Nutrient supply, uptake and cycling underpin high primary productivity over the continental shelf of the west Antarctic Peninsula (WAP). Here we use a suite of biogeochemical and isotopic data collected over five years in northern Marguerite Bay to examine these macronutrient dynamics and their controlling biological and physical processes in the WAP coastal ocean. We show pronounced nutrient drawdown over the summer months by primary production which drives a net seasonal nitrate uptake of 1.83 mol N m-2 yr-1, equivalent to net carbon uptake of 146 g C m-2 yr-1. High primary production fuelled primarily by deep-sourced macronutrients is diatom-dominated, but non-siliceous phytoplankton also play a role. Strong nutrient drawdown in the uppermost surface ocean has the potential to cause transient nitrogen limitation before nutrient resupply and/or regeneration. Interannual variability in nutrient utilisation corresponds to winter sea ice duration and the degree of upper ocean mixing, implying susceptibility to physical climate change. The nitrogen isotope composition of nitrate (δ15NNO3) shows a utilisation signal during the growing seasons with a community-level net isotope effect of 4.19 ± 0.29‰. We also observe significant deviation of our data from modelled and observed utilisation trends, and argue that this is driven primarily by water column nitrification and meltwater dilution of surface nitrate. This study is important because it provides a detailed description of the nutrient biogeochemistry underlying high primary productivity at the WAP, and shows that surface ocean nutrient inventories in the Antarctic sea ice zone can be affected by intense recycling in the water column, meltwater dilution and sea ice processes, in addition to utilisation in the upper ocean.
View post tag: News by topic View post tag: Naval HMS Edinburgh Leaves Portsmouth, UK Share this article View post tag: Navy Training & Education On a warm and sunny bank holiday morning, HMS Edinburgh slipped her lines from Portsmouth and began her final voyage around the UK. This marks a milestone in her 30 year long career serving in the Royal Navy, in which she has sailed around the world on operations, clocking up over 600,000 miles.Whilst on the tour around the UK, HMS Edinburgh will be taking part in the Battle of the Atlantic commemorations both in London and Liverpool. She will be joining HMS Illustrious and HMS Blythe in London where they will provide a platform to welcome onboard members of the public and will host a number of VIPs and dignitaries during this high profile visit.Whilst transiting from Portsmouth to London, HMS Edinburgh welcomed some friends and families of the Ship’s Company onboard giving them the opportunity to experience life on board an operational warship for a couple of days at sea.Friends and family members experienced the Ship leaving Portsmouth for the final time and were able to witness various exercises being conducted, including the chance to take part in Small Arms Firing At Sea (SAFAS) and drive the ship for a Man Overboard Exercise.HMS Edinburgh is due to visit Edinburgh, her affiliated home city, after leaving London following which she will transit to Liverpool before making her final entry into Portsmouth.She will be escorted through the Solent by HMS Diamond, one of the new Type 45 Destroyers built to replace HMS Edinburgh and her sister ships.[mappress]Press Release, May 7, 2013; Image: Royal Navy View post tag: Defense View post tag: Edinburgh View post tag: Leaves Back to overview,Home naval-today HMS Edinburgh Leaves Portsmouth, UK View post tag: Defence May 7, 2013 View post tag: Portsmouth View post tag: UK View post tag: HMS