Heavy metals content and distribution in soils in relation to soil hygiene

In the paper are discused total contents of heavy metals (Zn, Cu, Pb and Cd) in nine Slovak soil subtypes as well as their determination after extraction in 2M HNO3 or extraction either in 0.05M EDTA or in 0.01M CaCl2. The choice of the soil subtypes was concentrated on the lowland regions in south-eastern part of the Slovak Republic. For comparision were analyzed soils from mountain regions Stredny Spis and Prievidza, soils contamined by heavy metals of metallurgical factory (Kovohuty Krompachy) or by geochemical anomalies. Soil samples were taken from three soil horizons (0 - 0.1 m, 0.0 - 0.3 m and from 0.35 - 0.45 m) to determine anthropogenic or geochemical origin of heavy metals. The analized soils are characterized by parameters generaly regarded as crucial for heavy metals mobility (soil pH/KCl, humus content and ration of humic to fulvoacids). Soil pH-value is from very acid (pH 4.4) to neutral (pH 7.1). Cadmium content in lowland regions is manyfold higher than clark's (world background value). Similar results were obtained in the Czech Republic and other European countries. The definite immission load and natural endogenous anomalies are found in the region of Stredny Spis in Eutric Cambisols. The high contents of copper, cadmium, zinc and lead are also typical for this region. Differences in relatively high solubility in all extractans for all determined elements in heavy contamined Cambisols of mountain region Stredny Spis are discussed. The only exception is solubility of chromium in 0.05M EDTA and 0.01M CaCl2. The solubility scale from 70.6% for copper to 3.3% for chromium in Eutric Cambisols was determined in 2M HNO3. The limited suitability of this extractans is therefore for evaluation of potentialy mobilizable heavy metals. The importance of the determination of mobile forms (extract of 0.01M CaCl2) of heavy metals is controversial because of the low (trace element) contents which are very demanding in terms of the analytical determination. Cadmium has got relatively higher representation in mobile forms and it is especially valid for highly contaminated Eutric Cambisols, Haplic Chernozems, Eutric FLuvisols and Mollic Fluvisols. The universal extractant should not be expected for the evaluation of heavy metals mobility in soils. The relatively best is 0.05M EDTA especially for cadmium, lead and partially for zinc. The evaluation of heavy metals content extracted by different extractans in different pH values, humus content and its different quantitative composition should not be definite and relationships are usually lost in framework of futher soil characteristics