Study of Remediation of Soil Contamined with Heavy Metals by Coal Fly Ash

The labile fraction of heavy metals in soils is the most important for toxicity for plants. Thus it is crucial to reduce this fraction in contamined soils to decrease the negative effect of heavy metals. In an experiment, the effects of two additives on the labile fractions of Cu, Mn and Zn were investigated in a soil contamined during long-term application. The additive used was the coal fly ash. The treated soil was further enriched with heavy metals and allowed to age at room temperature for 30 days. After this period, they were extracted plant-available (EDTA; HNO3; CH3COOH) metal species. The addition of fly ash strongly reduced the plant-available of Mn for plants but to a lesser extent this applies to the plant-available of Cu and Zn for plants. By addition of 1% of fly ash as well as 2% of fly ash, the labile fraction of Cu, Mn and Zn were lowered by 6.3, 145.0 and 29.7 mgkg, respectively. Moreover essential correlation between total Cu and Zn contents was stated in the soil with plant-available content of metals, with reference to both metals. Value of coefficients of correlation is attesting to it between the total and plant-available Cu and Zn contents which are respectively equal: R(Cu) = 0.845, R(Mn) = 0.864 and R(Zn) = 0.872 for p = 99.5%. The results suggested that leading into the soil of the additional amount of fly ash can be an effective way of chemical remediation with reference to soils contaminated by Cu or Mn or Zn. Because he causes immobilization of examined heavy metals in the soil and in the process in the arrangement a—soil is limiting the availability of these metals plant and more distant bonds of the food chain.