Caspian Sea: State of the Environment 2019

and slightly less than 10 per cent into water bod- ies in Astrakhan Oblast. An average of 0.11 km 3 of polluted wastewater per year was insufficiently treated before being discharged into water bodies over the same pe- riod. Almost 60 per cent of this was discharged into water bodies in the Republic of Dagestan, over 40 per cent into water bodies in Astrakhan Oblast, and less than 1 per cent into water bodies in the Republic of Kalmykia (Figures 4.7, 4.8). Pollution of precipitation By observing the pollution of precipitation from the integrated background monitoring station on the Caspian coast (in the Damchik area of the Astrakhan Biosphere Reserve), it is possible to estimate the flow of pollutants from the atmo- sphere to the sea surface (Table 4.3). Assuming that 100 mm of precipitation falls annu- ally on the water area adjacent to the Russian Fed- eration (which is close to the actual figure), and that this water area covers an area equal to the area of the bottomof the Russian Federation sector (63,400 km 2 ), then the amount of precipitation falling on this water area annually will be 6.3 km 3 . Data on the concentration of pollutants in precipitation is available and so calculating precipitation flow from the atmosphere to the sea surface is straightfor- ward. Comparison of pollutant volumes entering the sea with river run-off and with precipitation have shown that for a number of substances (for example, mercury), similar volumes of pollutants enter the sea from the atmosphere and from river run-off, and the amount of DDT entering the sea

Wastewater discharge into the Caspian Sea

million m 3

The Republic of Kalmykia Total

Astrakhan Oblast The Republic of Dagestan

Untreated polluted wastewater

million m 3

The Republic of Kalmykia Total

Astrakhan Oblast The Republic of Dagestan

Insufficiently treated wastewater

million m 3

River run-off

Precipitations

The Republic of Kalmykia Total

Astrakhan Oblast The Republic of Dagestan

Figure 4.8: Discharge of wastewater into the Cas- pian Sea and rivers flowing into it, 2012–2016 From the territory of Astrakhan Oblast, the Republic of Dagestan and the Republic of Kalmykia. Source:RussianFederation,MinistryofNaturalResources2017.

Mercury Copper

DDT

y-HCH

Lead

Figure 4.9: Pollutants entering the sea with at- mospheric precipitation and with river run-off (in comparable units)

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