Caspian Sea 2011
Table 4. The average annual load of pollutants in the apex and on the Volga delta seashore line (adapted from CEP, 2006 b).
Delta sea- shore line total (1995- 2004)
including western part
Delta Apex (1977-1993)
Delta Apex (1995-2004)
including eastern part
thousand tonnes thousand tonnes thousand tonnes thousand tonnes thousand tonnes thousand tonnes
9.45 1.66 1.49 439 311 273 186 122 15,4
tonne tonne tonne tonne tonne tonne
3 710 1 320
Note: For calculation of pollutant flows for delta seashore line, their concentrations in the central part of delta were used.
Water pollution Korshenko and Gul (2005) reported the results of pollution monitoring - Table “Average concen- tration of pollutants in the waters of the North Caspian Sea from 1993-2002” gives values for the average concentration of pollutants in the north- ern part of the Caspian Sea for the period 1993- 2002. The monitoring revealed that the levels of petroleum hydrocarbons were high in the 1980’s especially in the estuary of the Ural River and on the boarder of the Dagestan shelf. In the later part of the monitoring period, the levels were found to decrease and only occasional patches of high concentration. These high values were found in offshore areas of the Northern Caspian Sea, indi- cating that river, especially Volga, input may not have been responsible. Phenol concentration was detected rather high and showed significant varia- tions both in space and time. The long-termmoni-
the large quantity of degradable waste, including sewage and agricultural waste, has caused a de- cline in dissolved oxygen, especially in the deeper layers. During the period of the study from 2004 - 2005, the lowest levels were observed in the au- tumn when dissolved oxygen varied from 7.1-10.9 mg/L in the surface water, reducing to less than 5 mg/L at 160 m depth. Zaker concluded that these conditions were unfavorable for biological activ- ity and fish below 150-200 m and that measures needed to be taken to reduce the amount of oxy- gen demanding waste and plant nutrients enter- ing the Caspian Sea in this region. The pH levels of the Caspian are generally high, due to alkaline river inflows. They have been observed to average 8.3 to 8.6 in the sur- face layer and decrease to 7.8 to 8.0 at depth (Butts and Bradshaw, 1999).
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