Abstract
The Estuary Lagoon Mundau-Manguaba (ELMM), in the State of Alagoas is a very productive one and is located in Maceio, Brazil. In this estuary, two lagoons (Mundau and Manguaba) and some streams are connected with the Atlantic Ocean. Due to the input of nutrients, a very rich and highly productive ecosystem was generated, being the nutritional source for the local people. Among those organisms, the bivalve mollusk Mytella charruana has a huge nutritional significance, being very easy to catch. For this reason the elevated productivity of this mollusk is essential. The estuary has suffered the impact of some human activities and the most important are related to sugar cane, culture, sugar/alcohol production allied to MVC and PVC industries and in natura sewage release local cities, including the capital of the state, Maceio. The present work aims to evaluating lead concentration in the tissues of Mytella charruana, since those organisms can be used as biomonitors of heavy metals pollution. The mollusk was first washed with Water Milli-Q, until complete elimination of incrusted sediments. After removal of the soft tissue from the shells, with plastic spoons, excess humidity was eliminated using paper filter. Digestion was performed using 2.0 (? 0.0001) g (wet wt) of mollusk tissue in 10 mL of concentrated HNO3. After filtration through 0.45 |im membrane, the solution was made up to 100 mL using citrate buffer (pH 3). Lead concentration in the digest was determined by anodic stripping voltammetry, using square wave voltammetry. The mercury film was generated on a carbon vitreous surface (BAS) from Hg(NO3)2.H2O solution, with 5 minutes of deposition. The pre-concentration of the analyte was also of 5 min. In the optimized conditions (citrate buffer, pH 3), calibration curves were built with linearity between 3.5 and 160 ppb. The mollusk digest was analysed, yielding 1.7 |ig/g of Pb. Recovery tests in the sample were performed in the determination of Pb with addition of 360 |iL and after 550 |iL of one solution of 1 mg/L of Pb. The results obtained were 94 e 76% for the first and second additions, respectively. The used methods were adequate concerning extraction and Pb determination, in the analysis of mollusk Mytella charruana. The content of Pb in he mollusk does not compromise is use as a nutritional source.