QUALIDADE DA ÁGUA DE RESERVATÓRIOS NAS DISTINTAS ZONAS CLIMÁTICAS DA PARAÍBA (water quality of reservoirs in Paraíba’s diverse climatic zones)
Abstract
Este trabalho teve como objetivo principal analisar a qualidade da água de grandes reservatórios do estado da Paraíba destinados ao abastecimento público. Foram escolhidos nove reservatórios distribuídos nas zonas úmida (As’), semi-árida (Bsh) e sub-úmida (Aw’) do estado. A metodologia consistiu em levantamento bibliográfico, cartografia digital, trabalhos de campo, análises laboratoriais e cálculo do Índice de Qualidade da água (IQA). Constatou-se que, durante 2007, os nove reservatórios apresentaram água de boa e ótima qualidade. Entre as diferentes regiões climáticas do estado, os resultados dos IQAs foram melhores nos reservatórios do Cariri (Bsh), seguidos pelos do Sertão (Aw’), e os mais baixos foram encontrados na Zona da Mata (As’). Sete dos nove reservatórios apresentaram melhor qualidade da água durante a estação seca. Apesar dos resultados de qualidade terem sido satisfatórios, alguns parâmetros estavam em desacordo com os limites estabelecidos pela resolução CONAMA (357/2005) para águas doces da classe 2. O fósforo total foi o único parâmetro que extrapolou o limite máximo permitido em todos os reservatórios. O maior número de parâmetros em desacordo com o limite permitido ocorreu nos reservatórios da Zona da Mata onde se verificou predomínio de áreas 100% antropizadas no entorno dos reservatórios.
Palavras-chave: Paraíba, qualidade da água, reservatórios
ABSTRACT
This study had as main aims to analyze water quality in large water reservoirs in Paraiba destined to public use. Nine reservoirs evenly distributed in the three climatic regions of the state were chosen: humid region (As’), semi-arid region (Bsh) and sub-humid region (Aw’). The methodology consisted in bibliographic research, digital cartography, field work, laboratory analyses and determination of the Water Quality Index (WQI). During 2007 the water quality of the nine reservoirs was between good and excellent. The WQI results were better in reservoirs in the Cariri region (Bsh), followed by the ones in the Sertão region (Aw), and the lowest were found in reservoirs in the rainforest region (As). Seven of nine reservoirs presented small increases of water quality in the dry season. Even though the water quality results were satisfactory, some parameters were out of the range allowed by the CONAMA resolution (357/2005) for class 2 freshwater reservoirs. Total phosphorus was the only parameter that extrapolated the allowed limit in all reservoirs. The highest number of parameters out of the allowed range occurred in the rainforest region’s reservoirs, where it was observed 100% antropism in the reservoirs’ surrounding areas.
Key-words: Paraíba, water quality, reservoirs
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