Modeling rhizofiltration: heavy-metal uptake by plant roots

The discovery of phytoaccumulation potential of plant species has led to its application for remediation of heavy-metal-contaminated soil and wastewater, which is termed as phytoextraction/rhizofiltration. For prediction, analysis, planning and cost-effective design of such systems, mathematical models not only are used as a screening tool but also provide optimal parameters like harvesting time, irrigation schedule, etc. Several laboratory and field scale studies have been carried out in the past, and mathematical expressions have been developed by various researchers for different phenomena like metal adsorption in soil, plant root growth with time, moisture and metal uptake by plant root, moisture movement in unsaturated zone, soil moisture relationship, etc. The complete design of any such phytoremediation program would require the knowledge of behavior of heavy-metal movement in soil, water and plant root system. In this paper, a model for simulating heavy-metal dynamics in soil, water and plant root system is developed and discussed. The governing non-linear partial differential equation is solved numerically by implicit finite difference method using Picard's iterative technique, and the formulation has been illustrated using a characteristic example. The source code is written in MATLAB.     

内蒙古某灌域表层土壤六氯环己烷空间分布特征及影响因素

为修复灌区内土壤有机氯农药污染，降低六氯环己烷对土壤环境的危害，对内蒙古某灌域表层土壤进行采样，利用气相色谱测定50个土壤样品中六氯环己烷及其异构体的含量，并利用ArcGIS空间分析技术确定表层土壤中六氯环己烷的分布状况。样本中六氯环己烷的检出率为96%，各样本中六氯环己烷的浓度范围为未检出~23.0 ng/g，平均浓度为4.4 ng/g。4种异构体含量平均值顺序为γ-六氯环己烷>δ-六氯环己烷>β-六氯环己烷>α-六氯环己烷。灌域东北部和西南部残留浓度较高，并由这2个方向向中部地区逐渐递减，表层土壤中的六氯环己烷分布受土壤黏粒量、不同种植种类和灌溉水源的影响较大。虽受人类耕作的影响，但表层土壤中的六氯环己烷污染水平相对较低。     

基于网格空间数据的晋陕蒙接壤区生态环境综合评价

晋陕蒙接壤区是典型的生态过渡带、生态脆弱带。文章在调查研究的基础上 ,选取了 1 3个评价指标 ,应用层次分析法确定其权重 ,并将各个因子分级标准化和定量赋值 ,再用加权求和法得到每个评价单元的环境质量综合评价指数。根据环境综合评价指数将环境质量分为较好 (≥ 8)、一般 (≥ 6～ <8)、较差 (≥ 4～ <6)、恶劣 (<4) 4级。结果表明 :晋陕蒙接壤区的环境质量大多处于较差等级 ,较好、一般、较差、恶劣等级的面积比例分别为 2 .2 % ,2 8% ,5 7.4%和1 2 .4%     

苏南地区农村河塘底泥中重金属污染调查与评价

对苏南地区农村河塘底泥中重金属的污染物状况及分布特征进行了调查,分别在镇江、宜兴和常州采集了农村居民生活区、农田附近和养殖厂周围13个底泥样品,对底泥中的5种重金属Zn、Cu、Cd、Pb、Cr质量比进行了分析研究,并利用Hakason生态风险指数法评价了底泥中5种重金属对其所在水域的污染程度,对水域和周围环境造成的潜在风险影响.结果表明,苏南地区部分农村河塘底泥已受到轻度的重金属污染,部分采样点Cd、Cu和Zn已达到中度污染;不同类型底泥的重金属的污染程度趋势为:居民生活区＞养殖厂周围＞农田附近.     

钻井废泥浆中重金属化学形态及潜在生态效应评价

利用化学萃取法对江苏9个油田的不同类型钻井废泥浆的重金属化学形态分布特征进行调查分析,同时选用Hakanson的潜在生态危害指数法对钻井废泥浆中的重金属总量进行生态效应评价。结果表明,钻井废泥浆中Cu、Pb、Zn、Cd、Cr主要以残渣态和有机结合态为主,活性形态含量较低;采用Hakanson的潜在生态危害指数进行评价,发现Cu、Pb、Zn、Cd都属于轻微生态危害水平,而Cr多属于中等水平,产生潜在生态危害的重金属主要为Cr。     

Heavy metals in water bodies purified by suspended substrate of rivers

ＩｎｔｒｏｄｕｃｔｉｏｎＨｅａｖｙｍｅｔａｌｓｉｎｗａｔｅｒｂｏｄｉｅｓａｒｅｓｉｇｎｉｆｉｃａｎｔｌｙｄｉｆｆｅｒｅｎｔｆｒｏｍｏｒｇａｎｉｃｐｏｌｌｕｔａｎｔｓｔｈａｔｃａｎｂｅｍｉｃｒｏｂｉｏｌｏｇｉｃａｌｌｙｄｅｇｒａｄｅｄｏｒｄｅｃｏｍｐｏｓｅｄ .Ｇｅｎｅｒａｌｌｙ ,ｔｈｅｙａｒｅｐｕｒｉｆｉｅｄｔｈｒｏｕｇｈｔｈｅｉｒａｄｓｏｒｐｔｉｏｎｏｎｔｏｓｕｓｐｅｎｄｅｄｓｕｂｓｔｒａｔｅｓｉｎｒｉｖｅｒｓ.Ａｄｓｏｒｐｔｉｏｎｏｆｈｅａｖｙｍｅｔａｌｓｏｎｒｉｖｅｒｓｕｓｐｅｎｄｅｄｓｕｂ…     

铜陵石炭纪威宁期沉积相及与黄铁矿矿床的关系

铜陵地区石炭纪威宁期存在潮坪相,泻湖相和浅海陆棚相。白云岩有两种,准同生白云岩分布于潮坪,成岩白云岩分布于泻湖内,本区以成岩白云岩为主。白云岩中赋存了层位稳定的黄铁矿矿床,黄铁矿在泻湖相最易富集,成岩作用是黄铁矿矿床形成的一个重要因素。     

膨润土吸附－絮凝法处理污水中的重金属离子

研究了天然膨润土对Ｐｂ￣（２＋）、Ｃｄ￣（２＋）、Ｃｒ￣（３＋）的吸附和膨润土的絮凝沉降条件，将吸附与絮凝过程结合起来形成处理污水的新工艺，加入０．０４％膨润土和０．００６％的ＰＡＣ可使低浓度污水中Ｐｂ￣（２＋）脱除９３．１％。     

大顶子山航电枢纽工程建库后上游水质总量控制研究

松花江大顶子山枢纽工程建设后,库区内水体流线及扩散规律的变化将影响库区内水质,受沿江排污影响,其规划目标的水环境容量将发生改变,因此对建库后上游水质总量控制进行研究很有意义.     

Mechanics Principle and Engineering Application of Split Layer and Bed Separation of Mining Overburden

<正>To control land surface subsidence caused the underground mineral exploitation and the catastrophic phenomena such as serious damage of buildings, waterbodies, cultivated lands, railways, bridges caused by land subsidence, bed separation grouting technology of overburden is put forward. To provide theoretical support for the technology, the characteristics and the mechanics mechanism of mining overburden from layer-split to formation of bed separation are studied. On the basis of elastic sheet board theory, calculation formula of rock sheet deflection is presented, and the mechanics criteria of the separation formation and the calculation formula of bed separation volume are set up. Finally, the applications and technics of bed separation grout technology of mining overburden to control land subsidence in china are introduced.