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Submitted by Nara Lays Domingues Viana Oliveira (naradv) on 2015-08-05T19:25:05Z No. of bitstreams: 1 RosangelaBerschEngCivil.pdf: 4573683 bytes, checksum: bcd59ec2871283c130461a507acc1ace (MD5) / Made available in DSpace on 2015-08-05T19:25:05Z (GMT). No. of bitstreams: 1 RosangelaBerschEngCivil.pdf: 4573683 bytes, checksum: bcd59ec2871283c130461a507acc1ace (MD5) Previous issue date: 2011-03-03 / PROSUP - Programa de Suporte à Pós-Gradução de Instituições de Ensino Particulares / A cristalização de sais é uma patologia importante e freqüentemente observada em alvenarias. No entanto é ainda uma das patologias menos compreendidas. O objetivo deste trabalho é justamente avaliar o impacto da florescência de sais solúveis em corpos-de-prova cerâmicos desenvolvidos com lodo de fosfatização. Para tanto, foram moldados corpos-de-prova com 0; 2,5% e 5% (em peso) de lodo, os quais foram sinterizados a temperatura de 750ºC, 850ºC, 950ºC e 1050ºC. Os corpos-de-prova foram divididos em dois grupos, dos quais um foi mantido sob temperatura e umidade controladas e o outro, submetido a ciclos de molhagem e secagem. Os grupos foram ensaiados em 1, 30, 110 e 180 dias. Foram submetidos à análise de imagem (através de Lupa binocular, software gráfico e microscopia eletrônica de varredura), absorção de água por capilaridade, porosimetria por intrusão de mercúrio e resistência à flexão. Para análise química e das fases presentes, foram realizadas análises via difração de raios-x, fluorescência de raios-x e espectrometria de emissão atômica. Os resultados indicam a presença de alumínio, silício, cálcio, potássio, enxofre, ferro e manganês, dos quais se destaca a combinação entre o enxofre e cálcio. Desta forma, a gipsita é tida como provável responsável pelos sais solúveis, cujos depósitos foram encontrados sob variada extensão e intensidade, predominado nos corposde-prova com adição de lodo. A variação da porosidade e a aparente diminuição do coeficiente de absorção capilar ao longo dos ensaios podem ser associadas aos processos de solubilização e recristalização da gipsita. No tempo de ciclagem estudado, o fenômeno não apresentou influência na resistência mecânica dos corpos-de-prova. / The crystallization of salts is an important and frequently observed pathology in masonry. However, it is still one of the least understood pathologies. The aim of this study is to evaluate the impact of florescence of soluble salts in ceramic blocks developed with phosphate sludge. For this purpose, blocks were molded with 0, 2.5% and 5% of phosphate sludge, which were sintered at temperatures of 750°C, 850°C, 950°C and 1050 ° C. The blocks were divided into two groups, one of which was kept under controlled temperature and humidity and the other was subjected to wetting and drying cycles. The groups were tested at 1, 30, 110 and 180 days. They were subjected to image analysis (binocular magnifying glass, graphic software and scanning electron microscopy), capillary water absorption, mercury intrusion porosimetry and flexural strength. The methods, x-ray diffraction, x-ray fluorescence and emission spectrometry, were used to investigate the phase and chemical composition. The results indicate the presence of aluminum, silicon, calcium, potassium, sulfur, iron and manganese, among which stands out the combination of sulfur and calcium. Thus, the gypsite is considered to be likely responsible for the soluble salts, whose deposits were found in varying extent and intensity, prevailing in the blocks with addition of waste. The variation in porosity and the apparent decrease in the coefficient of capillary absorption along the tests may be associated with the processes of solubilization and recrystallization. In cycling time studied, the phenomenon did not influence the mechanical strength of specimens.

O processo industrial não-contínuo de zincagem por imersão a quente (ZIQ) pode ocasionar a contaminação superficial do aço-carbono zincado por imersão a quente (AZIQ) com resíduos de cloreto. Estes resíduos, se não forem efetivamente eliminados, podem influenciar negativamente no desempenho dos esquemas de pintura dos sistemas dúplex (zincagem mais pintura). Sabe-se que no processo de ZIQ, a cromatização é amplamente utilizada, entretanto, o efeito que este pós-tratamento exerce no desempenho dos esquemas de pintura ainda não é bem estabelecido. Neste contexto, este trabalho teve como objetivos: I - verificar o grau de contaminação no AZIQ com sal de cloreto devido ao próprio processo de ZIQ; II - verificar os efeitos da contaminação com sal de cloreto e da cromatização do processo ZIQ no desempenho de tintas aplicadas sobre o AZIQ; e III – determinar pré-tratamentos para pintura adequados para o bom desempenho das tintas aplicadas sobre o AZIQ. A metodologia adotada para alcançar o objetivo I envolveu a zincagem de chapas de aço-carbono em diferentes prestadores de serviço de ZIQ, em diferentes condições. Estas chapas zincadas foram analisadas por microanálise química qualitativa por espectrometria de dispersão de energia (EDS) em microscópio eletrônico de varredura (MEV) e pela determinação dos teores de cloreto superficiais, por método de extração com água em ebulição. A partir dos resultados obtidos para se alcançar o objetivo I, foi possível definir as condições no processo de ZIQ que potencialmente causam maior contaminação da superfície do AZIQ com sal de cloreto. Assim, para se alcançar os objetivos II e III, chapas de aço-carbono foram zincadas naquelas condições de máxima contaminação com sal de cloreto e parte delas foi submetida ao pós-tratamento de cromatização. Em seguida, uma grande parte destas chapas zincadas (cromatizadas ou não) foi submetida aos pré-tratamentos para pintura de desengraxe com solvente orgânico, de hidrojateamento a alta pressão, de jateamento abrasivo ligeiro e de ação mecânica com esponja abrasiva e água quente. Finalmente, as chapas zincadas, incluindo as não submetidas aos pré-tratamentos, foram pintadas com uma demão de tinta de aderência mais uma demão de tinta de acabamento. As chapas zincadas e pintadas foram submetidas a ensaios acelerados (imersão em água destilada e exposição em câmara de umidade saturada) e não-acelerados de corrosão (exposição em estação de corrosão atmosférica) e avaliadas por meio dos ensaios tradicionais de acompanhamento de desempenho (grau de empolamento e ensaios de aderência de tinta) e eletroquímicos (medida de potencial de circuito aberto, curva de polarização e espectroscopia de impedância eletroquímica – E.I.E.). Algumas chapas zincadas, antes da pintura, foram submetidas aos ensaios de caracterização física (exame microestrutural e morfológico em MEV e rugosidade superficial), química microanálise por EDS, difração de raios X e teor de cloreto superficial pelo método de extração com água em ebulição) e eletroquímica. Os resultados obtidos, neste estudo, permitiram verificar que a aplicação adicional de sal cloreto de amônio sólido durante o processo de ZIQ tende a aumentar o grau de contaminação superficial do AZIQ com cloreto e, as etapas de resfriamento e/ou de cromatização do processo também contribuem para esta contaminação. No geral, o desempenho do AZIQ cromatizado teve desempenho inferior em relação ao não-cromatizados. O hidrojateamento a alta pressão e a lavagem com água e ação mecânica foram os prétratamentos que proporcionaram os melhores desempenhos dos esquemas de pintura. / The batch galvanizing process (BGP) can lead to surface contamination of hot-dip galvanized steel (HDGS) with chloride residues. If these residues are not effectively eliminated, they can influence negatively on the performance of duplex systems (galvanizing plus painting). It is known that the chromate quenching is widely used in the BGP, however the effect of this post-treatment on the performance of duplex systems is not well established yet. In this sense, this work aimed: I – to verify the contamination degree of HDGS with chloride salt due to the BGP itself; II – to verify the effects of the chloride salt contamination and chromate quenching on the performance of paints applied on HDGS; and III – to determine the suitable surface preparation for painting in order for obtaining a good paint performance applied on HDGS. The adopted methodology to achieve goal I involved the galvanizing of steel plates in different service renderings with BGP, in different conditions. These HDGS plates were submitted to the qualitative energy dispersive microanalyses (EDS) in scanning electron microscopy (SEM) and to the determination of superficial chloride contents by the boiling water extraction method. From the obtained results, the conditions in the BGP that potentially lead to greater surface contamination of HDGS with chloride salt were determined. Thus, to achieve goals II and III, steel plates were galvanized under the maximum chloride salt contamination condition and part of them were submitted to chromate quenching. After that, a great part of these HDGS plates (chromated or non chromated quenching) was submitted to the surface preparations for painting through organic solvent cleaning, high pressure hydroblasting, sweep blasting and handled scrub cleaning with an abrasive sponge and hot distilled water. Finally, the HDGS plates, including those not submitted to the surface preparations for painting, were painted with one coat of primer plus one coat of finishing paint. The HDGS painted plates were submitted to accelerated (distilled water immersion and humidity chamber exposure) and non accelerated (atmospheric exposure) corrosion tests and their performance were verified by means of traditional tests (degree of blistering and paint adhesion) and electrochemical measurements (open circuit potential, polarization curve and electrochemical impedance spectroscopy – E.I.S.). Before painting, some HDGS plates were submitted to tests for physical (microstructural and morphological analyses in MEV and surface roughness), chemical (EDS, X-ray diffraction and superficial chloride contents by the boiling water extraction method) and electrochemical characterization. The obtained results allowed verifying that the additional application of solid ammonium chloride salt during the BGP tends to increase the degree of superficial chloride contamination of the HDGS and, the water and/or chromate quenching also contribute for this contamination. In general, the chromated HDGS presented worst performances. The high pressure hydroblasting and the handled scrub cleaning with an abrasive sponge and hot distilled water were the surface preparations for painting that provided the best performances of paint systems.

O processo industrial não-contínuo de zincagem por imersão a quente (ZIQ) pode ocasionar a contaminação superficial do aço-carbono zincado por imersão a quente (AZIQ) com resíduos de cloreto. Estes resíduos, se não forem efetivamente eliminados, podem influenciar negativamente no desempenho dos esquemas de pintura dos sistemas dúplex (zincagem mais pintura). Sabe-se que no processo de ZIQ, a cromatização é amplamente utilizada, entretanto, o efeito que este pós-tratamento exerce no desempenho dos esquemas de pintura ainda não é bem estabelecido. Neste contexto, este trabalho teve como objetivos: I - verificar o grau de contaminação no AZIQ com sal de cloreto devido ao próprio processo de ZIQ; II - verificar os efeitos da contaminação com sal de cloreto e da cromatização do processo ZIQ no desempenho de tintas aplicadas sobre o AZIQ; e III – determinar pré-tratamentos para pintura adequados para o bom desempenho das tintas aplicadas sobre o AZIQ. A metodologia adotada para alcançar o objetivo I envolveu a zincagem de chapas de aço-carbono em diferentes prestadores de serviço de ZIQ, em diferentes condições. Estas chapas zincadas foram analisadas por microanálise química qualitativa por espectrometria de dispersão de energia (EDS) em microscópio eletrônico de varredura (MEV) e pela determinação dos teores de cloreto superficiais, por método de extração com água em ebulição. A partir dos resultados obtidos para se alcançar o objetivo I, foi possível definir as condições no processo de ZIQ que potencialmente causam maior contaminação da superfície do AZIQ com sal de cloreto. Assim, para se alcançar os objetivos II e III, chapas de aço-carbono foram zincadas naquelas condições de máxima contaminação com sal de cloreto e parte delas foi submetida ao pós-tratamento de cromatização. Em seguida, uma grande parte destas chapas zincadas (cromatizadas ou não) foi submetida aos pré-tratamentos para pintura de desengraxe com solvente orgânico, de hidrojateamento a alta pressão, de jateamento abrasivo ligeiro e de ação mecânica com esponja abrasiva e água quente. Finalmente, as chapas zincadas, incluindo as não submetidas aos pré-tratamentos, foram pintadas com uma demão de tinta de aderência mais uma demão de tinta de acabamento. As chapas zincadas e pintadas foram submetidas a ensaios acelerados (imersão em água destilada e exposição em câmara de umidade saturada) e não-acelerados de corrosão (exposição em estação de corrosão atmosférica) e avaliadas por meio dos ensaios tradicionais de acompanhamento de desempenho (grau de empolamento e ensaios de aderência de tinta) e eletroquímicos (medida de potencial de circuito aberto, curva de polarização e espectroscopia de impedância eletroquímica – E.I.E.). Algumas chapas zincadas, antes da pintura, foram submetidas aos ensaios de caracterização física (exame microestrutural e morfológico em MEV e rugosidade superficial), química microanálise por EDS, difração de raios X e teor de cloreto superficial pelo método de extração com água em ebulição) e eletroquímica. Os resultados obtidos, neste estudo, permitiram verificar que a aplicação adicional de sal cloreto de amônio sólido durante o processo de ZIQ tende a aumentar o grau de contaminação superficial do AZIQ com cloreto e, as etapas de resfriamento e/ou de cromatização do processo também contribuem para esta contaminação. No geral, o desempenho do AZIQ cromatizado teve desempenho inferior em relação ao não-cromatizados. O hidrojateamento a alta pressão e a lavagem com água e ação mecânica foram os prétratamentos que proporcionaram os melhores desempenhos dos esquemas de pintura. / The batch galvanizing process (BGP) can lead to surface contamination of hot-dip galvanized steel (HDGS) with chloride residues. If these residues are not effectively eliminated, they can influence negatively on the performance of duplex systems (galvanizing plus painting). It is known that the chromate quenching is widely used in the BGP, however the effect of this post-treatment on the performance of duplex systems is not well established yet. In this sense, this work aimed: I – to verify the contamination degree of HDGS with chloride salt due to the BGP itself; II – to verify the effects of the chloride salt contamination and chromate quenching on the performance of paints applied on HDGS; and III – to determine the suitable surface preparation for painting in order for obtaining a good paint performance applied on HDGS. The adopted methodology to achieve goal I involved the galvanizing of steel plates in different service renderings with BGP, in different conditions. These HDGS plates were submitted to the qualitative energy dispersive microanalyses (EDS) in scanning electron microscopy (SEM) and to the determination of superficial chloride contents by the boiling water extraction method. From the obtained results, the conditions in the BGP that potentially lead to greater surface contamination of HDGS with chloride salt were determined. Thus, to achieve goals II and III, steel plates were galvanized under the maximum chloride salt contamination condition and part of them were submitted to chromate quenching. After that, a great part of these HDGS plates (chromated or non chromated quenching) was submitted to the surface preparations for painting through organic solvent cleaning, high pressure hydroblasting, sweep blasting and handled scrub cleaning with an abrasive sponge and hot distilled water. Finally, the HDGS plates, including those not submitted to the surface preparations for painting, were painted with one coat of primer plus one coat of finishing paint. The HDGS painted plates were submitted to accelerated (distilled water immersion and humidity chamber exposure) and non accelerated (atmospheric exposure) corrosion tests and their performance were verified by means of traditional tests (degree of blistering and paint adhesion) and electrochemical measurements (open circuit potential, polarization curve and electrochemical impedance spectroscopy – E.I.S.). Before painting, some HDGS plates were submitted to tests for physical (microstructural and morphological analyses in MEV and surface roughness), chemical (EDS, X-ray diffraction and superficial chloride contents by the boiling water extraction method) and electrochemical characterization. The obtained results allowed verifying that the additional application of solid ammonium chloride salt during the BGP tends to increase the degree of superficial chloride contamination of the HDGS and, the water and/or chromate quenching also contribute for this contamination. In general, the chromated HDGS presented worst performances. The high pressure hydroblasting and the handled scrub cleaning with an abrasive sponge and hot distilled water were the surface preparations for painting that provided the best performances of paint systems.

<p>Дивљи кестен (Aesculus hippocastanum L.) је ендемит јужног дела Балканског полуострва. Веома је интересантна врста лишћара за изучавање секундарних популација на зеленим просторима Србије и производњу садног материјала за потребе хортикултуре и пејзажне архитектуре. Циљ истраживања је издвајање генотипова дивљег кестена из секундарних популација које су засноване на зеленим просторима Војводине у виду алејних засада, као појединачна стабла или групе. Критеријуми за вредновање генотипова као семенских објеката у хортикултури, обављени су на основу референце Стилиновић и Туцовић (1977). Биолошке одлике генотипова треба да усмере критеријуме за производњу квалитетног садног материјала дивљег кестена, адаптивност на услове урбане средине и стрес узрокован абиотским факторима. У селекционом периоду који је трајао од 2008. до 2010. године (Чукановић, 2010) евидентирано је и оцењено 50 генотипова на три локалитетa: Бачка Паланка, Нови Сад и Сремски Карловци. Сакупљено је семе, урађена је анализа лабораторијске и теренске клијавости и морфолошка карактеризација показатеља раста сејанаца. Истовремено је одређиван хемијски састав семена. У току трогодишњег периода (од 2011 до 2013. године), на основу резултата претходних истраживања, издвојено је 17 генотипова са најбољим биолошким, производним и лековитим особинама семена. На одабраним индивидуама праћене су фенолошке фазе - листање, цветање и плодоношења са међуфазама. Сакупљано је семе ради утврђивања морфолошких и хемијских карактеристика. Матична стабла се одликују разликама у физиолошкој зрелости, особинама фенотипа и употребне вредности семена за расадничку производњу. Праћено је генеративно умножавање генотипова и анализа показатеља раста half-sib потомства. Семе дивљег кестена је значајна сировина у фарамацеутској индустрији с обзиром да има лековита својства. Урађен је хемијски састав семена, са акцентом на садржај уља и структуру масних киселина, секундарне метаболите и тешке метале. Акумулација тешких метала у семену дивљег кестена присутна је у популацијама секундарног порекла, с обзиром да су матична стабла изложена утицају градске средине.Земљишта урбаних зелених простора (урбисол) изложена су загађењу што је разлог више да се испита утицај водорастворљивих соли и тешких метала на адаптивност генотипова. Фенолошким осматрањем листања, цветања и плодоношења у току трогодишњег периода забележене су значајне статистичке разлике између година испитивања и генотипова. Због дужег периода ниских температура у марту и априлу 2013. године, запажена је значајна разлика у почецима и трајању фенофаза и међуфаза. Осматране фенолошке појаве касниле су 2 до 3 недеље. Генотипови БДС1 и БДС2, у периоду трогодишњег осматрања, одликовали су се значајно ранијим наступањем фазе листања и цветања, док је код генотипова БП4, СК4 и СК7 забележено касније ступање обе фазе. Експериментална стабла, као издвојени семенски објекти за потребе хортикултуре и пејзажне архитектуре, редовно и обилно плодоносе. На основу морфолошких особина семена издвајају се генотипови П6 (са високим вредностима за дужину /29,83mm/, ширину /35,56 mm/ и дебљину /30,92 mm/) и П3 (са високом вредности за масу семена /17,63 g/). Чување семена за потребе расадничке производње обављено је у хладној комори при контролисаним условима на температури од 4 до 6&deg;С. Сетва је обављана у пролећном периоду (март-април). За семенски материјал 17 генотипова, за трогодишњи период, установљена је веома висока теренска клијавост која у просеку износи од 80,94% до 85,64%. Проценат преживљавања сејанаца, одређен при крају вегетационог периода и почетка нове вегетације, износи од 78,96 дo 82,98. Мерењем показатеља раста једногодишњих сејанаца установљене су просечне вредности за висину (12,26 cm), пречник у кореновом врату (10,04 mm), дужину корена (12,87 cm), масу стабла (3,62 g), масу корена (5,34 g) и број коренова I реда (26,49). Истиче се генотип БДС1 са високим вредностима за мерене показатеље (19,20 cm за висину, 17,51 cm за дужину корена, 4,40 g за масу стабла и 6,80 g за масу корена). Према показатељима раста двогодишњих сејанаца за висину издвојили су се генотипови БДС1 (30,20 cm), БДС2 (35,80 cm) и СК4 (35,68 cm). Највише вредности за пречник при основи стабла имали су генотипови БДС1 (19,20 mm) и БДС2 (19,33 mm). Просечна вредност за висину надземног дела генотипова трогодишњих биљака била је 81,45 cm, а за пречник при основи стабла 26,81 mm. У трећој години развоја сејанаца дивљег кестена in situ у расаднику на Римским Шанчевима, највише вредности за висину и пречник при основи стабла имали су генотипови ознака БДС1 (92,00 cm и 29,55 mm), БДС2 (90,80 cm и 31,27 mm) и СК4 (91,30 cm и 28,45 mm). Снага раста двогодишњих сејанаца издвојила је генотипове БДС1, БДС2 и СК4, који су имали изузетан пораст и треће године развоја у сејалишту. На двогодишњим и трогодишњим садницама генотипова БП4, БП5, БДС1, БДС2, П5, П6, СК1 и СК4 обављено је калемљење хибрида црвеног кестена (Aesculus &times; carnea Hayne.). Испољена је компатибилност подлога са племкама, а просечан пријем калемова био је 82,36%. Примењена метода енглеског спајања показала је добре резултате као вегетативна метода за производњу садног материјала хибрида црвеног кестена.</p><p>Из екстракта семена генотипова дивљег кестена изоловано је и детерминисано 16 масних киселина. Утврђен је висок удео незасићених масних киселина, а као доминантна издваја се олеинска. Највиши садржај установљен је у семену генотипа БДС1 (59,10%). Генотипови П5 и СК1 одликују се највишим вредностима кверцетина (0,538 &mu;g/g, односно 0,806 &mu;g/g), кемферола (0,227&mu;g/g и 0,429 &mu;g/g), а генотип П5 и<br />рутина(25,784&mu;g/g). Есцин је присутан у семену свих испитиваних генотипова, са највишим просечним садржајем у семену генотипова БП2 и П5 (4,04%). У узорку семена, од тешких метала забележен је висок просечни садржај цинка (10,11 &mu;/g) и бакра (9,23 &mu;/g). Издваја се генотип П5 са највишим просечним садржајем алуминијума (2,88 &mu;/g) и хрома (0,1 &mu;/g) у семену, док су највише вредности бакра (13,0 &mu;/g), гвожђа (13,2 &mu;/g), мангана (3,2 &mu;/g), никла (0,8 &mu;/g) и цинка (18,1 &mu;/g) забележене у семену генотипа П1. У узорцима земљишта дуж саобраћајнице Булевар Јаше Томића у Новом Саду, у дрвореду дивљег кестена, утврђен је садржај водорастворљивих соли и тешких метала. Просечне вредности садржаја соли у узорцима сондираним у априлу износе 0,10% на дубини од 0 до 30 cm, односно 0,11% на дубини од 30 до 60 cm, што је испод детерминисане горње границе. Узорци сондирани у августу 2012. године имали су виши садржај од дозвољеног (0,24% на дубини од 0 до 30 cm и 0,27% на дубини од 30 до 60 cm), што је последица асцендентног кретања соли услед суше. Као последица високог садржаја соли јавља се лисна хлороза, некроза, поновљено цветање и смањена виталност стабала. Анализа тешких метала (Fe, Zn, Mn, Cu, Cd, Co, Ni, Pb и Cr), из узорака земљишта, показала је њихово присуство у лакоприступачном и укупном облику, али не изнад дозвољених граничних вредности за еколошке услове Новог Сада. Упознавање биолошког и производног потенцијала дивљег кестена представља важну полазну основу за унапређење расадничке производње и примене дивљег кестена за потребе хортикултуре и пејзажне архитекутре.</p> / <p>Divlji kesten (Aesculus hippocastanum L.) je endemit južnog dela Balkanskog poluostrva. Veoma je interesantna vrsta lišćara za izučavanje sekundarnih populacija na zelenim prostorima Srbije i proizvodnju sadnog materijala za potrebe hortikulture i pejzažne arhitekture. Cilj istraživanja je izdvajanje genotipova divljeg kestena iz sekundarnih populacija koje su zasnovane na zelenim prostorima Vojvodine u vidu alejnih zasada, kao pojedinačna stabla ili grupe. Kriterijumi za vrednovanje genotipova kao semenskih objekata u hortikulturi, obavljeni su na osnovu reference Stilinović i Tucović (1977). Biološke odlike genotipova treba da usmere kriterijume za proizvodnju kvalitetnog sadnog materijala divljeg kestena, adaptivnost na uslove urbane sredine i stres uzrokovan abiotskim faktorima. U selekcionom periodu koji je trajao od 2008. do 2010. godine (Čukanović, 2010) evidentirano je i ocenjeno 50 genotipova na tri lokaliteta: Bačka Palanka, Novi Sad i Sremski Karlovci. Sakupljeno je seme, urađena je analiza laboratorijske i terenske klijavosti i morfološka karakterizacija pokazatelja rasta sejanaca. Istovremeno je određivan hemijski sastav semena. U toku trogodišnjeg perioda (od 2011 do 2013. godine), na osnovu rezultata prethodnih istraživanja, izdvojeno je 17 genotipova sa najboljim biološkim, proizvodnim i lekovitim osobinama semena. Na odabranim individuama praćene su fenološke faze - listanje, cvetanje i plodonošenja sa međufazama. Sakupljano je seme radi utvrđivanja morfoloških i hemijskih karakteristika. Matična stabla se odlikuju razlikama u fiziološkoj zrelosti, osobinama fenotipa i upotrebne vrednosti semena za rasadničku proizvodnju. Praćeno je generativno umnožavanje genotipova i analiza pokazatelja rasta half-sib potomstva. Seme divljeg kestena je značajna sirovina u faramaceutskoj industriji s obzirom da ima lekovita svojstva. Urađen je hemijski sastav semena, sa akcentom na sadržaj ulja i strukturu masnih kiselina, sekundarne metabolite i teške metale. Akumulacija teških metala u semenu divljeg kestena prisutna je u populacijama sekundarnog porekla, s obzirom da su matična stabla izložena uticaju gradske sredine.Zemljišta urbanih zelenih prostora (urbisol) izložena su zagađenju što je razlog više da se ispita uticaj vodorastvorljivih soli i teških metala na adaptivnost genotipova. Fenološkim osmatranjem listanja, cvetanja i plodonošenja u toku trogodišnjeg perioda zabeležene su značajne statističke razlike između godina ispitivanja i genotipova. Zbog dužeg perioda niskih temperatura u martu i aprilu 2013. godine, zapažena je značajna razlika u počecima i trajanju fenofaza i međufaza. Osmatrane fenološke pojave kasnile su 2 do 3 nedelje. Genotipovi BDS1 i BDS2, u periodu trogodišnjeg osmatranja, odlikovali su se značajno ranijim nastupanjem faze listanja i cvetanja, dok je kod genotipova BP4, SK4 i SK7 zabeleženo kasnije stupanje obe faze. Eksperimentalna stabla, kao izdvojeni semenski objekti za potrebe hortikulture i pejzažne arhitekture, redovno i obilno plodonose. Na osnovu morfoloških osobina semena izdvajaju se genotipovi P6 (sa visokim vrednostima za dužinu /29,83mm/, širinu /35,56 mm/ i debljinu /30,92 mm/) i P3 (sa visokom vrednosti za masu semena /17,63 g/). Čuvanje semena za potrebe rasadničke proizvodnje obavljeno je u hladnoj komori pri kontrolisanim uslovima na temperaturi od 4 do 6&deg;S. Setva je obavljana u prolećnom periodu (mart-april). Za semenski materijal 17 genotipova, za trogodišnji period, ustanovljena je veoma visoka terenska klijavost koja u proseku iznosi od 80,94% do 85,64%. Procenat preživljavanja sejanaca, određen pri kraju vegetacionog perioda i početka nove vegetacije, iznosi od 78,96 do 82,98. Merenjem pokazatelja rasta jednogodišnjih sejanaca ustanovljene su prosečne vrednosti za visinu (12,26 cm), prečnik u korenovom vratu (10,04 mm), dužinu korena (12,87 cm), masu stabla (3,62 g), masu korena (5,34 g) i broj korenova I reda (26,49). Ističe se genotip BDS1 sa visokim vrednostima za merene pokazatelje (19,20 cm za visinu, 17,51 cm za dužinu korena, 4,40 g za masu stabla i 6,80 g za masu korena). Prema pokazateljima rasta dvogodišnjih sejanaca za visinu izdvojili su se genotipovi BDS1 (30,20 cm), BDS2 (35,80 cm) i SK4 (35,68 cm). Najviše vrednosti za prečnik pri osnovi stabla imali su genotipovi BDS1 (19,20 mm) i BDS2 (19,33 mm). Prosečna vrednost za visinu nadzemnog dela genotipova trogodišnjih biljaka bila je 81,45 cm, a za prečnik pri osnovi stabla 26,81 mm. U trećoj godini razvoja sejanaca divljeg kestena in situ u rasadniku na Rimskim Šančevima, najviše vrednosti za visinu i prečnik pri osnovi stabla imali su genotipovi oznaka BDS1 (92,00 cm i 29,55 mm), BDS2 (90,80 cm i 31,27 mm) i SK4 (91,30 cm i 28,45 mm). Snaga rasta dvogodišnjih sejanaca izdvojila je genotipove BDS1, BDS2 i SK4, koji su imali izuzetan porast i treće godine razvoja u sejalištu. Na dvogodišnjim i trogodišnjim sadnicama genotipova BP4, BP5, BDS1, BDS2, P5, P6, SK1 i SK4 obavljeno je kalemljenje hibrida crvenog kestena (Aesculus &times; carnea Hayne.). Ispoljena je kompatibilnost podloga sa plemkama, a prosečan prijem kalemova bio je 82,36%. Primenjena metoda engleskog spajanja pokazala je dobre rezultate kao vegetativna metoda za proizvodnju sadnog materijala hibrida crvenog kestena.</p><p>Iz ekstrakta semena genotipova divljeg kestena izolovano je i determinisano 16 masnih kiselina. Utvrđen je visok udeo nezasićenih masnih kiselina, a kao dominantna izdvaja se oleinska. Najviši sadržaj ustanovljen je u semenu genotipa BDS1 (59,10%). Genotipovi P5 i SK1 odlikuju se najvišim vrednostima kvercetina (0,538 &mu;g/g, odnosno 0,806 &mu;g/g), kemferola (0,227&mu;g/g i 0,429 &mu;g/g), a genotip P5 i<br />rutina(25,784&mu;g/g). Escin je prisutan u semenu svih ispitivanih genotipova, sa najvišim prosečnim sadržajem u semenu genotipova BP2 i P5 (4,04%). U uzorku semena, od teških metala zabeležen je visok prosečni sadržaj cinka (10,11 &mu;/g) i bakra (9,23 &mu;/g). Izdvaja se genotip P5 sa najvišim prosečnim sadržajem aluminijuma (2,88 &mu;/g) i hroma (0,1 &mu;/g) u semenu, dok su najviše vrednosti bakra (13,0 &mu;/g), gvožđa (13,2 &mu;/g), mangana (3,2 &mu;/g), nikla (0,8 &mu;/g) i cinka (18,1 &mu;/g) zabeležene u semenu genotipa P1. U uzorcima zemljišta duž saobraćajnice Bulevar Jaše Tomića u Novom Sadu, u drvoredu divljeg kestena, utvrđen je sadržaj vodorastvorljivih soli i teških metala. Prosečne vrednosti sadržaja soli u uzorcima sondiranim u aprilu iznose 0,10% na dubini od 0 do 30 cm, odnosno 0,11% na dubini od 30 do 60 cm, što je ispod determinisane gornje granice. Uzorci sondirani u avgustu 2012. godine imali su viši sadržaj od dozvoljenog (0,24% na dubini od 0 do 30 cm i 0,27% na dubini od 30 do 60 cm), što je posledica ascendentnog kretanja soli usled suše. Kao posledica visokog sadržaja soli javlja se lisna hloroza, nekroza, ponovljeno cvetanje i smanjena vitalnost stabala. Analiza teških metala (Fe, Zn, Mn, Cu, Cd, Co, Ni, Pb i Cr), iz uzoraka zemljišta, pokazala je njihovo prisustvo u lakopristupačnom i ukupnom obliku, ali ne iznad dozvoljenih graničnih vrednosti za ekološke uslove Novog Sada. Upoznavanje biološkog i proizvodnog potencijala divljeg kestena predstavlja važnu polaznu osnovu za unapređenje rasadničke proizvodnje i primene divljeg kestena za potrebe hortikulture i pejzažne arhitekutre.</p> / <p>(25,784&mu;g/g). Есцин је присутан у семену свих испитиваних генотипова, са највишим просечним садржајем у семену генотипова БП2 и П5 (4,04%). У узорку семена, од тешких метала забележен је висок просечни садржај цинка (10,11 &mu;/g) и бакра (9,23 &mu;/g). Издваја се генотип П5 са највишим просечним садржајем алуминијума (2,88 &mu;/g) и хрома (0,1 &mu;/g) у семену, док су највише вредности бакра (13,0 &mu;/g), гвожђа (13,2 &mu;/g), мангана (3,2 &mu;/g), никла (0,8 &mu;/g) и цинка (18,1 &mu;/g) забележене у семену генотипа П1. У узорцима земљишта дуж саобраћајнице Булевар Јаше Томића у Новом Саду, у дрвореду дивљег кестена, утврђен је садржај водорастворљивих соли и тешких метала. Просечне вредности садржаја соли у узорцима сондираним у априлу износе 0,10% на дубини од 0 до 30 cm, односно 0,11% на дубини од 30 до 60 cm, што је испод детерминисане горње границе. Узорци сондирани у августу 2012. године имали су виши садржај од дозвољеног (0,24% на дубини од 0 до 30 cm и 0,27% на дубини од 30 до 60 cm), што је последица асцендентног кретања соли услед суше. Као последица високог садржаја соли јавља се лисна хлороза, некроза, поновљено цветање и смањена виталност стабала. Анализа тешких метала (Fe, Zn, Mn, Cu, Cd, Co, Ni, Pb и Cr), из узорака земљишта, показала је њихово присуство у лакоприступачном и укупном облику, али не изнад дозвољених граничних вредности за еколошке услове Новог Сада. Упознавање биолошког и производног потенцијала дивљег кестена представља важну полазну основу за унапређење расадничке производње и примене дивљег кестена за потребе хортикултуре и пејзажне архитекутре.</p>

The current study therefore aims to provide a comprehensive characterisation of weathered dry disposed ash cores, to reveal mobility patterns of chemical species as a function of depth and age of ash, with a view to assessing the potential environmental impacts. Fifty-nine samples were taken from 3 drilled cores obtained respectively from the 1 year, 8 year and 20-year-old sections of sequentially dumped, weathered, dry disposed ash in an ash dump site at Tutuka - a South African coal burning power station.

<p>The management and disposal of huge volumes of coal combustion by products such as fly ash has constituted a major challenge to the environment. In most cases due to the inadequate alternative use of coal fly ash, the discarded waste is stored in holding ponds, slag heaps, or stock piled in ash dumps. This practice has raised concerns on the prospect of inorganic metals release to the surface and groundwater in the vicinity of the ash dump. Acceptable scientific studies are lacking to determine the best ash disposal practices. Moreover, knowledge about the mobility patterns of inorganic species as a function of mineralogical association or pH susceptibility of the dry disposed ash dump under natural weathering conditions are scarce in the literature. Fundamental understanding of chemical interactions of dry disposed ash with ingressed CO2 from atmosphere, percolating rain water and brine irrigation within ash disposal sites were seen as key areas requiring investigation. The mineralogical association of inorganic species in the dry disposed ash cores can be identified and quantified. This would provide a basis for understanding of chemical weathering, mineralogical transformations or mobility patterns of these inorganic species in the dry ash disposal scenario. The current study therefore aims to provide a comprehensive characterisation of weathered dry disposed ash cores, to reveal mobility patterns of chemical species as a function of depth and age of ash, with a view to assessing the potential environmental impacts. Fifty-nine samples were taken from 3 drilled cores obtained respectively from the 1 year, 8 year and 20-year-old sections of sequentially dumped,&nbsp / weathered, dry disposed ash in an ash dump site at Tutuka - a South African coal burning power station. The core samples were characterized using standard analytical procedures viz: X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) techniques, Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and Acid neutralisation capacity (ANC) test. A modified sequential extraction (SE) method was used in this study. The chemical partitioning, mobility and weathering patterns in 1 year, 8 year and 20-year-old sections of the ash dump were respectively investigated using this modified sequential extraction scheme. The sequence of the extractions was as follows: (1) water soluble, (2) exchangeable, (3) carbonate, (4) iron and manganese and (5) residual. The results obtained from the 5 steps sequential extraction scheme were validated with the total metal content of the original sample using mass balance method. The distribution of major and trace elements in the different liquid fractions obtained after each step of sequential extraction of the 59 drilled core samples was determined by inductively coupled plasma mass spectrometry (ICPMS). The data generated for various ash core samples were explored for the systematic analysis of mineralogical transformation and change in ash chemistry with ageing of the ash. Furthermore, the data was analyzed to reveal the impact of ingressed CO2 from atmosphere, infiltrating rain water and brine irrigation on the chemistry of ash core samples. Major mineral phases in original ash core samples prior to extraction are quartz (SiO2) and mullite (3Al2O3&middot / 2SiO2). Other minor mineral phases identified were hematite (Fe2O3), calcite (CaCO3), lime (CaO), anorthite (CaAl2Si2O8), mica (Ca (Mg, Al)3 (Al3Si) O10 (OH)2), and enstatite (Mg2Si2O6). X-ray diffraction results show significant loss of crystallinity in the older ash cores. The presence of minor phases of calcite and mica in dry disposed ash cores are attributed to reduction in the pore water pH due to hydration, carbonation and pozzolanic reactions. The X-ray diffraction technique was unable to detect Fe-oxyhydroxide phase and morealuminosilicate phases in ash core samples due to their low abundance and amorphous character. X-ray fluorescence results of the original ash core samples showed the presence of major oxides, such as SiO2, Al2O3, Fe2O3, while CaO, K2O, TiO2, Na2O, MnO, MgO, P2O5, and SO3 occur in minor concentrations. The ratio of SiO2/Al2O3 classified the original core samples prior to extraction as a silico-aluminate class F fly ash. The ternary plot of major elements in 1-year-old ash core samples was both sialic and ferrocalsialic but 8 year and 20-year-old ash core samples were sialic in chemical composition. It is noteworthy that the mass % of SiO2 varies through the depth of the core with an increase of nearly 3 %, to 58 mass % of SiO2 at a depth of 6 m in the 1-year-old core whereas in the case of the 8-year-old core a 2 % increase of SiO2 to a level of 57.5 mass % can be observed at levels between 4-8 m, showing dissolution of major components in the matrix of older ash cores.. The Na2O content of the Tutuka ash cores was low and varied between 0.6-1.1 mass % for 1-year-old ash cores to around 0.6-0.8 mass % for 8-year-old ash cores. Sodium levels were higher in 1-year-old ash cores compared to 8 year and 20-year-old ashcores. Observed trends indicate that quick weathering of the ash (within a year) leached out Na+ from the ash dump. No evidence of Na+ encapsulation even though the ash dump was brine irrigated. Thus the dry disposal ash placement method does not result in a sustainable salt sink for Na-containing species over time. The total content of each of the elements in 1 year and 20-year-old ash cores was normalised with their total content in fresh ash from same power station to show enrichment and depletion factor. Major elements such as K+, Mn showed enrichment in 1-year-old ash cores whereas Al, Si, Na+, Ti, Ca, Mg, S and Fe showed depletion due to over time erosion. Trace elements such as Cr, Sr, P, Ba, Pb, V and Zn showed enrichment but Ni, Y, Zr showed depletion attributed to over time erosion. In 20-year-old ash cores, major elements such as Al, Na+ and Mn showed enrichment while Si, K+, Fe, Mg and Ca showed depletion highlighting their mobility. Trends indicated intensive flushing of major soluble components such as buffering constituents (CaO) by percolating rain water. The 1-year-old and 20-year-old coal ash cores showed a lower pH and greater loss/depletion of the soluble buffering constituents than the 2-week-old placed ash, indicating significant chemical weathering within a year. Based&nbsp / on ANC results the leaching behaviours of Ca, Mg, Na+, K+, Se, Cr, and Sr were found to be controlled by the pH of the leachant indicating high mobility of major soluble species in the ash cores when in contact with slightly acid rain water. Other investigated toxic metals such as As, Mo and Pb showed amphoteric behaviour with respect to the pH of the leachant. Chemical alterations and formation of transient minor secondary mineral phases was found to have a significant effect on the acid susceptibility and depletion pattern of chemical species in the core ash samples when compared to fresh ash. These ANC results correlated well with the data generated from the sequential extraction scheme. Based on sequential extraction results elements, showed noticeable mobility in the water soluble, exchangeable and carbonate fractions due to adsorption and desorption caused by variations in the pore water pH. In contrast, slight mobility of elements in the Fe and Mn, and residual fractions of dry disposed fly ashes are attributed to the co-precipitation and dissolution of minor amount of less soluble secondary phase overtime. The 1-year-old dry disposed ash cores were the least weathered among the 3 drilled ash cores. Therefore low concentration of toxic metals in older ash cores were ascribed to extensive weathering with slower release from residual mineral phases over time. Elements were found to associate with different mineral phases depending on the age or depth of the core samples showing greater heterogeneity in dispersion. For instance the average amount of total calcium in different mineral associations of 1-year-old ash cores is as follows / water soluble (10.2 %), exchangeable (37.04 %), carbonate (37.9 %), Fe and Mn (7.1 %) and residual (2.97 %). The amount of total Na+ in different mineral phases of 1-year-old ash cores followed this trend: water soluble (21 %), exchangeable (11.26 %), carbonate (2.6 %), Fe and Mn (4.7 %) and residual (53.9 %). The non-leachable portion of the total Na+ content (namely that contained in the residual fraction) in the 1-year-old ash core samples under conditions found in nature ranged between 5-91 %. This non-leachable portion of the Na+ showed the metastability of the mineral phases with which residual Na+ associates. Results showed older ash cores are enriched in toxic elements. Toxic elements such as As, B, Cr, Mo and Pb are enriched in the residual fraction of older ash cores. For instance As concentration in the residual fraction varied between 0.0003- 0.00043 mg kg-1 for 1-year-old ash cores to around 0.0003-0.0015 mg kg-1 for 20-year-old ash cores. This suggests that the older ash is enriched in toxic elements hence dust from the ash dump would be toxic to human health. The knowledge of mobility and ecotoxicological significance of coal fly ash is needed when considering its disposal or reuse in the environment. The mobility and ecotoxicology of inorganic metals in coal fly ash are determined by (i) mineralogical associations of inorganic species (ii) in-homogeneity in the ash dumps (iii) long and short term exposure to ingress CO2 and percolating rain water. Management issues such as inconsistent placement of ash in the dumps, poor choice of ash dump site, in-homogeneity in brine irrigation, no record of salt load put on the ash dumps and lack of proper monitoring requires improvement. The thesis provides justification for the use of the modified sequential extraction scheme as a predictive tool and could be employed in a similar research work. This thesis also proved that the dry ash disposal method was not environmental friendly in terms of overall leaching potential after significant chemical weathering. Moreover the study proved that the practice of brine co-disposal or irrigation on ash dumps is not sustainable as the ash dump did not act as a salt sink.</p>

<p>The management and disposal of huge volumes of coal combustion by products such as fly ash has constituted a major challenge to the environment. In most cases due to the inadequate alternative use of coal fly ash, the discarded waste is stored in holding ponds, slag heaps, or stock piled in ash dumps. This practice has raised concerns on the prospect of inorganic metals release to the surface and groundwater in the vicinity of the ash dump. Acceptable scientific studies are lacking to determine the best ash disposal practices. Moreover, knowledge about the mobility patterns of inorganic species as a function of mineralogical association or pH susceptibility of the dry disposed ash dump under natural weathering conditions are scarce in the literature. Fundamental understanding of chemical interactions of dry disposed ash with ingressed CO2 from atmosphere, percolating rain water and brine irrigation within ash disposal sites were seen as key areas requiring investigation. The mineralogical association of inorganic species in the dry disposed ash cores can be identified and quantified. This would provide a basis for understanding of chemical weathering, mineralogical transformations or mobility patterns of these inorganic species in the dry ash disposal scenario. The current study therefore aims to provide a comprehensive characterisation of weathered dry disposed ash cores, to reveal mobility patterns of chemical species as a function of depth and age of ash, with a view to assessing the potential environmental impacts. Fifty-nine samples were taken from 3 drilled cores obtained respectively from the 1 year, 8 year and 20-year-old sections of sequentially dumped,&nbsp / weathered, dry disposed ash in an ash dump site at Tutuka - a South African coal burning power station. The core samples were characterized using standard analytical procedures viz: X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) techniques, Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and Acid neutralisation capacity (ANC) test. A modified sequential extraction (SE) method was used in this study. The chemical partitioning, mobility and weathering patterns in 1 year, 8 year and 20-year-old sections of the ash dump were respectively investigated using this modified sequential extraction scheme. The sequence of the extractions was as follows: (1) water soluble, (2) exchangeable, (3) carbonate, (4) iron and manganese and (5) residual. The results obtained from the 5 steps sequential extraction scheme were validated with the total metal content of the original sample using mass balance method. The distribution of major and trace elements in the different liquid fractions obtained after each step of sequential extraction of the 59 drilled core samples was determined by inductively coupled plasma mass spectrometry (ICPMS). The data generated for various ash core samples were explored for the systematic analysis of mineralogical transformation and change in ash chemistry with ageing of the ash. Furthermore, the data was analyzed to reveal the impact of ingressed CO2 from atmosphere, infiltrating rain water and brine irrigation on the chemistry of ash core samples. Major mineral phases in original ash core samples prior to extraction are quartz (SiO2) and mullite (3Al2O3&middot / 2SiO2). Other minor mineral phases identified were hematite (Fe2O3), calcite (CaCO3), lime (CaO), anorthite (CaAl2Si2O8), mica (Ca (Mg, Al)3 (Al3Si) O10 (OH)2), and enstatite (Mg2Si2O6). X-ray diffraction results show significant loss of crystallinity in the older ash cores. The presence of minor phases of calcite and mica in dry disposed ash cores are attributed to reduction in the pore water pH due to hydration, carbonation and pozzolanic reactions. The X-ray diffraction technique was unable to detect Fe-oxyhydroxide phase and morealuminosilicate phases in ash core samples due to their low abundance and amorphous character. X-ray fluorescence results of the original ash core samples showed the presence of major oxides, such as SiO2, Al2O3, Fe2O3, while CaO, K2O, TiO2, Na2O, MnO, MgO, P2O5, and SO3 occur in minor concentrations. The ratio of SiO2/Al2O3 classified the original core samples prior to extraction as a silico-aluminate class F fly ash. The ternary plot of major elements in 1-year-old ash core samples was both sialic and ferrocalsialic but 8 year and 20-year-old ash core samples were sialic in chemical composition. It is noteworthy that the mass % of SiO2 varies through the depth of the core with an increase of nearly 3 %, to 58 mass % of SiO2 at a depth of 6 m in the 1-year-old core whereas in the case of the 8-year-old core a 2 % increase of SiO2 to a level of 57.5 mass % can be observed at levels between 4-8 m, showing dissolution of major components in the matrix of older ash cores.. The Na2O content of the Tutuka ash cores was low and varied between 0.6-1.1 mass % for 1-year-old ash cores to around 0.6-0.8 mass % for 8-year-old ash cores. Sodium levels were higher in 1-year-old ash cores compared to 8 year and 20-year-old ashcores. Observed trends indicate that quick weathering of the ash (within a year) leached out Na+ from the ash dump. No evidence of Na+ encapsulation even though the ash dump was brine irrigated. Thus the dry disposal ash placement method does not result in a sustainable salt sink for Na-containing species over time. The total content of each of the elements in 1 year and 20-year-old ash cores was normalised with their total content in fresh ash from same power station to show enrichment and depletion factor. Major elements such as K+, Mn showed enrichment in 1-year-old ash cores whereas Al, Si, Na+, Ti, Ca, Mg, S and Fe showed depletion due to over time erosion. Trace elements such as Cr, Sr, P, Ba, Pb, V and Zn showed enrichment but Ni, Y, Zr showed depletion attributed to over time erosion. In 20-year-old ash cores, major elements such as Al, Na+ and Mn showed enrichment while Si, K+, Fe, Mg and Ca showed depletion highlighting their mobility. Trends indicated intensive flushing of major soluble components such as buffering constituents (CaO) by percolating rain water. The 1-year-old and 20-year-old coal ash cores showed a lower pH and greater loss/depletion of the soluble buffering constituents than the 2-week-old placed ash, indicating significant chemical weathering within a year. Based&nbsp / on ANC results the leaching behaviours of Ca, Mg, Na+, K+, Se, Cr, and Sr were found to be controlled by the pH of the leachant indicating high mobility of major soluble species in the ash cores when in contact with slightly acid rain water. Other investigated toxic metals such as As, Mo and Pb showed amphoteric behaviour with respect to the pH of the leachant. Chemical alterations and formation of transient minor secondary mineral phases was found to have a significant effect on the acid susceptibility and depletion pattern of chemical species in the core ash samples when compared to fresh ash. These ANC results correlated well with the data generated from the sequential extraction scheme. Based on sequential extraction results elements, showed noticeable mobility in the water soluble, exchangeable and carbonate fractions due to adsorption and desorption caused by variations in the pore water pH. In contrast, slight mobility of elements in the Fe and Mn, and residual fractions of dry disposed fly ashes are attributed to the co-precipitation and dissolution of minor amount of less soluble secondary phase overtime. The 1-year-old dry disposed ash cores were the least weathered among the 3 drilled ash cores. Therefore low concentration of toxic metals in older ash cores were ascribed to extensive weathering with slower release from residual mineral phases over time. Elements were found to associate with different mineral phases depending on the age or depth of the core samples showing greater heterogeneity in dispersion. For instance the average amount of total calcium in different mineral associations of 1-year-old ash cores is as follows / water soluble (10.2 %), exchangeable (37.04 %), carbonate (37.9 %), Fe and Mn (7.1 %) and residual (2.97 %). The amount of total Na+ in different mineral phases of 1-year-old ash cores followed this trend: water soluble (21 %), exchangeable (11.26 %), carbonate (2.6 %), Fe and Mn (4.7 %) and residual (53.9 %). The non-leachable portion of the total Na+ content (namely that contained in the residual fraction) in the 1-year-old ash core samples under conditions found in nature ranged between 5-91 %. This non-leachable portion of the Na+ showed the metastability of the mineral phases with which residual Na+ associates. Results showed older ash cores are enriched in toxic elements. Toxic elements such as As, B, Cr, Mo and Pb are enriched in the residual fraction of older ash cores. For instance As concentration in the residual fraction varied between 0.0003- 0.00043 mg kg-1 for 1-year-old ash cores to around 0.0003-0.0015 mg kg-1 for 20-year-old ash cores. This suggests that the older ash is enriched in toxic elements hence dust from the ash dump would be toxic to human health. The knowledge of mobility and ecotoxicological significance of coal fly ash is needed when considering its disposal or reuse in the environment. The mobility and ecotoxicology of inorganic metals in coal fly ash are determined by (i) mineralogical associations of inorganic species (ii) in-homogeneity in the ash dumps (iii) long and short term exposure to ingress CO2 and percolating rain water. Management issues such as inconsistent placement of ash in the dumps, poor choice of ash dump site, in-homogeneity in brine irrigation, no record of salt load put on the ash dumps and lack of proper monitoring requires improvement. The thesis provides justification for the use of the modified sequential extraction scheme as a predictive tool and could be employed in a similar research work. This thesis also proved that the dry ash disposal method was not environmental friendly in terms of overall leaching potential after significant chemical weathering. Moreover the study proved that the practice of brine co-disposal or irrigation on ash dumps is not sustainable as the ash dump did not act as a salt sink.</p>

The current study therefore aims to provide a comprehensive characterisation of weathered dry disposed ash cores, to reveal mobility patterns of chemical species as a function of depth and age of ash, with a view to assessing the potential environmental impacts. Fifty-nine samples were taken from 3 drilled cores obtained respectively from the 1 year, 8 year and 20-year-old sections of sequentially dumped, weathered, dry disposed ash in an ash dump site at Tutuka - a South African coal burning power station.

Philosophiae Doctor - PhD / The management and disposal of huge volumes of coal combustion by products such as fly ash has constituted a major challenge to the environment. In most cases due to the inadequate alternative use of coal fly ash, the discarded waste is stored in holding ponds, slag heaps, or stock piled in ash dumps. This practice has raised concerns on the prospect of inorganic metals release to the surface and groundwater in the vicinity of the ash dump. Acceptable scientific studies are lacking to determine the best ash disposal practices. Moreover, knowledge about the mobility patterns of inorganic species as a function of mineralogical association or pH susceptibility of the dry disposed ash dump under natural weathering conditions are scarce in the literature. Fundamental understanding of chemical interactions of dry disposed ash with ingressed CO2 from atmosphere, percolating rain water and brine irrigation within ash disposal sites were seen as key areas requiring investigation. The mineralogical association of inorganic species in the dry disposed ash cores can be identified and quantified. This would provide a basis for understanding of chemical weathering, mineralogical transformations or mobility patterns of these inorganic species in the dry ash disposal scenario. The current study therefore aims to provide a comprehensive characterisation of weathered dry disposed ash cores, to reveal mobility patterns of chemical species as a function of depth and age of ash, with a view to assessing the potential environmental impacts. Fifty-nine samples were taken from 3 drilled cores obtained respectively from the 1 year, 8 year and 20-year-old sections of sequentially dumped, weathered, dry disposed ash in an ash dump site at Tutuka - a South African coal burning power station. The core samples were characterized using standard analytical procedures viz: X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) techniques, Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) and Acid neutralisation capacity (ANC) test. A modified sequential extraction (SE) method was used in this study. The chemical partitioning, mobility and weathering patterns in 1 year, 8 year and 20-year-old sections of the ash dump were respectively investigated using this modified sequential extraction scheme. The sequence of the extractions was as follows: (1) water soluble, (2) exchangeable, (3) carbonate, (4) iron and manganese and (5) residual. The results obtained from the 5 steps sequential extraction scheme were validated with the total metal content of the original sample using mass balance method. The distribution of major and trace elements in the different liquid fractions obtained after each step of sequential extraction of the 59 drilled core samples was determined by inductively coupled plasma mass spectrometry (ICPMS). The data generated for various ash core samples were explored for the systematic analysis of mineralogical transformation and change in ash chemistry with ageing of the ash. Furthermore, the data was analyzed to reveal the impact of ingressed CO2 from atmosphere, infiltrating rain water and brine irrigation on the chemistry of ash core samples. Major mineral phases in original ash core samples prior to extraction are quartz (SiO2) and mullite (Al2O3·2SiO2). Other minor mineral phases identified were hematite (Fe2O3), calcite (CaCO3), lime (CaO), anorthite (CaAl2Si2O8), mica (Ca (Mg, Al)3 (Al3Si) O10 (OH)2), and enstatite (Mg2Si2O6). X-ray diffraction results show significant loss of crystallinity in the older ash cores. The presence of minor phases of calcite and mica in dry disposed ash cores are attributed to reduction in the pore water pH due to hydration, carbonation and pozzolanic reactions. The X-ray diffraction technique was unable to detect Fe-oxyhydroxide phase and morealuminosilicate phases in ash core samples due to their low abundance and amorphous character. X-ray fluorescence results of the original ash core samples showed the presence of major oxides, such as SiO2, Al2O3, Fe2O3, while CaO, K2O, TiO2, Na2O, MnO, MgO, P2O5, and SO3 occur in minor concentrations. The ratio of SiO2/Al2O3 classified the original core samples prior to extraction as a silico-aluminate class F fly ash. The ternary plot of major elements in 1-year-old ash core samples was both sialic and ferrocalsialic but 8 year and 20-year-old ash core samples were sialic in chemical composition. It is noteworthy that the mass % of SiO2 varies through the depth of the core with an increase of nearly 3 %, to 58 mass % of SiO2 at a depth of 6 m in the 1-year-old core whereas in the case of the 8-year-old core a 2 % increase of SiO2 to a level of 57.5 mass % can be observed at levels between 4-8 m, showing dissolution of major components in the matrix of older ash cores.. The Na2O content of the Tutuka ash cores was low and varied between 0.6-1.1 mass % for 1-year-old ash cores to around 0.6-0.8 mass % for 8-year-old ash cores. Sodium levels were higher in 1-year-old ash cores compared to 8 year and 20-year-old ashcores. Observed trends indicate that quick weathering of the ash (within a year) leached out Na+ from the ash dump. No evidence of Na+ encapsulation even though the ash dump was brine irrigated. Thus the dry disposal ash placement method does not result in a sustainable salt sink for Na-containing species over time. The total content of each of the elements in 1 year and 20-year-old ash cores was normalised with their total content in fresh ash from same power station to show enrichment and depletion factor. Major elements such as K+, Mn showed enrichment in 1-year-old ash cores whereas Al, Si, Na+, Ti, Ca, Mg, S and Fe showed depletion due to over time erosion. Trace elements such as Cr, Sr, P, Ba, Pb, V and Zn showed enrichment but Ni, Y, Zr showed depletion attributed to over time erosion. In 20-year-old ash cores, major elements such as Al, Na+ and Mn showed enrichment while Si, K+, Fe, Mg and Ca showed depletion highlighting their mobility. Trends indicated intensive flushing of major soluble components such as buffering constituents (CaO) by percolating rain water. The 1-year-old and 20-year-old coal ash cores showed a lower pH and greater loss/depletion of the soluble buffering constituents than the 2-week-old placed ash, indicating significant chemical weathering within a year. Based on ANC results the leaching behaviours of Ca, Mg, Na+, K+, Se, Cr, and Sr were found to be controlled by the pH of the leachant indicating high mobility of major soluble species in the ash cores when in contact with slightly acid rain water. Other investigated toxic metals such as As, Mo and Pb showed amphoteric behaviour with respect to the pH of the leachant. Chemical alterations and formation of transient minor secondary mineral phases was found to have a significant effect on the acid susceptibility and depletion pattern of chemical species in the core ash samples when compared to fresh ash. These ANC results correlated well with the data generated from the sequential extraction scheme. Based on sequential extraction results elements, showed noticeable mobility in the water soluble, exchangeable and carbonate fractions due to adsorption and desorption caused by variations in the pore water pH. In contrast, slight mobility of elements in the Fe and Mn, and residual fractions of dry disposed fly ashes are attributed to the co-precipitation and dissolution of minor amount of less soluble secondary phase overtime. The 1-year-old dry disposed ash cores were the least weathered among the 3 drilled ash cores. Therefore low concentration of toxic metals in older ash cores were ascribed to extensive weathering with slower release from residual mineral phases over time. Elements were found to associate with different mineral phases depending on the age or depth of the core samples showing greater heterogeneity in dispersion. For instance the average amount of total calcium in different mineral associations of 1-year-old ash cores is as follows; water soluble (10.2 %), exchangeable (37.04 %), carbonate (37.9 %), Fe and Mn (7.1 %) and residual (2.97 %). The amount of total Na+ in different mineral phases of 1-year-old ash cores followed this trend: water soluble (21 %), exchangeable (11.26 %), carbonate (2.6 %), Fe and Mn (4.7 %) and residual (53.9 %). The non-leachable portion of the total Na+ content (namely that contained in the residual fraction) in the 1-year-old ash core samples under conditions found in nature ranged between 5-91 %. This non-leachable portion of the Na+ showed the metastability of the mineral phases with which residual Na+ associates. Results showed older ash cores are enriched in toxic elements. Toxic elements such as As, B, Cr, Mo and Pb are enriched in the residual fraction of older ash cores. For instance As concentration in the residual fraction varied between 0.0003- 0.00043 mg kg-1 for 1-year-old ash cores to around 0.0003-0.0015 mg kg-1 for 20-year-old ash cores. This suggests that the older ash is enriched in toxic elements hence dust from the ash dump would be toxic to human health. The knowledge of mobility and ecotoxicological significance of coal fly ash is needed when considering its disposal or reuse in the environment. The mobility and ecotoxicology of inorganic metals in coal fly ash are determined by (i) mineralogical associations of inorganic species (ii) in-homogeneity in the ash dumps (iii) long and short term exposure to ingress CO2 and percolating rain water. Management issues such as inconsistent placement of ash in the dumps, poor choice of ash dump site, in-homogeneity in brine irrigation, no record of salt load put on the ash dumps and lack of proper monitoring requires improvement. The thesis provides justification for the use of the modified sequential extraction scheme as a predictive tool and could be employed in a similar research work. This thesis also proved that the dry ash disposal method was not environmental friendly in terms of overall leaching potential after significant chemical weathering. Moreover the study proved that the practice of brine co-disposal or irrigation on ash dumps is not sustainable as the ash dump did not act as a salt sink. / South Africa