<i>Pseudomonas fluorescens</i> BRG100 produces secondary metabolites with herbicidal activity to the grass weeds wild oat, Avena fatua, and green foxtail, Setaria viridis. The green fluorescence protein (gfp) gene was introduced into P. fluorescens BRG100 from Escherichia coli S17-1¥ë via a Tn5 mini transposon suicide vector system. Colony morphology, growth rate in liquid media, weed biocontrol efficacy (plant growth pouch), carbon utilization (Biolog GN) and root colonization of green foxtail by several P. fluorescens BRG100gfp transformants were determined to be the same as the wild type. <i>Pseudomonas fluorescens</i> BRGgfp-15 was found to be most similar to the wild-type in all of the above characteristics and was thus used in subsequent experiments. Note: all strains of Pseudomonas fluorescens will be referred to by only their strain throughout (ie. BRGgfp-15 and BRG100). <p>It was determined by population dynamics per section of root with spiral plating on culture medium, epi-fluorescence and confocal microscopy that BRGgfp-15 colonized all areas of the root, but showed a preference for the proximal 1/3 section and the seed. In the proximal section the mean number of viable cells per gram dry weight was log109.06 and log109.31, when applied as liquid inoculum and as the pesta granular formulation, respectively. With liquid inoculum there was only log107.53 viable cells/g in the middle 1/3 section and log107.01 viable cells/g in the distal 1/3 section. The number of viable cells/g with pesta granules was log107.61 and log107.34, for the middle and distal sections, respectively. The root hairs, root tip, and ventral portion of the seed were all areas of heavy colonization relative to the other areas of the root. <p>Survival of BRGgfp-15 in the pesta formulation was examined in 2 soil types, clay and clay loam, in a thermogradient plate apparatus by a factorial randomized design complete block experiment. The experiment included: 3-12 hour diurnal temperature regimes: 5-15¨¬C, 15-25¨¬C, and 25-35¨¬C and 3 moisture levels: 25, 50 and 75% of soil moisture holding capacity. Sampling was carried out after 0, 14, 28 and 42 days. The highest numbers of viable BRGgfp-15 cells/g were found in the pesta granules in soil subjected to the lowest diurnal temperature regime and moisture content. The lowest numbers of viable cells/g were found in the pesta granules incubated in the highest diurnal temperature and moisture. This suggests lower soil temperature and moisture enhances survival of BRGgfp-15 in pesta and/ or higher soil temperature and moisture enhances the release and dissemination of BRGgfp-15 from pesta granules. When subjected to a 5-15¨¬C-temperature regime the number of viable cells/g was log109.80. When subjected to 15-25¨¬C the viable cells/g was log108.96 and with 25-35¨¬C it was log107.33. The mean number of viable cells/g was log109.36, log108.86, and log107.87, for 25, 50, and 75% soil moisture holding capacity, respectively. There was also a significantly higher number of viable cells/g in the clay soil collected from Saskatoon, log109.00, as compared to the clay loam soil collected from Scott, which was log108.40. <p>These results suggest that Pseudomonas fluorescens BRG100 has considerable potential as a bioherbicide because of its successful root colonization of green foxtail and wheat. <i>Pseudomonas fluorescens</i> BRGgfp-15 survived well under various environmental conditions when formulated into pesta granules, proving the pesta formulation was an excellent formulation. In addition, gfp was shown to be an excellent conservative marker for monitoring the root colonization and survival of <i>P. fluorescens</i> BRG100.

Across Canada, and around the world, very large amounts of pesticides are produced and applied to agricultural crops each year. Although pesticide usage is declining, they are still a necessary part of industrial agriculture. Numerous pesticides have been quantified in the atmosphere, at high levels near regions of use and at lower, but still significant levels in remote regions. Some of the most persistent pesticides have been banned, but others continue to be used despite their persistence and potential for long-range transport (LRT). We have applied and refined an XAD-2 resin-based passive air sampler (PAS) to study the concentrations of pesticides in the atmosphere. A set of laboratory experiments measured the equilibria sorption coefficients for chemicals on XAD-2 resin, allowing the determination of a new predictive equation for equilibria sorption coefficients, and thus interpretation of the range of applicability of both XAD-based PAS and active air samplers (AAS). A set of field experiments were performed to compare the data obtained by both PAS and AAS, and to study the temporal trends of a wide range of pesticides in an agricultural area of southern Ontario. Because it is now apparent that XAD-PAS sampling rates can vary between compounds and with temperature, we also determined new compound-specific sampling rates for pesticides in the XAD-PAS. The XAD-PAS were deployed in two transects across Canada, one from the Great Lakes region to the Canadian Arctic, and one across southern British Columbia in four different mountain regions and at different elevations. The air concentrations of current-use pesticides were correlated with regions of their use in both transects. The variation of air concentration with elevation was correlated with local, ground-level sources in British Columbia. The LRT of pesticides was determined from the north-south transect, and correlated to their atmospheric half-lives. Historic-use pesticides such as hexachlorobenzene and hexachlorocyclohexane were found to have relatively uniform distributions in the Canadian atmosphere, while further evidence of α-hexachlorocyclohexane evaporation from oceans was observed in both transects.

Across Canada, and around the world, very large amounts of pesticides are produced and applied to agricultural crops each year. Although pesticide usage is declining, they are still a necessary part of industrial agriculture. Numerous pesticides have been quantified in the atmosphere, at high levels near regions of use and at lower, but still significant levels in remote regions. Some of the most persistent pesticides have been banned, but others continue to be used despite their persistence and potential for long-range transport (LRT). We have applied and refined an XAD-2 resin-based passive air sampler (PAS) to study the concentrations of pesticides in the atmosphere. A set of laboratory experiments measured the equilibria sorption coefficients for chemicals on XAD-2 resin, allowing the determination of a new predictive equation for equilibria sorption coefficients, and thus interpretation of the range of applicability of both XAD-based PAS and active air samplers (AAS). A set of field experiments were performed to compare the data obtained by both PAS and AAS, and to study the temporal trends of a wide range of pesticides in an agricultural area of southern Ontario. Because it is now apparent that XAD-PAS sampling rates can vary between compounds and with temperature, we also determined new compound-specific sampling rates for pesticides in the XAD-PAS. The XAD-PAS were deployed in two transects across Canada, one from the Great Lakes region to the Canadian Arctic, and one across southern British Columbia in four different mountain regions and at different elevations. The air concentrations of current-use pesticides were correlated with regions of their use in both transects. The variation of air concentration with elevation was correlated with local, ground-level sources in British Columbia. The LRT of pesticides was determined from the north-south transect, and correlated to their atmospheric half-lives. Historic-use pesticides such as hexachlorobenzene and hexachlorocyclohexane were found to have relatively uniform distributions in the Canadian atmosphere, while further evidence of α-hexachlorocyclohexane evaporation from oceans was observed in both transects.

<i>Pseudomonas fluorescens</i> BRG100 produces secondary metabolites with herbicidal activity to the grass weeds wild oat, Avena fatua, and green foxtail, Setaria viridis. The green fluorescence protein (gfp) gene was introduced into P. fluorescens BRG100 from Escherichia coli S17-1¥ë via a Tn5 mini transposon suicide vector system. Colony morphology, growth rate in liquid media, weed biocontrol efficacy (plant growth pouch), carbon utilization (Biolog GN) and root colonization of green foxtail by several P. fluorescens BRG100gfp transformants were determined to be the same as the wild type. <i>Pseudomonas fluorescens</i> BRGgfp-15 was found to be most similar to the wild-type in all of the above characteristics and was thus used in subsequent experiments. Note: all strains of Pseudomonas fluorescens will be referred to by only their strain throughout (ie. BRGgfp-15 and BRG100). <p>It was determined by population dynamics per section of root with spiral plating on culture medium, epi-fluorescence and confocal microscopy that BRGgfp-15 colonized all areas of the root, but showed a preference for the proximal 1/3 section and the seed. In the proximal section the mean number of viable cells per gram dry weight was log109.06 and log109.31, when applied as liquid inoculum and as the pesta granular formulation, respectively. With liquid inoculum there was only log107.53 viable cells/g in the middle 1/3 section and log107.01 viable cells/g in the distal 1/3 section. The number of viable cells/g with pesta granules was log107.61 and log107.34, for the middle and distal sections, respectively. The root hairs, root tip, and ventral portion of the seed were all areas of heavy colonization relative to the other areas of the root. <p>Survival of BRGgfp-15 in the pesta formulation was examined in 2 soil types, clay and clay loam, in a thermogradient plate apparatus by a factorial randomized design complete block experiment. The experiment included: 3-12 hour diurnal temperature regimes: 5-15¨¬C, 15-25¨¬C, and 25-35¨¬C and 3 moisture levels: 25, 50 and 75% of soil moisture holding capacity. Sampling was carried out after 0, 14, 28 and 42 days. The highest numbers of viable BRGgfp-15 cells/g were found in the pesta granules in soil subjected to the lowest diurnal temperature regime and moisture content. The lowest numbers of viable cells/g were found in the pesta granules incubated in the highest diurnal temperature and moisture. This suggests lower soil temperature and moisture enhances survival of BRGgfp-15 in pesta and/ or higher soil temperature and moisture enhances the release and dissemination of BRGgfp-15 from pesta granules. When subjected to a 5-15¨¬C-temperature regime the number of viable cells/g was log109.80. When subjected to 15-25¨¬C the viable cells/g was log108.96 and with 25-35¨¬C it was log107.33. The mean number of viable cells/g was log109.36, log108.86, and log107.87, for 25, 50, and 75% soil moisture holding capacity, respectively. There was also a significantly higher number of viable cells/g in the clay soil collected from Saskatoon, log109.00, as compared to the clay loam soil collected from Scott, which was log108.40. <p>These results suggest that Pseudomonas fluorescens BRG100 has considerable potential as a bioherbicide because of its successful root colonization of green foxtail and wheat. <i>Pseudomonas fluorescens</i> BRGgfp-15 survived well under various environmental conditions when formulated into pesta granules, proving the pesta formulation was an excellent formulation. In addition, gfp was shown to be an excellent conservative marker for monitoring the root colonization and survival of <i>P. fluorescens</i> BRG100.

Cities are sources of persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), to surrounding regions and beyond. A spatially resolved, (5×5 km2), dynamic contaminant fate model named Spatially Oriented or SO-MUM was developed by coupling the fugacity based Multimedia Urban Model (MUM) (Diamond et al., 2001; Diamond et al., 2010c) and the Boundary Layer Forecast Model and Air Pollution Prediction System (BLFMAPS) which was developed at Environment Canada (Daggupaty et al., 2006). MUM was updated to contain a revised surface film sub-model which takes into account the dynamic nature of surface films. SO-MUM was illustrated by application to the City of Toronto, Canada. Spatially resolved air emissions of Σ88PCB were estimated to be ~230 (40-480) kg y-1, 280 (50-580) g y-1 km-2, and 90 (16-190) mg y-1 capita-1 and Σ26PBDE were estimated to be 28 (6-63) kg y-1, 34 (7-77) g y-1 km-2 and 11 (2-25) mg y-1 capita-1. These emissions were back-calculated from measured air concentrations and spatial chemical mass inventories yielding emission rates per mass inventory of 0.4 (0.05-1.6) and 0.1 (0.01-0.7) g kg-1inventory y-1, for Σ88PCBs and Σ26PBDEs, respectively. Approximately 30% and 16% of PCB and PBDE emissions emanate from the city’s downtown. Air advection accounted for ~95% (PCB) and ~70% (PBDE) of total air emission losses with the remaining balance depositing to the city. The metric “Urban Travel Distance” or UTD was introduced for quantifying the extent of an urban plume resulting from spatially heterogeneous emissions. For PCBs and PBDEs the UTDs were ~25 and ~30 km. The updated surface film sub-model indicated that films “bounce” higher vapor pressure semi-volatile organic compounds (SVOCs) back into the air but they act as a transient sink from air for lower vapor pressure SVOCs, thereby facilitating transport to surface waters. Model calculations suggest that if the PCB inventory is reduced, volatilization from near-shore Lake Ontario will become a net source of PCBs to air, but that neither near-shore Lake Ontario nor soil would become a significant volatilization PBDE source to air.

Cities are sources of persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), to surrounding regions and beyond. A spatially resolved, (5×5 km2), dynamic contaminant fate model named Spatially Oriented or SO-MUM was developed by coupling the fugacity based Multimedia Urban Model (MUM) (Diamond et al., 2001; Diamond et al., 2010c) and the Boundary Layer Forecast Model and Air Pollution Prediction System (BLFMAPS) which was developed at Environment Canada (Daggupaty et al., 2006). MUM was updated to contain a revised surface film sub-model which takes into account the dynamic nature of surface films. SO-MUM was illustrated by application to the City of Toronto, Canada. Spatially resolved air emissions of Σ88PCB were estimated to be ~230 (40-480) kg y-1, 280 (50-580) g y-1 km-2, and 90 (16-190) mg y-1 capita-1 and Σ26PBDE were estimated to be 28 (6-63) kg y-1, 34 (7-77) g y-1 km-2 and 11 (2-25) mg y-1 capita-1. These emissions were back-calculated from measured air concentrations and spatial chemical mass inventories yielding emission rates per mass inventory of 0.4 (0.05-1.6) and 0.1 (0.01-0.7) g kg-1inventory y-1, for Σ88PCBs and Σ26PBDEs, respectively. Approximately 30% and 16% of PCB and PBDE emissions emanate from the city’s downtown. Air advection accounted for ~95% (PCB) and ~70% (PBDE) of total air emission losses with the remaining balance depositing to the city. The metric “Urban Travel Distance” or UTD was introduced for quantifying the extent of an urban plume resulting from spatially heterogeneous emissions. For PCBs and PBDEs the UTDs were ~25 and ~30 km. The updated surface film sub-model indicated that films “bounce” higher vapor pressure semi-volatile organic compounds (SVOCs) back into the air but they act as a transient sink from air for lower vapor pressure SVOCs, thereby facilitating transport to surface waters. Model calculations suggest that if the PCB inventory is reduced, volatilization from near-shore Lake Ontario will become a net source of PCBs to air, but that neither near-shore Lake Ontario nor soil would become a significant volatilization PBDE source to air.

The risk associated with the application and co-occurrence of atrazine and sulfentrazone, two herbicides applied to a corn and soybean rotational field, was evaluated in the current study. Peak field concentrations were found in the soil matrix, with atrazine and sulfentrazone values of 144 ng/g dry weight (dw), and 318 ng/g dw, respectively; however, due to the physicochemical properties of the compounds, the two herbicides were also transported to field water matrices. The highest mean runoff water concentrations for atrazine and sulfentrazone were 4.72 µg/L and 10.3 µg/L, respectively. A direct spray event of atrazine to the runoff water sampler caused concentrations as high as 1.6 mg/L, effectively becoming a worst case scenario concentration. Individual and mixture laboratory bioassays were also conducted to determine the effects of atrazine and sulfentrazone on the survival of D. magna, and P. promelas. Sub-lethal effects including germination of L. sativa, and growth of P. promelas, S. capricornutum and L. minor were also evaluated. Results showed that S. capricornutum and L. minor were the most susceptible non-target species tested, and synergistic effects were observed for both species when equipotent mixtures were tested. Margin of safety of 10% (MOS10) values were calculated for each species using field concentrations and bioassay benchmark concentrations. Atrazine MOS10 values, calculated with environmental concentrations not including the direct spray event, were 0.83 and 0.10 for S. capricornutum and L. minor, respectively. The MOS10 value for sulfentrazone effects on S. capricornutum was 0.31, and effects on L. minor was 1.39. There was a slight risk to S. capricornutum and L. minor growth associated with exposure to atrazine and sulfentrazone in an agricultural field. Although the co-occurrence of atrazine and sulfentrazone was observed, and synergistic effects were observed in the equipotent binary mixture bioassays for S. capricornutum and L. minor, it is believed that there is minimal increase in risk potential due to the co-occurrence, because field concentrations do not proportionally mimic the concentrations that produced synergism in the plant species.

Gallium arsenide (GaAs), cadmium selenide (CdSe), and cadmium telluride (CdTe) are semiconductor materials with remarkable opto-electronic properties that make them suitable for a wide variety of applications including, light emitting diodes (LEDs), mobile phones, tablets, and solar panels. Due to the growing demand and the short lifespan of these electronic devices, a remarkable amount of electronic waste (e-waste) has been produced in the last decades. An important fate of e-waste is landfill disposal; therefore, there is an increasing concern about the release of toxic elements into the landfill environment and the potential risks for human health and the environment. Among the elements constituting GaAs, CdTe, and CdSe, tellurium (Te) has gained increasing attention in recent years. Tellurium is a scarce element on the earth’s crust, and a shortage in its supply might compromise the development of new advanced technology, particularly in the energy and defense fields. For these reasons, the US Department of Energy and the European Union regard Te as a critical element, and have urged the need to develop efficient and cost-effective processes to recover Te from waste streams. This thesis dissertation explored different aspects related to the fate and impact of the widely used semiconductor materials, GaAs, CdSe and CdTe in municipal mixed solid waste (MSW) landfills. Furthermore, it investigated the removal of the Te oxyanions, tellurite (Teᴵⱽ, TeO₃²⁻) and tellurate (Teⱽᴵ, TeO₄²⁻), from aqueous streams and the recovery of this strategic metalloid as biogenic, elemental tellurite (Te⁰) nanoparticles (NPs). In the first part this work, the dissolution of GaAs was evaluated under a range of redox conditions, pH levels, ionic strength, and the presence of organic constituents commonly found in landfills. Our results indicated that aerobic conditions and mildly alkaline pH conditions favor the dissolution and release of high levels of soluble arsenic (As) and gallium (Ga) to the synthetic leaching solutions. The rate of As and Ga dissolution in long-term exposure experiments was initially constant but later progressively decreased due to the formation of a passivating layer on the surface of GaAs. The leaching behavior of CdSe and CdTe was also investigated under different pH and redox conditions in solutions simulating landfill leachates. CdTe and CdSe were subjected to two different standardized leaching tests, the federal Toxicity Characteristic Leaching Procedure (TCLP) and the California Waste Extraction Test (WET). CdTe showed a very high leaching potential in both tests and the concentrations of Cd released were 1500- and 260-times higher than the regulatory limit (1 mg Cd L⁻¹), respectively. In contrast, CdSe was relatively stable and dissolved selenium (Se) in both leaching tests was below the regulatory threshold (1 mg Se L⁻¹). Tests performed under different pH and redox conditions confirmed a marked enhancement in CdTe and CdSe dissolution both under acidic pH and aerobic conditions, which is consistent with thermodynamic predictions. Due to the high leaching potential observed for CdTe in the previous batch experiments, leaching studies were designed to investigate the potential release of soluble Cd and Te from a commercially available CdTe thin-film solar panel under different chemical and biogeochemical conditions commonly found in landfills. The solar panel was subjected to two standardized batch leaching tests (i.e., TCLP and WET), and to a continuous column test designed to investigate the dissolution of CdTe under conditions simulating the acidic- and the methanogenic circumneutral phases of a MSW landfill. A negligible amount of Cd and Te was measured in the synthetic leachate of both batch tests. On the other hand, a significant amount of Cd and Te was released from the panel to the synthetic leachate of the column simulating an acid landfill after 30 days (73% and 21% of the total Cd and Te, respectively). In contrast, the amount of Cd or Te detected in the effluent of the column operated at circumneutral pH values was negligible. The marked difference in the leaching behavior of CdTe in both columns is related to the different aqueous pH and redox conditions promoted by the microbial communities in the columns. The microbial toxicity of the soluble species that can be released from CdTe and CdSe was also assessed as a part of this work. The toxicity of cadmium (Cdᴵᴵ), selenite (Seᴵⱽ), selenate (Seⱽᴵ), Teᴵⱽ, and Teⱽᴵ was evaluated in bioassays with different microbial targets, including acetoclastic and hydrogenotrophic methanogenic populations in a mixed microbial culture, similar to those involved in the stabilization of organic waste stabilization in a landfill, and the bioluminescent marine bacterium, 𝐴𝑙𝑖𝑖𝑣𝑖𝑏𝑟𝑖𝑜 𝑓𝑖𝑠𝑐ℎ𝑒𝑟𝑖 (Microtox® test). The acetoclastic methanogens were most sensitive to the presence of the various soluble species, with the toxicity decreasing in the following order: Cdᴵᴵ, Teᴵⱽ, Teⱽᴵ, Seᴵⱽ, while Seⱽᴵ was only toxic at non-environmentally relevant concentration. Hydrogenotrophic methanogens were highly inhibited by Cdᴵᴵ and Seᴵⱽ, but Teᴵⱽ and Teⱽᴵ only had a moderate toxic impact. The bacterium 𝐴. 𝑓𝑖𝑠𝑐ℎ𝑒𝑟𝑖 was very sensitive to inhibition by Cdᴵᴵ and Seᴵⱽ, and Teᴵⱽ. In the last part of this work, the potential recovery of insoluble, elemental Te⁰ NPs from aqueous solutions containing soluble Teᴵⱽ or Teⱽᴵ was investigated in batch- and continuous flow bioreactors inoculated with a methanogenic granular mixed culture. In the batch experiments, the capacity of the culture to catalyze the reduction of the Te oxyanions and to produce Te⁰ NPs internally and externally to the cells was demonstrated. The granular sludge was found to contain enough endogenous substrates to provide the electron equivalents required to reduce both Te oxyanions and the reduction rates were only modestly increased by an exogenous electron-donor (e-donor) such as H₂. The effect of several redox mediators (RM), namely, anthraquinone-2,6-disulfonate (AQDS), hydroxocobalamin, riboflavin, and lawsone, was also tested. Riboflavin and lawsone caused a remarkable increase of the rate of Teᴵⱽ and Teⱽᴵ reduction, respectively, and also enhanced the fraction of Te recovered as extracellular Te⁰ NPs. The morphology and localization of the Te⁰ NPs were also impacted by the presence of a particular RM and e-donor in the system, suggesting that NP production can be tailored for a particular application. Finally, the feasibility of utilizing upflow anaerobic sludge bed (UASB) bioreactors to reduce Teᴵⱽ oxyanions to non-toxic Te⁰ NPs was also investigated. Two reactors were supplied with ethanol as the external e-donor source to promote the biological reduction of Teᴵⱽ. Riboflavin, a redox mediator, was supplied to one of the reactors to enhance Teᴵⱽ bioreduction. Continuous formation of Te⁰ NPs using an UASB was found to be feasible and remarkably improved by addition of riboflavin at the low Teᴵⱽ:riboflavin molar ratio of 4:1. This flavonoid enhanced the conversion rate of Teᴵⱽ and reduced the toxic impact of Teᴵⱽ towards the methanogenic consortium. Overall, the evidence found in this work indicates that recycling of decommissioned devices containing GaAs, CdTe, or CdSe is desirable to prevent the potential environmental release of toxic metals and metalloids in MSW landfills, but also to allow the recovery of critical resources. Microbial processes offer potential for the removal and recovery of soluble metals and metalloid ions leached from decommissioned semiconductor materials. In particular, this study demonstrated the feasibility of utilizing continuous UASB bioreactors for the removal of Teᴵⱽ from aqueous streams and the recovery of this valuable metalloid as biogenic Te⁰ NPs.

Um novo herbicida da classe das sulfonamida-triazolopirimidinas do grupo dos herbicidas inibidores da síntese do acetolactato (ALS) encontra-se em desenvolvimento. Trata-se de um herbicida ionizável, com caráter ácido fraco (pKa = 4,67). Sua solubilidade em água depende do pH do meio, trata-se de uma molécula hidroliticamente estável, sendo bastante suscetível à fotodegradação em meio aquoso. A fotodegradação em solo não é significativa. Neste estudo, avaliaram-se os potenciais de sorção, lixiviação e dissipação deste herbicida em quatro solos brasileiros: Gleissolo Melânico Alumínico típico (GMa), Latossolo Vermelho Distroférrico típico (LVdf), Neossolo Quartzarênico órtico típico (RQ) e Argissolo Vermelho eutroférrico chernossólico (PV). No estudo de sorção, as isotermas foram ajustadas através do modelo de Freundlich e os valores dos coeficientes de sorção (Kd) variaram de 0,5 a 22,4 mL g-1 indicando um potencial de sorção baixo a moderado. No estudo de mobilidade, nenhuma radioatividade foi observada nos lixiviados coletados até 48 horas nos solos GMa, LVdf e PV, no solo RQ detectou-se 2 % do aplicado. Os resultados de mobilidade comparativos sugerem que o herbicida seja classificado como moderadamente móvel pelo critério do Fator de Mobilidade Relativa (FMR) em todos os solos estudados. No estudo de dissipação, a taxa de transformação do herbicida em condições aeróbicas além da natureza e taxa de formação e declínio de produtos de transformação do herbicida foram acessados. Um modelo exponencial de primeira ordem foi utilizado para ajustar a dissipação do herbicida nos solos. A meia-vida do herbicida foi de 22, 15, 110 e 39 nos solos GMa, LVdf, RQ e PV, respectivamente. Uma avaliação de risco ambiental inicial do herbicida foi acessada pelo uso do método dos quocientes (RQ risk quotient), sendo risco = exposição/efeito. A exposição é representada pela Concentração Ambiental Esperada (CAE) e foi avaliada nos compartimentos ambientais solo, águas superficiais e águas subterrâneas. Os cálculos de CAE foram obtidos por avaliação de cenários simples do tipo pior caso nos diferentes compartimentos e pelo emprego dos modelos matemáticos GENEEC e SCIGROW para águas superficiais e subterrâneas, respectivamente. Na estimativa do efeito, usou-se os valores limite (endponts, exemplos: EC50, NOEC) disponíveis para diferentes organismos representantes dos diferentes compartimentos ambientais estudados. O resultado do quociente exposição/efeito foi comparado com os níveis de preocupação (LOC level of concern) empregados pelo EPA para avaliação do potencial risco do uso deste herbicida para os diferentes organismos representativos dos diferentes compartimentos ambientais estudados. Assumindo o pior cenário (menor valor de Kd e maior valor de DT50), as estimativas das CAEs foram baixas e iguais a 0,024 mg kg-1 no solo, a 0,0008 mg L-1 na água superficial e a 0,04 \'mü\' L-1 na água subterrânea. Os valores de RQ obtidos (< 1 e inferiores aos respectivos LOCs) indicaram baixo potencial de risco do uso deste herbicida para os diferentes organismos, representativos dos diversos compartimentos ambientais estudados / A new active ingredient of the triazolopyrimidine sulfonamide herbicide class from the ALS group is under development. This is an ionizable herbicide with weakly acidic behavior (pKa = 4.67). Its solubility in water depends on pH, it is a hydrolytically stable molecule, being highly susceptible to photodegradation in aqueous medium. The photodegradation in soil is not significant. This study evaluated the potential of sorption, leaching and dissipation of this herbicide in four Brazilian soils: Gleissolo Melânico Alumínico típico (GMa), Latossolo Vermelho Distroférrico típico (LVdf), Neossolo Quartzarênico órtico típico (RQ) e Argissolo Vermelho eutroférrico chernossólico (PV). In the study of sorption isotherms were fitted using the Freundlich model and the values of sorption coefficients (Kd) ranged from 0.5 to 22.4 g mL-1 indicating a potential low to moderate sorption. In the study of mobility, no radioactivity was observed in the leachate collected until 48 hours in soils GMa, LVdf and PV, in the soil RQ was detected about 2% of applied radioactivity. The results of comparative mobility suggest that the herbicide is classified as moderately mobile by the criterion of Relative Mobility Factor (FMR) in all soils. In the study of dissipation, the rate of transformation of the herbicide under aerobic conditions and rate of formation and decline of transformation products of herbicide were accessed. A first order exponential model was used to adjust the dissipation of the herbicide in soils. The half-life of the herbicide was 22, 15, 110 and 39 days in soils GMa, LVdf, RQ and PV, respectively. An initial environmental risk assessment of the herbicide was accessed by using the method of quotient (RQ - risk quotient), RQ = exposure / effect. The exposure is represented by the Expected Environmental Concentration (EEC) and was evaluated in the environmental compartments soil, surface water and groundwater. EEC calculations were obtained by assessing simple scenarios such as \"worst case\" in the different compartments and the use of mathematical models GENEEC and SCIGROW to surface and groundwater assessments, respectively. In estimating the effect, endponts (examples: EC50, NOEC) available for different organisms representative from the different environmental compartments studied were used. The result of the quotient exposure / effect was compared to the \"levels of concern (LOC - level of concern) employed by the EPA to assess the potential risk from use of this herbicide for different organisms representing different environmental compartments studied. Assuming the worst case scenario (lower Kd value and higher value of DT50), the estimates of EECs were low and equal to 0.024 mg kg-1 soil, 0.0008 mg L-1 in surface water and 0.04 \'mü\' L-1 in the groundwater. The RQ values obtained (< 1 and below the respective LOCs) indicated low potential risk from use of this herbicide for different organisms, representative from different environmental compartments studied

Um novo herbicida da classe das sulfonamida-triazolopirimidinas do grupo dos herbicidas inibidores da síntese do acetolactato (ALS) encontra-se em desenvolvimento. Trata-se de um herbicida ionizável, com caráter ácido fraco (pKa = 4,67). Sua solubilidade em água depende do pH do meio, trata-se de uma molécula hidroliticamente estável, sendo bastante suscetível à fotodegradação em meio aquoso. A fotodegradação em solo não é significativa. Neste estudo, avaliaram-se os potenciais de sorção, lixiviação e dissipação deste herbicida em quatro solos brasileiros: Gleissolo Melânico Alumínico típico (GMa), Latossolo Vermelho Distroférrico típico (LVdf), Neossolo Quartzarênico órtico típico (RQ) e Argissolo Vermelho eutroférrico chernossólico (PV). No estudo de sorção, as isotermas foram ajustadas através do modelo de Freundlich e os valores dos coeficientes de sorção (Kd) variaram de 0,5 a 22,4 mL g-1 indicando um potencial de sorção baixo a moderado. No estudo de mobilidade, nenhuma radioatividade foi observada nos lixiviados coletados até 48 horas nos solos GMa, LVdf e PV, no solo RQ detectou-se 2 % do aplicado. Os resultados de mobilidade comparativos sugerem que o herbicida seja classificado como moderadamente móvel pelo critério do Fator de Mobilidade Relativa (FMR) em todos os solos estudados. No estudo de dissipação, a taxa de transformação do herbicida em condições aeróbicas além da natureza e taxa de formação e declínio de produtos de transformação do herbicida foram acessados. Um modelo exponencial de primeira ordem foi utilizado para ajustar a dissipação do herbicida nos solos. A meia-vida do herbicida foi de 22, 15, 110 e 39 nos solos GMa, LVdf, RQ e PV, respectivamente. Uma avaliação de risco ambiental inicial do herbicida foi acessada pelo uso do método dos quocientes (RQ risk quotient), sendo risco = exposição/efeito. A exposição é representada pela Concentração Ambiental Esperada (CAE) e foi avaliada nos compartimentos ambientais solo, águas superficiais e águas subterrâneas. Os cálculos de CAE foram obtidos por avaliação de cenários simples do tipo pior caso nos diferentes compartimentos e pelo emprego dos modelos matemáticos GENEEC e SCIGROW para águas superficiais e subterrâneas, respectivamente. Na estimativa do efeito, usou-se os valores limite (endponts, exemplos: EC50, NOEC) disponíveis para diferentes organismos representantes dos diferentes compartimentos ambientais estudados. O resultado do quociente exposição/efeito foi comparado com os níveis de preocupação (LOC level of concern) empregados pelo EPA para avaliação do potencial risco do uso deste herbicida para os diferentes organismos representativos dos diferentes compartimentos ambientais estudados. Assumindo o pior cenário (menor valor de Kd e maior valor de DT50), as estimativas das CAEs foram baixas e iguais a 0,024 mg kg-1 no solo, a 0,0008 mg L-1 na água superficial e a 0,04 \'mü\' L-1 na água subterrânea. Os valores de RQ obtidos (< 1 e inferiores aos respectivos LOCs) indicaram baixo potencial de risco do uso deste herbicida para os diferentes organismos, representativos dos diversos compartimentos ambientais estudados / A new active ingredient of the triazolopyrimidine sulfonamide herbicide class from the ALS group is under development. This is an ionizable herbicide with weakly acidic behavior (pKa = 4.67). Its solubility in water depends on pH, it is a hydrolytically stable molecule, being highly susceptible to photodegradation in aqueous medium. The photodegradation in soil is not significant. This study evaluated the potential of sorption, leaching and dissipation of this herbicide in four Brazilian soils: Gleissolo Melânico Alumínico típico (GMa), Latossolo Vermelho Distroférrico típico (LVdf), Neossolo Quartzarênico órtico típico (RQ) e Argissolo Vermelho eutroférrico chernossólico (PV). In the study of sorption isotherms were fitted using the Freundlich model and the values of sorption coefficients (Kd) ranged from 0.5 to 22.4 g mL-1 indicating a potential low to moderate sorption. In the study of mobility, no radioactivity was observed in the leachate collected until 48 hours in soils GMa, LVdf and PV, in the soil RQ was detected about 2% of applied radioactivity. The results of comparative mobility suggest that the herbicide is classified as moderately mobile by the criterion of Relative Mobility Factor (FMR) in all soils. In the study of dissipation, the rate of transformation of the herbicide under aerobic conditions and rate of formation and decline of transformation products of herbicide were accessed. A first order exponential model was used to adjust the dissipation of the herbicide in soils. The half-life of the herbicide was 22, 15, 110 and 39 days in soils GMa, LVdf, RQ and PV, respectively. An initial environmental risk assessment of the herbicide was accessed by using the method of quotient (RQ - risk quotient), RQ = exposure / effect. The exposure is represented by the Expected Environmental Concentration (EEC) and was evaluated in the environmental compartments soil, surface water and groundwater. EEC calculations were obtained by assessing simple scenarios such as \"worst case\" in the different compartments and the use of mathematical models GENEEC and SCIGROW to surface and groundwater assessments, respectively. In estimating the effect, endponts (examples: EC50, NOEC) available for different organisms representative from the different environmental compartments studied were used. The result of the quotient exposure / effect was compared to the \"levels of concern (LOC - level of concern) employed by the EPA to assess the potential risk from use of this herbicide for different organisms representing different environmental compartments studied. Assuming the worst case scenario (lower Kd value and higher value of DT50), the estimates of EECs were low and equal to 0.024 mg kg-1 soil, 0.0008 mg L-1 in surface water and 0.04 \'mü\' L-1 in the groundwater. The RQ values obtained (< 1 and below the respective LOCs) indicated low potential risk from use of this herbicide for different organisms, representative from different environmental compartments studied