Heavy Metals in the Bottom Sediments of the Black Sea Northwestern Shelf in Recent Years

Purpose. The study is aimed at investigating metal accumulation in the 0–2 cm layer of the bottom sediments of the Black Sea northwestern shelf over 2000–2020, and at identifying the sea bottom areas subjected to the increased anthropogenic load through comprehensive assessment of the degree of their pollution taking into account their granulometric composition. Methods and Results. The bottom sediments were sampled annually from the 0–2 cm depth at the same stations. The detected metal concentrations were compared with their content in the Earth crust and the background values. The dynamics and trends of the individual metals’ content in the shelf bottom sediments were assessed for the whole period of observations. The notion of the average characteristic concentration of an element is introduced; the procedure for its calculation is represented. The pollution of bottom sediments was analyzed with the regard for the element average characteristic concentration in the bottom sediments of various granulometric types. Increase in the average content of lead, zinc and chromium was revealed from the beginning of the observation period to 2020. The seasonal dynamics of these elements was found in the whole water area under study (as well as the iron content at some areas). Conclusions. Multiple cases of the lead, manganese and chrome concentrations exceeding their content in the Earth crust were recorded; as for zinc and copper, such cases were few and sporadic. The tendencies in variation of the bottom sediments content were determined: the average long-term values of the lead concentration increased by 1.2 times, those of zinc – by 1.6 times, and those of chrome – by 2 times; the concentrations of iron, manganese and copper remained essentially the same. Seasonal dynamics of the zinc, chromium, lead and iron content was shown. For a number of metals, the cases when their absolute content exceeded their average characteristic concentration in the corresponding type of the bottom sediments had been found. The regions subjected to a multi-faceted anthropogenic load were identified; the areas of possible local inflow of the monitored elements were revealed. The bottom sediments sampled in 2019 were the most polluted.

Earth's balanced climates in view of their energy budgets

Earth’s well-known energy budget scheme is subjected to variations representing changes of insolation and atmospheric absorption. The Charney Report variability cases of doubled atmospheric CO2 concentration and insolation increase by 2 % are found reproducible. The planetary emissivity is revealed linear to surface temperature, conformant with measurements. Atmospheric water vapor with its characteristic concentration-temperature dependency appears as a major component in Earth’s energy balancing mechanisms. From this, shift towards fewer and stronger rainfall events is prescribed for rising temperatures.

Drivers of cloud droplet number variability in the summertime in the southeastern United States

Here we analyze regional-scale data collected on board the NOAA WP-3D aircraft during the 2013 Southeast Nexus (SENEX) campaign to study the aerosol–cloud droplet link and quantify the sensitivity of droplet number to aerosol number, chemical composition, and vertical velocity. For this, the observed aerosol size distributions, chemical composition, and vertical-velocity distribution are introduced into a state-of-the-art cloud droplet parameterization to show that cloud maximum supersaturations in the region range from 0.02 % to 0.52 %, with an average of 0.14±0.05 %. Based on these low values of supersaturation, the majority of activated droplets correspond to particles with a dry diameter of 90 nm and above. An important finding is that the standard deviation of the vertical velocity (σw) exhibits considerable diurnal variability (ranging from 0.16 m s−1 during nighttime to over 1.2 m s−1 during day), and it tends to covary with total aerosol number (Na). This σw–Na covariance amplifies the predicted response in cloud droplet number (Nd) to Na increases by 3 to 5 times compared to expectations based on Na changes alone. This amplified response is important given that droplet formation is often velocity-limited and therefore should normally be insensitive to aerosol changes. We also find that Nd cannot exceed a characteristic concentration that depends solely on σw. Correct consideration of σw and its covariance with time and Na is important for fully understanding aerosol–cloud interactions and the magnitude of the aerosol indirect effect. Given that model assessments of aerosol–cloud–climate interactions do not routinely evaluate for overall turbulence or its covariance with other parameters, datasets and analyses such as the one presented here are of the highest priority to address unresolved sources of hydrometeor variability, bias, and the response of droplet number to aerosol perturbations.

Adsorption Behavior of Sodium Hydrogen Sulfate on Silica Gel

The adsorption behavior of sodium bisulfate on silica gel was studied. The adsorption isothem of sodium hydrogen sulfate on silica gel were measured in the temperature range of 298.15 ~ 328.15 K, and the Langmuir model and the Dubini-Radushkevich (D-R) model were used to fit the experimental isotherm data. The average characteristic concentration (Ce') of NaHSO4 was determined at different temperatures to distinguish chemisorption from physisorption. The values of the mean free energy (E) calculated from the D−R isotherm equation indicated that the adsorption of NaHSO4 on silica gel occurs by sequential chemical and physical mechanisms.

Comparative Study of Element Composition of Species of the Genus Dasiphora (Rosaceae) in the Primorsky Region and Republic of Buryatia

Element composition was determined in the aboveground organs (leaves and stems) of plants of four species of the genus Dasiphora: D. fruticosa, D. parvifolia, D. mandshurica, D. gorovoii grown in the Primorsky Territory and Republic of Buryatia. The results were compared with two taxa (D. davurica and the variety D. davurica var. flava) which had been studied earlier. Content of 21 elements in the aboveground organs and samples of soil from sites of the plant collection was analysed by the method of X-ray fluorescence analysis using synchrotron radiation (SRXRF). For the first time, composition and content of the elements were determined for a new taxon D. gorovoii. The highest total content of the macroelements (K, Ca) was found in the aboveground organs of the two taxa: D. davurica and D. davurica var. flava; the highest content of the microelements was determined in the aboveground organs of D. gorovoii, D. mandshurica, and D. fruticosa. We found that each species had a characteristic concentration of elements.

Some problems connected with boron determination by atomic absorption spectroscopy and the sensitivity improvement

Two atomizers were compared: an N2O-C2H2 flame and a stabilized U-shaped DC arc with aerosol supply. Both the high plasma temperature and the reducing atmosphere obtained by acetylene addition to the argon stream substantially increase the sensitivity of boron determination by atomic absorption spectroscopy (AAS) when the arc atomizer is used. The results were compared with those for silicon as a control element. The experimental characteristic concentrations for both elements were compared with the computed values. The experimentally obtained characteristic concentration for boron when using the arc atomizer was in better agreement with the calculated value. It was estimated that the influence of stable monoxide formation on the sensitivity for both elements was about the same, but reduction of analyte and formation of non-volatile carbide particles was more important for boron, which is the main reason for the low sensitivity of boron determination using a flame atomizer. The use of an arc atomizer suppresses this interference and significantly improves the sensitivity of the determination.

Responses of diverse heterotrophic bacteria to elevated copper concentrations

The influence of copper on the growth of Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, Bacillus subtilis, Vibrio parahaemolyticus, Vibrio alginolyticus (three strains), and an unidentified Vibrio sp. was examined in batch cultures. The effects of copper at micromolar concentrations varied from undetectable to complete growth inhibition. Each strain was able to recover from a growth lag observed after copper addition at a characteristic concentration. Copper concentrations that allowed recovery ranged from 25 to 150 μM. Extracellular proteins in the medium of cultures that had recovered from copper stress were compared with those from control cultures. Protein profiles were analyzed for the presence of proteins similar to extracellular copper-binding proteins (CuBP) previously reported in V. alginolyticus. CuBP-like proteins were found in each Vibrio sp. examined. A protein of similar molecular mass was also detected in copper-stressed cultures of P. aeruginosa and not in control cultures. Escherichia coli and Bacillus spp. did not produce CuBP-like proteins. The data show that CuBP-like proteins are not produced by all bacteria in response to copper stress and indicate that such proteins are common in marine Vibrio spp.Key words: copper toxicity, heterotrophic bacteria, extracellular protein.

Responses of the early chick embryo to external cAMP sources

Early chick embryos were stimulated with local sources of cAMP. Three major effects were observed: bending of the embryonic axis, attraction of cells on the ventral surface of the embryo, and disruption of the blastodisc. Each had a characteristic concentration dependence. These results are compared with those from studies of cells disaggregated from similar embryos.

THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR

The technique of Abrams and Sollner for the preparation of electropositive dried protamine collodion membranes has been improved. Porous collodion membranes cast on the outside of rotating tubes are treated for 48 hours with a solution of 2 per cent protamine sulfate buffered at pH 11. After being washed thoroughly the membranes are dried in air for several hours, soaked in water for several hours, and removed from the tubes. Further drying in air but without support shrinks the membranes slightly. The resulting membranes are designated "permselective" or "megapermselective" protamine collodion membranes. These membranes regularly give characteristic concentration potentials of –52 to –53 mv. and (in 0.1 M KCl) resistance of 0.5 to 15 ohms per membrane of 50 cm.2 area. This resistance is several orders of magnitude smaller than that of the conventional dyestuff- and alkaloid-impregnated positive membranes. The megapermselective protamine collodion membranes can be kept either dry or in water for prolonged periods without detectable deterioration. They are quite smooth, have a regular shape, and stand considerable handling without breakage. The megapermselective protamine collodion membranes are the electropositive analogues of the electronegative megapermselective collodion membranes described by Carr and Sollner.

THE STRUCTURE OF THE COLLODION MEMBRANE AND ITS ELECTRICAL BEHAVIOR

1. Experiments were carried out to decide whether or not the electromotive properties of dried collodion membranes depend upon their thickness. 2. A number of dried collodion membranes of varying thickness, 3–160 µ, were prepared from collodion preparations of different electrochemical activity. The characteristic concentration potentials across them were measured and the means of these values determined for each thickness. 3. The characteristic concentration potentials across dried collodion membranes are a function of their thickness. The thinnest membranes yield in all cases the lowest concentration potentials; increasingly thicker membranes give increasingly higher potential values, until a constant value is reached which is characteristic of the particular collodion preparation used. With electrochemically active collodion, characteristic concentration potentials approaching the thermodynamically possible maximum are obtained with membranes of only 10 µ thickness, thinner membranes giving appreciably lower values. With two rather inactive commercial collodion preparations the characteristic concentration potential increases from about 30 mv. for membranes 3 µ thick to about 42 mv. for 20 µ membranes; still thicker membranes do not show a significant increase in the potential values. With a highly purified collodion preparation the constant maximum value was found to be about 32 mv., 4 µ thick membranes giving only about 22 mv. 4. These results do not support the homogeneous phase theory as applied to the dried collodion membrane. They are readily compatible with the micellar-structural theory. Several special possible cases of the latter as applied to the dried collodion membrane are discussed.