Anderson Nascimento do Vasco

Herbicidas no alto Rio Poxim, Sergipe e os riscos de contaminação dos recursos hídricos

Increased agricultural activity in watershed areas has been causing concern over contamination by herbicides in agricultural areas. The problem becomes more important when contamination can affect water for human consumption, as happens with water from the Poxim river, which supplies the city of Aracaju, capital of the State of Sergipe. The aim of this study was to evaluate the risk of contamination by herbicides to both surface and groundwater in the upper sub-basin of the Poxim River, and to detect the presence of the active ingredients Diuron and Ametrine up-river from the sugar-cane plantations. Risk analysis was carried out using criteria from the Environmental Protection Agency (EPA), the GUS index, and the GOSS method. It was observed that several active ingredients are at risk of leaching, demonstrating the importance of monitoring the river to control both the quality of water and the frequency and volume of herbicides used in the region. Based on the results, monitoring was carried out bi-monthly from July 2009 to July 2010 at two sampling points. Water samples were analyzed in the laboratory, where the presence of Diuron and Ametrine was noted. Water quality in the Sub-basin of the Rio Poxim is being influenced by the use of herbicides in the region. There was an increase in herbicide concentration in the surface water during the rainy season, possibly caused by soil runoff.

Environmental indicators of soil in the areas of the headwaters in Piauitinga river basin, Sergipe

Com o objetivo de definir estrategias para recuperacao de areas degradadas nas nascentes da bacia hidrografica do rio Piauitinga em Sergipe; foram utilizados indicadores ambientais: textura, materia orgânica particulada, estabilidade de macro agregados, diâmetro medio de agregados, valor da cor, pH, carbono orgânico, Ca, Mg, Al, Na, K, P, H+Al, N, soma de bases, capacidade de troca cationica, saturacao de bases e saturacao de Al. Os atributos foram analisados em amostras nas profundidades de 0 a 0,1 m e 0,1 a 0,3 m. As nascentes foram previamente divididas em grupos de sitios, considerando sua posicao na paisagem e caracteristicas dos solos locais (BA, EA, EH, ES e SE). Foram determinados os coeficientes de correlacao de Pearson entre os eixos da ordenacao por NMS e entre os diferentes atributos. Considerando o conjunto de variaveis analisadas, o ordenamento dos grupos foi mais efetivo a partir das amostras de 0m a 0,1 m, relativamente as de 0,1 a 0,3 m. O ordenamento realizado com 30 variaveis estudadas permitiu gerar um gradiente ambiental, com a qualidade dos solos decrescendo na seguinte sequencia: baixada, encosta com hidromorfismo, encosta com horizonte A e encosta sem horizonte A. As variaveis fisicas e quimicas estudadas dos solos das nascentes do alto curso do rio Piauitinga, por meio da analise multivariada, permitiram a construcao de um gradiente ambiental, com a qualidade dos solos decrescente na sequencia: baixada, encosta com hidromorfismo, encosta com horizonte A e encosta sem horizonte A. Abstract This study aims at defining strategies for the recovery of degraded areas in water springs of the hydrographic basin of Piauitinga river in Sergipe. Thus, the following environmental indicators were used: texture, particulate organic matter, stability of macro aggregates, aggregates of average diameter, color value, pH, organic carbon, Ca, Mg, Al, Na, K, P, H + Al, N, sum of bases, cation exchange capacity, base saturation, Al saturation. The attributes were analyzed in samples from depths of 0 to 0.1 m and 0.1 to 0.3 m. The water springs were previously divided into sites of groups, considering their position in the landscape and characteristics of local soils (BA, EA, EH, ES and SE). It was determined the Pearson correlation coefficients between the axes of ordination by NMS and between different attributes. Considering the variables analyzed, the arrangement of groups was more effective from the samples 0m to 0.1 m, in comparison to 0.1 to 0.3 m. The ordering conducted with 30 studied variables enabled to generate an environmental gradient, with the quality of soil decreasing in the following sequence: lowland, hydromorphic slope, slope with horizon A and slope without horizon A. The physical and chemical variables analyzed of the water spring soils of the high stream of Piauitinga river, by means of multivariate analysis, enabled the construction of an environmental gradient, with the quality of soil decreasing in the following sequence: lowland, hydromorphic slope, slope with horizon A and slope without horizon A.