V. Ya. Kavun

Metal accumulation in mussels of the Kuril Islands, north-west Pacific Ocean

Concentrations of cadmium, copper, iron, lead, manganese, nickel and zinc were investigated in two species of mussel from the Kuril Islands in the north-western Pacific Ocean: the short-lived mussel Mytilus trossulus and the much larger and longer-lived Crenomytilus grayanus. The concentrations of most elements were low, and these reported levels are believed to reflect background values for pristine locations. However, both iron and zinc concentrations were elevated in some samples taken from areas of hydrothermal vent activity, and these are believed to reflect the enrichment of the two metals in solution at such sites. Furthermore, the concentrations of cadmium were unusually elevated in both species of mussel, especially in the longer-lived C. grayanus. The high accumulation of cadmium in mussels from the Kuril Islands is believed to reflect regional upwelling, but it is also postulated that filtration rates of the mussels are high due to low levels of suspended matter, and this leads to a high assimilation efficiency for cadmium. The distribution of cadmium amongst the tissues of C. grayanus is also reported, and the need for further ecotoxicological studies in the area is proposed.

The Effect of Metal Concentration in Bottom Sediments on the Accumulation of Metals by the Mytilids Crenomytilus grayanus and Modiolus kurilensis

The relationship between the concentration of Pb, Cu, Cd, Zn, and Ag in soft tissues of mytilids Crenomytilus grayanus and Modiolus kurilensis and in bottom deposits was studied to determine the potential and limitations in the use of these molluscs as bioindicators of contamination of coastal waters near Vladivostok (northwest of the Sea of Japan). It was found that the mussel C. grayanus began to accumulate Pb and Cu after certain threshold concentrations of these metals (60 and 150 μg/g respectively) in fine fractions of sediments was reached. Accumulation of Pb and Cu by M. kurilensis also depended on the level of sediment contamination, but the higher initial metal content in tissues and the higher individual variability reduced the sensitivity of this species as a bioindicator. Accumulation of Cd and especially of Zn in mytilid tissues is adjusted by the organism, which restricts the opportunity of their use for tracking the anthropogenic input of bioavailable forms of these metals.

Ion mobility and transport in β-PbF2 doped with alkaline-earth fluorides

We have studied ion mobility and conduction in (1 − x)PbF2 · xMF2 (M = Mg2+, Ca2+, Sr2+, Ba2+; 0.05≤x≤0.1) solid solutions by 19F and 207Pb NMR and impedance spectroscopy. The results are used to analyze the factors governing the structure of the fluoride sublattice and the nature and energetics of ionic motion in the temperature range 170–550 K. The solid solutions are shown to have high ionic conductivity (∼10−4 to 10−3 S/cm at temperatures above 470 K, with activation energies Ea ≤ 0.3−0.6 eV) and are, therefore, potentially attractive for engineering materials with tailored electrical properties.

Heavy Metal Accumulation and Distribution in Organs of the Mussel Crenomytilus grayanus from Upwelling Areas of the Sea of Okhotsk and the Sea of Japan

The subcellular and cytosolic distribution of Zn, Fe, Ni, Cu, Mn, Cd, and Pb in the digestive gland and kidney of the mussel Crenomytilus grayanus from upwelling areas of the Sea of Okhotsk and the Sea of Japan was studied. Cd, Zn, Pb, and Ni have accumulated in the kidneys of mussels from these areas. When the concentrations of both essential and toxic metals in the mussel organs had increased significantly, their redistribution into the cytosol took place. Gel chromatography of cytosolic proteins in the kidneys of mussels sampled in the area with a strong stationary upwelling revealed metallothioneins. This is uncommon for bivalve mollusks from unpolluted areas. High molecular weight proteins act as preliminary ligands for Cd.

Ionic mobility and electrical transport in 45ZrF4 · 35BiF3 · 20MF (M - Li, Na, K) glasses studied by NMR and impedance spectroscopy

The ionic mobility and electrical transport in 45ZrF4 · 35BiF3 · 20MF (M - Li, Na, K) glasses have been studied by 7Li, 19F, and 23Na NMR and impedance spectroscopy at temperatures from 200 to 500 K. In the range 400–440 K, the main kinds of ionic mobility in these glasses are local motions of fluorine-containing groups and lithium ion diffusion. The temperature range where the dominant kind of ion motion in the glasses is fluoride ion diffusion depends on the nature of the M+ cation. Above 470 K, the glasses offer rather high ionic conductivity: σ ≥ 10−5 S/cm.

19F and203,205Tl NMR and structural transformations in chain ammonium and thallium hexafluorozirconates and hexafluorohafnates

Unusual structural transformations were observed in ammonium and thallium hexafluorozirconates and hexafluorohafnates at 300–420 K using high-resolution NMR for solids. It was established that at 300–350 K the initial chain structure of these compounds of orthorhombic symmetry undergoes a transition to disordered state, and at higher temperatures it is transformed into an ordered uniaxial structure which is similar to that of trigonal Cs2ZrF6 and Cs2HfF6.

Internal mobility, phase transitions, and ionic conductivity in (NH4)6KZr4F23 and (NH4)6KHf4F23

The ion mobility, phase transitions (PTs), and conductivity in (NH4)6KZr4F23 (I) and (NH4)6KHf4F23 (II) have been studied by 1H and 19F NMR, DSC, and impedance spectroscopy. Types of ion motion in the fluorides and ammonium sublattices have been determined in the temperature range 150–480 K, and their activation energies have been evaluated. Compounds I and II undergo phase transitions in the temperature ranges 400–440 and 419–440 K, respectively, to form high-temperature modifications. The high ionic conductivity in (NH4)6KZr4F23 and (NH4)6KHf4F23 (>10−3 S/cm at 473 K) makes it possible to classify these compounds with superionic conductors.

Changes in the Microelement Composition in Organs and Tissues of the Bivalve Crenomytilus grayanus Acclimatized in a Biotope with Long-Term Heavy Metal Contamination

This paper deals with changes in the Fe, Zn, Cu, Cd, Mn, Pb, and Ni concentration in the muscle, gonad, mantle, gills, digestive gland, and kidneys of Gray mussels transplanted from two sites differing in the extent of metal contamination to a biotope with the impact from anthropogenic conditions in the course of their acclimatization. The rate of metal accumulation depended on the initial element concentration in the mussel organs. An abrupt change in the metal concentration in the environment was followed by a disturbance in the microelement balance in some organs. The microelement metabolism was shown to depend on mussel preadaptation to a changeable environment.

Heavy Metals in Organs and Tissues of the European Black Vulture (Aegypius monachus): Dependence on Living Conditions

The distribution of Fe, Zn, Cu, Cd, Mn, Pb, and Ni in the organs and tissues (kidneys, liver, lungs, brain, heart, muscles, and feathers) of the European black vulture (Aegypius monachus) was studied. It was shown that heavy metals were not responsible for the mass mortality of these birds in southern Primorye in the winter of 2001–2002. The level of pollution with heavy metals of the range of European black vultures wintering in this region (northern China and western Mongolia) may be regarded as insignificant.

Ion Mobility and Electrophysical Properties of Potassium Hexafluorozirconate K2ZrF6

In our 19F NMR and impedance spectroscopy study, we investigated the mobility of fluoride ions (270-550 K) in polycrystalline K2ZrF6. A structural phase transition was found for K2ZrF6 in the temperature range of ∼513 to 518 K. The high-temperature β-K2ZrF6 modification is characterized by translational diffusion of the fluoride ions and uniaxial anisotropy of the 19F nuclear magnetic screening tensor. The electrophysical characteristics of K2ZrF6 were investigated in the temperature range of 300 to 560 K. It is established that the β-K2ZrF6 phase is characterized by high ionic (superionic) conductivity above 540 K (Σ ∼ 3.2× 10-4 S/cm, T=560 K).