Rimantė Zinkutė

Geochemical indices used to identify the emerging anomalies of potentially harmful elements in topsoil depend on background values (BVs). For urban sites, it is reasonable to estimate native BVs through the targeted selection of peri-urban sampling sites or by distinguishing a useful background subset (BS) within the peri-urban dataset. Here, the goals were to examine the influence of Quaternary deposits on various types of topsoil variables, identify the variables most helpful for cluster analysis intended for the choice of background subset (BS), and compare background values (BVs) based on different background subsets. Composite topsoil samples from a peri-urban area were used for the determination of the following variables: contents of 26 elements and components of the bulk mineralogical composition, as well as the sand, silt, and clay fractions and loss-on-ignition (LOI) at 550 °C and at 950 °C. Although Quaternary lithology influences topsoil elemental contents or granulometric fractions, percentages of illite, kaolinite, orthoclase, quartz, albite, dolomite, and LOI at 550 °C, the choice of BS, according to it, is not recommended, as BVs based on topsoil texture are superior. However, cluster analysis using topsoil fractions < 2, 63 μm or the contents of Al, Fe, K, Ti, Ga, Nb, Rb, and Si are preferable. It is recommended to use these reference variables for the selection of BS.

Geochemical investigations of total suspended particulates (TSP) help detect hotspots and emission sources in port cities with stevedoring operations. The aim was to reveal these sources via geochemical indices (gI). TSP were collected in Klaipėda using original passive samplers in ten sites during four periods, during one of them, in ten additional sites near iron ore stevedoring (IOS). The contents of 22 elements (PHEs, crustal, Br, Cl) were determined by EDXRF in TSP and characteristic dust (CD) of stevedored iron ore, apatite, phosphorite, potassium fertilizers, and in waste incineration ash. Median Fe content in TSP near IOS was ~29%. The significant anthropogenic origin of clusters Fe–Cr, Sr–P, V–Ni–Zn–Cu, Pb–As, and Mg–Ca, Br–S–Cl was confirmed by gI mapping and analysis of CD. Significant temporal variability of Cl, S, Sr, Ni, Br, V, and Zn due to weather changes was revealed. Near IOS, significantly higher values of gI were found for Fe and Cr, while far from IOS, for K, Sr, Ti, Rb, Cu, Al, Si, Zr, Ca, Mg. Significantly higher values of normalized enrichment factor near IOS were not only for Fe and Cr, but also for As, Pb, S, Mn, Br, and Cl.

This study of peri-urban minerogenic topsoil on glacigenic or post-glacial deposits shows the influence of the site-classification approach on the differentiated median background (DMB) values of major elements and the potentially harmful elements (PHEs) Ba, Cr, Cu, Mn, Ni, Pb and Zn. Composite samples from forests and meadows were taken in 25 sites, each of which had five sub-sites. A fraction of <2 mm was used to determine the organic matter by loss on ignition (LOI), grain size by laser diffraction and the elemental contents by X-ray fluorescence. The following five site-classification approaches are compared: geochemical (G), using relative median contents of Al, K, Ti; textural (T), according to mean percentages of clay-sized fraction (CLF) and silt fraction (SIF); lithological (L), based on soil parent material texture from the soil database; soil type (S), presented in the soil database; and parent material (P), generalising the underlying Quaternary deposits. Sites were classified into four level groups in which the DMB values were estimated after eliminating anomalies. The average ranks of three scores according to SIF, CLF, LOI, Al, K, Ti, Fe, Mg, Ca and S in the respective groups revealed the highest value for the G approach. It better eliminates the CLF and SIF influences on the median assessment indices of PHEs in sites.