Accumulation of trace elements in A. persicus tissues in relation to feeding habits and mode of absorption of these pollutants

Bioaccumulation of heavy metals Cd, Pb, Cu and Zn in muscle tissue and organs (gills, liver, kidney and stomach) in A. persicus was studied in the ‘Iranian fishery zone 1’ lying between Astara (48? and 52' east longitude and 38? and 26' north latitude) and Kiyahshahr (49? and 53' east longitude and 37? and 27' north latitude). Samples were collected from five catch stations in the study area during the autumn catch season in 2001. A section of pectoral fin ray was removed for age determination. Samples were analyzed by wet digestion with hydrogen peroxide and nitric acid). Analyses were testified using spike method. A sample of cow liver (CMR 185R) was also tested to ascertain reliability of analyses. Digested samples were analyzed chemically using Flame Atomic Absorption Spectrophotometer (Varian spectra). Statistical analysis of results was carried out using ANOVA, Duncan’s test and test of clusters to determine differences between the mean concentrations of metals in terms of tissue, sex and region. The bioaccumulation pattern for Zn in different tissues studied was stomach>liver>kidney>gills>muscle tissue. Mean concentrations for Zn in the stomach was 136.6 ± 10.70 µg g -1 dry weight and belonged to a separate group as compared with other tissues (sig. Level 0.0000, F=26.6). However no significant differences were observed in the concentration of Zn in terms of other factors (sex, age, catch station). Cu with the maximum concentration of 39.71 ± 8.85 µg g -1 dry weight in liver showed a bioaccumulation pattern of liver>kidney>stomach>gills>muscle tissue. On the basis of Tukey test liver belongs to a separate group in terms of Cu concentrations. The bioaccumulation pattern for Pb was determined as gills>liver>kidney>stomach>muscle tissue. Maximum mean concentrations of Pb 6.87 ± 2.25 µg g -1 dry weight belonged to gills. According to Tukey test significant differences were observed among the various tissues studied regarding concentrations of Pb. Bioaccumulation pattern for Cd in the different organs studied in A. persicus was kidney>liver>gills>stomach>muscle tissue. Maximum mean concentration of 5.1 ± 0.97 µg g -1 dry weight belonged to kidneys and the minimum mean concentration of 0.05 ± 0.007 µg g -1 dry weight belonged to muscle tissue. On the basis of international standards the concentrations of Cd in muscle tissue are lower than the maximum allowable concentration (MAC) for this metal for human consumption. Concentrations for Cd are lower than MAC in some organs and are higher than MAC in other organs studied. The observed concentrations do not pose health problems as these organs are not used for human consumption. However they may cause problems in terms of histology and physiology and need to be studied further. The accumulation pattern for metals in sediment samples in the study regions was Zn>Pb>Cu>Cd. The concentrations for metals determined in sediment samples collected at 10 and 15 m depths in the present study are lower than levels that are considered harmful to the environment.

Iranian Fisheries Science Research Institute

Published