João Batista Rossetto Pellegrini

Investigation of the occurrence of pesticide residues in rural wells and surface water following application to tobacco

In this work the exposure of wells and surface water to pesticides, commonly used for tobacco cropping, was assessed. Water consumption wells and surface water flows were sampled at different times. After a preconcentration step with solid phase extraction (SPE), the selected pesticides were determined by gas chromatography with electron capture detection (GC-ECD) or high performance liquid chromatography with diode array detection (HPLC-DAD). No pesticides were detected in the well water samples and surface water flow in the winter season. However, in the spring and summer higher concentrations of chlorpyrifos and imidacloprid were found in the water source samples. Atrazine, simazine and clomazone were also found. The occurrence of pesticides in collected water samples was related with the application to tobacco.

Contaminação de águas superficiais por agrotóxicos em função do uso do solo numa microbacia hidrográfica de Agudo, RS

This work was accomplished with the intention of quantifying the presence of pesticide molecules in surface waters of three landscape units (LU) with different usage configurations in the Agudo watershed of the State of Rio Grande do Sul, Brazil. Two semiautomatic water collectors were installed at the stream of each LU, from which samples were collected during rain over three stages of the tobacco growing season: seedling transplant, tobacco plants with 6-10 expanded leaves, and at harvest. Imidacloprid, atrazine, simazine, and clomazone compounds were quantified by High Performance Liquid Chromatography with Ultraviolet Detector (HPLC-UV). Chlorpyrifos, flumetralin and iprodione were analyzed by Gas Chromatography with Electron Capture Detector (GC-ECD), but these compounds were not detected in the samples. The sampling points where the LU was configured with both the presence of tobacco crops and reduced gallery forest, showed at least one pesticide compound in a sampling time. No pesticide was detected in the LU, which is completely covered with permanent vegetation or with gallery forest protecting the water courses.

Influência da adubação fosfatada e da introdução de espécies forrageiras de inverno na oferta de forragem de pastagem natural

The beef cattle production in Rio Grande do Sul, Brazil, is based on natural pasture grazing, which are of low productivity and seasonal growth. The present work was done to test the effects of Italian ryegrass and arrowleaf clover introduction in natural pasture under different phosphorus fertilizer, soluble and natural, associated or not to the lime, on forage improvement from natural pasture. The study was conducted at Universidade Federal de Santa Maria on a Paleudalf. The treatments were: foscal (simple superphosphate + lime); triple superphosphate + lime; triple superphosphate; rock phosphate of Gafsa; without phosphorus fertilizer and without lime, and natural pasture. Except for the last treatment, the others received potassium and nitrogen fertilizers and introduction of Lolium multiflorum and Trifolium vesiculosum. The autors used 3.2 Mg ha of lime (elevation of the pH-H 2 O to 5.5), 180 kg ha-1 of P 2 O 5 , 130 kg ha-1 of K 2 O and 70 kg ha-1 of N. The productivity of dry matter was evaluated for the following periods: winter, spring, spring-summer and summer-autumn. The phosphorus fertilization increased the productivity of dry matter of the pasture and the soluble phosphates provided greater productions than the rock phosphate. The lime did not increase productivity of Lolium multiflorum and natural pasture, but Trifolium vesiculosum responded to this input.

Qualidade da água numa microbacia hidrográfica de cabeceira situada em região produtora de fumo

Sem respeitar sua capacidade de suporte aliado a utilizacao macica de agroquimicos, o uso agricola do solo vem comprometendo a qualidade da agua superficial. Neste trabalho, teve-se por objetivo monitorar a qualidade da agua do dreno principal de uma microbacia hidrografica (MBH) de cabeceira, situada em area predominantemente produtora de fumo e que utiliza intensamente agroquimicos e manejo convencional. A MBH esta localizada no distrito de Nova Boemia, em Agudo, RS. Coletaram-se amostras para analise em quatro pontos representativos do arroio, nos primeiros oito meses de 2002 e se analisaram, nas amostras de agua, parâmetros microbiologicos, fisicos e quimicos; em um dos pontos avaliou-se a vazao e o transporte de sedimentos durante um evento chuvoso. As maiores concentracoes de poluentes ocorreram nas aguas coletadas nos pontos de maior influencia de lavouras e estabelecimentos rurais. Os meses mais chuvosos coincidiram com as maiores contaminacoes microbiologicas, principalmente por coliformes fecais, enquanto os resultados mostraram que a agua do arroio apresentou concentracao de fosforo muito acima do padrao da classe 3 do CONAMA (1986).

Adsorção de fósforo em sedimentos e sua relação com a ação antrópica

The evaluation of the amount of total and soluble P in surface waters is insufficient to diagnose their pollution potential. This study aimed to evaluate the P fractions and soil properties related to P release from eroded sediments of landscape units with different pressure levels of anthropogenic activity. Water + sediments were sampled in two landscape units of a sub-watershed of the small watershed Arroio Lino, in Agudo, RS, Brazil. The following properties were evaluated: pH, sediment concentration, total organic C, sand, silt and clay fractions, iron extracted by DCB (Fed) and by oxalate (Feox), soluble P (Ps), total P (Pt), bioavailable particulate P (Ppb), potentially bioavailable particulate P (Pppb) and amount of phosphate desorbed with distilled water (Q0). It was possible to estimate the maximum capacity of phosphate adsorption (Pmax), the equilibrium concentration of phosphate (CEP) and the constant (k) related with the phosphate bond energy in the sediment. In comparison with areas with less anthropogenic activity, the sediments eroded from areas with high anthropogenic activity contained: (a) higher Pt and Pppb concentration and lower Ppb quantity; (b) higher Pmax and k values and (c) lower Q0 and CEP quantities. These results indicate the higher pollution potential of eroded sediments from areas with high anthropogenic activity, especially in stagnant water.

Effect of phosphorus fertilizer application and introduction of winter forage species on forage availability in natural pastures.

The beef cattle production in Rio Grande do Sul, Brazil, is based on natural pasture grazing, which are of low productivity and seasonal growth. The present work was done to test the effects of Italian ryegrass and arrowleaf clover introduction in natural pasture under different phosphorus fertilizer, soluble and natural, associated or not to the lime, on forage improvement from natural pasture. The study was conducted at Universidade Federal de Santa Maria on a Paleudalf. The treatments were: foscal (simple superphosphate + lime); triple superphosphate + lime; triple superphosphate; rock phosphate of Gafsa; without phosphorus fertilizer and without lime, and natural pasture. Except for the last treatment, the others received potassium and nitrogen fertilizers and introduction of Lolium multiflorum and Trifolium vesiculosum. The autors used 3.2 Mg ha of lime (elevation of the pH-H 2 O to 5.5), 180 kg ha-1 of P 2 O 5 , 130 kg ha-1 of K 2 O and 70 kg ha-1 of N. The productivity of dry matter was evaluated for the following periods: winter, spring, spring-summer and summer-autumn. The phosphorus fertilization increased the productivity of dry matter of the pasture and the soluble phosphates provided greater productions than the rock phosphate. The lime did not increase productivity of Lolium multiflorum and natural pasture, but Trifolium vesiculosum responded to this input.