Studies on the reflectance spectral features of saline soil along the middle reaches of Tarim River: a case study in Xinjiang Autonomous Region, China

There has been growing interest in the use of reflectance spectroscopy as a rapid and inexpensive tool for soil characterization. In this study, 53 soil samples were collected from the oasis in the Weigan and Kuqa River delta along the middle reaches of Tarim River to investigate the level of soil chemical components in relation to soil spectral. An approach combining spectral technology and multi-variant statistical analysis was used to determine the reflectance spectral features of saline soil. The spectral data was first pretreated to remove noises and absorption bands from water, which eliminated influence from instrument errors and other external background factors. Several spectral absorption features were calculated for several saline soil samples to confirm that soil at the same salinity level had similar absorption spectral properties. Secondly, a correlation relationship between reflectance spectra and salinity factors was estimated by bivariate correlation method. Fourteen salinity factors including eight major ions and soil electrical conductivity (EC), soil salt content (SSC), pH, and total dissolved solid (TDS) in the saline soil were evaluated. Datasets of the salinity factors that correlated significantly with field data measurements of reflectance rate and the corresponding spectrum data were used to construct quantitative regression models. According to the multiple linear regression analysis, SSC, SO₄ ^2?, TDS, and EC had a correlation coefficient at 0.746, 0.908, 0.798, and 0.933 with the raw spectral data, respectively, which confirmed strong correlation between salinity factors and soil reflectance spectrum. Findings from this study will have significant impact on characterization of spectral features of saline soil in oasis in arid land.     

主题村落再造:非物质文化遗产旅游开发模式研究

非物质文化遗产是重要的文化旅游资源,村落是非物质文化遗产的主要载体,适宜的旅游开发模式有助于非物质文化遗产的保护与传承,有利于文化旅游业的可持续发展。以三峡步步升文化村为案例,在分析所依托资源特点、开发现状及旅游开发策略的基础上,归纳提炼得出传统手工技艺类非物质文化遗产旅游开发的"主题村落再造"模式,即以主题村落为载体,以文化旅游为功能,以活态传承为方式,以聚集开发为手段,整体形成一个极富活力的生态文化博物村落。     

Southwest China and Southeast Asia: towards sustainability through cooperative development and management of international rivers *

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Nitrogen isotope fractionations in the Fischer-Tropsch synthesis and in the Miller-Urey reaction

Nitrogen isotope fractionations have been measured in Fischer-Tropsch and Miller-Urey reactions in order to determine whether these processes can account for the large¹⁵N/¹⁴N ratios found in organic matter in carbonaceous chondrites. Polymeric material formed in the Fischer-Tropsch reaction was enriched in¹⁵N by only 3‰ relative to the starting material (NH₃). The¹⁵N enrichment in polymers from the Miller-Urey reaction was 10–12‰. Both of these fractionations are small compared to the 80–90‰ differences observed between enstatite chondrites and carbonaceous chondrites. These large differences are apparently due to temporal or spatial variations in the isotopic composition of nitrogen in the solar nebula, rather than to fractionation during the production of organic compounds.     

A fluid experiment of large-scale topography effect on baroclinic wave flows

The effects of topography on baroclinic wave flows are studied experimentally in a thermally driven rotating annulus of fluid.Fourier analysis and complex principal component (CPC) analysis of the experimental data show that, due to topographic forcing, the flow is bimodal rather than a single mode. Under suitable imposed experimental parameters, near thermal Rossby number ROT = 0.1 and Taylor number Ta = 2.2 × 107, the large-scale topography produces low-frequency oscillation in the flow and rather long-lived flow pattern resembling blocking in the atmospheric cir-culation. The ‘blocking’ phenomenon is caused by the resonance of travelling waves and the quasi-stationary waves forced by topography.The large-scale topography transforms wavenumber-homogeneous flows into wavenumber-dispersed flows, and the dispersed flows possess lower wavenumbers.     

大气二氧化碳对CO2激光辐射各谱线的吸收

本文给出了大气二氧化碳对CO_2激光辐射各谱线吸收的计算公式,并利用标准大气资料计算了各谱线的吸收值。发现在P支谱线中,P(16)线吸收最大;在R支谱线中,R(16)线为最大。当转动量子数J大于或小于16时,吸收值随J值的增大或减小几乎成指数减小。为了验证计算公式的可靠性,在实验室中进行了模拟大气测量,其测量结果和理论计算结果具有较好的一致性。     

Dynamics of land surface temperature (LST) in response to land use and land cover (LULC) changes in the Weigan and Kuqa river oasis,Xinjiang, China

Land use and land cover (LULC) changes caused by human activities have strong influences on regional environment. Land surface temperate plays an important role in studying the impact of LULC changes on regional environment. In this paper, remotely sensed thermal infrared data were used to assess land surface temperature (LST) in the Weigan and Kuqa river oasis, Xingjiang, one of the important agricultural areas in the northwestern China. The present study deals with the extraction of LST and the relationship between LULC changes using Landsat 5 TM acquired on September 25, 1989, and September 6, 2011. The results indicate that the surface temperature of water body, bare land, and desert changed significantly between 1989 and 2011. In general, the LST was lower in 1989 than in 2011. There were no lower, higher, and highest temperature zones in 1989. However, the minimum temperature was 10.7 °C in 1989 and 15.8 °C in 2011. The maximum temperature was 29.3 °C in 1989 and 41.8 °C in 2011. Regarding the LULC types, the desert features in the Gobi Desert warmed more quickly than the oasis. So, the temperature of the oasis was lower than the surrounded areas, resulting in a so-called “cold island” phenomenon. Oasis cold island effect index (OCIEI) shows that stability of oasis had rising trend from 1989 to 2011. In addition, the impact of LULC changes on LST was analyzed and the driving forces were also analyzed from 1977 to 2011. This study is significant for further understanding of the energy exchange status of soil-plant-atmospheric system and the regional heat distribution in arid and semi-arid areas of the northwest China.     

High-temperature elasticity of magnesioferrite spinel

The elastic moduli of magnesioferrite spinel, MgFe₂O₄, and their temperature dependence have been determined for the first time by ultrasonic measurements on a polycrystalline specimen. The measurements were carried out at 300 MPa and to 700°C in a gas-medium high-pressure apparatus. On heating, both the elastic bulk (K _S) and shear (G) moduli decrease linearly to 350°C. By combining with extant thermal-expansion data, the values for the room-temperature K _S and G, and their temperature derivatives are as follows: K ₀ = 176.3(7) GPa, G ₀ = 80.1(2) GPa, (∂K _S/∂T) _P = −0.032(3) GPa K⁻¹ and (∂G/∂T) _P = −0.012(1) GPa K⁻¹. Between 350 and 400°C, there are abrupt increases of 1.4% in both of the elastic moduli; these closely coincide with the magnetic Curie transition that was observed by thermal analyses at about 360°C.     

沙冬青植物群落研究

沙冬青植物群落是中国沙漠地区特有的常绿植物群落，分布在荒漠区东部及荒漠草原地区。１９９１年在沙坡头地区北部的腾格里沙漠沙葱湾－通湖山一带发现有大片分布，面积达７１３３ｈａ。沙冬青植物群落的建群种沙冬青是第三纪古老的残遗种，我国已将它列入第一批珍贵稀濒危保护植物。不仅在科学研究上具有特殊意义，而且其耐旱性强，是沙漠及黄土地区适宜的防风固沙及水土保持林种，也可用作花卉，值得大力推广。