重金属在土壤-水稻系统中的迁移转化规律研究

重金属在土壤-水稻系统中的迁移转化,受其在水稻土中的形态分布、土壤理化性质、有机物料和微量或大量元素的交互作用影响,以及其在水稻根际环境中的形态转化条件制约.重金属在水稻植株中的分布、迁移和总量传输,是一个动态过程.不同重金属处理水平、不同生长期水稻的不同器官的重金属含量不一,从土壤和根部传输上来的重金属会逐渐积累.     

重金属随泥沙迁移过程的数学模型

为更加准确地模拟重金属随泥沙迁移的过程,避免传统模型在描述重金属的吸附解吸时只能片面地考虑简单物理过程的不足,在水沙输移模拟的基础上,同时考虑了重金属随泥沙迁移的物理和化学过程,建立了完整的水动力-泥沙-重金属迁移数学模型。模型利用泥沙颗粒表面复杂形貌与电荷的关系来修正表面络合模型并以此分析了水体中的重金属与泥沙颗粒表面基团间的化学成键作用,同时根据化学反应的不同条件,并结合床面冲淤,将床面泥沙分为有氧层和无氧层分别考虑重金属的沉积与再释放。模型模拟了水槽试验中重金属Ni随泥沙迁移的情况,计算结果与实测数据的对比表明了建立的模型可以合理地反映重金属随泥沙的迁移过程。     

重金属随泥沙迁移过程的数学模型

为更加准确地模拟重金属随泥沙迁移的过程,避免传统模型在描述重金属的吸附解吸时只能片面地考虑简单物理过程的不足,在水沙输移模拟的基础上,同时考虑了重金属随泥沙迁移的物理和化学过程,建立了完整的水动力-泥沙-重金属迁移数学模型。模型利用泥沙颗粒表面复杂形貌与电荷的关系来修正表面络合模型并以此分析了水体中的重金属与泥沙颗粒表面基团间的化学成键作用,同时根据化学反应的不同条件,并结合床面冲淤,将床面泥沙分为有氧层和无氧层分别考虑重金属的沉积与再释放。模型模拟了水槽试验中重金属Ni随泥沙迁移的情况,计算结果与实测数据的对比表明了建立的模型可以合理地反映重金属随泥沙的迁移过程。     

水环境污染物迁移转化研究与泥沙运动

从三个方面,即泥沙颗粒本身的性质,污染水体中泥沙运动特点如污水氧化塘中的泥沙运动、河口段的泥沙运动,天然水体中污染物如重金属、难降解有机污染物、营养性污染物和油污染物迁移转化、归宿现象,阐述了将环境科学主要是水环境化学、环境地球化学、水化学和水利工程科学主要是水力学、泥沙运动力学结合起来研究水环境问题的重要性和必要性。     

非饱和土壤溶质迁移转化模型参数优化估算

在分析非饱和土壤中水分和溶质迁移转化规律的基础上,采用与坐标网格相适应的分块连续作用的水动力函数,研究模型参数最优化估算技术.运用Gauss-Newton最小化计算的Levenberg-Marquardt修正法来实现反求模型的迭代问题.该方法被应用于估算一维土柱和二维土槽试验研究模型的参数,探讨了参数给定与估算数量对参数的置信区间和预测效果的影响.经验证表明,参数优化估算技术是可行的,以此参数进行模型预测,其结果是可信的.     

泥沙吸附重金属污染物室内静态试验研究

从吸附反应动力学方程和质量守恒方程出发,导得室内静态试验中泥沙吸附量和水相重金属浓度随时间变化的计算公式,并得出泥沙平衡吸附量和水相平衡浓度随泥沙吸附特性、水相重金属离子初始浓度和泥沙浓度变化的计算公式。结合室内试验,认为泥沙浓度不影响吸附特性参数,如饱和吸附量b、吸附-解吸速率常数k及吸附速率系数k1.     

水库三维Fe、Mn迁移模型——阿哈水库实例研究

通过描述Fe、Mn在水库中的氧化还原变化、吸附、解吸、沉降及再悬浮,考虑水流运动对Fe、Mn迁移变化的影响,研制了水库三维水动力模式及三维Fe、Mn迁移变化模式,从而建立了完整的水库三维Fe、Mn迁移分布模拟模型。该模型在阿哈水库实际运用效果良好。模拟结果表明,水库水流运动整体流速较小,Fe、Mn在水库中平行迁移运动缓慢。进入水库的Fe、Mn负荷大量沉入库底,在水体缺氧条件下,底质中Fe、Mn重新释放,形成明显的Fe、Mn分布垂直梯度,造成水库下层Fe、Mn大大超过国家生活饮用水质量标准。     

阿特拉津在地下水中迁移转化的实验研究

阿特拉津是研究区内广泛使用的旱田除草剂。为治理其污染的地下水 ,采用静态和动态实验的方法研究其在含水介质砂层中的吸附特性和在地下水中的迁移转化规律。实验结果表明 :砂层对阿特拉津的吸附量小 ,不同固液比 (1.0、0 .5、0 .2 )时的分配系数分别为 0 .10 ,0 .15 ,0 .19cm3 /g ;含水层的弥散度为 0 .0 336m ,阻滞因子为 1.2 9,自然净化系数为 0 .0 0 2 8/d。由此确定所建立的数学模型和参数 ,为研究区阿特拉津污染地下水的治理提供可靠的依据     

硝基苯在含水层中的迁移规律及其转化机理研究

本文通过室内模拟实验，探讨在河流入渗补给地下水的条件下．硝基苯在含水层中的迁移规律及其转化机理。迁移规律实验结果表明，从进水口至出水口的各取样点依次出现硝基苯浓度峰值．并且随着硝基苯迁移路径的延长其浓度峰值相应变小。硝基苯的浓度峰值在含水介质中的持续时间并不很长，但由于硝基苯解吸附作用的存在。在此后相当长的一段时间里都存在较为明显的拖尾现象。转化机理实验结果表明，吸附与生物降解作用是影响硝基苯在含水层中迁移转化的主要因素。淤泥介质对硝基苯的吸附能力要明显大于砂砾介质，淤泥介质中的微生物对硝基苯的吸附影响较大．而砂砾介质中的微生物对硝基苯的吸附影响较小。     

黄河中游对硝基氯苯传输迁移转化模拟

进行了对硝基氯苯在黄河中游天然河道中的输送、迁移和转化的水质模拟研究。重点研究了大量泥沙对对硝基氯苯运动和归宿的影响及水质模型的率定和检验方法。模拟了在点源输入下,不同水情期,泥沙不同冲、淤格局的对硝基氯苯的输移。该水质模型由三个子模型构成,除了描述水流运动的水动力学模型外,还有描述河中可溶性有机碳沿程变化和对硝基氯苯在泥沙中的分配及其光解、挥发作用的子模型。     

重金属离子在胡敏酸-高岭石复合体上的吸附

本文研究了胡敏酸存在下高岭石对重金属离子的吸附行为。实验结果表明:①胡敏酸和Cu2 溶液按先后顺序或同时加入高岭石中反应,在Cu2 平衡浓度<10mg/L时,3种加入顺序对Cu2 的吸附量基本相同,当Cu2 平衡浓度>10mg/L时,(K Cu) HA和(K Cu HA)两种加入顺序对Cu2 的吸附量比(K HA) Cu的略大。②在pH=5时,胡敏酸-高岭石复合体对Cu2 的吸附量明显大于纯高岭石。这是由于胡敏酸含有大量的羧基和酚羟基等活性基团,吸附在高岭石上的胡敏酸增加了其表面吸附位,在复合体表面形成了S—HA—Cu三元配合物,且Cu2 的吸附量与复合体中胡敏酸的含量在一定范围内成正相关;③溶液pH值在4～7之间变化可调控复合体对Cu2 的吸附机制。④在Cu2 和Cd2 共存时,随着金属离子初始浓度的增大,Cu2 的吸附量呈直线上升,而Cd2 的吸附量增加缓慢,表明复合体对Cu2 的吸附能力比对Cd2 强。     

Human Influence on Heavy Metal Distribution in the Upper Lake Nansi Sediments, Shandong Province, China

Core and surface sediment samples were collected from three sub-lakes ( Lake Nanyang, Lake Dushan and Lake Zhaoyang) in the Lake Nansi Basin, Shandong Province. In order to reveal the characteristics of spatial and historical distribution of heavy metals in different sublakes of the Upper Lake Nansi, heavy metal (As, Cr, Cu, Hg, K, Mn, Ni, Pb, Zn, Al, Fe, Ti and V) concentrations of sediment samples were investigated. Based on the activity of^137Cs in the sediments, the modem accumulation rate of Lake Nansi sediments is 3.5 mm/a. Our results show that the whole Upper Lake Nansi has been already polluted by heavy metals, among which Lake Nanyang has been polluted seriously by mercury, as well as by lead and arsenic, while Lake Dushan has been most seriously polluted by lead and arsenic. Historical variation of heavy metal (Cr, Cu, K, Ni, Zn, A1, Fe, Ti and V) concentrations shows an abrupt shift in 1962, resuiting in a division of two periods: from 1957 to 1962 when metal enrichment increased with time, and from 1962 to 2000 when it decreased with time, while that of some anthropogenic elements such as Hg, Pb and Mn tend to increase toward the surface. However, the variation trend of As in the sediments is different from that of Hg, Pb and Mn, with its maximum value appearing in 1982. Since 1982 the concentrations of As have decreased due to the forbidden use of arsenite pesticides. This variation trend revealed changes in manner of human activity (coal combustion, waste discharges from both industries and urban sewage ) within the catchment during different periods.     

Study on the mechanism of transport of heavy metals in soil in western suburb of Beijing

1 IntroductionIncorporation of potentially toxic metals ( e.g.Cd, Cu, Cr, Pb, Hg, As, Se, Zn, Ni) into soils ei-ther through sewage-sludge irrigation or some othersources of pollution (e.g. atmospheric deposition, ap-plication of agri-chemicals) has posed…     

Microbial resistance to the heavy metal pollution

It is estimated that the poisonous heavy metals released to the environment come up to million tons. Such great amounts of poisonous heavy metals result in a serious bane to ecosystem and human health. The valid control of spreading and pollution of heavy metals in the environment has hence become an urgent issue of the moment. In this study, through tameness and induction of living creature＇s tolerance from dirty mud, using microbial technology we have cultivated some anti-heavy-metal microbes able to resist the pollutions from poisonous chemical elements such as arsenic, chromium, cadmium, hydrargyrum, and plumbnm, four of which are fungi and five are bacteria. Atomic absorption spectroscopy and atomic fluorescence spectrophotometry analyses showed that, to the same chemical element, fungi have stronger resistance than bacteria by one time or so.     

Experimental Study on Surface Reactions of Heavy Metal Ions With Quartz—Aqueous Ion Concentration Dependence

Adsorption of divalent metal ions, including Cu²⁺, Pb²⁺, Zn²⁺, Cd²⁺ and Ni²⁺, on quartz surface was measured as a function of metal ion concentration at 30°C under conditions of solution pH= 6. 5 and ion strength I = 0. 1mol/L. Results of the experimental measurements can be described very well by adsorption isotherm equations of Freudlich. The correlation coefficients (r) of adsorption isotherm lines are > 0. 96. Moreover, the experimental data were interpreted on the basis of surface complexation model. The experimental results showed that the monodentate-coordinated metal ion surface complex species (SOM⁺) are predominant over the bidentate-coordinated metal ion surface complex species [(SO)₂M] formed only by the ions Cu²⁺, Zn²⁺ and Ni²⁺. And the relevant apparent surface complexation constants are lgK_M = 2.2–3.3 in order of K_Cd≥K_Pb > K_Zn > K_Ni≥K_Cu, and lgβ_M = 5.9-6.8 in order of β_Ni > β_Zn > β_Cu. Therefore, the reactive ability of the ions onto mineral surface of quartz follows the order of Cd > Pb > Zn > Ni> Cu under the above-mentioned solution conditions. The apparent surface complexation constants, influenced by the surface potential, surface species and hydrolysis of metal ions, depend mainly on the Born solvation coefficient of the metal ions. This project was financially supported by the National Natural Science Foundation of China (No. 49572091).     

Combining forms of heavy metal elements in Dianshan Lake sediments and their spatial and temporal variations

Dianshan Lake is one of the important water supply sources for Shanghai City. The contents of heavy metals in the sediments are obviously higher than those in the overlying water body. The contents of Pb in the sediments vary seasonally; with increasing depth, the contents of Cd, Pb, Cu, Cr and Fe show no variation generally, but Mn varies in the peak pattern. Cd, Pb, Cu, Cr and Fe in the sediments are present predominantly in sludge phase, but iron and manganese oxide form of Pb and organic matter-sulfide form of Cu are their respective preferential combining forms. Manganese is present largely in exchangeable form, iron-manganese oxide combined form and sludge form. The contents of the various forms of Cd, Pb, Cu, Cr and Fe tend to vary with changing season and depth. The contents of exchangeable forms of Fe and Mn vary with depth in the peak-like pattern.     

江苏典型地区河流沉积物重金属元素分布特征及其污染来源

通过对河流沉积物等地表沉积物中重金属元素分布等环境地球化学调查数据的统计分析,总结了江苏典型地区河流沉积物中重金属元素的分布特点与规律:江苏局部地区河流沉积物中,Cd、Pb、Zn、Cr、Cu、Ni、Hg等相对富集趋势明显,Cd最大富集倍数 100;不同河流沉积物的重金属元素分布存在差异,与其污染来源密切相关;工业排放是导致河流重金属污染的主要原因,使用含Cd的颜料作为调色剂导致部分河流出现严重Cd污染;与土壤等其他地表沉积物相比,河流沉积物中重金属元素的分布更不均衡。查明河流沉积物的重金属元素分布可为相关农产品安全性预测、确定重金属污染来源、追踪涉重产业的发展历程、防治局部耕地重金属污染等提供科学依据。     

黏土固化注浆帷幕控制重金属污染物运移的数值模拟

针对南昌市麦园垃圾卫生填埋场渗滤液防渗的实际情况,分析了重金属污染物在黏土固化注浆帷幕中的迁移转化特征,建立了地下水渗流模型和重金属污染物运移的耦合动力学模型。利用该模型对黏土固化注浆帷幕控制重金属污染物的迁移行为进行了模拟研究。数值模拟结果表明,在填埋场设计使用年限内黏土固化注浆帷幕对重金属污染物的阻滞率可以达到94.5 %以上,重金属污染物在防渗系统中的浓度范围沿地下水水流方向逐渐扩展,同一位置的浓度值随时间的延续呈逐渐增大的趋势,但距离污染源越远,污染物的浓度越低。结合现场检测情况,证明了黏土固化注浆帷幕对重金属污染物具有较强的污染控制能力。     

Heavy metal contamination in the sediment of the Second Songhua River

The Second Songhua River was subjected to a large amount of untreated effluent from petrochemical industries in Jilin City in the 1960s to the 1970s. The objectives of this study were to investigate the mercury and other heavy metal contamination in the sediment of the river. The river bottom sediment was sampled from the river segment between Jilin City to Haerbin City in 2005. Total concentrations of Hg, Cd, Cu, Cr, Pb, Zn, Ni, As, Sc, and major cations （A1, Fe, Mg, Ca, K, Na） in the sediment were measured by atomic fluorescence spectrometer, ICP-MS, and ICP-OES, respectively, following digestion with various acids. We found the concentrations of most elements in the uncontaminated sediment were significantly correlated to those of Sc.