No description available.

Thesis (M.S.)--Texas State University--San Marcos, 2008. / Includes bibliographical references (leaves 72-77). Also available on microfilm.

Residues of picloram in four varieties of potatoes, given pre-emergence treatments with picloram at 2 oz per acre and picloram at 2 oz + linuron at 24 oz per acre were determined by electron capture gas chromatography. Average residue levels of 3.9 and 2.7 ppb (fresh weight) were obtained for the picloram and picloram + linuron treatments. This difference was significant at the 1% level. Tuber injury, ranging from formation of corky tissues on the surface to splitting, was observed with the picloram treatments. No such injury was observed with the picloram + linuron treatments. Yields were noticeably higher in the picloram + linuron treatments. The reduced picloram residues could thus be associated with the diluting effect of higher yields which resulted from the addition of linuron. A similar experiment using four varieties of carrots given either pre-emergence or post-emergence treatments with picloram at ½ and 2 oz per acre respectively gave no detectable picloram residues. Using ¹⁴C carboxyl labeled picloram this finding was further investigated and it was shown that picloram was absorbed by the foliage and roots and translocated throughout the whole plant. The leaves accumulated four times more radioactivity than the taproots. The radioactivity in the leaves and taproots was in the form of the parent picloram molecule. The picloram present in the taproot was located mainly in the xylem. A study of the stability of picloram, its potassium salt and its methyl ester under short wave ultraviolet light (253.7 nm) revealed that all three compounds were degraded into several photoproducts. The methyl ester was the least stable, being 85% degraded after one hour exposure. Picloram and its potassium salt were more stable, each being 50% decomposed after one hour exposure. Partial polymerization of all three compounds may also have taken place. / Land and Food Systems, Faculty of / Graduate

Thesis (M.S.)--Oregon State University, 2009. / Printout. Includes bibliographical references (leaves 84-87). Also available on the World Wide Web.

Adsorption and desorption of picloram (4-amino-3,5,6-trichloropicolinic acid) in soils was studied utilizing both batch technique and soil columns. The five soils from the states of Utah and California ranged from 0.6 to 18.7 percent in organic matter content, 5 to 21 percent in sesquioxides and 6.45 to 7.55 in pH. In batch studies, the factors affecting picloram adsorption-desorption included time, soil type, organic matter, herbicide concentration, temperature, pH, and inorganic electrolytes. The soils adsorbed 10.8 to 58.2 percent of the added picloram from 0.05 to 10,0 ppm of picloram aqueous solutions. Adsorption was highly correlated with organic matter (r • 0.99), pH (r •- 0.98), and aesquioxides content (r • 0.96) of the soils, Adsorption was significantly correlated with cation exchange capacity of the soils at the 0.05 level. Equilibration timo rongod from 4 to 120 hours. An incraaa in the temperature from 17.7 C to 25 C cauaad 1ncroaa•d adsorptin; raising the temperature further resulted in a decrease in adsorption. The adsorption followed the Freundlich model, but not the Langmuir, Tempkin, or B.E.T. models. Adsorption was inversely related to induced pH changes from pH 3.6 to pH 9.2. From 41.0 to 71.8 percent of the initially adsorbed picloram could be eluted with two successive extractions of deionized water from the three soils at 25 C. The desorption thereafter was slow. No evidence was found of picloram precipitation with the addition of inorganic electrolytes in aqueous solutions without soil. Divalent inorganic cations were , generally, more effective in increasing adsorption than monovalent cations. Studies of the effect of CaC12 concentrations (from 5 to 500 me/ 1) on picloram adsorption by four soils suggested an exchange type reaction, picloram acting as a cation. These interpretations were not conclusive. Column studies with two of the soils, at 1.0 and 10.0 ppm picloram concentrations and in the natural state as well as after calcium saturation, corrobated the findings of batch studies; inorganic salts did impede picloram movement in soils, presumably by increasing picloram adsorption. Applicability of a mathematical model, based on chromatographic theory, to predict picloram movement in two soils was tested. The model overestimated adsorption. However, when a lower retardation factor was used, the prediction was reasonable on the adsorption side of the herbicide distribution curve, but not the desorption side. This suggested that a distribution coefficient, based on its change with soil depth, may improve the predictability of the model.

Nos dias de hoje um grande número de pesticidas é utilizado em colheitas, agricultura, transporte de sementes, entre outros. Esses pesticidas são moléculas orgânicas que apresentam em sua estrutura grupos funcionais capazes de formar ligações com íons metálicos, que de forma natural ou por intervenção humana, são encontradas no solo. Estas espécies entram em contato no meio ambiente, e assim, interagem formando ligações, dando forma aos chamados compostos de coordenação, ou complexos. A formação destes complexos pode alterar significativamente as propriedades dos pesticidas e dos íons metálicos, podendo acentuar seu caráter tóxico, sua persistência e degradação. Neste trabalho foram escolhidos dois pesticidas que são bons exemplos deste tipo de molécula. O fungicida Thiram, que apresenta em sua estrutura átomos de enxofre, e assim interage com uma gama de íons metálicos; e o herbicida picloram, que é um derivado piridínico, o qual apresenta um átomo de nitrogênio com pares de elétrons livres e capazes de formar ligações, e um grupamento ácido na posição dois do anel também capaz de interagir com íons metálicos. Com o intuito de se entender melhor como ocorre estas interações, realizou-se este trabalho onde observou-se a complexação dos pesticidas thiram e picloram com quatro íons metálicos previamente selecionados, zinco, cobre, cádmio e chumbo. Dessa forma, deu-se início a um estudo de complexação utilizando o método de Voltametria de Redissolução Anódica em modo de Pulso Diferencial, a fim de se avaliar a ocorrência desta complexação. Para isso, contamos com duas ferramentas muito utilizadas para a avaliação da capacidade complexante de amostras, os métodos de linearização de Scatchard e Langmuir. Com a técnica utilizada foram levantadas curvas de titulação de amostras contento os pesticidas, e a partir dos dados obtidos aplicou-se os cálculos de Langmuir e Scatchard para se obter dois parâmetros importantes, a constante de estabilidade condicional do complexo formado, K\', e a concentração de ligante que participa da reação de complexação em solução, [L]T. Os dados obtidos com ambos pesticidas foram satisfatórios, indicando a ocorrência de complexos. Porém, observou-se que essa interação é maior entre o fungicida thiram e os respectivos metais do que com o herbicida picloram. As constantes de estabilidade condicional para o fungicida thiram se encontram com Log de K\' entre 6 e 7, enquanto as mesmas para os complexos formados entre o herbicida picloram e os íons metálicos se encontram entre 5 e 6. Para se confirmar as medidas de voltametria de redissolução anódica, foram realizadas medidas de espectroscopia na região do ultravioleta visível, bem como medidas de voltametria cíclica e de pulso diferencial. / Nowadays, numerous pesticides are used in crops, agriculture, transport of seeds, among others. These pesticides are organic molecules that present functional groups in their structure which are capable of forming connections with metallic ions, which, whether naturally or by human intervention, are found in the soil. These species enter in contact in the environment, and thus, they interact forming connections, giving form to the so called compound of coordination, or complex. The formation of these complexes can alter significantly the properties of both the pesticides and the metallic ions, being able to enhance toxic character, persistence and degradation. In this work, two pesticides were chosen for being good examples of this type of molecule. The fungicide Thiram, which presents atoms of sulfur in its structure, and thus interact with a range of metallic ions; and the herbicide picloram, a derived pyridinic, which presents a nitrogen atom with pairs of free electrons and capable of forming binding, and an acid group in the position two of the ring, also capable of interacting with metallic ions. In order to better understand how these interactions occur, this work focused where the complexation of pesticides thiram and picloram was observed with four metallic ions previously selected, zinc, copper, cadmium and lead. Hence, a study of complexation was started using the method of Differential Pulse Anodic Stripping Voltammetry, in order to evaluate the occurrence of the complexation. For that, we counted on two tools very frequently used for the viii evaluation of the metal-binding capacity of samples, namely, the linearization methods of Scatchard and Langmuir. Titration curves of the samples containing the pesticide were obtained using the technique, and starting from the data, the calculations of Langmuir and Scatchard were applied in order to obtain two important parameters, stability conditional constant of the formed compound, K\', as well as the ligand concentration that participates in the reaction complexation in solution, [L]T. The data obtained with both pesticides were satisfactory, indicating the occurrence of complexes. However, it was observed that the interaction is larger between the fungicide thiram and the respective metals than with the herbicide picloram. The constants of conditional stability for the fungicide thiram are with LogK\' between 6 and 7, while the same ones for the compounds formed between the herbicide picloram and the metallic íons are between 5 and 6. To confirm the measures of anodic stripping voltammetry, spectroscopy measures were carried out in the area of the visible ultraviolet, as well as measures of cyclic voltammetry and of differential pulse.

Nos dias de hoje um grande número de pesticidas é utilizado em colheitas, agricultura, transporte de sementes, entre outros. Esses pesticidas são moléculas orgânicas que apresentam em sua estrutura grupos funcionais capazes de formar ligações com íons metálicos, que de forma natural ou por intervenção humana, são encontradas no solo. Estas espécies entram em contato no meio ambiente, e assim, interagem formando ligações, dando forma aos chamados compostos de coordenação, ou complexos. A formação destes complexos pode alterar significativamente as propriedades dos pesticidas e dos íons metálicos, podendo acentuar seu caráter tóxico, sua persistência e degradação. Neste trabalho foram escolhidos dois pesticidas que são bons exemplos deste tipo de molécula. O fungicida Thiram, que apresenta em sua estrutura átomos de enxofre, e assim interage com uma gama de íons metálicos; e o herbicida picloram, que é um derivado piridínico, o qual apresenta um átomo de nitrogênio com pares de elétrons livres e capazes de formar ligações, e um grupamento ácido na posição dois do anel também capaz de interagir com íons metálicos. Com o intuito de se entender melhor como ocorre estas interações, realizou-se este trabalho onde observou-se a complexação dos pesticidas thiram e picloram com quatro íons metálicos previamente selecionados, zinco, cobre, cádmio e chumbo. Dessa forma, deu-se início a um estudo de complexação utilizando o método de Voltametria de Redissolução Anódica em modo de Pulso Diferencial, a fim de se avaliar a ocorrência desta complexação. Para isso, contamos com duas ferramentas muito utilizadas para a avaliação da capacidade complexante de amostras, os métodos de linearização de Scatchard e Langmuir. Com a técnica utilizada foram levantadas curvas de titulação de amostras contento os pesticidas, e a partir dos dados obtidos aplicou-se os cálculos de Langmuir e Scatchard para se obter dois parâmetros importantes, a constante de estabilidade condicional do complexo formado, K\', e a concentração de ligante que participa da reação de complexação em solução, [L]T. Os dados obtidos com ambos pesticidas foram satisfatórios, indicando a ocorrência de complexos. Porém, observou-se que essa interação é maior entre o fungicida thiram e os respectivos metais do que com o herbicida picloram. As constantes de estabilidade condicional para o fungicida thiram se encontram com Log de K\' entre 6 e 7, enquanto as mesmas para os complexos formados entre o herbicida picloram e os íons metálicos se encontram entre 5 e 6. Para se confirmar as medidas de voltametria de redissolução anódica, foram realizadas medidas de espectroscopia na região do ultravioleta visível, bem como medidas de voltametria cíclica e de pulso diferencial. / Nowadays, numerous pesticides are used in crops, agriculture, transport of seeds, among others. These pesticides are organic molecules that present functional groups in their structure which are capable of forming connections with metallic ions, which, whether naturally or by human intervention, are found in the soil. These species enter in contact in the environment, and thus, they interact forming connections, giving form to the so called compound of coordination, or complex. The formation of these complexes can alter significantly the properties of both the pesticides and the metallic ions, being able to enhance toxic character, persistence and degradation. In this work, two pesticides were chosen for being good examples of this type of molecule. The fungicide Thiram, which presents atoms of sulfur in its structure, and thus interact with a range of metallic ions; and the herbicide picloram, a derived pyridinic, which presents a nitrogen atom with pairs of free electrons and capable of forming binding, and an acid group in the position two of the ring, also capable of interacting with metallic ions. In order to better understand how these interactions occur, this work focused where the complexation of pesticides thiram and picloram was observed with four metallic ions previously selected, zinc, copper, cadmium and lead. Hence, a study of complexation was started using the method of Differential Pulse Anodic Stripping Voltammetry, in order to evaluate the occurrence of the complexation. For that, we counted on two tools very frequently used for the viii evaluation of the metal-binding capacity of samples, namely, the linearization methods of Scatchard and Langmuir. Titration curves of the samples containing the pesticide were obtained using the technique, and starting from the data, the calculations of Langmuir and Scatchard were applied in order to obtain two important parameters, stability conditional constant of the formed compound, K\', as well as the ligand concentration that participates in the reaction complexation in solution, [L]T. The data obtained with both pesticides were satisfactory, indicating the occurrence of complexes. However, it was observed that the interaction is larger between the fungicide thiram and the respective metals than with the herbicide picloram. The constants of conditional stability for the fungicide thiram are with LogK\' between 6 and 7, while the same ones for the compounds formed between the herbicide picloram and the metallic íons are between 5 and 6. To confirm the measures of anodic stripping voltammetry, spectroscopy measures were carried out in the area of the visible ultraviolet, as well as measures of cyclic voltammetry and of differential pulse.

These studies were conducted on several central Texas agricultural producers?? properties, the Stiles Farm Foundation, the Texas Agricultural Experiment Station, and the Texas A&M University campus. First, an experimental herbicide from Dow AgroSciences, GF-884, was evaluated for effectiveness in controlling three annual and three perennial weed species in production pasture lands and hay meadows. Several rates of GF-884 were examined and evaluated against three registered pasture products and one non-selective herbicide. Next, GF-884 was assessed for tolerance on two common bermudagrass hybrids (Cynodon dactylon (L.) Pers.) at three progressive rates with and without adjuvant. Finally, the herbicides, picloram and fluroxypyr, were applied to common ragweed (Ambrosia artemisiifolia L.) to characterize their individual absorption and translocation and assess any influence one might have on the other. GF-884 applied at rates of 0.91 and 1.14 kg a.e./ha provided >85% and >75% control of the annual and perennial weed species evaluated, respectively. These same rates of GF-884 consistently provided control that was equivalent or better than thatachieved with the registered products. No differences were observed among treatments when shoots from the perennial species were evaluated 12 months following treatment application. The tolerance experiments utilized GF-884 at rates twice that used to evaluate weed control efficacy. These elevated rates did not result in discernable influences on yield or forage quality for either hybrid forage grass when compared to untreated areas. The efficacy and tolerance observations suggest that GF-884 applied at the highest recommended weed control rate can effectively control several annual and perennial weed species without imparting detrimental effects to the hybrid bermudagrass being produced. Finally, in the presence of fluroxypyr, 14C picloram absorption was maintained throughout all sampling intervals. Picloram applied alone, maximized 14C absorption at 6 HAT then declined significantly. At the final sampling, 14C from picloram applied alone was in greater concentration in the treated leaf and the root. Picloram significantly decreased absorption of 14C fluroxypyr. Fluroxypyr alone maintained 14C absorption throughout all samplings, whereas the combination maximized at 12 HAT. Initially, picloram limited 14C translocation, however at 6, 12, and 24 HAT this was not evident.

Orientador: Luiz Lonardoni Foloni / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-10T18:30:08Z (GMT). No. of bitstreams: 1 Mantovani_EdemirCelso_D.pdf: 2615689 bytes, checksum: c5019f633a530205ade647803d809fa8 (MD5) Previous issue date: 2007 / Resumo: O picloram é um dos herbicidas mais usados no controle de plantas daninhas das áreas de pastagens, especialmente as de difícil erradicação. Muitos são os relatos de contaminação de poços e nascentes com resíduos de herbicidas em decorrência de sua lixiviação em solos. Devido à falta de conhecimento e de dados disponíveis sobre o destino do picloram em solos brasileiros, fazem-se necessárias pesquisas nessas condições de solo e clima para avaliar o potencial de contaminação de águas subterrâneas com resíduos desse herbicida. Com o objetivo de avaliar a movimentação vertical do herbicida picloram em condições de campo e por simulações utilizando-se um simulador, testou-se a hipótese de que uso do herbicida picloram, em ambiente controlado e através de resultados de um simulador matemático, é adsorvido à argila e aos solos com elevado teor de matéria orgânica, apresentando baixa mobilidade vertical e pequeno potencial de contaminação de águas subterrâneas. O trabalho foi conduzido no Campo Experimental da Faculdade de Engenharia Agrícola da UNICAMP, utilizando-se lisímetro de drenagem modificado de 2 m de diâmetro e 3 m de profundidade, com 10 pontos verticais, através dos quais foram coletadas amostras de água da chuva. As amostras foram coletadas um dia após as chuvas no período de outubro de 2006 a março de 2007 e submetidas à Análise Cromatográfica Gasosa com detecção por espectrômetro de massas ¿ CG/MSD. Em virtude de não se ter informações sobre os valores de (coeficiente de sorção) e (meia-vida) para o herbicida picloram nas condições dos solos argilosos, foi necessário obter estes, em condições de Laboratório a . Para as simulações utilizou-se o simulador MACRO 5.1. Os dados encontrados através das análises das amostras coletadas em campo e das simulações no MACRO 5.1 indicaram uma presença decrescente do herbicida picloram ao longo do tempo, confirmando a hipótese de baixa mobilidade vertical desse herbicida, numa curva decrescente, e indicando, para este solo, pequeno potencial de contaminação das águas subterrâneas. O simulador mostrou a movimentação do herbicida picloram no perfil do solo, porém de uma forma subestimada / Abstract:Picloram is one of the most used herbicides in the control of weeds in pastures areas, especially the ones of difficult eradication. Many are the stories of wells and springs contamination with herbicides residues as a result of its leaching in grounds. Due to the lack of knowledge and available data on the destination of the picloram in brazilian grounds, researches in these soil conditions and climate become necessary to evaluate the potential of underground water contamination with residues of such herbicide. With the objective of evaluating the vertical movement of the picloram herbicide in field conditions and by simulation using a simulator, a test was made to verify the hypothesis that the use of the picloram herbicide, in controlled environment and through results of a mathematical simulator, is absorbed to the clay and ground with high amounts of organic substance, presenting low vertical mobility and low potential of underground water contamination. The work was lead in the Experimental Field of the College of Agricultural Engineering of UNICAMP, having used draining modified lysimeter 2 m diameter per 3 m depth, with 10 vertical points, through which water samples of rain had been collected. The samples were collected 1 day after rains in the period from October 2006 to March 2007 and submitted to Gas Chromatographic Analysis with detection by means of mass espectrometro - CGMSD. Because there was no information about values (sorption coefficient) and (half-life) for the Picloram herbiced under clay soils, it was necessary to obtain these, under laboratory conditions. For the simulations a MACRO 5.1 simulator was used. The data found through the analyses of the samples collected in field and the simulations in MACRO 5.1 indicated a decreasing presence of the picloram herbicide during this time, confirming the hypothesis of low vertical mobility of this herbicide, in a decreasing curve, and indicating, for this ground, low potential of contamination of underground waters. The simulator showed a Picloram herbicide movement in the soil profile, but in an underestimated way / Doutorado / Agua e Solo / Doutor em Engenharia Agrícola

A extensa utilização de pesticidas na agricultura moderna tem contribuído para um aumento na contaminação do meio ambiente. Os Hidróxidos Duplos Lamelares (HDLs) ou argilas aniônicas, apresentam uma estrutura lamelar na qual uma variedade de ânions podem ser intercalados entre as lamelas através de interações eletrostáticas. Estes materiais lamelares podem ser utilizados em processos de adsorção/sorção e como suporte para a liberação lenta de compostos químicos. Assim, os principais objetivos deste trabalho foram: o estudo da sorção de ânions orgânicos de herbicidas ácidos 2,4-D, MCPA e Picloram utilizados na agricultura nacional, pela regeneração de HDLs de Mg-Al-CO3 calcinado e por troca aniônica em HDLs de Mg-Al-Cl. Para isso foram investigados a cinética do processo de sorção, além da determinação das isotermas em dois valores diferentes de pH. Assim, estes herbicidas foram intercalados em HDLs de Mg-Al, utilizando dois métodos de síntese indireta: regeneração do material calcinado e troca aniônica em solução, além do método de síntese direta por coprecipitação, sendo os materiais devidamente caracterizados. Todos os materiais obtidos, intercalados com cada um dos herbicidas, foram utilizados para o estudo da cinética de liberação dos mesmos em água. Os materiais obtidos por regeneração contendo cada um dos três herbicidas foram utilizados também no estudo da lixiviação em colunas de solo e no estudo de bio-ensaio com plantas, para testar a eficiência dos HDLs como suportes na liberação lenta dos herbicidas. A partir do estudo da cinética do processo de sorção dos ânions orgânicos presentes em solução utilizando HDLs de Mg-Al contendo cloreto ou carbonato após a calcinação, observou-se que a remoção dos ânions ocorreu através dos processos de troca aniônica no caso do HDL contendo cloreto, ou de regeneração da estrutura lamelar no caso do HDL calcinado. A intercalação dos ânions orgânicos na posição vertical foi verificada no processo de adsorção/sorção, e se mostrou dependente da concentração do herbicida em solução. O HDL calcinado apresentou a maior eficiência na remoção dos ânions da solução. Os herbicidas suportados em HDLs, apresentaram uma liberação em água mais lenta do que os mesmos em sua forma livre, e não se mostrou dependente do método de preparação da matriz utilizada. Os resultados dos estudos de lixiviação utilizando como matriz o HDL obtido por regeneração, demonstraram que os HDLs são bons suportes para os herbicidas pois apresentaram uma liberação lenta do ingrediente ativo, principlamente para o herbicida Picloram. O bio-ensaio mostrou que a forma de liberação dos herbicidas suportados foi eficiente no controle da germinação das sementes de plantas em aplicações pré-emergenciais. / The extensive use of pesticides in modern agriculture has been contributing to an increase in environmental contamination. Layered Double Hydroxides (LDHs), or anionic clays, bear a layered structure, and a variety of anions can be intercalated between these layers through electrostatic interactions. These layered materials can be used in adsorption/sorption processes and in the slow release of chemical compounds. So this work aims at studing the sorption of the acid herbicides bearing organic anions 2,4-D, MCPA and Picloram, used in national agriculture, through regeneration of calcined Mg-Al-CO3 LDH and anion exchange of Mg-Al-Cl ? LDH. For this purpose, the kinetics of the sorption process was investigated, and the determination of isotherms in two different pH values was carried out. The herbicides were intercalated in Mg-Al ? LDH using two indirect synthesis methods: regeneration of the calcined material and anion exchange in solution; besides the direct synthesis method by coprecipitation. The obtained materials were properly characterized. All the obtained materials, intercalated with each of the herbicides, were used in a kinetic release study in water. The materials obtained by regeneration were also used in a leaching and in a bioassay study, to test the efficiency of LDHs as supports for the slow release of herbicides. From the kinetic sorption process of the organic anions in solution using Mg-Al ? LDH containing chloride or carbonate after calcination, it was observed that the removal of anions occurred through an anionic exchange process in the case of the LDH containing chloride, or through regeneration of the layered structure in the case of the calcined LDH. The intercalation of organic anions in a vertical position was observed in the adsorption/sorption process, and it was shown to be dependent on the herbicide concentration in solution. The calcined LDH was the most efficient for removal of anions in solution. The herbicides supported on LDHs, presented a slower release in water than the same compounds in their free form, and the release behavior was not dependent on the methodology used for the preparation of the matrix. Leaching study results using the LDH obtained by regeneration as matrix demonstrated a slow release of the active ingredient, mainly for the Picloram herbicide. The bioassay showed that the release behavior of the supported herbicides was efficient in the control of plant seeds germination at preemergence applications.