Donatas Butkus

Triukšmo slopinimo sieneles efektyvumo ivertinimas

Santrauka Mechanizavus pramones ir žemes ūkio gamyba, didejant transporto srautams miestuose ir gyvenvietese, modernejant buitinei technikai, sparciai dideja akustinio diskomforto zonos. Triuksmo lygis darbo vietoje ar namu aplinkoje yra vienas pagrindiniu veiksniu, lemianciu komforto rodikli, todel vis daugiau demesio skiriama triuksmo procesu nagrinejimui. Triuksma kelia ir jūru uostu kroviniu stotys. Klaipedos uosto siaurineje dalyje vykdomi krovos darbai kelia dideli uostamiescio gyventoju susirūpinima. Viena is opesniu problemu yra is AB KLASCO biriuju trasu terminalo sklindantis triuksmas. Salia terminalo irengta triuksmo slopinimo sienele. Straipsnyje pateiktas sieneles efektyvumo ivertinimas, atlikus tyrimus taikant skaiciavimo, matavimo bei modeliavimo metodus. Triuksmo matavimo tyrimai atlikti naudojant triuksmamati Bruel&Kjaer mediator 2260. Is gautu rezultatu matyti, kad triuksmo lygis gyvenamojoje teritorijoje 3–6 dB virsija leistinasias higienos normos HN 33–1:2003 vertes dienos metu, taip p...

Chamber investigation and evaluation of acoustic properties of materials

Abstract Traffic‐generated noise accounts for 60–80% of the noise prevailing in towns. With the aim of reducing the impact of noise on humans, measures and methods of fighting noise in towns and residential areas should be developed. In the majority of cases, noise suppression walls (barriers) are one of the most suitable means in tows to reduce the dispersion of noise to residential territories. Acoustic properties of materials to be used for noise walls were investigated and, on the basis of the obtained findings, the most suitable materials with regard to noise reduction were proposed. A noise‐suppression chamber was designed and installed for the experimental investigation into acoustic properties. Separate materials (fibreglass, wood chipboard, gypsum cardboard, foam polystyrene) were used for the experiment by composing various structures of different modifications. With the aim of evaluating the capacity of different materials to suppress noise, a coefficient was used to evaluate noise suppression ...

Studies of 137cs transfer in soil‐fern system

Abstract Fern accumulates radionuclides in abundance, including 137Cs. Tranfer of 137Cs and 40K in plants which have different root systems (fern or grass), or have no roots at all (moss) was compared. Samplings were performed in regions contaminated with 137Cs after Chernobyl Nuclear Power Plant (ChNPP) accident in 1994 and 1997–2000. The male fern (Dryopteris filix‐mas) most prevailing in Lithuania was studied. Fern accumulates 137Cs more effectively than grass or moss. The average 137Cs activity concentration in fern is 180±60 Bq kg−1 and the transfer factor is 0,074 m2kg−1. The fern stipe accumulates 137Cs most of all (200±90 Bqkg‐1), the transfer factor is 0,087 m2 kg−1. Accumulation of 137Cs is influenced by the content of K in the soil. 137Cs and 40K activity concentrations in fern are higher than those in the soil what shows that fern accumulates 137Cs better than 40K. Fern can clean the soil because this plant accumulates radionuclides in its stipe rather than roots.

Sorption of heavy metals from polluted water and their migration in the system soil‐tree

Abstract Large amounts of various contaminants are transported via natural processes from technogenic pollution sources to air, water, soil and natural ecosystems. Heavy metals (HM) are very hazardous substances having long‐lasting impact on ecosystems. They have complex negative impact on human health, animals, flora and fauna at watercourses and microflora of wastewater. Often concentration of HM exceeds maximal available concentration in wastewater. HM enter forests in their wet and dry forms from local or outer atmosphere sources; they are also brought from seas alongside with biogens and sea salt or washed from putrid or putrescent plants that concentrate in the soil or they are brought by wind or water together with mineral particles. Monitoring of forests determined that contaminants, i e HM inhibit energetic status of a tree and cause increase of tree sensitivity to diseases. In this paper the most commonly met HM, such as Ni, Mn, Zn, Pb, Cu and Co, are analysed. Pollution with HM can be reduced, ...

Investigation of 90Sr acumulation in Pinewood (Pinus sylvestris L.)

Santrauka Pateikiami 90Sr medienoje tyrimo rezultatai, pagal kuriuos jis kinta nuo (0,03±0,01) Bq/kg iki (2,32±0,34) Bq/kg. Autoriai siūlo 90Sr sukauptam pusies medienoje kiekiui modeliuoti naudoti FORM modeli. Vidutinis skirtumas tarp tyrimo ir modelio rezultatu yra 13 %. Norint ivertinti visa sukaupta 90Sr medyje kieki, taikomas savitojo aktyvumo integralu sumavimo metodas, pries tai nustacius 90Sr savitojo aktyvumo ir medžio biomas0s prieaugio rysio funkcija. Pagal pasiūlyta modeli ivertinta, kad per 1950–2000 m. pusis sukaup0 620 Bq. Darbe yra ivertintas 90Sr pernasos is dirvožemio i paprastosios pusies mediena koeficientas. 1950–2000 m. laikotarpiu jis kito nuo (2,0±1,0) · 10−4 m2/kg iki (9,7±1,0) · 4m2/kg.

Influence of gamma radiation of indoor radon decay products on absorbed dose rate

Abstract A survey of absorbed dose rate and indoor radon concentration in multistorey houses was carried out. The main source of radon in such houses is construction materials. There is a relationship between absorbed dose rate and indoor radon concentration. This relationship is rather complicated and different for different premises. It depends on the geometry of premises and other characteristics which influence the distribution of indoor radon daughters. Increment of absorbed dose rate per unit of increment of indoor radon concentration depends on the concentration of indoor radon, floor where premises are situated, geometry of premises. The results of this study might help to assess the dose due to indoor radon which originates from construction materials.

INVESTIGATION OF HEAVY METAL AND RADIONUCLIDE DISTRIBUTION IN SILT OF LAKE DIDŽIULIS

Abstract The article deals with research of the ecological situation in Lake Didžiulis, located nearby the highway Vilnius–Kaunas (Trakai District); the most polluted locations in the lake were identified. Research of heavy metals (HM) and radionuclides in the lake silt is described. To research HM concentrations and the specific activities of radionuclides, the samples were collected from 12 bores in the most typical locations of the lake. The estimated HM concentrations in the silt of Lake Didžiulis vary within a wide range: Cr from 6.9 to 45.2 mg/kg, Ni from 20.4 to 55.7 mg/kg, Mn from 236 to 1362 mg/kg, Cu from 7.1 to 80.9 mg/kg, Pb from 24.4 to 87.8 mg/kg, Zn from 13.0 to 75.8 mg/kg. The HM concentrations in the lake silt do not exceed the maximum allowed concentrations (MAC) in the soil, whereas the concentrations of manganese, copper and lead in some samples are close to MAC. The counted specific activities of 40K fluctuate from 46 Bq/kg to 415 Bq/kg in the upper level silt and from 125 Bq/kg to 48...

Modelling vertical migration of 137Cs in Lithuanian soils

Abstract 137Cs vertical migration in soil was evaluated using two methods: evaluating migration parameters using the quasi‐diffusion model, and modelling vertical migration using VS2DI software package, which is intended for simulating transport of pollution in different types of soil. 137Cs distribution in soil was compared in elevated contamination “spots” in 1992 and 1999–2000. It was determined that 137Cs vertical distribution in soil has two maxima caused by the 137Cs global fallout due to nuclear weapon tests and by the fallout due to the ChNPP accident. 137Cs concentration simulated by VS2DI software package is close to the measured 137Cs concentration, especially to values measured in 1992. This shows that the software is able to simulate 137Cs vertical migration due to a single fallout. The quasi‐diffusion model is adequate for description of long‐term 137Cs vertical migration, and the results of measurements and calculations agreed within error limits. Parameters of long‐term vertical migration ...

Experimental research into the dispersion of railway traffi c noise in the environment and its modelling

Department of Environmental Protection, Vilnius Gediminas Technical University, Saulėtekio 11, LT-10223 Vilnius-40, Lithuania E-mail: pbalt@ap.vgtu.lt, butkus@ap.vgtu.lt, raimon@ap.vgtu.lt In recent decades, inadequacies between nature and human activities have become one of the most relevant social-economic problems. With the rapid development of industrialisation and urbanisation, the environmental pollution has greatly increased. In the majority of towns and settlements, noise is justly considered as an ecological problem. Th e Paneriai Railway Station was selected for the research as one of the most intensive by the number of passing trains. Th e analysis of the noise level caused by railway traffi c near the junction of the Paneriai Railway Station shows that at low frequencies (31.5–250 Hz) the permissible noise level (PNL) was exceeded by 2–5 dB. Th e fi ndings of research into noise caused by the passing railway transport show that the levels of the equivalent noise exceed by 4–8 dBA the noise levels permissible in living territories. Th e level of noise caused by passing trains is exceeded in the frequency range of 125–4000 Hz. Th e permissible noise level is exceeded by about 8 dB at the frequency of 500 Hz and 7 dB at the frequency of 1000 Hz. Th e generated model of noise dispersion from the railway traffi c to the living environment helped off er the noise reduction walls as a means of improving the living environment.

Research of Equivalent and Maximum Value of Noise Generated by Wind Power Plants

Abstract According to the Directive 2009/28EC of European Parliament and Council, dated April 23, 2009, Lithuania should strive for the part of renewable energy sources in the balance of electric energy to reach no less than 23% in the year 2020. The most favorable condition for development of wind energy in Lithuania is on a 50 km width zone by the seaside. Parks of wind power plants are expanding fast, but there is a lack of data about noise generated by wind turbines. The noise generated by the wind power plants is known to fluctuate and may spread up to 2 km beyond the wind power park. Research of noise generated by wind power plants was performed in the western part of Lithuania, near Rudaiciai village (Kretinga district) at the park of four wind power plants. Measurements were performed in cold and warm seasons when different wind speed, environment humidity and air temperatures dominated. The sound pressure levels of noise generated by wind power plants were established. The noise spread in the win...