The Chukchi Sea fast-ice cover sampled at Barrow is representative of first-year sea ice, with the characteristic temperature and salinity profiles that in turn determine the brine volume fraction (at right, which is below 50 to 70 ppt throughout much of the ice column at the peak of winter). Based on what has been outlined above, this ice would be considered "impermeable". Shown at left, however, is a cross-section through the ice cover with both horizontal layering and vertical channels clearly visible.

While the particulate concentration in this "clean" ice is below 10 mg/l, chlorophyll a as a measure of algal biomass in the ice is observed to increase exponentially to maximum concentrations at the bottom of the ice cover. Bacterial abundances in the upper, cold and otherwise barren ice layers are lower by a factor of 2 as compared to the lowermost, warm and algae-rich layers.

Elson Lagoon in the vicinity of Barrow is a shallow Arctic lagoon that offers us the chance to study and sample sediment-laden sea ice, a phenomenon that is not quite as unusual or uncommon in the Arctic as one might think. While most of the ice properties are comparable with those of Chukchi Sea fast ice (after all, these samples were taken at locations less than 10 km apart with the ice grown under similar meteorological conditions), the particulate content in the upper, "dirty" layers (see ice slab photograph) generally exceeds 10 mg/l and can be as high 150 mg/l or more. The bacterial abundance in this cold, sediment-rich layer is an order of magnitude higher than even the warm, high-chlorophyll layer from the Chukchi Sea. This finding suggests that there might be a linkage between bacterial sustenance (possibly activity?) at very low temperatures and particulate content of sea ice. Furthermore, it is interesting to note that these high bacterial abundances were observed in cold, segregated pore-space ice.