Spatial variation of diatom diversity with water depth at Huguang Maar Lake, Southern China

2021 ◽  
Author(s):  
Jingjing Li ◽  
Luo Wang ◽  
Yafei Zou ◽  
Jie Li
Keyword(s):  
Spatial Variation ◽  
Water Depth ◽  
Southern China ◽  
Maar Lake

Spatial variation in morphology of the White-browed Laughingthrush (Garrulax sannio) and its relationship with climate conditions in southern China

2020 ◽  
Vol 161 (3) ◽  
pp. 701-711
Author(s):  
Longying Wen ◽  
Janine M. Antalffy ◽  
Kevin Messenger ◽  
Wei Zhao ◽  
Fangqing Liu ◽  
...  
Keyword(s):  
Spatial Variation ◽  
Southern China ◽  
Climate Conditions

High-resolution Geomagnetic Field Records Decipher the Possible Precession links since about 340-kyr in a maar lake sediment sequence in tropical Asia

2020 ◽  
Author(s):  
Xiaoqiang Yang ◽  
Cong Chen ◽  
Zhuo Zheng
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Geomagnetic Field ◽  
Southern China ◽  
Singular Spectrum Analysis ◽  
Luminescence Dating ◽  
Large Spatial Scale ◽  
The Earth ◽  
Earth Magnetic Field ◽  
Maar Lake

<p>A series of paleomagnetic works relying on the ocean sediments present some significant astronomic periods, such as a 100 kyr quasi-period and 41 kyr obliquity signal. These studies provide the new insights unscrambling what and how the earth magnetic field changed in despite of the ongoing debating. Numerical studies of recent years also reveal the possibility of the precession drive the dynamos and influence the magnetic field. However, the less of reliable high-resolution paleomagnetic records besides of relative paleointensity reduce its credibility. Here, we present some detailed rock magnetic and paleomagnetic studies on the continuous 40-m-thick sediments in two parallel cores retrieved from Tianyang Maar lake, southern China. The new results would contribute to discuss the correlation of paleomagnetic field with the astronomical factors.</p><p>Tianyang Maar lake  is located in the southern part of the Leizhou Peninsula.  The maar lake has a surface area of ~ 7.3 km<sup>2</sup> surrounded by a 40 - 60 m high crater rim composed of basaltic breccia and tuff . Two new parallel cores, TY08 and TY15 (~ 10 m apart), were extracted from center of the crater in 2008 and 2015, respectively, using a rotary borer consisting of a stainless steel outer tube and a plastic inner tube to minimize sediment disturbances and contamination. The sediments of two cores can divided into three zones: about upper 15.59 m was composed of varying colors clay and the middle part (15.59-21.94 m), was dominated by the grey and greyish-brown fine to coarse sand with occasional gravels, embedded a thick grey clay layer; the lower part (21.94-40.0 m) shown as the dark grey and black organic-rich clay.</p><p>The paleomagnetic results show that the natural remanent magnetization (NRM) of the sediments is mainly contributed by magnetically soft minerals, and the sediments have fairly documented geomagnetic field variations. A chronology is constructed using multiple methods, including radiocarbon dating, optically stimulated luminescence dating and terrestrial-marine pollen correlation. The 340-kyr paleomagnetic inclination record displays patterns similar to those seen in regional records over a large spatial scale (> 3000 km), implying that these records may reflect large-scale core dynamics on timescales of 10<sup>4 </sup>- 10<sup>5</sup> years in this low-latitude region. The Tianyang inclination record exhibits a negligible inclination anomaly (∆I = -0.08°) and features six anomalous inclination events, which are assigned to the Laschamp, Blake, Fram Strait II/6α, Iceland Basin, Mamaku and 9α excursions respectively. The spectral and singular spectrum analysis (SSA) exhibit that the inclination does not show the significant signal of 100-kyr periodicity, however, the closed precession period is obvious in the third components of inclination (PC3). PC3 component shows nearly synchronous variations with the precession parameter while the opposite correlation appeared under the condition of eccentricity minima strong. This corresponding pattern hint us that astronomical parameters have the essential influence to the earth magnetic field, however, the different moving may forc or constrain the earth magnetic behavior.</p>

Vegetation and climate changes over the last 30 000 years on the Leizhou Peninsula, southern China, inferred from the pollen record of Huguangyan Maar Lake

Boreas ◽  
2017 ◽  
Vol 46 (3) ◽  
pp. 525-540 ◽  
Author(s):  
Yuting Meng ◽  
Weiming Wang ◽  
Jianfang Hu ◽  
Jixiao Zhang ◽  
Yangjun Lai
Keyword(s):  
Climate Changes ◽  
Southern China ◽  
Pollen Record ◽  
Leizhou Peninsula ◽  
Maar Lake ◽  
Vegetation And Climate ◽  
Huguangyan Maar Lake

scholarly journals Study on the Density, Hydrostatic Setting Velocity and Locomotion of Biomphalaria Straminea

2021 ◽  
Author(s):  
Fengyang Min ◽  
Jiasheng Wang ◽  
Shizhu Li ◽  
Jiazhou Chen ◽  
Xingjian Xu ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Water Depth ◽  
Neglected Tropical Diseases ◽  
Southern China ◽  
Bottom Layer ◽  
Average Density ◽  
Dispersal Capacity ◽  
Biomphalaria Straminea ◽  
Significant Difference ◽  
Water Conservancy

Abstract [Background]Schistosomiasis mansoni is one of the most prevalent neglected tropical diseases transmitted by snails of the genus Biomphalaria . The pla norbid freshwater snail Biomphalaria straminea as an invasive vector is expanding its geographic range for its great dispersal capacity in Gonuangdong Province, causing potential risk of an epidemic of S. mansoni in southern China . Previous studies have mainly focus ed on the environmental factors that affect B straminea’ s distribution, but few studies have looked at its hydraulic characteristics for the water conservancy control. This stud y explored its primary parameters of the hydraulics characteristic s including density, hydrostatic setting velocity and l ocomotion in different water depth to evaluate its peculiar dispersion characteristics in natural environment. [Methods] The density and hydrostatic setting velocity of B. stramine were measured by the drainage volume method and setting tube method, respectively. T he behavior and distribution characteristics of B. stramine in different water depths were observed by the Plexiglas tube method and the effect s of hydrostatic pressure on the climbing speed of B. stramine were also analyzed. [Results] Our results show that the average density of the B. stramine is 1.08 g/cm 3 . The hydrostatic setting velocity of B. stramine is between 2.32 cm/s and 12.92 cm/s in the water , there is no significant difference betwe en the settling velocity and their shape type. In the Plexiglas tubes with different depths, we noted that the locomotion can occur in six manners. The B. stramine distribute mainly along the surface and at the bottom layer of the tubes and the proportion of the B. stramine on the surface water generally raised as time increase d. Also, we observed the climbing speed of B. stramine at different water depth, and obtained the regression equation of the hydrostatic pressure and their climbing speed of the B. stramine . It revealed that the climbing speed of B. stramine increases first and then decreases with the water depth increase, and reaches the maximum when the water depth at 120cm. [Conclusion] The findings of this study indicate that there are si gnificant differen ces between the 50 density , the hydrostatic setting velocity and climbing speed of B. stramine compared with 51 Oncomelania hupensis . Future studies should be conducted more intensive on h ydraulics 52 characteristics of B . straminea and thus establish adequ ate water conservancy measures to control 53 its dispersion

Paleoenvironmental shifts and precipitation variations recorded in tropical maar lake sediments during the Holocene in Southern China

The Holocene ◽  
2014 ◽  
Vol 24 (10) ◽  
pp. 1216-1225 ◽  
Author(s):  
Xiaoqiang Yang ◽  
Gangjian Wei ◽  
Jie Yang ◽  
Guodong Jia ◽  
Chenchen Huang ◽  
...  
Keyword(s):  
Lake Sediments ◽  
Southern China ◽  
The Holocene ◽  
Maar Lake

The early Holocene optimum inferred from a high-resolution pollen record of Huguangyan Maar Lake in southern China

2007 ◽  
Vol 52 (20) ◽  
pp. 2829-2836 ◽  
Author(s):  
ShuYun Wang ◽  
HouYuan Lü ◽  
JiaQi Liu ◽  
Jörg F. W. Negendank
Keyword(s):  
High Resolution ◽  
Southern China ◽  
Early Holocene ◽  
Pollen Record ◽  
Maar Lake ◽  
Huguangyan Maar Lake

scholarly journals A Holocene palaeomagnetic secular variation record from Huguangyan maar Lake, southern China

2012 ◽  
Vol 190 (1) ◽  
pp. 188-200 ◽  
Author(s):  
Xiaoqiang Yang ◽  
Qingsong Liu ◽  
Zongqi Duan ◽  
Zhihua Su ◽  
Gangjian Wei ◽  
...  
Keyword(s):  
Secular Variation ◽  
Southern China ◽  
Maar Lake ◽  
Huguangyan Maar Lake
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