A dinâmica dos herbicidas no solo é influenciada pela umidade e pela quantidade e qualidade da matéria orgânica, que são variáveis nos agregados organominerais. Os objetivos foram avaliar a influência do grau de umidade na mineralização e sorção do 2,4-D (ácido fraco) e Diuron (não ionizável), em quatro latossolos com diferentes quantidades de matéria orgânica do solo (M.O.S.), avaliar a influência do tamanho do agregado (> 150, 54 – 150, 21 – 53, 2 – 20 e < 2 mm) na sorção dos herbicidas e determinar o grau de humificação para explicar possíveis diferenças na sorção. Foram utilizadas amostras superficiais (0 - 0,2 m) de um Latossolo Amarelo distrófico (LAd) (Piracicaba/SP), de um Latossolo Amarelo ácrico (LAw) (Uberlândia/MG), de um Latossolo Vermelho ácrico (LVw-1) (Uberlândia/MG) e de um Latossolo Vermelho ácrico (LVw-2) (Canoinhas/SC). Foram determinados os valores de pH (em H2 O, KCl 1,0 mol L -1 e CaCl2 0,01 mol L -1 ), a quantidade de M.O.S., de fósforo, de K + , de Ca 2+ , de Mg 2+ , de Al 3+ e estimada a soma H+Al. Os óxidos de ferro, de alumínio e de silício foram quantificados após extração com ácido sulfúrico, os óxidos de ferro “livre” e mal cristalinizado também foi determinado e a análise granulométrica foi efetuada pelo método do densímetro, sendo quantificada também a argila dispersa em água (ADA). Foi determinada a mineralogia por difração de raio-X. Foram quantificadas as frações organominerais dos solos. Foram dispersos 40 g de solo em 160 mL de água destilada, que foram agitados a 160 agitações min -1 por 16 h e sonificada por 15 min. Após disperso, o solo foi peneirado para separar os agregados > 150 mm e entre 53 e 150 mm. Os agregados menores que 53 mm foram separados por sedimentação. Foi determinado o carbono orgânico dos agregados e do solo por combustão. A atividade microbiana dos solos foi determinada pelo método da radiorespirometria. Amostras dos solos foram incubadas com 14 C-2,4-D e 14 C-diuron por 42 dias umedecidas a 25, 50 e 75 % da capacidade de campo em sala climatizada semi-escura a 22 ± 2 o C, após foram realizadas três extrações com CaCl2 0,01 mol L -1 . O solo foi então fracionado após oxidação para determinar o os herbicidas sorvidos no solo e, posteriormente nos diferentes agregados. O grau de humificação das amostras foi determinado por fluorescência. A mineralização do 2,4-D foi de 62 % no LAd a 75 % da capacidade de campo. A difusão foi responsável pela sorção dos herbicidas. O 2,4-D foi menos sorvido no LAd, que tinha maior pH e menor quantidade de M.O.S.. Os solos apresentaram maior quantidade de agregados > 150 mm. Os agregados organominerais de diâmetro menores que 53 mm apresentaram maior acúmulo de carbono. A exceção do LAd, os herbicidas foram mais sorvidos pelos agregados maiores que 53 mm. A sorção só aumentou nos agregados menores que 53 mm, quando a amostra foi incubada a 75 % da capacidade de campo. Porém, no caso do diuron, isto só foi verificado no LAw e LVw-1. As sucessivas extrações alteraram a estabilidade dos agregados. O LAd que se localiza em uma área de cultivo tem maior grau de humificação que o LVw-2 localizado em uma área não cultivada. Os agregados de diâmetro entre 53 e 150 mm, foram os que tiveram maior grau de humificação nos solos. / The dynamic of herbicides in soils is influenced by soil moisture and organic matter contents and also by their quality, which are variable in the organic-mineral aggregates of the soils. The aims of this research were to evaluate the effects of soil moisture on the mineralization and sorption of the herbicides 2,4-D (weak acid) and diuron (non-ionic), in four Oxisols with different contents of soil organic matter (SOM), as well as to evaluate the influence of aggregate sizes (> 150, 54 – 150, 21 – 53, 2 – 20 and < 2 mm) and degree of humification in the sorption of these herbicides. Surface samples (0 – 0.2 m) of one Xanthic Hapludox (LAd, from Piracicaba/SP), one Xanthic Acrudox (LAw, from Uberlândia/MG), and two Anionic Acrudox (LVw-1 from Uberlândia/MG and LVw-2 from Canoinhas/SC) were collected. SOM, phosphorus, K + , Ca 2+ , and Mg 2+ contents and pH values (in H2 O, in KCl 1.0 mol L -1 and in CaCl2 0.01 mol L -1 ) were measured, whereas H+Al was calculated. Fe, Al, and Si oxides were quantified after soil extraction with H2SO4. Free and amorphous Fe oxides were determined by DCB and oxalate method, respectively. Granulometric analysis and water dispersed clay (WDC) were quantified by the densimeter method. The mineralogy was evaluated by X-ray diffraction. In order to quantify soil organic-mineral aggregates, 40 g of soil was added to 160 mL of distilled water in centrifuge tubes, which were shaken for 16 h at 160 rpm and sonicated for 15 min at 240 W. The aggregates > 150 and 53 – 150 mm were obtained by sieving, whereas the aggregates < 53 mm were obtained by sedimentation. Soil and aggregate organic carbon contents were obtained by combustion. The soil microbial activity was obtained by the radiorespirometry method. Soils were incubated with 14 C-2,4-D and 14 C-diuron, for 42 d at 25, 50 and 75 % of the field capacity and remained in a semi-dark room at controlled temperature of 22 ± 2 o C. Then, the pesticides were extracted three times with CaCl2 0.01 mol L -1 and, afterwards, the soil samples were fractionated in order to quantify the amount of herbicides in the aggregates. In these, the degree of humification was obtained by fluorescence. Diffusion markedly affected the herbicides sorption. For example, 2,4-D mineralization was 62 % on LAd only at 75 % field capacity. As expected, 2,4-D was less sorbed on LAd that had higher pH and lower SOM content. In general, the soils presented higher amounts of aggregates > 150 mm. The organic-mineral aggregates < 53 mm presented higher organic carbon content. However, the herbicides were more sorbed in the aggregates > 53 mm, except for LAd. When the soil were at 75 % of the field capacity, the sorption increased in the aggregates < 53 mm for 2,4-D, but it was only verified for LAw and LVw-1 for diuron. The successive extractions altered the aggregate stability. The LAd located in a tilled area had higher degree of humification than the LVw-2 located in a non-tilled area. The soil aggregates between 53 and 150 mm presented higher degree of humification.

<p>Den biologiska mångfalden är viktig inom lantbruket. Jordbrukslandskapets mångfald är vacker för människan att se på och spännande och rogivande att vistas i. Mångfalden innehåller även en genbank som kan bli mycket etydelsefull i framtiden. Dessutom innebär oftast en rik mångfald bland ogräsen även en rik mångfald bland insekter och andra djur, däribland skadeinsekternas predatorer, vilket bidrar till produktiva åkrar. Ogräsens mångfald på åkern beror till stor del på geografiskt läge, klimat och berggrund. Även odlingssättet och tillhörande odlingsåtgärder är avgörande för hur åkerns ogräsflora ser ut. En odlingsåtgärd som har ett stort inflytande över ogräsflorans sammansättning, är användningen, eller uteslutandet, av herbicider. </p><p>Uppsatsens fältstudie består av ogräsinventeringar genomförda på två åkrar – en konventionellt odlad och en ekologiskt odlad. Den konventionella åkern är behandlad med syntetiska herbicider och den ekologiska är det inte. Studien visar att den ekologiska åkern hade fler arter, en rikligare mångfald, och många fler plantor än den konventionella åkern. Artsammansättningen tyder på att den konventionella åkern var något mer näringsrik och hade ett lägre pH.</p> / <p>Biological diversity is important in agricultural systems. The diversity of the agricultural landscape is beautiful to the human eye and it provides an exciting as well as soothing environment. Diversity also denotes genetic resources that can be of great importance in the future. Furthermore, a high biological diversity of weeds most often means a high diversity of insects and other animals, among them the predators of pests, which contributes to high productivity of the arable fields. The diversity of weed in a field depends on its geographical location, the climate and the bedrock. Other factors of great importance to the composition of the weed flora are the farming methods (conventional/ecological) and the specific measures used. One measure that has a high influence on the composition of the weed flora is the use, or exclusion, of herbicides. </p><p>The field study of this paper consists of weed inventories of two arable fields – the first cultivated per traditional methods and the second per ecological methods. Herbicides are used in the conventional field but not in the ecological one. The study shows that the ecological field had more secies, a greater diversity, and far more plants than the conventional field. The composition of the weed species indicates that the conventional field had a slightly higher nutritive value and a lower pH value.</p>

Graduation date: 2004

Im Rahmen dieser Arbeit gelang es, katalytische Antikörper zur Hydrolyse von Benzylphenylcarbamaten sowie zahlreiche monoklonale Antikörper gegen Haptene herzustellen.<br /> <br /> Es wurden verschiedene Hapten-Protein-Konjugate unter Verwendung unterschiedlicher Kopplungsmethoden hergestellt und charakterisiert. Zur Generierung der hydrolytisch aktiven Antikörper wurden Inzuchtmäuse mit KLH-Konjugaten von 4 Übergangszustandsanaloga (ÜZA) immunisiert. Mit Hilfe der Hybridomtechnik wurden verschiedene monoklonale Antikörper gegen diese ÜZA gewonnen. Dabei wurden sowohl verschiedene Immunisierungsschemata als auch verschiedene Inzuchtmausstämme und Fusionstechniken verwendet. Insgesamt wurden 32 monoklonale Antikörper gegen die verwendeten ÜZA selektiert. Diese Antikörper wurden in großen Mengen hergestellt und gereinigt. <br /> <br /> Zum Nachweis der Antikörper-vermittelten Katalyse wurden verschiedene Methoden entwickelt und eingesetzt, darunter immunologische Nachweismethoden mit Anti-Substrat- und Anti-Produkt-Antikörpern und eine photometrische Methode mit Dimethylaminozimtaldehyd. Der Nachweis der hydrolytischen Aktivität gelang mit Hilfe eines Enzymsensors, basierend auf immobilisierter Tyrosinase. Die Antikörper N1-BC1-D11, N1-FA7-C4, N1-FA7-D12 und R3-LG2-F9 hydrolysierten die Benzylphenylcarbamate POCc18, POCc19 und Substanz 27. Der Nachweis der hydrolytischen Aktivität dieser Antikörper gelang auch mit Hilfe der HPLC. <br /> <br /> Der katalytische Antikörper N1-BC1-D11 wurde kinetisch und thermodynamisch untersucht. Es wurde eine Michaelis-Menten-Kinetik mit Km von 210 &#181;M, vmax von 3 mM/min und kcat von 222 min-1 beobachtet. Diese Werte korrelieren mit den Werten der wenigen bekannten Diphenylcarbamat-spaltenden Abzyme. Die Beschleunigungsrate des Antikörpers N1-BC1-D11 betrug 10. Das ÜZA Hei3 hemmte die hydrolytische Aktivität. Dies beweist, dass die Hydrolyse in der Antigenbindungsstelle stattfindet. Weiter wurde zwischen der Antikörperkonzentration und der Umsatzgeschwindigkeit eine lineare Abhängigkeit festgestellt. Die thermodynamische Gleichtgewichtsdissoziationskonstante KD des Abzyms von 2,6 nM zeugt von einer sehr guten Affinität zum ÜZA. <br /> <br /> Hydrolytisch aktiv waren nur Antikörper, die gegen das Übergangszustandsanalogon Hei3 hergestellt worden waren. Es wird vermutet, dass die Hydrolyse der Benzylphenylcarbamate über einen Additions-Eliminierungsmechanismus unter Ausbildung eines tetraedrischen Übergangszustandes verläuft, dessen analoge Verbindung Hei3 ist.<br /> <br /> Im Rahmen der Generierung von Nachweisantikörpern zur Detektion der Substratabnahme bei der Hydrolyse wurden Anti-Diuron-Antikörper hergestellt. Einer der Antikörper (B91-CG5) ist spezifisch für das Herbizid Diuron und hat einen IC50-Wert von 0,19 &#181;g/l und eine untere Nachweisgrenze von 0,04 &#181;g/l. Ein anderer Antikörper (B91-KF5) reagiert kreuz mit einer Palette ähnlicher Herbizide. Mit diesen Antikörpern wurde ein empfindlicher Labortest, der ein Monitoring von Diuron auf Grundlage des durch die Trinkwasserverordnung festgeschriebenen Wertes für Pflanzenschutzmittel von 0,1 &#181;g/l erlaubt, aufgebaut. <br /> <br /> Der Effekt der Anti-Diuron-Antikörper auf die Diuron-inhibierte Photosynthese wurde in vitro und in vivo untersucht. Es wurde nachgewiesen, dass sowohl in isolierten Thylakoiden, als auch in intakten Algen eine Vorinkubation der Anti-Diuron-Antikörper mit Diuron zur Inaktivierung seiner Photosynthese-hemmenden Wirkung führt. Wurde der Elektronentransport in den isolierten Thylakoiden oder in Algen durch Diuron unterbrochen, so führte die Zugabe der Anti-Diuron-Antikörper zur Reaktivierung der Elektronenübertragung. / Attempts to produce catalytic antibodies for hydrolysis of arylcarbamates and arylureas:<br /> The aim of the investigations was to produce antibodies which are able to cleave herbicides resistant to naturally occuring enzymes. Structurally similar carbamate and urea derivatives were chosen for the experiments.<br /> <br /> Phosphonate derivatives were synthesized that mimick possible transition state analogues in structure and charge. Mice were immunized with 4 different derivatives after conjugating them to carrier proteins. 32 hybridomas were established that produce monoclonal antibodies binding to these derivatives. <br /> <br /> The possible cleavage of substrates was determined by immunoassays with monoclonal antibodies against the substrate and the products and with a photometric method based on dimethylaminocinammonaldehyde. The measuring of cleavage products was succeeded by an amperometric method. The enzyme sensor was based on immobilized tyrosinase which oxidizes p-chlorophenol and phenol.<br /> <br /> The antibodies N1-BC1-D11, N1-FA7-C4, N1-FA7-D12 und R3-LG2-F9 hydrolysed the benzylphenylcarbamates POCc18, POCc19 und Substance 27. The hydrolytic activity of these antibodies was also succeeded with HPLC.<br /> <br /> The catalytic antibody N1-BC1-D11 was investigated kinetically and thermodynamically. A Michaelis-Menten-Kinetic was observed (at pH 8.0 exhibited a Km 210 &#181;M, a vmax 3 mM/min and a kcat 222 min-1). These values are in the range of the values obtained for the antibody-catalysed hydrolysis of diphenylcarbamates. The rate enhancement of N1-BC1 was 10. The reaction was completely inhibited by stoichiometric quantities of the transition state analogue Hei3. This is consistent with the affinity of the abzyme to Hei3 of 2.6 nM, determined by BIAcore assay.<br /> <br /> Only antibodies generated against Hei3 showed hydrolytic activity. The hydrolysis of benzylphenylcarbamates presumably occurs via an addition-elimination-Mechanism involving a tetrahedral intermediate. <br /> <br /> In summary, this work presents the first example of antibody-catalysed hydrolysis of benzylphenylcarbamates. <br /> <br /> Monoclonal anti-diuron antibodies were generated that bind to the herbicide diuron with an extremely low equilibrium dissociation constant. A sensitive immunoassay with a low detection limit of 0.2 nM for diuron was established. This is the most sensitive immunological method for detection of diuron known so far.<br /> <br /> These antibodies were also used in vitro and in vivo to prevent diuron-dependent inhibition of photosynthesis or to restore photosynthesis after inhibition. In isolated thylakoids prepared from spinach leaves (Spinacia oleracea L.) the diuron-inhibited Hill reaction was reconstituted immediately following the addition of the monoclonal antibodies. In an in vivo approach the photosynthetic oxygen evolution of the cell wall deficient mutant (cw 15) of the green alga Chlamydomonas reinhardtii Dangeard was monitored. The antibodies prevented the diuron-dependent inhibition of photosynthesis and restored photosynthesis after inhibition. Transgenic plants that synthesize and accumulate these antibodies or antibody fragments and are therefore diuron-resistant can be created.

Den biologiska mångfalden är viktig inom lantbruket. Jordbrukslandskapets mångfald är vacker för människan att se på och spännande och rogivande att vistas i. Mångfalden innehåller även en genbank som kan bli mycket etydelsefull i framtiden. Dessutom innebär oftast en rik mångfald bland ogräsen även en rik mångfald bland insekter och andra djur, däribland skadeinsekternas predatorer, vilket bidrar till produktiva åkrar. Ogräsens mångfald på åkern beror till stor del på geografiskt läge, klimat och berggrund. Även odlingssättet och tillhörande odlingsåtgärder är avgörande för hur åkerns ogräsflora ser ut. En odlingsåtgärd som har ett stort inflytande över ogräsflorans sammansättning, är användningen, eller uteslutandet, av herbicider. Uppsatsens fältstudie består av ogräsinventeringar genomförda på två åkrar – en konventionellt odlad och en ekologiskt odlad. Den konventionella åkern är behandlad med syntetiska herbicider och den ekologiska är det inte. Studien visar att den ekologiska åkern hade fler arter, en rikligare mångfald, och många fler plantor än den konventionella åkern. Artsammansättningen tyder på att den konventionella åkern var något mer näringsrik och hade ett lägre pH. / Biological diversity is important in agricultural systems. The diversity of the agricultural landscape is beautiful to the human eye and it provides an exciting as well as soothing environment. Diversity also denotes genetic resources that can be of great importance in the future. Furthermore, a high biological diversity of weeds most often means a high diversity of insects and other animals, among them the predators of pests, which contributes to high productivity of the arable fields. The diversity of weed in a field depends on its geographical location, the climate and the bedrock. Other factors of great importance to the composition of the weed flora are the farming methods (conventional/ecological) and the specific measures used. One measure that has a high influence on the composition of the weed flora is the use, or exclusion, of herbicides. The field study of this paper consists of weed inventories of two arable fields – the first cultivated per traditional methods and the second per ecological methods. Herbicides are used in the conventional field but not in the ecological one. The study shows that the ecological field had more secies, a greater diversity, and far more plants than the conventional field. The composition of the weed species indicates that the conventional field had a slightly higher nutritive value and a lower pH value.

El glifosat, N-(fosfonometil) glicina, és un dels herbicides més utilitzats arreu del món a causa de la seva baixa toxicitat i al seu ampli espectre d'aplicació. A conseqüència del gran ús que se'n fa, és necessari monitoritzar aquest compost i el seu principal metabòlit, l'àcid aminometilfosfònic (AMPA), en el medi ambient. S'han descrit diversos mètodes instrumentals basats en cromatografia de gasos (GC) i de líquids (HPLC), sent aquesta darrera l'opció més favorable a causa del caràcter polar dels anàlits. Per assolir nivells de concentració baixos cal, però, la preconcentració dels anàlits.En aquest treball s'estudien diferents alternatives amb aquest objectiu. S'ha avaluat la tècnica de membrana líquida suportada (SLM) on la membrana consisteix en una dissolució orgànica, que conté un transportador (en el nostre cas, un bescanviador d'anions comercial, Aliquat 336), que impregna un suport polimèric microporós que se situa entre dues solucions aquoses: la de càrrega, que conté els anàlits inicialment, i la receptora, on es retenen els anàlits després del seu transport a través de la membrana. Les condicions d'extracció més adequades s'obtenen treballant en medi bàsic amb NaOH on els anàlits estan en forma aniònica i les majors recuperacions s'obtenen amb HCl 0,1 M o NaCl 0,5 M, la qual cosa indica que l'ió clorur és la força impulsora del transport.Un cop dissenyat el sistema, es duen a terme experiments de preconcentració amb dues geometries diferents: un sistema de membrana laminar (LSLM) on recircula la fase receptora i un sistema de fibra buida (HFSLM). Els millors resultats s'obtenen amb el mòdul de fibra buida, amb factors de concentració de 25 i 3 per a glifosat i AMPA, respectivament, fent recircular durant 24 hores 100 ml de solució de càrrega i 4 ml de solució receptora. També s'aplica una tècnica més selectiva, la cromatografia d'afinitat amb ió metàl·lic immobilitzat (IMAC), basada en la interacció entre els anàlits i un metall immobilitzat en una resina a través d'un grup funcional d'aquesta. En aquest estudi s'immobilitza pal·ladi al grup funcional 8-hidroxiquinoleïna de la resina amb matriu acrílica Spheron Oxine 1000 i s'avalua per a l'extracció i preconcentració de glifosat i AMPA. Per a ambdós anàlits l'adsorció és del 100 % i les recuperacions són superiors al 80 % i al 60 % per a glifosat i AMPA, respectivament, utilitzant HCl 0,1 M + NaCl 1 M com a eluent. Aquests resultats es comparen amb els obtinguts amb dues resines més, també carregades amb pal·ladi: Iontosorb Oxin 100, que té el mateix grup funcional però matriu de cel·lulosa, i Spheron Thiol 1000, on el grup funcional és un tiol i la matriu també és acrílica. Per al glifosat els resultats són similars amb totes les resines, però per a l'AMPA la resina Spheron Thiol és la única que proporciona recuperacions superiors al 93 %.Finalment, una altra opció estudiada és l'acoblament de dues columnes de cromatografia líquida (LC-LC). En l'estudi l'objectiu és millorar el mètode existent per a glifosat i AMPA en aigües naturals on el LOD era de 0,25 ug/l. El mètode consisteix en la derivatització precolumna amb el reactiu fluorescent FMOC i l'anàlisi amb l'acoblament LC-LC-fluorescència. Variant lleugerament les condicions de derivatització s'aconsegueix quantificar 0,1 ug/l de glifosat i AMPA. Es fortifiquen aigües naturals amb 0,1, 1 i 10 ug/l dels anàlits per validar el mètode. S'obtenen recuperacions d'entre el 85 % i el 100 %, amb desviacions estàndard relatives inferiors al 8 %. Aplicant una tècnica de preconcentració prèvia a la derivatització i anàlisi utilitzant una resina de bescanvi aniònic, Amberlite IRA-900, es millora la sensibilitat del mètode i s'assoleix un LOD per al glifosat de 0,02 ug/l. / Glyphosate, N-(phosphonomethyl)glycine, is one of the most widely used herbicides in the world due to its low mammal toxicity. Therefore, there is a great interest in the monitoring of this compound and its major metabolite aminomethylphosphonic acid (AMPA), in environmental matrices. A great variety of methods based on gas chromatography (GC) and liquid chromatography (HPLC) have been applied for their determination. HPLC is the most popular option due to the polar nature of both compounds. However, the analysis of these compounds at residue levels requires the use of preconcentration techniques.In this work we have studied different alternatives to this aim. We have evaluated the supported liquid membrane (SLM) technique where the membrane consists of an organic solution, which contains the carrier (in this case a commercial anion exchanger extractant, Aliquat 336), that impregnates a microporous polymeric support placed between two aqueous solutions: the feed solution, which initially contains the analytes, and the stripping solution, where the analytes are retained after their transport through the membrane. The best conditions were achieved with NaOH as feed solution, where the analytes are present in their anionic form and 0.1 M HCl or 0.5 M NaCl as stripping solutions indicating that the chloride ion is the responsible for the transport.Under these chemical conditions some preconcentration experiments were run using two different geometries of the membrane: a laminar membrane system (LSLM) where the stripping solution can be recirculated and a hollow fiber liquid membrane (HFSLM). The best results were obtained for the liquid membrane system in HF configuration, with concentration factors of 25 and 3 for glyphosate and AMPA, respectively, after recirculation during 24 hours of 100 ml of feed solution and 4 ml of stripping solution.A more selective technique is also studied, immobilised metal ion affinity chromatography (IMAC), which is based on the interaction between the analytes and a metal immobilised in a resin through a functional group. In this work we have immobilised palladium through the chelating group 8-hydroxyquinoline of the acrylic resin Spheron Oxine and it has been evaluated for the preconcentration of glyphosate and AMPA. 100 % adsorption has been obtained for both analytes and the recoveries are higher than 80 % and 60 % for glyphosate and AMPA, respectively, using 0.1 M HCl + 1 M NaCl as eluent. These results are compared with the results obtained working with two different resins also charged with palladium: Iontosorb Oxin, which has the same functional group but cellulose matrix, and Spheron Thiol, which a thiol functional group and acrylic matrix. The results for glyphosate are similar with all the resins tested, but for AMPA the best results are obtained with Spheron Thiol with recoveries higher than 93 %.Finally, another option studied is the coupling of two liquid chromatographic columns (LC-LC). In this work the objective is to improve the existing method for the analysis of glyphosate and AMPA in natural waters which had a LOD of 0.25 mg/l. The method consists of the pre-column derivatization with the fluorescent reagent FMOC and the analysis by LC-LC-fluorescence detection. The derivatization step has been slightly modified with the aim of decreasing the limits of quantification of glyphosate and AMPA down to 0.1 mg/l. Different water samples spiked at three concentration levels (0.1, 1, 10 mg/l) were analysed by the improved method yielding recoveries between 85-100 % with relative standard deviations lower than 8 %.Additionally, the potential of an anion-exchange resin, Amberlite&#61650; IRA-900, for preconcentration of glyphosate, previously to the derivatization step, has been investigated. In this way the LOD of the parent compound has been lowered to 0.02 mg/l.

El glifosat és un herbicida no selectiu àmpliament utilitzat en cultius agrícoles i zones no agrícoles que requereixen un control de la vegetació. Tot i la baixa toxicitat del glifosat en si mateix, la seva aplicació es realitza emprant formulacions comercials que contenen substàncies auxiliars que milloren l'eficàcia de l'herbicida, però modifiquen la toxicitat del producte final.Aquest treball s'ha centrat en la determinació de components de formulacions comercials d'herbicides i el seu comportament en el sòl. La primera part del treball s'ha dedicat al desenvolupament de mètodes d'anàlisi per a la determinació de glifosat i el seu principal metabòlit, AMPA, en matrius aquoses i sòls. A continuació s'ha desenvolupat un mètode d'anàlisi per les substàncies auxiliars addicionades freqüentment en les formulacions comercials, tensioactius no iònics. Finalment s'ha estudiat la mobilitat de l'herbicida en sòls de la zona mediterrània, incidint en els processos d'adsorció i degradació. També s'ha comparat el comportament de diversos herbicides comercials que contenen glifosat. / Glyphosate is a non-selective broad-spectrum herbicide widely used both in agriculture and in the control of vegetation in nonagricultural land. The toxicity of pure glyphosate is low but commercial formulations usually contain auxiliary substances to enhance the effectiveness of the active ingredient which modify the toxicity of the final product. The first part of this study is devoted to the development of analytical methods for the determination of glyphosate and its main metabolite, aminomethylphosphonic acid (AMPA), in aqueous and soil samples. An analytical method for the determination of non-ionic surfactants, auxiliary substances, generally added to commercial formulations, is then developed. In the second part the mobility of the herbicide in soils located in the Mediterranean area is investigated with special focus in those aspects related to the sorption and degradation processes. Finally, a comparison of the behaviour of different glyphosate-containing commercial herbicides is made.

No description available.

El objetivo general de esta tesis fue producir información científico-tecnológica básica para la implementación de un sistema integrado de control de malezas, que permita reemplazar al sistema mecánico en las plantaciones de álamo (Populus spp.) del centro-norte de la Provincia de Buenos Aires. Los trabajos se agruparon en tres líneas de investigación complementarias, en donde se abordaron grupos específicos de problemas. En la primera línea de trabajo se determinó la composición específica de la comunidad de malezas y la magnitud de su interferencia, se establecieron los niveles de control y fitotoxicidad que producen diferentes herbicidas, y se evaluaron en forma comparada los efectos sobre la supervivencia y el crecimiento del cultivo de distintos tratamientos integrados de control respecto del sistema actual. La segunda línea estudió la variación temporal de la interferencia en busca de la definición del período crítico para el control de malezas, y en la tercera línea de trabajo se evaluó el resultado económico potencial de la implementación de los cambios estudiados en el sistema de control, considerando diferentes escenarios económico-financieros, grados de incorporación de tecnología y de reemplazo de mano de obra. Las distintas líneas comprendieron experiencias en campo llevadas a cabo entre los años 1998 y 2004 en el Establecimiento Forestal "María Dolores", Partido de Alberti, Provincia de Buenos Aires (34° 50' Lat. Sur; 60° 30' Long. Oeste; 55 msnm). Los trabajos se efectuaron siguiendo una estrategia progresiva de experimentación: en una primera etapa se realizaron ensayos exploratorios y posteriormente los resultados iniciales obtenidos fueron evaluados en ensayos a escala de producción y parcelas demostrativas de 5 hectáreas de superficie.

Frequent use of phenylurea herbicide isoproturon (IPU) in agricultural fields has resulted not only in the contamination of the natural resources including soil and water but also in the adaptation of the soil microflora to its rapid degradation. However, up to now, the mechanisms underlying this microbial adaptation are not well elucidated. The aim of this study was to explore the processes and factors implicated in IPU degradation from the agricultural field to the genes coding for catabolic genes. The study carried out at the experimental field of Epoisses cropped with a winter wheat / barley / rape seed crop rotation indicated that as a result of its periodically repeated use, the soil microflora adapted to IPU mineralization activity. Further analysis using exploratory and geostatistical tools demonstrated the existence of spatial variability in IPU mineralization activity at the field scale which was correlated not only with several soil physico-chemical parameters like organic matter content, CEC and C/N ratio but also with the pesticide application plan over a three year crop rotation. In order to get further insight into underlying mechanisms, an IPU mineralizing bacterial culture and strain Sphingomonas sp. SH were isolated through enrichment cultures performed from two different adapted soils. Both had the catabolic activities highly specific for the mineralization of IPU and its metabolites but none of other structurally related phenylurea herbicides. IPU metabolic activity of both the mixed culture and the strain SH was found to be affected by pH with optimal activity taking place at pH 7.5. Based on the accumulation of different known metabolites during mineralization kinetics, IPU metabolic pathway was proposed to be initiated by two successive demethylations, followed by cleavage of the urea side chain resulting in the accumulation of 4-isopropylaniline, and ultimately the mineralization of the phenyl ring. In order to identify the genes involved in IPU degradation, BAC clone library was established from the genomic DNA of the bacterial culture. Although, the functional screening did not yield in identifying any BAC clone able to degrade IPU or its known metabolites, the PCR based screening led us to identify a cat gene cluster involved in ortho-cleavage of the phenyl ring of catechol through beta-ketoadipate pathway. Based on this finding, it was hypothesized that phenyl ring of 4-isopropylaniline formed during IPU transformation might be mineralized through ortho-cleavage of catechol. This finding allowed us to propose the lower IPU metabolic pathway which was not yet described.