Abstract:

Particulate organic carbon (POC) is an important material and energy source for the marine food chain. Because of its close relationship with life processes and primary productivity, its distribution can effectively provide information on the biogeochemical environment. During the 33rd CHINARE that took place between December 2016 and January 2017, suspended particulate matter samples were collected from the ocean adjacent to the Antarctic Peninsula to study POC distribution and factors influencing POC distribution. In the Scotia Sea, POC concentrations were between 7.44 and 193.52 μg·L⁻¹, with a mean value of 48.84±35.09 μg·L⁻¹; over South Scotia Ridge, concentrations were between 9.13 and 62.17 μg·L⁻¹, with a mean value of 29.76±14.12 μg·L⁻¹; in Powell Basin, concentrations were between 5.87 and 270.72 μg·L⁻¹, with a mean value of 48.57±38.92 μg·L⁻¹. In surface waters, high concentrations were found in Scotia Sea and Powell Basin while low concentrations were found over South Scotia Ridge; these results are consistent with variations in chlorophyll-a concentration, but are opposite to those in nutrient concentration. Concentrations of POC decreased with depth. In Powell Basin and Scotia Sea, the highest POC concentrations were found between the surface and a depth of 25 m. Results from principal component analysis show that photosynthetic phytoplankton is the main source of POC in the study area. Concentrations of POC were affected by temperature, water mass mixing and melting sea ice. Proportions of non-living POC were low over South Scotia Ridge; they were high in Scotia Sea and Powell Basin because of high krill biomass, sea ice debris and input from land-based sources.

Key words: ocean adjacent to Antarctic Peninsula, Particulate Organic Carbon (POC), Chlorophyll-a, nutrients, sea ice