Particulate organic matter elemental analysis, mixed layer, during the K-Azis voyage of the Aurora Australis au1603

Water samples of 1 to 2L from Niskin bottles filled close to the surface, mid mixed layer depth and bottom of the mixed layer were drawn cleanly through a 210um mesh to exclude zooplankton. All samples were filtered as two size fractions, 1.2 to 20um (larger particles excluded by 20um Nitex mesh) and a separate 1.2 to 210um total sample. The filters were 1.2um silver membranes (Sterlitech) 13mm diameter. The samples were preserved by drying at 60C in a dedicated clean oven. Prior to encapsulation, a 5mm diameter subsample was taken for biogenic silica analysis, which is delayed until there has been evaluation of the particle data from the flow cam and UVP. Samples were encapsulated in silver (Sercon sc0037) after acidification and drying. The decarbonated encapsulated POC samples were analysed by elemental analyser at the CSL UTAS by Dr Thomas Rodemann (EA TCD 960C, single point standardisation every 12 samples).  EA detection limit 0.001umol POC. POC and PON are presented as molar units. Blanks were process blanks (seawater) and 7% of the average for the combined data n=177. 1sd=0.12uM.

The ctd casts were all given the prefix K, so K001, K002 etc. Not all stations were sampled due to budget constraints. Niskin is the Niskin bottle number.