Start up of the Baikal Pulp and Paper Plant (BPPP) in 1965 posed the problem of preserving the ecosystem of the Lake Baikal most urgently. Baikal was included on the UNESCO World Heritage List in 1996. Despite the executive orders directed at protect ing the ecological system of Lake Baikal, by reducing the anthropogenic influence on the ecological system of the lake that was developed in the USSR and Rus sian Federation, great success was not achieved. The lake is still polluted by substances from the river, atmo sphere, and, over 50 years, from waste discharge.Since the first year of the plant's existence, the Hydrometeorology and Environmental Monitoring Agency has monitored the waters of the lake in the area of the plant, and in 1969 it developed a system of permanent hydrochemical, geochemical, and hydro biological monitoring that incorporates the water sys tem, bottom sediments, atmospheric precipitation, and rivers flowing into the lake. Studies were carried out with use of several hundred stations located over the lake and on its northern and southern banks (impact area of the Baikal Amur railway) in the Selen ginsk shallow waters at background points where pol lution was relatively weak.Development of chemical analyses of complex organic compositions allowed scientists to make the first determinations of polycyclic hydrocarbons in the water of the lake, waste waters of the plant, and bottom sediments since the 1980s.The main objective of monitoring is to determine the total concentration of the PAH and benz(a)pyrene, the most toxic PAH, which is the most dangerous for the lake environment. The latter is an indicator in the waste waters of the plant, water of the lake, and bottom sediments in the area of the waste water discharge of the BPPP (polygon). Benz(a)pyrene is not the main polluting substance in the area of anthropogenic influ ence caused by waste waters from the sulfite cellulose industry of the plant on the ecological system of the lake. However, benz(a)pyrene is formed directly in the process of thermal processing of wood under tempera tures of 300-400°C , and in the course of monitoring, it is an important indicator of pollution of bottom sed iments in the described polygon of the plant [1].Samples of bottom sediments in the area of the waste water discharge of the plant in the polygon with area of 20 km 2 were collected at 9-40 stations with use of the Ocean 0.05 dredge (made of stainless steel) from the surface layer of bottom sediments (pelogenous) at a depth of 20-500 m. Samples were placed into plastic pockets and immediately delivered to the laboratory. Then samples were dried at a temperature of 105°C and stored at room temperature before the analyses. Polycyclic aromatic hydrocarbons were extracted from the samples of bottom sediments with use of benzol over 8 hours in the Soxhlet device. Benzol was distilled off with the use of a rotary evaporator, and extraneous impurities were removed from the residue with use of the method of thin layer chromatography. Hydrocar Abstract-New data o...