Comparative study of Cs-137 activity concentration between attic dust and urban soil from Salgotarjan city, Hungary

<p>The <sup>137</sup>Cs (t<sub>1/2</sub> =30 years) is a principal radioisotope that was artificially introduced into the environment through the atmospheric bomb tests took place from the middle of the 1940s to the 1980s and from the major nuclear accidents (i.e., Chernobyl, 1986 and Fukushima, 2011). From the atmosphere, <sup>137</sup>Cs easily adsorbs to particles and it returns to lithosphere (pedosphere) by wet and dry deposition as a radioactive fallout component. Due to the Chernobyl nuclear accident, the released contaminated air mass, containing Cs-137, largely propagated, deposited, and distributed across several European countries in the ambient environment (Balonov et al., 1996). These particles also reached houses (e.g. through open windows, cracks, and vents) in an urban environment and deposited inside resulting in the exposition of the habitants to <sup>137</sup>Cs, especially in areas that are not accessible for a regular cleaning like attics. Following the nuclear accidents, primary attention was drawn to agricultural areas and less attention was paid to urban environments. Accordingly, the goal of this study is to compare the <sup>137</sup>Cs activity in attic dust as undisturbed samples, and urban soils as disturbed environmental materials to determine the <sup>137</sup>Cs distribution in urban environment. </p><p>Attic dust (AD) samples were collected from 14 houses, which were built between 1900 and 1990 14 urban soil (US) samples were collected nearby the houses at a depth of 0-15 cm in Salgótarján, a former industrial city. To obtain a representative local undisturbed soil sample, a forest soil sample was collected from the upwind direction (NW) of the city. To check the <sup>137</sup>Cs content of the local industrial waste material, we also collected fly-ash slag sample from a waste dump.   AD and US samples were analyzed by a well-type HPGe and with an n-type coaxial HPGe detector in a low background iron chamber, respectively.</p><p>Cs-137 activity in the studied AD ranges from 5.51±0.9 to 165.9±3.6 Bq kg<sup>-1, </sup>with a mean value of 75.4±2.5 Bq kg<sup>-1 </sup>(decay corrected in 2016). In contrast, US samples show <sup>137</sup>Cs activity ranging between 2.3±0.4 and 13.6±0.6 Bq kg<sup>-1</sup>.  The brown forest soil sample has elevated <sup>137</sup>Cs activity concentration (18.5<strong>±</strong>0.6 Bq kg<sup>-1</sup>), compared to the urban soils. The fly-ash slags activity is below the detection limit (0.7±0.5 Bq kg<sup>-1</sup>).</p><p>The average <sup>137</sup>Cs activity in AD is ~15 times higher than that of US. This result clearly indicates that attic area provides a protected (hardly or unchanged) environment, therefore physical condition of the dust remains constant in time, and there is a small chance for chemical reaction. Forest soil proves that US were highly disturbed by anthropogenic activity. This is supported by fly-ash slag activity results.  Whereas, <sup>137</sup>Cs activity concentration of the AD samples shows significantly higher than that of the studied soils in Hungary. This confirms again US cannot show the historical atmospheric <sup>137</sup>Cs pollution such as attic dust. A statistically significant relationship (p=0.003, r<sup>2</sup>=0.05) were found between the AD and US samples. Therefore, it can be considered that attic dust remained undisturbed for decades and preserve past record of components of atmospheric pollution.</p><p> </p><p> </p>

Study of metallic trace elements in attic dust from two former industrial cities, Salgótarján and Ózd (Hungary)

<p>Anthropogenic activities such as heavy industries produced, among others, airborne pollutants, which are deposited inside the attic of houses like dust material for decades.  Study of attic dust can be an efficient media to better understand long-term airborne dust contamination and distribution in urban areas.  Ózd (OZD) and Salgótarján (STN) are two former industrial cities in the northeastern part of Hungary and separated by 40 km.  Both cities have exposed contaminants for different time periods and sources such as coal mining, local coal fired power plant, iron/steelworks and glass factories, transportation, etc.</p><p>For this study, 40 attic dust samples from STN and 49 attic dust samples from OZD were collected in houses with attics intact for at least 30 years containing long-term industrial pollution.  The concentrations of 13 metals (Ti, V, Cr, Mn, Fe, Co, Ni Cu, Zn, Ag, Sn, Mo and W) were analyzed with ICP-MS.  Most of these elements are considered potentially toxic elements related to industrial activities.  The main aim of the present study was to compare the concentrations, enrichment factors (EFs) in both cities.  EF of each metal was calculated with the formula: EF = [M/Fe]sample/[M/Fe] background, where (M) metals concentration and Fe was used for normalization, following the suggestion in the literature [1] for industrialized cities.  However, geochemical background values for both cities were taken from STN brown-forest soil.</p><p>The median concentration (mg kg<sup>-1</sup>) of the studied metals for the 40 attic dust samples for STN= Fe(23000), Zn(631), Mn(422), Ti(385), Cu(67.7), Cr(26.9), V(42.0), Ni(29.7), Sn(8.70), Co(7.60), Mo(5.24), W(3.26), and Ag(0.030). Likewise, median concentration (mg kg<sup>-1</sup>) for the 49 attic dust samples for OZD= Fe(48000), Zn(1338), Mn(1249), Ti(230), Cu(104), Cr(55.9), V(42.0), Ni(28.0), Sn(16.2), Co(7.20), Mo(4.68), W(3.64), Ag(0.116).</p><p>The values of median enrichment factor (EF) revealed the following order: STN=(Ti>W>Sn>Cu>Zn>Mo>Ag>Cr>V>Ni>Mn>Co) and OZD=(W>Ti>Sn>Ag>Zn>Cu>Cr>Mo>V>Mn>Ni>Co).  The results for both cities are Ti, W, Sn, Cu, Ag, Zn with enrichment factor (EF)>5, which represent significant or very significant enrichment; Ni, Mn, Co show values of (EF)<2 indicating no enrichment- to minimal enrichment, and Cr has 2<(EF)<5 = moderate enrichment.  Note that V shows moderate enrichment in STN samples and minimal enrichment in OZD samples.  Molybdenum shows significant in STN samples and moderate enrichment in OZD samples.</p><p>The differences between OZD and STN attic dusts show the complexity of two scenarios where concentrations in OZD attic dusts are 1.5 – 4 times higher than STN ones and significant enrichment for Sn, Ag, Zn, Cu, Cr due to probably more intense steelwork activities.</p><p><strong>Keyword: Attic dust, enrichment factor, Salgótarján, Ózd.</strong></p><p><strong>Reference:</strong></p><p>[1] Luo, X. S., Xue, Y., Wang, Y. L., Cang, L., Xu, B., & Ding, J. (2015). Source identification and apportionment of heavy metals in urban soil profiles. Chemosphere, 127, 152–157. https://doi.org/10.1016/j.chemosphere.2015.01.048</p>

ASSESSMENT OF TRACE ELEMENTS BIOAVAILABILITY – INGESTION OF TOXIC ELEMENTS FROM THE ATTIC DUST COLLECTED FROM THE VICINITY OF THE FERRO-NICKEL SMELTER PLANT

The purpose of this study was to establish total and bioavailable contents of chemical elements in attic dust and their distribution in the area of the town of Kavadarci, Republic of Macedonia, and in this way to evaluate the exposure of population to toxic metals in areas with high industrial influences from the ferro-nickel smelter plant. The attic dust is derived predominantly from external sources such as aerosol deposits and soil dusting, and less from household activities. From that reason attic dust could be accepted as a tracer of historical aerosol pollution. All attic dust samples were analyzed for total and bioavailable element contents and their distribution in studied area. Several extraction agents recognized as representative for elements bioa-vailability assessment were applied to attic dust samples under investigations – phosphate buffer solutions that simulate human blood, for the simulation of lung inhalation carbonate buffer was used and 0.1 mol l–1 HCl solution to simulate stomach ingestion. A total of 18 elements (Ag, Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe K, Mg, Mn, Ni, Pb, Sr and Zn) were determined by atomic emission spectrometry with inductively coupled plas-ma (AES-ICP). The obtained results showed relatively high proportion of toxic elements bioavailability in the attic dusts samples from sites close to the metallurgical activities (Cr, Cu, Mn, Ni, Pb and Zn), most probably due to the small size and high reactivity of the particles of attic dust. As might be expected the highest leacha-ble amounts of toxic elements were found for Ni, Co, Cr and Pb from attic dust in the extraction solution of HCl (0.1 mol l–1 HCl) compared with the other 3 extraction media. Discussion on trace elements mobility and bioavailability related to environmental pollution and effects on human health are presented.