Trophic level of the reservoir Jacarecica I – Sergipe – Brasil

Abstract

The objective of this study was to evaluate the trophic state of water and identify the limiting nutrient reservoir Jacarecica I (Sergipe, Brazil), using the trophic state index (EIT) by Carlson. The physical, chemical and biological agents used were pH, transparency, electrical conductivity, ammonia, nitrite, nitrate, total nitrogen, total phosphorus, dissolved oxygen and chlorophyll-a. For these parameters, it is noteworthy that the concentrations of all nutrients were higher during the rainy season than during the dry season, most logically by deposition of organic matter to just over irrigated. The values of total phosphorus, dissolved oxygen and chlorophyll a exceeded the limits established in Resolution No. 375/05 of CONAMA for Class 1 and Class 2 water. Noted also that the limiting nutrient was nitrogen reservoir during the dry and phosphorus during the rainy season. Furthermore, based on the results of the EIT, the classification of the reservoir ranged from eutrophic to oligotrophic depending on season and sampling site, resulting in reduction of the trophic state towards the river to the dam.