Environmental magnetic properties of core sediments in the Yellow River subaqueous delta and their chronological applications

Chen, Ting1; Liu, Qingsong2,3; Zheng, Yi4

2021

10.1360/TB-2021-0528

Chinese Science Bulletin-Chinese   影响因子和分区

0023-074X

2095-9419

["The Yellow River has shifted frequently in the downstream region since 1885; it has flowed into the sea through the Qingshuigou channel from 1976 onward, thus forming the latest delta lobe (1976-present). During the past similar to 40 years, the sediment load of the Yellow River has been greatly reduced because of human and natural activities, such as reservoir construction, soil and water conservation, and river avulsion. Beginning in 2002, the water-sediment regulation scheme (WSRS) has also changed the sediment loading patterns of the Yellow River. Several studies have reported on the erosion and deposition characteristics of the latest lobe of the Yellow River Delta over the past several decades, based on remote sensing methods and water-depth measurements. However, continuous sedimentary records of delta erosion and deposition and their responses to natural and human activities in the watershed are lacking. Here, we obtained three sediments cores, YD01, YD02, and YD03, from the subaqueous delta of the latest lobe of the Yellow River Delta. These cores contain sediments deposited from 1976 to 2018. We analyzed the environmental magnetism and lithological characteristics of these cores, and investigated their responses to natural and human activities in the watershed of the Yellow River, as well as possible applications to sediment dating in the Yellow River Delta. The results show that frequency-dependent susceptibility (chi(fd)%) and anhysteretic remanent magnetization susceptibility (chi(ARM)) values were high in core sediments deposited from 1976 to 1996, indicating abundant contents of fine single-domain (SD) and superparamagnetic (SP) magnetic particles, and therefore a dominant sediment supply from the Chinese Loess Plateau. Small decreases in chi(fd)% and chi(ARM) in sediments deposited after 1986 revealed slight reduction of the sediment load from the Yellow River, which was likely caused by sediment retention related to the construction of the Longyangxia Reservoir. Rapid rises in chi(fd)% and chi(ARM) occurred in core YD01 sediments deposited during 2002 and similar to 2007, likely in response to the implementation of the WSRS, which resulted in an increase in sediment transportation. Increases in hard isothermal remanent magnetization (HIRM) values, an indicator of high-coercivity magnetic minerals such as goethite and hematite, in cores YD02 and YD03 from 2002 to similar to 2007 may also represent the start of the WSRS. This is because the downstream riverbed of the Xiaolangdi Reservoir underwent intense erosion during the implementation of the WSRS, leading to large-scale transportation of coarse sediments enriched in goethite and hematite, which were deposited on the riverbed before the implementation of the WSRS. The lack of increased contents of fine SD and SP magnetic minerals in cores YD02 and YD03 compared with YD01 in the interval deposited between 2002 and similar to 2007 was attributed to erosion and redeposition in the areas around cores YD02 and YD03. Large drops in SD and SP contents after similar to 2007 were detected in all three cores, revealing intense erosion near the river mouth likely caused by river channel shift and reduced capability of the WSRS to remove sediments. Contents of SD and SP particles increased again in sediments deposited after 2014 in cores YD02 and YD03, likely related to erosion of the present (after 1996) Yellow River mouth and transportation of fine particles to the region near cores YD02 and YD03.","In summary, the magnetic parameters chi(fd)% and chi(ARM) and the lithological characteristics of cores YD01, YD02, and YD03 recorded sediment delivery changes caused by four events in the Yellow River watershed: The main river channel shift in 1976, construction of the Longyangxia Reservoir in 1986, the beginning of the WSRS in 2002, and weakened capability of the WSRS to remove sediments after similar to 2007. The notable changes of chi(fd)%, chi(ARM), and lithology at the 1976, 1986, 2002, and similar to 2007 horizons may be used as dating points in future research of sediment cores from the Yellow River Mouth."]

the Yellow River Delta water-sediment regulation scheme environmental magnetism the Yellow River channel shifts sediment sources

ESCI ; EI

中文

通讯

Science & Technology - Other Topics

Multidisciplinary Sciences

WOS:000715757500012

SCIENCE PRESS

20214611154163

Coercive force ; Deposition ; Environmental regulations ; Erosion ; Hematite ; Lithology ; Magnetization ; Remote sensing ; Reservoirs (water) ; Rivers ; Water conservation ; Watersheds

Reservoirs:441.2 ; Water Resources:444 ; Surface Water:444.1 ; Environmental Impact and Protection:454.2 ; Geology:481.1 ; Minerals:482.2 ; Soil Mechanics and Foundations:483 ; Magnetism: Basic Concepts and Phenomena:701.2 ; Chemical Operations:802.3

Web of Science

1.Chongqing Normal Univ, Chongqing Key Lab Earth Surface Proc & Environm R, Chongqing 401331, Peoples R China
2.Southern Univ Sci & Technol, Ctr Marine Magnetism, Dept Ocean Sci & Engn, Shenzhen 518055, Peoples R China
3.Southern Marine Sci & Engn Guangdong Lab Guang Ho, Guangzhou 511458, Peoples R China
4.Southern Univ Sci & Technol, Sch Environm Sci & Engn, Shenzhen 518055, Peoples R China

Chen, Ting,Liu, Qingsong,Zheng, Yi. Environmental magnetic properties of core sediments in the Yellow River subaqueous delta and their chronological applications[J]. Chinese Science Bulletin-Chinese,2021,66(30):3902-3915.

Chen, Ting,Liu, Qingsong,&Zheng, Yi.(2021).Environmental magnetic properties of core sediments in the Yellow River subaqueous delta and their chronological applications.Chinese Science Bulletin-Chinese,66(30),3902-3915.

Chen, Ting,et al."Environmental magnetic properties of core sediments in the Yellow River subaqueous delta and their chronological applications".Chinese Science Bulletin-Chinese 66.30(2021):3902-3915.