Níveis residuais de BHC nos principais rios e lagos da regiao cacaueira do Sul da Bahia, Brasil
By means of gas chromatography the residual levels of BHC (HCH) in six of the main rivers and in two lakes of the Cacao Region of Southern Bahia were determined. The water samples were collected at the end of and three months after the end of the period of insecticide application in the region. Each river was sampled at or before the beginning, at the middle and after the end of its course through the cacao region. For each river included in this study BHC residues were detected in at least one of the three sampling places; the levels varied from not detected (<0,005 ppb), up to 0,41 and 0,66 ppb respectively, three months after and immediatly after the end of the period of insecticide application. For the lakes, the highest detected level was 0.9 ppb. Neither a relationship between the residual levels of BHC in the rivers and the sampling period, nor a regular increase in the residual levels in the direction river-source to river-mouth or vice-versa were detected, but just random variations from place to place in the same river. The maximum levels reached, although relatively high for organochlorides in water, are still lower than the levels accepted by the Brazilian laws for drinking water and than the levels tolerated for the survival of the majority of fresh water fishes.
| Main Authors: | , |
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| Format: | biblioteca |
| Published: |
1986
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| Subjects: | ZONAS CACAOTERAS, RIOS, LAGOS, POLUCION DEL AGUA, RESIDUOS, INSECTICIDAS, COMPUESTO ORGANICO DEL CLORO, BAHIA, BRASIL, |
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| Summary: | By means of gas chromatography the residual levels of BHC (HCH) in six of the main rivers and in two lakes of the Cacao Region of Southern Bahia were determined. The water samples were collected at the end of and three months after the end of the period of insecticide application in the region. Each river was sampled at or before the beginning, at the middle and after the end of its course through the cacao region. For each river included in this study BHC residues were detected in at least one of the three sampling places; the levels varied from not detected (<0,005 ppb), up to 0,41 and 0,66 ppb respectively, three months after and immediatly after the end of the period of insecticide application. For the lakes, the highest detected level was 0.9 ppb. Neither a relationship between the residual levels of BHC in the rivers and the sampling period, nor a regular increase in the residual levels in the direction river-source to river-mouth or vice-versa were detected, but just random variations from place to place in the same river. The maximum levels reached, although relatively high for organochlorides in water, are still lower than the levels accepted by the Brazilian laws for drinking water and than the levels tolerated for the survival of the majority of fresh water fishes. |
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