Meteorological observation data is the basis of climate change research. Detection and correction of homogeneity of meteorological data can improve the precision and accuracy of the climate change research. Based on the monthly mean temperature data from 65 meteorological stations over the Tibetan Plateau and the surrounding areas from 1961-2010, detection and correction of homogeneity of temperature series were carried out by using the PMFT method. The results show that condition of homogeneity of mean air temperature data over the Tibetan Plateau is poor. There are 32 detected stations, accounting for 49% of the total, at least having one breakpoint. The adjusted temperature data is homogeneity. Analyzing the data found that the annual mean temperature had risen with a rate of 0.32 ℃·(10a)-1 in the Tibetan Plateau from 1961-2010; the seasonal warming rates over the Tibetan Plateau had been 0.24, 0.26, 0.32 and 0.48 ℃·(10a)-1 for spring, summer, autumn and winter, respectively, slightly smaller than the results obtained by using the original data. The study also found that the data homogeneity or not has little effect on the analysis result of climate change for the plateau as a whole, but has much effect on the result for part of the plateau. Spatially, climate change in the Tibetan Plateau is very different from one area to another area. Therefore, for researching the difference of the climate change over the Tibetan Plateau in the future, detection and correction of homogeneity of meteorological data is particularly necessary. The metadata from meteorological station plays an important role in the process of the climate data homogeneity test and correction, which may provide basical information that affect climate sequence homogeneity, such as the changing site, observation time, method and instrument, and provides reference for analysis, inspection and correction of climate data sequence. In order to improve the accuracy of data homogeneity test, it is necessary to strengthen the study of climate data homogeneity test technique in the future and as far as possible to collect more detail metadata.
A 293-year, annually-resolved ice core record from LGB69, Princess Elizabeth Land, East Antarctica, is used to investigate the atmospheric circulation variability over the mid- to high-latitude southern Indian Ocean (SIO). The first EOF (EOF1) of chemical ions in the LGB69 ice core is indicative of changes in both mean sea level pressure and the low level wind fields over the SIO. Changes in sea-salt record (also EOF1) are strongly correlated with the SIO low (r=-0.4, P<0.1) and the zonal westerlies (r=0.5, P<0.02), with the highest correlation occurring in austral autumn (March to May) probably due to the effects of the semiannual oscillation. Changes in EOF1 are also strongly correlated with meridional inland wind, with the highest correlation (r=-0.4, P<0.1) found during austral summer (December to February) when katabatic winds prevail in coastal Antarctica. Further analysis indicates that the Na+ records were negatively correlated with the Southern Annular Mode (SAM) during the period 1850 to 1970, but positively correlated during the period 1971 to 2001 in correspondence to the shifted SAM phase. Additionally, the 3.5 years periodicity of the Na+ records, which occurred discontinuously from 1708 to 2001, shows good coherence with the periodicity of the SAM index series.
Based on monthly temperature and precipitation grid datasets from CRU (Climatic Research Unit), APHRODITE (Asian Precipitation: Highly-Resolved Observational Data Integration Towards Evaluation) and CMIP5 (Coupled Model Inter-comparison Project phase 5) models, the simulation ability of CMIP5 models in the Indus River Basin (IRB) is evaluated for the period 1961-2005. For improving the simulation ability, the systematic bias between CMIP5 and CRU/APHRODITE is corrected by the equidistant CDF matching method (EDCDFm) firstly and then the possible change of climate change is estimated in the IRB during 2046-2065 and 2081-2100 subsequently. The results show that the CMIP5 multi-model ensemble can capture the temporal variation and the spatial distribution characteristics of annual mean temperature quite satisfactory, with temporal and spatial correlation between the CMIP5 and CRU reaching the significant level of 0.01, and summer temperature simulation results are obviously better than other months. On the other hand, CMIP5 ensembles can also reproduce seasonal variation of precipitation quite well. Based on the bias-corrected results, it is estimated that the annual averaged temperature over the whole basin will continuously increase under Scenarios RCP2.6, 4.5, 8.5 during 2046-2065 and 2081-2100 relative to those during 1986-2005, with the maximum increasing scope in the upstream areas. Annual precipitation will also increase with the exception of weak decrease during mid-21st century under Scenario RCP4.5. The persistently rising of summer temperature might cause further glacier ablation, and impact the local freshwater availability. The contribution of spring precipitation to water resources in the middle and high altitude areas will decrease. Increase in precipitation in northern high altitude areas will be favorable to glacier accumulation and increase water resources, while the decreasing precipitation in eastern high altitude areas will reduce water resources. Summer precipitation almost increases over the whole basin during both mid and late 21st century. The risk of flood disasters will increase. It is estimated that warm events and heavy rainfall events may increase in the Indus River Basin as well.
Land surface temperature (LST) is a crucial parameter of surface energy budget and controls the thermal regime of the active layer in permafrost regions. However, there are limited observed datasets available for the Tibetan Plateau, with greater bias in the LST products from remote sensing data. In this study, the LST calculated with the upward and downward long-wave radiation data from the three automatic weather stations were compared with the MODIS LST products. Meanwhile, the LST retrieved from Landsat 5 TM and Landsat 7 ETM+ was also compared with MODIS LST to explain the consistency between remote sensing data with different resolutions. In daytime, the mean absolute error (MAE) and the root-mean-square error (RMSE) of MODIS LST products were about 3.42~4.41 ℃ and 4.41~5.29 ℃, respectively. In nighttime, the MAE and the RMSE of MODIS LST products were about 2.15~2.9 ℃ and 3.05~3.78 ℃, respectively, indicating that the nighttime MODIS LST have a better accuracy. Both of the LSTs retrieved from TM and ETM+ have a good consistency with MODIS LST, with the correlation coefficients of greater than 0.85 and 0.95 for TM and ETM+, respectively. MODIS LST products have a high applicability in continuous permafrost regions in the Tibetan Plateau, which is a potential dataset for monitoring permafrost thermal regime. The consistency between Landsat TM/ETM+ LST and MODIS LST is also high. The results can be used to monitor and model permafrost with remote sensing data of multi-sources
Three tree-ring width chronologies were established by using the samples of Sabina przewalskii from the timberlines in the Middle Qilian Mountains. Correlation analysis and response analysis showed a significant negative correlation between tree-ring width and snow depth or snow cover area. After identifying the relationship between snow depth and tree growth, the maximum snow depth in September in the previous year is able to be reconstructed using tree-ring width data. The reconstruction reflects the snow depth variation well. And there have been three high snow depth periods in the study area in the last 270 years: 1740-1780, 1825-1880 and 1910-1980. Moreover, in the long term, variation of snow depth keeps pace with glacier variation in the Qilian Mountains and other parts of western China. In addition, snow depth has an obvious negative relationship with temperature.
Based on the simulated net primarily production (NPP) from CMIP5, the spatial-temporal characteristics of NPP at the mid-high latitude of Northern Hemisphere landmass for three Representative Concentration Pathways (RCP2.6, RCP4.5, RCP8.3) during the early (2016-2035), middle (2046-2065) and late (2080-2099) periods of the 21st century are estimated. Combined with climatic factors, the relation between NPP and temperature, precipitation and surface shortwave radiation is also discussed. The results show that, relative to the reference period of 1986-2005, NPP at the mid-high latitude of Northern Hemisphere will represent an increasing trend during the 21st century, and the increase of NPP under RCP8.5 is greater than that under RCP2.6 and RCP4.5. As regards seasonal change, NPP at the mid-high latitude of Northern Hemisphere also shows an increasing trend, and the most obvious change of NPP appears in summer, especially in June. Furthermore, the response of NPP to climate change varies regionally. Relative to 1986-2005, for the middle and low scenarios (RCP2.6, RCP4.5), the range of significant impact of temperature on NPP at the mid-high latitude of Northern Hemisphere during the 21st century will gradually go down, while that of radiation and precipitation will expand. Under RCP8.5, the change of NPP at the mid-high latitude of Northern Hemisphere during the 21st century will essentially depend on temperature.
Glacier mass balance is regarded as the bridge and tie between the meteorology and water resources in glaciated regions, so monitoring and simulating mass balance is always one of the frontier research topics. A physical energy-balance model and four statistical degree-day factor models based upon temperature-index, radiation-index and temperature-radiation-vapor-index are presented, in which the Shiyi Glacier is taken as a case of study. The results are deeply analyzed and evaluated. When the degree-day factor model is enhanced by net shortwave radiation index, resulting in 90% of the ablation rate, the model will be improved significantly. The enhanced day-degree factor model combining with shortwave radiation and water vapor becomes the best model amongst all models. The results of energy/mass balance models suggest that net radiation is the dominant energy source to the glacier surface, accounting for 82.3% of all the inward fluxes, followed by the sensible heat flux, accounting for 17.7%of all the inward fluxes. The long wave radiation is mostly negative one during the modeling period. The ablation energy and latent heat flux account for 84.7% and 15.3% of the heat loss. The relative error of the radiation-vapor day-degree model is 7%, which is slightly higher than that in energy-balance model, 6.7%. Comparison suggests that the energy-balance model is more capable of modeling the value and the amplitude of variation, especially in daily scale. Likewise the statistical models perform insufficiently, especially, to the local specific topography. However, the statistical models require few input data, with computational simplicity. This study will be useful for establishing glacier mass-balance model in the Heihe River Basin and the Qilian Mountains.
The stable isotope (δ18O) on the Tibetan Plateau was interpolated by Cressman interpolation method and by optimum interpolation method after altitude correction. It is found that the performance of the optimum interpretation method is better than that of the Cressman interpretation method. Comprised with the results of regression model (BW model), the spatial distribution of δ18O interpolated by optimum interpretation method is also better. In the meanwhile, the δ18O spatial distribution on the southern Tibetan Plateau has been obviously improved through an altitude correction. However, the δ18O spatial distribution on the northern Tibetan Plateau has not been better after altitude correction.
Based on the reanalyzed data of ERA-Interim daily 600 hPa geopotential height and the daily mean temperature, precipitation and humidity data from 75 meteorological stations over the Tibetan Plateau and its adjacent regions, seasonal variations of pressure systems in surface layer and northern regions over the Tibetan Plateau were analyzed. The results indicated that the intensities of pressure systems in surface layer and northern regions will constantly strengthen when the system rotates clockwise surround a center and will constantly weaken when the system rotates anti-clockwise surround a center. At 600 hPa, pressure system strengthens in surface layer but weakens in northern Tibetan Plateau. The height gradient points from north to south as the plateau summer monsoon starting and points from south to north as the plateau summer monsoon ending. The starting and ending times of plateau summer precipitation are not only closely related to pressure systems in surface layer over the plateau and its northern regions, but also closely related to water vapor transport in the southeast and south Tibetan Plateau.
Based on the hourly precipitation data from four stations over the Yili River Valley during 2007-2011, the daily variation characteristics of summer precipitation were analyzed. The results showed that the maximum precipitation appears at 22:00 Beijing Time (BT), and the minimum precipitation appears at 13:00 (BT), mainly concentrating in between 21:00 and 08:00 (BT). The maximum precipitation frequency occurs in between 23:00 and 10:00 (BT), with the maximum value at 03:00 (BT) and the minimum value at 16:00 (BT). The maximum precipitation intensity generally appears at 16:00 (BT) and the minimum one occurs at 13:00 (BT). There is short-term precipitation frequently over the Yili River Valley, mostly with the time less than one hour. The precipitation events of 2-hour have most contribution to the total precipitation, and the precipitation events of 14-hour have least contribution to the total precipitation. The summer precipitation over the Yili River Valley mostly occurs at night, with short-term precipitation events frequently.
Based on the daily precipitation, temperature and geopotential high data in spring from 1961 to 2013, the series of precipitation, air temperature and meteorological drought index were calculated. Then after analyzing the characteristics and cause of sudden turn of drought and flood with the climate diagnosis methods. It is summarized as follows: from 2013.3.1 to 2013.4.27 greater part of the province had less rainfall and higher temperature, and then appeared a large range meteorological drought with different degree, and in greater part of Xining and Haibei appeared the meteorological drought with frequencies of 1-in-25 years and 1-in-50 years, respectively. Then from 2013.4.28 to 5.20 greater part of the province had more rainfall, and the higher temperature shifted to lower one gradually, so the drought relieved and waterlogging appeared in a large range with different degree. There were 21 stations had the records of sudden turn of drought and flood. Composition analysis shows that when the polar vortex area is smaller than ordinary, the central and west Asia trough has longer duration, the cold air cumulates in eastern Europe and western Asia regions, the cold air into China inclines to the west, the plateau potential height field inclines to low, the east Asian trough inclines to east and the western Pacific subtropical high inclines to north, Qinghai Province will have more precipitation and more prone to waterlogging, and vice versa. The drought in April and the waterlogging in May is under the climate background of long-term variation in Qinghai plateau, characterized by the Tibetan Plateau surface heating field with high intensity in the early stage of January to March. The transient time from spring to summer in advance will be conducive to abnormal precipitation in May in the province.
In this paper, based on the data from seven representative weather stations in Altay Prefecture from 1961 to 2012, the daily minimum air temperature data were studied by using trend coefficient, Morlet wavelet transformation and correlation analysis. Thus, the variation of cold wave was analyzed. It is found that the cold wave frequency was about two times of the number of strong cold wave. The monthly variation of cold waves had a unimodal type, concentrating in between November and the next February, but less occurring in between September and May. In the last 52 years, the numbers of cold wave and strong cold wave have decreased slightly. The anomaly series of cold wave shows multi-time scale structure and appears decadal variation. Correlation analysis demonstrates that there is significant correlation between cold wave duration and the characteristic quantity of atmospheric circulation in Altay Prefecture.
In this paper, the information of ozone amounts derived from ground-based and space-based observations are investigated through a comparison of the ozone amounts from ground-based and three satellite products over Lhasa during 2008-2012. It is found that the absolute difference of ozone amounts between ground and space-based observations varies from -10 to 15 DU, while the relative difference varies from -4% to 4%, fitting the normal distribution of 0.05 significance. Compared with the ground-based observation, the precision of SCIAMACHY (TOSOMI) ozone amount is the best and the precision of OMI (DOAS) ozone amount is the worst. The standard deviation of ozone amount between ground and space-based observations exists obviously seasonal variation, while the deviation is the largest in summer and smallest in winter. The data discrepancy between ground-based and space-based ozone amounts increases with cloudy impact, especially for the ozone amount from SCIAMACHY (TOSOMI).
Datong Basin is located in an edge of East Asian monsoon zone, North China, and is characterized by a fragile ecotone, which sensitively responses to global change. So, the basin is an ideal site for researching global change in China. Commonly, magnetic susceptibility would well reflect environment change and has been widely applied to research Quaternary environment and climate change. A profile (DT Profile) in Datong Basin was ideally selected to study the climate change in North China. The magnetic susceptibility in the profile all indicated that the climate in North China has been very unstable since the middle Pleistocene, with frequent climate changes in different time periods. The climates in the Ice Age or in the Interglacial Period were unstable. The climate indexes in the DT Profile showed that there were several climatic fluctuations in each phase. These climate changes were well accordant with the global climate change reflected by the deep-sea oxygen isotope records and the records in polar ice cores, as well as that recorded in desert and loess depositions and evidences from the Salawusu River basin and Daihai Lake, showing a consistency in time of climate change between the study area and outside. The main factors that control the climate of the study area is East Asian monsoon.
Asphalt pavement is one of the main road surfaces in cold regions, which has heat absorption, inducing diseases to road. Solar radiation and terrestrial radiation energy fluxes on the asphalt pavement and original surface were observed in the Beiluhe section on the Tibetan Plateau. At the same time, energy radiation differences between them are compared. The results showed that: albedo of original surface is 2 to 3 times more than that of asphalt pavement. Radiant fluxes of asphalt pavement and original surface show that: in summer >in autumn >in spring >in winter, overall. The long- and short-wave radiations reaching the asphalt pavement are greater than those reaching the original surface. Upward long-wave radiation flux of asphalt pavement is greater than that of original surface. Overall, the net radiation flux of asphalt pavement were 302.2 MJ·m-2 more than that of original surface from September 2009 to August 2010. From September 2010 to August 2011, upward short-wave radiation increased relatively. As a result, the net radiation of asphalt pavement was 28.21 MJ·m-2 more than that of original surface only. Reduction of short-wave radiation and increase in long-wave radiation absorption are the significant reason for the increase of net radiation. At 5-cm depth, temperature under asphalt pavement is greater than that under original surface about 1.15-8.6 ℃. The difference in the energy radiation is a distinct factor for asphalt pavement absorbing heat.
The thermodynamic model was analysed and the similarity ratio of the model test was derived in this study. Through simulating the field-cooling process, a model test on static ice pressure was conducted in a low-temperature laboratory to examine the feasibility of simulating the developing process of static ice pressure in a laboratory. The following conclusions were drawn: the maximum ice thickness was 39.8 cm during the test, which lasted 387.4 h, with the simulated ice-freezing process corresponded with the order of natural process; At present, it is too difficult to simulate the nature solar radiation during the thawing process in the laboratory. Thus, the temperature control process should be improved; The simulated maximum static ice pressure occurs in the temperature rise period, which is related to the temperature rising rate. The temperature rising rate faster, the static ice pressure. Morover, static ice pressure reaches the maximum when the air temperature reaches 0 ℃, and then decreases quickly, which is consistent with the observation in the ice development process on reservoir.
In order to improve the fatigue performance of asphalt pavement in saline soil areas, the freezing-thawing split fatigue tests of SBS asphalt concrete immersed in water or saturated chlorine solution were carried out. The attenuation laws of freezing-thawing fatigue life of asphalt concrete were studied under the combined action of temperature and chlorine salt corrosion. The results indicate that temperature and chlorine salt corrosion are important factors which affect the freezing-thawing fatigue life of asphalt concrete. When the freezing-thawing cycles are the same, the freezing-thawing fatigue life of asphalt concrete will decrease with freezing-thawing temperature decreasing. When freezing-thawing temperature is the same, the freezing-thawing fatigue life of asphalt concrete will decrease with the freezing-thawing cycles. The freezing-thawing fatigue life of asphalt concrete in saturated chlorine salt solution is obviously lower than that in water, which shows that chlorine salt can accelerate the fatigue failure of asphalt concrete; the lower the freezing-thawing temperature is, the more serious frost damage is. Regression analysis of the test data found that there is a good exponential relation between freezing-thawing fatigue life and freezing-thawing cycles in asphalt concrete, which can be used to predict the freezing-thawing fatigue life of asphalt concrete.
A test program was conducted on the remolded frozen saline sandy soil of a roadbed construction project in Lanzhou to investigate the variation of uniaxial compressive strength with different salinities, test temperatures and strain rates. In this paper, the physical and mechanical properties of the frozen saline sandy soil and the relationships among the elastic modulus, test temperatures and salinities are investigated. The experiment results showed that the increase of the content of soluble salt will lead to gradually reduce the uniaxial compressive strength of frozen saline sandy soil, but the uniaxial compressive strength of frozen saline sandy soil will increase with the decrease of the test temperature correspondingly. The time to reaches the peak compressive strength will shorten and the uniaxial compressive strength of frozen saline sandy soil will increase, when the strain rate increase and the elastic modulus decrease owing to the increase in salinity and test temperature.
The weak interface of two holes locates on the interface of two frozen holes, but the irregularity of distribution around the design location in deep frozen shaft leads to the complexity in selection of the weak interface. For the weak interface in deep frozen shaft temperature field, with the help of the finite element method, the temperature field of the deepest frozen shaft in the world has been studied based on the actual holes in three depth levels, and the frozen wall temperature parameters of the weak interface were analyzed. It is pointed out that not only the maximum distance between holes, but also the length of the projection in designed perimeter, the inner deviation of the holes and the distribution of the adjacent holes are necessary to consider when selecting a weak interface. It is of great significance that in this paper, the length of the projection in designed perimeter is firstly pointed out as one of the factors that influence weak interface.
For high-speed railway construction in seasonally frozen soil regions, a critical technical problem is subgrade frost heaving. The frost heaving mechanisms and characteristics of subgrade padding have been researched a lot at home and abroad, but the problem of permeability of the subgrade padding has seldom been involved. In this paper, the influence of fine particle content on the subgrade padding water content and frost heaving radio were studied through laboratory experiment, and the permeability of subgrade padding was also studied, then the water diversion features and anti-frost performance of frost protection padding layer were verified by monitoring the subgrade frost heaving in the Harbin-Qiqihar High-Speed Railway. The results show that the antifreeze technical route with padding is feasible by controlling design parameters rationally, such as controlling padding component, gradation and fine particle content. Under the condition of controlling the quality of construction strictly, subgrade padding material can meet the frost protection requirements of high-speed railway subgrade.
In 2012 a serious drought happened in China. In this paper, combined with the latest state surface soil and hydrological parameters, using the soil volumetric water content products of CMA Land Data Assimilation System (CLDAS-V1.0), published in November of 2013, relative soil moisture in China in 2012 was calculated. Then, agricultural drought can be monitored based on the state standard of Agricultural Climate Center of China. The result shows that it can reflect the change of drought in all years, especially in Southwest Chia, South China, Northeast China and the Huanghuai and Jianghuai plains. It is believe that a temporal-spatial continuous real-time product can be made out to monitor the drought and to support agriculture development in China.
In this paper, based on the up-to-date OTC carbon flux measurement instrument, a new instrument is developed, which takes AT89C51 single-chip as core of control, L293D to control positive and negative turn of motor to control timing switch of box cover, and DS1232 chipset watchdog circuit as reset circuit to avoid system halt of the single-chip. The main box is made by glass fiber material with superior transparency. The motor is driven by gear. Box mouth and cover are wrapped by rubber seal to avoid gas leakage in seal. OTC inner automatic carbon flux measurement instrument can solve problems such as high observation cost, discontinuous data, impact from natural and artificial factors and irregularity in carbon flux observation under current simulated warming. An automatic, continuous and accurate carbon flux observer in permafrost regions was realized. The test shows that under the favorable weather conditions on June 15th 2013, the observer had similar observation accuracy with the traditional one, in which LI-COR6400 is made use of. They both had less error and significant correlation (R2=0.96), while under bad weather condition on September 1st 2013, OTC inner automatic carbon flux measurement instrument had better observation accuracy as compared with the traditional one. The latter had more irregular data, more error and less reliability and had poor correlation (R2=0.67). The tradition ones are recommended to be discarded.
Temporal and spatial distribution and characteristics of surface water and groundwater have greatly changed under the impacts of climate change and human activities in the middle reaches of the Heihe River. Study the evolution of water system and the mechanisms driving the change are critical for sustainable water management of the river basins. Based on groundwater levels of the monitoring wells and hydrogeological data, meteorological data, remote-sensing data and statistical irrigation data, variation of groundwater level caused by surface water allocation was studied in the middle reaches of the Heihe River in the past 30 years. Results show that the unbalanced allocation of surface water and cropland expansion have resulted in the over-abstraction of groundwater and then lowered the groundwater table and renewable quantity. Groundwater level had declined in 1985-2004, and had declined and risen again during 2005-2013. The lowering groundwater level had reached a maximum of 17.41 m in the upper and middle alluvial-diluvial fans, with a maximum rising (3.3 m) along the main Heihe River, during 1985-2013. Generally, groundwater table had risen 1.0-3.0 m. Groundwater system had fallen in severe negative balance, although the groundwater level had presented a rising tendency during 2005-2013 in Zhangye basin. It is urgent to make a rational policy of “eco-water diversion” and integration planning and management of surface water and groundwater resources in the river basin.
The Liaohe River is located in the middle and upper reaches and supplies the Khorchin sandy land. It is significant to study the runoff variation and its causes for water resources reasonable exploitation and eco-environment manage in the river basin. The climate change is attributed to hydro-thermal conditions change. The comparison way of cumulative slope change rate is improved, and runoff change, climate change and the contribution of human activities to runoff change are analyzed quantitatively based on the data from three typical hydrometric stations (Xiawa, Fushandi and Wudan) on the middle and upper reaches of the river. It is found that runoff has been decreased slowly for many years, including some increase due to precipitation increasing and some decrease due to air temperature rising. In the 2000s, runoff reached a minimum, 45.89%~82.13% of that in the 1990s. 1995 and 1998 were the runoff abrupt change years. From 1995 to 2010 (1999 to 2010) the climate change in the areas controlled by Xiawa, Fushandi and Wudan hydrometric stations contributed 41.57%、60.20% and 36.76%, respectively, to the runoff decrease, and the human activities contributed 58.43%、39.80% and 63.24%, respectively, to the runoff decrease, as compared with that from 1957 to 1994 (1957 to 1998).
The Cherchen River is a unique tributary of the Tarim River. The river directly supplies to the common terminal lake, an endorheic lake, not to the main stream of the Tarim River. The Tetima Endorheic Lake is the most important lake in southeastern Tarim Basin, but it had dried up from 1972 to 2002. Fortunately, in 2000, an Emergency Ecological Water Transfusion (EEWT) project initiated in the lower reaches of the Tarim River by Xinjiang Tarim River Basin Management Bureau. As one of many good results, Tetima Lake has refilled since 2002. In recent years, there is several research projects carried out in the lower reaches of the Tarim River to assess the effect of EEWT in different fields, such as lake area, water quality, ground water table, vegetation vitality, seed bank, biodiversity, micro climate, etc. Some research showed that water area in Tetima-Kanglayka lake region is increasing, and the main driving force of this change (EEWT project) is summarized. In this research using vegetation index and water index as determining parameters of decision tree, the land cover information, include various forms of water areas in the entire watershed of the Cherchen River sub-basin, was extracted by using Landsat Images in 1990, 2000 and 2010. Land cover changes were analyzed based on the classification system established based on 3rd level of FAO/UNEP Land Cover Classification System. It is revealed that water area changing speed in the period of 2000-2010 was faster than that in the period of 1990-2000, especially in lakes, of which area and number were increasing comparatively. Among various water bodies, glaciers and snow covers shrunk significantly. The area of glaciers and snow covers, distributed in the areas lower than 5 000 m, were account for 38.8% of all glaciers and snow covers in the entire watershed in 1990, but in 2010, it reduced to 5.4%. The area and number of rivers had changed not so much, but the area and number of lakes had increased greatly. The lakes area in 2010 was 5 times more than that in 1990, and most of new-formed lakes were distributed in the plain areas in the lower reaches. As a result of climate change and water body change, natural vegetated lands are expanding continuously both in the mountain areas and plain lands, especially those at high altitude, except for deserts (including all kinds of non-vegetated, non-water covered lands and also non-artificial lands), which are decreasing. The vegetated lands in the mountain areas are expanding faster than those in plain; accordingly, the shrinking speed of deserts in the mountains faster than that in the plain areas. Through correlation analysis, it is found that the influence of natural factors is greater than that of human factors in the whole Cherchen River watershed in the period from 1990 to 2010.
Determination of drainage area threshold plays an important role in extracting drainage network based on DEM and affects the topological and geometric characteristics of the digital river system. To investigate the drainage area threshold of the catchments in alpine regions, eight watersheds in the upper reaches of Heihe River are selected as the case study areas, watershed delineator of the soil and water assessment tool is used to extract drainage network based on DEM. Two methods for identifying drainage area threshold are discussed and compared, including the relation between drainage area threshold and the total length of drainage network method and fitness index method. The optional drainage area thresholds obtained from these two methods greatly differ each other, and the drainage network extracted under the thresholds cannot describe the real pattern of watersheds, because these two methods mainly controlled by area, topography and geometrical characteristic of the basin, and do not take account of precipitation, underlying surface condition and so on. By contrast, the fitness index method is better, as the optional drainage area threshold is identified by using actual drainage network in this method. To obtain high precision digital drainage network and improve the spatial discretization of the distributed hydrological model, the individual factors should be taken into comprehensive consideration and the watershed should be divided into sub-regions, then different drainage area thresholds are set in the sub-regions, respectively.
To understand the plant community characteristics in the periglacial areas of the Mt. Laotudingzi, eastern Liaoning mountainous regions, based on the community survey in 48 sampling areas (including 39 arbor quadrats, 192 bush quadrats and 240 herbal quadrats), using the TWINSPAN classification method, plant communities in the areas are divided into rock block field, rock glacier side and rock stream and the community structures, species constitution and life form spectra are studied systematically. The results show: 1) Plants in the areas can be divided into 16 forest formations, 6 bushy formations, merging as broadleaved deciduous forest, theropencedrymion, dark coniferous forest, elfin forest, bushwood, meadow thicket. Among them, rock block field is mainly conducive to develop bushwood and meadow thicket, with scattering theropencedrymion and elfin forest; rock stream is mainly conducive to develop theropencedrymion and broadleaved deciduous forest, with scattering dark coniferous forest; rock glacier side is mainly conducive to develop theropencedrymion, broadleaved deciduous forest and bushwood grow, with scattering elfin forest. 2) There are vascular plant species of 68 families, 138 genuses and 193 seeds in the areas, including pteridophytes of 8 families, 10 genuses and 14 seeds, gymnosperm of 1 families, 3 genuses and 4 seeds, dicotyledon of 53 families, 106 genuses and 150 seeds, monocotyledons of 6 families, 19 genuses and 25 seeds. The similarity index of the species composition of plant communities between rock block field and rock stream is 0.29-0.45, belonging to middle dissimilarity, while that between rock block field and the slope in rock stream is 0.51-0.56, belonging to middle similarity. However, except the similarity index of the species composition of the community shrub layer being 0.59, belonging to the middle similarity, the similarity index of the tree layer, herb layer and the species composition of all the community is between 0.41 and 0.49, belonging to middle dissimilarity. 3) The plant communities in the areas are Phanerophyte, accounting for 38.0%, Cryptophyte, accounting for 36.3%, and Hemicryptophyte, accounting for 21.8%. There are few Chamaephyte and Therophyte. All of these reflect that the climatic features in the areas is that the climate is warm and rainy in summer, but is cold in the long winter. Comparatively, the Cryptophytes in rock-block field and rock slope are more, accounting for 37.4% and 39.5%, respectively. The Phanerophyte in stone river areas is a little more, accounting for 46.2%. These show that the microclimate in rock-block field and rock slope is more cold and wet.
In this study, it is aimed to characterize the physiological and phylogenetic diversity of bacteria isolated from the meltwater of the Glacier No.1 at headwater of the Ürümqi River in Tianshan Mountains, China. Using culture medium of R2A, 10% and full strength tryptic soy agar, a total of 36 aerobic bacteria strains were isolated from the meltwater of the Glacier No.1. Phenotypic characteristics of the isolated strains were examined, including the tolerance to NaCl, temperature range for growth, enzyme activity and antibiotic resistance. 16S rRNA gene sequence analysis and microscopy indicated that the isolated strains were dominated by Gram-negative bacteria. Based on 16S rRNA gene sequences, it is found that the isolates are members of α, β and γ of Proteobacteria, Actinobacteria and Bacteroides group. The most abundant and diverse isolates are within the Bacteroidetes (41.7%) and γ-Proteobacteria (38.9%). More than one-third of the isolates could be tentatively identified as Pseudomonas spp. According to the temperature range for growth, it is believed that most of the isolates (80%) are psychrotrophic ones. Among 36 isolates, seven are resistant to all antibiotics. In addition, thirty-three isolates have potentially useful cold-active enzymes, including those with proteolytic, amylolytic, lipolytic, and cellulose-hydrolyzing activities. The results will enrich the knowledge of the phylogenetic and physiological diversity of cold-adapted strains in cold environments.
Soil samples were collected under shrub of Tamarix in Marine Ecology Special Reserve, a national reserve in Changyi city of Shandong Province, to determine the microbial biomass. Results showed that ribosomal gene copies of bacteria, fungi, and archaea are 8.24×106 copies·g-1, 1.51×104 copies·g-1, 2.85×104 copies·g-1, respectively. The mean microbial biomass carbon and nitrogen are 140.54 mg·kg-1 and 29.19 mg·kg-1, respectively. From the dense zone, the sparse zone to the marginal zone, microbial biomass decreases with vegetation coverage. Correlation analysis indicates that the differences in organic matter input caused by vegetation coverage are the main factors for variance of microbial biomass. The establishment and growth of Tamarix provided stable growth conditions for soil microorganisms in the shallow layer of soil, resulting in similar microbial biomass under shrub of Tamarix from different habitats. Yet, there are large differences in microbial activity, e.g., a significant high microbial biomass carbon and nitrogen in costal saline-alkali soil than that in desert ecosystem.
A bacteria strain (BGQ-6) was isolated from the soil sample in the Bangeqiao area of the Tibetan Plateau. The BGQ-6 can grow well within the medium with crude oil as carbon source. The 16S rRNA gene sequence and Biolog GEN III analysis showed that this strain has a high similarity with Rhodococcus qingshengii, and it is identified as Rhodococcus qingshengii BGQ-6. The strain at the logarithmic growth phase was incubated to the MM medium and cultured at 10 ℃ and 150 rpm for 15 d, and the results of gas chromatograph (GC) detection showed that BGQ-6 strain can degraded by 74.14% of crude oil added in the medium. Further analysis indicates that BGQ-6 is able to degrade 60 kinds of hydrocarbon with a high degradation rate, including alkanes, alkane, cyclones, and aromatic hydrocarbon. Using the method of degenerate PCR, we identified two kinds of oil degrading genes, alkB and almA, which encode hydroxylases, and alkB has 4 members and almA has 1 copy in the genome of BGQ-6.
In this paper, the effect of NaCl solution stress with different concentrations on the ecophysiological characteristics of transplanted seedlings of Stevia rebaudiana Bertoni with pot method was researched. The result showed that the NaCl solution with low concentration may promote the transplanted seedlings of stevia growing and that the NaCl solution with high concentration may suppress reversely. When the concentration is 0-44 mmol·L-1, the NaCl solution would promote the photosynthesis and growth of transplanted seedlings of stevia; when the concentration is 44-140 mmol·L-1, the photosynthetic parameters, dry leaf yield and growth would decrease by degrees; when concentration is greater than 140 mmol·L-1 the stevia cannot survive. Under the stress of NaCl solution with low concentration, the leaf yield of stevia increases. However, the growing of stems and roots would be suppressed. It was a new mechanism for increasing stevia leaf yield that stevia adapt to low salt stress by increasing leaf biomass. It is revealed that new evidence for the study of allocation of biomass. Moreover, the identified Na+ solution range, lower than which the growth of stevia would be promoted and higher than which the growth of stevia would be inhibited, will provide theoretical basis for planting stevia in large-scale and finely.
Livelihood capital of residents in the Chengdu area is severely affected by farmland utilization ratio and multi-livelihood capitals. However, livelihood capital plays a crucial role in promoting rural economic development and raising farmer's intention of protecting cultivated land. In this paper, it is tried to disclose the latent relations between farmers' livelihood capital and their intention of cultivated land protection with Structure Equation Model (SEM) method. The results indicate that livelihood capital has remarkable influence on the intention of protecting cultivated land of farmers. Specifically, the natural capital and social capital have a positive impact on the intention, which will be increasing linearly by 0.071 units and 0.011 units, respectively, for one unit increase in natural capital and social capital. While, the physical capital, financial capital and human capital have a negative impact, e.g., a unit increase in physical capital, financial capital and human capital will decrease the farmers' intention of protecting cultivated land by 1.231 units, 1.030 units and 0.232 units, respectively. Indeed, the farmers' intention of cultivated land protection is affected by many invisible factors. However, livelihoods capital is one of the most important factors that determine the farmers' willingness for farmland protection. In order to improve the achievement of cultivated land protection policy, the government should further understand farmers' requirements with different livelihoods capitals. An insightful analysis of the internal links will help government to develop sustaining and efficient policy of cultivated land protection and to increase farmer's intention of protecting cultivated land.
