Features of the distribution of the suspended form of iron in the water column of the Caspian Sea

Статья посвящена изучению распределения железа в водной взвеси Среднего Каспия. Актуальность работыопределяется необходимостью оценки естественного состоя­ния морской среды и фиксации ее базового состояния (в том числе различных форм химических элементов) для дальнейшего использования с целью мониторинга экологической ситуации на шельфе Каспийского моря в условиях интенсификации геологоразве­дочных работ и разработки месторождений нефти. Цель работы. Установить характерные особенности поведения взвешенного железа в водах Среднего Каспия. Материалы и методы работы. Изучался материал, отобранный в 1989-1990 годах в ходе выполнения рейсов исследовательских судов. Принадлежащих Каспийскому НИИ рыбного хозяйства, до начала освоения нефтегазовых месторождений. Он представлен отфильтрованными частицами взвеси из 178 проб воды, взятых из различных слоев водной толщи на 63 станциях. Определение содержаний железа проводилось на спектрографе PGS-2 способом испарения. Результаты работы. Минимальные концентрации взвешенной формы железа в поверхностном слое водной толщи установлены на участке внутреннего шельфа и подводного склона котловины Среднего Каспия, что связано с выносом твердых частиц дрейфовыми течениями. Концентрации взвешенной формы железа в поверхностном слое возрастают к середине моря, что обусловлено стягиванием взвешенных частиц центростремительными силами циклонального течения. Придонный слой отличается повышенными концентрациями взвешенной формы железа. Возле дельт рек они связаны с оседанием выносимых с суши твердых частиц. Аномально высокие содержания взвешенной формы железа в придонном горизонте центральной части Среднекаспийской котловины, фиксируемые на отдельных станциях, обусловлены поступлением железа с эманациями донных грязевых вулканов и его коагуляцией в условиях щелочной среды. В целом, с увеличением глубины наблюдается последовательный рост концентраций взвешенной формы железа. Это связано с изменением солености и усилением вертикальной стратификации (уменьшением солености поверхностного горизонта и увеличением солености глубоких слоев). Это приводит к коагу­ляции и флокуляции органических и металлор­ганических коллоидов и переводу растворенного железа во взвесь The article is devoted to the study of the distribution of iron in the water suspension of the Middle Caspian Sea. The relevance of the work is determined by the need to assess the natural state of the marine environment and fix its basic state (including various forms of chemical elements) for further use in order to monitor the environmental situation on the shelf of the Caspian Sea in the conditions of intensification of exploration and development of oil fields. Aim. To establish the characteristic features of the behavior of suspended iron in the waters of the Middle Caspian. Materials and methods. The material selected in 1989-1990 during the voyages of research vessels was studied. owned by the Caspian Research Institute of Fisheries, before the development of oil and gas fields. It is represented by filtered suspended particles from 178 water samples taken from various layers of the water column at 63 stations. Determination of iron content was carried out on the PGS-2 spectrograph by evaporation. Results. The minimum concentrations of the suspended form of iron inthe surface layer of the water column were established on the section of the inner shelf and the underwater slope of the Middle Caspian basin, which is associated with the removal of solid particles by drift currents. The concentrations of the suspended form of iron in the surface layer increase towards the middle of the sea, which is caused by the contraction of suspended particles by the centripetal forces of the cyclonic current. The bottom layer is characterized by increased concentrations of the suspended form of iron. Near river deltas, they are associated with the subsidence of solid particles carried out from the land. Abnormally high concentrations of suspended iron in the bottom horizon of the central part of the Middle Caspian basin, recorded at individual stations, are due to the influx of iron with emanations of bottom mud volcanoes and its coagulation in an alkaline environment. In general, with increasing depth, there is a consistent increase in the concentrations of the suspended form of iron. This is due to a change in salinity and an increase in vertical stratification (a decrease in the salinity of the surface horizon and an increase in the salinity of the deep layers). This leads to coagulation and flocculation of organic and organometallic colloids and the transfer of dissolved iron into suspension.

Geochemical composition of ice wedges in the Batagay yedoma

The subject of this research is the syngenetic ice wedges stripped in the Batagaika crater (67°34 '49" N, 134°46 ' 19 " E), located 10 km southeast of the Batagay settlement. The assessment of macroelement composition of ice was conducted using “Stayer” ion chromatograph (Russia), the chloride ion detection limit is 0.02 mg/l. The article examines the ionic and macroelement composition of ice in suspended and dissolved forms in the Late Pleistocene syngenetic ice wedge of the Batagay yedoma. A comprehensive geochemical research of the Batagaika crater is carried out for the first time. The author explores the upper and lower ice wedges of different age. The main conclusions are as follows: 1) mineralization of Late Pleistocene ice wedge of the Batagay yedoma ranges from 66.56 to 424.8 mg/l, from ultra-fresh to slightly salted; by ionic composition, the ice is bicarbonate-calcium and corresponds to the snow formed under the influence of continental air masses; 2)  the share of Ca contained in the dissolved form does not exceed 20-30%’ as far as other elements, the share of Mg, K, Na, Al, Fe, Mn in the suspended form is over  90%; 3) by mineralization, the Pleistocene ice of Batagay yedoma coincides with the previously studied Pleistocene ice wedges of Yakutia and the Interior Alaska.

FEATURES OF PHOSPHORUS ACCUMULATION IN THE BOTTOM SEDIMENTS OF THE IVANKOVO RESERVOIR

The distribution of phosphorus in the bottom sediments of the Ivankovo reservoir, the forms of phosphorus and its content in different size fractions of the sediment were studied. It is shown that the main part of phosphorus is in mineral form and is contained in the clay fraction of sediment, which increases the risk of secondary pollution of water with phosphorus, due to its flow from bottom sediments in suspended form in the active dynamic zones of the reservoir. The estimation of the diffusion input of soluble forms of phosphorus from the bottom sediments of the reservoir accumulation zones was performed.

Mercury accumulation in suspended matter of foam and water of the Black Sea

The ability of suspended matter to concentrate mercury may be the prevailing factor in Black Sea purification. As a result of sedimentation, suspended particles transport pollution from the surface layer of the water column and, as a consequence, can deposit them in bottom sediments, thus participating in self-purification of marine area. Suspended matter, as a dispersed phase of an aqueous medium, considered as a heterogeneous dispersed system, can be more saturated with mercury than water itself, as a dispersion medium. In this work, contribution of dissolved and suspended forms of mercury to its total content was determined, and concentrating ability of suspended matter relative to mercury, which affects biogeochemical self-purification of waters from mercury, was estimated. All water samples were separated into filtrate and suspension by filtration through nucleopore filters with a pore diameter of 0.45 μm. Measurements of mercury concentration were carried out using a Hiranuma-1 analyzer by the method of atomic absorption spectrophotometry. Concentration of dissolved mercury in water was determined per liter, while in suspended matter – per liter and per gram of dry weight. Prevalence of dissolved form of mercury was revealed regardless of the season, with its percentage varying from 66.3 to 85.8 % of total mercury concentration. Average content of suspended form varied in the range of 14.2–33.7 % of its total form. Values of the dry weight of suspended matter (mss) varied from 0.1 to 15.0 mg·L−1 over the entire period studied, and an accumulation coefficient of mercury in suspended matter (Kss) varied from n·10³ to n·107. Significant contribution of suspended form of mercury in sea foam to its total content in stormy weather was established. With dry weight of suspended matter in seawater reaching 9.6 mg·L−1, the concentration of dissolved form of mercury reached 55 ng·L−1, and the concentration of suspended one reached 20 ng·L−1. In sea foam, the concentration of suspended sedimentary matter was of 895.2 mg·L−1; mercury concentration reached 200 ng·L−1 in dissolved form and 260 ng·L−1 in suspended one. Total mercury concentration in sea foam in this case exceeded the threshold limit value (100 ng·L−1) for seawater. The accumulation coefficient of mercury in suspended matter (Kss) was 3.8·104 for seawater and 1.5·103 for foam. Such distribution of mercury in sea suspension, foam, and water, as well as Kss values obtained, may indicate high significance of suspended matter in self-purification of marine area. At a low mercury content in water, the concentrating ability of suspended matter, characterized by relatively high values of its mercury accumulation coefficient, becomes a very significant factor in the sedimentation self-purification of waters from mercury; however, with an increase in water pollution with mercury, the effect of this factor decreases.

Biogeochemical specialization of macrophytes and their role as a biofilter in the Selenga delta

This study aims to evaluate the biofiltration ability of higher aquatic vegetation of the Selenga delta as a barrier for heavy metals and metalloids (HMM) flows into the Lake Baikal. Main aquatic vegetation species have been collected from deltaic channels and inner lakes: Nuphar pumila, Potamogeton perfoliatus, P. pectinatus, P. natans, P. friesii, Butomus umbellatus, Myriophyllum spicatum, Ceratophyllum demersum, Phragmites australis. Analysis of the obtained data showed that regardless of the place of growth hydatophytes spiked water-milfoil (M. spicatum) and the fennel-leaved pondweed (P. pectinatus) most actively accumulate metals. Opposite tendencies were found for helophytes reed (Ph. australis) and flowering rush (B. umbellatus), which concentrate the least amount of elements. This supports previous findings that the ability to concentrate HMM increases in the series of surface – floating – submerged plants. Regarding river water, the studied macrophyte species are enriched with Mn and Co, regarding suspended matter – Mo, Mn and B, regarding bottom sediments – Mn, Mo and As. We identified two associations of chemical elements: S-association with the predominant suspended form of migration (Be, V, Co, Ni, W, Pb, Bi, Mn, Fe and Al) and D-association with the predominant dissolved form of migration (B, U, Mo, Cr, Cu, Zn, As, Cd, Sn and Sb). Due to these associations three groups of macrophytes were distinguished – flowering rush and reed with a low HMM content; small yellow pond-lily and common floating pondweed with a moderate accumulation of S-association and weak accumulation of D-association elements; and clasping-leaved pondweed, fennel-leaved pondweed, and pondweed Friesii accumulating elements of both S and D groups. The results suggest that macrophytes retain more than 60% of the total Mn flux that came into the delta, more than 10% – W, As, and from 3 to 10% B, Fe, Co, Mo, Cd, V, Ni, Bi, Be, Cu, Zn, Cr, U, Al. The largest contribution is made by the group of hydatophytes (spiked water-milfoil and pondweed), which account for 74 to 96% of the total mass of substances accumulated by aquatic plants.

Peculiarities of migration of mercury in water and bottom sediments of the estuary area of the Red River (Vietnam)

The paper assessed the content of mercury in water and bottom sediments in the mouth area of the Red River of Vietnam. Given the spatial distribution of mercury in the dissolved, suspended forms and in sediments. The studies were conducted at 30 stations 2 times a year (during the flood and low-water periods) in 2014-2016. Samples of bottom sediments were collected in the surface layer. The spatial distribution of mercury was carried out using the kriging method in ArcGIS 10.2.2. During the study period it was found that the concentration of mercury in the water of the Red River varies from 0,05 to 0,08 μg/l during low-water periods and 0,07 to 0,11 μg/l during the flood period. Towards the sea, the concentration of dissolved mercury decreased. Mercury concentrations in suspended form and bottom sediments increase towards the sea and reach a maximum in the marginal filter. In river waters, the main forms of mercury existence are dissolved and suspended, and in the marginal filter - in bottom sediments. The bottom sediments of the estuary area of the Red River are distinguished by a higher content of Hg compared to uncontaminated soils in reservoirs of temperate and northern latitudes, as well as with bottom sediments of water bodies in another region of Vietnam.

Sintesis biodiesel rute non-alkohol menggunakan Candida rugosa lipase dalam bentuk tersuspensi

Non-alcoholic route biodiesel synthesis using suspended Candida rugosa lipaseBiodiesel synthesis using biocatalyst can improve the disadvantage of alkali catalyst. Biocatalysts are not homogeneously mixed, so its separation is easy and it is also able to direct the reaction specifically without any unwanted side reactions. However, the application of biocatalysts in alcoholic environment degrades the biocatalyst quickly, and its stability suffers. To solve this problem, this research proposes to perform biodiesel synthesis through a non-alcohol route so that the activity and stability of the biocatalyst can be preserved. The biocatalyst used was Candida rugosa lipase in suspended form. Methyl acetate which served as alkyl group source was reacted with triglycerides from palm oil. The reaction was performed in a batch reactor, and HPLC was used to analyze reactants and product concentrations. Research results indicated that more than 86% of fatty acid chains from the palm oil triglycerides were converted to biodiesel at a biocatalyst concentration of 4 %-wt of the substrate, oil:alkyl molar ratio of 1:12, and reaction period of 50 hours. Furthermore, the kinetic data obtained using suspended enzyme, were also shown by concentration profile of tri-, di-, monoglycerides and biodiesel versus time in 50 hours reaction time.Keywords: biodiesel synthesis, interesterification, Candida rugosa lipase, non-alcohol route, triglycerideAbstrakSintesis biodiesel menggunakan biokatalis mampu memperbaiki kelemahan katalis alkali, yaitu tidak bercampur homogen, sehingga pemisahannya mudah dan mampu mengarahkan reaksi secara spesifik tanpa adanya reaksi samping yang tidak diinginkan. Namun penggunaan biokatalis di lingkungan beralkohol menyebabkan biokatalis terdeaktivasi secara cepat dan stabilitasnya menjadi buruk. Untuk menyelesaikan masalah tersebut, dalam riset ini diusulkan melakukan sintesis biodiesel melalui rute non-alkohol agar aktivitas dan stabilitas biokatalis tetap tinggi. Biokatalis yang digunakan adalah Candida rugosa lipase dalam bentuk tersuspensi. Metil asetat sebagai pensuplai gugus alkil direaksikan dengan trigliserida dari minyak kelapa sawit. Reaksi dilakukan dalam reaktor batch dan HPLC digunakan untuk menganalisa reaktan dan produk. Hasil penelitian menunjukkan bahwa lebih dari 86% rantai asam lemak dari trigliserida minyak kelapa sawit berhasil di konversikan menjadi biodiesel pada kondisi konsentrasi biokatalis sebesar 4 %-wt substrat, rasio mol minyak:alkil sebesar 1:12 selama 50 jam reaksi. Selanjutnya, data kinetika menggunakan enzim tersuspensi juga ditunjukkan melalui profil konsentrasi tri-, di-, mono, dan biodiesel terhadap waktu selama 50 jam.Kata Kunci: sintesis biodiesel, interesterifikasi, Candida rugosa lipase, rute non-alkohol, trigliserida

Tribo-Investigations on Oils With Dispersants and Hexagonal Boron Nitride Particles

A dispersant is almost an unavoidable additive in engine oils since it helps to keep the carbonaceous particles in a suspended form. Dispersants can be multifunctional and can therefore interfere with the functions of other additives either synergistically or antagonistically. The present work investigated the influence of four dispersants (with and without particles of hexagonal boron nitride (hBN) on selected lubrication-related properties of the oils using four ball tester. Particles of hBN, though known as effective anti-wear (AW) and anti-friction (AF) additives, did not prove effective in oil in the presence of dispersants. On the other hand, it proved to be a good extreme pressure (EP) additive by showing 27% improvement in weld load (WL). Worn surfaces were examined using scanning electron microscopy (SEM), energy dispersion X-ray analysis (EDAX), and Raman spectroscopy.