Late Holocene diatoms in sediment cores from the Gonggeomji Wetland in Korea

2020 ◽  
Vol 35 (3) ◽  
pp. 195-229 ◽  
Author(s):  
Sang Deuk Lee ◽  
Hoil Lee ◽  
Jinsoon Park ◽  
Suk Min Yun ◽  
Jin-Young Lee ◽  
...  
Keyword(s):  
Late Holocene ◽  
Sediment Cores

scholarly journals Vulnerability of the North Water ecosystem to climate change

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sofia Ribeiro ◽  
Audrey Limoges ◽  
Guillaume Massé ◽  
Kasper L. Johansen ◽  
William Colgan ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Late Holocene ◽  
Sediment Cores ◽  
Arctic Ecosystems ◽  
Little Auk ◽  
The North ◽  
Water Ecosystem ◽  
North Water

AbstractHigh Arctic ecosystems and Indigenous livelihoods are tightly linked and exposed to climate change, yet assessing their sensitivity requires a long-term perspective. Here, we assess the vulnerability of the North Water polynya, a unique seaice ecosystem that sustains the world’s northernmost Inuit communities and several keystone Arctic species. We reconstruct mid-to-late Holocene changes in sea ice, marine primary production, and little auk colony dynamics through multi-proxy analysis of marine and lake sediment cores. Our results suggest a productive ecosystem by 4400–4200 cal yrs b2k coincident with the arrival of the first humans in Greenland. Climate forcing during the late Holocene, leading to periods of polynya instability and marine productivity decline, is strikingly coeval with the human abandonment of Greenland from c. 2200–1200 cal yrs b2k. Our long-term perspective highlights the future decline of the North Water ecosystem, due to climate warming and changing sea-ice conditions, as an important climate change risk.

scholarly journals Assessing ice margin fluctuations on differing timescales: Chronological constraints from Sermeq Kujatdleq and Nordenskiöld Gletscher, central West Greenland

The Holocene ◽  
2018 ◽  
Vol 28 (7) ◽  
pp. 1160-1172 ◽  
Author(s):  
Samuel E Kelley ◽  
Jason P Briner ◽  
Sandy L O’Hara
Keyword(s):  
Late Holocene ◽  
Sediment Cores ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Ice Dynamics ◽  
West Greenland ◽  
Southern Site ◽  
Ice Velocity ◽  
Observational Record ◽  
Local Variability

The observational record of ice margin position reveals asynchrony in both the timing and magnitude of Greenland Ice Sheet (GrIS) margin fluctuations and illustrates the complex reactions of ice sheets to climatic perturbations. In this study, we reconstruct the timing and pattern of middle- and late-Holocene GrIS margin fluctuations at two locations, ~190 km apart, in central West Greenland using radiocarbon-dated sediment cores from proglacial-threshold lakes. Our results demonstrate that deglaciation occurs at both sites during the early Holocene, with the ice sheet remaining in a smaller-than-present ice margin configuration until ~500 years ago when it readvanced into lake catchments at both sites. At our northern site, Sermeq Kujatdleq, the late-Holocene advance of the GrIS approached maximum position during the past 280 years, with the culmination of the advance occurring at AD 1992–1994, and modern retreat was underway by AD 1998–2001. In contrast, field and observational evidence suggest that the GrIS at our southern site, Nordenskiöld Gletscher, has been advancing or stable throughout the 20th century. These results, in conjunction with previous work in the region, highlight the asynchronous nature of late-Holocene advances and subsequent modern retreat, implying that local variability, such as ice velocity or ice dynamics, is responsible for modulating ice margin response to changes in climate on these decadal to centennial timescales. Additional high-resolution records of past ice sheet fluctuations are needed to inform and more accurately constrain our predictions of future cryosphere response to changes in climate.

A comparative study of radiocarbon dating on terrestrial organisms and fish from Qinghai Lake in the northeastern Tibetan Plateau, China

The Holocene ◽  
2018 ◽  
Vol 28 (11) ◽  
pp. 1712-1719 ◽  
Author(s):  
E ChongYi ◽  
YongJuan Sun ◽  
XiangJun Liu ◽  
Guangliang Hou ◽  
ShunChang Lv ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Late Holocene ◽  
Sediment Cores ◽  
Qinghai Lake ◽  
The Tibetan Plateau ◽  
Fish Bones ◽  
Northeastern Tibetan Plateau ◽  
Animal Bones ◽  
Gymnocypris Przewalskii ◽  
The Difference

Qinghai Lake is the largest lake on the Tibetan Plateau (TP) and in China and has been a focus of paleoenvironmental and climatic research for decades. However, limited understanding of lake 14C reservoir effects (LRE) has led to inconsistent interpretations among proxies of different sediment cores. As such, the onset of LRE variability during the Holocene is still unclear. 14C dating of archeological samples from four locations (Gangcha, Shaliuheqiaoxi, and Shinaihai sites, and Niaodao section) including naked carp ( Gymnocypris przewalskii, Kessler) fish bones, animal bones and teeth, and charcoal was employed to estimate variations in LRE over the last few thousand years. LRE offsets calculated as the difference between LRE of animal bones and fish bones are more reliable than that of charcoal and fish bones due to the ‘old wood’ effect in charcoal. LRE offsets recorded in fish bones were ~0.5, ~0.6, and ~0.7 ka during the periods of 3.0–3.4 cal ka BP, 0.58–0.60 cal ka BP, and modern lake times, respectively, which may indicate a temporal minimum LRE offset. Unlike the wide spatial variations of LRE ages obtained from surface total organic carbon (TOC) samples of the modern Qinghai Lake, LRE offsets from the three contemporaneous locations in Qinghai Lake were all ~0.5 ka, suggesting efficient carbon mixing occurred in naked carp. However, the late-Holocene (~3.1 ka BP) LRE increased slightly with increasing salinity and decreasing lake level.

Forest stability during the early and late Holocene in the igapó floodplains of the Rio Negro, northwestern Brazil

2017 ◽  
Vol 89 (1) ◽  
pp. 75-89 ◽  
Author(s):  
Paula A. Rodríguez-Zorro ◽  
Bruno Turcq ◽  
Renato C. Cordeiro ◽  
Luciane S. Moreira ◽  
Renata L. Costa ◽  
...  
Keyword(s):  
Late Holocene ◽  
Amazon Basin ◽  
Vegetation History ◽  
Sediment Cores ◽  
Northwestern Part ◽  
Human Disturbances ◽  
River Dynamics ◽  
Rio Negro ◽  
Igapó Forest ◽  
Forest Stability

AbstractLocated at the northwestern part of the Amazon basin, Rio Negro is the largest black-water river in the world and is one of the poorest studied regions of the Amazon lowlands. In the middle-upper part of the Rio Negro were retrieved sediment cores form Lake Acarabixi, which were analyzed using pollen, spores, charcoal, and geochemistry. The aim of this study was to detect the influences from humans and river dynamics on the vegetation history in the region. Two main periods of vegetation and river dynamics were detected. From 10,840 to 8240 cal yr BP, the river had a direct influence into the lake. The lake had a regional input of charcoal particles, which reflected the effect of the dry Holocene period in the basin. Furthermore, highland taxa such asHedyosmumandMyrsinewere found at that time along with igapó forest species that are characteristic to tolerate extended flooding likeEschweilera,Macrolobium, Myrtaceae,Swartzia, andAstrocaryum. During the late Holocene (1600 to 650 cal yr BP), more lacustrine phases were observed. There were no drastic changes in vegetation but the presence of pioneer species likeVismiaandCecropia, along with the signal of fires, which pointed to human disturbances.

Late Holocene glacier and climate reconstruction from proglacial records in Vatnsdalur, northern Iceland.

2020 ◽  
Author(s):  
Konstantin Nebel ◽  
Timothy Lane ◽  
Kathryn Adamson ◽  
Iestyn Barr ◽  
Willem van der Bilt ◽  
...  
Keyword(s):  
High Resolution ◽  
Environmental Change ◽  
North Atlantic ◽  
Late Holocene ◽  
Sediment Cores ◽  
Arctic Region ◽  
Arctic Climate ◽  
The Arctic ◽  
Air Masses ◽  
Proglacial Lake

<p>The Arctic region is experiencing surface air temperature increase of twice the global average. To better understand Holocene Arctic climate variability, there is the need for continuous, high-resolution palaeoclimate archives. Sediment cores from proglacial lakes can provide such climate archives, and have the potential to record past environmental change in detail.       </p><p>Vatnsdalur, a valley in northern Iceland, hosts small, climatically sensitive cirque glaciers that became independent from the Iceland Ice Sheet after its retreat following the Last Glacial Maximum (c. 15 ka BP). Importantly, this region is located at the confluence of warm water and air masses from the south and cold polar water and air masses from the north, making it highly sensitive to North Atlantic and Arctic climate change. However, at present the region is highly understudied, lacking any high-resolution climate reconstructions.           </p><p>To address this, we combine geomorphological mapping with the first high-resolution analysis of proglacial lake sediments, to thoroughly examine northern Iceland Late Holocene environmental change.</p><p>Field mapping supplemented by high-resolution drone data was used to characterise catchment geomorphology, including seven Holocene moraines. A sediment core (SKD-P1-18) from proglacial lake Skeiðsvatn, Vatnsdalur, was analysed for sedimentological (dry bulk density, loss-on-ignition, grain size), geophysical (magnetic susceptibility) and geochemical (X-ray fluorescence core scan, 2 mm resolution) parameters.             <br>We identify three main sedimentary facies from these analyses, indicating variations in glacial input and catchment environmental conditions. Radiocarbon dating of lake macrofossils, supplemented by tephrochronology, provides a chronological framework. Catchment point samples, also analysed using the above analytical techniques, were used for sediment fingerprinting to disentangle non-glacial from glacial end-members.</p><p>Our results indicate the disappearance and reformation of small, climatically sensitive cirque glaciers in Vatnsdalur during the Holocene. We interpret the data to show an abrupt return to a glaciated catchment. Our results fill a geographical gap of high-resolution proglacial sediment studies in the Arctic-North Atlantic region.</p>

Late-Holocene evolution of a coastal lagoon in the Gulf of Lions (South of France)

2010 ◽  
Vol 181 (1) ◽  
pp. 27-36 ◽  
Author(s):  
Pierre Sabatier ◽  
Laurent Dezileau ◽  
Mickaël Barbier ◽  
Olivier Raynal ◽  
Johanna Lofi ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Coastal Lagoon ◽  
Late Holocene ◽  
Accumulation Rate ◽  
Sediment Cores ◽  
Coastal System ◽  
Gulf Of Lions ◽  
Marine Sand ◽  
Radiocarbon Data

Abstract The central part of the Gulf of Lions shoreline is characterized by many coastal wetlands that resulted from the interaction between a process of shoreline regularization by migrations of littoral barriers and a slow filling of the back-barrier areas by the riverine and marine inputs. Analyses of Late-Holocene deposits with a very high-resolution multi-proxy study of two sediment cores, allow us to reconstruct the evolution of this coastal system. Two main Holocene sediment units are identified overlying a Pliocene carbonate continental formation. The lower unit consists of sandy and pebbly marine sediments deposited around 7800 B.P., during the final stand of the last sea level rise. Just above, the upper unit displays lagoonal grey clay silts with shells and some intercalated layers of silty sands related to paleostorm events. The age model was established from radiocarbon dating, for the oldest part of the core. Over the last century, sedimentation rates were calculated using the CFCS 210Pb model, together with 137Cs data. Radiocarbon data show an increase in the accumulation rate from the base to the top of cores. Marine sand units related to the last transgressive deposit allow to refine the curve of Holocene post-glacial sea level rise. Sedimentological and faunal analyses associated with chronological data provide a means for reconstructing the Late-Holocene paleoenvironments along this part of the coast and suggest that the final closure of the coastal lagoon by the sandy barrier occurred at around 730 ± 120 yr cal B.P. The beginning of this closure, together with the progradation of the coastal plain, could be responsible for the decline in economic activity of the Lattara harbour during the Roman period.

Late Holocene precipitation variability recorded in the sediments of Reloncaví Fjord (41°S, 72°W), Chile

2015 ◽  
Vol 84 (1) ◽  
pp. 21-36 ◽  
Author(s):  
Lorena Rebolledo ◽  
Carina B. Lange ◽  
Sébastien Bertrand ◽  
Práxedes Muñoz ◽  
Marco Salamanca ◽  
...  
Keyword(s):  
Late Holocene ◽  
Sediment Cores ◽  
Southern Annular Mode ◽  
Organic Carbon Content ◽  
Diatom Assemblages ◽  
Chilean Patagonia ◽  
Precipitation Seasonality ◽  
Rhizosolenia Setigera ◽  
First Occurrence ◽  
Instrumental Records

We present reconstructions of late Holocene changes in the source of organic matter and siliceous export production in the Relocanví Fjord (41°S, 72°W), Northern Chilean Patagonia, based on organic carbon content, δ13Corg, N/C ratio, diatom assemblages and biogenic silica contents from three sediment cores. The age models are based on a combination of 210Pb profiles, AMS 14C dating, and on the first occurrence of the diatom Rhizosolenia setigera f. pungens, as a stratigraphic marker in the fjords. The cores span the last 300 to 700 yr. Diatoms dominate the siliceous assemblages in the three cores (98% on average). Our results suggest that precipitation seasonality in the region of Reloncaví was high in CE 1300–1400 and CE 1700–1850, with a clear decreasing trend since CE 1850. The latter trend is in agreement with instrumental records and tree-ring reconstructions. These fluctuations seem to be associated with the Southern Annular Mode (SAM).

scholarly journals The Holocene dynamics of Ryder Glacier and ice tongue in north Greenland

2021 ◽  
Vol 15 (8) ◽  
pp. 4073-4097
Author(s):  
Matt O'Regan ◽  
Thomas M. Cronin ◽  
Brendan Reilly ◽  
Aage Kristian Olsen Alstrup ◽  
Laura Gemery ◽  
...  
Keyword(s):  
Climate Change ◽  
Late Holocene ◽  
Sediment Cores ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Sedimentary Facies ◽  
Climate Forcing ◽  
The Holocene ◽  
Middle Holocene ◽  
Vulnerability To Climate Change

Abstract. The northern sector of the Greenland Ice Sheet is considered to be particularly susceptible to ice mass loss arising from increased glacier discharge in the coming decades. However, the past extent and dynamics of outlet glaciers in this region, and hence their vulnerability to climate change, are poorly documented. In the summer of 2019, the Swedish icebreaker Oden entered the previously unchartered waters of Sherard Osborn Fjord, where Ryder Glacier drains approximately 2 % of Greenland's ice sheet into the Lincoln Sea. Here we reconstruct the Holocene dynamics of Ryder Glacier and its ice tongue by combining radiocarbon dating with sedimentary facies analyses along a 45 km transect of marine sediment cores collected between the modern ice tongue margin and the mouth of the fjord. The results illustrate that Ryder Glacier retreated from a grounded position at the fjord mouth during the Early Holocene (> 10.7±0.4 ka cal BP) and receded more than 120 km to the end of Sherard Osborn Fjord by the Middle Holocene (6.3±0.3 ka cal BP), likely becoming completely land-based. A re-advance of Ryder Glacier occurred in the Late Holocene, becoming marine-based around 3.9±0.4 ka cal BP. An ice tongue, similar in extent to its current position was established in the Late Holocene (between 3.6±0.4 and 2.9±0.4 ka cal BP) and extended to its maximum historical position near the fjord mouth around 0.9±0.3 ka cal BP. Laminated, clast-poor sediments were deposited during the entire retreat and regrowth phases, suggesting the persistence of an ice tongue that only collapsed when the glacier retreated behind a prominent topographic high at the landward end of the fjord. Sherard Osborn Fjord narrows inland, is constrained by steep-sided cliffs, contains a number of bathymetric pinning points that also shield the modern ice tongue and grounding zone from warm Atlantic waters, and has a shallowing inland sub-ice topography. These features are conducive to glacier stability and can explain the persistence of Ryder's ice tongue while the glacier remained marine-based. However, the physiography of the fjord did not halt the dramatic retreat of Ryder Glacier under the relatively mild changes in climate forcing during the Holocene. Presently, Ryder Glacier is grounded more than 40 km seaward of its inferred position during the Middle Holocene, highlighting the potential for substantial retreat in response to ongoing climate change.

Analysis of hemlock pollen size in Holocene lake sediments from New England

2013 ◽  
Vol 79 (3) ◽  
pp. 362-365 ◽  
Author(s):  
Lindsay T. Day ◽  
W. Wyatt Oswald ◽  
Elaine D. Doughty ◽  
David R. Foster
Keyword(s):  
New England ◽  
Late Holocene ◽  
Surface Sediments ◽  
Sediment Cores ◽  
Pollen Grains ◽  
Tsuga Canadensis ◽  
Pollen Size ◽  
Middle Holocene ◽  
European Settlement ◽  
Fossil Records

AbstractWe explored the middle-Holocene decline of Tsuga canadensis by measuring the diameters of pollen grains in two lake-sediment cores from New England. We hypothesized that a drop in pollen size at the time of the decline followed by an increase in pollen diameters as Tsuga recovered during the late Holocene might indicate reduced abundance of Tsuga in the vicinity of the lake during the decline, as smaller pollen grains travel farther than larger ones. To provide context for this hypothesis, we also measured the diameters of Tsuga pollen grains in the surface sediments of sites spanning the modern-day gradient of Tsuga in New England. Both fossil records exhibited a reduction in pollen size during the interval of the middle-Holocene decline, with diameters similar to those observed in the upper sediments of those sites, yet larger than Tsuga pollen grains in the surface sediments of coastal sites beyond the modern range of Tsuga. This pattern suggests that Tsuga persisted in scattered, low-density populations during the middle Holocene, as it has remained on the landscape since European settlement.

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