Seventy-eight species and forms of testate amoebae were identified from 29 freshwater and soil habitats in three territories of China (Shandong and Hubei Provinces). Most abundant species from the genera
The impact of neotectonic activity on drainage system has been studied in a large alluvial fan in the eastern Himalayan piedmont area between the Mal River and the Murti River. Two distinct E–W lineaments passing through this area had been identified by Nakata (1972, 1989) as active faults. The northern lineament manifested as Matiali scarp and the southern one manifested as Chalsa scarp represent the ramp anticlines over two blind faults, probably the Main Boundary Thrust (MBT) and the Himalayan Frontal Thrust (HFT), respectively. The fan surface is folded into two antiforms with a synform in between. These folds are interpreted as fault propagation folds over the two north dipping blind thrusts. Two lineaments trending NNE–SSW and nearly N–S, respectively, are identified, and parts of present day courses of the Murti and Neora Rivers follow them. These lineaments are named as Murti and Neora lineaments and are interpreted to represent a conjugate set of normal faults. The rivers have changed their courses by the influence of these normal faults along the Murti and Neora lineaments and their profiles show knick points where they cross E–W thrusts. The overall drainage pattern is changed from radial pattern in north of the Matiali scarp to a subparallel one in south due to these conjugate normal faults. The interfluve area between these two rivers is uplifted as a result of vertical movements on the above mentioned faults. Four major terraces and some minor terraces are present along the major river valleys and these are formed due to episodic upliftment of the ground and subsequent downcutting of the rivers. The uppermost terrace shows a northerly slope north of the Chalsa scarp as a result of folding mentioned above. But rivers on this terrace form incised channels keeping their flow southerly suggesting that they are antecedent to the folding and their downcutting kept pace with the tectonism.
Since the 1990s, China has entered the middle phase of urbanization which leads to the existence of significant geographic concentration of agricultural land use. The average value of regional concentration degree of ten representative crops in China was 59.03%, showing a high degree of geographic concentration in farming. Some typical agriculture provinces in farming have arisen. The degree of geographic concentration in farming has been enhanced, with the average degree of regional concentration of ten crops increasing considerably by 3.83% in 2009 compared to that in 1990 (55.20%). The spatial growing center of farming was found to move westward and northward during 1990–2009. Meanwhile food production concentrated in the Northeast China and main producing area, and cash crops production concentrated in Northwest China. Off-farm employment of rural labor force, commercialization of agricultural product and regional comparative advantage are the main driving forces of geographic concentration of agricultural land use. Governmental policies with regional differences should be considered to promote further development of agriculture.
This study investigates the testate amoeba communities of a large peatland in Central China. The ecology and seasonal variability of testate amoeba communities were studied during 2009–2010. Investigation of environmental controls using ordination showed that the relationship between testate amoeba communities and depth to water table (DWT) and pH are extremely weak. The small proportion of variance explained by water table depth here (only 1.9% in the full data) shows that the hydrological control is weaker than we expected in this peatland, and weaker than any study we are aware of using a similar methodology. Attempts to develop species-environment (transfer function) models or identify indicator species for future palaeoecological studies were unsuccessful. Previous large-scale studies of peatland testate amoeba ecology have been largely restricted to Europe and North America and results have been relatively consistent among studies. Our results contrast with this consensus and suggest that at least in minerotrophic peatlands in China testate amoeba communities may be primarily controlled by different environmental variables. In China, testate amoebae have been relatively little studied but may prove to be valuable for a variety of applications in palaeoecology and biomonitoring and much further work is required.
Palaeochannels are deposits of unconsolidated sediments or semi-consolidated sedimentary rocks deposited in ancient, currently inactive river and stream channel systems. It is distinct from the overbank deposits of currently active river channels, including ephemeral water courses which do not regularly flow. We have introduced a spectral characteristics-based palaeochannel information extraction model from SPOT-5 imagery with special time phase, which has been built by virtue of an analysis of remote sensing mechanism and spectral characteristics of the palaeochannel, combined with its distinction from the spatial distribution and spectral features of currently active river channels, also with the establishment of remote sensing judging features of the palaeochannel in remote sensing image. This model follows the process of supervised classification → farmland masking and primary component analysis → underground palaeochannel information extraction → information combination → palaeochannel system image. The Zhegao River Valley in the east of Chaohu Lake was selected as a study area, and SPOT-5 imagery was used as a source of data. The result was satisfactory when this method has been successfully applied to extract the palaeochannel information, which can provide good reference for regional remote sensing archeology and neotectonic research. However, the applicability of this method needs to be tested further in other areas as the spatial characteristics and spectral response of palaeochannel might be different.
Five coticolous lichen samples were collected from western Hubei Province of China to analyze the long chain
The Snowball Earth hypothesis suggests that the sea water had totally been kept frozen for millions of years in Neoproterozoic glaciation, followed by a rapid and catastrophic deglaciation resulting from the elevated concentration of atmospheric CO2. However, the sedimentary records are not consistent with the Snowball Earth hypothesis. The Nantuo Formation in Three Gorges area is composed of diamictites, sandstones and siltstones. The geochronology and the unconformity with underlying Liantuo Formation indicate that the Nantuo Formation in Three Gorges area may be the partial record (i.e., the final stage) of the Nantuo glaciation. Our studies on sedimentary successions of the Nantuo Formation convince the stepwise transition from the Cryogenia icehouse to the Ediacaran greenhouse, in which multiple glacier advance-retreat cycles rather than a catastrophic termination could be identified.
Lipids in stalagmites have been shown the potential for the paleoclimate reconstruction. However, the low lipid content leads to the difficulty in gaining high resolution lipid record in stalagmites because large mass of samples are required. Previous studies have validated that the acid digestion can improve the yield of lipids, especially fatty acids (FAs) and 3-hydroxy fatty acids (3-OH-FAs). In order to obtain more content of FAs and 3-OH-FAs with limited stalagmite sample weight, we investigate here how the acid digestion conditions (HCl concentration, heating temperature and time duration) could affect the yields of FAs and 3-OH-FAs. Under different concentration of HCl, from 2.0 to 6.0 mol/L, the FAs keep the same step in content variation with 3-OH-FAs, and the highest yields of both two appeared under the 3 mol/L HCl. The content of 3-OH-FAs increases positively with the heating temperature from 80°C to 150°C, while FAs showed the highest content at 130°C. Both of FAs and 3-OH-FAs firstly increased to a high content and then decreased as the heating time duration varies from 1.0 to 4.0 h, with the highest yields of both two being at 3.0 h. Consequently, we suggest the optimized acid digestion condition is under 3 mol/L HCl, heating at 130°C for 3 h and 5 g of each stalagmite sample are sufficient for the lipid analysis.