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The analysis of phytoplankton in the winter-spring period is important for investigating peculiarities of its annual dynamics and the Black Sea ecosystem overall functioning. Phytoplankton state in the winter-spring period in the Black Sea shelf zone is less studied than that of the summer-autumn season; conducting such a research is especially important for solving several problems, related to the productivity of the last links of the food chain, the formation of water hydrochemical regime, and the carbon cycle in the sea. The aim of the work is to assess the effect of seasonal conditions on the development of phytoplankton and its production estimates in the winter-spring period in the coastal waters of Crimea. The article presents the results of studies of hydrophysical (water temperature, density, and relative transparency) and biological indicators (chlorophyll a concentration, its fluorescence, taxonomic composition, and phytoplankton production estimates) in the Black Sea shelf zone in January – April 2016–2019. The studies were carried out at 50 stations, located in the coastal waters of Crimea from the Karkinitsky Bay to the Kerch Strait. Chlorophyll a concentration was measured by the standard fluorometric method, species composition was determined by microscopy, and phytoplankton specific growth rate was calculated according to the previously developed model. In winter (January – February), the values of chlorophyll a content and upper mixed layer depth were the highest (0.42–0.52 mg·m−3 and 44–58 m, respectively); in spring (March – April) they were 2–3 times lower. In January – February, the coccolithophore species Emiliania huxleyi (Lohmann) W. W. Hay & H. P. Mohler, 1967 predominated; in March – April, in different years, either dinoflagellates and diatoms or coccolithophores, dinoflagellates, and diatoms prevailed. In winter, chlorophyll a vertical distribution at most stations was uniform; in spring, unimodal profiles with a depth maximum prevailed, the location of which was not related to temperature and density gradients. Relative changes in chlorophyll a concentration and fluorescence with depth were usually the same. Phytoplankton production and daily production/biomass ratio (P/B) increased from winter to spring. There was no correlation between the values of integral production, biomass, and maximum specific growth rate of algae. Maximum specific growth rate was the least variable indicator. During the winter-spring period, algae in the photosynthetic zone divided on average once every 2–5 days.

According to experimental data for two spеcies of diatoms Phaeodactylum tricornutum and Skeletonema costatum, a mathematical description of the combined effect of light and temperature on the change in the intracellular ratio of organic carbon to chlorophyll a was carried out. The equation allows estimating the relative content of chlorophyll in algae in a wide range of temperature and light conditions. According to the results of calculations, the power relationship between temperature and organic carbon and chlorophyll was determined. The highest values of the relative content of chlorophyll were observed at high light intensity and low temperature, the minimum ones were at high temperature and low light intensity. At high density of the light flux, the effect of temperature on the specific content of chlorophyll in algae is more pronounced than at low irradiance.

The rovibrational levels for truly bound states were calculated for a weakly interacting dimer comprising an atom and a diatomic molecule. The off-diagonal Coriolis corrections were evaluated with perturbation theory. For the Ar - HCl dimer as a concrete example, the obtained results are compared with those from computer code BOUND [J. M. Hutson and C. R. Le Sueur. Comput. Phys. Commun., 241, 1–8, (2019)].

We report the results of experimental study for the N2 absorption in the millimeter wavelength range at pressure and temperature ranging, respectively, from 750 to 1500 Torr and from 265 to 310 K. The obtained data are shown to be in a good agreement with the previously published experimental results, as well as with the predictions issued from available empirical models of nonresonant absorption and from the simulation of the N2–N2 rototranslational collision-induced absorption performed recently using the classical trajectories method relying on complete ab initio potential and induced dipole surfaces. Analysis of the first spectral moments leads to a conclusion that the role of true bound (N2)2 dimer absorption is negligible at least in the range of atmospheric temperatures. New experimental data reported in this paper are supported by our theoretical modelling being however somewhat in excess of the data presented in the HITRAN/CIA database for the same spectral range. We consider our data as an update of the previously available so-called “dry” atmospheric continuum which is conventionally employed nowadays in the mm-waves propagation models.

The steady rise in energy demand is expected to continue in Singapore due to the country's economic and population growth. According to projections, electricity generation will increase by some 30% from 2010 to 2025. Despite the rise in demand, Singapore authorities have announced a commitment to reduce carbon emissions by 7-11% below 2020 business-as-usual levels, with a half of reductions coming from the power generation sector. In this study, we examine the average carbon dioxide (CO 2 ) emissions or grid factor of power generation in Singapore, and aim to assess the carbon emissions reduction potential arising from different fuel and generation technology mixes. Adding alternative feedstocks and/or displacing existing generation technologies can have a wide range of consequences on the theoretical grid factor. We show that emissions savings can vary substantially depending on the type of fuel sources that are either added to the mix, or used to displace existing generation feedstocks. The results highlighted in this study provide a Singapore-specific example for targeting medium to longer-term emission savings from the power generation sector.

The organic matter content in the eggs and early larvae of the ctenophores Mnemiopsis leidyi and Beroe ovata from the Black Sea was determined using the adapted microtechnique of dichromate oxidation. The content of organic matter in the eggs of M. leidyi (0.25 μg/indiv.) was 5 times less than in B. ovata (1.28 ± 0.29 μg/indiv.). The somatic content of organic matter was 0.25 ± 0.09 μg/indiv. (25.1 ± 8.3 μg/mg, wet wt) for 2-day-old larvae of M. leidyi (0.2–0.3 mm in body length) and 1.37 ± 0.19 μg/indiv. (67.1 ± 5.7 μg/mg wet wt) for larvae of B. ovata (0.4 mm in body length). The specific organic content of larvae of both species steadily decreased with an increase in ctenophore body size and weight, approaching 3–4 μg/mg of wet weight for 2 mm specimens of M. leidyi and 3–5 μg/mg of wet weight for 6 mm B. ovata. The specific organic content of early larvae was 20–30 times higher than that of adult ctenophores. The results of this investigation could be useful in the evaluation of the energy budget for somatic growth and generative production in these species. Calculations indicate that with specific wet weight growth rates of 0.43/day for M. leidyi larvae and 0.29/day for B. ovata larvae, their true organic increases are respectively 30 and 38% less, i.e., no more than 0.31/day for the former and 0.18/day for the latter species.

Data from over 40 yr (1950-1992) of expeditions to the Atlantic Ocean are summarised in the form of macroscale contour maps between 40°N and 40°S. The chl a concentrations from the sur- face and mesozooplankton in the upper layer (0 to 100 m) were analysed from 3992 casts and 1124 hauls respectively. General agreement between chlorophyll concentrations and mesozooplank- ton biomass distributions was noted on an ocean basin scale. There were non-linear relationships be- tween mean chlorophyll concentration within the 0 to 10 m layer and mesozooplankton biomass within the 0 to 100 m layer for summed data between December to May and June to November. A comparison of the total biomass of mesozooplankton und phytoplankton, in carbon units, indicated that this ratio varied from 0.15 to 1 in the 0 to 100 m layer and, on average, the phytoplankton biomass exceeded twice that of mesozooplankton. The seasonal cycles of phyto- and zooplankton biomass for 6 provinces of the tropical zone were qualitatively comparable. Quantitative differences were found in the sea- sonal amplitudes, which were greater for the regions with nutrient enrichment of the upper layer. Re- lationships were established between phytoplankton and mesozooplankton biomass for 8 provinces.

Absolute values of chlorophyll a concentration and its spatial and seasonal variations in the Black Sea were assessed by using satellite CZCS and in situ data. Since the satellite CZCS had operated for the 1978–1986 period, CZCS data was used for assessing the past state of the Black Sea just before the onset of drastic changes observed in late 1980s. The approach used for the calculation of the absolute values of chlorophyll a concentration from CZCS data was based on the direct comparison of in situ chlorophyll a data and those of CZCS and by applying the algorithm developed for the transformation of CZCS data into chlorophyll a values. CZCS Level 2 data related with pigment concentration having a spatial resolution of 1 km at nadir were used. The daily Level 3 files were derived by binning Level 2 values into 4-km grid cells and the monthly and seasonal Level 3 files were created by averaging the daily Level 3 files over the corresponding period. In situ chlorophyll a data were obtained by spectrophotometric and fluorometric methods in 15 scientific cruises over the 1978–1986 period. Total number of ship-measured data used for the comparison with those CZCS values was 590. Chlorophyll a concentration (Chl) was derived from CZCS values ( C ) with regression equations Chl= kC ; the coefficient of transformation k was calculated from six different data sets by taking into account distinctions between subregions and seasons. The reasons for difference in the k values have been analyzed. Statistical comparison of the chlorophyll a values measured in situ and those derived from CZCS data was based on log-transformed data and gave the following results: regression slope=0.842, regression intercept=−0.081, coefficient of determination ( R 2 )=0.806, root–mean–square error=0.195. The mean monthly chlorophyll a distributions derived from CZCS data over 1978–1986 have been constructed and the mean seasonal chlorophyll a values in different regions have been calculated and analyzed. The significant difference in chlorophyll concentration between the western shelf regions and the open part of the Black Sea has been demonstrated, especially in warm season. At almost all seasons, the highest chlorophyll concentration is observed in the western interior shelf region which is under strong influence of Danube. The summer mean chlorophyll concentration in this region is ∼18 times higher than that in the open parts and about nine times higher than in the eastern shelf region. The greatest seasonal variations are observed in the open part of the Black Sea: chlorophyll concentration in cold season is four to six times higher than in summer and three to five times higher than in April and October. To the contrary, in the western interior shelf regions, the concentration is higher in May–October (about twice than that in November–March). Seasonal variations in the western outer shelf regions are smoothed out as compared with both the western interior shelf and the open regions.

The proximate biochemical composition and metabolic rates of ctenophores Mnemiopsis leidyi and Beroe ovata from the Black Sea were examined with respect to starvation conditions. Although organic matter content in B. ovata was two times higher than that of M. leidyi (2.51 ±0.53 and 1.14 ±0.17 mg g-1 of wet weight, respectively), these species did not significantly differ in their biochemical composition. In both species protein formed about 80% of the total organic matter, lipids amounted to about 10%. Carbohydrate and amino acids measured separately made up less than 6.5% of the total organic matter. Under experimental starvation (18 days at 16—18°C for B. ovata and 8 days at 12.4°C for M. leidyi), wet weights of both ctenophore species were reduced by 9.4% and 9.3% d-1, respectively. The rate of organic matter decrease was nearly two times lower than that of wet weight being on average 5.9% d-1 in M. leidyi and 5.5% d-1 in B. ovata. There was no trend in percentage of the four major biochemical categories with starvation time. The glycogen content in polysaccharides reached maximum values in freshly collected ctenophores (76.0 ±7.9% in B. ovata, and 86.6% in M. leidyi), but it was reduced substantially (34.4 ±2.7% in B. ovata and 18.3—28.8% in M. leidyi) with starvation. Monosaccharide content, expressed as a percentage of total carbohydrate, decreased from 39.9% to 13.5% in B. ovata, and from 45.8% to 14.3—23.2% in M. leidyi. The relationship between respiration rate (R) and wet weight (W) of individuals during the starvation can be expressed by power function R = R1 Wk (r2=0.85—0.94; P>0.001) for both ctenophore species. On average, k values were 0.95 and 0.83 in B. ovata and in M. leidyi, respectively. By the end of the starvation, metabolic rate per unit wet weight decreased by 33% in B. ovata and 46% in M. leidyi. Organic matter utilization was almost totally explained by respiration of ctenophores in the experiments and exceeded metabolic requirements of studied species by 11% and 15%, correspondingly. As compared with Mnemiopsis, Beroe has better tolerance to starvation which explains to some extent the success of the species survival during prolonged periods of food shortage in the Black Sea conditions.

Data collected during cruises of the Former Soviet Union (in 1963-1989) and the British Atlantic meridional transect program (in 1995-1999) were used to analyse macroscale patterns in phyto- and zooplankton biomass, size structure, species diversity, chlorophyll a, and plankton bioluminescence in the macroscale anticyclonic gyre of the South Atlantic Ocean. The spatial pattern of bioluminescence intensity was in good agreement with that of remotely sensed (CZCS) chlorophyll a, phosphate, salinity, and copepod species diversity index distributions especially in terms of geographic inclinations of the isolines, both associated with the north-westward pattern off the South equatorial current. Among the 416 copepod species recorded in samples, 51 species were noted throughout the whole gyre. On the other hand, there were a number of species found only in one of the currents. The mesozooplankton biomass size spectra (calculated in carbon units), exhibited a fairly stable slope of the curve from the eastern periphery of the gyre to its centre. The British Atlantic meridional transect program meridional transect through the western part of the gyre showed mesozooplankton size spectra in greater detail between the equator and 50degrees S. Although the spectra change slowly along the transect as far as 36degrees S, there is a general trend toward increasing slopes from the equatorial region to the oligotrophic central gyre. The calculated phyto-to-zooplankton ratio indicated that for the tropical anticyclonic gyres, the mesozooplankton carbon biomass could be represented as the exponential function of the phytoplankton carbon., Les données collectées durant les campagnes de l’ex-URSS (1963 à 1989) et la section britannique dans l'Atlantique Sud (1995–1999) permettent d’analyser la distribution macro-échelle du phytoplancton et du zooplancton, la structure de taille, la diversité spécifique, la teneur en chlorophylle a, et la bioluminescence du plancton dans le tourbillon phytoplanctonique de l’Atlantique Sud. La répartition de la bioluminescence est en bon accord avec celle de la chlorophylle mesurée par télédétection (CZCS), les phosphates, la salinité et l’indice de diversité des copépodes. Cette répartition suit l’inclinaison des isolignes liée à la distribution générale du nord vers l’ouest au large du courant sud-équatorial. Parmi les 416 espèces de copépodes, 51 se rencontrent dans tout le tourbillon; à l’inverse, nombre d’espèces sont spécifiques à l’un des courants. La distribution en taille de la biomasse du mésoplancton, calculée en termes de carbone, suit une courbe à pente constante de la périphérie est au centre du tourbillon. Les sections réalisées par les anglais au travers de la partie ouest du tourbillon permettent de détailler cette répartition en taille du mézooplancton entre l’équateur et 50° S. Bien que le spectre se modifie lentement jusque vers 36° S, la tendance générale est bien à une élévation des pentes de la zone équatoriale au centre oligotrophe du tourbillon. Le taux calculé entre phytoplancton et zooplancton souligne que, pour les tourbillons anticycloniques tropicaux, la biomasse carbonée du mésozooplancton peut être représentée par une fonction exponentielle du carbone phytoplanctonique.

The analysis of vertical distribution of chlorophyll concentration (CHL) in deep-water regions of the Mediterranean Sea was carried out on the basis of historical data received during 1979 - 1987 in western and eastern parts of the sea. It was shown that for a deep-water part of the Mediterranean sea presence of two types of a vertical structure: one-modal, satisfactorily described by the Gaussian curve, and quasi-homogeneaus uniform distribution from a surface up to certain depth and subsequent downturn of concentration up to a minimum was characteristic for various regions and seasons. Parameters describing both types of vertical CHL distribution in the Mediterranean Sea in researched period were computed. Type of a vertical CHL profile and the parameters, describing its form, in each particular case in general corresponds to character of vertical distribution of pigment in moderate latitudes with expressed seasonal variability.

The effect is studied of different inorganic phosphorus concentrations on changes in growth rates of 7 diatom species isolated from the plankton of the Black Sea. All species examined increase their cell-division rate with increasing phosphorus concentration in the medium. The phosphorus concentrations have been determined above which division rate is not limited by phosphorus content in the medium. The non-limiting concentration amounts to V/V m =0.9. In the species studied, non-limiting concentrations ranged from 1 to 30 μg P/1. The highest values were obtained for relatively large-sized species. The ratio of cell surface to volume tended to be inversely related to the growth-rate-limiting concentration. Minimal values of phosphorus content in cells have been calculated to range from 0.6 to 4.0·10−17 g.at−P/μ−3. Based on a comparison of phosphate levels in the Black Sea with experimentally-derived rate-limiting concentrations, it is concluded that phosphorus does not limit the reproduction rate of phytoplankton in the more productive regions of the Black Sea or in the lower strata of the euphotic zone.

Coal-fired power generation in Vietnam is expected to grow rapidly over the next 15 years and become the most important source of electricity in Vietnam. At present, coal accounts for about 20% of Vietnam's power generation mix and it will rise to over 50% in 2030 if the coal-fired capacity is increased from 4,360 MW to 75,000 MW as planned. In this study we contrast the current CO 2 emissions from the existing sub-critical coal-fired plants in Vietnam, based on average operating efficiencies, with scenarios that assume the use of imported coal of varying grades instead of the use of domestic coal. We also explore how emissions could change with the adoption of supercritical- and ultra-supercritical combustion technologies. The results provide clear insights for policy-makers tasked with meeting Vietnam's future emissions standards.