Heavy metal content in soil-like fractions on the landfills within Volgograd boundaries and assessment of health risk connected to its presence in the environment.

The heavy metal content (Cu, Ni, Pb, Zn, and Cd) in a soil-like fraction from two landfills located within the boundaries of Volgograd was described using pollution indices and health risks. The calculated pollution index (PI) values have shown a lack of Pb and Zn pollution in the soil-like fraction from both landfills. For landfill No.1, the pollution level was determined as very high for Cd and as low for Cu and Ni, and for landfill No.2, this level was determined as very high, low, and non-polluted, respectively. The Nemerov integral pollution index (NIPI) values (25.24-43.90 for landfill No. 1 and 10.37-40.38 for landfill No. 2) indicated a high level of pollution in a soil-like fraction with studied elements in both landfills. According to the calculated values of the hazard index (HI), which are significantly lower than 1 in all samples, there is no non-carcinogenic risk for children and adults associated with the presence of a soil-like fraction in the environment. The total potential carcinogenic risks (TCR) associated with the heavy metals in a soil-like fraction were determined to be high for both target groups. The health of a child target group (TCR = 1.30E-03 and 4.87E-04) was found to be more exposed to carcinogenic risk than an adult target group (TCR = 1.40E-04 and 5.21E-05). Because the risk of a carcinogenic effect is high, the use of a soil-like fraction from both landfills for territory reclamation without prior detoxification is not allowed.

Melanin formation in barley grain occurs within plastids of pericarp and husk cells.

Melanins are a class of darkly pigmented biopolymers which are widely distributed among living organisms. The molecular and cellular mechanisms adopted by bacteria, fungi and animals to synthesize melanin, have been well described, but less is known regarding their production in plants. Here, a pair of barley near isogenic lines, bred to differ with respect to the pigmentation of the spike, was compared in order to understand the tissue and cellular location of melanin deposition. The melanic nature of the pigments purified from black spikes was confirmed by a series of solubility tests and Fourier transform infrared spectroscopy. An analysis of grains harvested at various stages of their development revealed that intracellular pigmented structures first appeared in the pericarp and the husk of black spike plants at early dough stage. The co-localization of these structures with red autofluorescence suggested that they form in chloroplast-derived plastids, here designated "melanoplasts". Differences in dynamics of plastid internal structure during grain ripening were detected between the lines by transmission electron microscopy. Both lines accumulated plastoglobuli inside plastids, which persisted in black grain pericarp tissue up to the hard dough stage, while neither plastoglobuli nor any plastids were observed in grain of the control line at this stage. The role of plastoglobuli in melanin synthesis is discussed.