scholarly journals The Progress of Quantitative Reconstruction of Lake Processes and Catchment Environmental Changes Based on Lake Sediment in China

2010 ◽  
Vol 15 (2) ◽  
pp. 44-55
Author(s):  
Ji SHEN ◽  
Enlou ZHANG ◽  
Yanhong WU ◽  
Yong WANG ◽  
Xiangdong YANG
Keyword(s):  
Lake Sediment ◽  
Environmental Changes ◽  
Quantitative Reconstruction

The Holocene environmental changes in southern Indonesia reconstructed from highland caldera lake sediment in Bali Island

2015 ◽  
Vol 374 ◽  
pp. 15-33 ◽  
Author(s):  
Yu Fukumoto ◽  
Xun Li ◽  
Yoshinori Yasuda ◽  
Makoto Okamura ◽  
Kazuyoshi Yamada ◽  
...  
Keyword(s):  
Lake Sediment ◽  
Environmental Changes ◽  
The Holocene

scholarly journals Lateglacial and Holocene environmental change in the area of Samogitian Upland (NW Lithuania): records from Lopaičiai and Pakastuva sites

Baltica ◽  
2015 ◽  
Vol 28 (2) ◽  
pp. 163-178 ◽  
Author(s):  
Meilutė Kabailienė ◽  
Giedrė Vaikutienė ◽  
Lina Macijauskaitė ◽  
Eugenija Rudnickaitė ◽  
Rimantė Guobytė ◽  
...  
Keyword(s):  
Environmental Change ◽  
Lake Sediment ◽  
Vegetation Cover ◽  
Environmental Changes ◽  
Sediment Cores ◽  
14C Dating ◽  
Plant Macrofossil ◽  
Study Results ◽  
Environmental Development ◽  
Holocene Environmental Change

Pollen, plant macrofossil and carbonate analyses supplemented with 14C dating were applied for Lopaičiai hollow and Pakastuva Lake sediment sequences. The new data obtained from two sediment cores were used to reconstruct vegetation cover and environmental changes during Lateglacial and Holocene in Samogitian Upland (NW Lithuania). Different burial conditions of dead ice blocks caused different time of lake sediment start in studied sites. The depositional and vegetation cover history is traced starting at pre-Allerød time in sediment sequence from Lopaičiai core. However, sediment sequence from Pakastuva core provides paleoenvironmental information starting only from the very beginning of Holocene. The study results bring more light on environmental development during Lateglacial and Holocene of specific ice marginal area, which is interlobate insular upland.

Numbers, activities, and diversity of autotrophic ammonia-oxidizing bacteria in a freshwater, eutrophic lake sediment

1991 ◽  
Vol 37 (11) ◽  
pp. 828-833 ◽  
Author(s):  
W. T. Smorczewski ◽  
E. L. Schmidt
Keyword(s):  
Lake Sediment ◽  
Environmental Changes ◽  
Ammonia Oxidation ◽  
Eutrophic Lake ◽  
Ammonia Oxidizer ◽  
Most Probable Number ◽  
Ammonia Oxidizing Bacteria ◽  
Ammonia Oxidizers ◽  
Probable Number ◽  
Nitrite Oxidizers

The microbiological and chemical potential for ammonia oxidation in a freshwater, eutrophic lake sediment was examined in relation to environmental changes caused by seasonal, dimictic circulation. Poulations of both ammonia and nitrite oxidizers as estimated by most probable number (MPN) were sustained throughout extended anaerobic summer intervals, with nitrite oxidizers outnumbering ammonia oxidizers by a factor ranging from 3.0 to 8.1. Ammonia oxidation potential on a per cell basis was affected by seasonal changes and was seen to decrease as oxygen was removed from the sediments. Pure-culture isolations from a positive MPN tube inoculated with oxygenated sediment and representing a single point in a seasonal cycle produced ammonia-oxidizing strains belonging to the genus Nitrosospira. These strains did not react with known ammonia-oxidizer serotypes and, therefore, extend the serological diversity of this group of bacteria. An immunofluorescence analysis of MPN tubes from sediment collected during a period of lake stratification revealed progressive changes in the diversity of the ammonia-oxidizer population. The genera Nitrosomonas, Nitrosolobus, and Nitrosospira, including the novel serotype of Nitrosospira isolated from the sediment a year earlier, were found to coexist in well-oxygenated sediment. This diversity was seen to disappear, with Nistrosomonas surviving, as anaerobic conditions persisted. Key words: ammonia oxidizers, lake sediments, nitrifiers, nitrification.

Reconstruction of Prehistoric Landfall Frequencies of Catastrophic Hurricanes in Northwestern Florida from Lake Sediment Records

2000 ◽  
Vol 54 (2) ◽  
pp. 238-245 ◽  
Author(s):  
Kam-biu Liu ◽  
Miriam L. Fearn
Keyword(s):  
Lake Sediment ◽  
Environmental Changes ◽  
Gulf Coast ◽  
Sediment Cores ◽  
Jet Stream ◽  
Lake Area ◽  
Western Lake ◽  
Sediment Records ◽  
First Millennium ◽  
Florida Panhandle

Sediment cores from Western Lake provide a 7000-yr record of coastal environmental changes and catastrophic hurricane landfalls along the Gulf Coast of the Florida Panhandle. Using Hurricane Opal as a modern analog, we infer that overwash sand layers occurring near the center of the lake were caused by catastrophic hurricanes of category 4 or 5 intensity. Few catastrophic hurricanes struck the Western Lake area during two quiescent periods 3400–5000 and 0–1000 14C yr B.P. The landfall probabilities increased dramatically to ca. 0.5% per yr during an “hyperactive” period from 1000–3400 14C yr B.P., especially in the first millennium A.D. The millennial-scale variability in catastrophic hurricane landfalls along the Gulf Coast is probably controlled by shifts in the position of the jet stream and the Bermuda High.

Extending the applicability of the REVEALS model for pollen-based vegetation reconstructions to coastal lagoons

The Holocene ◽  
2019 ◽  
Vol 29 (7) ◽  
pp. 1109-1112
Author(s):  
Julien Azuara ◽  
Florence Mazier ◽  
Vincent Lebreton ◽  
Shinya Sugita ◽  
Nicolas Viovy ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Coastal Lagoons ◽  
Pollen Dispersal ◽  
Local Scale ◽  
Mechanistic Models ◽  
Pollen Data ◽  
Plant Abundance ◽  
Quantitative Reconstruction ◽  
Quantitative Estimates ◽  
Lake Deposits

Quantitative reconstruction of past plant abundance from fossil pollen data is still a challenging task for palynologists. During the last decades, mechanistic methods have been developed to convert pollen assemblages from peat and lake deposits into vegetation abundance at regional and local scale. Coastal areas are particularly sensitive to climate and environmental hazards. Thus, quantitative estimates of past vegetation are important to better understand their history and address potential effects of future environmental changes. However, assumptions of the mechanistic models of pollen dispersal and deposition originally designed for near-circular lakes and bogs located inland are violated when applied to coastal sites because of different basin shape and wind direction distribution. This study investigates how to adapt a model of pollen dispersal and deposition developed for lakes to coastal lagoons. A new geometry is defined, and it is demonstrated how some of the major formulas from previous models can be used without any modification in this singular context.

Geomorphology of the lakebed and sediment deposition during the Holocene in Lake Visovac

2021 ◽  
Author(s):  
Nikolina Ilijanić ◽  
Slobodan Miko ◽  
Ozren Hasan ◽  
Dea Brunović ◽  
Martina Šparica Miko ◽  
...  
Keyword(s):  
High Resolution ◽  
Lake Sediment ◽  
National Park ◽  
Lake Level ◽  
Evolutionary Dynamics ◽  
Environmental Changes ◽  
Sediment Cores ◽  
Depositional Environments ◽  
Lake Levels ◽  
The Holocene

<p>Lake Visovac is a tufa barrier lake on the Krka River between Roški slap (60 m asl) and Skradinski buk (46 m absl) waterfalls, included in the Krka national park as primarily unaltered area of exceptional natural value. Paleolimnological research was conceived to address a lake evolution and depositional environments through the geophysical survey and collection of the lake sediment cores. A high-resolution bathymetric map was obtained using a multibeam sonar. The average lake depth varies between 20 and 25 m. Sediment cores were investigated to extract physical properties, sedimentological, mineralogical, geochemical and paleoecological records constrained by the radiocarbon chronology, to understand what was happening to both the landscapes and lakescapes of Lake Visovac during the last 2.000 cal yr.</p><p>Significant findings of the project are geomorphological features on the lake bottom: submerged sinkholes of various sizes (up to 40 m deep); submerged tufa barriers in the area of Kalički kuk (southern part of Lake Visovac) at the depths of 15 and 17 m, followed by a series of buried cascade tufa barriers at the depth of 25 m covered with up to 10 m of Holocene lake sediments; submerged vertical tufa barrier up to 32 m-high near the mouth of Čikola River; submerged landslides, small (river) fan structures characterized by sediment waves. Ground-penetrating-radar (GPR) data have been acquired due to the presence of gas-saturated sediments over a large area of the lake, that limited the use of high-resolution acoustic profiling. A total thickness of sediments is up to 40 m. High resolution paleoenvironmental record through the Late Holocene gives evidence of high sedimentation rates in Lake Visovac, variable soil erosion impact on lake sediment composition and carbonate authigenic sedimentation. Higher organic carbon is observed in the last 50 years due to changes in land cover and reforestation. Pleistocene lake sediment outcrops occur up to 20 m above the present lake levels indicating higher lake levels as a consequence of higher elevation of tuffa barriers. Kalički kuk, which lies up to 20 m above present lake level, is a remnant of these barriers which have been dated to MIS5. Results allow us to interpret the environmental and evolutionary dynamics of Lake Visovac in the following way: lake level more than 20 m higher than today in mid-Pleistocene with significantly larger lake volume in Lake Visovac, with active Kalički kuk and Skradinski buk waterfalls; lower lake-level at the beginning of the Holocene when several small lakes existed in isolated basins in the area of Lake Visovac. The tufa barrier at Skradinski buk started to grow faster than the Kalički kuk barriers and waterfalls resulting in their flooding and submergence during the Holocene. The tufa barrier at Skradinski buk has grown 15 m since then. This study demonstrates the role of geomorphological lakebed characteristics in reshaping our understanding of the environmental changes and the future of Lake Visovac.</p><p>The research was conducted as part of the project funded by the Krka National Park and CSF funded QMAD project (IP-04-2019-8505).</p>

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