One of the aims of topsoil geochemical investigation of enterprises of various type industry as well as of energetics and transport is to determine the group of chemical elements that are polluting the territory, the degree of this contamination and the relationships between these elements. This is realized by comparing the determined quantities of chemical elements with their local background values and by distinguishing technogenical associations of chemical elements (their groups with high positive correlation bonds)including those that are typical for the enterprise. The latters help us to evaluate the zone of contamination of the enterprise. Samples are taken from the upper soil layer (1-10 cm), each of them representing 100-900 sq.m area (scale 1:1000-1:3000). Fraction <1 mm is used and the main analytical method is DC Arc Emission Spectrometry. Sorted factor loading matrix obtained by principal component analysis and varimax rotation is used for distinguishing of associations of elements.
Two main associations are distinguished in uncontaminated soils with the help of factor analysis : lithogenic (Ga-Li-B-V-Sc-Ni-Co-Cr) and clastogene (Zr-Ti-Y-Yb-Nb).They are characterized by high loadings on the main factors. In technogenically contaminated soils these associations usually contain lower number of elements and have loadings on less significant factors. New technogenical associations appear that mainly depend on technological processes taking place in the sources of pollution.
Typical associations can be revealed in enterprises with rare and specific technological processes and intensive
contamination, especially if the enterprise is isolated from the others. Sometimes specific elements can be included not in the group of pollutants that form high loadings of the main 2 factors but can be distinguished as loadings of a factor with lower percent of total variance. These elements can be called indicators of technological processes and are usually characterized by relatively high coefficients of concentration. Their examples are given in first two rows of Table 1. But
often the polluting elements are united in the first or second factor and their number is very large. In this case specific contamination of the enterprise can be determined analysing the descending sequence of median or mean values of coefficients of concentration (Kk)of the elements in the assotiation. The greatest among them can be considered as indicators of technological process of the enterprise. Their examples are given in bold in last three rows of Table 1. Various sources of contamination can also be identified by characteristic relation between Kk values of some typical elements. Usually in topsoils of transport enterprises Kk(Pb)>Kk(Sn)and on the territories of thermal electric power stations burning mazut Kk(Ni)> Kk(Zn). The analysis of the structure of association should also help to identify the enterprise.
If the activity of the enterprise is characterized by one main technological process then in most cases with the help of elements-indicators of technological processes or using specific technogenical associations the source of contamination can be identified and its zone of contamination can be distinguished. In those cases when the enterprises are close to each other and their technological processes are similar there is no possibility to do this with the help of the above mentioned methods.
Table 1: Indicators of technological processes.
Factor, its main loadings, Characteristic technological process
descending Kk sequence
F4: La-Ce Production and polishing of special glass for
television tubes (plant in Panevéz˜ys)
F4: V-Ni Mazut burning(Elektrënai)
F1:V-Cr-Ni-W-Co-As-Mo-Sn-Mn Ferrous metal processing
Kk:W>Mo>Cr>Co>V>Ni>As>Sn>Mn (plant of productionof drills in Vilnius)
F1:Sn-Cu-Zn-Ag-Ni-Cr-Pb-B Radio engineering
Kk:Ag>Cu>Zn>Sn>Pb>Cr>Ni>B (plant in Vilnius)
F2:Sb-Li-Ba-Pb-Sr-As Production of special glass and use of enamel
Kk:Sb>Pb>Sr>Ba>Li>As (plant "Ekranas" in Panevéz˜ys)