洪水期水位流量关系绳套曲线的直接拟合

受洪水涨落影响的水痊流量关系通常为时序型绳套曲线,现有的校正因数法在电算整编中存在一定的困难,通过对校正因数法公式的幂级数展开,提出了水位流量关系绳套曲线的计算机直接拟合数学方法,并对该法原理、步骤作了较详细的介绍。实例验证结果表明,该法能有效地模拟受洪水涨落影响的水位流量关系绳套曲线、且具有计算速度快,推流精度高等优点。     

Linear Stability of a Double Diffusive Layer of an Infinite Prandtl Number Fluid with Temperature-Dependent Viscosity

An infinite horizontal layer, with vertically stratified temperature and solute concentration, is considered in the case where the viscosity is exponentially dependent on temperature, and the Prandtl number is infinite. Its linear stability is investigated when the destabilizing thermal gradient acts against a stabilizing solute gradient. The analysis is performed using horizontal Fourier and vertical Chebyshev polynomial expansions. For the constant viscosity case, the laws well established in the free boundary configuration are seen to be directly suitable for the rigid one. In the variable viscosity case, characterised by a given viscosity contrast c, the scaling laws with c are settled extrapolating to the double diffusive situation the approach initiated by Stengel et al. (1982). In contrast with the constant viscosity case, the critical wave number is found to be strongly dependent on the solutal Rayleigh number in the marginal oscillatory obtained at large contrast values.     

Modification of North Pacific Intermediate Water around Mixed Water Region

The mixing processes in the Mixed Water Region (MWR) that lead to changes in the properties of North Pacific Intermediate Water (NPIW) have been studied using observational data sets obtained in May–June 1998. Neutral surfaces, the equation of water mass conversion rate on neutral surfaces and the equation of vertical velocity across neutral surfaces have been used to distinguish dominant processes by assuming the horizontal scale to be the streamer scale (under 100 km). The possibility of double diffusive convection is also discussed in relation to the density ratio. These results may be summarized as follows: (1) the difference between the potential density surface and the neutral surface may rise to −0.04 kg/m³ around the source water of NPIW; (2) horizontal diffusion causes strong modifications of the source water of NPIW; (3) the density range within which strong modification of the source water of NPIW occurs becomes dense from the northern part of MWR near the Oyashio Front to the southern part near the Kuroshio Front, and to the eastern part. Our modeling of these processes shows that cabbeling has effects on the density increment of the source water of NPIW in the northern and southern part of MWR. Double diffusive convection has effects on the density increment of the source water of NPIW, mainly in the northern part of MWR. The possible density increment due to cabbeling in these areas is estimated to be 0.01≈0.03 kg/m³. The possible density increment due to double diffusive convection is 0.01≈0.03 kg/m³. The total density increment due to cabbeling and double diffusive convection amounts to 0.06 kg/m³. This revised version was published online in July 2006 with corrections to the Cover Date.     

某高速公路下覆采空区的确定及危害程度探讨

某高速公路部分路段位于煤田浅部边缘地带,为有效评价煤矿采空区对高速公路路基及特大桥工程设施的潜在危害性,有必要查明区内采空区的分布范围和空间特征,确定采空区需要治理的程度,进而为采空区的优化治理方案提供决策依据。本文通过综合物探测量结合工程地质勘察,基本查明了煤矿采空区的分布规律和范围,首次在该区发现并确定了两条隐伏断层,详细分析了其在路基稳定性评价中的作用;明确了采空区的影响范围,从环境地球物理角度对煤矿采空区的治理提出了合理的建议。     

赤道东北太平洋沉积物间隙水中溶解有机碳的分布特征

沉积物间隙水中的溶解有机碳(DOC)是沉积物有机质矿化过程中的中间产物[1],沉积物中的有机质通过微生物水解和(厌氧)发酵等方式溶解成各类具有不同分子量的有机化合物,通常总称为溶解有机碳,并释放到沉积物间隙水中.而溶解有机碳又进一步被细菌等微生物所利用,最终被氧化为溶解无机碳,完成有机质的矿化过程.因此,沉积物间隙水中DOC的浓度是消耗和生成之间平衡的结果[1].已有的研究表明,沉积物间隙水中DOC的含量显著高于底层水体中DOC的含量,导致其向底层水体的扩散;近期的研究也表明,来自海底沉积物的DOC通量是底层水体中DOC的重要来源,是海洋有机碳储库中的重要组成之一[2~4].     

厦门同安湾红树林及临近光滩沉积物孔隙水中溶解活性磷和亚铁分布特征的对比分析

为了解红树林与光滩磷、铁地球化学行为的差异,借助薄膜扩散梯度技术(ZrO-Chelex DGT),对厦门同安湾红树林及临近光滩孔隙水中溶解活性磷(DRP)、Fe~(2+)浓度进行了原位测量,并采集了相应沉积物柱状样进行测定分析。结果表明:(1)Fe~(2+)与DRP呈现较好的线性正相关,说明磷的吸附/解吸与铁氧化还原循环有关;(2)在不同深度,光滩孔隙水中DRP浓度均高于对应深度红树林。在浅层,由于溪水的补给造成光滩的磷富集;在深层,红树植物根部吸收导致磷浓度下降,光滩有机质含量较多,矿化释放DRP使其浓度较高;(3)孔隙水中的Fe~(2+)浓度分布表明,红树林区域随着深度的增加,逐渐由好氧环境进入厌氧环境;而光滩沉积物氧化还原环境可能受到红树林的影响,孔隙水Fe~(2+)在垂向上波动分布。     

扩散性危机影响下公众心理韧性空间特征初探

当前危机管理研究多从公共管理、社会学和心理学等角度揭示恐慌发生的规律,鲜有研究揭示其地理时空特征。因此,从地理学的视角出发,利用百度搜索指数,探索公众恐慌心理的基本空间结构和变动特征,并尝试捕捉心理韧性的空间影响因素。主要得到3点结论:①在当前互联网高度通达的背景下,危机信息传播速度极快,由此引发的恐慌情绪已无明显空间扩散过程,而是瞬时传播至全国范围,且未出现明显的信息盲区;②距危机发生地的距离显著影响公众心理韧性,随着距离的增加,公众面对危机的恐慌心理没有呈现出距离衰减的空间规律,也不完全符合"心理台风眼"假说,而是呈现出以疫情较严重的地区为多个中心的涟漪状起伏的圈层结构,恐慌波动指数(PR Index)在1.112～1.947变动;③公众恐慌心理对危机信息的韧性差异,受信息类型和空间距离交互影响,表现为紊流状的空间异质结构。建议未来危机信息管理需要重视政策措施的空间区划,根据与危机发生地的空间关系,来决定重点发布何种信息,从而最大效度地减少公众恐慌。     

Grain‐scale dependency of metamorphic reaction on crystal plastic strain

The Breaksea Orthogneiss in Fiordland, New Zealand preserves water‐poor intermediate and mafic igneous rocks that were partially recrystallized to omphacite granulite and eclogite, respectively, at P ≈ 1.8 GPa and T ≈ 850°C. Metamorphic reaction consumed plagioclase and produced grossular‐rich garnet, jadeite‐rich omphacite, clinozoisite and kyanite. The extent of metamorphic reaction, identified by major and trace element composition and microstructural features, is patchy on the grain and outcrop scale. Domains of re‐equilibration coincide with areas that exhibit higher strain suggesting a causal link between crystal plastic strain and metamorphic reaction. Quantitative orientation analysis (EBSD) identifies gradual and stepped changes in crystal lattice orientations of igneous phenocrysts that are surrounded by homophase areas of neoblasts, characterized by high grain boundary to volume ratios and little to no internal lattice distortion. The narrow, peripheral compositional modification of less deformed garnet and omphacite phenocrysts reflects limited lattice diffusion in areas that lacked three‐dimensional networks of interconnected low‐angle boundaries. Low‐angle boundaries acted as elemental pathways (pipe diffusion) that enhanced in‐grain element diffusion. The scale of pipe diffusion is pronounced in garnet relatively to clinopyroxene. Strain‐induced mineral transformation largely controlled the extent of high‐T metamorphic reaction under relatively fluid‐poor conditions.     

A novel platform to evaluate the dampening of water and solute transport in an experimental channel under unsteady flow conditions

This paper presents a novel platform to study the dampening of water and solute transport in an experimental channel under unsteady flow conditions, where literature data are scarce. We address the question about what could be the smallest size of experimental platform that is useful for research, project studies, and teaching activities and that allows to do rational experiments characterized by small space occupation, short experimental duration, high measurement precision, high quality and reproducible experimental curves, low water and energy consumption, and the possibility to test a large variety of hydrograph scenarios. Whereas large scale hydraulic laboratories have focused their studies on sediment transport, our platform deals with solute transport. The objectives of our study are (a) building a platform that allows to do rational experiments, (b) enriching the lack of experimental data concerning water and solute transport under unsteady state conditions, and (c) studying the dampening of water and solute transport. We studied solute transport in a channel with lateral gain and lateral loss under different experimental configurations, and we show how the same lateral loss flow event can lead to different lateral loss mass repartitions under different configurations. In order to characterize water and solute dampening between the input and the output of the channel, we calculate dampening ratios based on peak coordinates of time flow curves and time mass curves and that express the decrease of peak amplitude and the increase of peak occurrence time between the input and output curves. Finally, we use a solute transport model coupling the diffusive wave equation for water transfer and the advection–diffusion equation for solute transport in order to simulate the experimental data. The simulations are quite good with a Nash–Sutcliffe efficiency NSE > 0.98 for water transfer and 0.84 < NSE < 0.97 for solute transport. This platform could serve hydrological modellers because it offers a variety of measured parameters (flow, water height, and solute concentration), at a fine time step under unsteady flow conditions.     

温带森林土壤溶液溶解性N2O和CO2含量特征及其影响机制

利用陶瓷头土壤溶液收集器采集2006年7月～2007年8月问长白山阔叶红松天然林不同深度(15cm和60 cm)土壤溶液,探讨应用气液萃取平衡-气相色谱法测定森林土壤溶液中溶解性气体N_2O和CO_2浓度的可行性,并利用此方法研究林地不同深度土壤溶液中两种气体含量特征及其影响机理.研究结果显示观测期内林地15 cm和60 cm深度土壤溶液中溶解性CO_2浓度的变化范围分别为5.26～10.71μg·mL~(-1)(C)和3.13～6.16 μg·mL~(-1)(C),溶解性N_2O浓度的变化范围分别为2.44～13.40 ng·mL~(-1)(N)和3.23～27.98 ng·mL~(-1)(N).阔叶红松天然林土壤溶液中溶解性CO_2和N_2O浓度均呈现出明显的季节性变化.春融后的降水促进了土壤溶液中溶解性N_2O产生,尤其在60 cm深度.与60 cm深度相比,林地15 cm深度溶液中溶解性CO_2浓度的季节性变化更明显,尤其在植物生长旺季.逐步回归分析显示,水溶性有机碳含量可以解释林地不同深度溶液中溶解性CO_2浓度变化的29%;水溶性有机氮含量可以解释林地60 cm深度溶解性N_2O浓度变化的34%.因此,水溶性有机碳和有机氮分别是长白山阔叶红松林土壤溶液溶解性CO_2和N_2O形成的重要因子.同时研究结果表明本文实验方法对于测定林地不同深度土壤溶液中溶解性N_2O和CO_2含量均有较好的适用性,连续三次萃取后所获得的气体浓度可有效反映溶液中的实际气体浓度.