洞庭湖不同水位高程下南荻(Triarrhena lutarioriparia)种群分布格局及生长动态

通过野外不同水位高程固定样地多次调查,结合方差/均值比率法研究了不同水位高程下洞庭湖湿地南荻(Triarrhena lutarioriparia)种群分布格局及生长动态.结果表明:(1)低程区土壤含水量显著高于高程区;低程区土壤颗粒组成与高程区相比有显著差异,低程区土壤为黏砂壤土,高程区为粉砂土;低程区土壤总有机碳、全氮、铵态氮和pH值等与高程区相比无显著差异,而其硝态氮、有效磷、全钾和速效钾含量低于高程区,全磷含量却恰好相反.(2)调查期间,南荻的分布格局随着植物的生长由均匀分布逐渐变为聚集分布,低程区聚集强度更大;(3)南荻的生物量和高度均随时间增长而迅速增加,且低程区的总生物量和增长量均高于高程区;南荻的密度和基径随时间增长而增加,之后趋于平稳,且低程区均高于高程区.结果分析表明,水位高程差异引起的土壤含水量的显著变化可能是影响南荻分布格局和生长动态最重要的因素.因此,适度地调控水位、增加土壤水分含量可能是控制南荻群落扩张的重要措施.     

火电厂粉煤灰的矿物磁性及其环境意义

火电厂排放的粉煤灰是重要的大气颗粒污染物之一,利用粉煤灰的磁性监测环境污染是新近发展的新手段。应用矿物磁测技术和X射线衍射对浙江省主要电厂排放的粉煤灰的矿物磁性特征和磁性矿物学,以及与重金属元素的关系进行了研究,结果表明粉煤灰具有较高的磁化率（X）、软剩磁（IRM20mT）和饱和等温剩磁（SIRM）值,粉煤灰频率磁化率（Xfd）的平均值为2．5％,磁性矿物以多畴（MD）颗粒存在,粉煤灰的剩磁矫顽力（BCR）在42～53mT之间。矿物测试结合X射线衍射分析表明粉煤灰中的氧化铁矿物以FeO4和Fe2O3-α为主,粉煤灰的磁化率与Fe、Mn、Pb、Zn、Cu、CA含量呈显著线性正相关,相关系数（r）分别是0．924,0．866,0．725,0．756,0．945和0．867,磁化率可作为粉煤灰中重金属元素含量的代用指标。     

Assessment of micro‐aggregation using laser diffractometry

In order to evaluate the influence of the measuring technique on the determination of (micro‐)aggregation in soil and sediment samples, results of grain size distributions of undispersed silty soil samples obtained by the sieve‐pipette method are compared with those obtained using a laser diffraction grain size analyser, the Coulter LS‐100. Reduced major axis relationships are calculated which may be used to convert Coulter LS‐100 results to those obtained by the sieve‐pipette method. The relationships obtained are very similar to the reduced major axis relationships established for dispersed silty soil samples. The results also show that the Coulter LS measurements have a systematic bias compared to the sieve‐pipette data. This implies that, if the percentage of (micro‐)aggregation is determined, the (interpretation of the) results will be strongly dependent on the measurement technique used. Using the calibration relationships that were established, nomographs can be developed to predict the level of sieve‐pipette (micro‐) aggregation from Coulter LS‐100 data. Copyright © 1999 John Wiley & Sons, Ltd.     

Swelling behaviour of expansive soil treated with fly ash–GGBS based binder

In this article, the potential of a binder developed by admixing fly ash and ground granulated blast furnace slag (GGBS) to stabilise expansive soils is evaluated. Laboratory tests included determination of free swell index, swell potential and swelling pressure tests of the soil/binder mixtures at different mixing ratio. The test results showed decrease in the swelling behaviour of the soil with increase in binder content. The percent swell–time relationship was observed to fit the hyperbolic curves enabling us to predict the ultimate percent swell from few initial test results. Addition of 1% of lime to the binder showed further improvement in reducing swelling. A good linear relationship is established between percent oedometer swell and modified free swell index (MFSI) for soil/binder mixtures without lime but the same has not been observed in the presence of lime. The compressibility characteristics of the soil/binder mixtures reduced nominally with increase in binder content but in the presence of lime, the compressibility reduced significantly. Binder used in this study has been found to be effective and economic to stabilise expansive soils with lesser amount of chemical additives such as lime.     

Use of fly ash with no water consumption for cold regions transportation infrastructure

The construction period in cold regions is very short due to problems related to excavation and use of frozen soils in embankment construction, which leads to excessive deformations upon thawing. Also, handling of compaction water is critical due to freezing temperatures. Coalburning thermal power plants are very common in cold regions to supply electricity. The inorganic part of the pulverized coal after burning produces fly ash, which is available in large volumes. Due to excavation difficulties and the poor engineering behavior of frozen soils in cold regions, the utilization of fly ash when it is readily available must be promoted. Any construction technique which utilizes alternative materials like fly ash and minimizes water consumption has a potential to extend the short construction season and even allow service and maintenance during extreme weather conditions. This paper presents two potential techniques to solve the moisture affinity of silt-sized materials like fly ash. One technique involves in-plant production of fly ash pellets using cold-bonding pelletization to manufacture aggregates of up to 40,000-μm diameter from 15- to 60-μm-diameter fly ash grains. Large disc pelletizers have annual production capacities of up to one million ton at a reasonable cost. The product has adequate strength for embankment construction even when no water is used and no compaction is applied. The second technique is an in situ mixing technique which uses snow instead of compaction water for fly ash. The snow is the main element in this technique to compact the embankment. Water is needed for the hydration reactions to form cementitious minerals in fly ash. The slower the hydration reaction, the greater the crystal growth of cementitious minerals. In the proposed technique, in situ snow is mixed with fly ash and is compacted on-site. The temperature increase due to the hydration reaction of fly ash upon contact with snow crystals provides water for continued long-term hydration, which results in high strength, a high void ratio, light weight, and high thermal insulation capability. The presented techniques have the potential to extend the short construction season in cold regions and will provide fill material, decreasing the need for excavation. Both techniques are well documented under laboratory conditions, the research results have been published, and the techniques are ready for field trials to assess implementability.     

粉煤灰增强回填碱渣工程特性的试验研究

碱渣与饱和卤水混合制成浆体回填到盐矿废弃盐腔可同时解决碱渣处理问题和地下废弃盐腔存在的地质隐患。回填碱渣强度是影响充填效果的重要因素。因此,为了提高回填碱渣强度,采用掺入粉煤灰制成复合碱渣对其强度特性进行改良。针对不同粉煤灰掺合比的碱渣开展了组成、力学和细观试验。研究结果表明：（1）掺入粉煤灰能明显改善碱渣的强度,使其黏聚力、内摩擦角都大幅提高,抗剪强度大幅增加;（2）粉煤灰掺合比越大,增强效果越明显,但强度并非随掺合比呈线性变化,对黏聚力而言,在0～20%内的掺合比下增加速度最快,而对内摩擦角则在20%～30%的掺合比区间增加最快,对抗剪强度而言,0～20%的掺合比内增加最明显;（3）粉煤灰掺入还可显著改善碱渣的压缩固结特性,使其固结系数大幅提高,从而提高碱渣固结速度,缩短充填工期,其中在0～10%的掺合比内对压缩固结特性改善最显著;（4）矿物组成分析表明,粉煤灰掺入改变了矿物组成,使得亲水性矿物含量急剧锐减,进而改变了其沉积特性。而细观分析则表明,粉煤灰掺入使碱渣从絮凝团细观结构变成了粉煤灰充当骨架的充填结构,且粒间支撑和拉联效应明显。从增强效果提高、压缩固结特性增强、控制成本和工期综合分析表明,最优掺合比为20%左右,建议工程中以不高于20%的掺合比作为实用掺合比即可取得较为理想的充填增强效果。该研究为揭示碱渣增强机制及废弃盐腔碱渣充填工艺优化提供了有益参考。     

四川万州中侏罗统上沙溪庙组粘土岩中火山灰的岩矿和地球化学证据

四川盆地东北缘万州地区中侏罗世上沙溪庙组产出稳定层状浅色粘土岩。利用X射线、X荧光光谱、等离子光谱（ICP）等方法对矿物成分、常量、微量和稀土元素进行了测试分析,粘土岩主要矿物为蒙脱石、伊利石和绿泥石。通过与澳大利亚后太古代平均页岩（PAAS）、北美平均页岩（NASC）、地壳粘土岩背景值以及其它具有代表性岩石的对比发现,本区粘土岩微量元素具有明显的低V,低Ti和低铁族元素的特点,高Al2O3／TiO2比值和低Ti／Th比值特征显著,某些层位具有明显的Eu负异常。推断本区粘土岩沉积物源具有火山灰和陆源碎屑的二元混合成因,各层位成分的差异显示了不同沉积时间内二者的混合比例发生变化。区域对比和地球化学资料显示火山灰可能来自于西部600km远的特提斯洋岛弧火山。     

鲐鱼灯光围网渔船水上集鱼灯水中照度分布及优化配置的理论计算

采用叠加法照度计算模式,根据一组鲐鱼灯光围网渔船中3艘不同渔船的水上集鱼灯布置参数,使用自行开发的水上集鱼灯水下光场计算系统,对各船的水中照度分布进行了计算,获得船舷右侧中部水深方向200 m范围内不同深度的照度,并使用Surfer 8.0软件绘制等值曲线图,结果表明:主灯船在总功率为180 kW的情况下,10 lx的等照度曲线水平方向最远在56 m左右,水深方向不超过20 m;离船水平距离40 m、垂直距离40 m处的照度约为0.01 lx。副灯船在总功率为120 kW的情况下,10 lx的等照度曲线水平方向最远在46 m左右,水深方向不超过18 m;离船水平距离33 m、垂直距离38 m处的照度约为0.01 lx。网船在总功率为40 kW的情况下,10 lx的等照度曲线水平方向最远在45 m左右,水深方向不超过15 m;离船水平距离30 m、垂直距离35 m处的照度为0.01 lx左右。从集鱼灯的配置情况来看,主灯船、副灯船与网船目前的配置均较好,但主灯船在灯距增大到0.26 m、灯高增大到5 m时可增加1.6%的有效水体体积,副灯船在灯距减少到0.28 m、灯高增大到5 m时可增加2.1%的有效水体体积,网船在灯距增大到0.64 m、灯高增大到9 m时可增加1.7%的有效水体体积。计算结果还表明,大幅度的增加光诱渔船的集鱼灯功率并不能很有效的提高该船的光诱范围。     

大掺量粉煤灰淤泥固化土的强度与耐久性研究

基于传统水泥和石灰固化处理方法,提出了利用大掺量低钙粉煤灰、水泥和石灰固化剂进行淤泥固化处理的方法,以期改善淤泥的强度和耐久性,达到淤泥和粉煤灰双重资源化利用的目的。通过一系列室内试验,探讨了该方法处理后固化淤泥的击实特征、强度特性、水稳性和耐久性。试验结果表明：淤泥固化后最优含水率有所降低、最大干密度则略有增加;弹性模量、无侧限抗压强度和抗拉强度均有不同程度的增加,水泥掺量越大,养护时间越长,强度和弹性模量越大;固化后淤泥水稳性得到明显改善;浸水软化和冻融循环导致固化土抗压强度显著劣化,冻胀融缩导致设计混合料的无侧限抗压强度减小约22%。     

隐伏金属矿床上升气流微粒特征、形成及迁移

结合地球化学和纳米科学技术的理论和研究方法,研究隐伏金属矿床有关微粒的形成、迁移和特征。对十多个金属矿床的研究表明,隐伏金属矿体地表沉积物中上升气流微粒样品有单个微粒和微粒聚合体,单个微粒形态有球状、近球状、不规则状、规则多边形、长柱状,微粒有晶质、非晶质和部分晶质。聚合体形态一般是不规则状、球状和近球状。它们的矿物成分主要有自然Au、自然Cu、氯化物、氧化物、硫酸盐、氢氧化物等。成矿元素Au、Cu可以自然金属或自然合金形式存在,Cu、Pb、Zn等成矿元素可以氧化物或硫酸盐等形式存在,也可以存在于氧化物、氢氧化物、氯化物、硫酸盐等微粒中作为杂质元素,这些是隐伏金属矿体的指示微粒。成矿期后,与隐伏金属矿体有关微粒主要形成于断层作用、氧化作用和生物作用。在上升气流中,微粒呈“布朗运动”。