Radioactive Contamination of the Neva River-Lake Ladoga Aquatic System
Many-year monitoring data on the 90Sr and 137Cs levels in water of the Neva River and Lake Ladoga are presented. In 1970-1990, the 90Sr level in the Neva River steadily increased. In 1991, a radiological survey was made of the Kit experimental vessel with radioactive wastes in its holds, which was on berthing in the northwesteren part of Lake Ladoga. 90Sr, 137Cs, and 239,240Pu were monitored in water and bottom sediments near the Kit vessel berthing after it was towed outside Lake Ladoga. In 2001, the 90Sr concentration in water of Lake Ladoga and the Neva River considerably decreased.