Total organic carbon fluxes of the Red River system (Vietnam)   总被引：1，自引：0，他引：1       下载免费PDF全文

Thi Phuong Quynh Le  Viet Nga Dao  Emma Rochelle‐Newall  Josette Garnier  XiXi Lu  Gilles Billen  Thi Thuy Duong  Cuong Tu Ho  Henri Etcheber  Thi Mai Huong Nguyen  Thi Bich Ngoc Nguyen  Bich Thuy Nguyen  Nhu Da Le  Quoc Long Pham 《地球表面变化过程与地形》2017,42(9):1329-1341

Riverine transport of organic carbon from terrestrial ecosystems to the oceans plays an important role in the global carbon cycle. The Red River is located in Southeast Asia where river discharge, sediment loads and fluxes of elements (carbon, nitrogen and phosphorus) associated with suspended solids have been dramatically altered over past decades as a result of reservoir impoundment and land use, population, and climate change. Dissolved organic carbon (DOC) and particulate organic carbon (POC) concentrations were measured monthly at four stations of the Red River system from January 2008 to December 2010. The results reveal that POC changed synchronically with total suspended solids (TSS) concentration and with the river discharge, whereas no clear trend was observed for DOC concentration. The mean value of total organic carbon (TOC = DOC + POC) flux in the delta of the Red River was 31.5 × 10¹³ ± 4.0 × 10¹³ MgC.yr^?1 (range 27.9–35.8 × 10¹³ MgC.yr^?1 which leads to a specific TOC flux of 2012 ± 255 kgC.km^?2.yr^?1 during this 2008–2010 period. About 80% of the TOC flux was transferred to the estuary during the rainy season as a consequence of the higher river water discharge. The high mean value of the POC:Chl‐a ratio (1585 ± 870 mgC.mgChl‐a^?1) and the moderate C:N ratio (7.3 ± 0.1) in the water column system suggest that organic carbon in the Red River system is mainly derived from erosion and soil leaching in the basin. The effect of two new dam impoundments in the Red River was also observable with lower TOC fluxes in 2010 compared with 2008. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献   

Factors affecting the stability of deep excavations in clay with consideration of a full elastoplastic support system     

Do  Tuan-Nghia  Ou  Chang-Yu 《Acta Geotechnica》2020,15(7):1707-1722

Acta Geotechnica - This study investigates the stability of internally braced excavations in thick, saturated clay using a finite element method with reduced shear strength. The support system was...  相似文献   

Tropical Cyclone in the North of the South China Sea as a Factor Affecting the Structure of the Vietnamese Current     

Vlasova  G. A.  Xuan  Nguyen Ba  Demenok  M. N.  Long  Bui Hong  Mau  Le Dinh  Dung  Nguyen Thi Thuy 《Izvestiya Atmospheric and Oceanic Physics》2020,56(4):390-400

Izvestiya, Atmospheric and Oceanic Physics - Tropical cyclones play a significant role in the formation of the hydrodynamic regime of the South China Sea, including its western part, which is...  相似文献   

Effects of warming on microbial communities in the coastal waters of temperate and subtropical zones in the Northern Hemisphere,with a focus on Gammaproteobacteria     

Dao Thi Anh Tuyet  Toshinari Tanaka  Rumi Sohrin  Do Manh Hao  Kazuyo Nagaosa  Kenji Kato 《Journal of Oceanography》2015,71(1):91-103

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Neogene freshwater stromatolites of Vietnam     

A. R. Geptner  V. V. Petrova  Phan Dong Pha  Nguyen Xuan Huyen  Le Thi Nghinh  Nguyen Minh Quang 《Doklady Earth Sciences》2012,443(2):436-438

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The Sin Quyen Cu–Fe–Au–REE deposit (northern Vietnam): composition and formation conditions     

I.V. Gas’kov  Tran Tuan Anh  Tran Trong Hoa  Pham Thi Dung  P.A. Nevol’ko  Pham Ngoc Can 《Russian Geology and Geophysics》2012,53(5):442-456

The Sin Quyen Cu–Fe–Au–REE deposit is localized in the Proterozoic deposits of the Phan Xi Pang zone, northern Vietnam. The mineralization is formed by lenticular and sheet-like bodies occurring concordantly with the host rocks. Seventeen orebodies have been recognized in the deposit, which form an ore horizon up to 140 m in total thickness, about 2 km in strike, and up to 350 m in dip. The ores are of simple mineral composition: Au-rich copper and iron sulfides (chalcopyrite, pyrite, pyrrhotite) and iron oxides (magnetite, hematite). Gold and silver are distributed unevenly in the ores: Their contents vary from hundredths and tenths of ppm to 1.8 ppm. Copper sulfide ores are the main concentrator of gold and silver. All ores are characterized by high REE contents, tens and hundreds of times exceeding the element clarkes. The highest contents have been revealed for Ce and La. Orthite is the main carrier of REE. No correlation between REE and ore elements of sulfide-oxide ores has been revealed, which points to the independent formation of the mineralization. Orebodies together with the host rocks underwent metamorphism at 500–600 to 630–685 °C and 3–7 kbar. The spatial association of the mineralization with amphibolites (metamorphosed basites) and the mineral composition of ores suggest that the Sin Quyen deposit is of Cyprian volcanogenic type.  相似文献   

The Khao Que-Tam Tao gabbro-granite massif, Northern Vietnam: A petrological indicator of the Emeishan plume     

A. G. Vladimirov  P. A. Balykin  Phan Luu Anh  N. N. Kruk  Ngo Thi Phuong  A. V. Travin  Tran Trong Hoa  I. Yu. Annikova  M. L. Kuybida  E. V. Borodina  I. V. Karmysheva  Bui An Nien 《Russian Journal of Pacific Geology》2012,6(5):395-411

New data obtained on the Khao Que-Tam Tao gabbro-granite pluton (Northern Vietnam) are discussed. It was established that this pluton was formed at the Permian-Triassic boundary (250.5 ± 3.2 Ma, ⁴⁰Ar/³⁹Ar isotopic age). Morphologically, it represents a hypabyssal fracture intrusion. The first stage was marked by the intrusion of the picrobasaltic melt, the differentiation of which resulted in the formation of the layered peridotite-gabbro series and the quartz-bearing monzodiorites and granophyres in its endocontact at the final stage. At the second stage, the Khao Que peridotite-gabbro massif was broken in its central part by a fault, along which the Tam Tao granodiorite-granite massif was localized. Numerical simulation using the COMAGMAT program for the basic system and geochemical estimates for the granite system allow the statement that the mafic and granitic melts evolved independently, and their final products were quartz-bearing monzodiorite and granophyre, on the one hand, and aplites and pegmatites, on the other hand. The compositional correlation of the Permian-Triassic magmatic associations in Northern Vietnam (the Nui Chua gabbro pluton and the Khao Que-Tam Tao gabbro-granite and Pia Bioc granite plutons) and in Southeast China (flood basalts) allows these complexes to be regarded as a part of a single large igneous province produced by the Emeishan plume activity.  相似文献   

Three-dimensional numerical simulation for mechanized tunnelling in soft ground: the influence of the joint pattern   总被引：1，自引：1，他引：0  

Ngoc-Anh Do  Daniel Dias  Pierpaolo Oreste  Irini Djeran-Maigre 《Acta Geotechnica》2014,9(4):673-694

The main purpose of this study was to provide a three-dimensional numerical model, which would allow the tunnel lining behaviour and the displacement field surrounding the tunnel to be evaluated. Most of the processes that occur during mechanized excavation have been simulated in this model. The influence of the lining joint pattern, including segmental lining joints and their connections, has in particular been taken into consideration. The impact of the processes during mechanized excavation, such as the grouting pressure and the jacking forces in the structural forces induced in the tunnel lining, has been presented. These values depend on the tunnel advancement. However, a negligible influence of the joint pattern on the ground displacement field surrounding the tunnel has been observed. Generally, a variation in the structural forces in successive rings along the tunnel axis has been found in a staggered segmental lining, indicating the necessity of simulating the joints in the tunnel lining and using a full three-dimensional numerical model to obtain an accurate estimation. In addition, the considerable influence of the coupling effect between successive rings on the lining behaviour has been highlighted.  相似文献   

Testing a conceptual hillslope recession model based on the storage–discharge relationship with the Richards equation     

Do‐Hun Lee 《水文研究》2007,21(23):3155-3161

The conceptual recession model based on the storage–discharge relationship was proposed to account for the unsaturated–saturated water storage interaction. The recession model was formulated by combining the constitutive storage–discharge relationship with the integral balance equation for unsaturated and saturated water storage. The functional form of the constitutive storage–discharge relationship was determined from the spatial integration of the Richards equation. The performance of the recession model was tested by comparing with the solution of the Richards equation for different simulation geometric shapes and soil types. The conceptual recession model incorporating the unsaturated–saturated water storage interaction was in good agreement with the recession response of the Richards equation. However, the recession model that neglected the unsaturated–saturated water storage interaction was comparable to the Richards equation only for soils with the weak interaction between unsaturated water storage and saturated water storage. This result suggests the important role of the unsaturated–saturated water storage interaction in the formulation of the recession process when the derivative of the functional relationship between the unsaturated water storage and saturated water storage becomes significant. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Predicting soil erosion hazard in Lattakia Governorate(W Syria)   总被引：1，自引：0，他引：1  

Mohammed Safwan  Khallouf Alaa  Alshiehabi Omran  Bao Pham Quoc  Thi Thuy Linh Nguyen  Nam Thai Van  Tran Anh Duong  Harsányi Endre 《国际泥沙研究》2021,36(2):207-220

The main objective of this study is to predict soil erosion in the Lattakia Governorate(WSyria)using the Water Erosion Prediction Project model(WEPP)and to compare the result with that of the RUSLE.Field survey and data collection were carried out,and 44 soil samples were analyzed.In addition,all the necessary input files were prepared for use in the WEPP model and RUSLE.Results show that more than of 80%of the locations studied experience slight to moderate erosion(less than 5 t/ha/y),whereas the rest of the locations experience severe soil erosion hazard.Moreover,the volume of runoff estimated by the WEPP model is in the range of 51e321 mm,and the R^2 between the simulated soil erosion and the predicted runoff reached 0.68.Interestingly,the R^2 between the WEPP model and RUSLE is 0.56,which indicates a good correlation between the two models.  相似文献