River pollution in ladoga basin: Estimation based on diatom index

A modification of water stream pollution index was developed based on the use of periphyton diatomic algae, taking into account the regional features of the Ladoga basin. Original values of indicator valences and weights are given for 60 mass taxa of diatoms. River water quality was found to deteriorate from the north to the south because of the higher economic development of the southern part of Ladoga basin. The zonal changes in water quality in large rivers is much less pronounced than in medium and small rivers, which have closer relationships with the local situation on the watershed. Studying the correlation of the modified index with total phosphorus concentration showed it to be more efficient in estimating the anthropogenic pollution of streams in Ladoga basin as compared with trophic datomic indices developed in Europe.