Using 110 newly revised Holocene sea level indicators categorized into three types,sediments(67),shelly cheniers(27)and oyster reefs(16),this paper firstly provides a Holocene relative sea level curve,based on multipl...Using 110 newly revised Holocene sea level indicators categorized into three types,sediments(67),shelly cheniers(27)and oyster reefs(16),this paper firstly provides a Holocene relative sea level curve,based on multiple approaches of litho-and biostratigraphies and sedimentary faces analysis,for the west coast of Bohai Bay,China.Following considerations,including indicative meaning,the paleo tidal pattern and range and conversion from mean tidal level to mean sea level,an apparent relative mean sea level(RMSL)curve was further reconstructed.After systematical calibration using CALIB,those of the 48 reworked samples were further corrected for the residence-time effect.Similarly,the younger ages for another 35 samples were chosen at the subsample level.These result in a younger-oriented shift for about 0.5 ka.Three local spatial factors,including neotectonic subsidence(average rate about 0.1 mm/a),self-compaction of unconsolidated sediments(between a few decimeters to about 6 m)and subsidence due to groundwater withdrawal(between a few centimeters to about 2.5 m),were quantitatively corrected.Finally,the amended RMSL curve after eliminating all these local temporo-spatial factors is very likely to show non-existence of mid-Holocene highstand and imply potential influences of both ice-volume equivalent sea level and regional glacial isostatic adjustment.Although it is still unable to divide both global and regional factors,the slowdown of sea level rise,in 7.5–6.8 ka with a maximum height less than+1 m,may constrain the model effort in the near future.展开更多
Ordos is located in the western part of North China Platform and was subjected to erosion at the late stage of Caledonian movement when the platform was uplifted. Later, Variscian movement made this region subside and...Ordos is located in the western part of North China Platform and was subjected to erosion at the late stage of Caledonian movement when the platform was uplifted. Later, Variscian movement made this region subside and the paleo-North China Sea and Qilian Sea transgressed onto Ordos, from both the east and west sides during the展开更多
A key step towards the restoration of heavily disturbed fragile coastal wetland ecosystems is determin- ing the composition and characteristics of the plant communities involved. This study determined and char- acteri...A key step towards the restoration of heavily disturbed fragile coastal wetland ecosystems is determin- ing the composition and characteristics of the plant communities involved. This study determined and char- acterized the community of higher plants in the Chenier wetland of Bohai Bay using a combination of field surveys, quadrat approaches, and multivariate statistical analyses. This community was then compared to other adjacent wetlands （Tianjin, Qinhuangdao, Laizhouwan, Jiaozhou- wan, and Yellow River Delta wetland） located near the Huanghai and Bohai Seas using principal coordinate analysis （PCoA）. Results showed a total of 56 higher plant species belonging to 52 genera from 20 families in Chenier wetland, the majority of which were dicotyledons. Single-species families were predominant, while larger families, including Gramineae, Compositae, Leguminosae, and Chenopodiaceae contained a higher number of species （cache〉6 species）. Cosmopolitan species were also dominant with apparent intrazonality. Abundance （number of species） of temperate species was twice that of tropical taxa. Species number of perennial herbs, such as Gramineae and Compositae, was generally higher. Plant diversity in the Chenier wetland, based on the Shannon- Wiener index, was observed to be between the Qinhuang- dao and Laizhouwan indices, while no significant difference was found in other wetlands using the Simpson index. Despite these slight differences in diversity, PCoA based on species abundance and composition of the wetland flora suggest that the Bohai Chenier community was highly similar to the coastal wetlands in Tianjin and Laizhouwan, further suggesting that these two wetlands could be important breeding grounds and resources for the restoration of the plant ecosystem in the Chenier wetland.展开更多
基金The National Natural Science Foundation of China under contract Nos 41372173,41476074 and 41806109the China Geological Survey Project under contract Nos DD20189506 and DD20211301.
文摘Using 110 newly revised Holocene sea level indicators categorized into three types,sediments(67),shelly cheniers(27)and oyster reefs(16),this paper firstly provides a Holocene relative sea level curve,based on multiple approaches of litho-and biostratigraphies and sedimentary faces analysis,for the west coast of Bohai Bay,China.Following considerations,including indicative meaning,the paleo tidal pattern and range and conversion from mean tidal level to mean sea level,an apparent relative mean sea level(RMSL)curve was further reconstructed.After systematical calibration using CALIB,those of the 48 reworked samples were further corrected for the residence-time effect.Similarly,the younger ages for another 35 samples were chosen at the subsample level.These result in a younger-oriented shift for about 0.5 ka.Three local spatial factors,including neotectonic subsidence(average rate about 0.1 mm/a),self-compaction of unconsolidated sediments(between a few decimeters to about 6 m)and subsidence due to groundwater withdrawal(between a few centimeters to about 2.5 m),were quantitatively corrected.Finally,the amended RMSL curve after eliminating all these local temporo-spatial factors is very likely to show non-existence of mid-Holocene highstand and imply potential influences of both ice-volume equivalent sea level and regional glacial isostatic adjustment.Although it is still unable to divide both global and regional factors,the slowdown of sea level rise,in 7.5–6.8 ka with a maximum height less than+1 m,may constrain the model effort in the near future.
文摘Ordos is located in the western part of North China Platform and was subjected to erosion at the late stage of Caledonian movement when the platform was uplifted. Later, Variscian movement made this region subside and the paleo-North China Sea and Qilian Sea transgressed onto Ordos, from both the east and west sides during the
文摘A key step towards the restoration of heavily disturbed fragile coastal wetland ecosystems is determin- ing the composition and characteristics of the plant communities involved. This study determined and char- acterized the community of higher plants in the Chenier wetland of Bohai Bay using a combination of field surveys, quadrat approaches, and multivariate statistical analyses. This community was then compared to other adjacent wetlands （Tianjin, Qinhuangdao, Laizhouwan, Jiaozhou- wan, and Yellow River Delta wetland） located near the Huanghai and Bohai Seas using principal coordinate analysis （PCoA）. Results showed a total of 56 higher plant species belonging to 52 genera from 20 families in Chenier wetland, the majority of which were dicotyledons. Single-species families were predominant, while larger families, including Gramineae, Compositae, Leguminosae, and Chenopodiaceae contained a higher number of species （cache〉6 species）. Cosmopolitan species were also dominant with apparent intrazonality. Abundance （number of species） of temperate species was twice that of tropical taxa. Species number of perennial herbs, such as Gramineae and Compositae, was generally higher. Plant diversity in the Chenier wetland, based on the Shannon- Wiener index, was observed to be between the Qinhuang- dao and Laizhouwan indices, while no significant difference was found in other wetlands using the Simpson index. Despite these slight differences in diversity, PCoA based on species abundance and composition of the wetland flora suggest that the Bohai Chenier community was highly similar to the coastal wetlands in Tianjin and Laizhouwan, further suggesting that these two wetlands could be important breeding grounds and resources for the restoration of the plant ecosystem in the Chenier wetland.
