(Table 1) Chlorophyll a content and microalgae abundance and biovolume in pack ice in the Bellingshausen Sea

Pack ice in the Bellingshausen Sea contained moderate to high stocks of microalgal biomass (3-10 mg Chl a/m**2) spanning the range of general sea-ice microalgal microhabitats (e.g., bottom, interior and surface) during the International Polar Year (IPY) Sea Ice Mass Balance in the Antarctic (SIMBA) studies. Measurements of irradiance above and beneath the ice as well as optical properties of the microalgae therein demonstrated that absorption of photosynthetically active radiation (PAR) by particulates (microalgae and detritus) had a substantial influence on attenuation of PAR and irradiance transmission in areas with moderate snow covers (0.2-0.3 m) and more moderate effects in areas with low snow cover. Particulates contributed an estimated 25 to 90% of the attenuation coefficients for the first-year sea ice at wavelengths less than 500 nm. Strong ultraviolet radiation (UVR) absorption by particulates was prevalent in the ice habitats where solar radiation was highest - with absorption coefficients by ice algae often being as large as that of the sea ice. Strong UVR-absorption features were associated with an abundance of dinoflagellates and a general lack of diatoms - perhaps suggesting UVR may be influencing the structure of some parts of the sea-ice microbial communities in the pack ice during spring. We also evaluated the time-varying changes in the spectra of under-ice irradiances in the austral spring and showed dynamics associated with changes that could be attributed to coupled changes in the ice thickness (mass balance) and microalgal biomass. All results are indicative of radiation-induced changes in the absorption properties of the pack ice and highlight the non-linear, time-varying, biophysical interactions operating within the Antarctic pack ice ecosystem.

Results from ikaite investigations in the Kara Sea

The authigenic carbonate mineral ikaite is specific of low-temperature high latitude environments. The depletion of ikaite carbon in 13C isotopes in most cases implies a causal relation of ikaite generation with methane geochemistry. In this paper we present new data on ikaite minerals in Holocene sediments sampled along the Yenisei channel at the southern (74°N) and northern (77°N) ends. Stable carbon isotopes of the ikaite crystals were studied in conjunction with the hydrochemistry and isotope geochemistry of the sediments. Pore water and natural gas samples were separated from sediments to describe the methane carbon isotope distribution pattern throughout two sedimentary sequences embedding the ikaite crystals of different isotope composition (-24 per mil and -42 per mil). The biogenic nature of the methane is indicated by 51 C values being as low as -104.4 per mil. In the case of the moderately depleted sample (-24 per mil) from the southern location the small-scale ikaite formation fits best into the concept of a 'closed» sediment system, with a limited diagenetic carbon dioxide source being present. In the second case, formation of highly abundant and isotopically depleted ikaite crystals (-42 per mil) were caused by upwards flux of biogenic methane from below. Contribution of two main carbon sources to the ikaite crystals was estimated by using a isotope-mass balance equation. Organic-derived CO2 constitutes the principal source in both samples, amounting to 50 % of the total carbon of the strongly depleted ikaite crystals (-42 per mil) sampled at the northern end and 83 % for the moderately (-24 per mil) depleted crystals from the southern end. Methane-derived CO2 comes to 42 % for the isotopically light ikaite crystals and to 9% for the isotopically heavy crystals. The importance of sediment lithology and diffusive transport for ikaite formation is emphazied.

Annotated record of the detailed examination of ferromanganese concretions from the Svalbard shelf in the Barents Sea

Ferromanganese concretions from ten stations in the Barents Sea have been analysed for 24 elements. The deposits occur as discoidal and flat concretions and as coatings, in the latter case on lithified or detrital material or as extensive pavements on the Svalbard shelf. The concretions are compositionally similar to Baltic concretions but differ considerably from deep-ocean nodules, particularly in Cu, Ni and Co contents. Statistical analyses reveal distinct correlations between Mn, Na, Ba, Ni and Cu; the Mn-rich coatings showed enrichment of Mo, Zn and possibly Co in a Mn-phase. The iron phase holds high concretions of P and As. Two iron-rich concretions with high contents of P, Ca, Sr, Y, Yb and La were found east and northeast of Spitsbergen Banken, probably indicating upwelling of nutrient-rich, cold polar water along the Svalbard shelf.

Case studies of the effects of a total solar eclipse on weather with varying degrees of cloud cover using a local numerical weather prediction model

The importance of renewable energies for the European electricity market is growing rapidly. This presents transmission grids and the power market in general with new challenges which stem from the higher spatiotemporal variability of power generation. This uncertainty is due to the fact that renewable power production results from weather phenomena, thus making it difficult to plan and control. We present a sensitivity study of a total solar eclipse in central Europe in March. The weather in Germany and Europe was modeled using the German Weather Service's local area models COSMO-DE and COSMO-EU, respectively (http://www.cosmo-model.org/). The simulations were performed with and without considering a solar eclipse for the following 3 situations: 1. An idealized, clear-sky situation for the entire model area (Europe, COSMO-EU) 2. A real weather situation with mostly cloudy skies (Germany, COSMO-DE) 3. A real weather situation with mostly clear skies (Germany, COSMO-DE) The data should help to evaluate the effects of a total solar eclipse on the weather in the planetary boundary layer. The results show that a total solar eclipse has significant effects particularly on the main variables for renewable energy production, such as solar irradiation and temperature near the ground.