Stratification and the distribution of phytoplankton, nutrients, inorganic carbon, and sulfur in the surface waters of Weddell Sea leads

The distribution (fine resolution depth profiles) of major nutrients, chlorophyll-a, organic compounds, and phytoplankton (biomass and numbers) was examined in lead water in pack ice of the Weddell Sea. Samples were taken by pulling water into a syringe from a series of depths from 0.002 to 4 m. While concentrations of compounds of interest remained constant in the water column, an enhanced depletion of nutrients (ammonium, nitrate, silicate, and inorganic carbon) occurred above the pycnocline at 0.1 m. Coinciding with this depletion was an increase of organic matter and chlorophyll. The change in carbon isotopic composition showed that an enhanced primary production occurred at the sea surface. Cell counts and nutrient disappearance ratios suggest that primary production was dominated by diatoms. These results show that the sea surface can have different chemical characteristics than the deeper water column.