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Observations of the aerosol particle number concentration in the marine boundary layer over the south-eastern Baltic Sea

Byčenkiene S., Ulevicius V., Prokopčiuk N., Jasinevičiene D.

Oceanologia

2013

No. 55 (3)

573--598

Continuous measurements of the aerosol particle number concentration (PNC) in the size range from 4.5 nm to 2 µm were performed at the Preila marine background site during 2008–2009. The concentration maxima in summer was twice the average (2650±50 cm-3). A trajectory-based approach was applied for source identification. Potential Source Contribution Function (PSCF) analysis was performed to estimate the possible contribution of long-range and local PNC transport to PNC concentrations recorded at the marine background site. The PSCF results showed that the marine boundary layer was not seriously affected by long-range transport, but that local transport of air pollution was recognized as an important factor. North Atlantic and Sea-Marine type clusters respectively represented 32.1% and 17.9% of the total PNC spectra and were characterized by the lowest PNCs (1080±1340 and 1210±1040 cm-3 respectively) among all clusters. Wavelet transformation analysis of 1-h aerosol PNC indicated that while the 16-h scale was a constant feature of aerosol PNC evolution in spring, the longer (∼60-h) scales appeared mainly over the whole year (except June). Principal component analysis (PCA) revealed a strong correlation between PNC and NaCl, highlighting the influence of sea-salt aerosols. In addition, PCA also showed that PNC depended on optical and meteorological parameters such as UVR and temperature.

Assessment of radionuclide migration and radiological human exposure at the closed near-surface radioactive waste repository

Gudelis A., Nedveckaite T., Prokopčiuk N., Filistovič V., Remeikis V., Motiejunas S.

Nukleonika

2010

Vol. 55, No. 2

251-259

The near-surface “RADON” type radioactive waste repository, installed in 1963 and designed to store radioactive waste formed in industry, medicine and scientific investigations, was closed in 1989 because it did not meet the requirements imposed on the radioactive waste disposal. A comparatively small amount of radioactive waste is stored in this repository, but the inventory comprises various kinds of waste: short-lived low-level radioactive waste, short-lived low and intermediate radioactive waste, long-lived intermediate and high-level radioactive waste. The possible site-specific radionuclide migration through the groundwater pathway as well as the human exposure are considered by the computer program RESRAD-OFFSITE in this paper. The analysis of the obtained data shows that out of all stored radionuclides only H-3, C-14 and Cl-36 exceeding the dose constraint of 0.2 mSv can be considered as dangerous. The monitoring carried out in the repository environment has shown the contamination of groundwater with radioactive tritium and a significant reduction of contamination after construction of additional protective engineering barriers. For the assessment of the contribution of separate site-specific parameters of the model taking into account uncertainties of the model and parameters to the annual effective dose, the computer code RESRAD-OFFSITE provides the possibility of applying the regression analysis. It has been determined that the aquifer lateral dispersion as well as the hydraulic gradient, the radionuclide activity concentration in the repository together with the rate of penetration into the environment and the precipitation amount have the largest influence on the assessment accuracy of annual effective doses.