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Sequential extraction methods enable identification of chemical fractions of heavy metals in soil environment as well as evaluation of their availability and potential toxicity to biotic elements of a trophic chain. The study aimed at separating nickel fractions from particular genetic horizons of forest Luvisols by means of three sequential extraction methods (modified Tessier’s, Zeien and Brümmer’s as well as Hedley’s with Tiessen and Moir’s modifications methods), and to compare the metal content in four fractions: easily soluble, exchangeable, organic, and residual, along with their distribution within studied soils’ profiles. Nickel concentrations in the examined fractions varied: the largest amounts of the heavy metal (regardless of the analytical procedure applied) were found in residual fraction Fresid (mineral horizons) and organic fraction Forg (forest litter horizons – Ol), while the smallest ones occurred in easily soluble fraction F1 (all genetic horizons). Statistical processing revealed significant dependences between the four nickel fractions as well as between the fractions and selected properties of analyzed soils (except soil pH and total nickel content Nit).
The aim of our study was to estimate the influence of mineral fertilization on the contents of various copper and nickel forms in soil. It was based upon a field experiment made up of ten plots. In average soil samples taken in 2002-04, the pseudo-total copper and nickel content was determined. Chemical forms of these metals, by modified BCR method, were also determined. The nickel content in particular fractions can be arranged quantitatively (average values) in order as follows: F2 (21%) > F3 (18%) > F1 (8%), in the case of copper: F2 (37%)>F3 (14%)>F1 (11%). The accumulation of nickel in the soil during the experiment was not observed. Whereas slight copper accumulation in some plots (with Polifoska 6, Polimag 305, calcium sulfate tetraurea and phosphogypsum) was noted. During the experiment the most mobile nickel and copper forms (soluble + exchangeable fraction) increased.
The objective of the study was to evaluate the impact of liming and the application of waste organic material, i.e. sewage sludge, on the content and distribution of nickel in the fractions extracted with the BCR procedure from soil contaminated with this metal. The study was carried out on soil after a 3-year pot experiment, which included the following factors: I – nickel used in the incremental amounts 0, 50, 100 mg Ni kg-1 soil; II – liming (0 Ca and Ca according to 1 Hh of soil); and III – the addition of sewage sludge (with and without the addition of sewage sludge at the introducing dose of 2 g C kg-1 soil). The test plant was cocksfoot harvested four times (four swaths) in each plant growing season. The total content of nickel was determined with ICP-AES and its fractions with the three-stage BCR procedure. The introduction of nickel into the soil resulted in an increase in its total content and in all fractions as well as in its percentage in the exchangeable fraction. Liming reduced the mobility of nickel and decreased its content in the reducible fraction, whil inccreasing it in the residual fraction. The application of sewage sludge contributed to an increase in the total content of nickel in soil and its proportion in the oxidizable fraction. Liming and the application of sewage sludge reduced the mobility of nickel. Lime and waste organic material (i.e. sewage sludge) were found to be suitable materials for reduction of the mobility of nickel in soil contaminated with this metal.
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