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Date submitted2024-03-30
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Date accepted2024-06-13
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Date published2024-07-04
Organotin pollutants in emerging coastal-marine sediments of the Kaliningrad shelf, Baltic Sea
Based on two years of monitoring of modern bottom sediments of two sections of the Kaliningrad shelf of the Baltic Sea – “Curonian Spit” and “Northern Sambian” – an assessment of the sources of pollution with organotin compounds (OTs) and heavy metals was carried out. The content of individual organotin compounds and OTCs spectra obtained by gas chromatography with mass spectrometry of relatively coarse-grained bottom sediments indicate the presence of organotins in significant quantities – the total OTs content (ΣOTs) is from 0.6 to 8.3 ng/g. However, the content of tributyltin (TBT), the main component of anti-fouling systems for marine vessels and the most dangerous endocrine-disrupting compound among the hazardous substances for marine ecosystems, is at a low level (0-2.3 ng/g) in all studied samples and has not increased over the two-year observation period (biodegradation index 1.7-12.4). At the same time, the presence of abnormally high concentrations of mono-, triphenyl- and tricyclohexyltin in the sediments of the ”Northern Sambian” site (up to 30, 7 and 6.4 ng/g, respectively) indicates an additional source of pollution of coastal waters and shelf sediments (for example, plastic litter and agricultural runoff). The absence of significant shipping in the study areas ensures a consistently low level of pollution with tributyltin and its derivatives (less than 0.3 and 2.3 ng/g of TBT in 2017 and less than 0.1 and 1.3 ng/g in 2018 for the sites “Curonian Spit” and “Northern Sambian”, respectively), which indicates the activity of the processes of TBT transformation and self-cleaning of sandy sediments. However, the identified trends and their predictive accuracy require long-term observation and monitoring of the sediment environment using data on the deep-water part of the shelf, enriched in clay and humus components.
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Date submitted2023-03-20
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Date accepted2023-09-20
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Date published2023-10-27
Experimental simulation of a system of swamp biogeocenoses to improve the efficiency of quarry water treatment
Mining activities were producing large quantities of wastewater contaminated with nitrogen compounds and metals. With insufficient treatment, these pollutants are released into the environment and have a toxic effect on living organisms. Constructed wetlands are now widely adopted as wastewater treatment systems because of the combination of physical, chemical and biological processes for the removal of contaminants. In this study, an experimental system was modeled to improve the efficiency of the quarry wastewater treatment of a mining enterprise by sharing the higher aquatic vegetation: broad-leaved cattail (Typha latifolia L.), common water-plantain (Alisma plantago-aquatica L.), jointed rush (Juncus articulatus L.) and lower aquatic vegetation (Chlorella sp.). Concentrations of nitrogen compounds and metal were analyzed both in the model and in the treated solution of quarry wastewater for calculation of treatment efficiency. Concentrations of the pollutants in the tissues of the higher aquatic vegetation were analyzed to assess the accumulation capacity and efficiency of translocation of the pollutants. The results of the experimental study showed the practical applicability of the constructed integrated treatment system to reduce the concentration of pollutants in quarry wastewater, as well as increasing the efficiency of treatment by introducing lower aquatic vegetation into the system
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Date submitted2022-09-30
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Date accepted2023-02-13
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Date published2024-02-29
Improving the efficiency of oil vapor recovery units in the commodity transport operations at oil terminals
- Authors:
- Vladimir V. Pshenin
- Gulnur S. Zakirova
In this paper the problem of losses from evaporation of light fractions of hydrocarbons during loading operations of tanker fleets vessels is considered. It was found that there is no unified approach to modeling the system “tanker – gas phase pipeline – vapor recovery units” in open sources. The absence of a generally recognized model makes it impossible to scientifically justify the application of instruments to reducing losses and the development of corresponding measures. In work it is showed that the dynamics of growth of pressure in the inner tanker capacity is described by a differential equation, considering for non-stationary essence of the process. This equation is converted to a non-dimensional form and investigated in relation to the similarity criteria of this system. This research has allowed to establish unambiguously the general character of pressure changes in the inner tanker capacity, and to predict the peak values of its growth at the initial stage of the loading operation. The obtained equations were tested on real tanker loading data and showed satisfactory convergence with the experimental data. At different stages of the loading opera-tion the component composition of vapor changes, which is shown by chromatographic analysis of the gas mixture. With the availability of a model of hydrocarbon vapor displacement from the inner of tanker, it is possible to propose measures to minimize the negative impact on the environment and return valuable vapors of the product to the technological chain of transportation.
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Date submitted2017-08-30
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Date accepted2017-11-23
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Date published2018-02-22
Basic provisions and problems of ELW technology for the manufacture of aluminum-magnesium alloys constructions
- Authors:
- E. I. Pryakhin
- N. I. Sharonov
Existing problems of electron beam welding of aluminum alloy constructions are considered. For research purposes, the aluminum-magnesium alloy of grade 1561 up to 60 mm thick was used. The thermal field in the heat influence zone is studied experimentally and analytically on the basis of the finite element method (the «Ansys» program). The effect of electron beam movement (scanning) influence on the quality of welded connections and the surface of the welded parts was studied. On the basis of metallographic studies and mechanical tests of welded metal, it is proved that high quality of welded joints is ensured when the beam moves along a curve of the «compressed brackets» shape. A special generator is designed to control the electron beam, which allows to implement a new type of scanning (compressed brackets). The fundamentals of welding technology for alloy 1561 up to 60 mm thick are outlined. Specific recommendations are given, and two new methods are proposed that will allow the successful use of the developed technology in factories in the production of new products and in the repair processes. Examples and analysis of thermal cycles obtained by calculation and experimental method are given. The patterns of heat distribution along the trajectory of the beam movement for different types of scanning are established. The main types of defects in the formation of the welded joints and those formed in the metal during crystallization are considered. Their interrelation with the parameters of the welding mode is shown.
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Date submitted2010-07-07
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Date accepted2010-09-06
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Date published2011-03-21
Improvement of quality of dissimilar welded joints made of pipelines steels by application of vibromechanical treatment in welding
- Authors:
- O. F. Khafizova
The article describes opportunity of improvement of physical-mechanical properties of welded joint made of different strength grade pipeline steels (Steel 20 of K42 strength grade and 16ГС – K52) by applying vibration during the welding cycle. It’s shown that maximal positive effect is achieved by vibration frequency approximating to natural-vibration frequency of welded construction.
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Date submitted2010-07-15
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Date accepted2010-09-13
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Date published2011-03-21
Experimental setup for research Influence of vibromechanical treatment on mechanical properties of welded joints
- Authors:
- O. F. Khafizova
- V. I. Bolobov
The description of developed experimental setup for welding product that made of pipeline steels with application of applying vibration with intended frequency approximating to natural-vibration frequency of welded construction unit of pipelines during the welding cycle is presented.
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Date submitted2009-09-08
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Date accepted2009-11-18
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Date published2010-06-25
Anodic bonding method for adhesion enhancement of conducting films to dielectric substrates
- Authors:
- A. G. Syrkov
- N. S. Pshchelko
The appearance of great pulling electric fields at anodic bonding process with a conductor surface to ionic dielectric turns out to be possible due to the interlayer polarization developing in dielectric under the action of electric voltage. This results in a negative charge accumulation in a layer of small thickness beside anode. Thus applied electric voltage is distributed not through the whole thickness of a dielectric, but in fact is applied to a narrow area of the three-dimensional charge beside anode. Arising strong electric fields force the connected materials to unite. In the present work it is shown that use of the discussed technology allows to increase considerably adhesion of conducting films to dielectric substrates both in the process of their deposition and after it.