically, bychemical pollution from numerous xenobiotics that may be associated to ecotoxicological and health risks. In environmental toxicology and risk assessment, bioaccumulation is a fundamental process as it controls the internal doses of potential toxicants in organisms. However, the contamination and decontamination flows depend on internal processes thatare themselves dependent on environmental conditions (e.g. temperature, food) and thus on the other variables of global change.In this context, this manuscript aims at describing, within a mechanistic modelling framework, the bioaccumulation processes of two families of potentially toxic and bioaccumulable halogenated persistent organic pollutants (POPs) with contrasting physicochemical properties: the polychlorinated biphenyls (PCBs, highly lipophilic historical compounds) and the perfluorinated substances (PFAS, amphiphilic emerging compounds).This work focuses on the Gironde estuary whose nursery function is fundamental for many species of marine fish including the common sole (Solea solea), often used as an indicator of the quality of coastal and estuarine bursary grounds. In order to account for the influence of environmental conditions on bioaccumulation, the first part of this work consisted in developing a toxicokinetic model (TK) coupled with a mechanistic bioenergetic model based on the theory DEB (Dynamic Energy Budget). This DEBmodel has been parameterized for common sole and calibrated for each sex (packageDEBtool). It allows predicting the main evolution of the physiological functions of interest forbioaccumulation (ingestion, growth, reproduction...) throughout the life cycle of an individualaccounting for dynamic environmental conditions. The developed TK model was first calibrated for some PCBs, under controlled conditions, using an innovative method to take into account individual ingestion variability. This work showed that even if the individual ingestion of each fish is accounted for, the effective assimilation of contaminant is very variable and correlated with the lipid levels of the individuals. The application of the model tothe in situ conditions of the Gironde estuary led to identify that, whatever the contaminant family, the composition of the soles diet had a strong influence on the variability of soles contamination and age at sexual maturity. The comparison of model predictions with measurements made in juveniles of the estuary allowed calibrating the TK parameters values for the major compound of each family in the environment (CB153 and PFOS). This calibration led to two observations in the context of a risk assessment: (1) a lack of knowledge to extrapolate calibrations of TK parameters under controlled conditions to natural conditions;(2) the difference in risk assessment error related to the use of the same "worst case" TK parameters regardless of the compounds. Lastly, simple prospective scenarios have beendeveloped to illustrate these results and the possible applications of the model developed.Ultimately, these predictions of soles contamination, growth and development may be related in future work to potential effects on the physiological functions of sole (DEBtox models), and to consequences on soles population dynamics (e.g. matrix population models).
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Determination and characterisation of trace metals and persistant oganic pollutants in Baynespruit river, Sobantu, KwaZulu-Natal, South AfricaZuma, Vincent Thulani 06 1900 (has links)
This study assesses the presence of selected trace metals and pops in the Baynespruit River, Sobantu, KwaZulu-Natal. Sediments, plants and water samples were collected along the river during dry and wet season. For metal analysis, the extraction was done using acid digestion and then determined on the inductively coupled plasma atomic emission spectroscopy, for total metals in sediments, plants and water. Bio-available metals in sediments were analysed using atomic absorption spectroscopy. POPs were extracted in sediments using soxhlet extraction, which was followed up by evaporation on the rotary evaporator, sample clean up on a GPC column, further sample concentration on the rotary evaporator and later analysed on GC/MS instrument. Metals of concern in both seasons were Cu, Cr, Pb and Zn which exceeded maximum permissible limits for South African soil, Cr was just about the maximum permissible limit. The targeted POPs were not detected on any site during this work. / Environmental Sciences / M. Sc. (Environmental Science)
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In silico methods to prioritize chemicals with high exposure potentialReppas Chrysovitsinos, Efstathios January 2017 (has links)
Chemicals offer a wide range of desired functions and are used in a variety of consumer goods and industrial sectors. The number of individual synthetic organic chemicals produced and the total global chemical production volume are increasing. The majority of these anthropogenic chemicals are not monitored in environmental matrices nor in the indoor environment even though some are associated with undesirable consequences and the range of possible chemical impacts is still far from being fully understood. Chemicals that remain in the environment for a long time and/or distribute over a large area have high exposure potential, and will present particularly acute challenges if a currently unknown undesirable effect is discovered. This thesis describes the development of a set of in silico methods to identify and prioritize chemicals with high exposure potential that are currently not subject to national or international restrictions. In brief, we i) compiled databases of contaminants of potential concern, ii) established models to predict key properties to fill data gaps in the absence of experimental data, and iii) developed and applied methods to screen chemicals to identify those that should be assigned high priority for future study. Paper I delivers screening-level models to predict partition ratios of organic chemicals between polymeric materials commonly found indoors, and both air and water. These models can be used in high-throughput exposure assessment studies, passive sampling experiments, and models of emissions, fate and transport of chemicals. Paper II presents a scoring method to prioritize 464 organic chemicals of emerging Arctic concern for their potential to fit a set of four exposure-based hazard profiles. These four profiles represent persistent organic pollutants (POPs) regulated under the Stockholm Convention, very persistent and very bioaccumulative substances (vPvBs) regulated under REACH and for two novel and unregulated profiles derived from the planetary boundary threats framework; airborne persistent contaminants (APCs) and waterborne persistent contaminants (WPCs). APCs and WPCs are chemicals that are mobile in air and water, respectively, and that contaminate the environment in a poorly reversible manner due to their persistence. The prioritization method is based on a reference set of 148 chemicals that is used to contextualize the scoring results. Paper III describes the prioritization of 8,648 chemicals that were reportedly produced in five OECD countries. Paper III elucidates the relationship between the elemental composition of these chemicals and the exposure-based hazard scores, and presents a strategy to disentangle overlaps among the four exposure hazard profiles by categorizing chemicals according to the spatial coverage of profiles they best fit. Paper IV focuses on refining the prioritization method described in Papers II and III using a set of 5,600 hypothetical chemicals. The refined method is used to prioritize the chemicals from Papers II and III, and an additional 4,567 chemicals from the REACH database. The in silico methods developed in this thesis can be applied to conduct screening-level exposure assessments using only chemical structures as a starting point. Substances prioritized as having high potential to be POPs, vPvB, APC, or WPC should be considered for more detailed study to unequivocally determine their identity and physicochemical properties. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.</p>
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SMALL ANGLE SCATTERING OF LARGE PROTEIN UNITS UNDER OSMOTIC STRESSLuis Palacio (8775689) 30 April 2020 (has links)
<div>Large protein molecules are abundant in biological cells but are very difficult to study in physiological conditions due to molecular disorder. For large proteins, most structural information is obtained in crystalline states which can be achieved in certain conditions at very low temperature. X-ray and neutron crystallography methods can then be used for determination of crystalline structures at atomic level. However, in solution at room or physiological temperatures such highly resolved descriptions cannot be obtained except in very few cases. Scattering methods that can be used to study this type of structures at room temperature include small-angle x-ray and neutron scattering. These methods are used here to study two distinct proteins that are both classified as glycoproteins, which are a large class of proteins with diverse biological functions. In this study, two specific plasma glycoproteins were used: Fibrinogen (340 kDa) and Alpha 1-Antitrypsin or A1AT (52 kDa). These proteins have been chosen based on the fact that they have a propensity to form very large molecular aggregates due to their tendency to polymerize. One goal of this project is to show that for such complex structures, a combination of scattering methods that include SAXS, SANS, and DLS can address important structural and interaction questions despite the fact that atomic resolution cannot be obtained as in crystallography. A1AT protein has been shown to have protective roles of lung cells against emphysema, while fibrinogen is a major factor in the blood clotting process. A systematic approach to study these proteins interactions with lipid membranes and other proteins, using contrast-matching small-angle neutron scattering (SANS), small angle x-ray scattering (SAXS) and dynamic light scattering (DLS), is presented here. A series of structural reference points for each protein in solution were determined by performing measurements under osmotic stress controlled by the addition of polyethylene glycol-1,500 MW (PEG 1500) in the samples. Osmotic pressure changes the free energy of the molecular mixture and has consequences on the structure and the interaction of molecular aggregates. In particular, the measured radius of gyration (Rg) for A1AT shows a sharp structural transition when the concentration of PEG 1500 is between 33 wt\% and 36 wt\%. Similarly, a significant structural change was observed for fibrinogen when the concentration of PEG 1500 was above 40 wt\%. This analysis is applied to a study of A1AT interacting with lipid membranes and to a study of fibrinogen polymerization in the presence of the enzyme thrombin, which catalyzes the formation of blood clots. The experimental approach presented here and the applications to specific questions show that an appropriate combination of scattering methods can produce useful information on the behavior and the interactions of large protein systems in physiological conditions despite the lower resolution compared to crystallography.</div>
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Analysis of Heavy Metals and Persistent Organic Pollutants in Sewage Sludge from Thohoyandou Wastewater Treatment Plant and transfer to Vegetables.Akinsaya, Nurudeen Akinwale 18 May 2018 (has links)
MENVSC / Department of Hydrology and Water Resources / Sewage sludge (biosolids) from wastewater treatment plants (WWTPs) has been widely used
as a soil improver in Europe, United States of America and some developing countries
including South Africa. It has its benefits for farmers as a good source of organic matter and
minerals, however, sludge after treatment still contains pathogenic organisms, heavy metals
and persistent organic pollutants (POPs). The POP and heavy metal contaminants that
accumulate in sludge may transfer through the food chain and cause adverse effects on
human beings.
In this study, a field experiment was carried out on farmland fertilized with sewage sludge
from a wastewater treatment plant (WWTP) that vasically receives domestic wastewater and
storm water. Vegetable spinach (Spinacia oleracea) was used for this study and was planted
on a farmland under controlled conditions. Ten ridges each of dimensions 20 m × 0.3 m was
made and dry sludge weights of 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50 kg were applied as
manure on each of the ridges, respectively.
Representative samples of sludge and soil were taken for analysis of heavy metals and POPs.
At maturity, in twelve weeks, the root and leave samples of the vegetable were taken from all
the ridges including the control. The soil, sludge, and vegetable samples were analyzed for
total heavy metal content (Cd, Cr, Cu, Ni, Pb, Co, Zn, Al, Fe, Mn), speciated heavy metal
content and POP (PAH, PCB). Soil and sludge samples were also analyzed for total organic
content, pH, cation exchange capacity (CEC), conductivity and alkalinity. The analysis for
total heavy metals and speciated heavy metal content was carried out using inductively
coupled plasma optical emission spectrophotometer (ICP-OES), and CEC analysis was
carried out using atomic absorption spectrophotometer (AAS). A two-dimensional gas
chromatograph with time of flight mass spectrometry detector (GC X GC TOFMS) was used
for POP measurements. pH measurement was made using a pH meter and conductivity
measurement using a conductivity meter. Alkalinity and total organic content analysis was
performed using titrimetric apparatus. The highest total heavy metal concentration of 378.9
mg / kg was recorded in Fe metal in soil and Leaf sample while the lowest total metal
concentration of 0.0003 mg / kg was in Cu metal in root sample. The highest heavy metal
concentration of 1002 mg / kg in speciated forms was in Mn metal in F1 fraction and the
lowest of 0.0004 mg / kg was in Cd metal in F5 fraction. PAHs were only found in soil
samples and their concentrations ranged from 2.53 mg / kg to 146.5 mg / kg. There were no
PCB detected in all the samples analysed. The results indicated that the trace metals
concentrations found in the exchangeable fraction were higher than those observed in any of
the preceding extractions except in the case of Cd, Cr, Fe and Pb where Fe-Mn oxide and
organic matter fractions predominated and were closely followed by exchangeable fraction.
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