Correlations between 7Be, 210Pb, dust and PM10 concentrations in relation to meteorological conditions in northern Poland in 1998-2018.

ABSTRACT

Analysis of a twenty-year (1998-2018) data series on 7Be concentrations in weekly collected aerosol samples in northern Poland showed a clear pattern of seasonal changes in 7Be with a maximum in the summer period associated with the most intensive thermal convection and vertical mixing. Activity concentrations of 7Be ranged from 480 µBq m-3 to 9370 µBq m-3. A strong relationship has been shown between 7Be concentrations observed in years and the activity of the Sun related to the sunspot number. Activity concentrations of 210Pb in aerosol ranged from 17 µBq m-3 to 1490 µBq m-3 with maximum occurring in the winter. The difference in the seasonal pattern in 7Be and 210Pb concentrations were directly related to the different sources of both isotopes, as an additional source of 210Pb was the products of combustion during the heating season. Similar pattern with maximum concentrations in winter was observed for PM10, as the main source is the same as in the case 210Pb. A content of PM10 was in the range from 6.5 to 81.7 µg m-3. A statistically significant correlation between both isotopes occurs. At the same time, 7Be, 210Pb and PM10 are visibly related to the dust concentrations ranged from 7.3 µg m-3 in winter to 134.8 µg m-3 in spring. Statistical analysis carried out with simple regression model, stepwise multiple regression, and Random Forest models showed that the sunspots number, air temperature and sunshine duration have the most substantial impact on transport, and hence the concentration of 7Be in the surface layer of the atmosphere. The increase in relative humidity and precipitation and higher wind speed have a statistically significant effect on the reduction of 7Be concentrations in surface air.