Lúcia de Fátima Pereira Araújo

Seleção dos indicadores da qualidade das águas superficiais pelo emprego da análise multivariada

Multivariate statistical technique, factor analysis/principal component analysis (FA/PCA), was applied to identify the human activity effects and natural processes on surface water quality in Low Acarau basin, Ceara, Brazil. Water samples were collected in four different campaigns from Feb/2003 to Mar/2004, at seven sampling stations sited in low Acarau watershed. Twenty-five physical, chemical and bacteriological parameters were examined in this study. The FA/PCA allowed the identification of the total variance. The best model was adjusted with four components, explaining 82.1% of the data variance. The first factor was mainly associated with suspended solids defining the erosion process and runoff; that is, a suspended solids component. The second factor was mainly associated with sewage, agricultural runoff and others non-pontual pollution; the third one was defined as an organic component and represents the anthropogenic activites; while the fourth was mainly correlated with soluble salt, expressing the weathering and leaching. Besides, the factorial analysis did not result in data reduction, since 18 of the 25 parameters have been kept to explain 82% of the data variance.

Impactos ambientais do lançamento de efluentes da carcinicultura em águas interiores

The Baixo Jaguaribe waterbasin has faced the installation of a growing number of shrimp farms along the Jaguaribe River, where there is no saline water interference. This work aims to show the chemical, physical-chemical and bacteriological characteristics of the inland shrimp farms continuous and harvest effluents, located in the Baixo Jaguaribe region, Ceara State, to discuss the possible impacts of these effluents in the water bodies and to suggest mitigating measures. It was analyzed water samples from the Jaguaribe river and the effluents of 2 tanks belonging to 2 different shrimp farms, during 1 production cycle. The parameters analyzed were: pH, turbidity, nitrate, total ammonia, electric conductivity, BOD5, total phosphorus, soluble phosphorus, total alkalinity, total solids, total dissolved solids, total suspended solids, coliform organisms and chlorophylla. The harvest effluents, its was also analyzed DO and the fraction of sedimented solids. The results showed that although the continuous effluents complied with the legislation standards, in the harvest the values obtained from pH, total ammonia , suspended and settleable solids were higher than those allowed by the legislation. The total load resulting from the great volume drained by the shrimp farms contributes to a progressive deterioration of the water bodies quality in the region.

Fatores determinantes da qualidade das águas superficiais na bacia do Alto Acaraú, Ceará, Brasil

Factor analysis/Principal Component Analysis (FA/PCA) were applied to the data set on water quality in upper Acarau River basin (Brazil) to study the effects caused by human activities on water. Variables were measured at six key sampling sites (villages and agricultural areas) in four campaigns from February/2003 to March/2004. The samples were analyzed for pH, temperature, color, electrical conductivity, turbidity, nitrate, ammonia, sodium, chloride, potassium, sulfate, total hardness, calcium, magnesium, total alkalinity, alkalinity bicarbonate, total suspended solids, dissolved oxygen (DO), 5-days biochemical oxygen demand (BOD5), total phosphate, orthophosphate, chlorophyll-a, and feacal coliform. Multivariate statistical techniques, (FA/PCA), allowed the identification of variables that explain the major percent of total variance. Three components were identified as responsible for the data structure, explaining 88% of the total variance of the data set. Model showed that the first factor (39.81% of variance) assigned as mineralization factor. The second one (29.22% of variance) represented as nutrients group. The third factor (19.16% variance) assigned as a combination of agricultural area runoff and weathering. Varimax rotation showed that the mainly water quality parameters were related to mineralization (natural process) and non-point pollution (anthropogenic activities).

Impactos ambientais da carcinicultura de águas interiores

This work aims to identify the main environmental aspects and impacts of the inland shrimp farming, through the analysis of the process stages and different cultivation techniques in farms located in the Baixo Jaguaribe region, Ceara State, Brazil. This evaluation was done applying questionnaires along with all farm owners or managers and making physical-chemical analysis of the effluents and the tanks soil in three selected farms. The main environmental impacts identified are related to the occupation of preservation areas by the shrimp tanks, greater conflicts between water users, contamination of the water resources that are also the main source of drinking water to the municipalities and the increase of diseases among rural workers by the inadequate manipulation of chemical products during production. These impacts can be reduced to match with the region environmental capacity, when the legislation is respected and the good practices are adopted. Besides, it is also recomended to carry out research studies that access the watershed environmental capacity to sustain shrimp farming growth, in order to orient environmental and water use licensing.