华南热带水库丰水期浮游植物群落对氮、磷、铁加富的响应——以广东大沙河水库为例

富营养化是水生态系统主要的环境问题,自然条件下多种营养盐以组合形式进入水体,明确浮游植物群落对多种营养盐加富的响应对富营养化防治有重要意义。本研究以一座华南热带水库(大沙河水库)为例,分析了2021年枯水期(1—3月)和丰水期前期(4—6月)氮(N)、磷(P)、铁(Fe)和叶绿素a(Chl.a)浓度的变化趋势,并通过原位添加实验,解析浮游植物丰度和多样性对N、P、Fe加富的响应。结果表明:与1—3月相比,4—6月期间水体总磷浓度(TP)明显升高,总铁浓度(TFe)呈增加趋势但月度间波动较大,总氮浓度(TN)在4月最低,之后缓慢增加,期间Chl.a浓度从3月的5 μg/L快速增加到5月的29 μg/L。原位实验结果表明:浮游植物群落以蓝藻、绿藻和硅藻为主要组成,所有营养盐添加组浮游植物丰度均有增加,但只有NP同时添加时(NP和FeNP两组)生物量(以Chl.a表征)有显著升高;营养盐添加组细胞丰度的响应在门类和种类间差异明显,实验组组间群落结构和优势种类差异显著,所有处理组的群落多样性均明显高于对照组。N和P添加及其与Fe的联合添加(N、P、NP、FeN、FeP和FeNP)均导致蓝藻丰度升高,绿藻仅在NP添加组(FeNP组和NP组)显著升高且两组没有显著差异,硅藻仅在N和P单独添加组(N和P)显著升高。上述结果说明浮游植物生物量受N、P营养盐的共同影响而非单因子作用,N、P和Fe添加均影响群落结构和多样性,对水库富营养化的管理尤其是蓝藻水华防治应综合考虑3种营养盐的共同作用。     

地基GPS遥感大气水汽含量及在气象上的应用

简单介绍了地基GPS遥感大气水汽含量的原理以及GPS反演水汽信息的种类,比较了两种GPS数据解算水汽策略,分析了在解算过程中影响GPS水汽精度的因子。最后简述了GPS水汽在气象上应用的进展,并提出了以后需努力的方向。     

畸形波作用下双层水平板防波堤压力分布特性研究

基于物理模型试验,考虑畸形波参数、相对板宽、相对波高等影响因素,就畸形波对平顶双层水平板防波堤作用进行研究。首先对畸形波作用下双层水平板的波浪力分布特征进行了讨论,然后就最大波动压强、结构最大总垂向力与不规则波作用进行了对比分析。结果表明,畸形波作用下,双层水平板最大波动压力出现在前端迎浪区域附近,向尾端逐渐递减。双层水平板4个受力面的压力分布不同且有相位差,4个受力面的最大波动压力时间差约在0.1T_p~0.4T_p范围内变化。与不规则波作用比较,畸形波作用没有显著改变波压包络分布特征,但增大了波压包络强度值。试验范围内,就最大总力而言,两者最大总浮托力比值在1.06~2.45间变化;向下的最大总垂向力比值在1.22~2.07之间变化;就波动压力而言,其增大的幅度与畸形波参数α₁相关性最强,随α₁的增大而增大,在α₁=2.04~3.1试验范围内,畸形波作用时的最大压强比不规则波作用时可约增大20%~80%。就最大波吸力而言,两者的比值与畸形波参数α₄相关性最强,随α₄的增大而减小。在α₄=0.62~0.75试验范围内,最大波吸力强度的比值在1.61~0.87范围内变化。当α₄≤0.72时,畸形波作用时的最大波吸力大于不规则波作用时的最大波吸力;当α₄ > 0.72时则刚好相反。     

A proposal for the theoretical analysis of the interactive coupled effects between urbanization and the eco-environment in mega-urban agglomerations

Mega-urban agglomerations are strategic core areas for national economic development and the main regions of new urbanization. They also have important roles in shifting the global economic center of gravity to China. However, the development of mega-urban agglomerations has triggered the interactive coercion between resources and the eco-environment. The interactive coupled effects between urbanization and the eco-environment in mega-urban agglomerations represent frontier and high-priority research topics in the field of Earth system science over the next decade. In this paper, we carried out systematic theoretical analysis of the interactive coupling mechanisms and coercing effects between urbanization and the eco-environment in mega-urban agglomerations. In detail, we analyzed the nonlinear-coupled relationships and the coupling characteristics between natural and human elements in mega-urban agglomerations. We also investigated the interactive coercion intensities between internal and external elements, and the mechanisms and patterns of local couplings and telecouplings in mega-urban agglomeration systems, which are affected by key internal and external control elements. In addition, we proposed the interactive coupling theory on urbanization and the eco-environment in mega-urban agglomerations. Furthermore, we established a spatiotemporal dynamic coupling model with multi-element, multi-scale, multi-scenario, multi-module and multi-agent integrations, which can be used to develop an intelligent decision support system for sustainable development of mega-urban agglomerations. In general, our research may provide theoretical guidance and method support to solve problems related to mega-urban agglomerations and maintain their sustainable development.     

牛角塘伴生型镉矿床特殊的成矿环境

牛角塘伴生型镉矿床镉的富集程度高,比克拉克值高4~5个数量级,比工业品位高十几倍至上百倍。早寒武世清虚洞期牛角塘地区处于台缘滩丘环境,在清虚洞组中上部形成了藻丘建造,发育了含藻类、藻球粒、藻鲕粒、核形石和生物碎屑的白云岩,是该矿床最主要的容矿岩性单元。矿体普遍呈似层状、透镜状和脉状产出,矿体产状与容矿围岩的产状基本一致,矿体的分布受清虚洞组藻丘建造以及有利岩性组合的联合控制,具明显的层控、相控、岩控的特点。藻丘建造还可能提供了部分矿源。镉的超常富集、成矿与麻江古油藏的成藏演化具有一定的关系:一是牛角塘矿床成矿年龄为433~510 Ma,即加里东运动的中晚期,而加里东运动中晚期是麻江古油藏的油气活动时期,麻江古油藏的早期演化阶段与牛角塘镉矿的成矿期大体是重合的,成藏应略早于成矿,成矿是在古油藏液态烃仍然存在的情况下进行的,且成矿期有可能一直延伸至油藏被破坏以后;二是油藏流体为成矿提供具还原性质的成矿流体和部分硫源。特殊的岩相古地理环境和古油藏为牛角塘矿床镉的富集和成矿提供了有利条件。     

Hydrothermal plume mapping as a prospecting tool for seafloor sulfide deposits: a case study at the Zouyu-1 and Zouyu-2 hydrothermal fields in the southern Mid-Atlantic Ridge

Seafloor hydrothermal polymetallic sulfide deposits are a new type of resource, with great potential economic value and good prospect development. This paper discusses turbidity, oxidation–reduction potential, and temperature anomalies of hydrothermal plumes from the Zouyu-1 and Zouyu-2 hydrothermal fields on the southern Mid-Atlantic Ridge. We use the known location of these vent fields and plume data collected in multiple years (2009, 2011, 2013) to demonstrate how real-time plume exploration can be used to locate active vent fields, and thus associated sulfide deposits. Turbidity anomalies can be detected 10 s of km from an active source, but the location precision is no better than a few kilometers because fine-grained particles are quasi-conservative over periods of many days. Temperature and oxidation–reduction potential anomalies provide location precision of a few hundred meters. Temperature anomalies are generally weak and difficult to reliably detect, except by chance encounters of a buoyant plume. Oxidation–reduction potential is highly sensitive (nmol concentrations of reduced hydrothermal chemicals) to discharges of all temperatures and responds immediately to a plume encounter. Real-time surveys using continuous tows of turbidity and oxidation–reduction potential sensors offer the most efficient and precise surface ship exploration presently possible.     

Eurocode 8-compatible synthetic time-series as input to dynamic analysis

Nonlinear dynamic analysis of existing or planned structures often requires the use of accelerograms that match a target design spectrum. Here, our main concern is to generate a set of motions with a good level of fit to the Eurocode 8 design spectra for France. Synthetic time series are generated by means of a non-stationary stochastic method. To calibrate the input parameters in the stochastic approach, we select a reference set of accelerograms for a Eurocode 8 type B site category from the PEER Ground-Motion Database, which are then adjusted to the target spectrum through wavelet addition. Then, we compute nonlinear seismic responses of a soil column, including pore pressure effects, and brittle and ductile structures to the stochastic time-series, the natural accelerograms and time-series generated using stationary stochastic approaches. The results of these calculations reveal considerable variability in response despite the similarities in terms of spectral acceleration.     

陆态网络GNSS基准站阶跃偏移量的精确估计

通过对发生阶跃的GNSS基准站坐标序列谱指数的求解,表明了其具有有色噪声的特性,并对三分量分别建立了最优噪声模型,以此对GNSS基准站坐标的阶跃偏移量进行了精确估计,探明了地震和仪器更换对测站产生的精细影响。同时利用求解的阶跃偏移量对坐标序列进行修正,对获取连续性变化的测站坐标序列和获取精确的测站三维运动参数具有重要意义。