分类: 地球科学 >> 地质学 提交时间: 2017-11-24 合作期刊: 《古脊椎动物学报》
摘要: Reconstructing the diet of extinct species is a fundamental goal in vertebrate paleobiology. Dental calculus is the calcium phosphate deposits on teeth, which captures a large number of food particles and contains the food information of ancient animal. It is possible to explore ancient animal dietary and investigate the environmental information from dental calculus. A large number of starch granules were found in dental calculus of Dicros gansuensis excavated from the earliest Late Miocene Guonigou fauna of the Linxia Basin, Gansu Province. It is the first time that starch granules from Late Miocene were found. We classified the ancient starch granules by its morphological characteristics and also analyzed the starch granules of leaves of modern plants around the living environment of D. gansuensis to find modern starch granules and compare them with ancient ones. The results indicate that D. gansuensis may eat not only shrubs leaves, such as the plant from Caprifoliaceae, but also some tree leaves from Juglandaceae (walnut), and maybe some herbs from Ranunculaceae and Polygonaceae. It is consistent with the results of previous morphological studies, and it also provides more information. Our study extends the range of time and object for dental calculus research, and offers more possibilities for research on feeding habits of ancient mammals.
分类: 地球科学 >> 地理学 提交时间: 2017-11-07 合作期刊: 《干旱区科学》
摘要: Based on daily precipitation data from 163 meteorological stations, this study investigated precipitation changes in the mid-latitudes of the Chinese mainland (MCM) during 1960–2014 using the climatic trend coefficient, least-squared regression analysis, and a non-parametric Mann-Kendall test. According to the effects of the East Asian summer monsoon on the MCM and the climatic trend coefficient of annual precipitation during 1960–2014, we divided the MCM into the western MCM and eastern MCM.
分类: 地球科学 >> 地理学 提交时间: 2017-11-07 合作期刊: 《干旱区科学》
摘要: Precipitation chemistry analysis is essential to evaluate the atmospheric environmental quality and identify the sources of atmospheric pollutants. In this study, we collected a total of 480 precipitation samples at 6 sampling sites in the northern and southern slopes of Wushaoling Mountain from May 2013 to July 2014 to analyze the chemical characteristics of precipitation and to identify the main sources of ions in precipitation.
分类: 地球科学 >> 地理学 提交时间: 2017-11-07 合作期刊: 《干旱区科学》
摘要: Arid regions are highly vulnerable and sensitive to drought. The crops cultivated in arid zones are at high risk due to the high evapotranspiration and water demands. This study analyzed the changes in seasonal and annual evapotranspiration (ET) during 1951-2016 at 50 meteorological stations located in the extremely arid, arid, and semi-arid zones of Pakistan using the Penman Monteith (PM) method.
分类: 地球科学 >> 地理学 提交时间: 2017-11-07 合作期刊: 《干旱区科学》
摘要: Urumqi Glacier No. 1 is a representative glacier in the inland areas of Central Asia and is the only Chinese reference glacier in the World Glacier Monitoring Service. In this study, we explored multi-decadal variations in the flow velocity of the glacier and the influencing factors based on continuous field observations and path coefficient analysis.
分类: 地球科学 >> 地理学 提交时间: 2017-11-07 合作期刊: 《干旱区科学》
摘要: The Lanzhou-Xinjiang High-speed Railway runs through an expansive windy area in a Gobi Desert, and sand-blocking fences were built to protect the railway from destruction by wind-blown sand.
分类: 地球科学 >> 地理学 提交时间: 2017-11-07 合作期刊: 《干旱区科学》
摘要: Soil carbon pools could become a CO2 source or sink, depending on the directions of land use/cover changes. A slight change of soil carbon will inevitably affect the atmospheric CO2 concentration and consequently the climate.
分类: 地球科学 >> 地理学 提交时间: 2017-11-07 合作期刊: 《干旱区科学》
摘要: Salt expansion in sulfate saline soils that are wider distributed in northwestern China causes serious infrastructural damages under low-temperature conditions. However, the mechanism of salt expansion under low temperatures is not clear.
分类: 地球科学 >> 地理学 提交时间: 2017-11-07 合作期刊: 《干旱区科学》
摘要: Detecting near-surface soil freeze-thaw cycles in high-altitude cold regions is important for understanding the Earth's surface system, but such studies are rare. In this study we detected the spatial-temporal variations in near-surface soil freeze-thaw cycles in the source region of the Yellow River during the period 2002-2011 based on data from the Advanced Microwave Scanning Radiometer for the Earth Observing System
分类: 地球科学 >> 地理学 提交时间: 2017-11-07 合作期刊: 《干旱区科学》
摘要: The major objective of this study was to evaluate the effects of sand mining disturbances on the diversity of arbuscular mycorrhizal fungi (AMF). In addition, the proportional changes in the diversityof AMF to the distances from riverbanks were assessed.
分类: 地球科学 >> 地理学 提交时间: 2017-11-07 合作期刊: 《干旱区科学》
摘要: Water-use efficiency(WUE) is a key plant functional trait that plays a central role in the global cycles of water and carbon. Although increasiing precipitahon may cause vegetation changes, few studies have explored the linkage between alteration in vegetation and WUE.
分类: 地球科学 >> 地理学 提交时间: 2017-11-07 合作期刊: 《干旱区科学》
摘要: Due to increasing global demand fox crop production and energy use, more and more reactive nitrogen (Nx) has been generated and emitted to the environment. 11s a result, global atmospheric nitrogen (N) deposition has tripled since the industrial revolution and the ecological environment and human health have been harmed. In this study we measured dry and wet/bulk N deposition from July 2013 to December 2015 in a semi-arid grassland of Duolun County Inner Mongolia, China. The samples of dry and wet/bulk N deposition were collected monthly with a DELT11 (DEnudex fox Long Texm 1ltmosphexic sampling system and with Gxadko passive samplers and a precipitation gauge. The measured results show that the annual mean
分类: 地球科学 >> 地理学 提交时间: 2017-11-07 合作期刊: 《干旱区科学》
摘要: Meteorological drought is a natural hazard that can occur under all climatic regimes. Monitoringthe drought is a vital and important part of predicting and analyzing drought impacts. Because no singleindex can represent all facets of meteorological drought,二took a multi-index approach for droughtmonitoring in this study. We assessed the ability of eight precipitation-based drought indices (SPI(Standardized Precipitation Index), PNI (Percent of Normal Index), DI (Deciles index), EDI (Effectivedrought index), CZI (China-Z index), MCZI (i}Modified CZI), Rr1I (Rainfall Anomaly Index), and ZSI(Z一score Index)) calculated from the station-observed precipitation data and the r}gi}MERRr} griddedprecipitation data to assess historical drought events during the period 1987-?010 for the Kashafrood Basin of Iran. We also presented the Degree of Dryness Index (DDI) for comparing the intensities of different drought categories in each year of the study period (1987-2010). In general, the correlations among drought indices calculated from the AgMERRr1 precipitation data were higher than those derived from the station-observed precipitation data. r1ll indices indicated the most severe droughts for the study period occurred in 2001 and 2008. Regardless of data input source, SPI, PNI, and DI were highly inter-correlated (B2=0.99). Furthermore, the higher correlations (B2=0.99) were also found between CZI and MCZI, and between ZSI and Rr1I. r1ll indices were able to track drought intensity but EDI and Rr1I showed higher DDI values compared with the other indices. Based on the strong correlation among drought indices derived from the AgMERRr1 precipitation data and from the station-observed precipitation data.MERRr1 precipitation data can be accepted to fill the gaps existed in the station-observed precipitation data in future studies in Iran. In addition, if tested by station-observed precipitation data, the :}gi}IERR:} precipitation data may be used for the data-lacking are as.