Abstract:Benthic ecosystems of perennially ice-covered lakes in Antarctica are highly sensitive to climate-driven changes. Lake Untersee has been in hydrological steady-state for several hundred years with a high pH water column and extremely low levels of dissolved inorganic carbon. Here, we show that glacial lake outburst floods can replenish carbon dioxide-depleted lakes with carbon, enhancing phototrophic activity of the benthic ecosystem. In 2019, a glacial lake outburst flood brought 17.5 million m3 of water to L… Show more
“…Evidence of these different outburst mechanisms have been observed in the field at Antarctic glacial lakes, even though Antarctic GLOF studies are limited. For example, the 2019 Untersee GLOF was initiated by water outflow at the lake margin, which was confirmed by field inspections 25 . The Yatsude Valley GLOF was probably caused via the subglacial hydrological system, with the formation of a near-circular hole at/near the base of the ice dam inferred 23 .…”
Section: Discussionmentioning
confidence: 61%
“…2 ). The total discharge volumes from LKI during P1 and P2 are four times larger than the 2019 GLOF event at Lake Untersee, a glacier-dammed lake in East Antarctica 25 , thereby making these LKI events two of the largest GLOFs reported at an ice-marginal lake in Antarctica to date. Figure 2 LKI elevation profiles.…”
Section: Resultsmentioning
confidence: 88%
“…For example, GLOFs from the largest-scale glacial lakes that were located along the periphery of past ice sheets weakened ocean circulation, thereby modulating climate 21,22 . However, GLOFs from ice-marginal and ice-dammed lakes in Antarctica have largely been neglected due to extremely limited reports of GLOFs until recently [23][24][25][26] . Although outbursts from subglacial, supraglacial, and sub-surface lakes are generally associated with either a collapse of the surrounding ice or ice doline formation [27][28][29] , the subglacial and englacial hydrological processes behind such events are not well constrained due to the rarity of these events and the inherent difficulty…”
The liquid water around the Antarctic Ice Sheet plays a key role in modulating both the vulnerability of ice shelves to hydrofracturing and ice discharge from outlet glaciers. Therefore, it needs to be adequately constrained for precise future projections of ice-mass loss and global sea-level rise. Although glacial lake outburst floods (GLOFs) pose one of the greatest risks in glacierized mountainous regions, any long-term monitoring of Antarctic ice-marginal lakes and their associated potential for GLOFs has been neglected until recently owing to the limited number of such events reported in Antarctica. Here we present direct evidence of repeated GLOFs from Lake Kaminotani-Ike, an ice-sheet-dammed lake in East Antarctica, via an analysis of historical aerial photographs and recent satellite data. Two GLOFs occurred in 1969–1971 and 2017, with discharge volumes of (8.6 ± 1.5) × 107 and (7.1 ± 0.4) × 107 m3, respectively, making them two of the largest GLOFs in Antarctica. A southerly oceanward pathway beneath the ice sheet is the most likely drainage route of these GLOF events based on the available surface- and bed-elevation datasets. Furthermore, the 2017 event occurred during the austral winter, thereby implying the possibility of year-round active subglacial networks in Antarctica. Our results highlight that studies on Antarctic ice-marginal lakes provide an opportunity to better understand Antarctic hydrological processes and emphasize the need for both detailed monitoring of ice-marginal lakes and detailed surveying of the subglacial environments of the Antarctic Ice Sheet.
“…Evidence of these different outburst mechanisms have been observed in the field at Antarctic glacial lakes, even though Antarctic GLOF studies are limited. For example, the 2019 Untersee GLOF was initiated by water outflow at the lake margin, which was confirmed by field inspections 25 . The Yatsude Valley GLOF was probably caused via the subglacial hydrological system, with the formation of a near-circular hole at/near the base of the ice dam inferred 23 .…”
Section: Discussionmentioning
confidence: 61%
“…2 ). The total discharge volumes from LKI during P1 and P2 are four times larger than the 2019 GLOF event at Lake Untersee, a glacier-dammed lake in East Antarctica 25 , thereby making these LKI events two of the largest GLOFs reported at an ice-marginal lake in Antarctica to date. Figure 2 LKI elevation profiles.…”
Section: Resultsmentioning
confidence: 88%
“…For example, GLOFs from the largest-scale glacial lakes that were located along the periphery of past ice sheets weakened ocean circulation, thereby modulating climate 21,22 . However, GLOFs from ice-marginal and ice-dammed lakes in Antarctica have largely been neglected due to extremely limited reports of GLOFs until recently [23][24][25][26] . Although outbursts from subglacial, supraglacial, and sub-surface lakes are generally associated with either a collapse of the surrounding ice or ice doline formation [27][28][29] , the subglacial and englacial hydrological processes behind such events are not well constrained due to the rarity of these events and the inherent difficulty…”
The liquid water around the Antarctic Ice Sheet plays a key role in modulating both the vulnerability of ice shelves to hydrofracturing and ice discharge from outlet glaciers. Therefore, it needs to be adequately constrained for precise future projections of ice-mass loss and global sea-level rise. Although glacial lake outburst floods (GLOFs) pose one of the greatest risks in glacierized mountainous regions, any long-term monitoring of Antarctic ice-marginal lakes and their associated potential for GLOFs has been neglected until recently owing to the limited number of such events reported in Antarctica. Here we present direct evidence of repeated GLOFs from Lake Kaminotani-Ike, an ice-sheet-dammed lake in East Antarctica, via an analysis of historical aerial photographs and recent satellite data. Two GLOFs occurred in 1969–1971 and 2017, with discharge volumes of (8.6 ± 1.5) × 107 and (7.1 ± 0.4) × 107 m3, respectively, making them two of the largest GLOFs in Antarctica. A southerly oceanward pathway beneath the ice sheet is the most likely drainage route of these GLOF events based on the available surface- and bed-elevation datasets. Furthermore, the 2017 event occurred during the austral winter, thereby implying the possibility of year-round active subglacial networks in Antarctica. Our results highlight that studies on Antarctic ice-marginal lakes provide an opportunity to better understand Antarctic hydrological processes and emphasize the need for both detailed monitoring of ice-marginal lakes and detailed surveying of the subglacial environments of the Antarctic Ice Sheet.
“…Benthic, photosynthetic microbial mats are present to depths exceeding 130 m. Small pinnacle mats up to 15 cm tall form at depths between 10 m and 15 m. Conical structures up to 70 cm tall form at depths between 10 m and 130 m ( 1 , 2 ). Samples were obtained from pinnacle mats collected at 13 m using 50-mL Falcon tubes in fall 2019.…”
Here, we report the draft genome sequence for a new putative genus and species in the family
M1A02
within the order
Phycisphaerales
. Isolated from the metagenome of a benthic pinnacle-shaped mat in the Antarctic Lake Untersee, the members of this family have been found in biofilms and freshwater environments.
“…Currently, water and sediment are mostly studied media for DOM in lakes, with subglacial lakes in Antarctica being the focus of most studies. The total organic carbon (TOC) content of Antarctic lakes is between 0.3-0.4 mg/L, only 4.68%-5.71% of that in lakes in warm regions, because the poor lighting conditions limit the growth of phytoplankton (Chen et al 2016;Faucher et al 2021) By contrast, the nutrient content of lakes in the cold-arid regions of the Yellow River Basin plateau is significantly higher than that of lakes in Antarctica, because of climate change and human activities (Yang et al 2021). Therefore, although the lakes in the Yellow River Basin share some common characteristics (i.e., lack of light, low DO content, and low microbial activity) with the lakes in Antarctica, they are at higher risk of potential eutrophication.…”
During freezing periods, nutrients (carbon and organic matter, etc.) are enriched in the water and sediment of lakes in cold-arid regions, leading to potential algal bloom outbreaks and other health risks to the ecosystem. Particularly, dissolved organic matter (DOM) is a critical component of the nutrients and plays an important role in the global carbon cycle. However, the mechanisms of DOM transfer between ice and water remain unclear. This study analyzed the influence of microbial community on DOM composition using 16 s RNA, 3DEEM, and FT-ICR MS in Daihai Lake and Wuliangsuhai Lake in the Yellow River Basin, China. According to the spectral analysis, the content of endogenous organic matter, such as humus, accounted for 40% of the total DOM in water, while the content of tryptophan and tyrosine accounted for 80% of the total DOM in ice. The results of mass spectrometry showed that lignin was the main component, and the content of organic matter in the ice was less than that in the water. Molecular structures of seven DOM coexisting in the lake ice and water were elucidated with adapted Kendrick-analogous network visualization, which clearly illustrates that long-chain DOM molecules are derived from small molecules, while other heteroatoms are complexed with the side groups. The positive correlations between CHO, CHNO, CHOS, CHOS and Actinomyces indicate that DOM actively interacted with the microbial community. 44% of CHO compounds have the same molecular formula in water, the content of CHOS in the water of the two lakes was closed to 7% higher than that in the ice. Meanwhile, DOM dynamically migrate between ice and water via interstitial water because of the solubility changes under microbial transformation, which has been proved by the decrease in the contents of the humus and tryptophan-like substances in the ice from the bottom to the surface and lower contents of carbohydrate and unsaturated aromatic hydrocarbon in the water than the ice. This study helps to predict the composition and structure of DOM during the migration in lakes and provides a scientific basis for environmental remediation with high concentration of carbon.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
