An assessment of the pollution of heavy metals in Jacarepagua basin, rio de Janeiro, Brazil: A statistical approach

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Abstract
The paper presents the metal pollution assessment of Jacarepaguá basin rivers and lagoons based on statistical analysis of metal concentration in bottom sediments. It is demonstrated that Pavuna and Fundo Creeks are the main sources of anthropogenically introduced metals to the lagoons. Due to the weak process of water circulation in the lagoons the contamination is restricted to the discharge areas of both rivers. Metal concentration in river sediments appears to be highly dependent on rainfall events thus a seasonal (wet and dry seasons) variation in their concentration can be proposed. The examination of metal lognormal distribution plots indicates that concentration values, related to the curve inflexion(s), can be operationally used as thresholds between polluted and unpolluted areas. These values were; 0.92 μg g‐1 for Cd, 165 (μg g‐1 for Zn, 15 μg g‐1 for Cr and 26 μg g‐1 for Ni. Factor analysis was used to examine the main sources of metals to the aquatic environment. It can be suggested that the steel and chemical industries would be the most important sources of metals released to the aquatic environment.