Metal accumulation and tolerance of selected plants of asbestos tailings (Stragari)

The aim of this study was to determine the concentrations of 11 metals in the soil of asbestos tailings in Stragari, Serbia, and in the selected plant species that grow on it, to determine the ability of the plant species in accumulation and tolerance of researched metals. Concentrations of elements researched in the soil had this order: Mg> Fe> Ca> Ni> Cr> Mn> Co> Zn> Pb> Cu> Cd. Concentrations of the metals in plants was variable, dependent on the plant species and types of metals, and graded in the order: Mg> Ca> Fe> Ni> Mn> Cr> Zn> Co> Pb> Cu> Cd. The concentrations of Ni and Cr in the investigated soil were above remediation values, as well as the maximum allowable concentration of substances in the soil according to regulation of Republic of Serbia, and the concentration of Cd and Co were above limit values for a given metals in the soil. The metal uptake does not necessarily correlate with metal content in the soil. Metal uptake by plants depends on the bioavailability of the metal in soils, which in turn depends on the retention time of the metal, as well as the interaction with other elements and substances. However, the most Mg, Fe, Mn, Pb, Cd, Co and Cr were found in species Sanguisorba minor, Ca and Cu in Eryngium serbicum, Ni in Alyssum murale, and Zn in Euphorbia cyparissias. In the Euphorbia cyparissias, it were determined the biological absorption coefficients greater than 1 for Zn and Cu, and in the species Eryngium serbicum and Sanguisorba minor greater than 2 for Cu. The results of this study emphasize the tolerance of several metal by species Sanguisorba minor, present the ability of Euphorbia cyparissias in accumulation of Zn and Cu, as well as of Eryngium serbicum and Sanguisorba minor in accumulation of Cu. Obtained results present the momentary picture of investigated locality, open a lot of questions connected with relationships soil/plant, contents of elements in both systems, their interactions and influences and represented the base for further research.

Strength Loss Method to Evaluate the Sulfate Attack Resistance of the Cement-Porous Silica Fume Mortar

The key factors for activity of asbestos tailings acid leaching residue (ATALR) and activated process were researched by the way of orthoplan, so as to make a new type of high-active mineral admixture in cement-based material, named as porous silica fume (PSF). Then with the strength loss indexes designed, the sulfate attack resistance of cement-PSF mortars was evaluated, which was dunked in solution of sodium sulfate during from 6 to 12 months. The results indicated that thermal activated temperature and holding time was the key factor for compressive strength, while holding time and grinding time for flexural strength. The optimal activated process was the thermal activated temperature at800°C needing to hold for 1 hour before grinding for 20minuteswhilethe appropriate amount of PSF was 5%~12% in cement mortar. When 5%~8% PSF contained, the sulfate attack resistance of cement mortar can be improved obviously, and the role was similar to silica fume (SF). PSF activated from ATALR is helpful for resource utilization of asbestos tailings, in order to improve ecological environment in the asbestos mine town and promote cement-based material development.