[Show abstract][Hide abstract] ABSTRACT: O objetivo deste estudo foi avaliar o efeito das concentrações dos herbicidas
imazetapir, imazapique e bispiribaque-sódico na comunidade zooplanctônica (Cladocera,
Copepoda e Rotifera) na lavoura de arroz. A diminuição da dissipação de meia-vida
(DT50) desses herbicidas em estudo na água foi: imazetapir, imazapique
e bispiribaque-sódico, com uma média de 3,75, 3,73 e 1,91 dias, respectivamente. A
mistura de imazetapir com imazapic provocou alteração no zooplâncton analisado, com
incremento nas densidades dos grupos Cladocera e Copepoda adultos, enquanto que
bispiribaque-sódico causou redução de densidade no grupo Copepoda, tanto adulto
quanto náuplio, nas amostragens iniciais. Dentre os grupos, Rotifera foi pouco
sensível aos herbicidas.
[Show abstract][Hide abstract] ABSTRACT: The aim of this research was to evaluate possible toxic effects of commercial formulation containing fipronil on Cyprinus carpio tissues under rice field conditions. Antioxidant profile (SOD, catalase, glutathione S-transferase), oxidative stress parameters (thiobarbituric acid-reactive substances, protein carbonyl), and growth were investigated in carp exposed to fipronil under rice field conditions for 7, 30, and 90 days. Waterborne insecticide concentrations were measured and the detectable concentration of fipronil was observed up to 45 day after application. Common carp survival and growth was not affected by fipronil. Liver superoxide dismutase activity was enhanced while liver catalase activity was inhibited at 7, 30, and 90 days. Alterations were not observed in the glutathione S-transferase activity in any experimental periods. Protein carbonyl increased only after 30 and 90 days of exposure. The thiobarbituric acid-reactive substances levels were enhanced in all analyzed tissues (liver, muscle, and brain) and periods of exposure. This study demonstrates that fipronil insecticides cause alterations in the biochemical parameters in different tissues of carp without affecting the growth or the survival of the fish.
[Show abstract][Hide abstract] ABSTRACT: Cyprinus carpio was exposed to imazethapyr and imazapic at laboratory and at field conditions. The laboratory experiment was carried out for 7 days and at rice field for 7, 30 and 90 days. Oxidative stress parameters and antioxidant profile were studied as well as metabolic parameters. After 7 days, brain AChE activity increases in laboratory and field, but in muscle, reduction was observed only in laboratory. At the same period, brain and muscle TBARS and liver CAT increase in the laboratory. Metabolic parameters showed changes in both conditions and exposure periods. After 30 days in rice field, brain AChE activity decreases and in muscle it was enhanced. After 90 days in field, only muscle AChE activity was reduced. The disorders in oxidative stress parameters and metabolism remained, indicating mainly a protein catabolism. This study pointed out short- and long-term effects of rice herbicides at environmentally relevant concentrations on toxicological parameters in tissues of C. carpio.
[Show abstract][Hide abstract] ABSTRACT: The effects of commercial formulation containing quinclorac and metsulfuron-methyl herbicides on acetylcholinesterase (AChE), antioxidant profile and metabolic parameters in teleost fish (Leporinus obtusidens) were studied. The fish were exposed during 90 days to commercial formulation containing quinclorac (204 μg L(-1)) and metsulfuron-methyl (5.8 μg L(-1)) herbicides in rice field irrigated condition. AChE activity in the brain and muscle decreased after exposure to both commercial formulations. The same response was observed for the TBARS levels in brain, liver and muscle. Liver catalase activity reduced after exposure to commercial formulation containing quinclorac and metsulfuron-methyl herbicides. Metabolic parameters in the liver and white muscle (glycogen, lactate, protein and glucose) were determined. These parameters showed different changes after exposure to both commercial formulations. This study pointed out long-term effects of exposure to commercial formulations containing herbicides used in rice on metabolic and enzymatic parameters in tissues of L. obtusidens.
[Show abstract][Hide abstract] ABSTRACT: Aiming to estimate the number of samples, and the diameter of soil sampler ideal for red rice infestation level, a irrigated rice field survey has been conducted in Santa Maria, Rio Grande do Sul (RS), Brazil, The experiment was conducted in three areas with 400m2 (20x20m) with different red rice infestation levels considering low, medium and high infestation levels with 71, 282 and 498 red rice seeds per m2, respectively, sample with 5, 10 and 15cm core diameter. The results showed that with larger core diameter the samples coefficient variation among samples was smaller. The core of 10 cm is more functional, been necessary 280, 55 and 31 (D=20%), 33, 9 and 6 (D=60%) and 13, 4 and 3 (D=100%) soil samples for the infestation levels 71, 282 and 498 red rice seeds per m2 respectively. The number of soil samples necessary to estimate the red rice seed bank is variable with the infestation level and the desirable precision.
[Show abstract][Hide abstract] ABSTRACT: Common carp (Cyprinus carpio) and bighead carp (Aristichthys nobilis) were exposed to azimsulfuron and metsulfuron-methyl (50, 100 and 200 mg L-1). These herbicides are used in rice crop in Southern Brazil. Fishes survived to all tested concentrations of both herbicides and showed normal feeding and swimming behavior. Azimsulfuron inhibits significantly acetylcholinesterase (AChE) in brain and muscle of both species, and metsulfuron-methyl increase AChE activity in brain and inhibits in muscle. The present study showed that azimsulfuron and metsulfuron-methyl did not affect C. carpio and A. nobilis behaviors (feeding and swimming), but inhibited AChE activity in brain and muscle tissues of these species.
[Show abstract][Hide abstract] ABSTRACT: Com o objetivo de determinar o diâmetro ideal do trado e o número de amostras necessárias para quantificar o banco de sementes de arroz-vermelho, foram realizados levantamentos em lavouras de arroz irrigado, no Município de Santa Maria, Rio Grande do Sul (RS), Brasil. O experimento foi conduzido em três áreas de 400m2 (20x20m), com diferentes níveis de infestação, sendo considerado nível baixo, médio e alto, respectivamente, 71, 282 e 498 sementes de arroz-vermelho por m2, coletadas com trados de 5, 10 e 15cm de diâmetro. Os resultados mostraram que, quanto maior o diâmetro do trado, menor foi o CV entre as amostras. O trado com 10cm de diâmetro foi mais funcional e necessitou de 280, 55 e 31 (D=20%); 33, nove e seis (D=60%); e 13, quatro e três (D=100%) amostras de solo, respectivamente, para as infestações de 71, 282 e 498 sementes de arroz-vermelho por m2. O número de amostras de solo necessário para melhor estimar populações de sementes de arroz-vermelho é variável com o número médio de sementes no solo e com a precisão desejada.
[Show abstract][Hide abstract] ABSTRACT: Water is an important natural resource for preserving the life in the planet. In this survey, it was evaluated water quality in the Vacacaí and Vacacaí-Mirim basins in Rio Grande do Sul State, Brazil. The water samples were evaluated for N-nitrate (N-NO3), phosphorus (P), potassium (K) and sodium (Na), pH and electric conductivity (EC). The results were compared to the values suggested by the resolutions of the State Environmental Agency (Secretaria da Saúde e Meio Ambiente), the Brazilian Agencies (CONAMA e Ministério da Saúde) and the United States Environmental Protection Agency (EPA). The water pH varied between 5.71 and 7.5 and de EC between 33.33 and 118.88µS cm-1. For N-nitrate 100% samples were in the settled limits by environmental legislation. The P levels were between 0.00 to 0.18mg L-1. The N-ammonia levels varied between 0.02 and 0.39mg L-1, the K levels remained between 2.05 and 3.66mg L-1 and the Na levels between 1.84 and 16.8mg L-1.
[Show abstract][Hide abstract] ABSTRACT: Pesticides, such as herbicides can affect the metabolic and toxicological parameters on fish. For this reason, an experiment was carried out with the objective of to evaluate the effects of commercial formulations of clomazone and propanil herbicides on acetylcholinesterase (AChE), thiobarbituric acid-reactive substances (TBARS), catalase (CAT) and metabolic parameters in teleost fish (Leporinus obtusidens). Fish were exposed during 90 days to field measured concentration of the herbicides clomazone and propanil (376 and 1644 μg/L, respectively) on rice paddy water. Specific AChE activity in the brain and muscle decreased and TBARS levels decreased in brain, muscle and liver tissues. Liver catalase decreased after exposure to both herbicides. Metabolic parameters in the liver and white muscle showed different changes after exposure to both herbicides. In summary, the results showed that clomazone and propanil affects toxicological and metabolic parameters of piavas. These results suggest that environmentally relevant herbicides concentrations are toxic to Leporinus obtusidens.
[Show abstract][Hide abstract] ABSTRACT: This study determined the effects of metsulfuron-methyl, azimsulfuron and carbofuran in communities: Cladocers, Copepods and Rotifers that are present in irrigated rice farming with the rice-fish system. The field experiment was conducted in the 2004/05 growing season with eight treatments. The fish species were: Cyprinus carpio, Ctenopharyngodon idella and Aristichthys nobilis, introduced seven days after treatments were applied. Water samples were collected 17 days before and 1st, 3rd, 10th, 18th, 31th, 51th, and 75th days after the agrochemicals were applied for identification and evaluation of the zooplankton. The results indicated that the herbicides did not affect the zooplankton community studied and carbofuran insecticide application provoked negative effects in Cladocers. Copepods and Rotifers were slightly affected by carbofuran
[Show abstract][Hide abstract] ABSTRACT: Em lavoura de arroz irrigado, é utilizada uma grande quantidade de agroquímicos que, dependendo da sua persistência a campo e toxicidade, podem contaminar corpos dágua e afetar organismos vivos. Com o objetivo de determinar o efeito de concentrações de campo dos herbicidas Clomazone, Quinclorac, Metsulfuron-methyl e Propanil na comunidade zooplanctônica (Cladocera, Copepoda e Rotifera), conduziu-se um experimento em viveiros de aqüicultura, de março a maio de 2005, na estação do outono. Nos dias 1°, 2°, 3°, 7°, 10°, 18°, 31° e 51° após a aplicação dos herbicidas, foram coletadas amostras de água para se determinarem parâmetros físico-químicos da água, concentração dos herbicidas e comunidade zooplanctônica. Os parâmetros médios da qualidade da água foram: oxigênio dissolvido (3,5mg L-1), temperatura (20,1°C), pH (6,0), dureza total (18mg L-1 de CaCO3) e alcalinidade total (9mg L-1 de CaCO3). A ordem decrescente de persistência dos herbicidas na água foi Clomazone = Quinclorac > Propanil > Metsulfuron-methyl, com média de 31, 31, 10 e 7 dias, respectivamente. Os resultados indicaram que os herbicidas provocaram poucas alterações na densidade de organismos dos grupos Rotifera e Copepoda (Adulto e Nauplio). A densidade do grupo Cladocera permaneceu baixa para todo o período experimental.
[Show abstract][Hide abstract] ABSTRACT: In the rice paddy field it is used a large amount of agrochemical that, depending on their field persistence and toxicity, can contaminate water bodies and may affect living organism. With the objective of determining the effect of field concentrations of Clomazone, Quinclorac, Metsulfuron-methyl and Propanil herbicides on zooplankton community (Cladocers, Copepods and Rotifers), it was carried an experiment in aquaculture ponds, during March to May 2005, in autumn season. In the 1st, 2nd, 3rd, 7th, 10th, 18th, 31th and 51th days after the herbicides application, water samples were collected to evaluate the physical chemical water parameters, herbicides concentration and zooplankton community. The water physical chemical parameters means were: dissolved oxygen (3.5mg L-1), temperature (20.1°C), pH (6.0), total hardness (18mg L-1 CaCO3) and total alkalinity (9mg L-1 CaCO3). The decreasing of herbicides persistence in water was: Clomazone = Quinclorac > Propanil > Metsulfuron-methyl with average of 31, 31, 10 and 7 days, respectively. The results indicated that the herbicides provoke little alteration in density of Rotifers and, Copepods (Adults and Nauplii). The Cladocers group density remained low for the whole experiment period.
[Show abstract][Hide abstract] ABSTRACT: Este trabalho foi conduzido com o objetivo de avaliar a sobrevivência de alevinos de carpas expostas ao carbofurano, metsulfurom-metílico e azinsulfurom em rizipiscicultura, bem como a produção de arroz irrigado e peixes. Foram utilizados alevinos de carpas húngara, capim e cabeça grande, expostos aos agroquímicos em sistema pré-germinado de produção de arroz com manejo adequado de lâmina de água contínua, durante os anos agrícolas de 2003/04 e 2004/05. Adotou-se delineamento experimental de blocos ao acaso com oito tratamentos e quatro repetições, associando carpas sob a presença ou ausência dos agroquímicos. Os alevinos de carpas foram colocados na área sete dias após a aplicação dos produtos, sendo verificado que os agroquímicos não afetaram sua sobrevivência. Devido a utilização de lâmina contínua de água no sistema, a produção de grãos de arroz também não foi afetada pela utilização de agroquímicos.