Distribution patterns of biogenic components in surface sediments of the Ross Sea and their environmental implications

The Ross Sea shelf is characterized by its highest primary productivity among the Antarctic marginal seas, and is a hotspot for studying ice-ocean-atmosphere interactions and carbon cycle. This study analyzed the contents of biogenic components such as biogenic silica (Opal), carbonate, total organic carbon (TOC), total nitrogen (TN), and organic carbon δ¹³C (δ¹³C_org) in 43 surface sediments collected during the 31st-35th Chinese Antarctic Research Expeditions on the Ross Sea shelf. Cluster analysis and factor analysis were performed on the resulted data in order to obtain their distribution patterns in relation to the environmental settings. Our results show that TOC, TN and Opal are the main variables for factor 1 representing the productivity of the water column. Their contents show high values in the polynyas on the southwest shelf, and on the southeast inner shelf, in contrast to low values in the Cape Adare and outer shelf, interpreted as related to concentrations of dissolved iron in the water. δ¹³C_org is the main variable for factor 2, with higher values in the Terra Nova Bay polynyas and the outer northeast shelf, and lower values in the troughs. The heavier δ¹³C_org is resulted from high primary productivity while the lighter δ¹³C_org mainly reflects terrestrial carbon accumulation from lateral transport. Carbonate is the main variable for factor 3 showing higher contents at Cape Adare and in the Ross Sea polynyas, and lower contents in the troughs and the south-eastern shelf, primarily related to its preservation.