Mitigação do cádmio disponível usando calcário e gesso como corretivos em solo de textura franco arenosa

Abstract

Due to increasing concern about soil pollution and consequent Cd translocation to the food, the research for mitigation strategies is necessary. In this context, the objective of this study was to evaluate the soil Cd retention capacity through chemical extractors using sorghum as an indicator; to quantify the effect of the soil conditioners applied and to observe Cd behavior with various levels of soil bases saturation. The experiments were carried under greenhouse and laboratory conditions. Samples from an Argissolo (Brazilian soil classification system) were used. The first experiment under laboratory conditions used a dose of 30 mg.kg, three comparable levels of soil base saturation (natural, 80, 100%) and four treatments (without addition, limestone, 75% limestone + 25% gypsum, limestone 50% + 50% gypsum and 100% gypsum) being possible to quantify lower Cd concentrations as pH levels were increased due to changes in soil base saturation percentage and bigger limestone proportions with a reduction of 46,9%. In the greenhouse experiment three conditioners (without addition, limestone and limestone 75% + 25% gypsum) and 4 Cd doses (0, 5, 10, 20 mg.kg) were utilized. Fifty-five days after plants emergence, plants were collected to quantify the metals, Ca and Mg concentrations in plant ́s shoots and roots tissues, these concentrations were used to calculate Cd bioconcentration and translocation factors, demonstrating that sorghum plants did accumulate most of the Cd in the roots, showing >1 BCF values, indicating them as potentially accumulators. In soil, the pH level and relationship between the elements analyzed were the most determining factors in soil Cd availability which presented lower concentrations also with higher CaCO3 proportions.