The incidence of upper respiratory infections in children is related to the concentration of vanadium in indoor dust aggregates.

Background: It has been reported that the disease-initiated and disease-mediated effects of aerosol pollutants can be related to concentration, site of deposition, duration of exposure, as well as the specific chemical composition of pollutants. Objectives: To investigate the microelemental composition of dust aggregates in primary schools of Vilnius and determine trace elements related to acute upper respiratory infections among 6-to 11-year-old children. Methods: Microelemental analysis of aerosol pollution was performed using dust samples collected in the classrooms of 11 primary schools in Vilnius from 2016 to 2020. Sites included areas of its natural accumulation behind the radiator heaters and from the surface of high cupboards. The concentrations of heavy metals (Pb, W, Sb, Sn, Zr, Zn, Cu, Ni, Mn, Cr, V, and As) in dust samples were analyzed using a SPECTRO XEPOS spectrometer. The annual incidence rates of respiratory diseases in children of each school were calculated based on data from medical records. Results: The mean annual incidence of physician-diagnosed acute upper respiratory infections (J00-J06 according to ICD-10A) among younger school-age children was between 25.1 and 71.3% per school. A significant correlation was found between vanadium concentration and the number of episodes of acute upper respiratory infections during each study year from 2016 to 2020. The lowest was r = 0.67 (p = 0.024), and the highest was r = 0.82 (p = 0.002). The concentration of vanadium in the samples of dust aggregates varied from 12.7 to 52.1 parts per million (ppm). No significant correlations between the other trace elements and the incidence of upper respiratory infections were found, which could be caused by a small number of study schools and relatively low concentrations of other heavy metals found in the samples of indoor dust aggregates. Conclusion: A significant and replicable correlation was found between the concentration of vanadium in the samples of natural dust aggregates collected in primary schools and the incidence of acute upper respiratory infections in children. Monitoring the concentration of heavy metals in the indoor environment can be an important instrument for the prevention and control of respiratory morbidity in children.

On the shapes of deep slopes of radiocesium vertical profiles in lake sediments.

The shapes of the deep slope (below the maximum values) of the vertical profiles of radiocesium activity concentrations in the sediment samples taken in 2003-2012 in the Lakes Juodis, Tapeliai and Red lake were studied. The Gaussian shape of the deep slope indicates the migration of radiocesium into the depths of the sediments, and this process is significantly enhanced in some places due to bioturbation caused by tench preparing for hibernation. The exponential shape of the deep slope is typical for sediments in which in winter, in the presence of an ice cover on the lake, thermodynamic mixing occurs in the surface layer caused by the effects of pore water buoyancy. In these sediments, radiocesium dissolved in the pore fluid migrates upwards into the near-bottom water, becoming a source of secondary pollution of the water column. In winter, the presence of such a process is easily determined by the emergence of a layered structure of the water column in the lake and the temperatures of the near-bottom waters exceeding 4 °C. In this case, each layer is characterized by constant standard water parameters (temperature, conductivity, concentrations of oxygen, and trace elements). Complex forms of the deep slope of the vertical profile of radiocesium activity concentrations, combining elements of the exponential and Gaussian forms, indicate the episodic presence of both migration mechanisms. A method is proposed for identifying sediments that are a source of secondary pollution of lake waters by estimating the differences between the normalized logarithms of the radiocesium activity concentrations of the deep slopes (below the maximum concentrations) of its vertical profiles in the sediments of the studied samples and the sample of the carbonate barrier sediments, which were discovered in the shallow part of Lake Juodis in 2003.

On the additional risk for human health in the use of sandblasting of building walls.

In 2021, concentrations of heavy metals (Ba, Cr, Fe, Mn, Pb, Ru, Sr, Zn, Zr) and radiocesium (137Cs) were measured in 13 locations in Vilnius in surface samples of walls and facades of buildings built of yellow bricks in order to evaluate possible aerosol air pollution due to sandblasting. The activity concentrations of 137Cs appeared there as a result of global fallout and precipitation of the products of the accident at the Chernobyl Nuclear Power Plant, and the concentration of Pb, as a component of road transport emissions. Other trace elements turned out to be impurities in the material of yellow bricks. In spring 2018, sandblasting of the walls of the building adjacent to the school led to the long-term significant aerosol contamination of school premises (up to 660 µg/m3). Due to sandblasting, the surface of the school sport yard was covered with a thin layer of scraped particles, which were transported by gusts of wind into the school premises. Sandblasting of walls and facades can also be a source of aerosols with 137Cs activity concentrations reaching ~ 40 Bq/kg and Pb - up to 98 ppm. Estimates show that along with 137Cs, the formation of aerosols with activity concentrations of 239, 240Pu reaching 1.6 Bq/kg is possible. Isotopes of 239, 240Pu are analogues of calcium and, when ingested, are deposited in the bones. The ingress of radioactive aerosols into the respiratory tract, especially of children of primary school age, creates additional risks of malignant diseases.

Analysis of the vertical distribution of 137Cs and 239,240Pu in waterlogged and non-boggy soils by the sequential extraction method.

Mobile capabilities of 137Cs, 239,240Pu and some stable element physicochemical forms were studied in soil layers at a depth of 6-8 cm (maximum concentrations of radionuclides) of non-boggy and waterlogged soil cores sampled on the shores of Lake Bedugnis (Lithuania). Soil samples were acidic with small amount of clay (muscovite). The radionuclide activity concentrations were about 2.5 times higher in non-boggy soil. It was explained by different conditions of deposition of radioactive fallout at these sampling sites and density of the soil samples. The value of the exchangeable fraction of radionuclides is shown to be an indicator of their migration capabilities in the soil. Under anaerobic conditions in waterlogged soil (stagnant pore water conditions) and due to the presence of clay admixture, ∼90% of 137Cs was concentrated in the residual fraction and its mobility was low. 239,240Pu was concentrated mainly in organic matter with rather large exchangeable fractions (∼9.6-∼13.9%). Under oxidizing conditions in non-boggy soil (dynamic pore water conditions in the case of rain), 239,240Pu was mostly concentrated in the oxide fraction. Its exchangeable fractions were less than those in waterlogged soil and, respectively, its mobility was lower. In non-boggy soils, exchangeable fractions of 137Cs were large and varied in the range of 10.1-12.2%, which indicated its high mobility. In the case, 137Cs adsorption by clay materials was reduced and its residual fraction did not exceed 71.3%. The obtained data show that in the area of Lake Bedugnis, the migration capabilities of 137Cs and 239,240Pu change in antiphase.

Impact of soil organic matter on Pu migration in five Lithuanian surface soils.

Pu distribution coefficient Kd variation was experimentally determined and examined in natural soil samples considering the type of soil, particle size, pH, the concentration of macroelements and organic matter content. This research was carried out with sand, silty sand, peat, clayey sand and clayey loam samples by applying 236Pu tracer in flow-through column tests. Due to relatively short contact time of 0.5-40 h the tests are considered as have not reached equilibrium state and represent the fast-moving contaminants retardation processes closer to field conditions. Every soil sample was fractionated into two particle size fractions: ≤0.25 mm and 0.25 ÷ 0.5 mm. Analysis revealed that Kd of Pu is higher for the smaller soil particle fraction (≤0.25 mm). The experimental study with 1.6, 4, 6 and 9 pH tracer solution revealed a tendency of elevated Kd when 4 pH and 6 pH solutions were applied, but obtained Kd values were not correlated with initial soil pH due to high buffering capacity of soils. This study shows a very significant influence (r = 0.98) of organic matter content on the Pu distribution coefficient. The Kd of Pu for the fine fraction of peat soil with high organic matter content (67%) reached maximum values of 6597 L/kg and 6200 L/kg when tracer solution was applied of pH = 4 and pH = 6, respectively. In comparison, the minimum Kd value of 3.9 L/kg was obtained for the coarse silty sand fraction with the lowest organic matter content of 1.3% at tracer pH = 1.6. A statistically reliable high correlations of r = 0.95 and 0.94 were also observed between Kd and specific soil elements Mg and Pb content in soils, respectively. The content of Fe in soils was significantly correlated (r = 0.67) with the Kd values of plutonium as well. However, the organic matter content in soils appeared to be the governing factor determining good correlations and causing the highest Kd of Pu values.

Global Alliance against Chronic Respiratory Diseases demonstration project: aerosol pollution and its seasonal peculiarities in primary schools of Vilnius.

BACKGROUND: The growing public health concern caused by non-communicable diseases in urban surroundings cannot be solved by health care alone; therefore a multidisciplinary approach is mandatory. This study aimed to evaluate the airborne aerosol pollution level in primary schools as possible factor influencing origin and course of the diseases in children. METHODS: Seasonal aerosol particle number concentration (PNC) and mass concentration (PMC) were studied in the randomly selected eleven primary schools in the Lithuanian capital, Vilnius, as model of a middle-size Eastern European city. Total PNC in the size range from 0.01 to >1.0 µm in diameter was measured using a condensation particle counter. Using an optical particle sizer, PNC was measured and PMC estimated for particles from 0.3 to 10.0 µm. A descriptive statistics was used to estimate the aerosol pollution levels. RESULTS: During all seasons, local cafeterias in the absence of ventilation were the main sources of the elevated levels of indoor PMC and PNC (up to 97,500 particles/cm). The other sources of airborne particulates were the children's activity during the lesson breaks with PMC up to 586 µg/m. Soft furniture, carpets in the classrooms and corridors were responsible for PMC up to 200 µg/m. Outdoor aerosol pollution (up to 18,170 particles/cm) was higher for schools in city center. Elevated air pollution in classrooms also resulted from intermittent sources, such as construction work during classes (200-1000 µg/m) and petrol-powered lawn trimmers (up to 66,400 particles/cm). CONCLUSION: The results of our survey show that even in a relatively low polluted region of Eastern Europe there are big differences in aerosol pollution within middle-sized city. Additional efforts are needed to improve air quality in schools: more frequent wet cleaning, monitoring the operation of ventilation systems, a ban on construction works during school year, on a use of sandblasting mechanisms in the neighborhood of schools.

On the seasonal aerosol pollution levels and its sources in some primary schools in Vilnius, Lithuania.

Aerosol particle number (PNC) and mass concentrations (PMC) were studied in 11 primary schools during the 2017-2018 school years (from September to May) in Vilnius, Lithuania, with the aim to evaluate the main aerosol pollution sources and its levels. Expeditious information on the total aerosol particle concentration over the full range of sizes (from 0.01 to > 1 µm) was estimated using a condensation particle counter (CPC). Particle number and mass concentrations in the size range of 0.3-10 µm were measured and estimated using an optical particle sizer (OPS). The use of aerosol particle size spectra (OPS) in school lodgements facilitated the identification of the main sources of indoor air pollution. The main sources responsible for the elevated levels of indoor PN and PM aerosol concentrations were determined: local canteens in the absence of ventilation (particle concentrations up to 97,500 part/cm3 (CPC)), the school-grader activity during the lesson breaks (275-586 µg/m3), soft furniture and carpets in the classrooms and corridors (~ 200 µg/m3), and in some cases (city center) elevated outdoor aerosol pollution levels (16800-18,170 part/cm3). Elevated aerosol pollution levels were also due to the occasional sources: construction works during lessons (200-1000 µg/m3), scraping the exterior walls of buildings near schools (up to 1600 µg/m3), and the use of petrol-powered trimmers during cutting of green plantings (22500-66,400 part/cm3 (CPC)).

Experimental and modelling studies of radiocesium sorption/desorption processes in the fixed-bed moss column.

The experimental and modelling studies of the fixed-bed column filled with inanimate mosses Ptilium crista-castrensis containing background levels of 137Cs, flushed with the distilled water are presented. Fitting of the experimental results by Langmuir and Freundlich sorption models gave significant deviations. A more sophisticated two kinetic site model created for the case of non-equilibrium transport of the radiocesium solute through porous media was more suitable to describe the experimental data. It has been shown that theoretically the two site sorption model can be simplified to the conventional one kinetic site model with time dependent parameters. The radiocesium transport equation included the terms taking into account advection, dispersion and decay. General analytical solution was derived for two types of the border conditions: 1) when a constant flux of the material on the surface layer of the absorbent is known (i.e. a Cauchy type border condition); 2) a border condition with constant initial material concentrations. The mathematical solution was derived using the Laplace transformation method. In such a way, the obtained simulated profile of the radionuclide concentration distribution within the fixed-bed column with inanimate mosses showed the best-fitting to the experimental results.