Characterization of Kolar gold field mine tailings for cyanide and acid drainage

The gold mining process at Kolar gold field (KGF) mines has generated about 32 million tons of tailings. Gold was extracted from the mined ores using cyanidation technique that involved dissolution of gold in the ore by water soluble alkali metal cyanides (example, sodium cyanide or potassium cyanide). Of the several dumps that received the mine tailings only the Kennedy’s Line dump was active prior to closure of the KGF mines in the year 2000. The Kennedy’s Line dump received sulfide bearing tailings in slurry form that comprised of spent ore and process water bearing soluble alkali metal cyanide. Depending on the pH of the tailing slurry, the free cyanides may exist as aqueous hydrogen cyanide that can escape to the atmosphere as hydrogen cyanide gas or occur as soluble cyanide (CN⁻) ions that can be leached by infiltrating water to the sub-surface environment. Additionally, the presence of pyrite minerals in the Kennedy’s Line dump makes them susceptible to acid drainage. This study examines the potential of gold tailings of Kennedy’s Line dump to release cyanide ions (CN⁻) and acid drainage to the sub-surface environment by performing physico-chemical and leaching tests with tailing samples collected from various depths of the dump, sub-surface soil samples beneath the dump and groundwater samples from vicinity of Kennedy’s Line dump. The chemical mechanisms responsible for the ambient cyanide and pH levels of the tailing dump, sub-surface soil samples and groundwater are also inferred from the laboratory results.     

Cd, Cr, Cu, Ni and Pb in the water column and sediments of the Ob-Irtysh Rivers, Russia

Concentrations of Cd, Cr, Cu, Ni and Pb were determined in filtered water, suspended particulate matter, and bottom sediments from a 2000 km section of the Ob and Irtysh Rivers. Dissolved Cd, Cr, Cu and Ni concentrations are similar to, or higher than, results from other Russian Arctic and large world river-estuaries. Concentrations of Cd, Cr, Cu, Ni and Pb in suspended particulate matter are generally comparable to results from other Russian Arctic and large world rivers and estuaries. Comparison of trace metal ratios in crustal material and suspended particulate matter and bottom sediment suggests that the source of Cr, Cu and Ni is continental weathering. Particulate Cd and Pb are elevated relative to their crustal abundance, suggesting a source of these metals to the Ob-Irtysh in addition to continental weathering.     

渤海滩涂湿地沉积物胶体对石油污染物的吸附特征

为了研究滩涂湿地沉积物胶体对石油污染物的吸附作用,根据渤海天津段滩涂湿地沉积物的结构和组成,选择代表性沉积物提取胶体,对胶体的粒径、ζ电位、电泳淌度进行了表征,系统测定胶体对可溶性油吸附的动力学曲线和吸附等温线。结果表明,滩涂湿地沉积物胶体平均粒径为345.04nm;ζ电位、淌度中值分别为-0.47mV、-0.03μs-1V-1cm;交换吸附动力学模式适用于滩涂沉积物胶体对可溶性油的吸附作用,其吸附平衡时间约为20~24h,胶体对可溶性油吸附速率常数为9.434L/(g·h);胶体对可溶性油的等温吸附线为直线型,当水相中石油烃浓度低于某一值时,胶体不但不吸附溶液中的石油烃,反而使胶体中的残留石油烃释放出来。     

Review on Researches of Legacy POPs and Emerging POPs in the Arctic Regions

The specific geographic location and natural conditions of the Arctic region play a significant role in the global climate change. As a result of perennial low temperature, simple ecological structure, and fragile ecosystem and weak stability in the Arctic, Persistent Organic Pollutants (POPs) accumulating from the region of middle and low latitudes may cause tremendous pressure in the arctic ecological environment. Therefore, the research of POPs in the Arctic region is not only conducive to more in-depth understanding of POPs distribution and transformation process in the global range, but to reasonably assess the harm of human activities on the arctic ecological environment. Thus, in the past 40 years, especially after nine new kinds of emerging organic contaminants being added to the list of Stockholm Convention in 2009, more and more scientific community and general public have pay attention to the research of POPs in the Arctic region. At present, the understanding of legacy POPs in the Arctic is limited, and the research of emerging POPs is in the initial stage. This paper aimed to summarize some conclusions and implications of the research, and focused on the occurrence level, historical evolution, bioaccumulation and source of POPs in atmosphere, waters, sediments and organisms in the Arctic region. Finally, the future changes and key scientific problems of POPs in the Arctic region were proposed.     

Emerging organic contaminants (EOCs) in freshwaters in Dunedin,New Zealand

Emerging organic contaminants (EOCs) in New Zealand freshwaters are not well documented for regulatory assessments. We collected water and sediment samples for measurement of 26 EOC compound concentrations at four waterways within the city of Dunedin (Otago province). Compounds measured ranged from stimulants and depressants to pain-killers and insect repellants. Sampling was conducted before and after the student ‘Orientation Week’ at the University of Otago. Most compounds were below detection limits in all samples. However, caffeine, carbamazepine, cotinine and DEET were all measured at concentrations above detection limits. In general, concentrations of EOC compounds were ～20% higher following the influx of students to the University though student effects varied by site and additional sampling is needed to better assess temporal variation in concentrations. These data indicate that some EOCs are present in New Zealand freshwater ecosystems.     

地下水有机污染治理技术现状及发展前景

概述了现有的几种地下水有机污染治理方法：抽出处理、注气－抽取土壤气、内在生物净化、流线控制、多技术结合法、生物治理、吸附、原位反应墙等工作原理和治理效果;简要分析了地下水有机污染治理技术存在的问题和发展前景。     

Is there a significant diffusive “salt-pump mechanism” for the transport of organic contaminants from the marine environment into fresh water aquifers? A discussion contribution

We analyse recent claims of an additional risk of diffusive intrusion by marine organic contamination (OC) into coastal aquifers, and discuss the activity-driven “salt-pump mechanism” which is claimed to accelerate this diffusion. The reported accelerations of transport of OC out of saltwater are far too large to be due to activity effects on simple diffusion. There probably is a small acceleration of diffusion out of saltwater, but there is no direct experimental evidence for this. Possible experimental artefacts are suggested. Larger effects on diffusion in the literature are shown to be not relevant to this problem. Diffusion of suspended OC, present in the experiments, is too slow to be significant; however, this suspended material is shown to have serious implications for the proposed interpretation of the results. Until these results are better understood, no conclusions about any possible environmental implications can be drawn from them.

水环境中新污染物快速检测技术研究进展

国内外广泛关注的新污染物主要包括抗生素、内分泌干扰物、全氟或多氟化合物等污染物质,这些污染物通过径流、扩散、渗透等多种途径进入水体环境。由于新污染物多具有生物累积性、生物毒性及环境持久性等特征,对水生生物、人体健康和生态安全构成潜在威胁,存在环境风险,因此,国家对其污染现状开始进行调查。随着中国新污染物污染状况调查评价工作的开展,快速、灵敏的检测方法成为研究热点。本文基于近年文献重点评述了水环境中新污染物的检测方法,并对方法的性能和优缺点作了对比。结果表明：①目前新污染物的检测方法以大型仪器检测方法为主。仪器检测方法的检测浓度低、精度高,对设备的要求高,从采样到测试分析得到结果的周期长,不适用于新污染物的现场快速检测。②传感检测技术和免疫分析技术逐步应用于新污染物的快速检测。其中电化学传感器和酶联免疫分析法相对成熟,应用较多,具有设备简单、检测时间短,灵敏度和精确度良好等优点,可开展现场快速检测。本文认为,①快速检测技术多针对单一污染物进行检测,而实现同时检测多种污染物质还需进一步研究;②多种检测技术相结合可以达到更好的检测效果,是未来新污染物检测的发展方向;③利用新型材料改良检测方法、降低检出限、提高灵敏度和精确度实现新污染物快速检测是未来研究的难点和重点。     

煤中干酪根的成熟度与菲的吸附行为间的关系

将云南先锋褐煤采用热模拟的实验方法制得一组成熟度不同的煤,并将煤中的干酪根用于对菲的吸附研究.结果表明:随着干酪根成熟度的增加,有机质结构变得紧密、刚硬,还原性和芳香性增强.不同成熟度干酪根的内部结构和性质与菲的吸附行为间存在一定的关系.随着干酪根内部结构的刚性和芳香性的增强,吸附等温线的非线性逐渐增强.对于成熟度相对较低的干酪根,随着成熟度的增加,吸附容量逐渐增大,而对于成熟度相对较高的干酪根,随着成熟度的增加,吸附容量却减小.     

Application of generalized contaminant retardation factor to a multi‐phase system

In this study, a generalized contaminant retardation factor applicable to a multiphase system where various types of colloids exist simultaneously with contaminants is derived and incorporated into an equilibrium model which is successfully applied to experimental data for which phenanthrene was used as hydrophobic organic contaminants and dissolved organic matter (DOM) or bacteria as mobile carriers. Based on the parameter values for the experimental data regarding the association of phenanthrene with solid matrix, DOM and various bacterial isolates, numerical experiments are performed to examine the transport behaviour of hydrophobic organic contaminants in various types of the multiphase system. Numerical experiments demonstrate that the extent of contaminant transport enhancement depends on the adsorption affinity of the colloid, its concentration and its mobility, and that the importance of a third phase to contaminant transport needs to be evaluated carefully with respect to the relevance of experimental conditions applied to realistic environmental conditions. Copyright © 2003 John Wiley & Sons, Ltd.