Mapeamento do halo de dispersão formado por efluentes industriais lançados na Baía do Guajará no trecho compreendido entre o bairro de Val-de-Cães e o Distrito de Icoaraci

Abstract

The region metropolitan of Belém concentrates a big number of industries in the following between the neighborhood of Val de Cães and the district of Icoaraci. Those industries, among the which, of the catch, brewery and other, liberate efluentes for the bay of the Guajará many times without no handling. The estuary has an intense hydrodynamics and consequently a big capacity of dilution of the pollutants thrown by the industries installed to its margins. However, if the concentration of those infection substances exceed certain limits, the waters of the estuary can lose the capacity of dilution of exhale. In order to be decided to capacity of the bay of the Guajará in scatter the contaminante, thrown by the industries installed to his margins, were carried out three campaigns for superficial water samples collection in a stretch understood between the neighborhoods of Val de Cães and the district of Icoaraci. To first campaign was carried out in the month of May, corresponding to the rainy period, and the other two in the months of August, period of dry spell and November, beginning of the rainy period, all in 2005. The samples were collected to 0, 50, 100, 200 and 400 meters of the margin of the estuary, in front of the company of catch, brewery and slaughterhouse, where were analyzed the parameters pH,electric transmit, color, whirlwind, stuff of suspended particles, oxygen dissolved, oxygen consumed, CO2 free, nitrate, total match, sulphate, alkalined total and the kátions Na, K, Ca and Mg. The values of oxygen dissolved in the stretch studied short saints considered for the region, with values increasing in direction to the interior of the bay, being that the biggest concentrations were obtained in the rainy period. The oxygen consumed, by his time, has inverse behavior, with the biggest values obtained near alongside the bay, where does it influence of the sewers and, consequently, the content of organic matter is bigger. The nitrate obeys to no standard of spatial distribution, however, regarding the seasonal variation, presents bigger values in the month of December. The total match presents sharp difference of quantities between the rainy and dry periods. Being the biggest values recorded in the rainy period. Spatially, the distribution of that increased nutrient in the quota 100m, due to the presence of the tubing of industrial sewers that throw efluentes to 100m of the margin. The sulphate reaches bigger concentrations in the month of November, not having been observed cross and longitudinal standards in his distribution, what suggests that this nutrient does not have relation with the launching of sewers in the waters of the bay. The kátions present his bigger concentrations in the period of dry spell, what suggests minor dilution by the waters. Spatially, the distribution of kátions increased in the sense Val de Cães - Icoaraci due to the biggest one influences of the ocean waters. In general, some parameters as pH,eletric transmission, color, stuff of suspended particles, whirlwind, CO2 free and alkalinide do not suffer significant changes in the values regarding his spatial distribution, already others parameters like the oxygen dissolved and the nutrients present changes to the long one of the 400 meters of the margin of the estuary, mainly due to the influence anthropologic. However, all of the parameters present modifications regarding the seasonal variation, where the biggest values are observed during the period of dry spell, when there is water capacity minor in the bay.