Heavy metal exposure affect plant productivity by interfering, directly and indirectly, with photosynthetic reactions. The toxic effect of heavy metals on photosynthetic reactions has been reported in wide-ranging studies, however there is paucity of data in the literature concerning thallium (Tl) toxicity. Thallium is ubiquitous natural trace element and is considered the most toxic of heavy metals; however, some plant species, such as white mustard (Sinapis alba L.) are able to accumulate thallium at very high concentrations. In this study we identified the main sites of the photosynthetic process inhibited either directly or indirectly by thallium, and elucidated possible detoxification mechanisms in S. alba. We studied the toxicity of thallium in white mustard (S. alba) growing plants and demonstrated that tolerance of plants to thallium (the root test) decreased with the increasing Tl(I) ions concentration in culture media. The root growth of plants exposed to Tl at 100 μg L−1 for 4 weeks was similar to that in control plants, while in plants grown with Tl at 1,000 μg L−1 root growth was strongly inhibited. In leaves, toxic effect became gradually visible in response to increasing concentration of Tl (100 − 1,000 μg L−1) with discoloration spreading around main vascular bundles of the leaf blade; whereas leaf margins remained green. Subsequent structural analyses using chlorophyll fluorescence, microscopy, and pigment and protein analysis have revealed different effects of varying Tl concentrations on leaf tissue. At lower concentration partial rearrangement of the photosynthetic complexes was observed without significant changes in the chloroplast structure and the pigment and protein levels. At higher concentrations, the decrease of PSI and PSII quantum yields and massive oxidation of pigments was observed in discolored leaf areas, which contained high amount of Tl. Substantial decline of the photosystem core proteins and disorder of the photosynthetic complexes were responsible for disappearance of the chloroplast grana. Based on the presented results we postulate two phases of thallium toxicity on photosynthesis: the non-destructive phase at early stages of toxicant accumulation and the destructive phase that is restricted to the discolored leaf areas containing high toxicant content. There was no distinct border between the two phases of thallium toxicity in leaves and the degree of toxicity was proportional to the migration rate of the toxicant outside the vascular bundles. The three-fold (nearly linear) increase of Tl(I) concentration was observed in damaged tissue and the damage appears to be associated with the presence of the oxidized form of thallium − Tl(III).

Alumina (Al₂O₃) with an average particle size of 63 μm was modified with the anionic surfactant sodium dodecyl sulfate (SDS) and then applied to (i) solid phase extraction and separation of both thallium(I) and thallium(III), and (ii) preconcentration of Tl(III) from waste water samples. Only Tl(III), in the form of its complex with diethylenetriaminepentaacetate (DTPA), was retained on the sorbent, from where it can be eluted with 40 % nitric acid. Thallium species were then quantified by ICP MS. The method was characterized by a LOD of 25 pg of Tl(I) and 160 pg of Tl(III) in 10 mL samples. A large excesses of Tl(I) over Tl(III) was tolerated, and relatively high levels of other metal ions, such as a 500-fold excess of Pb(II) and Cd(II), and a 2000-fold excess of Zn(II), respectively, do not interfere. The sorbent was easily prepared and possesses a high loading capacity, and these properties make it an attractive material for rapid and efficient extraction and speciation of Tl.

The inspiration for this study was the anxiety of Warsaw beekeepers, who raised the question whether location of hives in large urban agglomerations results in changes in concentrations of xenobiotics, toxic elements, and micronutrients in honey bees. Preliminary studies required elaboration of the research methodology, as the studied object is characterized by a low degree of homogeneity and the method of sample preparation affects obtained results. From many tested approaches, the use of washed and milled abdomens of the bees is recommended. Results obtained for such prepared samples are slightly lower than for whole bees, but their repeatability is higher, which enables easier interpretation of the trends and comparison of different locations. The contents of selected elements (As, Al, Cd, Co, Cr, Cu, Mn, Pb, and Zn) were compared in bees from urban and rural areas. The studies were supported by pesticides analysis. Also, it was checked whether these substances are accumulated on the surface or inside the bee’s body. The research indicates the markers of contamination: Al, As, and Cr on the surface and Cd inside the bodies of honey bees. The location of the hives does not influence significantly the content of “toxic,” nutrient metals and metalloids in bees (slightly higher levels of As, Al, Pb, and Cd were found in bees from urban areas). In terms of exposure to these elements and pesticides, the large city environment is not harmful for honey bees.