The study of water quality fluctuations of Aras reservoir

Aras reservoir is situated at 38 km of Poldasht with the capacity of 1350 million m3 water and it is very important for biological and economic exploitation. This study was carried out to determine thewaterphysic- chemical factors of Aras reservoir 7 selective sites were sampled (3 sites in the river, 2 sites at entrance and 2 sites at the outlet of the river) monthly during April to September, 2008. Water samples were transferred to the laboratory under standard condition and examined according to standard method. The results showed that maximum level of Ammonia, Nitrate and Phosphate were observed as 0.582, 49 and 4 mg/l in the river, where maximum level of Nitrite was observed as 0.24 mg/l at reservoir outlet. In addition, maximum of E.C. and T.D.S. were observed as 1070 µmohs/cm and 797 mg/l at entrance and minimum of E.C. and T.D.S. were observed as 128 and 180.7 mg/l at outlet of the river, respectively. The ANOVA Duncan test revealed that the phosphate, nitrite, nitrate, non ionized ammonia factors in different sites and nitrite, nitrate, non ionized ammonia, temperature, pH, TDS and EC in different times of sampling had a significant difference ( P