نتایج جستجو برای: layer soil

تعداد نتایج: 456925  

2013
Dana R Nossov M Torre Jorgenson Knut Kielland Mikhail Z Kanevskiy

Discontinuous permafrost in the North American boreal forest is strongly influenced by the effects of ecological succession on the accumulation of surface organic matter, making permafrost vulnerable to degradation resulting from fire disturbance. To assess factors affecting permafrost degradation after wildfire, we compared vegetation composition and soil properties between recently burned and...

2011
A. Bossy C. Grosbois S. Beauchemin A. Courtin-Nomade W. Hendershot H. Bril

At a watershed scale, sediments and soil weathering exerts a control on solid and dissolved transport of trace elements in surface waters and it can be considered as a source of pollution. The studied subwatershed (1.5 km) was located on an As-geochemical anomaly. The studied soil profile showed a significant decrease of As content from 1500 mg kg in the 135– 165 cm deepest soil layer to 385 mg...

2007
P. A. Cipriotti P. Flombaum O. E. Sala M. R. Aguiar

Current climate change models for arid ecosystems challenge our ability to understand the effects of droughts on plant population dynamics. In a sandy soil plant community from the Patagonian steppe, we studied soil water dynamics and its effects on grass regeneration. Our hypothesis was that a decrease in precipitation would not change soil water dynamics of the top soil layer where most of th...

2014
Abdoul Khadre Traore Philippe Ciais Nicolas Vuichard Benjamin Poulter Nicolas Viovy Matthieu Guimberteau Martin Jung Ranga Myneni Joshua B. Fisher

Few studies have evaluated land surface models for African ecosystems. Here we evaluate the Organizing Carbon and Hydrology in Dynamic Ecosystems (ORCHIDEE) process-based model for the interannual variability (IAV) of the fraction of absorbed active radiation, the gross primary productivity (GPP), soil moisture, and evapotranspiration (ET). Two ORCHIDEE versions are tested, which differ by thei...

2013
Xu Zhang Jian-Fei Lu

Dynamic analysis of a pile embedded in a half-space soil covered by a water layer is crucial for the designs of the pile foundations for bridges, docks and offshore platforms etc. In this paper, a coupled boundary element method (BEM) model is developed to evaluate the dynamic response of the pile. In the proposed model, the pile and half-space soil are treated as elastic media, while the water...

2013
Kristofer D Johnson Jennifer W Harden A David McGuire Mark Clark Fengming Yuan Andrew O Finley

Permafrost is tightly coupled to the organic soil layer, an interaction that mediates permafrost degradation in response to regional warming. We analyzed changes in permafrost occurrence and organic layer thickness (OLT) using more than 3000 soil pedons across a mean annual temperature (MAT) gradient. Cause and effect relationships between permafrost probability (PF), OLT, and other topographic...

Journal: :Journal of environmental quality 2012
Ana R García Roberto Maisonnave Marcelo J Massobrio Alicia R Fabrizio de Iorio

Accumulation of beef cattle manure on feedlot pen surfaces generates large amounts of dissolved solutes that can be mobilized by water fluxes, affecting surface and groundwater quality. Our objective was to examine the long-term impacts of a beef cattle feeding operation on water fluxes and manure leaching in feedlot pens located on sandy loam soils of the subhumid Sandy Pampa region in Argenti...

2009
Chunling Tang Thomas C. Piechota

This research investigates the interannual variability of soil moisture as related to large-scale climate variability and also evaluates the spatial and temporal variability of modeled deep layer (40–140 cm) soil moisture in the Upper Colorado River Basin (UCRB). A three layers hydrological model VIC-3L (Variable Infiltration Capacity Model – 3 layers) was used to generate soil moisture in the ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - پژوهشگاه مواد و انرژی - پژوهشکده سرامیک 1392

thermal barrier coatings (tbcs) are used to provide thermal insulation to the hot section components of gas turbines in order to enhance the operating temperature and turbine efficiency. hot corrosion and thermal shocks are the main destructive factors in tbcs which comes as a result of oxygen and molten salt diffusion into the coating. in this thesis atmospheric plasma spraying was used to dep...

2016
Ke Song Jianjun Yang Yong Xue Weiguang Lv Xianqing Zheng Jianjun Pan

In this study, a fixed-site field experiment was conducted to study the influence of different combinations of tillage and straw incorporation management on carbon storage in different-sized soil aggregates and on crop yield after three years of rice-wheat rotation. Compared to conventional tillage, the percentages of >2 mm macroaggregates and water-stable macroaggregates in rice-wheat double-c...

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