Soil geochemical mapping of the central part of Prague, Czech Republic

Abstract

New geochemical mapping results from the central part of Prague agglomeration are presented. The study is part of the EuroGeoSurveys Geochemistry Expert Group's ‘Urban Geochemistry’ (URGE) project. The aim of the project is to study and compare the level of potential hazardous trace element contamination in the topsoil of European cities. For such a comparison, standardised sampling, sample preparation and analytical methodologies were used in almost all URGE project surveys.Topsoil samples were collected at 194 sites from the Prague city centre. Concentrations of elements in samples taken at different distances from busy roads were evaluated, and a group of traffic related elements (Ag, Au, Ba, Cd, Cr, Cu, Mo, Nb, Pb, Pd, Pt, Sb, Sr, Sn, W and Zn) was distinguished. Element relationships, based on land use (traffic affected areas, parks, residential and other urban facilities) were studied. The traffic related element group trend is manifested most significantly in the traffic affected, residential and other urban facilities categories. Another significant trend in element concentrations from a different source is from the burning of fossil fuel (As, Be, Co, Cr, Cs, Fe, Ga, K, Mg, Ni, U, Ti and V).Concentration of elements in the topsoil of the city's parks are compared with grazing land soil in the Czech Republic, using the results from the EuroGeoSurveys project of geochemical mapping of agricultural and grazing land soil (GEMAS). Three basic groups of elements were distinguished. The first group includes elements with concentrations that are higher in Prague parks compared to grazing land soil (Ag, As, B, Ba, Be, Bi, Ca, Cd, Cu, Hg, Mo, Na, Nb, Ni, P, Pb, S, Sb, Sn, Sr, W, Zn); the second group has comparable concentrations in both soil types (Co, Cr, Fe, K, Mn, Sc, Se, Ti, U, V, Y), and the third has lower concentrations in Prague parks soil (Al, Ce, Cs, Ga, Hf, In, La, Li, Mg, Rb, Te, Th).It is concluded that there are elevated concentrations of potential harmful elements in the topsoil of the central part of the city of Prague, and their bioavailability should be studied.