Variation of physical and chemical parameters by emphasizing on Nutrients in Southern Coasts of Caspian Sea

Caspian Sea and its coastal areas are one of the most important ecosystems. There is great diversity associated with non-biological parameters of water, in this largest lake in the world. In this study the physical and chemical parameters, including nitrates, phosphate, temperature, salinity, dissolved oxygen, transparency, EC and pH were investigated. Sampling was performed in 2008 in thirteen regions from Astara to Khajenafas in the south coastal waters of Caspian Sea. There were three stations in each area and sampling was done from surface waters (5 and 10 m) from each station. In this study, the mean temperature, salinity, pH, EC, water transparency, dissolved oxygen, nitrate and phosphate were 19.6 ° C, 11.8 ppt, 8.7, 17.28 (mm/cm), 82.23 cm, 6.22, 0.061 and 0.014 mg/l, respectively. Maximum and minimum of nitrate levels were 0.154 and 0.007mg/l in Kyashahr and Astara, respectively. The peak level of phosphate concentration (0.062mg/l) was found in Bandar Torkaman and the minimum level (0.001 mg/l) was obtained in the Anzali and Nashtaroud. The results show that concentrations of nitrate and phosphate were higher in south-east compared with south-west coast of the Caspian Sea. There was a significant difference in nitrate concentration in different regions (P< 0.05), but there was no significant difference in the concentration of nutrients in the water column (p>0.05). Results indicate that an increase in level of nitrate was found in compared to previous years. There were positive correlations in dissolved oxygen with nitrate levels and negative correlations with temperature and water transparency. Temperature, salinity and EC had positive correlation and the correlation of temperature with dissolved oxygen was negative.