Contribuição da cidade de Botucatu - SP com nutrientes (fósforo e nitrogênio) na eutrofização da represa de Barra Bonita
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Data
1997-01-01
Autores
VALENTE, José Pedro Serra [UNESP]
PADILHA, Pedro Magalhães [UNESP]
SILVA, Assunta Maria Marques da [UNESP]
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Editora Unesp
Resumo
As concentrações de nutrientes (fósforo e nitrogênio) na nascente, cidade e foz do ribeirão Lavapés/ Botucatu-SP foram avaliadas e comparadas com as do rio Capivara. O rio Capivara como o ribeirão Lavapés, possui nascente no alto da cuesta e desemboca suas águas na represa de Barra Bonita/ rio Tietê (<a HREF=#fig1>Figura 1</a>). O rio Capivara possui uma das nascentes próxima a uma do ribeirão Lavapés e, ambos possuem a foz próxima uma da outra na represa de Barra Bonita. O uso e tipo de solo nas margens de ambos cursos d´águas são bastante parecidos, o que implica em uma poluição rural semelhante, assim a grande diferença que afeta a qualidade da água, entre os dois cursos d´águas é a poluição urbana, na cidade de Botucatu (ribeirão Lavapés). Deste modo procurou-se avaliar a contribuição de nutrientes (fósforo e nitrogênio) do ribeirão Lavapés e rio Capivara na represa de Barra Bonita , e estimar a carga retida no lodo do ribeirão Lavapés e a despejada na represa em função dos lançamentos de esgotos sanitários no mesmo, na cidade de Botucatu. O trabalho foi realizado em um período de seca, sem alagamentos, o que permitiu medir as vazões próximas da foz e avaliar a carga diária, no período, de nutrientes lançados na represa. Foram avaliados também, oxigênio dissolvido, demanda química do oxigênio e condutividade Elétrica. Embora os resultados sejam estimativos e variáveis no tempo, podemos concluir que a poluição na cidade de Botucatu por esgoto sanitário além de inviabilizar o uso da água no seu percurso, e causar outros prejuízos, contribui para agravar a eutrofização na represa de Barra Bonita.
It was compared the level content of nutrients (phosphorus and nitrogen) at the Lavapés brook with level content at source an cross-tow (domestic sewage discharge) and also with the level/ content at source and mouth the Capivari river. The head-waters of the Capivari river, as well as those of the Lavapés brook, are on the highlands (at the top the sierra/ mountain-range) and its waters flow into the Barra Bonita dan on the Tietê river (<a HREF=#fig1>Figure 1</a>). One of its sources is near a Lavapés source and their mouths are close to each other at the Barra Bonita dam. Along the banks of both streams the use of land and the types of soil are alike, which implies in a similar rural pollution; so, what makes the difference in water quality between them is the urban pollution affecting the Lavapés brook in Botucatu. Therefore it was evaluated the contribution of nutrients (phosphorus and nitrogen) to the Barra Bonita Dam of the Capivari river and the Lavapés brook. Taking into account the domestic sewage carried into the Lavapés brrok in Botucatu, it was estimated the nutrient load of its silt (kept in its silt) and the one discharged into the Barra Bonita dam. The study- was conducted during drought, without overflows, which made it possible to measure the near-mouth-flow and to evaluate the nutrient load daily discharged into the dam. It was also evaluated the dissolved oxygen, the chemical oxygen demand and the electrical conductivity. Although the results are estimated and variabel in time we can conclude that pollution of the Lavapés brook waters with domestic sewage in Botucatu, besides making the use of its waters not viable and causing other (environmental) damage (financial losses), contributes to aggravating the eutrophication at the Barra Bonita dam.
It was compared the level content of nutrients (phosphorus and nitrogen) at the Lavapés brook with level content at source an cross-tow (domestic sewage discharge) and also with the level/ content at source and mouth the Capivari river. The head-waters of the Capivari river, as well as those of the Lavapés brook, are on the highlands (at the top the sierra/ mountain-range) and its waters flow into the Barra Bonita dan on the Tietê river (<a HREF=#fig1>Figure 1</a>). One of its sources is near a Lavapés source and their mouths are close to each other at the Barra Bonita dam. Along the banks of both streams the use of land and the types of soil are alike, which implies in a similar rural pollution; so, what makes the difference in water quality between them is the urban pollution affecting the Lavapés brook in Botucatu. Therefore it was evaluated the contribution of nutrients (phosphorus and nitrogen) to the Barra Bonita Dam of the Capivari river and the Lavapés brook. Taking into account the domestic sewage carried into the Lavapés brrok in Botucatu, it was estimated the nutrient load of its silt (kept in its silt) and the one discharged into the Barra Bonita dam. The study- was conducted during drought, without overflows, which made it possible to measure the near-mouth-flow and to evaluate the nutrient load daily discharged into the dam. It was also evaluated the dissolved oxygen, the chemical oxygen demand and the electrical conductivity. Although the results are estimated and variabel in time we can conclude that pollution of the Lavapés brook waters with domestic sewage in Botucatu, besides making the use of its waters not viable and causing other (environmental) damage (financial losses), contributes to aggravating the eutrophication at the Barra Bonita dam.
Descrição
Palavras-chave
Fósforo, nitrogênio, eutrofização, ribeirão Lavapés, represa de Barra Bonita, carga de nutriente, Phosphorus, nitrogen, eutrophication, Lavapés Brook, Barra Bonita nutrient load
Como citar
Eclética Química. Fundação Editora da Universidade Estadual Paulista Júlio de Mesquita Filho - UNESP, v. 22, p. 31-48, 1997.