Holocene coastal morphologies and shoreline reconstruction for the southwestern coast of the Bohai Sea, China

2016 ◽  
Vol 86 (2) ◽  
pp. 144-161 ◽  
Author(s):  
Yanxia Liu ◽  
Haijun Huang ◽  
Yali Qi ◽  
Xiao Liu ◽  
Xiguang Yang
Keyword(s):  
Sea Level ◽  
Marine Sediments ◽  
Bohai Sea ◽  
Yellow River ◽  
Water Levels ◽  
The Holocene ◽  
The Bohai Sea ◽  
Digital Elevation ◽  
Level Elevation ◽  
Elevation Model

AbstractGround-penetrating radar (GPR) reflection profiles were interpreted and combined with sedimentological data to highlight the morpho-evolutionary history of the southwestern sector of the Bohai Sea. The internal structures in GPR images obtained near the Holocene maximum transgression boundary revealed concave-upward and onlap types of transgressive paleotopography. The relationship between historical courses of the Yellow River and the distribution of shell ridges at three periods (6 ka, 2 ka, and recent times) showed that the concave-upward types derived from the marine sediments overlap the fluvial sediments, and the onlap types from the marine sediments cover the coastal lagoon sediments. Based on the above paleogeographical setting, previous sea-level markers were corrected, taking into account uncertainties of their relationship to former water levels. The rates of vertical tectonic displacement, evaluated through comparison of the relative sea level (RSL) data from the GPR images and the Holocene predicted sea-level elevation, markedly affected RSL changes. The fitted RSL curves from the corrected sea-level indicators showed that the accuracy of former sea-level determinations can be improved by comparing with the maximum transgressive position of GPR detection. A topographic digital elevation model (DEM) for 6 ka is reconstructed based on the corrected data.

scholarly journals New elevation data triple estimates of global vulnerability to sea-level rise and coastal flooding

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Scott A. Kulp ◽  
Benjamin H. Strauss
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
High Tide ◽  
Water Levels ◽  
Low Carbon ◽  
Digital Elevation ◽  
Elevation Data ◽  
Global Mean Sea Level ◽  
Elevation Model ◽  
Global Mean

Abstract Most estimates of global mean sea-level rise this century fall below 2 m. This quantity is comparable to the positive vertical bias of the principle digital elevation model (DEM) used to assess global and national population exposures to extreme coastal water levels, NASA’s SRTM. CoastalDEM is a new DEM utilizing neural networks to reduce SRTM error. Here we show – employing CoastalDEM—that 190 M people (150–250 M, 90% CI) currently occupy global land below projected high tide lines for 2100 under low carbon emissions, up from 110 M today, for a median increase of 80 M. These figures triple SRTM-based values. Under high emissions, CoastalDEM indicates up to 630 M people live on land below projected annual flood levels for 2100, and up to 340 M for mid-century, versus roughly 250 M at present. We estimate one billion people now occupy land less than 10 m above current high tide lines, including 230 M below 1 m.

Nutrients and heavy metals mediate the distribution of microbial community in the marine sediments of the Bohai Sea, China

2019 ◽  
Vol 255 ◽  
pp. 113069 ◽  
Author(s):  
Meiqing Lu ◽  
Xin Luo ◽  
Jiu Jimmy Jiao ◽  
Hailong Li ◽  
Xuejing Wang ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Microbial Community ◽  
Marine Sediments ◽  
Bohai Sea ◽  
The Bohai Sea

scholarly journals Glacial Isostatic Adjustment of the Laurentian Great Lakes Basin: Using the Empirical Record of Strandline Deformation for Reconstruction of Early Holocene Paleo-Lakes and Discovery of a Hydrologically Closed Phase*

2007 ◽  
Vol 59 (2-3) ◽  
pp. 187-210 ◽  
Author(s):  
C.F. Michael Lewis ◽  
Steve M. Blasco ◽  
Pierre L. Gareau
Keyword(s):  
Great Lakes ◽  
Response Surface ◽  
Lake Michigan ◽  
Vertical Motion ◽  
Water Levels ◽  
Early Holocene ◽  
Great Lakes Basin ◽  
Isostatic Adjustment ◽  
Digital Elevation ◽  
Elevation Model

Abstract In the Great Lakes region, the vertical motion of crustal rebound since the last glaciation has decelerated with time, and is described by exponential decay constrained by observed warping of strandlines of former lakes. A composite isostatic response surface relative to an area southwest of Lake Michigan beyond the limit of the last glacial maximum was prepared for the complete Great Lakes watershed at 10.6 ka BP (12.6 cal ka BP). Uplift of sites computed using values from the response surface facilitated the transformation of a digital elevation model of the present Great Lakes basins to represent the paleogeography of the watershed at selected times. Similarly, the original elevations of radiocarbon-dated geomorphic and stratigraphic indicators of former lake levels were reconstructed and plotted against age to define lake level history. A comparison with the independently computed basin outlet paleo-elevations reveals a phase of severely reduced water levels and hydrologically-closed lakes below overflow outlets between 7.9 and 7.0 ka BP (8.7 and 7.8 cal ka BP) in the Huron-Michigan basin. Severe evaporative draw-down is postulated to result from the early Holocene dry climate when inflows of meltwater from the upstream Agassiz basin began to bypass the upper Great Lakes basin.

Pathways of suspended sediments transported from the Yellow River mouth to the Bohai Sea and Yellow Sea

2020 ◽  
Vol 236 ◽  
pp. 106639 ◽  
Author(s):  
Xingmin Liu ◽  
Lulu Qiao ◽  
Yi Zhong ◽  
Xiuquan Wan ◽  
Wenjing Xue ◽  
...  
Keyword(s):  
Yellow Sea ◽  
Bohai Sea ◽  
Yellow River ◽  
River Mouth ◽  
Suspended Sediments ◽  
The Yellow River ◽  
The Bohai Sea ◽  
Yellow River Mouth

Water conservancy project on the Yellow River modifies the seasonal variation of Chlorophyll-a in the Bohai Sea

Chemosphere ◽  
2020 ◽  
Vol 254 ◽  
pp. 126846
Author(s):  
Xiaokun Ding ◽  
Xinyu Guo ◽  
Chao Zhang ◽  
Xiaohong Yao ◽  
Sumei Liu ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Chlorophyll A ◽  
Bohai Sea ◽  
Yellow River ◽  
The Yellow River ◽  
The Bohai Sea ◽  
Water Conservancy Project ◽  
Water Conservancy

scholarly journals Large-scale patterns in the community structure and biodiversity of freeliving nematodes in the Bohai Sea, China

2001 ◽  
Vol 81 (5) ◽  
pp. 755-763 ◽  
Author(s):  
Y. Guo ◽  
P.J. Somerfield ◽  
R.M. Warwick ◽  
Z. Zhang
Keyword(s):  
Community Structure ◽  
Environmental Variables ◽  
Large Scale ◽  
Bohai Sea ◽  
Yellow River ◽  
River Mouth ◽  
Sediment Surface ◽  
Similar Species ◽  
Taxonomic Distinctness ◽  
The Bohai Sea

Freeliving marine nematodes were sampled on two occasions from an extensive grid of 20 stations in the Bohai Sea and its approaches. Differences within stations between sampling periods were small, resulting from small changes in abundance of dominant species. Differences between stations were significant, and were used to cluster stations into groups with similar species composition. These station groupings revealed a weak faunal gradient leading from the mouth of the Huanghe (Yellow River) to the Bohai Strait. Analyses relating faunal composition to environmental variables showed that there were significant differences in environmental variables between faunally-defined groups of stations. The variables most closely correlated with community structure were silt/clay and sand, depth, phaeopigment concentrations below the sediment surface, organic content and arsenic. These reflect natural processes within the Bohai Sea. A suite of univariate measures were related to distance from the river mouth, with a major discontinuity about 120 km into the Bohai Sea. Comparison of values of the biodiversity measures average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) suggest that the meiobenthos of the Bohai Sea as a whole is not under major pollution stress.

Nutrient sources in the Bohai Sea and Yellow Sea: results from seasonal sampling in 2018

2020 ◽  
Author(s):  
Shichao Tian ◽  
Birgit Gaye ◽  
Jianhui Tang ◽  
Yongming Luo ◽  
Tina Sanders ◽  
...  
Keyword(s):  
Yellow Sea ◽  
Bohai Sea ◽  
Yellow River ◽  
The Yellow Sea ◽  
Reactive Nitrogen ◽  
Nutrient Concentrations ◽  
The Yellow River ◽  
Isotopic Ratios ◽  
Nutrient Sources ◽  
The Bohai Sea

<p>The Bohai Sea and Yellow Sea are semi-enclosed basins strongly affected by human activities due to climate change and growing industries in China. Changes of hydrology, nutrient concentrations and sources and resulting ecosystem responses are therefore progressively intensifying during the last decades. In order to characterize nutrient sources and dynamics and to estimate the anthropogenic impact, we investigated nutrient concentrations and dual isotopes of nitrate in spring and summer 2018 in Bohai Sea and Yellow Sea. Furthermore, we sampled suspended matter and surface sediments and determined organic carbon, nitrogen and stable nitrogen isotopic ratios.</p><p>In spring, the water column was well mixed and the study area was mainly affected by the Yellow River diluted water and the Yellow Sea Warm Current water, which were the main nitrate sources. In summer, the water was stratified, and the Yellow River and Changjiang River diluted water supplied nutrients to an even larger region than in spring. During this season, the Yellow Sea Cold Water mass formed the bottom water of the Yellow Sea where nutrients became enriched. In contrast to other polluted marginal seas, the stable isotopic ratios of dissolved and particulate nitrogen are relatively low in the study area, which could be due to nutrient supply from the atmosphere or the open ocean. Using nitrogen isotopes, we developed a box model of reactive nitrogen for the Bohai Sea and quantified the input of atmospheric and riverine reactive nitrogen, submarine groundwater and water exchange with the Yellow Sea, constraining the budgets of reactive nitrogen combining mass fluxes with an isotopic balance. Including the isotopic balance improved the mass balance based only on nutrient concentrations.</p>

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