Solar and wastewater effects on zooplankton communities of the Imandra Lake (Kola Peninsula, Russia), 1990 to 2003

Both heliophysical and anthropogenic (wastewater) effects on zooplankton biomass and abundance of the Imandra Lake (the largest subarctic lake at Kola Peninsula, Russia) were investigated during the 1990 - 2003 period. We used different indexes of solar activity (sunspot numbers and UV- radiation values) as heliophysical factors. Information about UV- radiation values was derived from satellite data. As a parameter of anthropogenic pollution we used the information about wastewaters input in Imandra Lake by copper-nickel (Severonikel plant) enterprise and apatite-nepheline industry (AO Apatit). Besides we used the direct measurements of concentrations of the most important pollutants (Al, Ni, Cu) and biogenic components (N and P) in the Imandra Lake. It was shown that the correlation between heliophysical factors and zooplankton biomass and abundance was high and significant (r= 0.7- 0.8), and it was not significant between waste waters input volume and zooplankton productivity. According to the results obtained the main factor influencing zooplankton bioproductivity is solar UV-B radiation due to its damage effects. In addition for middle latitude Krasnoye Lake (Karelia, Russia; 1964 to 1984) and Lake Michigan (USA, 1984 to 1990) data we found nearly the same effect- anticorrelation between UV radiation level and zooplankton bioproductivity, but unfortunately the significance level was not sufficient. However, the effect at middle latitudes was some lower than at high-latitude Imandra Lake. Such discrepancy seemed to be associated with different day duration at high and middle latitudes. Our results seem to prove that solar forcing (mainly UV-B radiation) is significant factor governing zooplankton bioproductivity in subarctic lakes even in such polluted one like Imandra Lake

Enhancement of stratospheric aerosols after solar proton event.

The lidar measurements at Verhnetulomski observatory (68.6¡N, 31.8¡E) at Kola peninsula detected a considerable increase of stratospheric aerosol concentration after the solar proton event of GLE (ground level event) type on the 16/02/84. This increase was located at precisely the same altitude range where the energetic solar protons lost their energy in the atmosphere. The aerosol layer formed precipitated quickly (1Ð2 km per day) during 18, 19, and 20 February 1984, and the increase of R(H) (backscattering ratio) at 17 km altitude reached 40% on 20/02/84. We present the model calculation of CN (condensation nuclei) altitude distribution on the basis of an ion-nucleation mechanism, taking into account the experimental energy distribution of incident solar protons. The meteorological situation during the event was also investigated