核素迁移柱法实验和模拟计算

提出了一种计算土柱实验中核素迁移参数的方法,并采用脉冲源法测定了核素在土柱中的水流速度、弥散系数,使用计算软件对核素的流出曲线进行了数值模拟,并对影响核素流出时间的参数进行了灵敏度分析.结果表明,在本实验条件下,CXTFIT程序能对实验值给出很好的拟合,含有化学平衡吸附的对流-弥散模型可较好地模拟核素在土柱中的运移特性,水流速度对核素的流出时间影响最大.     

垃圾渗滤液中污染物在包气带运移模拟实验及预测

为揭示垃圾渗滤液中污染物在包气带中的迁移转化规律,通过静态吸附、静态降解、动态土柱和数学模型预测等方法进行模拟实验。结果表明,包气带对污染物的吸附过程是线性的,即S=KdC,吸附系数Kd=0.0976;降解曲线符合一级动力学方程,即C=C0e-λt,降解系数λ=0.0324d-1;弥散过程符合对流-弥散迁移转化模型,弥散系数D=0.00435m2·d-1,由此确定了污染物迁移数学模型。通过动态土柱实验验证了模型的可靠性,并利用模型对垃圾渗滤液中有机污染物(COD)的时空分布进行预测。     

多孔介质中三氯乙烯的非线性吸附-对流-弥散模型

研究三氯乙烯(TCE)在含水层中的迁移转化规律,对评价其在环境中的影响、预测其在环境中的行为规律及确定相应的修复技术有着重要的意义.TCE在细砂中的等温吸附规律研究采用批试验和模拟柱试验方法.批试验结果采用四种不同的非线性等温吸附模型进行拟合.结果显示,Linear-Langmuir-Freundlich (LLF) 模型的拟合效果最佳,且该模型能较好地描述表面吸附和分配作用.利用经典对流扩散模型,将以KCl为示踪剂的柱试验结果采用非线性最小二乘法反演模拟柱中的纵向弥散度;利用非线性吸附对流扩散模型,将TCE的模拟柱试验结果采用遗传算法反演吸附参数;结果显示Langmuir等温吸附模型描述柱试验中的吸附模式最好.即批试验与柱实验中的吸附模式是不同的.该结论表明必须重新审视非平衡吸附理论在运移模型中的适用性,以及该理论适用的前提条件.在试验结果和模型反演获得的参数基础上确定的TCE在多孔介质中运移的一维非线性吸附-对流-扩散模型,能够很好地揭示TCE在多孔介质中的运移规律,且模型中的阻滞系数是质量浓度的非线性函数.     

模拟酸雨对土柱中稀土元素迁移的影响

模拟研究酸雨对土柱中稀土元素迁移的影响.结果表明,在雨水、酸雨淋溶下,对照组红壤土柱中所含稀土元素有向下迁移的趋势,并且随淋溶液pH值的降低,稀土元素向下迁移的能力增加.外源稀土迁移量的大小顺序为;Ce>La>Nd>Pr,其顺序与各稀土元素在稀土微肥中含量大小的顺序相同.表明外源稀土的迁移性与外源稀土的总量密切相关.外源稀土在土柱中的含量随着红壤深度的增加而减少,稀土元素主要在土柱中第一、二层持留;随着淋溶液酸度的下降,稀土元素向下迁移的能力增加.     

气相抽提去除红壤中挥发性有机污染物的去污机理探讨

通过探讨土壤气相抽提去除红壤中挥发性有机污染物的去污机理,建立了一维稳态条件下污染物在土壤多孔介质中传质的总微分方程,分别求出了平衡模型和动力学模型的解析解和数值解,并用实验结果对平衡模型和动力学模型进行了模拟和验证.实验结果和模型模拟结果表明理论模型与实验结果吻合良好,平衡模型和动力学模型在描述污染物在土柱通风过程中的传质时,分别适用于不同的阶段.在通风初期平衡模型能够很好地描述实验结果,而随着时间的推移,平衡模型的预测曲线逐渐偏离数据点,到了通风中后期,只有动力学模型才能够较好地描述和预测实验结果.     

干旱区绿洲灌漠土Cu、Zn和Pb的吸附解吸特征

土壤重金属吸附解吸是影响土壤系统中重金属移动性和归宿的主要过程,影响重金属的生物有效性以及重金属在食物链中的传递等.配制一系列不同浓度的重金属,灌漠土对重金属溶液进行吸附实验24 h以达到平衡,再用硝酸铵和乙酸铵进行解吸实验24 h以达到平衡.利用热力学吸附平衡法,对西北干旱区绿洲灌漠土重金属Cu、Ni和Pb的吸附解吸行为进行序批实验研究.实验结果表明:(1)灰漠土在常温下对铜、锌和铅重金属离子的吸附等温线符合Freundlich型吸附模式,灰漠土对重金属铜、锌和铅的吸附能力由强到弱的顺序为:铅,铜,锌.(2)硝酸铵和乙酸铵解吸重金属的量与灰漠土吸附重金属量呈现出线性正相关,乙酸铵解吸重金属的量比硝酸铵解吸重金属的量大,两种解吸剂对铜、锌和铅重金属离子的解吸能力由大到小的顺序都为:铜,锌,铅,说明了一般外源的铜、锌和铅进入土壤以后,铜和锌可能比铅容易向四周转移.(3)硝酸铵和乙酸铵的解吸率呈谷形曲线,开始时硝酸铵和乙酸铵解吸重金属量的百分比随灰漠土吸附重金属量的增加而减小,在吸附量达到某一特定值时,解吸率随吸附量的增加而增加.灰漠土对铜、锌和铅的吸附作用以专性吸附为主,被灰漠土吸附的铜、锌和铅重金属离子较难解吸.     

5-Br-PADN分光光度法连续测定废水及人发中的铜和锌

用PAN连续测定铜和锌已有报导。由本实验室合成的新显色剂1-[(5-溴-2-吡啶)偶氮]-2,7-萘二酚(简称5-Br-PADN),与PAN比较,该试剂在吡啶环上引入一个溴原子,在萘环上引入一个羟基。由于助色效应,灵敏度有所提高。 关于5-Br-PADN与铜、锌的单独显色反应,杨桂法等已作过研究。在此基础上,我     

土壤重金属复合污染对作物的影响

本文采用盆栽试验，研究了石灰性土壤中铜、镍、铅、锌复合污染对大豆和水稻的影响，并讨论了离子冲量在表征复合污染的综合效应及污染金属总量控制中的应用。结果表明：对于水稻，共存元素协同使产量降低，它们的影响顺序是：铜＞锌＞镍＞铅；对于大豆，铜、铅、锌的存在降低了镍的毒性，影响顺序了：铜＞铅＞锌＞镍。供试元素在作物体内的累积、分布和迁移除了受到本身性质和添加量影响外，还受到元素相互作用的影响，后者的影响很     

地下水中铵态氮的迁移转化过程

铵态氮进入地下水的主要途径是土壤淋失,通过室内土柱淋滤实验研究铵态氮在土壤中的迁移转化过程,测定不同时间和不同深度土壤中铵态氮及其转化物硝态氮和亚硝态氮的浓度变化,分析了影响铵态氮迁移转化的因素。实验表明：在土壤饱和、持续淋滤条件下,土柱中随采样深度的增加,铵态氮穿透时间延长,依次滞后;通过硝化能力分析,土柱上层发生了轻微的硝化反应,土柱底部发生了反硝化反应,导致硝态氮的浓度衰减。研究认为在铵态氮的迁移转化过程中,当入渗铵态氮浓度较低时,影响铵态氮迁移转化的显著因素是土壤对铵态氮的吸附;当入渗铵态氮浓度较大时,影响铵态氮迁移转化的显著因素是生物作用导致的铵态氮的硝化,以及土壤的渗透系数、弥散度等因素。     

环境介质中有机污染物运移的数值模型

在综合考虑有机污染物在土壤-水环境体系中扩散、吸附解吸、分配以及土壤-水界面微生物降解条件下，建立了环境介质中有机污染物迁移转化的非平衡动力学模型，并编制相应的有限元程序，利用该程序对落地原油在土壤中迁移转化非平衡模式与平衡模式进行对比模拟分析，探讨了模型参数kd、λ、λ^*的变化对有机污染物迁移的影响，为定量研究土壤中有机污染物在土壤-水环境中分配与归宿提供了可靠的理论依据，同时为土壤环境质量评价及污染预测、预报与污染防治提供科学的根据与途径．图4表1参11     

Zn,Cu和Ni污染土壤中重金属的化学固定

利用化学固定剂处理被污泥中Zn,Cu和Ni污染的土壤,研究不同化学药剂对重金属离子的固定技术.结果表明,石灰、硫化物和硅酸盐对Zn都有较好的稳定效果,硫化物对Cu的稳定效果较好,硅酸盐和石灰对Ni的稳定效果较好;对于被Zn,Cu和Ni污染的土壤,混合药剂对重金属污染物的固定效果最佳.研究表明通过调解系统的pH和生成稳定化合物形态使土壤中Zn,Cu和Ni得以固定.通过硫化物 石灰化学固定处理,固定前后Zn,Cu和Ni的不稳定形态含量分别减少了69%,56%和59%.     

Pollution distribution of heavy metals in surface soil at an informal electronic-waste recycling site

We studied distribution of heavy metals [lead (Pb), copper (Cu) and zinc (Zn)] in surface soil at an electronic-waste (e-waste) recycling workshop near Metro Manila in the Philippines to evaluate the pollution size (spot size, small area or the entire workshop), as well as to assess heavy metal transport into the surrounding soil environment. On-site length-of-stride-scale (~70 cm) measurements were performed at each surface soil point using field-portable X-ray fluorescence (FP-XRF). The surface soil at the e-waste recycling workshop was polluted with Cu, Zn and Pb, which were distributed discretely in surface soil. The site was divided into five areas based on the distance from an entrance gate (y-axis) of the e-waste recycling workshop. The three heavy metals showed similar concentration gradients in the y-axis direction. Zn, Pb and Cu concentrations were estimated to decrease to half of their maximum concentrations at ~3, 7 and 7 m from the pollution spot, respectively, inside the informal e-waste recycling workshop. Distance from an entrance may play an important role in heavy metal transport at the soil surface. Using on-site FP-XRF, we evaluated the metal ratio to characterise pollution features of the solid surface. Variability analysis of heavy metals revealed vanishing surficial autocorrelation over metre ranges. Also, the possibility of concentration prediction at unmeasured points using geostatistical kriging was evaluated, and heavy metals had a relative “small” pollution scales and remained inside the original workshop compared with toxic organohalogen compounds. Thus, exposure to heavy metals may directly influence the health of e-waste workers at the original site rather than the surrounding habitat and environmental media.     

蚯蚓对垃圾与底泥中镉的富集现象

通过蚯蚓处理垃圾及纳污河流底泥实验研究发现蚯蚓可选择吸收并富集垃圾及底泥中的镉，但对其他重金属元素铅、铜、锌等并无此种富集吸收现象。     

Biokinetic modeling of heavy metals in earthworms

Studies concerning bioaccumulation kinetics and bioconcentration factor (BCF) of heavy metals like zinc (Zn), lead (Pb), chromium (Cr), cadmium (Cd), and copper (Cu) in earthworm Eudrilus eugeniae tissues including integument, gizzard, clitellum, and head region were undertaken. Calculated BCF, predicted K _ow, and predicted K _oc showed a significant correlation between heavy metals in different earthworm tissues, in substrate spiked with heavy metals. The regression coefficient (r ²) between heavy metal uptake concentration and exposure time varied between 0.73 and 0.99, indicating significant correlation. The K _oc was a maximum of 13.9016 in case of Cu and integument at an exposure time of 100 days and a minimum of 0.1114 in case of Cr with respect to head at the same exposure time. Earthworms accumulated heavy metals following chronic exposure to municipal solid waste containing heavy metals. BCF and uptake rate kinetics of heavy metals were calculated and showed increased values in head tissue followed by integument.     

Heavy metals from soil and domestic sewage sludge and their transfer to Sorghum plants

We studied the mobility and transport of heavy metals such as Cu, Zn, As, Cd, Cr, Ni, and Pb, from soil and soil amended with sewage sludge to sorghum plants. The total and ethylenediaminetetraacetic acid (EDTA) extractable heavy metals in agricultural soil and untreated domestic sewage sludge (DWS) samples were determined. The correlation between the total and extractable metals in soil and sewage sludge was investigated. The total and extractable heavy metals in soil, sewage sludge and sorghum grain were analysed by flame and electro thermal atomic absorption spectrometer (FAAS/ETAAS), after digestion in microwave oven. Statistically good correlations were obtained between the total contents of all heavy metals and their respective extractable fractions in soil and domestic wastewater sludge. Transfer factors of all heavy metals from domestic sewage sludge to sorghum grains were determined.     

我国典型土壤上重金属污染对番茄根伸长的抑制毒性效应

采用盆栽试验观测了我国3种典型土壤——黄泥土、褐土、红壤上不同重金属(铜、锌、铅)作用下敏感植物番茄的根伸长,其中黄泥土和褐土上重金属添加量范围为Cu(0～2000mg·kg-1)、Zn(0～4000mg·kg-1)和Pb(0～5000mg·kg-1),红壤上为Cu(0～400mg·kg-1)、Zn(0～750mg·kg-1)和Pb(0～2000mg·kg-1).对不同土壤上Cu、Zn、Pb对番茄的根伸长抑制率进行了比较,以阐明不同土壤上重金属种类及用量对蔬菜根生长的抑制及毒性效应.结果表明,相同Cu、Zn、Pb污染水平(添加量)下,土壤中重金属对番茄的根伸长抑制率大小顺序基本表现为:红壤>黄泥土>褐土.番茄对红壤中的重金属最敏感,其次是黄泥土,再次是褐土.番茄对不同重金属的毒性响应不同,对Cu最敏感,Zn和Pb次之.土壤中有效态重金属含量与番茄根伸长呈显著(p<0.05)或极显著(p<0.01)负相关,表明有效态重金属含量是影响蔬菜根伸长的重要因素.     

徐州市城区公园绿地土壤重金属污染及其评价

通过对徐州市泉山、云龙、鼓楼、九里4个城区的公园绿地土壤进行系统采样测定,对其土壤重金属富集与污染状况进行分析与评价。结果表明,该城区表层土壤中5种重金属(Cd、Cu、Zn、Pb、Cr)含量均高于中国土壤元素背景值,其中Cd单因子富集指数为30.00,污染指数为14.56,富集程度较高,污染较严重;Cu、Zn、Pb、Cr单因子富集指数和污染指数均接近1,富集程度较低,无污染或轻度污染。     

湘南某矿区菜园土中典型重金属的形态分析

分别运用Tessier连续提取法和Leleyter连续提取法研究湘南某矿区菜园土中Pb,Zn,Cu和Cd的形态分布特征.结果表明：菜园土中Pb,Zn,Cu和Cd的总浓度严重超过国家土壤环境质量标准.Pb,Zn,Cu和Cd的主要形态是残渣态,水溶态和交换态所占比例较小.重金属生物可利用性的研究表明,Pb,Zn,Cu和Cd生物可利用的含量较少;在Tessier方法中,除Cu之外,生物不可利用态是主要形态,其次是潜在生物可利用态,而在Leleyter方法中,潜在生物可利用态是主要形态,其次是生物不可利用态.     

Accumulation of heavy metals in soil and paddy crop (Oryza sativa), irrigated with water of Ramgarh Lake,Gorakhpur, UP,India

Heavy metals, a highly polluting group of constituents known to exert adverse effects, tend to accumulate in living organisms. The objective of this study was to determine the accumulation and translocation of heavy metals in soil and in paddy crop irrigated with lake water compared to soil and paddy crop irrigated with bore-well water. The quantities of heavy metals (Cd, Cr, Cu, Pb, Zn, As, Mn, and Hg) were determined in different parts of rice plants (Oryza sativa). Results revealed that the mean levels of soil Cd, Cr, Pb, Zn, As, Mn, and Hg in experimental soil and in different parts of rice plant (root, straw, and grain) were higher than the control except for Cu. The content of eight toxic metals was significantly higher in root than in aerial parts of the rice (straw and grains). Rice roots were enriched in Cd, As, Hg, and Pb from the soil, while Cr, Cu, Zn, and Mn were hardly taken by the roots. Bioaccumulation factor for Hg was significantly higher than other heavy metals. Metal transfer factors from soil to rice plants were significant for Cd, Cr, Cu, Pb, Zn, As, Mn, and Hg. The concentrations of metals in lake water were found to be within the permissible limit of Indian standard prescribed by Central Pollution Control Board (2000), except for Hg and As, which were higher than the limit of Indian standard. However, the concentrations of heavy metals in soil and rice grains were still below the maximal levels, as stipulated by Indian Prevention of Food Adulteration Act (PFA, 1954) and World Health Organization (WHO, 1993) guidelines.     

宝鸡城市街尘、土壤及河流沉积物重金属形态迁移特征

在宝鸡城市街尘、土壤及河流沉积物基本理化性质和重金属元素含量分析的基础上,重点研究了重金属元素在街尘、土壤及河流沉积物中的赋存形态和迁移特征.结果表明:在街尘中Cu主要以可氧化态和残余态形式存在,Pb主要以可还原态和可氧化态形式存在,Zn和Cd主要以乙酸可提取态形式存在,Mn、Fe、Co、Ni和Cr主要以残余态形式存在...