2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures
2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures
2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures
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Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology<br />
P76 DISTRIbuTION OF hEAVy METALS IN SOILS<br />
TOMአTóTH, JURAJ ČéRY, Ján TOMáŠ, ALEnA<br />
VOLLMAnnOVá and PETER LAZOR<br />
Department of Chemistry, Faculty of Biotechnology and Food<br />
Sciences, Slovak Univeristy of Agriculture, Tr. A. Hlinku 2,<br />
949 01 Nitra, Slovak Republic,<br />
tomas.toth@uniag.sk<br />
Introduction<br />
The soil quality is derived from its loading by hazardous<br />
substances. The loading of soil occurs when the soil is not<br />
able to lower the negative influences of the heavy metals. The<br />
reference value, which represents natural content of heavy<br />
metals in soil, forms the basis for evaluation of the content of<br />
heavy metals in soil. The important parameters for the input<br />
of heavy metals from soil into plants are: the soil reaction,<br />
the content and the quality of organic matter, the nutrition<br />
of plants, cation exchange and sorption capacity, the microbiological<br />
activity, the oxidation and reduction potential, the<br />
amount and the quality of the clay fraction of soil and the<br />
methods of soil cultivation, etc.<br />
Experimental<br />
The hazardous heavy metals were determined in eight<br />
soil subtypes. Their choice was concentrated on the lowland<br />
regions (Trnovec n/V. – haplic chernozems, Imeľ – eutric<br />
fluvisols, Čičarovce – luvic stagnosols, Dolný Štál – mollic<br />
fluvisols, Veľké Leváre – haplic arenosols, Malanta – haplic<br />
luvisols). We took four parallel soil samples to be able to examine<br />
the soil homogenity of the monitored area. The samples<br />
from the pedological probe were taken from the depth<br />
of 0–0.1 m; 0.20–0.30 m; 0.35–0.45 m. The state of the soil<br />
hygiene was examined by evaluation of the total contents of<br />
Cd, Pb, Cr, Cu and Zn. The total contents were determined after<br />
the mineralization by wet way H 2 SO 4 , HnO 3 and HClO 4<br />
using the method of atomic absorption spectrometry. We also<br />
determined the heavy metals in the pedological probe to be<br />
able to estimate the anthropogenical and geochemical origin<br />
of the heavy metals. The above mentioned heavy metals<br />
were determined in the extract of 2M HnO 3 and in cold. The<br />
mobilizable forms of heavy metals were determined in the<br />
extract with 0.05M EDTA. The mobile heavy metal forms<br />
were determined in extract of 0.01M CaCl 2 .<br />
Results<br />
The valid legislation was used for the evaluation of soil<br />
hygiene. The evaluation is influenced by determination of the<br />
total contents of heavy metals and by the determination of<br />
heavy metals in 2M HnO 3 leach. Contents of heavy metals<br />
in 2M HnO 3 ; 0.05M EDTA and 0.01M CaCl 2 and the percentage<br />
abundance of Zn, Cu, Cr, Pb and Cd in individual<br />
extractants. The following order of extractability for individual<br />
extractants is evident. The results of determination<br />
of actual mobilizable forms are considered to be the most<br />
acceptable. The percentage contents of individual heavy<br />
s493<br />
metals and the total content of heavy metals in highly contaminated<br />
soil are as follows: Zn 1.7–13.9 %; Cu 14.1–6<strong>2.</strong>6 %;<br />
Cr 0.1–1.3 %; Pb 14.6–24.1 %; Cd 1<strong>2.</strong>9–2<strong>2.</strong>8 %. EDTA and<br />
natrium and ammonium of EDTA are able to form stable<br />
and defined complexes with heavy metal cations and they<br />
cause the solubility of carbonates and oxides Fe and Al. The<br />
exctracted contents of heavy metals were measurable during<br />
the use of flame AAS. The mutual interactions of Zn, Cu, Cr,<br />
Pb and Cd with the soil components influence the pH value,<br />
content and quality of organic substances. Apart from the<br />
above mentioned soil properties, there are many other variable<br />
soil properties. The lowest Zn solubility was determined<br />
in subtypes of luvic stagnosols and eutric cambisols with pH<br />
values in the acid part and the quality of mould expressed<br />
by the ratio of humic acids to fluvic acid was the lowest but<br />
on the other hand the percentage of mould has one of the highest<br />
values. The solubility of Cu in 2M HnO 3 and in 0.05M<br />
EDTA was in all soil subtypes the highest and it is especially<br />
valid for haplic arenosols, haplic chernozems, mollic fluvisols<br />
(FL m ). The order of solubility for the determined elements<br />
and and extractants was as follows: 2M HnO 3 > 0.05M<br />
EDTA > 0.01M CaCl 2 .<br />
The lowest amount of Cd and Pb from haplic arenosols<br />
(RM g ) were extracted by extraction with 2M HnO 3 and<br />
0.05M EDTA and the highest amounts of Cd were obtained<br />
from mollic fluvisols, haplic chernozems. The evaluation of<br />
heavy metal contents extracted from individual extractants<br />
at different pH values, the content of mould and its qualitative<br />
composition is not unequivocal and dependence between<br />
variable soil properties and conditions of environment<br />
disappear.<br />
The solubility of Cu in 2M HnO 3 and in 0.05M EDTA<br />
was in all soil subtypes the highest and it is especially valid<br />
for haplic arenosols, haplic chernozems, mollic fluvisols.<br />
The order of solubility for the determined elements and and<br />
extractants was as follows: 2M HnO 3 > 0.05M EDTA > 0.01M<br />
CaCl 2 . We think that the best extractant is 0.05M EDTA with<br />
restriction to Cd, Pb, Cu and partially for Zn. It is not possible<br />
to find an universal extractant for evaulation of heavy metals<br />
mobility in soil.<br />
Conclusions<br />
(i)The extractability for individual ectractans is evident:<br />
2 mol dm –3 HnO 3 : Cu > Cd > Pb > Zn > Cr; 0.05 mol dm –3<br />
EDTA: Cu > Cd > Pb > Zb > Cr; 0,01 moldm –3 CaCl 2 :<br />
Cd > Cu > Pb > Zn > Cr. (ii) It is necessary to emphasize the<br />
differences in solubility between the highly contaminated<br />
eutric cambisols of Stredný Spiš and other analyzed soils.<br />
The different solubility is in all extractants and heavy metals<br />
except the solubility of chromium in 0.05M EDTA and<br />
0.01M CaCl 2 . It is probably connected with the high portion<br />
of heavy metals of immissional origin. The other analyzed<br />
soil subtypes have a low solubility of Zn in HnO 3 and EDTA<br />
in luvic stagnosols.