Comparison and Analysis of Spatial and Temporal Changes in Pattern of Seawater Components in Southwestern Continental Shelf and Deep Area of the Caspian Sea using Collected Data

In the study, spatial and temporal changes in pattern of seawater components in the western part of the southern continental self and deep area of the Caspian Sea were evaluated. The research was based on field data analysis that collected using CTD sensors from sea surface to a depth of 475 m. According to the results, it can be seen that the forming of a deep sound channel in the water column is possible. Vertical distribution of active reaction showed a general reducing trend with depth that reached to 8.2 at depth of 350 m in midsummer. Moreover, observations in November showed active reaction value of 8.3 at 450 m depth. In comparison, amounts of active reaction (pH) in mid-summer (August) were less than that in other seasons. Dissolved oxygen concentrations ranged between 2.0-7.5 mg L-1 at the surface layers. Below level of 100 m, a rapid drop in values of dissolved oxygen were observed and measured about 1.2 mg L-1 at 450 m depth in mid-summer and mid-autumn, while value of 2.0 mg L-1 was recorded below 300 m depth in late winter. The seasonal variations of dissolved oxygen and active reaction (pH) were considerable, especially in intermediate and deepwater layers. According to the obtained data seawater turbidity in winter and spring seasons was recorded more than it in summer and autumn. In most cases due to coastal factors and processes, seawater turbidity of onshore area was more than the offshore.