The distribution of zinc, cadmium, copper and iron in seawater of the Iceland-Faroe Ridge area

During the International ICES Expedition "Overflow '73" a total of 174 samples from 18 stations were collected by R. V. "Meteor" in the waters of the Iceland-Faroe Ridge area. They were filtered on board ship (through 0.4 mym "Nuclepore" filters), then stored in 500 cm**3 quartz bottles (at -20 °C) and analyzed in air-filtered laboratories on land for zinc and cadmium by means of the differential pulse anodic stripping voltammetry technique and copper and iron by flameless atomic absorption spectrometry. The overall averages of 1.9 myg Zn l**-1, 0.07 myg Cd l**-1, 0.5 myg Cu l**-1 and 0.9 myg Fe l**-1 are in good agreement with recent "baseline" studies of open-ocean waters. The mixture of low salinity water masses from the North Iceland Shelf/Arctic Intermediate Waters seem to maintain distinctly lower concentration of Cd, Cu and Fe than the waters from the North Atlantic and the Norwegian Sea where quite similar mean values are found. There is only little evidence for the assumption that overflow events on the ridge are influencing the concentrations of dissolved metals in the near-bottom layers.

Temperature, salinity and ikaite crystal characteristics in snow, slush and sea ice during R/V Lance cruise in April-May 2011

We identified ikaite crystals (CaCO3 · 6H2O) and examined their shape and size distribution in first-year Arctic pack ice, overlying snow and slush layers during the spring melt onset north of Svalbard. Additional measurements of total alkalinity (TA) were made for melted snow and sea-ice samples. Ikaite crystals were mainly found in the bottom of the snowpack, in slush and the surface layers of the sea ice where the temperature was generally lower and salinity higher than in the ice below. Image analysis showed that ikaite crystals were characterized by a roughly elliptical shape and a maximum caliper diameter of 201.0±115.9 µm (n = 918). Since the ice-melting season had already started, ikaite crystals may already have begun to dissolve, which might explain the lack of a relationship between ikaite crystal size and sea-ice parameters (temperature, salinity, and thickness of snow and ice). Comparisons of salinity and TA profiles for melted ice samples suggest that the precipitation/dissolution of ikaite crystals occurred at the top of the sea ice and the bottom of the snowpack during ice formation/melting processes.