The objective of this study was to determine the concentrations of heavy metals in bagged and leaf black teas of the same brand and evaluate the percentage transfer of metals to tea infusion to assess the consumer exposure. Ten leaf black teas and 10 bagged black teas of the same brand available in Poland were analyzed for Zn, Mn, Cd, Pb, Ni, Co, Cr, Al, and Fe concentrations both in dry material and their infusion. The bagged teas contained higher amounts of Pb, Mn, Fe, Ni, Al, and Cr compared with leaf teas of the same brand, whereas the infusions of bagged tea contained higher levels of Mn, Ni, Al, and Cr compared with leaf tea infusions. Generally, the most abundant trace metals in both types of tea were Al and Mn. There was a wide variation in percentage transfer of elements from the dry tea materials to the infusions. The solubility of Ni and Mn was the highest, whereas Fe was insoluble and only a small portion of this metal content may leach into infusion. With respect to the acceptable daily intake of metals, the infusions of both bagged and leaf teas analyzed were found to be safe for human consumption.
In the present study, sequential extraction of metals from bottom sediments, the risk assessment code and Phragmites australis bioaccumulation ability were used to assess ecological risk of trace metal pollution on aquatic ecosystems. Surface bottom sediments and leaves of reed collected from agricultural and urban areas were examined for Cu, Fe, Mn, Ni and Pb contents. Results showed that the total metal content in sediment cannot be regarded as a reliable indicator of metal pollution and the risk of environment. High total contents of the metals as well as contents in individual sediments fractions were connected with high organic carbon and domination of the silt-sand, clay-silt or clay particles. However, the percentage of metals bound to each fraction was independent from these properties of sediment. Particular metals characterized by different behavior in the sediments: Mn had the highest percentage bound to the most labile fractions; Cu and Ni had considerable high percentage in potentially bioavailable (reducible or oxidizable) fractions; Fe and Pb had high percentage in the residual fraction. The risk assessment code, sequential analysis and the bioindication method showed generally consistent results: no Cu, Fe and Pb pollution and a high risk of Mn pollution in the study sites, but each one gave different detailed information.
In the present study, the concentrations of trace and alkali metals in leaves of four common helophytes, Sparganium erectum, Glyceria maxima, Phalaris arundinacea, and Phragmites australis, as well as in corresponding water and bottom sediments were investigated to ascertain plant bioaccumulation ability. Results showed that Mn and Fe were the most abundant trace metals in all plant species, while Co and Pb contents were the lowest. Leaves of species studied differed significantly in respect of element concentrations. The highest concentrations of Mg, Na, Fe, Mn, Cu, Pb, and Ni were noted in S. erectum while the highest contents of Co, Ca, Zn, and Cr in Phalaris arundinacea. Phragmites australis contained the lowest amounts of most elements. Concentrations of Co, Cr, Fe, and Mn in all species studied and Ni in all except for Phragmites australis were higher than natural for hydrophytes. The leaves/sediment ratio was more than unity for all alkali metals as well as for Cu and Mn in Phragmites australis; Cr, Co, and Zn in Phalaris arundinacea; Cr and Mn in S. erectum; and Cr in G. maxima. High enrichment factors and high levels of toxic metals in the species studied indicated a special ability of these plants to absorb and store certain non-essential metals and, consequently, their potential for phytoremediation of contaminated aquatic ecosystems.
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