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1.
XIANG Longwei WANG Hansheng JIANG Liming SHEN Qiang Holger STEFFEN LI Zhen 《干旱区科学》2021,13(3):224-238
We provide estimates of glacier mass changes in the High Mountain Asia (HMA) area from April2002 to August 2016 by employing a new version of gravity solutions of the Gravity Recovery and ClimateExperiment (GRACE) twin-satellite mission. We find a total mass loss trend of the HMA glaciers at a rateof –22.17 (±1.96) Gt/a. The largest mass loss rates of –7.02 (±0.94) and –6.73 (±0.78) Gt/a are found forthe glaciers in Nyainqentanglha Mountains and Eastern Himalayas, respectively. Although most glaciers inthe HMA area show a mass loss, we find a small glacier mass gain of 1.19 (±0.55) and 0.77 (±0.37) Gt/a inKarakoram Mountains and Western Kunlun Mountains, respectively. There is also a nearly zero massbalance in Pamirs. Our estimates of glacier mass change trends confirm previous results from the analysisof altimetry data of the ICESat (ICE, Cloud and Land Elevation Satellite) and ASTER (AdvancedSpaceborne Thermal Emission and Reflection Radiometer) DEM (Digital Elevation Model) satellites inmost of the selected glacier areas. However, they largely differ to previous GRACE-based studies which weattribute to our different post-processing techniques of the newer GRACE data. In addition, we explicitlyshow regional mass change features for both the interannual glacier mass changes and the 14-a averagedseasonal glacier mass changes. These changes can be explained in parts by total net precipitation (netsnowfall and net rainfall) and net snowfall, but mostly by total net radiation energy when compared to datafrom the ERA5-Land meteorological reanalysis. Moreover, nearly all the non-trend interannual masschanges and most seasonal mass changes can be explained by the total net radiation energy data. The massloss trends could be partly related to a heat effect due to increased net rainfall in Tianshan Mountains, QilianMountains, Nyainqentanglha Mountains and Eastern Himalayas. Our new results for the glacier mass changein this study could help improve the understanding of glacier variation in the HMA area and contribute tothe study of global change. They could also serve the utilization of water resources there and in neighboringareas. 相似文献
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以新疆地产赤霞珠葡萄籽为原料,采用响应面法对微波辅助提取葡萄籽原花青素的工艺进行优化,并对其体外抗氧化活性进行评价。结果表明,最优提取工艺条件为:液料比25∶1(mL/g),乙醇浓度60%,微波功率427 W,微波时间3 min,在该条件下葡萄籽原花青素得率为8.66%±0.25%;抗氧化试验结果表明:葡萄籽原花青素具有较强的清除1,1-二苯基-2-三硝基苯肼(DPPH)、羟基及2,2-联氮-双(3-乙基-苯并噻唑-6-磺酸)二铵盐(ABTS)自由基的能力,其在三种体系中的IC50值分别为3.71、4.05和3.78 μg/mL,是一种极具开发潜力的天然抗氧化剂。 相似文献
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不同氮素水平下双季稻株型与冠层内光截获特征研究 总被引:1,自引:0,他引:1
本文旨在阐明双季稻株型与冠层内光合有效辐射截获的时空分布特征。选用4个不同株型早、晚稻品种,设置4个不同施氮水平,系统观测其植株形态和冠层内光合有效辐射截获率(IPAR)的时空分布状况。结果表明,施氮水平对早、晚稻株高、穗长、叶长和叶基角均有显著影响,均表现为随施氮水平的增加而增大;早、晚稻孕穗期的分层叶面积指数(LAI)和向上累积LAI大于抽穗后12 d,分层LAI呈冠层中部大于上部和下部的分布特征,最大分层LAI出现在0.58相对高度处;冠层上中部分层LAI和向上累积LAI随施氮水平的增加而增大;向上累积LAI随相对高度呈S型曲线分布,可用Logistic方程定量描述(R~2 0.99);早、晚稻孕穗期的冠层IPAR大于抽穗后12 d,且随施氮水平的增加而增大,其日变化表现为正午较小,早晚较大;株型紧凑的早、晚稻品种,冠层IPAR低;冠层IPAR与向下累积LAI之间的关系可用方程IPAR=a (1-e~(-b×LAI))定量描述(R~2 0.88);冠层内IPAR的三维空间分布表现为冠层上中部水平面上IPAR较低,光斑变化大,冠层下部水平面上IPAR较高,光斑变化较平缓,同一冠层高度水平面上的IPAR呈不均匀分布。研究结果可为双季稻高产栽培及理想株型的优化设计提供支撑。 相似文献
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以竹代塑新产品竹微丝复合包装材料的制备及其性能 总被引:1,自引:1,他引:0
为减少塑料制品的使用,缓解其对全球环境的污染,以质量分数为90%的竹微丝、2%的聚乙烯、8%的甘油制备竹微丝复合材料,参照传统竹编织技艺,分别采用纯纵向编织法和纵横向编织法等制备了竹微丝复合包装材料,并对其性能进行分析。结果表明:1)与通过传统竹篾工匠手工制备的竹微丝相比,由大型智能化竹拉丝设备制备的竹微丝边缘更整齐;2)与竹微丝单方向编织技术相比,采用纵横向交叉编织技术的竹微丝复合包装材料的抗拉性能更好;3)竹微丝复合包装材料的拉伸强度远大于PE、PVC等传统塑料包装材料。 相似文献
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The transformation of natural landscapes into impervious built-up surfaces through urbanization is known to significantly interfere with the ecological integrity of urban landscapes and accelerate climate change and associated impacts. Although urban reforestation is widely recognised as an ideal mitigation practice against these impacts, it often has to compete with other lucrative land uses within an urban area. The often limited urban space provided for reforestation therefore necessitates the optimization of the ecological benefits, which demands spatially explicit information. The recent proliferation of tree stands structural complexity (SSC) and topographic data offer great potential for determining the ecological performance of reforested areas across an urban landscape. This study explores the potential of using topographic datasets to predict SSC in a reforested urban landscape and ranks the value of these topographic variables in determining SSC. Tree structural data from a reforested urban area was collected and fed into a tree stand structural complexity index, which was used to indicate ecological performance. Topographic variables (Topographic Wetness Index, slope, Area Solar Radiation and elevation)- were derived from a Digital Elevation Model (DEM) and used to predict SSC using the Partial Least Squares (PLS) regression technique. Results show that SSC varied significantly between the topographic variables. Results also show that the topographic variables could be used to reliably predict SSC. As expected, the Topographic Wetness Index and slope were the most important topographic determinants of SSC while elevation was the least valuable. These results provide valuable spatially explicit information about the ecological performance of the reforested areas within an urban landscape. Specifically, the study demonstrates the value of topographic data as aids to urban reforestation planning. 相似文献
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Impact of sampling and storage technique,and duration of storage,on the composition of fresh grass when analysed using near‐infrared reflectance spectroscopy 下载免费PDF全文
The objective of this study was to examine the effect of sampling technique (pluck or cut), storage duration (immediate analysis, 24‐h or 48‐h), storage temperature (ambient or chilled) and storage conditions (air present, air excluded or breathable) on the composition of fresh grass sampled from a sward managed to simulate grazing. Treatments were repeated across four sampling dates, with grass samples stored in grip seal bags prior to analysis using near‐infrared reflectance spectroscopy. Grass sampled by ‘pluck’ had a higher crude protein and ME content, and a lower acid detergent fibre (ADF) content, compared to that sampled by ‘cut’. Grass stored for 48 h had a lower water soluble carbohydrate (WSC) and ME content and a higher ADF content than for immediate analysis. Samples stored for 24 h did not differ from immediate analysis. Grass stored at ambient temperature had a lower WSC and ME content compared to immediate analysis. Grass stored under ‘breathable’ conditions had a lower ME content and higher ADF content than immediate analysis or samples stored with air present or air excluded. It is recommended that grass for analysis should be sampled by cutting, stored chilled (4°C) in a sealed bag to minimize exposure to oxygen and analysed within 24 h of harvest. 相似文献