Wpływ formy nawozów potasowych i magnezowych na mobilność metali ciężkich w glebie lekkiej

Changes in the mobility of Zn, Cd, Pb and Cu in medium sand soil depending on forms of salts: K₂SO₄ + MgSO₄ or KC1 + MgCl₂ were studied. Those salts were applied at varying soil pH-value (5,4; 6,2; 7,0). Studies were carried out in the leaching experiments using laboratory columns. Heavy metals were leached by simulation 600 mm of rainfall, over a 6 month periods. Leachates were collected and analysed every 200 mm portion of simulated rainfall. Concentrations of Zn, Cd, Pb and Cu in leachates showed that significant increment in the mobility of tested heavy metals took place during the first 200 mm portion of rainfall simulation. It was confirmed that applied salts caused increasing in the leachability of Cd about 35-100 times, Zn about 45-50 times, Pb about 5-10 times and Cu about 3-5 times, comparing to unfertilized soil at pH-value 5,4. Those ranges in the mobilization of heavy metals were significant lower in case of using sulphate salts than chloride salts. In case of Cd, Pb and Cu, the effect of sulphate treatments at lower pH-value (5,4) was compared to chloride-treated soil at higher pH-value (6,2). On the base of the electrical conductivity of leachates, it was concluded that changes in the mobility of heavy metals by the salts application were determinated through different dynamics of certain bases cations (particularly Ca²⁺ ) between soil solid and soil solution. The lower dynamics of Ca²⁺ ions, and consequently decreasing in heavy metals desorption by K₂SO₄ application was influenced through CaSCO₄-precipitation in soil solution.