Determination of Heavy Metal Content in Astacus leptodactylus caspicus of Anzali Wetland, Iran

Abstract

With attention to different human activities around Anzali wetland and introduction of different pollutants containing heavy metals into this water ecosystem and absorption and accumulation of heavy metals in shell and muscle of Astacus leptodactylus which is native benthose of Anzali wetland and enjoys food and economic importance; Sampling of waters and sediments from 18 stations and shell and muscle of Astacus leptodactylus from 5 stations had been conducted. After biometric evaluation of Astacus leptodactylus, the chemical analysis of the samples by using international and standard methods and then their heavy metals content was determined by Atomic Absorpotion Spectrophotometer (AAS), model P.U 9400 philips. Result of the analysis stated that; 1) The mean values of Cr, Zn, Pb, Ni, V in Anzali waters were 6.4, 184.5, 28.8, 28.9, 47.1 (<TEX>$\mu$</TEX> gr/lit) respectively, which comparing to the international standards, is not suitable for drinking, but it can be used for agricultural and aquacultural purposes. Even though the concentration of heavy metals in sediments were high, there are in range of acceptable limit for aquatics organisms; 2) Comparatively, the concentration of heavy metals in shell and muscle of Astacus leptodactylus in Anzali wetland (Cr, Zn, Pb, Ni, V in shell were 3.48, 109.3, 14.13, 7.17, 36.2 and in muscle were 2.98, 131.98, 3.12, 4.77, 9.05 ppm respectively) were more than what is determined for Aras dam (in shell were 1.6, 224.3, 7.8, 7.6, 10.3 and in muscle were 1.4, 60.2, 0.45, 2.7, 4.4 mg/kgr respectively); 3) For all samples, concentration of heavy metals in all Astacus leptodactylus in Anzali wetland and Aras dam, was at tolerance level for human consumption; 4) There was no association with significant difference between weight and size of Astacus leptodactylus with absorption and accumulation of heavy metals; but there was a significant association between heavy metals content in water and in sediments, and in sediments, shell and muscle of Astacus leptodactylus in Anzali wetland.