RESUMEN
The historical climate variability in East Antarctica inferred from ice cores remains under debate owing to the vastness and complexity of the region. This study evaluates the potential climate variabilities in the Styx-M ice core records (δ18O, d-excess, and snow accumulation) from northern Victoria Land adjacent to the Ross Sea sector of East Antarctica during 1979-2014. Results show that the primary moisture source in this area is the Pacific Ocean sector. Although the annual mean δ18O values was limited to directly indicate the temperature changes, a weak relevance between the average δ18O values and the temperature signal during the austral summer season is detectable. δ18O, d-excess, and snow accumulation correlate with sea surface temperature and sea ice extent in the Ross Sea sector. A coupled influence of the SAM, ASL, and ENSO climate indices is expected, because the oceanic environment in this region is influenced by them. The pronounced intrusion of oceanic moisture coupled with atmospheric circulation patterns over the Ross Sea region makes the Styx-M ice core a promising record of the local oceanic conditions, with the snow accumulation rate being a direct proxy. Additionally, the analysis of trace elements from 1979 to 1999 revealed the presence of crustal dust sourced from the Transantarctic Mountains, as well as non-crustal sources, both intricately linked with atmospheric transport. These results demonstrate that the contributions of-and variations in-oceanic conditions associated with atmospheric circulation changes are detectable and dominant in the Styx-M ice core. This study serves as a basis for interpreting longer parts of the Styx-M ice core.
RESUMEN
Dust concentrations in Greenland ice show pronounced glacial/interglacial variations with almost two orders of magnitude increase during the Last Glacial Maximum. Greenland glacial dust was previously sourced to two East Asian deserts: the Taklimakan and Gobi deserts. Here we report the first high-resolution Pb and Sr isotopic evidence for a significant Saharan dust influence in Greenland during the last glacial period, back to ~31 kyr ago, from the Greenland NEEM ice core. We find that during Greenland Stadials 3-5.1 (~31 to 23 kyr ago), the primary dust provenance was East Asia, as previously proposed. Subsequently, the Saharan isotopic signals emerge during Greenland Stadials 2.1a-2.1c (~22.6 to 14.7 kyr ago) and from the late Bølling-Allerød to the Younger Dryas periods (~13.6 to 12 kyr ago), coincident with increased aridity in the Sahara and efficient northward transport of dust during these cold periods. A mixing isotopic model proposes the Sahara as an important source, accounting for contribution to Greenland glacial dust of up to 50%, particularly during Greenland Stadial 2.1b and the late Bølling-Allerød to the Younger Dryas periods. Our findings provide new insights into climate-related dust provenance changes and essential paleoclimatic constraints on dust-climate feedbacks in northern high latitudes.
RESUMEN
Lead (Pb), cadmium (Cd), copper (Cu) and zinc (Zn) have been measured by electrothermal atomic absorption spectrometry in various sections of the 3623 m deep ice core drilled at Vostok, in central East Antarctica. The sections were dated from 240 to 410 kyear BP (Marine Isotopic Stages (MIS) 7.5 to 11.3), which corresponds to the 3rd and 4th glacial-interglacial cycles before present. Concentrations are found to have varied greatly during this 170 kyear time period, with high concentration values during the coldest climatic stages such as MIS 8.4 and 10.2 and much lower concentration values during warmer periods, such as the interglacials MIS 7.5, 9.3 and 11.3. Rock and soil dust were the dominant sources for Pb, whatever the period, and for Zn and Cu and possibly Cd during cold climatic stages. The contribution from volcanic emissions was important for Cd during all periods and might have been significant for Cu and Zn during warm periods.
