تاثير مواد افزودني شيميايي بر قابليت دسترسي فلزات سنگين سرب ، كادميوم و روي در خاك

EFFECT OF CHEMICAL ADDITIVES ON THE AVAILABILITY OF HEAVY METALS (Pb, Cd, Zn) IN SOIL

BACKGROUND AND OBJECTIVE: Hazards of heavy metals on human health and cleaning up contaminated soils with heavy metals by microorganisms and plants are very important subject. This study was performed to evaluate the effect of additives on the availability of Pb, Cd and Zn in the soil of Amol industrial areas. METHODS: The soil after mixing by a concrete mixer was dried in the oven and then grounded and passed through polyethylene sieve with 2ʹ holes. The soil extraction was done by distilled water, Ca C12s KNO3, ammonium citrate and EDTA in 0.25, 0.5, 1, 2 and 4 molar and mixed by a shaker in 75 rpm for 10 hours. Finally, concentration of Zn, Pb and Cd as.tg/gr were measured by atomic absorption spectrometry. FINDINGS: In this study, concentration of Pb, Cd and Zn were 13510±124I pg/gr, 127±16.50pg/gr and 3000±1180pg/gr, respectively. It has been determined that the availability of Zn with different additives and with distilled water was more than the availability of Pb and Cd. Mean concentration of Pb by EDTA, ammonium citrate and potassium nitrate were 2110pg/gr, 1025 sg/gr and 195µg/gr, respectively. Mean concentrations of Cd by these additives were 83µg/gr, 71.tg/gr and 561ag/gr respectively and mean concentrations of Zn were 78941.1g/gr, 4982p.g/gr and 2744pg/gr. The best concentration of Zn and Cd was obtained by KNO3 in two molarity and by EDTA and ammonium citrate in 1 molarity. Furthermore, the best concentration of Pb was obtained by EDTA and ammonium citrate in one molarity and by KNO3 was obtained in more than one molarity. CONCLUSION: Using chemical additives such as EDTA and ammonium citrate are effective to increase availability of heavy metals.