Zone

of the water body

Major chemicals, trace elements

Biogenic

substances

Pollutants

Pelagic areas

Trophogenic layer

10 - 12

7 - 10*)

5 - 7

Deep water zones of three basins

10 - 12

7 - 10

5 - 7

Bottom layers

10 - 12

10 - 12

7 - 10

Anthropogenic impact areas, near-delta areas of major tributaries

Trophogenic layer

7 - 10

5 - 7*)

3 - 5