In Lithuania geochemical mapping of urban areas was started in Vilnius city in 1985. Topsoil, stream sediments, snow cover, manufactory dust and other sampling media are used in ecogeochemical investigations. The aim of investigations is to detect sources of pollution, its geochemical properties and spread of its contamination. Furthermore, a sanitary assessment of urban soil is carried out on the basis of available geochemical data and the soil quality standard of Lithuania HN 60:2004. The soil contamination with heavy metals is estimated according to the highest allowable concentrations (HAC) and the total contamination index Zd which is related to the criteria of human health. At present the geochemical data on soil contamination in the areas of Vilnius, Panevëžys, Mažeikiai, Šiauliai, Alytus, Biržai, Pasvalys, Rokiškis, Kupiškis and other towns are in store of the geochemists of Geological Survey of Lithuania and Institute of Geology and Geography. The soil geochemical background values obtained by geochemical mapping of natural areas are always used for assessment of contaminated urban areas. Part of geochemical background and contamination data is published in Geochemical Atlas of Lithuania. Some geochemical data and soil contamination maps are in use of town municipalities on order and funds of which the geochemical investigations of urban areas were performed. However, geochemical investigations lag behind the planning, development and reclamation projects of urban areas, thus, new dwelling houses are often built on hazardous contaminated sites that may make a threat against human health.
MAPPING OF GEOCHEMICAL CONTAMINATION IN URBAN AREAS OF LITHUANIA
