Distribution of heavy metals in an incineration system of solid wastes in the Three-Gorges region of the Yangtze River

On the basis of investigations on the composition and contents of heavy metals in the domestic refuse in the Three-Gorges region of the Yangtze River, in combination with the experimental results, this paper deals with the distribution rule of heavy metals in the various compartments of an incineration system： leachate pool, fly ash and residue. It is concluded that in the leachate pool heavy metals should not be neglectable since about 30% of Pb and 10% of Cr are leached here; in the incineration system, above 74% of Cr, As and Pb exists in residue; above 96% of Hg exists in fly ash and the contents of Cd in fly ash are close to those of residue. It is also concluded that the physical conditions of incineration have a significant influence on the distribution of heavy metals in the incineration system.     

Using Multivariate Statistical and Geostatistical Methods to Identify Spatial Variability of Trace Elements in Agricultural Soils in Dongguan City,Guangdong,China

Dongguan (东莞) City, located in the Pearl River Delta, South China, is famous for its rapid industrialization in the past 30 years. A total of 90 topsoil samples have been collected from agricultural fields, including vegetable and orchard soils in the city, and eight heavy metals (As, Cu, Cd,Cr, Hg, Ni, Pb, and Zn) and other items (pH values and organic matter) have been analyzed, to evaluate the influence of anthropie activities on the environmental quality of agricultural soils and to identify the spatial distribution of trace elements and possible sources of trace elements. The elements Hg, Pb, and Cd have accumulated remarkably here, incomparison with the soil background content of elements in Guangdong (广东) Province. Pollution is more serious in the western plain and the central region, which are heavily distributed with industries and rivers. Multivariate and geostatistical methods have been applied to differentiate the influences of natural processes and human activities on the pollution of heavy metals in topsoils in the study area. The results of cluster analysis (CA) and factor analysis (FA) show that Ni, Cr, Cu, Zn, and As are grouped in factor F1,Pb in F2, and Cd and Hg in F3, respectively. The spatial pattern of the three factors may be well demonstrated by geostatistical analysis. It is shown that the first factor could be considered as a natural source controlled by parent rocks. The second factor could be referred to as "industrial and traffic pollution sources". The source of the third factor is mainly controlled by long-term anthropic activities ,ad a consequence of agricultural fossil fuel consumption and atmospheric deposition.     

Comparison of 24 h and Long-term pHstat Leaching Tests for Heavy Metal Mobilization from Solid Matrices

The dynamic leaching behaviour of environmentally relevant heavy metals makes it difficult to fix a suitable elution time of leaching tests. With ten different solid materials which were characterized by wavelength-dispersive X-ray fluorescence analysis and by the determination of aqua regia soluble amounts of heavy metals we performed 24 h and long-term leaching tests using the pH_stat procedure at pH 4 to be able to compare the resulting acid neutralization capacities (ANC) and heavy metal mobilization. This comparison demonstrates firstly the limitations in predicting the extent of heavy metal release after a longer (geological) time period only from the leached amounts after 24 hours and the ratio of the ANC values measured in the 24 h test and in a long-term experiment, respectively. Secondly, the effect of elution time on the leachability is not uniform but element specific and matrix dependent. Hence, the pH_stat leaching test performed in the usual manner does not seem to be suitable particularly for assessing long-term mobilization of heavy metals under acidic conditions. Additional experiments under variation of shaking frequency and time clearly demonstrate the dominant influence of the first parameter on the resulting ANC and support the necessity of further studies to optimize the pH_stat leaching procedure before the test can be recommended in regulations for environmental protection.     

Applicability of Single and Sequential Extractions for Assessing the Potential Mobility of Heavy Metals in Contaminated Soils

Heavy metal polluted sites are bearing an acute hazardous risk for the groundwater, but also a potential one. While the acute risk can be assessed directly via seepage water measurements, determination of the potential risk is much more complex. It results from the sum of all reactions that are capable to mobilize heavy metals under worst case environ-mental conditions. Using a fourfold sequential extraction (SE₄) such a worst case was simulated for four soils highly contaminated with Pb, Zn, and Cu. The resulting potential mobilizable amounts ϕ_pm have been compared with those derived from 6 single extractions. By means of variance analyses, it is shown that ϕ_pm of lead can be represented by a single extraction with NH₂OH. In contrary, ϕ_pm of zinc can be represented using the pH_stat test or an extraction with aqua regia, while ϕ_pm of copper can be represented only by aqua regia extraction. The water-soluble amounts deriving from the DEV-S4 test do not correlate with the potential mobilizable amounts of any metal. Therefore, an assessment of contaminated sites should include an aqua regia extraction additionally to the seepage water analysis.     

变质改造型关键金属矿——富集Li-Rb-Cs-Tl-Ga的云母片岩

关键金属矿产是国际上最近提出的资源概念,对战略性新兴产业的发展至关重要,但认知程度较低。洛扎岩浆-变质杂岩体位于喜马拉雅带东部,侵位于藏南拆离系内。在岩体东北侧,云母片岩被含电气石淡色花岗岩捕虏。云母片岩主要由金云母、绿泥石和少量黑云母组成。从全岩地球化学成分来看,云母片岩具有含量较高的Al₂O₃(13.38%～14.32%)、K₂O(6.09%～9.66%)、FeO^*(27.11%～30.09%)、MgO(15.25%～17.21%)、TiO₂(0.09%～0.26%),富集关键金属Li(650×10^-6～1 031×10^-6)、Rb(1 649×10^-6～2 773×10^-6)、Cs(98×10^-6～229×10^-6)、Tl(5.7×10^-6～12.1×10^-6)、Ga(121×10^-6     

钦州湾沉积物中重金属的多元统计分析：空间关系、生态风险和来源识别

海湾是海洋和陆地相互作用和人类活动最强烈的区域,沉积物中重金属的含量和分布都受到人类活动的影响。为了探究钦州湾沉积物中重金属的含量水平、污染程度和可能来源,本研究分析了钦州湾表层沉积物中Cu、Pb、Zn、Cd、Cr、Hg和As的含量及空间分布,采用地质累计指数（Igeo）和潜在生态风险指数（PERI）定量分析了重金属的污染程度和生态风险,并利用自组织映射(SOM)和正定矩阵因子分解法(PMF)模型评估了重金属的可能来源。结果表明：钦州湾表层沉积物重金属中Zn的平均含量最高,Hg平均含量最低;除个别站位的Pb含量符合海洋沉积物质量第二类标准外,其他重金属含量均符合海洋沉积物质量第一类标准;Igeo结果表明钦州湾表层沉积物主要的污染元素为Pb、Hg和Cu;PERI结果表明Hg是钦州湾表层沉积物主要的生态风险元素。SOM和PMF模型结果表明钦州湾表层沉积物重金属主要受自然来源、农业活动、工业生产活动的共同影响,各来源的相对贡献率分别为39.65%、29.15%和31.20%。     

红树林湿地系统污染生态及其净化效果的研究概况

红树林湿地系统处于淡水和海水的交互地带,具有净化水体的功能。随着大量污水、废物源源不断地排放入海,红树林湿地的水体净化功能正日益受到重视。综合国内外学者的相关研究成果,对红树林湿地系统的污染生态及其净化效果方面的研究概况进行了综述。目前,红树林湿地系统污染生态的研究主要集中在不同污染物的排放对红树林及生态环境的影响上,包括对红树植物的生长和生理生态的影响,污染物在红树植物中的累积以及污染物对红树林区沉积物、藻类、底栖动物的影响等方面上。研究结果表明,红树林对重金属、石油及污水等污染物有较强的耐性,且红树林植物和林下的土壤都有吸收多种污染物的能力,对污染物有较强的净化效果。红树林湿地系统的研究还有待于进一步深入,红树林湿地资源处于濒危状态,需加强管理和保护,所有的实验项目应在非保护区中进行。     

东北地区一次暴雪过程的诊断分析

利用观测资料对东北地区的一次暴雪过程作了物理量场的诊断分析。分析结果表明:1.本次暴雪是受到贝加尔湖强冷空气和江淮暖湿气流的共同影响而形成的;2.稳定的地面形势和空中冷性长波槽的过境为本次暴雪过程提供了强大的动力条件;3.北上江淮暖湿气流携带来自东海和渤海两个源地的充沛水汽到达东北地区,为东北暴雪的产生提供了水汽条件;4.高低空垂直切变明显、高层辐散与低层辐合相配置导致的强上升运动以及中低层深厚的正涡度产生和维持是东北暴雪形成的动力机制。     

Heavy metals in the hydrological cycle: Trends and explanation

This paper reviews the major sources and transport characteristics of heavy metals in the hydrological cycle. It is demonstrated that heavy metal releases to the environment have changed from 19th and early 20th century production-related activities to consumption-oriented factors in more recent times. The relative roles of particle size, sorption and desorption processes, partitioning and the chemical speciation of heavy metals on fine sediments are identified to understand the likely fate of heavy metals released into fluvial systems. It is argued that the spatial and temporal distribution of heavy metals in the river corridor depends not only on an understanding of metal solubility and speciation, but also on an understanding of sediment dynamics which control, for example, floodplain alluviation and the accumulation of metals in the bottom sediments of contaminated rivers, lakes and reservoirs. Existing long- and short-term records are examined to identify the current state of knowledge about the factors which affect heavy metal releases into aquatic environments. With limited exceptions, it is shown that few long-term studies of trends in heavy metal transport are available although, for some major rivers, limited data on trends in metal concentration exists. Palaeolimnological reconstruction techniques, based on an analysis of lake and reservoir sediments, are identified as a possible means of supplementing monitored records of heavy metal transport. Although numerous studies have suggested that trends in atmospheric contamination, mining and urbanization may be identified in the bottom sediment record, other research has shown that the radionuclide-based chronology and the heavy metal distribution within the sediment are more likely to be a function of post-depositional remobilization than the history of metal loading to the basin. Despite these limitations, it is shown that the incorporation of reservoir bottom sediment analysis into a heavy metal research programme, based in river corridors of Midland England, provides an opportunity to identify and quantify the relative contribution of point and non-point contributions to the heavy metal budget and to relate trends in metal contamination to specific periods of catchment disturbance.     

非线性成矿预测理论:多重分形奇异性-广义自相似性-分形谱系模型与方法

介绍了“奇异性-广义自相似性-分形谱系”(“3S”: Singularity-generalized self-Similarity-fractal Spectrum)为核心的多重分形现代成矿预测理论与模型(Multifractal Mineralization Prediction Theory and Models)的基本内容和前沿研究方向.讨论了作为非线性、复杂性理论的重要领域之一, 多重分形理论所提供的“奇异性-广义自相似性-分形谱系”等概念和相关的模型.这些新概念和模型不仅能够合理地描述成矿系统、成矿过程、成矿富集规律、矿产资源时空分布, 还提供了定量模拟和识别成矿异常(地质、地球物理、地球化学、遥感异常)的有效模型和实用方法.将多重分形原理与成矿过程、矿产资源分布规律、矿产资源信息获取研究相结合, 可形成具有良好应用前景的现代成矿预测理论与模型.采用该多重分形矿产资源预测理论和在此基础上所开发的专用地学非线性空间信息GeoDASGIS技术, 对国内外多个金属成矿区带进行了矿产资源勘查与评价, 均取得了较理想的预测效果, 表明对开展矿产资源勘查和评价是有效和可行的.