共查询到18条相似文献，搜索用时 140 毫秒
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甘肃夏河-青海同仁一带位于西秦岭造山带的西段, 区内中二叠世大关山组发育, 经本次研究为生物礁灰岩.大关山组产出丰富的古生物化石, 主要种类为串管海绵, 纤维海绵, 苔藓虫, 钙质藻类, 复体珊瑚,
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高氯酸盐( )是一种小分子量、有毒的无机络阴离子,普遍存在于环境中。由于其分子大小与碘离子相似,会干扰人体甲状腺的正常功能,因此其环境污染问题引起了广泛的关注。本文选取污染场地的天然河沙为试验材料,主要通过柱实验对地下水中 自然衰减过程进行研究,考察了铁氧化物、 对 自然衰减过程产生的影响。结果表明,高氯酸盐自然衰减过程主要由微生物驱动,天然河沙可去除2 mg/L的 ,但其过程缓慢且还原量有限,长期去除率不超过10%,其限制因素为缺乏电子供体;铁氧化物可以促进 自然衰减,但当溶解性铁的浓度低于5.5 mg/L时,衰减过程开始受到影响;地下水中的 会抑制 的降解,当 低至10 mg/L或以下时, 才开始明显降解。 相似文献
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苏里格气田苏77区块二叠系下统山西组二段发育自北向南的曲流河,各气层组沉积特征比较一致。但是山西组二段山 2 1 山 2 2 山 2 3 山 2 1 山 2 2 山 2 3 山 2 1 山 2 2 山 2 3
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为研究震后强降雨条件下沟道泥石流产生的力学机制及水力学机理,以都江堰市龙池镇银洞子泥石流沟为研究对象,构建坡面松散堆积体地下水位变化水力模型,按照水力学渗流理论,分析了震后泥石流形成区坡面松散堆积体内潜水位变化的特征和规律,定量研究了动静水压力对坡体的作用特点。根据理论分析、实例验证与物理模拟试验的研究结果,获得了对坡面松散物源启动力学机理、启动临界条件及启动模式的深刻认识: ①在强降雨激发作用下,随着坡体内潜水位不断升高,水力条件不断恶化,最终导致坡面松散堆积体发生失稳破坏; ②堆积体内潜水位高度是坡面面积(S I T D S I H ( P ) ( G d )
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C、N、S、Fe是地下水中控制氧化-还原反应的主要元素,淤泥是黏土的演化初期,淤泥演化为黏土过程中会影响含水层水量水质,可能会造成地下水污染;其中的水岩相互作用可以概化为C-N-S-Fe-H2O体系的相互作用。淤泥演化过程的实质是淤泥在压力的作用下孔隙度不断变小,逐渐固结成岩;淤泥内部不断发生生物地球化学反应,C-N-S-Fe-H2O体系驱动各种物质的形态结构不断发生改变,其中加压速率和加压模式会影响淤泥里的C、N、S、Fe重要组分固液相的转化。本研究运用自主研发设计的增压装置,探究在3种加压速率(0.04 MPa/12 h、0.04 MPa/24 h、0.04 MPa/36 h)和加压模式(0.040.02 MPa/12 h、0.04 MPa/12 h、0.040.06 MPa/12 h)的情况下,固体介质中C、N、S、Fe向孔隙水释放的规律。结果表明:(1)匀速加压速率越慢,加压初期溶解性有机碳(DOC)、 释放速率越快, 和Fe2+浓度变化增大;DOC、 、 、Fe2+释放总量越多。(2)不同的加压模式,加速加压(0.040.06 MPa/12 h)下 、Fe2+的浓度波动较大;DOC、 、 和Fe2+的总释放量为加速加压(0.040.06 MPa/12 h)大于匀速加压(0.04 MPa/12 h)。(3)加压过程中,DOC和 呈显著正相关,改变加压速率会改变DOC, 、 和Fe2+的相关性。本研究表明改变加压速率和加压模式会对DOC、 、 和Fe2+的释放速率、释放总量和C、N、S、Fe的转化造成影响,其本质为氧化-还原反应和水岩相互作用的强弱发生了变化;本研究为地质演化过程中压力导致的主要元素变化提供了新的认识,认识到了隔水层会影响含水层的水质和水量,为原生劣质地下水的成因和地下水污染防治提供了新思路。 相似文献
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大气硝酸盐（包括颗粒态硝酸盐和气态硝酸）是一种重要的含氮物质,在北冰洋氮的生物地球化学循环中起着重要作用。然而,目前关于北冰洋上大气硝酸盐形成机制的研究较少,限制了对该地区氮氧化物（NOX）到硝酸盐相关大气化学过程的理解。作为2012年夏季中国第五次北极科学考察的内容之一,本研究采集了科考航线上的大气气溶胶样品,并对北冰洋航段（62.3°~74.7° N）上样品中硝酸盐的氮氧同位素（δ15N,δ17O和δ18O）进行了分析以研究该区域大气硝酸盐的形成过程。观测到的Δ17O（NO
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为了分析火山渣吸附去除地下水中大肠杆菌噬菌体作用特性,通过室内实验,考察火山渣吸附地下水中vB_EcoM-ep3大肠杆菌噬菌体效果,同时用等量沸石与石英砂做对照,进一步分析地下水中水化学因素(Fe2+、Fe3+、Mn2+、 、 、 、 、Ca2+、Mg2+、 、 和pH值)对其吸附效果影响;通过微观检测技术,分析大肠杆菌噬菌体生物学特性和火山渣吸附前后微观结构变化。研究结果表明:火山渣吸附效率优于沸石和石英砂,最大饱和吸附量达到2.245×105 pfu/g;水化学因素对火山渣吸附效果影响存在差异性,其中Fe2+、Fe3+起到促进作用, 、三氮和碱度起到抑制作用,低浓度Mn2+( <10 mg/L)和Ca2+( <100 mg/L)起到轻微促进作用,超过该浓度则表现为抑制作用;pH值对火山渣吸附效果影响较大,pH值越大,吸附效果越差。vB_EcoM-ep3大肠杆菌噬菌体头部为等边六角形,全身直径约为(53±2) nm,尾部长约为(107±3) nm,由尾管和尾丝组成,可伸缩。具有蜂窝状结构的火山渣吸附大肠杆菌噬菌体后表面孔隙大部分被填充。 相似文献
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The distribution of frozen soil in our country is very broad, and the area of permafrost alone accounts for 22. 4% of the total land area. As a special kind of soil, frozen soil has many properties that thawing soil does not have due to the influence of ice cement in the soil. Among the many properties of frozen soil, the deformation and strength of frozen soil are the basic problems affecting engineering construction in frozen soil areas. The spherical template indenter test is widely used in the test of the mechanical properties of frozen soil because of its simple test process and relatively accurate test results. Compared with the conventional triaxial test or direct shear test, the test process of the spherical template indenter test is simple and easy to implement, the test period is short, and the sample preparation requirements are low. The advantage of effective cohesion is more significant. Therefore, based on the spherical template indenter test of the frozen soil, this paper estimates the strength and mechanical index of the soil through the indentation depth of the spherical template indenter test, and establishes the relationship between the force of the sample and the indentation depth of the indenter test. The specific test method is as follows:take the water-saturated frozen sandy soil made of different particle size groups(the moisture content of the sample is affected by the particle size in the saturated state)as the research object, study the variation law of the depth of the frozen soil sample pressed into the soil by the spherical indenter with time under the conditions of different fixed loads. By comparing and referring to the frozen sands of each particle size group, the long-term equivalent cohesion of the frozen sands of different particle size groups is summarized. The change law of force(long-term shear strength)with time, and the research method of elastic mechanics to solve space problems, summed up the mutual conversion between the depth St of spherical template indenters pressed into frozen sand samples under different fixed load test conditions relation. The research results show that the long-term shear strength of frozen sand based on the spherical mold test is positively correlated with its particle size. At the same time, since the ice content of frozen soil samples is proportional to its particle size, the long-term shear strength of frozen sand is also proportional to the test. The ice content of the sample increases year-on-year;the long-term shear strength of the frozen sand is related to the maximum contact pressure on the contact surface between the frozen soil and the indenter during the test, which can be expressed as Ct = γq0. The size of the relationship coefficient γ is inversely proportional to the diameter of the spherical indenter. In this paper, the spherical indenter is selected as 22 mm, and γ=3. 82×10-3. By establishing the relationship between the maximum contact pressure q0 and the long-term shear strength Ct When the maximum contact pressure q0 is the same under different fixed loads, the long-term shear strength Ct is also the same. According to this, the depth curve and the freezing depth of the frozen sand pressed into the soil by the spherical indenter over time under different fixed loads can be converted. Long-term shear strength curve of frozen sandy soil with time. It has been verified by experiments that the conversion curve of the depth of the indenter pressed into the soil with time under a fixed load of 7. 0 kg is highly consistent with the measured curve of the depth of the indenter pressed into the soil with time under a fixed load of 5. 1 kg and 7. 0 kg. © 2022 Nanjing Forestry University. All rights reserved. 相似文献
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210Po and 210Pb measurements of soils delineated uranium anomalies at three out of four test sites in Ontario, Canada. Measurements were made of 210Po in solutions produced by both complete digestion and partial leaching of soil samples. Direct plating of 210Po onto metal plates was followed by measuring the alpha activity. Subsequent plating of 210Po in-grown from 210Pb in solution several months later confirmed the anomalies.The 210Po and 210Pb anomalies at three of the test sites coincided with 226Ra and 222Rn anomalies. Samples from the fourth uranium occurrence associated with a known 222Rn anomaly failed to show either a 226Ra anomaly on the one hand, or 210Po or 210Pb anomalies on the other. This suggests that the 210Po and 210Pb anomalies were probably produced by the decay of 226Ra contained within secondary dispersion haloes.Although anomalies due to the 210Po and 210Pb products of 222Rn have now been documented, prospecting methods based on their use as direct tracers of the migration paths of 222Rn require much further development. 相似文献
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210Po and 210Pb measurements of soils delineated uranium anomalies at three out of four test sites in Ontario, Canada. Measurements were made of 210Po in solutions produced by both complete digestion and partial leaching of soil samples. Direct plating of 210Po onto metal plates was followed by measuring the alpha activity. Subsequent plating of 210Po in-grown from 210Pb in solution several months later confirmed the anomalies.The 210Po and 210Pb anomalies at three of the test sites coincided with 226Ra and 222Rn anomalies. Samples from the fourth uranium occurrence associated with a known 222Rn anomaly failed to show either a 226Ra anomaly on the one hand, or 210Po or 210Pb anomalies on the other. This suggests that the 210Po and 210Pb anomalies were probably produced by the decay of 226Ra contained within secondary dispersion haloes.Although anomalies due to the 210Po and 210Pb products of 222Rn have now been documented, prospecting methods based on their use as direct tracers of the migration paths of 222Rn require much further development. 相似文献
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A method is described for bringing a sediment sample into solution and subsequently carrying out analysis for 210Pb, 226Ra and 137Cs. Silica is removed from the sample by cyclic HNO3HF treatments. 137Cs is separated from 210Ra in a carbonate fusion, extracted by absorption on ammonium molybdophosphate, precipitated directly with BiI3 in presence of citric acid, and β-counted. 210Pb and 226Ra are separated out by 70–75% HNO3 precipitation. Further purification and mutual separation of the two radionuclides is achieved by solvent extraction and anion-exchange techniques. 210Pb and 226Ra are determined by β- and α- counting of their chromate precipitates, respectively, after allowing suitable ingrowth periods for their daughters. The procedural steps effectively eliminate possible interference from other natural or fall-out radioactivities. 相似文献
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