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A new geostatistical tool for the analysis of the geographical variability of the indoor radon activity

Loffredo Filomena, Scala Antonio, Adinolfi Guido Maria, Savino Federica, Quarto Maria

Nukleonika

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2020

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Vol. 65, No. 2

99--104

EN

The population is continuously exposed to a background level of ionizing radiation due to the natural radioactivity and, in particular, with radon (222Rn). Radon gas has been classified as the second leading cause of lung cancer after tobacco smoke [1]. In the confined environment, radon concentration can reach harmful level and vary accordingly to many factors. Since the primary source of radon in dwellings is the subsurface, the risk assessment and reduction cannot disregard the identification of the local geology and the environmental predisposing factors. In this article, we propose a new methodology, based on the computation of the Gini coefficients at different spatial scales, to estimate the spatial correlation and the geographical variability of radon concentrations. This variability can be interpreted as a signature of the different subsurface geological conditions. The Gini coefficient computation is a statistical tool widely used to determine the degree of inhomogeneity of different kinds of distributions. We generated several simulated radon distributions, and the proposed tool has been validated by comparing the variograms based on the semi-variance computation with those ones based on the Gini coefficient. The Gini coefficient variogram is shown to be a good estimator of the inhomogeneity degree of radon concentration. Indeed, it allows to better constrain the critical distance below which the radon geological source can be considered as uniform at least for the investigated length scales of variability; it also better discriminates the fluctuations due to the environmental predisposing factors from those ones due to the random spatially uncorrelated noise.

2

Scots pine forests of the Vaccino-Piceetea class in Europe : forest sites studied

Solon J.

Polish Journal of Ecology

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2003

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Vol. 51, nr 4

421-439

EN

The paper presents: a) the general differentiation of the pine forests of Europe, and b) the floristic differentiation of the study sites, located along the transect stretching between 50 stopni 28 minut and 70 stopni 09 minut N, as well as c) the relations between the geographical location and the climatic characteristics on the hand, and the selected features of the richness and species diversity of the herb layer on the other. One can observe a dependence (p<0.05) between the temperature and latitude on the one hand, and the number of species from some groups on the other. For the vascular plants, the indicators of linear correlation amount to, respectively, 0.64 and -0.63 (the number of the vascular species of the herb layerr increases with the warming of climate and the movement towards the South), and for the numbers of lichen species: -0.81 and 0.78 (the dependencies have the opposite directions to the previous ones). The variability of the relative shares of the particular species groups is correlated with geographical location and climatic variables. Three basic patterns of spatial variability can in this context be identified. The first of these is represented by the share of the lignified chamaephytes (dwarfshrubs). In accordance with this pattern, the minimum shares are observed at the latitudes of Lithuania, Latvia, and Estonia. The second pattern of variability is represented by the shares of hemicryptophytes. In accordance with this pattern the maximum shares are observed between 53 stopnie and 56 stopni N. The third pattern of variability is represented, in particular, by the share of the evergreen species which is proporrtional to the latitude.

3

Ground vegetation carbon and its relation to climate and species richness

Solon J., Roo-Zielińska E.

Polish Journal of Ecology

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2003

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Vol. 51, nr 4

513-527

EN

Ten pine forest sites located along the transect between 50 stopni 28 minut and 70 stopni 09 minut N were studied. The purposes of the present paper are: 1) to determine the volume of the organic carbon pool in selected layers of the analysed forest ecosystems (shrubs, herb layer, mosses and lichens, litter, and the humus horizon of the soil); and 2) to elaborate the correlation-based prediction models relating the organic carbon pools in these layers with the selected variables characterising the climate and the species richness of the pine forests. The results indicate a clear horizontal heterogeneity of the ground layer in the pine forests considered. This is reflected, in particular, through the differentiation of the carbon pool in particular places within the ecosystem. Thereis a distict geographical variability in the carbon pool among the sites in particular layers, with the average annual and January temperatures having the largest influence on this variability. However, in different cases there are different combinations of the factors describing these relations in the best way. The relations between the carbon pool and the species richness of the sites along the transect show that either the minimal carbon pool occurs at sites of an average species richness, or there is no relation between these variables. The analysis implies that there are two points of the transect at which various characteristics of the system undergo an abrupt shift. The first of them is equivalent to the passage of the annual +1 stopień C isotherm, while the second at approximately 5-6 stopni C. There is the possibility that these regularities occur within the entire range of the pine forests.