This research was designed to investigate the hydration reaction of fly ash when exposed to water. The effects that calcium nitrate and calcium formate have on the hydration reactions were also examined.

Vineyards in the Eastern United States are often prone to excessive vegetative growth. In order to suppress excessive vine vigor, many viticulturists have employed cover cropping strategies. Cover crops provide a myriad of agronomic benefits, however they are known to compete with the vine for water and nutrients. Due to the widespread use of cover crops in Eastern vineyards, many vineyards experience nitrogen (N) deficiencies in both the vegetative vine tissue and yeast assimilable nitrogen (YAN) in the juice. Soil applications of calcium nitrate and foliar applications of urea were assessed as a means of vineyard N amelioration at cover cropped sites comprised of Petit Manseng and Sauvignon blanc (Vitis vinifera L.). Perennial White and Crimson clover cover crops and foliar urea applications were also used in a Vidal blanc (Vitis spp.) vineyard. Treatments were imposed in the Sauvignon blanc vineyard for five years. The Petit Manseng and Vidal blanc vineyards were subjected to treatments for two years. Soil-applied N at bloom was most effective at increasing leaf petiole N at véraison, season-long chlorophyll content index (CCI), vine capacity and fruit yield. Fruit yield was increased due to more berries per cluster and greater berry weights. Increased rates of soil-applied N decreased the fruit weight:pruning weight ratio. Clover cover crops offered little to no benefit as a N source in the two-year period of evaluation. None of the N management schemes negatively impacted canopy density, fruit zone light interception, or botrytis bunch rot incidence. The combination of both a soil-applied and foliar-applied N fertilizer may be the most effective means to increase both vine capacity and YAN in vineyards where vineyard floor cover crops are compromising vine N status. / Master of Science

To combat excessive vine vigor, many vintners have employed intensive cover cropping techniques. While cover crops provide a multitude of benefits to the farming system, they can compete for nutrients and water. The seemingly ubiquitous adoption of cover crops in the Eastern United States has led to vines and grape musts which are deficient in nitrogen (N). A must that is deficient in yeast assimilable nitrogen (YAN) can lead to the production of off aromas and stuck or sluggish fermentations. It has also been suggested that musts with limited amino nitrogen sources can result in wines with less fruity aromas than those with a higher starting amino acid content. Varying rates of calcium nitrate were applied to the soil at bloom and foliar urea was sprayed at a Sauvignon blanc and Petit Manseng (Vitis vinifera L.) vineyard. Perennial White and Crimson clover as well as foliar urea applications at véraison were utilized at a Vidal blanc (Vitis spp.) site. Foliar urea was effective at significantly increasing YANs in all experiments with some year to year variation in efficacy. Foliar urea applications slightly favored the production of ammonia over primary amino nitrogen. While most of the measured amino acids in fruit increased in concentration with the application of either soil or foliar N, foliar applications were more effective at increasing fruit amino acids. Of the amino acids measured, arginine and glutamine were the most increased by foliar urea applications, whereas proline was relatively unaffected. The use of clover as a perennial under-vine cover crop did not increase berry YAN. The application of foliar urea sprays may present an effective means by which vintners can easily increase must YANs and amino acid contents. / Master of Science in Life Sciences

Objetivou-se avaliar o uso de nitrato de cálcio (NC) na alimentação de ruminantes com vistas à mitigação da emissão de metano. Foram utilizadas quatro fêmeas de cada subespécie, Bos taurus taurus (Holandês) e vBos taurus indicus (Nelore), com peso médio inicial de 909,0 kg ± 72,0 e 387,0 kg ± 25,5, respectivamente, alimentadas com diferentes níveis de nitrato de cálcio na dieta (0%, 1%, 2% e 3%), sendo utilizado delineamento quadrado latino 4X4 replicado. O experimento teve duração de 4 períodos de 28 dias cada. Foram avaliados, a ingestão, excreção e digestibilidade de nutrientes, por meio de marcador externo dióxido de titânio, o comportamento ingestivo, com monitoramento visual por 24 horas, parâmetros sanguíneos, dinâmica ruminal, com esvaziamento total do rumen, contagem de protozoários, fermentação ruminal, pela técnica ex-situ, parâmetros urinários e balanço de nitrogênio, com coleta manual de urina tipo spot, e a biodigestão dos dejetos, por biodigestores do tipo batelada. Os taurinos apresentaram valores superiores para CMS, ingestão e digestibilidade de nutrientes e excreção de MS, PB, FDN, FDA, N, MO e EB, e inferiores para CMS em relação ao PV e PM. Os zebuínos apresentaram maiores taxas de ingestão, ruminação e mastigação de MS e FDN em min/kg, tendo valores inferiores para as mesmas taxas em kg/min. A genética e a dose de nitrato influenciaram as variáveis séricas, porém sem valores fora da normalidade. Quanto à dinâmica ruminal, os taurinos apresentaram valores absolutos superiores, e valores em relação ao PV e PM inferiores. Os zebuínos apresentaram maiores pH médio e mínimo e menos tempo de pH abaixo de 6,2, e maior contagem de protozoários. As concentrações de N-NH3, volume e produção de CH4 foram maiores para os zebuínos. Os taurinos apresentaram valores mais elevados para N microbiano (g/dia) e balanço de N retido (g/kg N ingerido), e menores valores para balanço de N nas fezes (g/kgN ingerido) e N microbiano (mg/kgPM.d-1). O aumento no nível de NC na dieta aumentou a digestibilidade de EE e ENN, tempo médio ruminando e taxa de mastigação de MS e FDN (min/kg), e diminuiu o CMS em relação ao PV e PM e excreção de MS, EE, ENN, MO e EB. A taxa de ingestão de MS e FDN (kg/min), a concentração de creatinina na urina (mg/kgPV), o tempo total comendo e balanço de nitrogênio amoniacal o rúmen sofreram efeito quadrático com a adição de NC na dieta. A porcentagem de FDN, PB e EE nos afluentes dos bidigestores sofreram influência da dose de nitrato na alimentação das vacas. Os biodigestores contendo os dejetos de taurinos tiveram os afluentes com maiores valores de FDN e FDA e menor teor de sólidos totais (ST), com menor volume de biogás e CH4 e menor relação de CH4/quantidade de fezes. Os taurinos apresentaram melhor aproveitamento do alimento, produzindo menos CH4, com menor rendimento verdadeiro de produção de metano nos biodigestores. A adição de NC afetou o consumo, digestibilidade e utilização do nitrogênio porém, sem afetar a produção de CH4 nem a eficiencia dos biodigestores. / The aim of the present study was evaluate the use of calcium nitrate in the feeding of ruminants to mitigate of methane. Four females cattle from each subspecies of cattle, Bos taurus taurus (Holstein) and Bos taurus indicus (Nellore), with initial average weight of 909,0 kg ± 72,0 e 387,0 kg ± 25,5, respectively, were used, and they were fed with distinct levels of calcium nitrate in the diet (0%, 1%, 2% e 3%) at four periods of 28 days each. Experimental design was composed by a replicated Latin square 4X4. Were avaluated: ingestion, excretion and digestibility of nutrients, by means of external marker titanium dioxide; the observation of behavior parameters during 24 hours; serum analysis; rumen content collection, aiming assessment of fermentation; protozoa count; ruminal fermentation by the ex-situ technique; manual urine collection for measurement of urinary compounds and nitrogen balance; and the anaerobic digestion of feces using batch digesters. Holsteins presented higher values for the DMI, ingestion and digestibility of the nutrients and excretion of DM, CP, NDF, ADF, N, OM e GE, and lower values for DMI at body weight (BW) and metabolic weight (MW) basis. Nellore cattle showed higher rates of ingestion, rumination and chewing of DM e NDF min/kg, having lower values for the same rates in kg/min. Serum variables were influenced by genetics and nitrate levels, but without values beyond normality. As rumen dynamics, Holsteins presented superior absolute values and inferior values when these parameters were calculated in BW and MW basis. The zebu cattle presented medium and minimum pH larger and less time pH below 6.2, having larger count for protozoa count. Nellore had higher concentrations for NH3, CH4 and production of CH4. Holstein presented higher values for microbial N (g/day) and N retained balance (g/kg N ingested) and lower values for N balance in feces (g/kgN ingested) and microbial N (mg/kgMW.d-1). The increase in the level of CN in the diet increased linearly the digestibility of EE and NNE, average time ruminating, chewing rate for DM and NDF (min/kg), and decreased the DMI in BW and MW basis and the excretion of DM, EE, NNE, OM and GE. The intake rate of DM and NDF kg/min, creatinine in urine (mg/kgBW), the total time eating and NH3 balance showed quadratic effect by increasing the addition of CN in the diet. The levels of nitrate on animal feed influenced the percentage of NDF, CP and EE in the batch digesters afluents. The biodigestors containing the taurine feces presented the highest values of NDF/ ADF affluent and lowest values for total solids (TS), lower volume of biogas and CH4 and lower ratio of CH4/amount of feces. Taurines presented better use of the feed, producing lesser CH4, and lower ultimate methane yield at batch digesters. The CN levels affected the intake, digestibility and nitrogen metabolism, however without affecting the production of CH4 or the batch digester efficiency.

Submitted by Neusa Fagundes (neusa.fagundes@unioeste.br) on 2017-08-29T13:39:19Z No. of bitstreams: 2 Ederson_Bugatti2016.pdf: 1227431 bytes, checksum: ecc408ae972a5ec71f17bd55f9cbb474 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-08-29T13:39:19Z (GMT). No. of bitstreams: 2 Ederson_Bugatti2016.pdf: 1227431 bytes, checksum: ecc408ae972a5ec71f17bd55f9cbb474 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-10-03 / The generation of hatchery waste has been following the significant increase in poultry activity in Brazil. Due to this waste being aggressive to handle and of difficult recovery of nutrients, especially calcium, chemical treatments may be the solution. This study aimed to assess the feasibility of calcium recovery contained in hatchery waste through reaction with phosphoric and nitric acids in different concentrations. Besides the yield in calcium solubilization, pH and electric conductivity of the liquid fraction from the reaction were determined, as well as the yield of final product derived from lyophilization, probably dicalcium phosphate and calcium nitrate, both products of agronomic, nutritional, and commercial values. The most interesting results considering the yield of calcium solubilization were obtained using phosphoric acid in higher concentrations, i.e. 100 and 90%, namely 84.8 and 78.8%. For the nitric acid, the highest yields were obtained at concentrations of 100, 90, and 80%, with average scores of 72.2, 71.6, and 68.5% respectively. The yield of salt from the reaction with the acid was 2.5 and 2.4 tons of dicalcium phosphate per ton of waste hatchery (dry weight) and 2.0, 1.8 and 1.7 tons of calcium nitrate by tons of hatchery waste (dry mass). It was concluded that phosphoric acid at 100% was more efficient in the recovery of calcium contained in the hatchery waste, although nitric acid promotes further degradation of other components of hatchery waste, which generates a liquid fraction with higher electrical conductivity. / A geração de resíduos de incubatório acompanha o expressivo aumento da atividade avícola do Brasil. Em função de ser um resíduo agressivo ao manejo e de difícil recuperação dos nutrientes nele contido, principalmente o cálcio, tratamentos químicos podem ser a solução. Objetivou-se avaliar a viabilidade da recuperação do cálcio contido nos resíduos de incubatório por meio da reação com os ácidos fosfórico e nítrico em diferentes concentrações. Além do rendimento na solubilização do cálcio, determinou-se o pH e a condutividade elétrica da fração líquida provenientes das reações e o rendimento do produto final derivado da liofilização desta fração, provavelmente o fosfato bicálcico e o nitrato de cálcio, ambos produtos comerciais com valores agronômico e nutricional. Os resultados mais interessantes, considerando o rendimento da solubilização do cálcio, foram obtidos com o uso do ácido fosfórico nas maiores concentrações, ou seja, 100 e 90%, a saber, 84,8 e 78,8%. Para o ácido nítrico, os maiores rendimentos foram obtidos nas concentrações de 100, 90 e 80%, com resultados médios de 72,2, 71,6 e 68,5%, respectivamente. O rendimento do sal proveniente da reação com os ácidos foi de 2,5 e 2,4 toneladas de fosfato bicálcico por tonelada de resíduo de incubatório (massa seca) e 2,0, 1,8 e 1,7 toneladas de nitrato de cálcio por tonelada de resíduo de incubatório (massa seca). Concluiu-se que o ácido fosfórico na concentração de 100% foi mais eficiente na recuperação do cálcio contido nos resíduos de incubatório, embora o ácido nítrico promova uma maior degradação de outros componentes do resíduo de incubatório, o que gera uma fração líquida com maior condutividade elétrica.

Due to strict placement time and strength constraints during the construction of concrete pavement repair slabs, accelerators must be incorporated into the mixture design. Since the most common accelerator, calcium chloride, promotes corrosion of concrete reinforcement, a calcium nitrate-based accelerator was studied as an alternative. To replicate mixtures used in the field, commercial accelerators commonly used in concrete pavement repair slabs were used in the current study. Crack risk of different mixtures was assessed using modeling and cracking frame testing. HIPERPAV modeling was conducted using several measured mixture properties; namely, concrete mechanical properties, strength-based and heat of hydration-based activation energies, hydration parameters using calorimetric studies, and adiabatic temperature rise profiles. Autogenous shrinkage was also measured to assess the effect of moisture consumption on concrete volume contraction. The findings of the current study indicate that the cracking risk associated with calcium nitrate-based accelerator matches the performance of a calcium-chloride based accelerator when placement is conducted during nighttime hours.

Objetivou-se avaliar o uso de nitrato de cálcio (NC) na alimentação de ruminantes com vistas à mitigação da emissão de metano. Foram utilizadas quatro fêmeas de cada subespécie, Bos taurus taurus (Holandês) e vBos taurus indicus (Nelore), com peso médio inicial de 909,0 kg ± 72,0 e 387,0 kg ± 25,5, respectivamente, alimentadas com diferentes níveis de nitrato de cálcio na dieta (0%, 1%, 2% e 3%), sendo utilizado delineamento quadrado latino 4X4 replicado. O experimento teve duração de 4 períodos de 28 dias cada. Foram avaliados, a ingestão, excreção e digestibilidade de nutrientes, por meio de marcador externo dióxido de titânio, o comportamento ingestivo, com monitoramento visual por 24 horas, parâmetros sanguíneos, dinâmica ruminal, com esvaziamento total do rumen, contagem de protozoários, fermentação ruminal, pela técnica ex-situ, parâmetros urinários e balanço de nitrogênio, com coleta manual de urina tipo spot, e a biodigestão dos dejetos, por biodigestores do tipo batelada. Os taurinos apresentaram valores superiores para CMS, ingestão e digestibilidade de nutrientes e excreção de MS, PB, FDN, FDA, N, MO e EB, e inferiores para CMS em relação ao PV e PM. Os zebuínos apresentaram maiores taxas de ingestão, ruminação e mastigação de MS e FDN em min/kg, tendo valores inferiores para as mesmas taxas em kg/min. A genética e a dose de nitrato influenciaram as variáveis séricas, porém sem valores fora da normalidade. Quanto à dinâmica ruminal, os taurinos apresentaram valores absolutos superiores, e valores em relação ao PV e PM inferiores. Os zebuínos apresentaram maiores pH médio e mínimo e menos tempo de pH abaixo de 6,2, e maior contagem de protozoários. As concentrações de N-NH3, volume e produção de CH4 foram maiores para os zebuínos. Os taurinos apresentaram valores mais elevados para N microbiano (g/dia) e balanço de N retido (g/kg N ingerido), e menores valores para balanço de N nas fezes (g/kgN ingerido) e N microbiano (mg/kgPM.d-1). O aumento no nível de NC na dieta aumentou a digestibilidade de EE e ENN, tempo médio ruminando e taxa de mastigação de MS e FDN (min/kg), e diminuiu o CMS em relação ao PV e PM e excreção de MS, EE, ENN, MO e EB. A taxa de ingestão de MS e FDN (kg/min), a concentração de creatinina na urina (mg/kgPV), o tempo total comendo e balanço de nitrogênio amoniacal o rúmen sofreram efeito quadrático com a adição de NC na dieta. A porcentagem de FDN, PB e EE nos afluentes dos bidigestores sofreram influência da dose de nitrato na alimentação das vacas. Os biodigestores contendo os dejetos de taurinos tiveram os afluentes com maiores valores de FDN e FDA e menor teor de sólidos totais (ST), com menor volume de biogás e CH4 e menor relação de CH4/quantidade de fezes. Os taurinos apresentaram melhor aproveitamento do alimento, produzindo menos CH4, com menor rendimento verdadeiro de produção de metano nos biodigestores. A adição de NC afetou o consumo, digestibilidade e utilização do nitrogênio porém, sem afetar a produção de CH4 nem a eficiencia dos biodigestores. / The aim of the present study was evaluate the use of calcium nitrate in the feeding of ruminants to mitigate of methane. Four females cattle from each subspecies of cattle, Bos taurus taurus (Holstein) and Bos taurus indicus (Nellore), with initial average weight of 909,0 kg ± 72,0 e 387,0 kg ± 25,5, respectively, were used, and they were fed with distinct levels of calcium nitrate in the diet (0%, 1%, 2% e 3%) at four periods of 28 days each. Experimental design was composed by a replicated Latin square 4X4. Were avaluated: ingestion, excretion and digestibility of nutrients, by means of external marker titanium dioxide; the observation of behavior parameters during 24 hours; serum analysis; rumen content collection, aiming assessment of fermentation; protozoa count; ruminal fermentation by the ex-situ technique; manual urine collection for measurement of urinary compounds and nitrogen balance; and the anaerobic digestion of feces using batch digesters. Holsteins presented higher values for the DMI, ingestion and digestibility of the nutrients and excretion of DM, CP, NDF, ADF, N, OM e GE, and lower values for DMI at body weight (BW) and metabolic weight (MW) basis. Nellore cattle showed higher rates of ingestion, rumination and chewing of DM e NDF min/kg, having lower values for the same rates in kg/min. Serum variables were influenced by genetics and nitrate levels, but without values beyond normality. As rumen dynamics, Holsteins presented superior absolute values and inferior values when these parameters were calculated in BW and MW basis. The zebu cattle presented medium and minimum pH larger and less time pH below 6.2, having larger count for protozoa count. Nellore had higher concentrations for NH3, CH4 and production of CH4. Holstein presented higher values for microbial N (g/day) and N retained balance (g/kg N ingested) and lower values for N balance in feces (g/kgN ingested) and microbial N (mg/kgMW.d-1). The increase in the level of CN in the diet increased linearly the digestibility of EE and NNE, average time ruminating, chewing rate for DM and NDF (min/kg), and decreased the DMI in BW and MW basis and the excretion of DM, EE, NNE, OM and GE. The intake rate of DM and NDF kg/min, creatinine in urine (mg/kgBW), the total time eating and NH3 balance showed quadratic effect by increasing the addition of CN in the diet. The levels of nitrate on animal feed influenced the percentage of NDF, CP and EE in the batch digesters afluents. The biodigestors containing the taurine feces presented the highest values of NDF/ ADF affluent and lowest values for total solids (TS), lower volume of biogas and CH4 and lower ratio of CH4/amount of feces. Taurines presented better use of the feed, producing lesser CH4, and lower ultimate methane yield at batch digesters. The CN levels affected the intake, digestibility and nitrogen metabolism, however without affecting the production of CH4 or the batch digester efficiency.

Allium sativum and Tulbaghia violacea are some of the most important medicinal plants used by South African traditional healers for the treatment of flu, fever, cold, tuberculosis, asthma and many more diseases. However, growth, yield and quality are constrained by excessive and under fertilization. This study was carried out to determine, firstly, the effect of N source (ammonium sulphate and calcium nitrate) on yield and quality of A. sativum and T. violacea plants. Secondly, to determine the best season for harvesting T. violacea and lastly, to determine the antifungal effects of A. sativum and T. violacea plant extracts against plant pathogens Altenaria solani and Sclerotium rolfsii. Both plants were treated with both N sources applied as topdressing treatments at a total of 0, 50, 100, 150 and 200 kg.ha-1, divided into three applications at three week (A. sativum) and three month (T. violacea) intervals. A. sativum plants were sampled at 54, 82, 112, 140 and 175 days after planting (DAP) while, T. violacea plants were sampled monthly for ten months. Parameters recorded were growth analysis, yield and bioactivity for both plant species. Both nitrogen sources improved plant growth and yield of A. sativum and T. violacea plants. Calcium nitrate at 150 kg•ha-1 and ammonium sulphate at 200 kg•ha-1 produced the highest at 24 t•ha-1 and 27 t•ha-1, respectively. Ammonium sulphate improved bioactivity of leaves with the highest bioactivity recorded at 82 and 112 DAP. Yield obtained from the autumn harvest was not affected by N source. Ammonium sulphate and calcium nitrate at 200 kg•ha-1 produced the highest yields of 23.6 t•ha-1 and 23.5 t•ha-1, respectively. In contrast, yield obtained from the winter harvest was affected by N source at 200 kg•ha-1, with significantly better yield of 30.8 t•ha-1 with calcium nitrate compared to 27.4 t•ha-1 with ammonium sulphate. Crude extracts of T. violacea bulbs that were treated with ammonium sulphate significantly inhibited the growth of plant pathogenic fungi, whereas extracts from plants treated with calcium nitrate showed low bioactivity. Extracts from plants grown with ammonium sulphate at 100 kg•ha-1 were more effective in controlling growth of plant pathogens when compared to other N levels. The minimum inhibitory concentration (MIC) effects of A. sativum against S. rolfsii and A. solani were at 0.01 mg•mL-1. The MIC of T. violacea extracts against A. solani was at 0.006 mg•mL<Sup>-1. The MIC of T. violacea extracts were better than previously reported in literature. Therefore, A. sativum and T. violacea plant extracts can be used as fungicides against S. rolfsii and A. solani diseases for crops such as tomato and potato. / Dissertation (MInstAgrar)--University of Pretoria, 2010. / Plant Production and Soil Science / unrestricted

Made available in DSpace on 2016-06-02T20:34:28Z (GMT). No. of bitstreams: 1 3929.pdf: 7149120 bytes, checksum: e2177db6aa73e14034501caea52c53c8 (MD5) Previous issue date: 2010-12-20 / Universidade Federal de Sao Carlos / Ibirité Reservoir (Ibirité/Sarzedo, MG) receives untreated effluents and raw sewage from the city of Ibirité and surroundings, which are the main cause of the eutrophication of this ecosystem. Past studies have shown that sediment is a significant internal source of nutrients (ammonium and orthophosphate ions) to the water column. Within this context, the main objective of this study was to perform laboratory experiments (microcosms) using calcium nitrate and Phoslock as sediment remediation technologies to immobilize orthophosphate ions. Total incubation time was 145 days for the experiments with nitrate and 41 days using Phoslock . The results of the experiments involving the addition of calcium nitrate showed a reduction in the concentration of orthophosphate in the water column (75%) and interstitial water (89%). After 145 days the sediment was significantly oxidized and there was almost complete abatement of acid volatile sulfide in the sediments, leading to a significant increase in sulfate concentrations. The system s nitrogen mass balance revealed the occurrence of an intense process of denitrification. The ecotoxicological assays initially showed that the high concentrations of nitrate (up to 2,300 mg L-1 and 270 mg L-1 in the sediment s interstitial waters, repectively) were responsible for the mortality of test organisms. However, at the end of the experiment, sediment toxicity disappeared completely and there was a significant reduction in the water s EC50 values at 48h. The results of the assays involving the addition of Phoslock showed an 82% reduction in the concentration of orthophosphate in the water column immediately after application of the product and a 64% reduction in interstitial water after 41 days of treatment. The application of the Phoslock suspension increased water column turbidity (150 NTU), which, however, declined by 75% just 6 hours later. The concentration of dissolved oxygen in the water column increased significantly 360 hours into the experiment. The application of Phoslock caused a significant increase in the concentration of dissolved lanthanum in the water column. At the time of application (t = 0), the concentration of La in the water column was 1.64 mg L-1; however, at the end of the assay, the concentration of this element had dropped to less than 0.05 mg L-1. The ecotoxicological tests showed that at t = 0 the application of Phoslock caused mortality of the test organisms in the water column samples, which may have been due to an increase in turbidity and La concentration during this period. Consequently, at the end of these assays, the toxicity was completely eliminated. Considering the general characteristics of the assays performed here, it is postulated that both the technologies studied showed good application potential, i.e., the results obtained indicated that both technologies were efficient in removing P from the water. However, the chances of success of these treatments in the long run will depend (among other factors) on the abatement of the external sources and on the long-term maintenance of such abatement. Since both the technologies investigated appeared to perform similarly in this respect, the use of Phoslock to remediate the eutrophic sediments of the Ibirité reservoir may be more favorable than that of nitrate, if one considers the cost estimates presented in this work from the standpoint of the approximations or forecasts employed here. / A Represa Ibirité (Ibirité/Sarzedo, MG) recebe aportes de efluentes tratados e esgoto urbano não tratado da cidade de Ibirité e adjacências, o qual é a principal causa da eutrofização desse ecossistema. Além disso, estudos pretéritos indicaram que o fluxo interno de nutrientes (principalmente amônio e ortofosfato) dos sedimentos para a coluna de água também são significativos. Neste contexto, o objetivo principal deste estudo foi a realização de experimentos em laboratório (microcosmos) utilizando nitrato de cálcio e Phoslock como tecnologias de remediação dos sedimentos, visando a imobilização dos íons ortofosfato. Os períodos totais de incubação foram de 145 dias para os experimentos com adição de nitrato e de 41 dias para os ensaios com Phoslock . Os resultados obtidos nos ensaios com aplicação de nitrato de cálcio mostraram que houve uma redução na concentração de ortofosfato na coluna de água (75%) e água intersticial (89%). Após 145 dias os sedimentos foram significativamente oxidados e houve abatimento quase total dos sulfetos presentes nos sedimentos, levando a um grande aumento nas concentrações de sulfato. O balanço de massas de nitrogênio no sistema evidenciou a ocorrência de um intenso processo de desnitrificação. Os ensaios ecotoxicológicos evidenciaram, inicialmente, que as altas concentrações de nitrato e nitrito (de até 2.300 mg L-1 e 270 mg L-1 nas águas intersticias dos sedimentos, respectivamente) foram responsáveis pela mortalidade dos organismos-teste, entretanto, ao final do experimento, a toxicidade dos sedimentos foi completamente abatida e houve uma redução significativa nos valores de CE50;48h nas águas. Os ensaios com aplicação de Phoslock mostraram que houve uma redução de 82% na concentração de ortofosfato na coluna de água imediatamente após a aplicação do produto e que, após 41 dias de tratamento, houve uma redução de 64% para a água intersticial. Devido à aplicação da suspensão de Phoslock houve um aumento nos valores de turbidez (150 NTU), mas apenas 6 horas após a adição esse valor foi reduzido em 75%. Após 360 horas de experimento, os valores de oxigênio dissolvido na coluna de água aumentaram significativamente. A aplicação de Phoslock causou um aumento na concentração de lantânio dissolvido na coluna de água. No momento da xii aplicação (t=0) a concentração de La na coluna de água foi de 1,64 mg L-1, no entanto, no final do experimento, a concentração deste analito foi inferior a 0,05 mg L-1. Os ensaios ecotoxicológicos evidenciaram que em t=0 a aplicação de Phoslock causou mortalidade dos organismos testados com amostras de coluna de água, fato que pode estar associado principalmente ao aumento da turbidez nesse período, mas também, devido à presença de lantânio nas águas. Ao final dos experimentos, a toxicidade foi completamente abatida. Considerando as características dos experimentos realizados neste trabalho, postula-se que ambas as tecnologias estudadas apresentaram bom potencial de aplicação, i.e., os resultados obtidos indicaram que ambas tais tecnologias foram eficazes na remoção e imobilização dos íons ortofosfato nas águas. No entanto, as chances de sucesso a longo prazo desses tratamentos dependem muito do abatimento das fontes externas e da manutenção deste abatimento. Como ambas as tecnologias estudadas parecem ter rendimento similar a este respeito, a aplicação de Phoslock para a remediação dos sedimentos da Represa Ibirité, pode ser favorecida em relação à adição de nitrato, se forem consideradas as estimativas de custos realizados neste trabalho, dentro das aproximações ou previsões aqui empregadas.

Made available in DSpace on 2016-06-02T19:31:43Z (GMT). No. of bitstreams: 1 2493.pdf: 1820155 bytes, checksum: c4fbdc0a3fdb7a9316ba5c6c6a6905c8 (MD5) Previous issue date: 2009-05-15 / Universidade Federal de Sao Carlos / The objective of the present dissertation was to make a toxicity assessment of the application of calcium nitrate solution as a remediation procedure for sediments of a eutrophic aquatic ecosystem. The study was carried out using microcosms with superficial sediments and water from sediment-water interface of the Ibirité Reservoir located in the metropolitan area of Belo Horizonte (Minas Gerais, SE Brazil). The experiment lasted 135 days and the following treatment or incubation periods were applied: t=0, t=5, t=10, t=25, t=50, t=85 and t=135 days. In each period, one controlmicrocosm and three treatment-microcosms were disassembled and, chemically and ecotoxicologically analyzed. The organisms Ceriodaphnia silvestrii and Vibrio fischeri (Microtox® System) were used for the acute toxicity assessment of the water from sediment-water interface and the pore water of sediments, whereas the organism Chironomus xanthus was used for the toxicity assessment of bulk sediment. The toxicity tests were run in parallel with chemical analyzes of dissolved inorganic nitrogen species (nitrate, nitrate and ammonium), sulfate, and metals in the interface sediment-water and interstitial water samples. Acid volatile sulfide (AVS), simultaneously extracted metal (SEM) and potentially bioavailable metals were analyzed in bulk sediment. The overall results indicate that nitrate whose concentration reached 1,200 mg N-NO3 - L-1 in sediment pore water samples from treatment-microcosms is the most probable compound causing toxicity to the tests organisms. For Chironomus xanthus sediments were deleterious to the exposed organisms in all microcosm run, except in the period of t= 135 days. For the experimental conditions of this work, the application of calcium nitrate as a remediation procedure for sediments from Ibirité Reservoir indicated to be inadequate from the ecotoxicological pint of view. / O presente trabalho visou à avaliação da toxicidade da aplicação de solução de nitrato de cálcio, como procedimento de intervenção para remediação de sedimentos de um ambiente aquático eutrofizado. O estudo foi realizado através de microcosmos com sedimento e água de interface sedimento-água da Represa Ibirité, situada na região metropolitana de Belo Horizonte (Minas Gerais, Brasil). Os experimentos tiveram a duração total de 135 dias, divididos nos tempos de tratamento ou incubação de: t=0, t=5; t=10; t=25; t=50; t=85 e t=135 dias. Em cada tempo de tratamento foram analisados um microcosmo-controle e três microcosmostratamento. Os organismos Ceriodaphnia silvestrii e Vibrio fischeri (Sistema Microtox®) foram utilizados para avaliação da toxicidade aguda das águas de interface sedimento-água e intersticial dos sedimentos, enquanto o organismo Chironomus xanthus para avaliação do sedimento integral. Em paralelo aos testes de toxicidade foram realizadas análises químicas da série nitrogenada (nitrato, nitrito e amônia), sulfato, e metais nas amostras de água de interface sedimento-água e intersticial dos sedimentos, sulfetos volatilizáveis por acidificação (SVA), metais extraídos simultaneamente (MES) e metais potencialmente biodisponíveis nos sedimentos. Os resultados mostraram que o nitrato, chegando a concentração superior a 1.200 mg N-NO3 - L-1 nas amostras de água intersticial dos sedimentos dos microcosmos-tratamentos, foi considerado o causador mais provável da toxicidade das amostras dos microcosmos-tratamento para os organismos-teste empregados. Para o organismo Chironomus xanthus, os sedimentos em tratamento foram deletérios aos organismos expostos em todos os tempos de incubação, exceto no tempo t=135 dias. Estritamente do ponto de vista ecotoxicológico e para as condições experimentais deste trabalho, a aplicação do nitrato como forma de intervenção para remediação dos sedimentos da Represa Ibirité não se mostrou adequada.