Multi-elemental Analysis and Health Risk Assessment of Commercial Yerba Mate from Brazil.

Consumption of yerba mate occurs mostly in the form of hot infusion (chimarrão). Water solubility of elements found in commercialized yerba mate is needed to establish nutritional value and risks associated with potentially toxic elements. In this study, yerba mate products marketed in three Brazilian states (Paraná, Santa Catarina, and Rio Grande do Sul) for chimarrão were analyzed. Total (dry product) and hot water-soluble concentrations of Al, As, B, Ba, Ca, Cd, Co, Cs, Cu, Fe, K, Li, Mg, Mn, Mo, Ni, P, Pb, Rb, S, Se, Sr, Ti, V, and Zn were determined by inductively coupled plasma mass spectroscopy (ICP-MS). Total concentrations of the ten top elements followed the order of K>Ca>Mg>Mn>P>S>Al>Fe>Ba>Zn. The most soluble elements were B, Cs, Ni, Rb, and K, with values greater than 80%. The lowest water-soluble elements were V, Fe, and Ti (values <10%), followed by Ba, Cd, Al, As, Sr, Ca, and Pb with solubility between 10 and 20%. Although total Cd levels in yerba mate products were often above those permitted by South America legislation, estimated daily consumption intake indicated no risk associated with the chimarrão beverage. Manganese was the micronutrient with the highest total and soluble levels in yerba mate, which surpassed recommended daily intake values when considering a consumption amount of 50 g day-1 of yerba mate as chimarrão. The consumption of yerba mate is safe and contributes to intake of nutrients. The Cd and Pb reference values of yerba mate products sold in South America should be revised.

Hybrid technologies for remediation of highly Pb contaminated soil: sewage sludge application and phytoremediation.

Phytoremediation techniques and stabilization of heavy metals with municipal sewage sludge (SW) in soils are usually studied separately. We aimed to verify the potential of the combined use of phytoextraction method and metal stabilization with SW in the recovery of soil with high Pb content (total = 28,650 mg kg-1 and exchangeable = 1,120 mg kg-1) and to verify the effect of the association of these two techniques on the Pb fractions in the soil (stabilization). We have tested five doses of SW (0; 13.4; 26.7; 53.4; 106.8 Mg ha-1) and three cultivation conditions (uncultivated, black oats and forage turnip). The SW application in soil with a high Pb content favored the nutrition and growth of the plants (shoots and roots) and promoted an increase in the Pb absorption, a desirable combination in phytoextraction. The SW application and the cultivation of plants had a positive effect on the stabilization of Pb in the soil. It was verified decrease of the exchangeable fraction and increase precipitated and adsorbed by inner-sphere at the edges of the kaolinite and gibbsite. The combined use of SW and phytoremediation is very promising and should be tested on soils with moderate levels of heavy metals. Novelty statement: We believe that the study presents a more comprehensive methodology to assess and to recover soils highly contaminated with heavy metals. Conditions of the high toxicity of heavy metals in the soil compromise the growth of plants and limit the effectiveness of phytoremediation. We aimed to verify the potential of the combined use of phytoextraction and stabilization with sewage sludge in the recovery of soil with a high Pb content and to verify the effect of the association of these two techniques on the Pb fractions in the soil (stabilization). Often, the simple evaluation of the reduction in total Pb contents with phytoremediation is not sufficient to describe the magnitude of soil decontamination. The ideal is also to determine the different forms of Pb (such as: soluble; exchangeable; precipitate; complexed in organic matter; inner-sphere adsorption in Fe and Mn oxides; inner-sphere adsorption in gibbsite and kaolinite; residue) in soil before and after the recovery techniques to access the possible migration to more stable environmental Pb fractions.