Characteristics and aldehyde concentrations of diamond dust events near Barrow, Alaska

Diamond dust (DD) refers to tiny ice crystals that form frequently in the Polar troposphere under clear sky conditions. They provide surfaces for chemical reactions and scatter light. We have measured the specific surface area (SSA) of DD at Barrow in March-April 2009. We have also measured its chemical composition in mineral and organic ions, dissolved organic carbon (DOC), aldehydes, H2O2, and the absorption spectra of water-soluble chromophores. Mercury concentrations were also measured in spring 2006, when conditions were similar. The SSA of DD ranges from 79.9 to 223 m**2/kg . The calculated ice surface area in the atmosphere reaches 11000 (±70%) µm**2/cm**3, much higher than the aerosol surface area. However, the impact of DD on the downwelling and upwelling light fluxes in the UV and visible is negligible. The composition of DD is markedly different from that of snow on the surface. Its concentrations in mineral ions are much lower, and its overall composition is acidic. Its concentrations in aldehydes, DOC, H2O2 and mercury are much higher than in surface snows. Our interpretation is that DOC from the oceanic surface microlayer, coming from open leads in the ice off of Barrow, is taken up by DD. Active chemistry in the atmosphere takes place on DD crystal surfaces, explaining its high concentrations in aldehydes and mercury. After deposition, active photochemistry modifies DD composition, as seen from the modifications in its absorption spectra and aldehyde and H2O2 content. This probably leads to the emissions of reactive species to the atmosphere.

(Table 1) Zoobenthos from the gas-hydrate seep area near the Paramushir Island and its chemical composition

Distributions of Mn, Fe, Cu, Cd, Cr, Co and Ni in sea water are investigated (42 samples, dissolved and particulate forms) in the vicinity of the underwater gas vent field on the northwestern slope of the Paramushir Island. While regular background distributions of the elements occur in the shore zone, there is a column of elevated concentrations of particulate matter, particulate Mn, and dissolved Mn, Fe, Cu, Cd, Cr, Co and Ni that coincides with location of the gas plume. This column can be traced as high as 780 m above the bottom. High metal concentrations in water of the plume are attributable to physico-chemical concentration at the phase interface; the source of elevated mineral concentrations is obviously flux of dissolved minerals from interstitial waters, which extends to considerable distances in vertical direction.

(Table 1) Carbon pools in different vegetation components in grazed and ungrazed plots near Ny-Ålesund, Spitzbergen

The carbon (C) sink strength of arctic tundra is under pressure from increasing populations of arctic breeding geese. In this study we examined how CO2 and CH4 fluxes, plant biomass and soil C responded to the removal of vertebrate herbivores in a high arctic wet moss meadow that has been intensively used by barnacle geese (Branta leucopsis) for ca. 20 years. We used 4 and 9 years old grazing exclosures to investigate the potential for recovery of ecosystem function during the growing season (July 2007). The results show greater above- and below-ground vascular plant biomass within the grazing exclosures with graminoid biomass being most responsive to the removal of herbivory whilst moss biomass remained unchanged. The changes in biomass switched the system from net emission to net uptake of CO2 (0.47 and -0.77 µmol/m**2/s in grazed and exclosure plots, respectively) during the growing season and doubled the C storage in live biomass. In contrast, the treatment had no impact on the CH4 fluxes, the total litter C pool or the soil C concentration. The rapid recovery of the above ground biomass and CO2 fluxes demonstrates the plasticity of this high arctic ecosystem in terms of response to changing herbivore pressure.

(Table 1) Grain size parameters of intertidal channel sand bars near Sylt, North-Frisian Wadden Sea

The aim of the present study is to investigate directional asymmetric properties and internal structures of the bedforms on the intertidal sand bars in comparison with the migration problems of the sand bodies developed in the channel systems of the tidal basin off the west coast of Schleswig-Holstein. The tidal channel sand bodies studied have 'V'-shaped outlines and are asymmetric in cross-section. Based on such knowledge it was hoped to understand and find possible factors for application to recent and ancient tidal depositional environments. The V-shaped intertidal channel sand bodies developed in the tidal environments between Sylt and Föhr Island are constantly migrating sand bars. The migration directions are in good agreement with the resultant vector mean directions of internal cross-stratification structures of asymmetric sedimentary bedforms. Finally, it is shown that the orientation of the apex of V-shaped sand bar as an equilibrium form alone can not indicate the migration direction, but that the orientation of the resultant vector mean of internal structures of sedimentary bedforms does indicate the migration direction. Based on the analyses of textural parameters of the migrating intertidal bar sands, it seems that sands of typical intertidal sand bars are negatively skewed and well sorted. The high rounding of quarz sand grains of these tidal channel sand bars seems to be an additional characteristical criterion for tidal depositional environments, as also indicated by Balazs and Klein (1972).

Processed CO2/O2 Float data from 4 deployments near Cape Verde Island (11/2010 - 06/2011)

In recent years, profiling floats, which form the basis of the successful international Argo observatory, are also being considered as platforms for marine biogeochemical research. This study showcases the utility of floats as a novel tool for combined gas measurements of CO2 partial pressure (pCO2) and O2. These float prototypes were equipped with a small-sized and submersible pCO2 sensor and an optode O2 sensor for highresolution measurements in the surface ocean layer. Four consecutive deployments were carried out during November 2010 and June 2011 near the Cape Verde Ocean Observatory (CVOO) in the eastern tropical North Atlantic. The profiling float performed upcasts every 31 h while measuring pCO2, O2, salinity, temperature, and hydrostatic pressure in the upper 200 m of the water column. To maintain accuracy, regular pCO2 sensor zeroings at depth and surface, as well as optode measurements in air, were performed for each profile. Through the application of data processing procedures (e.g., time-lag correction), accuracies of floatborne pCO2 measurements were greatly improved (10-15 µatm for the water column and 5 µatm for surface measurements). O2 measurements yielded an accuracy of 2 µmol/kg. First results of this pilot study show the possibility of using profiling floats as a platform for detailed and unattended observations of the marine carbon and oxygen cycle dynamics.