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In this study, we investigated if variations in the stable Tl isotope ratios in soil samples from different profiles can be linked to data on the extractability and speciation of soil Tl and whether the isotopic data allow drawing conclusions on the geochemical processes linked with soil formation/rock weathering. We observed a significant accumulation of the heavy 205Tl isotope in the B horizons, with ε205Tl values that were up to 7 higher than in the underlying bedrock. This 205Tl enrichment, however, was neither reflected in the speciation of Tl nor its chemical fractionation. Furthermore, exchangeable soil Tl in the B horizons was found to be much isotopically lighter than the bulk soil Tl. Our findings suggest that the observed isotopic shift may be linked to cyclic Tl mobilization and immobilization processes over the period of rock weathering and soil formation. Oxidative Tl uptake by Mn-oxides associated with a 205Tl enrichment, continuous weathering of the Tl(III)-containing phases, followed by a Tl(I) remobilization (leading to enrichment in 205Tl) are suggested to be responsible for the binding of the heavy Tl isotope fraction into other phases, mainly illite (a dominant Tl host), which is not normally expected. We therefore conclude that the use of the Tl isotopic data for phase or sorption mechanism identification in a dynamic multi-phase (soil) system can be very complicated, but, in contrast, suggesting their efficient use as a proxy for redox-controlled processes.

Forest soils near industrial zones can be endangered by acid deposition and by dust deposition containing potentially toxic elements (PTEs). Soils of the study area are acidified and the surface enrichment with Cd, Cu, Pb, and Zn reflects anthropogenic contamination. Two forms of all PTEs were evaluated: potentially mobilized (2M nitric acid extraction) and mobile (0.01M CaCl 2 extraction) -the most toxic form. Negligible amounts of Cu and Pb were found in the mobile form. Pb mobilization is decreased by co-emitted bases and Cu mobilization is mainly controlled by soil reaction. These elements represent just a potential risk for the ecosystem. The mobile forms of Cd, Zn, and Mn account for approximately 30% of potentially mobilized forms in organic horizons. These elements could pose a problem to ecosystem vitality. Cd is toxic at small concentration and its content in mobilized form approaches the critical load. Cd can be considered the most dangerous element in the study area. Zn concentration is not reaching the limit value. Mobilization of Zn and Pb is mainly controlled by Ca and Mg content. The highest concentrations of Mn were found in the mineral horizons. It predicates a geogenic origin. The lowest percentage of the mobile form is in mineral horizon and its mobilization is controlled mainly by pH. Based on these results, a direct damage of forest by PTE contamination in the Silesian Beskids can be excluded. Lower contamination level along with acid condition and P deficiency could act as a permanent stress factor. Stressed forest is more predisposed e.g. to frost or insect damage.

The recent rapid expansion of nanotechnologies has increased concern over the impact of engineered nanoparticles (ENPs) on the environment and biota. Although the toxicity of ENPs has received considerable attention in the recent years, there are still gaps in our knowledge of the mechanisms responsible for their effects. In this study, we tested the toxicity of various metal oxide ENPs (Al2O3, CuO, Fe3O4, MnO, TiO2, and ZnO), including nanowires together with their bulk counter particles and soluble metal salts, on germinating seeds of Sinapis alba L. Fe3O4, TiO2, MnO2, and Al2O3 ENPs did not negatively affected seed germination at any tested concentrations. However, CuO and ZnO ENPs showed a dose-dependent inhibition of germination. Metal ions were more toxic than metal oxide particles at corresponding concentrations. The highest toxicity was exhibited by Cu, followed by Zn, Fe, Al, and Mn ions. A comparison of ENPs with bulk materials did not reveal significantly higher ENP toxicity. Similarly, nanowires showed effects similar to other nanoparticles and bulk materials. Our results indicate that the nanosize or shape of particles did not play a crucial role, whereas metal ions released into cultivation media and accumulated in seedlings contributed significantly to the phytotoxicity of metal oxides.

The quantitative analysis of Al, B, Cu, Fe, Mn, P and Zn by inductively coupled plasma optical emission spectrometry (ICP-OES) and Ca, K and Mg by atomic absorption spectrometry (AAS) has been carried out in both the raw material and infusions from 31 samples of traditional plant stimulants (tea and coffee) and mate, rooibos, honeybush and chamomile. The results were discussed with respect to differences to the beverage quality and their role in the human diet. The levels of elements not significantly differ between tea types (black, green, oolong, white), and between Arabica and Robusta coffee. In comparison with tea, coffee was found to be a poor source of elements with the exception of Ca and Fe. High levels of B, Ca, Cu, Mn, Mg and Zn were found in mate (mainly green type) and of B, Ca, Cu, Fe and P in chamomile, whereas the amounts of all elements in rooibos and honeybush infusions were low (except of Ca). Apart from tea, other stimulants appeared to not represent important sources of potentially harmful amounts of Al for the human diet.

Soil acidification promotes Al release from minerals and parent bedrocks; it also affects Al mobilization and speciation. Speciation of KCl extractable and water-extractable Al in forest soils was done by means of HPLC/IC method. Species Al 3+ were the most abundant Al forms in the KCl extracts (around 93%). Prevailing Al forms (more than 70%) in aqueous extracts were Al(X) 1+ , {i.e., Al ( OH ) 2 + , Al ( SO 4 ) + , AlF 2 + , Al(oxalate) + , Al(H-citrate) + , etc.} species. It is assumed that most of KCl and water-extractable Al is bound in soil sorption complex (i.e., highly dispersed colloidal fraction of the soil solid phase creating negative charge) where majority of Al exists in the form of Al 3+ species. The ECEC values, total carbon content and parameters related to soil organic matter composition (N and S content) have apparent effect on Al speciation. The most toxic Al 3+ species are more concentrated in the B horizons compared to the A and E horizons. Aqueous extracts simulate Al release to soil solution under normal conditions; it can thus exhibit the actual Al toxicity. On the other hand, KCl extraction describes a potential threat for case of strong disturbance of natural soil conditions.

Labile Al forms and species can be a threat in acid soils due to their potential toxicity to plants. However, there is no universally accepted extraction method. Several extraction reagents for Al release from soil have been tested. KCl (0.5 or 1 M) is recommended for extraction of exchangeable Al, while 0.5 or 0.3 M CuCl(2) is suggested for extraction of 'weakly organically bound Al'. Both 0.1 and 0.05 M Na(4)P(2)O(7) are shown to be suitable for the extraction of 'total organically bound Al'. These extractions are relatively simple, robust, and applicable to different soils and soil horizons. In the second part of the paper, detailed speciation of exchangeable soil Al by means of an HPLC instrument equipped with an ion column (IC) is presented. An experimental set-up is described and tested on a set of samples. Interpretation of the speciation results is proposed, based on the separation of Al ions and Al complexes according to their charge. Speciation is shown to be dependent mainly on soil pH and organic matter quality. A general scheme of Al fractionation and speciation in soil is proposed.

In order to determine the mobility of Pb, Zn and Cd in soils from the Přibram region (Czech Republic) heavily contaminated by metallurgy, two profiles of alluvial soils were closely studied. Total contents of heavy metals were determined a�er digestion with a mixture of HF and HClO4. Heavy metal mobility was assessed using the mobility factor (MF) that represents the proportion of heavy metals present in the exchangeable and carbonate bound fraction based on the Tessier’s sequential extraction procedure. The MF ranged from 2 to 46% for lead, 19 to 62% for zinc and 61 to 94% for cadmium. The profile distribution of zinc and cadmium showed a variable development with depth, which is caused by high amounts of these metals present in labile forms. The profile distribution of lead (the least mobile metal) is characterized by a gradual decrease with depth. The results indicate a higher contamination of the soil profile situated 2.5 km away from the smelter in comparison with the profile in its close vicinity. This fact confirms the existence of extreme fluvial contamination.