Glacial interglacial variations in the natural iron fertilization during the low sea ice periods along the eastern continental margin of Antarctica

Abstract

The Southern Ocean can sequester atmospheric CO2 through biological pumps, though its driving factors are debated. The Southern Ocean is nutrient-limited and modern productivity is regulated by natural iron fertilization from micronutrient influx through dust, regeneration, and Antarctic glaciers and sea ice melting (ice melt). While the long-term utilization of micronutrients through oceanic productivity is unknown. The productivity along the eastern Antarctic continental margin was low during the last glacial period, and gradual increase through the deglacial to Late Holocene, marked by distinct productivity peaks. The micronutrients also varied in a similar pattern, as minimal glacial influx and increase towards the Holocene may cause productivity peaks. Therefore the enhanced productivity and micronutrient influx periods are considered as the iron fertilization periods. The increase in productivity peaks declined during this period is declined within ~1.5 kyr, mostly due to the Ekman transport and sea ice formation. Along with ice melt, The independent weathering pattern that responds with glacial- interglacial ice volume changes suggest the source of micronutrients are other than terrigenous. Variations in the shelf interaction of ACC can influence the water column nutrient stock significantly, while its utilization occurs during minimal Albedo periods with ice (low sea ice and glaciers) released micronutrients periods. Therefore, enhanced natural iron fertilization periods are implicated as are considered as low sea ice minimum periods, at ~7.5 kyr BP, ~5.5 kyr BP, ~4 kyr BP, ~ 2.5 kyr BP, and ~0.5 kyr BP, likely formed due to the mutual effects of atmospheric and oceanographic factors mostly driven by the high amplitude regional temperature variability during the mid to late Holocene.