The profound impacts exerted by climate warming on the Tibetan Plateau have been documented extensively, but the biogeochemical responses remain poorly understood. This study was aimed at seasonal variations of total ...The profound impacts exerted by climate warming on the Tibetan Plateau have been documented extensively, but the biogeochemical responses remain poorly understood. This study was aimed at seasonal variations of total organic carbon(TOC) and total organic nitrogen(TON) in stream water at two gauging sections(TTH, ZMD) in the upper basin of Yangtze River(UBYA) and at fourgauging sections(HHY, JM, JG, TNH) in the upper basin of Yellow River(UBYE) in 2013. Results showed that concentrations of TON exhibit higher values in spring and winter and lower values in summer. TOC exhibits higher concentrations in spring or early summer and lower concentrations in autumn or winter. Seasonal variations of TOC and TON fluxes are dominated by water flux. In total, the UBYE and UBYA delivers 55,435 tons C of organic carbon and 9,872 tons N of organic nitrogen to downstream ecosystems in 2013. Although the combined flux ofTOC from UBYA and UBYE is far lower than those from large rivers, their combined yields is higher than, or comparable with, those from some large rivers(e.g. Nile, Orange, Columbia), implying that organic carbon from the Tibetan Plateau may exert a potentially influence on regional and/or global carbon cycles in future warming climate.展开更多
Motivated by the experimental result of an electronic circuit element"fractor",we introduce the concept of a dynamic-order fractional dynamic system,in which the differential-order of a fractional dynamic sy...Motivated by the experimental result of an electronic circuit element"fractor",we introduce the concept of a dynamic-order fractional dynamic system,in which the differential-order of a fractional dynamic system is determined by the output signal of another dynamic system.The concept offers an explanation for the physical mechanism of variable-order fractional dynamic systems and multi-system interaction.The properties and potential applications of dynamic-order fractional dynamic systems are further explored by analyzing anomalous relaxation and diffusion processes.展开更多
随着城市化的进程和人类活动强度的增加,过高的硝酸盐污染负荷对地表水水质安全构成极大威胁.当前针对地表水体的硝酸盐源解析仅强调了来源的季节性变化特征,而鲜见考虑降雨事件对区域污染源组成的影响.本文以扬州市江都区通扬运河为研...随着城市化的进程和人类活动强度的增加,过高的硝酸盐污染负荷对地表水水质安全构成极大威胁.当前针对地表水体的硝酸盐源解析仅强调了来源的季节性变化特征,而鲜见考虑降雨事件对区域污染源组成的影响.本文以扬州市江都区通扬运河为研究对象,利用氮氧同位素技术和基于R语言的稳定同位素模型(stable isotope analysis in R)定量评价了各类型污染源在不同降雨条件下对水体硝酸盐污染的贡献.结果表明:①通扬运河各区段污染物浓度具有很强的空间变异性.ρ(NO_(3)^(-))和ρ(NH_(4)^(+))具有相似的空间分布特征,表现为:中游区>下游区>上游区,中游区较高的城市化水平带来的人类活动加剧了氮污染的输入.②降雨增加了各河段污染物浓度的不确定性,降雨带来的冲刷和稀释效应总体上增加了水体中的ρ(NO_(3)^(-))、ρ(NH_(4)^(+))、ρ(Cl^(-))和ρ(SO_(4)^(2-)).③在无雨和低降雨的条件下,通扬运河水体NO_(3)^(-)主要来源于大气沉降(贡献率为27%~47%)和土壤有机氮(贡献率为21%~29%);在降雨事件影响下,化肥(贡献率为16%~34%)成为了最主要的污染源.降雨造成的污染源变化具有空间差异性,下游区(农业区)化肥和土壤有机氮贡献率的增加较中上游区更加明显.④下游区存在较强的反硝化作用,且低降雨条件下更容易发生硝化和反硝化.展开更多
The discrete version of solute transport equation for porous matrix depicted with the continuum model and the discrete fractured-network model are derived for fractured rocks with the Finite Volume Method （FVM）. The...The discrete version of solute transport equation for porous matrix depicted with the continuum model and the discrete fractured-network model are derived for fractured rocks with the Finite Volume Method （FVM）. The two models are coupled according to the continuity condition of hydraulic head and concentration and the conservation of flow flux and mass flux in the contact plane between porous matrix and fractures. Numerical results show that the simulated concentration of the coupling model based on the FVM agrees well with that from analytical solution, which demonstrates that the coupling model can effectively be applied to the simulation of solute transport in fractured rocks.展开更多
The movement of water flow in unsaturated fractured rock was investigated with the sandstone sample through experimental research and numerical simulation.The experimental results show that the arriving time of wettin...The movement of water flow in unsaturated fractured rock was investigated with the sandstone sample through experimental research and numerical simulation.The experimental results show that the arriving time of wetting front is delayed by the fracture,resulting in the increase of water saturation in the domain on the upstream side of the fracture,which will locally enhance water flow through the matrix.The numerical simulation with the finite volume method captures effectively these characteristics.The comparison between simulated and observed travel time and arriving time of wetting front shows that their difference are very small and the simulated results are in agreement with the observed results,which implies calibrated parameters are reliable and effective.Then according to the calibrated parameters,fractured models were established to examine how the change of large fractured aperture would affect the arriving time of wetting fronts,pressure heads and water saturation on the upstream and downstream sides of fracture.展开更多
基金funded by the National Natural Science Foundation of China (91647102, 41671053, 41201060, 41271035, 41261017)Open Foundations of State Key Laboratory of Frozen Soil Engineering (SKLFSE201411)+5 种基金Open Foundation of the State Key Laboratory of Cryospheric Sciences (SKLCS-OP-2017-03)Open Foundations of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering (2015490111)Fundamental Research Funds for the Central Universities (2014B16914)Special Fund of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering (20145027312)Academy of Finland (Decision number 268170), Hundred Talents Program, Chinese Academy of Sciences Key Research Program (KZZD-EW-13)the Fundamental Research Funds for the Central Universities (NO. B14020167)
文摘The profound impacts exerted by climate warming on the Tibetan Plateau have been documented extensively, but the biogeochemical responses remain poorly understood. This study was aimed at seasonal variations of total organic carbon(TOC) and total organic nitrogen(TON) in stream water at two gauging sections(TTH, ZMD) in the upper basin of Yangtze River(UBYA) and at fourgauging sections(HHY, JM, JG, TNH) in the upper basin of Yellow River(UBYE) in 2013. Results showed that concentrations of TON exhibit higher values in spring and winter and lower values in summer. TOC exhibits higher concentrations in spring or early summer and lower concentrations in autumn or winter. Seasonal variations of TOC and TON fluxes are dominated by water flux. In total, the UBYE and UBYA delivers 55,435 tons C of organic carbon and 9,872 tons N of organic nitrogen to downstream ecosystems in 2013. Although the combined flux ofTOC from UBYA and UBYE is far lower than those from large rivers, their combined yields is higher than, or comparable with, those from some large rivers(e.g. Nile, Orange, Columbia), implying that organic carbon from the Tibetan Plateau may exert a potentially influence on regional and/or global carbon cycles in future warming climate.
基金the National Natural Science Foundation of China under Grant No 11202066the National Basic Research Program of China under Grant No 2010CB832702the R&D Special Fund for Public Welfare Industry(Hydrodynamics,Project No 201101014).
文摘Motivated by the experimental result of an electronic circuit element"fractor",we introduce the concept of a dynamic-order fractional dynamic system,in which the differential-order of a fractional dynamic system is determined by the output signal of another dynamic system.The concept offers an explanation for the physical mechanism of variable-order fractional dynamic systems and multi-system interaction.The properties and potential applications of dynamic-order fractional dynamic systems are further explored by analyzing anomalous relaxation and diffusion processes.
文摘随着城市化的进程和人类活动强度的增加,过高的硝酸盐污染负荷对地表水水质安全构成极大威胁.当前针对地表水体的硝酸盐源解析仅强调了来源的季节性变化特征,而鲜见考虑降雨事件对区域污染源组成的影响.本文以扬州市江都区通扬运河为研究对象,利用氮氧同位素技术和基于R语言的稳定同位素模型(stable isotope analysis in R)定量评价了各类型污染源在不同降雨条件下对水体硝酸盐污染的贡献.结果表明:①通扬运河各区段污染物浓度具有很强的空间变异性.ρ(NO_(3)^(-))和ρ(NH_(4)^(+))具有相似的空间分布特征,表现为:中游区>下游区>上游区,中游区较高的城市化水平带来的人类活动加剧了氮污染的输入.②降雨增加了各河段污染物浓度的不确定性,降雨带来的冲刷和稀释效应总体上增加了水体中的ρ(NO_(3)^(-))、ρ(NH_(4)^(+))、ρ(Cl^(-))和ρ(SO_(4)^(2-)).③在无雨和低降雨的条件下,通扬运河水体NO_(3)^(-)主要来源于大气沉降(贡献率为27%~47%)和土壤有机氮(贡献率为21%~29%);在降雨事件影响下,化肥(贡献率为16%~34%)成为了最主要的污染源.降雨造成的污染源变化具有空间差异性,下游区(农业区)化肥和土壤有机氮贡献率的增加较中上游区更加明显.④下游区存在较强的反硝化作用,且低降雨条件下更容易发生硝化和反硝化.
基金supported by the Program for Changjiang Scholars and Innovative Research Team in University (Grant No.IRT0717)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministrysupported by the Natural Science Foundation of Hohai University (Grant No.2008433111)
文摘The discrete version of solute transport equation for porous matrix depicted with the continuum model and the discrete fractured-network model are derived for fractured rocks with the Finite Volume Method （FVM）. The two models are coupled according to the continuity condition of hydraulic head and concentration and the conservation of flow flux and mass flux in the contact plane between porous matrix and fractures. Numerical results show that the simulated concentration of the coupling model based on the FVM agrees well with that from analytical solution, which demonstrates that the coupling model can effectively be applied to the simulation of solute transport in fractured rocks.
基金Project supported by the Program for Changjiang Scholars and Innovative Research Team in Universities (Grant No. IRT0717)the Natural National Science Foundation of China (Grant No. 51079043)the Special Funds to Finance Operating Expenses For Basic Scientific Research of Central Colleges (Grant No. 2009B00514)
文摘The movement of water flow in unsaturated fractured rock was investigated with the sandstone sample through experimental research and numerical simulation.The experimental results show that the arriving time of wetting front is delayed by the fracture,resulting in the increase of water saturation in the domain on the upstream side of the fracture,which will locally enhance water flow through the matrix.The numerical simulation with the finite volume method captures effectively these characteristics.The comparison between simulated and observed travel time and arriving time of wetting front shows that their difference are very small and the simulated results are in agreement with the observed results,which implies calibrated parameters are reliable and effective.Then according to the calibrated parameters,fractured models were established to examine how the change of large fractured aperture would affect the arriving time of wetting fronts,pressure heads and water saturation on the upstream and downstream sides of fracture.
