Sedimentos contendo altas concentrações de metais pesados em reservatórios, lagos e rios, podem ressuspender no ambiente aquático e impactar negativamente na qualidade da água. A concentração de 10 elementos foi estudada em sedimentos superficiais e na água do reservatório Aguada Blanca, Peru, uma importante fonte de água para 1.080.000 pessoas na árida província de Arequipa. Foram determinados o enriquecimento, acúmulo, risco ecológico e distribuição de metais no sedimento, enquanto as informações de metais pesados na água foram utilizadas para corroborar a qualidade do sistema aquático. Amostras de sedimentos e água foram coletadas em nove pontos em 2019. Espacialmente, os metais pesados apresentaram variações ao longo da área de estudo com aumento para a maioria dos elementos próximos à parte mais profunda do reservatório. A concentração média de Cd no sedimento foi 4 vezes maior do que o fundo natural. Na água, o As foi o único elemento que ultrapassou as regulamentações peruanas (As > 10 μg L-1). O Fator de Enriquecimento (EF) e Índice de Geoacumulação (Igeo) dos metais no sedimento apresentaram a seguinte ordem: Cd>As>Pb>Zn>Cu>Ni>Cr, sendo Ni e Cr os únicos elementos que não apresentaram enriquecimento. O Igeo mais expressivo foi o Cd (1.21 ± 1.45), apresentando uma classificação de moderada a fortemente contaminada. O risco ecológico potencial integrado (RI) do Cd apresentou valores elevados em 5 pontos do reservatório. Os resultados encontrados fornecem informações necessárias para estabelecer estratégias de controle sobre a qualidade do sistema aquático.
Palavras-chave: metais pesados; qualidade da água; reservatório; sedimentos
Sediments containing high concentrations of heavy metals in reservoirs, lakes and rivers, can resuspend into aquatic environments and negatively impact water quality. The concentrations of 10 elements were studied in surface sediments and water from the Aguada Blanca Reservoir, Peru, an important water source to 1,080,000 people in the arid province of Arequipa. Sediment and water samples were collected from nine points in 2019. The enrichment, accumulation, ecological risk and distribution of metals in sediment were determined, and the information on heavy metals in water was used to assess the quality of the aquatic system. Spatially, heavy metals showed variations throughout the study area, with an increase for most elements near the deepest part of the reservoir. The average concentration of Cd in sediment was 4 times higher than the natural background. In water, As was the only element that exceeded Peruvian regulations (As > 10 μg L-1). The Enrichment Factor (EF) and Geoaccumulation Index (Igeo) of metals in sediment presented the following order: Cd> As> Pb> Zn> Cu> Ni> Cr, with Ni and Cr being the only elements that did not present enrichment. The most considerable Igeo was Cd (1.21 ± 1.45), presenting a classification of moderately to heavily contaminated. The integrated potential ecological risk (RI) of Cd presented high values in 5 points of the reservoir. The information developed will assist in establishing effective control strategies for the quality of the aquatic system.
Keywords: heavy metals, reservoir, sediments, water quality
Sediments containing high concentrations of heavy metals in reservoirs, lakes and rivers, can resuspend into aquatic environments and negatively impact water quality. The concentrations of 10 elements were studied in surface sediments and water from the Aguada Blanca Reservoir, Peru, an important water source to 1,080,000 people in the arid province of Arequipa. Sediment and water samples were collected from nine points in 2019. The enrichment, accumulation, ecological risk and distribution of metals in sediment were determined, and the information on heavy metals in water was used to assess the quality of the aquatic system. Spatially, heavy metals showed variations throughout the study area, with an increase for most elements near the deepest part of the reservoir. The average concentration of Cd in sediment was 4 times higher than the natural background. In water, As was the only element that exceeded Peruvian regulations (As > 10 μg L-1). The Enrichment Factor (EF) and Geoaccumulation Index (Igeo) of metals in sediment presented the following order: Cd> As> Pb> Zn> Cu> Ni> Cr, with Ni and Cr being the only elements that did not present enrichment. The most considerable Igeo was Cd (1.21 ± 1.45), presenting a classification of moderately to heavily contaminated. The integrated potential ecological risk (RI) of Cd presented high values in 5 points of the reservoir. The information developed will assist in establishing effective control strategies for the quality of the aquatic system.
Keywords: heavy metals, reservoir, sediments, water quality
