Passive admixture transfer peculiarity at the Lithuanian coast of the Baltic Sea ; Pasyviųjų priemaišų pernašos ypatumai Baltijos jūros Lietuvos priekrantėje
Asta DAUNARAVI ČIEN Ė PASSIVE ADMIXTURE TRANSFER PECULIARITY AT THE LITHUANIAN COAST OF THE BALTIC SEA Summary of Doctoral Dissertation Technological Sciences, Environmental Engineering and Landscape Management (04T) 1430 Vilnius 2007 VILNIUS GEDIMINAS TECHNICAL UNIVERSITY Asta DAUNARAVI ČIEN Ė PASSIVE ADMIXTURE TRANSFER PECULIARITY AT THE LITHUANIAN COAST OF THE BALTIC SEA Summary of Doctoral Dissertation Technological Sciences, Environmental Engineering and Landscape Management (04T) Vilnius 2007 Doctoral dissertation was prepared at Vilnius Gediminas Technical University in 2003–2007. Scientific Supervisor Prof Dr Habil Dmitrijus STYRO (Vilnius Gediminas Technical University, Technological Sciences, Environmental Engineering and Landscape Management – 04T). Consultant Assoc Prof Dr Jonas KLEIZA (Vilnius Gediminas Technical University, Physical Sciences, Mathematics – 01P). The dissertation is being defended at the Council of Scientific Field of Environmental Engineering and Landscape Management at Vilnius Gediminas Technical University: Chairman Prof Dr Habil Pranas BALTR ĖNAS (Vilnius Gediminas Technical University, Technological Sciences, Environmental Engineering and Landscape Management – 04T).
Asta DAUNARAVIČIENĖPASSIVE ADMIXTURE TRANSFER PECULIARITY AT THE LITHUANIAN COAST OF THE BALTIC SEA Summary of Doctoral Dissertation Technological Sciences, Environmental Engineering and Landscape Management (04T)
Vilnius 2007
1430
VILNIUS GEDIMINAS TECHNICAL UNIVERSITYAsta DAUNARAVIČIENĖPASSIVE ADMIXTURE TRANSFER PECULIARITY AT THE LITHUANIAN COAST OF THE BALTIC SEA Summary of Doctoral Dissertation Technological Sciences, Environmental Engineering and Landscape Management (04T)
VILNIAUS GEDIMINO TECHNIKOS UNIVERSITETAS Asta DAUNARAVIČIENĖPASYVIŲJŲPRIEMAIŲPERNAOS YPATUMAI BALTIJOS JŪROS LIETUVOS PRIEKRANTĖJE Daktaro disertacijos santrauka Technologijos mokslai, aplinkos ininerija ir kratotvarka (04T)
Vilnius2007
Disertacija rengta 20032007 metais Vilniaus Gedimino technikos universitete. Mokslinis vadovas prof. habil. dr. Dmitrijus STYRO (Vilniaus Gedimino technikos universitetas, technologijos mokslai, aplinkos ininerija ir kratotvarka 04T). Konsultantas doc. dr. Jonas KLEIZA(Vilniaus Gedimino technikos universitetas, fiziniai mokslai, matematika 01P). Disertacija ginama Vilniaus Gedimino technikos universiteto Aplinkos ininerijos ir kratotvarkos mokslo krypties taryboje: Pirmininkas prof. habil. dr. Pranas BALTRĖNAS Gedimino technikos (Vilniaus universitetas, technologijos mokslai, aplinkos ininerija ir kratotvarka 04T). Nariai: prof. habil. dr. Donatas BUTKUS(Vilniaus Gedimino technikos universitetas, technologijos mokslai, aplinkos ininerija ir kratotvarka 04T), dr. Benedikta LUKIENĖ(Fizikos institutas, fiziniai mokslai, fizika 02P), habil. dr. Jonas MAEIKA(Geologijos ir geografijos institutas, fiziniai mokslai, geologija 05P), doc. dr. Saulius VASAREVIČIUS(Vilniaus Gedimino technikos universitetas, technologijos mokslai, aplinkos ininerija ir kratotvarka 04T). Oponentai: doc. dr. Aloyzas GIRGDYS(Vilniaus Gedimino technikos universitetas, technologijos mokslai, aplinkos ininerija ir kratotvarka 04T), habil. dr. Elena Danutė MARČIULIONIENĖ institutas, (Botanikos biomedicinos mokslai, ekologija ir aplinkotyra 03B). Disertacija bus ginama vieame Aplinkos ininerijos ir kratotvarkos mokslo krypties tarybos posėdyje 2007 m. gruodio 14 d. 13 val. Vilniaus Gedimino technikos universiteto senato posėdiųsalėje. Adresas: Saulėtekio al. 11, LT-10223 Vilnius, Lietuva. Tel.: (8 5) 274 4952, (8 5) 274 4956; faksas (8 5) 270 0112; el. patas doktor@adm.vgtu.lt Disertacijos santrauka isiuntinėta 2007 m. lapkričio 14 d. Disertaciją galima periūrėti Vilniaus Gedimino technikos universiteto bibliotekoje (Saulėtekio al. 14, LT-10223 Vilnius, Lietuva). VGTU leidyklos Technika 1430 mokslo literatūros knyga.
General Characteristic of the Dissertation Topicality of the problem The evaluation of the passive admixture transfer in the marine environment is very significant from the point of view of environmental protection. A particular attention is devoted to the Baltic Sea ecological state, which is strongly influenced by the peculiarities of the sea bottom, weak connection with the World Ocean, climatic and hydrometeorological conditions. During the recent decades, the tendency of increment of the amount of anthropogenic pollutants is observed. The development of nuclear energetics and technology inevitably causes the spread of radionuclides of technical origin in the marine environment. The major attention is paid to the investigation of the radionuclide 137Cs distribution, since the investigations show the high values of the volumetric activity of this radionuclide to be present in the sea water thus far. Besides that,137Cs radionuclide can be used as a tracer in investigations of the migration of other passive admixtures in the Baltic Sea water. Quite a number of scientists research the problems related with the amounts of the radionuclide of technical origin, their spread and impact on the marine environment. However, the works considering a problem of the variations of volumetric activity of radionuclides and their transfer in the coastal waters of the Baltic Sea practically are not encountered. Considering that, the volumetric activity of radionuclide137Cs in the coastal surface waters of the Lithuanian territorial zone of the Baltic Sea was determined, and the hydrometeorological parameters were evaluated as well. The volumetric activity of the radionuclide137Cs in the Baltic Sea water is not observed to be stationary, consequently it is very important to choose proper methods for the radionuclide activity determination of and evaluate the tendencies of its variations. After doing the evaluation of the changes in volumetric activity of radiocaesium in the coastal waters, the possibility of modeling and forecast of location of the appeared pollution source, its power and transfer direction arises. Moreover, the investigations are valuable for assessment of impact of the radionuclide on the sea flora and fauna, since137Cs is accumulated in fish (analogue of potassium), and the process is considered to be particularly characteristic for marine ecosystems. Aim of the work 1.determine the tendency of the change in volumetric activity ofTo radionuclide137Cs and evaluate the factors conditioning obtained values in the coastal waters of the Lithuanian territory of the Baltic Sea.
5
2.On the basis of the results of experimental investigations and mathematical modeling, to carry out the search of the imaginary source of passive pollutant (radionuclide137Cs) and evaluate the coincidence of theoretical and experimental values of volumetric activity in coastal waters. 3.To forecast future possible consequences in the Baltic Sea of the action of point137Cs pollution sources. Tasks of the work 1.To carry out the analysis of the scientific literature on the amounts of radionuclide137Cs, their distribution and variations in the marine environment.2.a consecutive long-term research of variations of theTo carry out radionuclide137Cs volumetric activity in the coastal waters of the territory of Lithuania of the Baltic Sea in different year seasons. 3.To evaluate the impact of hydrometeorological conditions on the transfer of radionuclide137surface waters of the Baltic Sea.Cs in the 4.choose an apply a theoretical scheme that would enable toTo determine quickly and reliably the peculiarities of the transfer of passive admixture in explanation of the formation of artificial radionuclide137volumetric activity field in the coastal waters of theCs Baltic Sea. 5.After evaluation of the experimentally determined hydrological parameters, to carry out the multifold calculations of the transfer of passive admixture in order to determine the optimal coincidence of theoretical and experimental values of the volumetric activity of radionuclide137Cs in the coastal territorial waters of Lithuania of the Baltic Sea. 6.To compare the theoretical results of the volumetric activity of radiocaesium with the values determined experimentally in the coastal waters. Scientific noveltyThe complex research of the volumetric activity of radionuclide137Cs in the surface coastal water of the Baltic Sea, in the territory of Lithuania, was carried out. When performing the research: 1.the long-term variations of the volumetric activity of radionuclide 137Cs in the coastal waters near Juodkrantėduring different seasons of the year period 19972006 were evaluated;
6
2.the mathematical model of the transfer of passive admixtures in the sea water was constructed and applied for the southeastern part of the Baltic Sea and the coastal zone, with the help of which it is possible to forecast the location of pollutants source, its power, and to evaluate the formation of the volumetric activity field in the coastal waters of the Baltic Sea; 3.the passive pollutant transfer duration and direction, in which the pollutant concentrations acquire maximum values under the action of pollutant sources of different power and natural meteorological conditions, are evaluated. Practical value According to the variations of the volumetric activity of radionuclide137Cs in the coastal zone, measured in the work, it is possible to forecast the factors determining the increase of volumetric activity in the open waters of southeastern part of the Baltic Sea. The constructed mathematical model, requiring not much time and costs, allows determining the location of the accumulation, distribution in space and time of passive admixtures. When changing the initial data, initial and boundary conditions, the model can be applied for any part of the Baltic Sea, and for the investigation of other water reservoirs as well. If the location of the source of a pollutant is defined in time, it is possible to avoid, warn or leastwise partially reduce the negative consequences in the marine ecosystem. Defended propositions1.The volumetric activity of radionuclide137Cs is not permanent in the coastal waters of the Lithuanian zone of the Baltic Sea, i e, it increases, decreases, and not always coincides with the radioactive background. In 20042006, its volumetric activity was changing in the range from 27 to 94 Bq/m3. 2.The variation of the volumetric activity of radionuclide137Cs in the coastal waters depends on the hydrometeorological circumstances (direction and speed of the wind, direction of the current), however its dependence on the specific electric conductivity and temperature of the water is not observed. 3.The mathematical program is constructed, which, after the estimation of the variations of the volumetric activity of radionuclide137Cs in the coastal waters and the meteorological parameters, can be used for modeling and forecast of the location and power of a point source of pollutants.
In this chapter the mathematical models describing the spread of passive admixtures in the hydrosphere are presented, the peculiarities of these models are analyzed. 2. The Objective of the Research and the Methods Used The researches of the Nuclear Hydrophysics laboratory of Vilnius Gediminas Technical University have determined that the absolute values of VA of radionuclide137Cs in the coastal waters of the Baltic Sea, measured in the long-term monitoring station near Juodkrantė, coincide with the VA values registered in the waters of the southeastern part of the proper sea. Consequently, there is fairly enough to do measurements of radionuclide VA in the coastal waters in order to evaluate the level of radioactive contamination in the proper sea. The specimens of the sea surface water for determining VA of137Cs were sampled in spring, summer and autumn seasons in the Baltic Sea at the distance of 10 m from the seashore of Lithuania at 0.5 meter depth. The minimum volume of the analyzed water specimen is 4050 liters. The temperature, specific electric conductivity, water current direction, wind speed and direction were registered during the time of sampling. During the whole research period, the determination of VA of radionuclide 137Cs in the coastal surface waters of the Baltic Sea were carried out using a single technique-radiochemical analysis and the same type of measuring equipment, namely, gamma-spectrometric equipment (gamma spectrometer CANBERRA with semiconductor HPGe detector). This research technique consists of some main stages: the concentration of radionuclide137Cs together with a stable carrier, sample cleaning, and activity measuring according to γradiation. The methods error is 10 %. The mathematical model was constructed and applied for theoretical assessment of the passive admixtures transfer in the southeastern part of the Baltic Sea and the coastal waters. When constructing the model, the sedimentation velocity was neglected because of its insignificance in comparison with other factors; and under the changing meteorological situations and owing to the complicated sea bottom conformation, the sedimentation velocity can acquire an opposite sign. The vertical component of turbulent diffusion is not accounted in the model. The effect of the vertical diffusion is negligible in comparison with the horizontal one, since the value of the horizontal turbulent diffusion coefficient (200 m2/s) is higher by six orders than that of the vertical turbulent diffusion (0.8 × 10-4m2/s). Therefore the plane turbulent diffusion equation is used in the model:
9
(2.2)
∂ ∂C=div(KgradC)−vgradC, (2.1) whereC = C(x, y, t) the concentration of the admixture; isv=v(x, y) is the vector velocity of the water mass movement;Cis the concentration of a passive admixture source;Kis the coefficient of turbulent diffusion. A steady-state model is used for the calculation of velocity fields: 1 div(H13gradψ)=2arotz⎛⎝⎜TH⎞⎠⎟, ψΓC=0, ∂∂ψnΓW=0, whereψ =ψ(x, y) is the function of the total flows;ais the coefficient of vertical change;T =(Tx,Ty) wind stress;is the tangential vector ofH is the depth of the sea. After calculating the function of the totals flowψ= (x, y)(m3/s) for every node of the net area, the velocity of water movement on the sea surface is calculated using the following formulae: =HT−3∂v=HTy+3∂∂, (2.3) u4ax2H∂y4,a2 hereuis the velocity of water movement inxdirection (m/s),vis the velocity of water movement inydirection (m/s). The effectiveness of the mathematical model can be verified with the help of a passive admixture, namely, artificial radionuclide137Cs, since the radionuclide exists in the ionic form in the sea water and is found in the whole marine area. 3. Mathematical Model Using the formulae presented in Chapter 2, the mathematical model is constructed and applied for investigation of the transfer of a passive admixture in the surface waters of the southeastern part of the Baltic Sea and the surface coastal waters under the action of the point pollution source of137Cs. The