Response of soil aggregate disintegration to the different content of organic carbon and its fractions during splash erosion     

Hairu Li  Gang Liu  Ju Gu  Hong Chen  Hongqiang Shi  Mohamed A. M. Abd Elbasit  Feinan Hu 《水文研究》2021,35(2):e14060

Aggregate disintegration is a critical process in soil splash erosion. However, the effect of soil organic carbon (SOC) and its fractions on soil aggregates disintegration is still not clear. In this study, five soils with similar clay contents and different contents of SOC have been used. The effects of slaking and mechanical striking on splash erosion were distinguished by using deionized water and 95% ethanol as raindrops. The simulated rainfall experiments were carried out in four heights (0.5, 1.0, 1.5 and 2.0 m). The result indicated that the soil aggregate stability increased with the increases of SOC and light fraction organic carbon (LFOC). The relative slaking and the mechanical striking index increased with the decreases of SOC and LFOC. The reduction of macroaggregates in eroded soil gradually decreased with the increase of SOC and LFOC, especially in alcohol test. The amount of macroaggregates (>0.25 mm) in deionized water tests were significantly less than that in alcohol tests under the same rainfall heights. The contribution of slaking to splash erosion increased with the decrease of heavy fractions organic carbon. The contribution of mechanical striking was dominant when the rainfall kinetic energy increased to a range of threshold between 9 J m⁻² mm⁻¹ and 12 m⁻² mm⁻¹. This study could provide the scientific basis for deeply understanding the mechanism of soil aggregates disintegration and splash erosion.  相似文献   

Optimization of 3D building models by GPS measurements     

Wada  Yutaro  Hsu  Li-Ta  Gu  Yanlei  Kamijo  Shunsuke 《GPS Solutions》2017,21(1):65-78

GPS Solutions - Recently, 3D building models have become an important aid to many positioning methods such as LiDAR and GPS positioning. Creating an accurate 3D building model requires accurate 2D...  相似文献   

A novel method for detecting abrupt dynamic change based on the changing Hurst exponent of spatial images     

Wen-Ping He  Qun-Qun Liu  Bin Gu  Shan-Shan Zhao 《Climate Dynamics》2016,47(7-8):2561-2571

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Intra-interstadial environmental changes in Last Glacial loess revealed by molluscan assemblages from the Upper Palaeolithic site of Amiens-Renancourt 1 (Somme,France)     

Olivier Moine  Pierre Antoine  Sylvie Coutard  Gilles Guérin  Christine Hatté  Clément Paris  Ségolène Saulnier-Copard 《第四纪科学杂志》2021,36(8):1322-1340

The Amiens-Renancourt 1 site recently yielded one of the most important Upper Palaeolithic human occupations of northern France by the number of flint artefacts and especially by the presence of Venus figurines. All the material comes from a single archaeological layer located in a tundra gley bracketed by loess units. A multi-proxy study combining a detailed stratigraphy, luminescence and radiocarbon datings and high-resolution (5 cm per sample) grain size and molluscan analyses was therefore carried out to reconstruct and date the associated environmental changes and to determine the exact context of the human occupation. The chronological frame thus established supports the correlations of the archaeology-bearing tundra gley and of an underlying arctic brown soil with Greenland interstadials GI-4 and GI-3. Composition changes in the molluscan population enabled the identification of transitional and optimum phases and sub-phases within these two pedogenetic horizons. A conceptual correlation model linking molluscan phases with millennial-scale variations of Greenland ice-core and Sieben Hengste speleothem climate records is proposed. The Human occupation appears contemporaneous to the end of the stadial–interstadial transition of GI-3. Synchronous in Amiens-Renancourt 1 and Nussloch, subsequent micro-gleys may also result from a regional/global forcing. Such a level of detail is unprecedented in a loess sequence.  相似文献   

Zinc-rich clays in supergene non-sulfide zinc deposits     

F. Choulet  M. Buatier  L. Barbanson  R. Guégan  A. Ennaciri 《Mineralium Deposita》2016,51(4):467-490

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Climate change and human impact in a sensitive ecosystem: the Holocene environment of the Northwest Icelandic highland margin   总被引：1，自引：0，他引：1       下载免费PDF全文

Sigrún D. Eddudóttir  Egill Erlendsson  Leone Tinganelli  Guðrún Gísladóttir 《Boreas: An International Journal of Quaternary Research》2016,45(4):715-728

Complex interactions of climate and volcanic activity have shaped the environment of Iceland during the Holocene. Palaeoecological records from Iceland offer a unique look at a Holocene environment that was uninhabited by humans and free of mammal herbivores until about AD 870. We present a new reconstruction of Holocene vegetation and landscape dynamics from a small lake, Barðalækjartjörn, located near the highland margin in Northwest Iceland. A multi‐proxy approach was used to reconstruct vegetation based on pollen and plant macrofossil analysis and landscape stability based on lithological proxies. The record covers the period c. 10 300–200 cal. a BP. For the first two millennia aeolian processes probably played a part in vegetation development. This period is characterized by high input of minerogenic material into the lake and a vegetation assemblage in which plants tolerant of aeolian deposition are prominent. Betula pubescens woodland reached a maximum between c. 7400 and 6500 cal. a BP. Betula nana‐dominated dwarf shrub heath replaced woodland after c. 4000 cal. a BP, following the onset of Neoglaciation. Land use following human settlement caused an environmental shift at the highland margin. Betula pubescens probably disappeared from the vicinity of the lake soon thereafter. Large‐scale soil erosion began at c. 1000 cal. a BP in the wake of human activities, such as introduction of grazing livestock and woodcutting. This study offers an important long‐term perspective of the development of the highland ecosystem under both wholly natural and human‐influenced conditions.  相似文献   

依兰-伊通断裂新构造活动规律分析          下载免费PDF全文

翟明见  朱光  刘备  顾承串  张帅  林少泽  宋利宏 《地质科学》2016,(2):594-618

作为郯庐断裂带北段主干的依兰-伊通断裂, 其新构造活动性与活动规律仍然存在不同的认识.本次工作通过详细的野外调查, 发现该断裂内活断层广泛存在, 由东、西两支北东走向的主干活断层构成, 沿着古近纪地堑边界断层发育.这些活断层主要呈破碎型结构, 多为逆右行平移活动.通过对这些活断层一系列实测擦痕反演应力场, 显示它们多是在东西向挤压中活动的, 而现今应力场转变为北东东-南西西向区域性挤压.依据本次野外观察与¹⁴ C定年, 并结合前人定年结果与近代地震分布, 表明依兰-伊通西支活断层的最新活动时代为全新世与晚更新世相间, 而东支活断层的最新活动时代主要为早-中更新世.依兰-伊通断裂内活断层显示了明显的差异性活动, 表现为西支的活动强度明显大于东支, 西支的最新活动时代皆晚于东支, 沿走向上活动性强、弱相间与最新活动时代不断变化, 以及近代地震活动不均一分布.它们沿走向上的分段性、差异性活动主要是因为被一系列北西向断层切断所致.  相似文献   

A GCM investigation of dust aerosol impact on the regional climate of North Africa and South/East Asia     

Y. Gu  Y. Xue  F. De Sales  K. N. Liou 《Climate Dynamics》2016,46(7-8):2353-2370

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淮河流域夏季降水异常与若干气候因子的关系   总被引：5，自引：2，他引：3       下载免费PDF全文

王月  张强  顾西辉  孔冬冬 《应用气象学报》2016,27(1):67-74

基于旋转经验正交函数分解 (REOF) 方法探讨淮河流域1961—2010年夏季降水与厄尔尼诺/南方涛动 (ENSO)、北大西洋涛动 (NAO)、印度洋偶极子 (IOD)、太平洋年代际振荡 (PDO) 之间的关系,并进一步分析各气候因子不同位相单独以及联合对淮河流域夏季降水的影响。结果表明:淮河流域夏季降水与ENSO,PDO,NAO,IOD等气候因子具有较稳定的相关性,其中,PDO和IOD是影响淮河流域夏季降水的关键因子,且PDO与夏季降水呈显著负相关关系;各气候因子的冷暖位相单独及联合对淮河流域夏季降水的影响不同,PDO的冷期以及NAO,IOD冷位相使流域北部的夏季降水量呈显著增加趋势,PDO分别联合ENSO,NAO和IOD的冷、暖位相对流域北部地区和淮河上游地区的夏季降水影响显著。  相似文献   

FY-3微波成像仪10.6 GHz通道超分辨率图像重建          下载免费PDF全文

陈博洋  谷松岩  陈凡胜 《应用气象学报》2016,27(1):123-128

为改善风云三号 (FY-3) 微波成像仪10.6 GHz通道空间分辨率,提出利用超分辨率图像重建算法进行图像重建。分析并指出FY-3微波成像仪10.6 GHz通道具有过采样特征,具备重建得到高于瞬时视场图像的潜力;基于超分辨率图像重建理论,根据FY-3气象卫星轨道、姿态,微波成像仪性能参数以及工作模式等物理约束,建立微波成像仪的超分辨率成像模型,并推导计算出超分辨率成像模型参数;采用POCS算法重建得到10.6 GHz通道的超分辨率图像,采用目视比较分析、图像统计分析对重建图像进行质量评价:重建图像像元平均梯度提高26.5%,功率谱分量和提高5.7%,重建图像具有更高的空间分辨率;台风亮温分析应用显示了从重建图像可发现更微小的景物细节目标。采用超分辨率图像重建算法对FY-3微波成像仪10.6 GHz通道进行重建处理,结果有效且正确,可为数据用户提供更多可用的遥感数据,对微波遥感数据应用具有提升作用。  相似文献