The natural breakdown of three pesticides on the UK Red List (dieldrin, simazine and trifluralin) in water and soil varied with environmental conditions. In both sterile and unsterile water, trifluralin was degraded to some extent at 20 and 30°C. In contrast, dieldrin and simazine were stable over the 42 days incubation period. A gradient HPLC method was developed for the simultaneous quantification of the three pesticides in soil. In field capacity soil mixtures of the three pesticides (5 and 10 ppm) showed a similar stability with limited degradation at 20°C but increased rates of degradation at 30°C. At the higher concentration the pesticides naturally degraded at a slower rate. Simazine and trifluralin degradation was significantly enhanced with increasing temperature from 20 to 30°C. Water potential (field capacity~ -0.065 MPa~ and - 0.28 MPa) had little effect on the natural breakdown rate of dieldrin. Simazine showed a greater breakdown in the mid-wetness soil~ while trifluralin was degraded rapidly in the field capacity soil, but not at all in the driest treatment over the 70 day experimental period. In vitro studies on solid agar media overlayed with cellophane showed that of four fungi examined~ Trametes cingulata, Trametes socotrana (tropical species) and Phanerochaete chrysosporium and Polystictus versicolor (temperate species) all except P.chrysosporium were able to grow in the presence of 5 ppm of any of the three pesticides at 20 and 30°C, with the latter only growing at 30°C. At 10 ppm concentration P. chrysosporium did not grow, regardless of temperature or time of incubation (up to 56 days). HPLC was used to quantify the temporal rates of degradation in the solid agar media and this showed that P. versicolor and T. socotrana were very effective at breaking down the three pesticides, at 20 and 30°C. The chosen fungi were grown on chopped straw as a carrier and incorporated into soil microcosms in the ratio of 1:10 containing mixtures of the three pesticides (5, 10 ppm) at 20 and 30°C, and subsequently under different water potential regimes at 20°C only, over periods of 70 days. P. versicolor alone significantly increased breakdown of 5 ppm dieldrin by 26% over untreated controls, while simazine breakdown was increased by 16%. However, for simazine at 30°C there was no difference between temporal rates of natural breakdown and those containing fungal inocula, regardless of concentration. With 5 ppm trifluralin, a maximum breakdown in untreated soil was 67% after 70 days. By contras~ this pesticide was undetectable after 28 days in the presence of the inoculant P . versicolor. This increased to 42 days where a mixture of the two fungi were used. Generally the mixture of fungi used in this study were not as effective in bioremediation of these pesticides as a single species. Field capacity soil appeared to be the best condition for P. versicolor to degrade dieldrin and trifluralin added at 10 ppm. However, for simazine this occurred in the driest water potential (-0.28 MPa) used.

The study was conducted to monitor pesticide residues in groundwater of two agriculturally intensive regions of Alberta, to determine the occurrence of pesticide residues in soil and groundwater of an experimental plot in southern Alberta, and to investigate the influence of land management factors and soil depth on pesticide residues in soil. A total of 440 groundwater samples were collected in three years (2013-2015) and analyzed for the presence of 142 pesticides using Liquid-liquid Extraction (LLE) in combination with Gas Chromatography- Mass Selective Detector (GC-MSD) and Gas Chromatography - Tandem Mass Spectrometry (GC-MS/MS). Ten herbicides, seven insecticides, and six fungicides were detected. Herbicides 2,4-D, MCPA, and clopyralid were the most frequently detected, and the only pesticides consistently detected every year in both regions. Pesticides were detected more frequently in summer and fall compared to spring. 4.5% of the samples were contaminated with more than one pesticides. No pesticides exceeded the Guidelines for Canadian Drinking Water Quality. Similarly, a total of 213 groundwater samples (December 2014-November 2015) and 61 soil samples (in December 2014) in duplicates were analysed from the experimental plots in Lethbridge. Soil samples were collected at various depths (0-75 cm) and analyzed for the presence of 130 pesticides. A linear mixed effect model was fitted to determine the effect of soil depth, cropping systems and manure amendments on pesticide concentration in soil. In groundwater, bentazone, 2,4-D, and MCPA occurred most frequently and pesticide detection frequency varied seasonally with greater detections in July and September compared to other months. 37 different pesticide compounds were detected, and DDT isomers, 2,4-D, difenoconazole, MCPA and trans-heptachlor epoxide accounted for 85% of all detections. p,p’-DDE, 2,4-D, p,p-DDT, difenoconazole and MCPA occurred throughout the soil column and all of these except p,p-DDT were detected in underlying groundwater. Bentazone was found in groundwater throughout the year but not in soil. A greater number and higher concentrations of pesticides were found in soil. However, not all of them leached to groundwater. Soil depth and cropping system were significantly associated with total pesticide and total DDT concentration in the soil. Manure amendments had no affect pesticide concentrations. / May 2017

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The irrigated agriculture of Rio Grande do Sul (RS) it is responsible for about 50% of the Brazilian production of rice, and the success of the production depends, generally, of the application of chemical substances. Many of the cultivated areas are infested with red rice, which cause damages in the production and commercialization of the grains. In this sense, it was developed to cultivate that was adapted to the cultivation of tolerant irrigated rice to the imidazolinones herbicides used for the control of the red rice. The cultivation of irrigated rice generates a great impact to the environment, so much in amount as in the quality of the waters. In this work it was developed and validated a method for determination, in waters and soils, of clomazone, imazapic and imazethapyr herbicides residues. They were analysed for HPLC-DAD, being used mobile phase of acetonitrile:water and stationary phase C18 and for the soil samples it was made the confirmation by LC-MS/MS, with ionization electrospray in the way ESI+ mode. For pre-concentration of the samples SPE was used with cartridges C18. The herbicides were eluated with dichlorometane:methanol, and for extraction in the soils was used solvent and ultrasonic bath. The parameters of validation of the method include analytical curve, linearity, limit of detection (LOD), limit of quantification (LOQ), precision and accuracy (recovery). Whole the analytical curves presented larger values of r2 more than 0.99. The LOQs for the method, considering the stage of pre-concentration of 200 times, were 0.12 μg L-1 for the imazethapyr and imazapic herbicides and 0.25 μg L-1 for the clomazone in samples of water. For the soil samples the values of LOQ were of 2.5 μg kg-1 for imazethapyr and imazapic and 5.0 μg kg-1 for clomazone by HPLC-DAD. The values of LOQ for the soil samples for the system LC-MS/MS was 25.0 ng kg-1. The recoveries were between 80.9 and 106.7%, with RSDs smaller than 9.0% for the samples of water and recoveries between 89.3 and 105.7% with smaller RSDs than 8.7% for soil samples. The method was applied in dissipation studies in the irrigated rice and in the determination of the residual concentration in soil samples, where were applied the herbicides, in the crops of 2004/05, 2005/06 and 2006/07. They were found imazethapyr residues at the most 28 days and of the imazapic 21 days after application and the clomazone until 42 days after application of the products in samples of water. In the soil samples were found imazethapyr residues and imazapic in different collected depths. / A lavoura arrozeira do Rio Grande do Sul (RS) é responsável por cerca de 50% da produção brasileira de arroz, e o sucesso da produção depende, geralmente, da aplicação de substâncias químicas. Muitas áreas cultivadas são infestadas com arroz vermelho que causa prejuízo na produção e na comercialização dos grãos. Neste sentido, foi desenvolvida uma cultivar adaptada ao cultivo de arroz irrigado tolerante à herbicidas imidazolinonas usados para o controle do arroz vermelho. O cultivo de arroz irrigado gera um grande impacto ao meio ambiente, tanto em quantidade como na qualidade das águas. Neste trabalho, foi desenvolvido e validado um método para determinação, em águas e solos, de resíduos dos herbicidas clomazona, imazapique e imazetapir. Foram determinados por HPLC-DAD, utilizando-se fase móvel de acetonitrila:água e fase estacionária C18, para as amostras de solo foi feita a confirmação por LC-MS/MS, com fonte de ionização electrospray no modo ESI+. Para pré-concentração das amostras utilizouse SPE com cartuchos C18. Os herbicidas foram eluídos com diclorometano:metanol, e para extração nos solos foi utilizada extração com solvente e ultra-som. Os parâmetros de validação do método incluem curva analítica e linearidade, limite de detecção (LOD) e de quantificação (LOQ), precisão e exatidão (recuperação). Todas as curvas analíticas apresentaram valores de r2 maiores que 0,99. Os LOQs para o método, considerando a etapa de pré-concentração de 200 vezes, foram de 0,12 μg L-1 para os herbicidas imazetapir e imazapique e 0,25 μg L-1 para o clomazona em amostras de água. Para as amostras de solo os valores de LOQ foram de 2,5 μg kg-1 para imazetapir e imazapique e de 5,0 μg kg-1 para clomazona, por HPLC-DAD. Os valores de LOQ para as amostras de solo para o sistema LC-MS/MS foram de 25,0 ng kg-1. As recuperações ficaram entre 80,9 e 106,7%, com RSDs menores que 9,0% para as amostras de água e recuperações entre 89,3 e 105,7% com RSDs menores que 8,7% para amostras de solo. O método foi aplicado em estudos de dissipação na lavoura de arroz irrigado e na determinação da concentração residual em amostras de solo, onde foram aplicados os herbicidas, nas safras de 2004/05, 2005/06 e 2006/07. Foram encontrados resíduos de imazetapir até no máximo em 28 dias e do imazapique em 21 dias após aplicação e o clomazona até 42 dias após aplicação dos produtos em amostras de água. Nas amostras de solo, foram encontrados resíduos de imazetapir e imazapique em diferentes profundidades coletadas.