砂泥岩互层裂隙地层的渗透性特征

本文分析研究了控制砂泥岩互层地层中裂隙渗透性的各种因素,提出了砂泥岩互层地层具有层状、带状和壳状三大渗透结构,并以黄河小浪底水库为例,通过三维有限元渗流计算,分析对比了三种不同类型的渗透结构对渗流场的影响,提高了对砂泥岩裂隙岩体渗透性分布规律的认识水平。     

裂隙水压力作用下砂泥岩互层库岸边坡稳定性分析

我国山区有很多砂泥岩软硬互层的顺层岩质边坡,传统的顺层岩质边坡失稳分析方法中的水压力分布形式存在一些缺陷,文中通过对岩体裂隙结构的分析,提出了新的水压力分布形式,不同裂隙结构时,应采用不同的水压力分布形式分析,并将其运用到砂泥岩互层的岩质边坡中。当坡体无张拉裂隙时,对于潜滑裂隙下端具有较大的泄水速度,即在裂隙中保持有稳定的水位的情形,以及当坡体无张拉裂隙且潜滑裂隙下端无泄水口时,两种水压力分布情况下所计算得到的最大水压力值相同,因此所计算得到的坡体安全系数相同。     

紫坪铺工程复杂结构层状岩质高边坡变形破坏模式研究

紫坪铺工程地质条件复杂，岩质条件差，由软硬相间的砂页岩互层组成，坝区有一向斜构造分布，组成了复杂结构的层状岩质高边坡，且开挖边坡较多，因此，边坡变形破坏模式研究具有重要的实际意义，通过对各边坡的岩体结构和边坡的变形破坏模式的研究，为边坡稳定性分析打下了可靠的基础。     

储能咸水层渗透性与传热性变化的诱导机制研究

该文通过三维砂箱可控模拟试验,结合胶体与表面化学相关理论,从介观尺度揭示了不同储能模式下引起含水介质黏粒重新分布的诱导机制,并探索了在复杂时空条件下咸水层空间结构的变化规律。试验结果表明,含水层渗透率不仅与回灌溶液温度、盐浓度的变化有关,而且含水介质渗透性与传热性变化规律在水平、垂直方向具有很强的空间非均质特征。在回灌混合低盐度溶液储热试验中,截至试验结束,500 mm-700 mm渗流单元上层相对渗透率降至53%,温度上升至45oC,下层相对渗透率最终降至48%,温度由15oC上升至42.9oC。     

珊瑚砂砾互层地基承载特性模型试验研究

岛礁在吹填过程中会形成珊瑚砂与珊瑚砾石相互交替的层状地基。为研究珊瑚砂砾交互地层地基的承载特性，通过室内模型试验，开展了纯砂、纯砾均质地基以及不同层厚比例砂砾互层地基的承载特性研究。试验结果表明：纯砂地基的承载力和变形模量随相对密实度的增大而增大，且密实地基的承载力明显高于中等密实地基；相同相对密实度下，纯砾地基的承载力和变形模量是纯砂地基的2倍以上；上砾下砂地基的承载力随砾层厚度的增大而增加，砾层具有一定的应力扩散作用，厚度越大，应力扩散越明显；上砂下砾地基的承载力随砾层埋深的减小而增大，地基下卧砾石层能使地基内一定深度处应力集中程度减弱，埋深越浅，减弱程度越大。试验结果对于确定砂砾互层地基的天然承载力及持力层选择具有重要意义。     

咸水灌溉下的土壤水盐运动规律

土壤旱季自然积盐再加咸水灌溉，土壤呈明显积盐趋势，试验结果表明，小定额灌溉，砂壤土的积盐程度较中壤土高；大定额灌溉，砂壤土的脱盐效果较中壤土为好。随着灌水定额的增加，从咸水带入土中的盐分渗滤到作物根层以下的盐量越多。     

软硬互层顺向岩质边坡失稳变形的离散元模拟

在工程建设中,软硬互层边坡十分常见,受岩石材料非均质性与层间软弱结构面的影响,该类边坡的变形破坏特征较为复杂,而相关研究较少.为此,该文以山软硬互层岩层结构为原型,基于离散元分析软件PFC,建立了软层裸露和硬层裸露2种模型,对软硬互层顺向岩质边坡失稳变形开展了数值模拟研究,结果表明:2种软硬互层顺向边坡失稳过程差异明显...     

深部咸水层CO2地质封存研究现状

从超临界CO2的物理性质出发,总结国内外深部咸水层封存CO2的机理研究、数值模拟、试验研究和工程应用方面所取得的主要成果。指出以往的研究主要集中于单一尺度研究均质地层封存CO2,较少考虑多尺度非均质性对咸水层封存CO2的影响。认为CO2在多尺度非均质深部咸水层中的运移与俘获特征将是碳捕捉封存技术的研究重点。     

聊城市部分井水变咸的原因及补救措施

聊城市地处鲁西平原,地下水水质在垂直方向上主要呈淡—咸—淡、咸—淡分布,约占总面积的79%,且咸水层厚度不均,矿化度在2~4.5g/L之间,为C1—Na型水。一旦井水变咸,应根据井的结构、管材、咸水入侵的位置采取相应的措施抓紧补救。1水变咸的原因井水变咸是由于含水层中咸水进入井内的结果。根据聊城市有关统计资料分析,出现咸水的原因可分为以下三种情况:(1)由于在开泵或停泵时,泵头与井管相互碰撞,随时间的增长,在井管与泵头接触处及其附近出现破管而进咸水。进水量的大小与破管的面积和咸水的补给源有关。这类井常表现为在开泵的几分钟内…     

陡倾砂板互层岩体中隧洞围岩变形研究

通过建立可反映岩体中砂岩与板岩组成、岩体倾角、岩体走向与隧洞轴线夹角等因素变化对岩体变形影响的砂板互层岩体本构模型,模拟了南水北调西线陡倾砂板互层岩体中隧洞掘进机开挖过程,初步分析了砂板互层岩体中隧洞围岩的变形及其对护盾式掘进机的影响。结果表明:埋深越大,围岩变形稳定过程越缓慢;岩体中板岩含量越高,围岩的前期变形越早、变形率越大,围岩的变形稳定过程也越长;对埋深较大且板岩含量较高的Ⅲ类岩体中的隧洞,应慎重采用护盾式掘进机开挖、管片衬砌的施工方案。     

Sediment greenhouse gases (methane and carbon dioxide) in the Lobo-Broa Reservoir, São Paulo State, Brazil: Concentrations and diffuse emission fluxes for carbon budget considerations

Carbon gases (methane, CH₄, and carbon dioxide, CO₂) were measured for the first time in sediments of the Lobo‐Broa Reservoir, near São Carlos in São Paulo State, Brazil. It is believed these are the first measurements of this kind in any of the many reservoirs located in Brazil. Even though the Lobo‐Broa Reservoir is classified as oligotrophic, the sediment gas concentrations were exceedingly high, ranging from 0.4–3 mmol L^?1 for CH₄ and 1–9 mmol L^?1 for CO₂. Both gases exceeded their in situ gas saturation values at these shallow water depths (7 m in central basin; 11 m at dam), resulting in numerous sediment bubbles. Organic matter was highly concentrated in the reservoir sediments, averaging 25.5% loss on ignition (LOI) (dam) to 26.9% LOI (central basin) for the 0–12 cm depth interval, with values as high as 29–30% LOI (12% organic carbon) in the surface 0–5 mm layer. The theoretical flux of dissolved pore water carbon gases to the sediment–water interface (SWI) averaged 3.4 mmol L^?1 m^?2 day^?1 CH₄ and 7.3 mmol L^?1 m^?2 day^?1 CO₂ for the surface 0–10 mm. From gas emission measurements at the water surface, it was calculated that 90% of CH₄ is consumed either at the SWI or in the water column, resulting in a loss of 0.31 mmol L^?1 m^?2 day^?1 of CH₄ to the atmosphere. However, only 20% of the total CO₂ gas transported across the water–atmosphere interface (36.3 mmol L^?1 m^?2 day^?1, or 1600 mg CO₂ m^?2 day^?1) was produced in the sediments. The remaining 80% of CO₂ probably comes from other carbon sources. With CH₄ oxidation in the aerobic water column, close to 30% of the carbon gas flux to the atmosphere could be accounted for by gas production of CO₂ and CH₄ in the sediments and their diffuse transport to the water column.     

海陆过渡界面浅层地下水可溶性SiO2的变化特征——以雷州半岛和海南岛滨海地区为例

硅为重要的地球化学元素,滨海地区作为地下水海陆过渡带,对地下水重要化学成分SiO_2的研究有助于进一步掌握海陆界面的水岩过程。在华南典型火山成因的雷州半岛和海南岛进行环岛浅层地下水连续取样和化学测试,分析模拟了可溶性SiO_2的变化、组成以及溶解平衡。结果表明:该地区地下水多为Na—Cl型,偏碱性,处于风化溶滤、蒸发浓缩状态或两者之间的过渡类型;地下水中可溶性SiO_2含量为2.80~106.0 mg/L,各测井变化较大,与周边环境条件有关,源自矿物溶解、海水入侵及其路径上的水岩作用;单个测井同一时段水样可溶性SiO_2含量呈波动变化,不同时段也变化明显;可溶性SiO_2以单分子正硅酸H4Si O4占据绝对优势,硅酸盐各类矿物呈现溶解、饱和、平衡的状态共存并且自身状态相互转化。总体来看,研究区地下水的饱和矿物种类比例偏高,因此,滨海地下水作为海陆过渡界面的高矿化度的开放体系,盐效应有促进不同矿物溶解或者饱和的作用。概而言之,上述可溶性SiO_2的水—岩过程受到多种因素影响,需要进一步加强研究。     

砂岩在化学腐蚀和冻融循环共同作用下力学特征劣化的试验研究

通过冻融循环试验的方法,研究砂岩在不同化学溶液下经冻融循环后的损伤劣化机制和力学特性,分析了砂岩在不同化学溶液中经历不同冻融循环次数后,单轴压缩和三轴压缩下力学性能的变化规律;初步分析了化学腐蚀和冻融循环共同作用对砂岩的损伤劣化机理;同时,定义了损伤变量来定量分析砂岩的损伤劣化程度。试验结果表明:浸泡在0.1 mol/L(H_2SO_4)、0.1 mol/L(NaOH)和p H=7.0蒸馏水中,随着冻融循环次数的增加,砂岩试样的峰值强度和弹性模量均呈指数函数劣化,而其轴向峰值应变却呈指数函数增加。砂岩的损伤程度随着冻融循环次数的增加而逐渐增大;在H_2SO_4溶液中砂岩的损伤劣化程度大于NaOH和pH=7.0蒸馏水;H_2SO_4溶液加剧了砂岩的冻融损伤劣化,而0.1 mol/L(NaOH)溶液对砂岩试样的冻融损伤劣化却有一定的抑制作用。化学腐蚀和冻融循环共同作用下,水化学溶液虽然在一定程度上缓解冻融循环所引起岩石的损伤劣化,但同时岩石遭受着水化学溶液的腐蚀作用;水化学溶液与冻融循环的共同作用对岩石的损伤劣化是相互促进的,共同影响着砂岩的损伤劣化。     

Research progress of water eutrophication induced by climate changeEI北大核心CSCD

对大气CO₂浓度升高及气候变化诱发水体富营养化的驱动机制进行了综述。CO₂浓度升高促进浮游植物大量增殖;水温升高引起水体分层现象加剧,底层缺氧更加严重,沉积物营养盐释放加剧,促进浮游藻类的生长;降水变率、强降水发生的概率增加,会加剧土壤中氮的流失,导致水体营养盐浓度增加;太阳辐射减弱会导致水下光照减少,加速沉水植物的衰亡,促进浮游植物的生长,进一步恶化水下光照环境;风速降低会延长水体分层时间,提高水体稳定性,造成底层缺氧,加大沉积物营养盐的释放;台风等热带气旋引发的强风浪会促进水体中氮、磷等营养盐释放,有利于蓝藻细胞团增大,获得更大的浮力,带来的暴雨还会将周围营养盐携带入水体,促进藻类生长。以上这些气候变化主要特征还会相互作用,加大水体富营养化的发生风险,继而对整个水生生态系统产生一系列间接影响。指出了未来研究的重点:气候变化对水生生态系统的影响;气候变化主要特征之间系统相互作用的机理;内外源污染与气候变化对水体富营养化的贡献率;水生生态系统应对气候变化的对策等。     

夏季朱衣河二氧化碳分压分布特征及影响因素分析

为研究夏季三峡水库支流库湾-朱衣河的水体二氧化碳分压(p(CO_2))分布特征及影响因素,于2016年7月进行两次分层采样。根据水体的碳酸平衡原理和亨利公式计算水体p(CO_2)并利用水体中超额的二氧化碳分压(E_(p(CO_2)))和表观耗氧量(AOU)的比值(E_(p(CO_2))/AOU)表征生物好氧呼吸作用对p(CO_2)影响程度,研究结果为:上游表层水体的p(CO_2)变化范围大概在5.14~53.67 Pa,受使水体中H+减小的浮游植物光合作用影响较大,导致碳酸盐平衡向右移动,水体中CO_2极不饱和;5 m以下分层水体的p(CO_2)随着水深有变大的趋势,变化范围最低是26.04 Pa,最高是117.28 Pa,而?E_(p(CO_2))/?AOU值高达1.04~2.91,远高于评估上限值,其主要受外源碳汇入影响明显;河口的p(CO_2)大概为39.93 Pa,?E_(p(CO_2))/?AOU的值为0.64±0.01,受生物好氧呼吸作用影响显著;整体的p(CO_2)与温度(T)、pH、溶解氧(DO)、叶绿素ɑ(Chl-a)、硝氮(NO_3~-)存在显著的负相关关系,与浊度(TD)有显著的正相关性,与溶解有机碳(DOC)无显著相关性。     

Groundwater discharge drives water quality and greenhouse gas emissions in a tidal wetland

Wetlands play an important role in the global carbon cycle as they can be sources or sinks for greenhouse gases. Groundwater discharge into wetlands can affect the water chemistry and act as a source of dissolved greenhouse gases, including CO₂ and CH₄. In this study, surface water quality parameters and CO₂ and CH₄ concentrations were evaluated in a tidal wetland (Hunter Wetlands National Park, Australia) using time series measurements. Radon (²²²Rn), a natural groundwater tracer, was used to investigate the role of groundwater as a pathway for transporting dissolved CO₂ and CH₄ into the wetland. In addition, water-to-air CO₂ and CH₄ fluxes from the wetland were also estimated. The results showed a high concentration of radon in wetland surface water, indicating the occurrence of groundwater discharge. Radon concentration had a strong negative relationship with water depth with a determination coefficient (R²) of 0.7, indicating that tidal pumping was the main driver of groundwater discharge to the wetland. Radon concentration also showed a positive relationship with CO₂ and CH₄ concentrations (R² = 0.4 and 0.5, respectively), while the time series data revealed that radon, CO₂, and CH₄ concentrations peaked concurrently during low tides. This implied that groundwater discharge was a source of CO₂ and CH₄ to the wetland. The wetland had an average water-to-air CO₂ flux of 99.1 mmol/(m²·d), twice higher than the global average CO₂ flux from wetlands. The average CH₄ flux from the wetland was estimated to be 0.3 mmol/(m²·d), which is at the higher end of the global CH₄ flux range for wetlands. The results showed that groundwater discharge could be an important, yet unaccounted source of CO₂ and CH₄ to tidal wetlands. This work has implications for tidal wetland carbon budgets and emphasizes the role of groundwater as a subsurface pathway for carbon transport.     

Comparisons between the chemical compositions of lake water,inflowing river water,and lake sediment in Nam Co,central Tibetan Plateau,China and their controlling mechanisms

The chemical composition of lake water and inflowing river water was investigated in Nam Co (lake), Tibetan Plateau, in September 2005. Lake water samples (n = 76) were collected at different depths along a south–north transect of the eastern part of the lake while water samples were collected from 69 rivers flowing into the lake; a sediment core was collected at 64 m midway along the water survey transect to investigate salt precipitation. Na⁺ and Ca²⁺ were the dominant cations, accounting for 76.2% and 60.6% of the lake and river water cations, respectively while HCO₃⁻ was the dominant anion accounting for 70.8% and 93.4% of lake and river anions, respectively. CaCO₃ precipitation from the water column decreased Ca²⁺ in the lake water, with the relative proportion of other ions increasing significantly. Evaporation–crystallization processes largely control Nam Co lake-water chemistry, while rock weathering is the dominant processes influencing the chemistry of river water; carbonate and silicate weathering are the major sources of ions in these rivers.     

咸水在黏性土中迁移转化的试验研究

采用衡水地下水科学试验场浅层钻孔土样进行室内一维土柱渗流试验,并用地球化学模拟方法探讨黏性土对咸水迁移转化的控制机理。结果表明:黏性土对咸水迁移有一定的阻隔作用,1号土柱对Na+的阻滞作用以吸附为主,2号土柱对Na+的阻滞作用由吸附和阳离子交换共同影响;1号和2号土柱的阻盐率分别为49.8%和54.5%;1号和2号土柱中黏性土的阻滞因子R1和R2分别为1.54和3.78;咸水迁移过程中,控制水岩相互作用的主要因素是岩盐的沉淀,石膏、方解石的溶解,Mg2+、Ca2+与Na+之间的离子交换。     

Telemetry evaluation of carbon dioxide as a behavioral deterrent for invasive carps

Carbon dioxide (CO₂) mixed into water is being explored as a possible management strategy to deter the upstream movements of invasive carps through navigation locks and other migratory pinch-points. This study used two-dimensional acoustic telemetry to assess the effectiveness of dissolved CO₂ as a chemosensory deterrent to two carp species in a large U-shaped pond. Free-swimming movements of telemetered bighead carp (Hypophthalmichthys nobilis) and grass carp (Ctenopharyngodon idella) were documented 24 h before treatment and 24 h during treatments at 60, 121 and 213 mg/L CO₂ (mean concentrations in pond water). Several behavioral endpoints were then quantified and compared to evaluate deterrence efficacy. In general, results showed that both carp species responded similarly to CO₂ treatments. Carps consistently relocated into areas away from the injection site and made fewer attempts to re-enter CO₂ treated areas. On average, CO₂ treatments reduced mid-line crosses between untreated and treated sides of the pond by 58% at 121 mg/L CO₂ and 78% at 213 mg/L CO₂ relative to normal swimming movements recorded before treatment. Fish swim speeds increased significantly when inside the CO₂ plume during treatments during 213 mg/L CO₂ trials relative to swim speeds outside the plume, possibly indicative of active searching and avoidance responses. Overall, this study found that CO₂ altered the behavior of bighead carp and grass carp. Natural resource agencies could consider the CO₂ concentrations identified in this study to inform future applications to deter invasive carps from locations where they are at-risk to move upstream.     

基于SWAP模型的河套灌区向日葵农田土壤水盐通量模拟

为了探究河套灌区节水实施现状条件下农田土壤水盐动态变化规律,利用向日葵田间试验观测资料,对SWAP模型进行参数率定和验证,并利用该模型模拟向日葵生长条件下0～100 cm土层土壤水盐通量及水盐平衡状况。研究结果表明：在灌溉阶段,向日葵根系层土壤水分主要向下渗漏,水分通量和盐分通量为负,土壤盐分被淋洗;在非灌溉阶段,地下水向上补给向日葵根系层土壤,水分通量和盐分通量为正,根系层土壤积盐。2019、2020年模拟期间水分通量累计量分别为52.5、60.6 mm,盐分通量累计量分别为-4.5、-4.9 mg/cm²,0～100 cm土层土壤盐分通量分别增加了7.5、7.1 mg/cm²。向日葵现状灌溉条件下0～100 cm土层土壤积盐,可能产生土壤次生盐碱化的风险,向日葵生育期结束后需要进行秋浇淋洗盐分来保证下一年度向日葵的正常生长。