Determinação do grau de trofia no Baixo Tietê, região de Araçatuba, SP, por meio da comparação de dois diferentes indices de estado trófico
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2021-01-29
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Universidade Estadual Paulista (Unesp)
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Este trabalho trata de um estudo realizado no baixo rio Tietê, localizado no Oeste Paulista, inserida na Unidade de Gerenciamento de Recursos Hídricos (UGRHI) 19, município de Araçatuba, com o objetivo de obter o grau de trofia da água por meio do cálculo do índice de estado trófico (IET). Foram previamente estabelecidos dois pontos de coletas, que contemplavam o ponto de captação de água para a Estação de Tratamento de Água Tietê em Araçatuba/SP e um segundo ponto a aproximadamente 1km do ponto de captação da mesma estação, próximo à praia municipal. As amostras foram coletadas na superfície, em meia água e a aproximadamente 1m acima do fundo, nos meses de maio, junho, outubro e novembro de 2020, totalizando quatro coletas. As amostras foram encaminhadas ao laboratório para determinação de clorofila-a, concentração do fósforo total e concentração do ortofosfato; transparência da água foi determinada no local da coleta por meio do disco de Secchi. Após a determinação dos parâmetros foram estabelecidos os índices do estado trófico (IET), utilizando-se os métodos de Carlson modificado por Toledo Jr e de Lamparelli. Os resultados obtidos demonstram que os pontos estudados se encontravam predominantemente em estado eutrófico; em alguns pontos de superfície a classificação trófica foi determinada como mesotrófica. Esta condição infere sobre os riscos de degradação do ambiente, em suas aplicações nos seus usos múltiplos, bem como a saúde ambiental. O estudo permitiu observar que os dois métodos aplicados para determinação do índice de estado trófico obtiveram resultados muito semelhantes, não sendo possível avaliar um método como mais eficiente do que o outro. Sendo assim, a utilização do IET é uma forma interessante de avaliar a qualidade de corpos hídricos, facilitando a interpretação e divulgação dos resultados obtidos e, quando aplicado a corpos aquáticos de uma mesma região, permite a rápida avaliação comparativa do estado trófico dos mesmos.
This work deals with a study carried out in the lower Tietê River, located in the West of São Paulo, inserted in the Water Resources Management Unit (UGRHI) 19, a municipality of Araçatuba, with the objective of obtaining the degree of water treble by calculating the trophic state index (TeE). Two collection points were previously established, which included the water collection point for the Tietê Water Treatment Station in Araçatuba/SP and a second point approximately 1 km from the capture point of the same station, near the municipal beach. The samples were collected on the surface, in half water and approximately 1 m above the bottom, in the months of May, June, October, and November 2020, totaling four collections. The samples were sent to the laboratory for chlorophyll-a determination, total phosphorus concentration, and orthophosphate concentration; transparency of water was determined at the collection site using the Secchi disc. After the determination of the parameters, the trophic state indexes (TSI) were established, using the Carlson methods modified by Toledo Jr and Lamparelli. The results obtained show that the studied points were predominantly in a eutrophic state; at some surface points, the trophic classification was determined as mesotrophic. This condition infers about the risks of environmental degradation, in its applications in its multiple uses, as well as environmental health. The study allowed us to observe that the two methods applied to determine the trophic state index obtained very similar results, and it was not possible to evaluate one method as more efficient than the other. Thus, the use of The EIT is an interesting way to evaluate the quality of water bodies, facilitating the interpretation and dissemination of the results obtained and, when applied to aquatic bodies of the same region, allows the rapid comparative evaluation of their trophic state.
This work deals with a study carried out in the lower Tietê River, located in the West of São Paulo, inserted in the Water Resources Management Unit (UGRHI) 19, a municipality of Araçatuba, with the objective of obtaining the degree of water treble by calculating the trophic state index (TeE). Two collection points were previously established, which included the water collection point for the Tietê Water Treatment Station in Araçatuba/SP and a second point approximately 1 km from the capture point of the same station, near the municipal beach. The samples were collected on the surface, in half water and approximately 1 m above the bottom, in the months of May, June, October, and November 2020, totaling four collections. The samples were sent to the laboratory for chlorophyll-a determination, total phosphorus concentration, and orthophosphate concentration; transparency of water was determined at the collection site using the Secchi disc. After the determination of the parameters, the trophic state indexes (TSI) were established, using the Carlson methods modified by Toledo Jr and Lamparelli. The results obtained show that the studied points were predominantly in a eutrophic state; at some surface points, the trophic classification was determined as mesotrophic. This condition infers about the risks of environmental degradation, in its applications in its multiple uses, as well as environmental health. The study allowed us to observe that the two methods applied to determine the trophic state index obtained very similar results, and it was not possible to evaluate one method as more efficient than the other. Thus, the use of The EIT is an interesting way to evaluate the quality of water bodies, facilitating the interpretation and dissemination of the results obtained and, when applied to aquatic bodies of the same region, allows the rapid comparative evaluation of their trophic state.
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Eutrofização, Qualidade Hídrica, Fósforo, Nitrogênio, Clorofila, Eutrophication, Water quality, Phosphorus, Nitrogen, Chlorophyll