Soluble salts in deserts as a source of sulfate aerosols in an Antarctic ice core during the last glacial period

Sulfur Isotope Geochemistry of Ice‐Wedges in Yakutia, East Siberia

“…Since thick ice sheets cover almost the entire continent, the contribution of nearby crustal rocks or vegetation to ice‐core sulfate should be limited. Instead, long‐range transport of marine biogenic emissions or terrestrial dust from lower latitudes may be the major source of sulfate deposition in the interior of the ice sheet [18, 113–115]. Although not sulfate, a comparison of strontium and neodymium isotope data from the interior and periphery of the Greenland Ice Sheet showed a negligible relative contribution from long‐range transport only in the vicinity of exposed basement rocks [116].…”

“…Terrestrial sulfate can be derived directly from the weathering of evaporitic sulfate minerals, and also, sulfide minerals such as pyrite can be oxidized to form sulfate minerals or aqueous sulfate, especially when they are exposed to the oxidizing conditions of the Earth's surface [73]. Because glacial abrasion is an effective means of eroding bedrock and transforming it into fine-grained rock flour [74], glaciers flowing from the highlands into the lowlands could enhance the weathering of sulfur-bearing minerals and contribute to the regional production of sulfate aerosols [18,75]. During the Pleistocene and afterwards, the East Siberian Arctic lowlands, including our study sites, were not glaciated but rimmed by mountain glaciers (Figure 1A; [27,36,76,77]).…”

“…To the best of our knowledge, this is the first study to assess the sulfur isotopic composition of sulfate, POM, and lithic particles in ice-wedges, and using sulfur isotope geochemistry of ice-wedges as a paleoclimatic or paleoenvironmental archive is in its infancy. For the ice sheets, however, there have been a few reports on temporal δ 34 S SO4 variations from ice-cores in Antarctica and Greenland [18,25,[109][110][111][112]. Although many of them cover relatively short time intervals of a few thousand years, focusing on the mass-independently fractionated sulfate associated with large volcanic eruptions, a long-term δ 34 S SO4 record, spanning the last glacial-Holocene transition, has been recently obtained from the Dome Fuji ice-core [18].…”

“…For the ice sheets, however, there have been a few reports on temporal δ 34 S SO4 variations from ice-cores in Antarctica and Greenland [18,25,[109][110][111][112]. Although many of them cover relatively short time intervals of a few thousand years, focusing on the mass-independently fractionated sulfate associated with large volcanic eruptions, a long-term δ 34 S SO4 record, spanning the last glacial-Holocene transition, has been recently obtained from the Dome Fuji ice-core [18]. There, icecore δ 34 S SO4 was maintained at the present-day level throughout the Holocene, but during the last glaciation, the sulfur isotopic composition was depleted in 34 S by about 4‰ compared with the Holocene.…”

“…Because sulfate, among the most abundant anions in atmospheric aerosols, tends to be conservative under aerobic conditions, sulfur isotope ratios of sulfate trapped in ice archives have provided insight into the origin of sulfate aerosols. Thus, long‐term fluctuations in the sulfur isotope ratio of sulfate indicate shifts in the relative contributions of isotopically distinct sulfate sources, potentially triggered by climate change [18]. In inland ice‐wedges, however, the source of atmospheric sulfate has never been isotopically constrained.…”