Temperature and pH Dependence of Some Metals Leaching from Fly Ash of Municipal Solid Waste

Abstract. Municipal solid waste combustion leads to concentration of various metals in the solid residue (fly ash) remaining after combustion. These metals pose serious environmental hazard and require proper handling and monitoring in order to control their harmful effects. Leachability of some metals from fly ash was examined in fly ash and Milli-Q water mixture (liquid-to-solid ratio, 100) under various temperature and pH conditions in the laboratory. The leaching experiments conducted for 24 hours showed that pH was generally more important than temperature in controlling the amount of metals leached out of the fly ash. However, at a given pH, rise in temperature led to different degree of (usually one to two fold) enhanced or reduced leaching of metals. Owing to amphoteric nature of oxides of Al, Cr, Pb and Zn, these metals often yielded typical pattern of increase and decrease in their concentrations with change in pH. The extent of leaching of Cr and Pb in our experiments suggests that decrease of pH to acidic range in the case of Pb and to neutral to acidic range for Cr over a long period of storage of fly ash at solid waste dumping site may facilitate leaching of these metals from fly ash, leading to contamination of groundwater to the level that exceeds beyond the level permitted by the environmental laws.     

Quantification of mineral matter in the Argonne Premium Coals using interactive Rietveld-based X-ray diffraction

The mineral matter in the eight reference North American coal samples of the Argonne Premium Coal series has been investigated on a quantitative basis using X-ray diffraction (XRD) techniques. X-ray diffraction data obtained from electronic low-temperature (oxygen–plasma) ash (LTA) residues, from ashes produced by heating the coals in air at 370°C, and also from the raw coals themselves, were evaluated using an interactive data processing system ( ™) based on Rietveld interpretation methods. The results from the three types of material (LTA, 370°C ash and raw coal) were compared for each sample. This allowed the components present in the raw coals in crystalline form to be recognised separately from mineral artifacts produced, particularly in the low-rank coals, from interaction of organically associated elements (Ca, S, etc.) during the two ashing processes.After the allowance for the production of any artifacts, the quantitative mineral assemblages identified from XRD of the raw coals were found to be consistent, even for coals having a relatively low ash percentage (around 5%), with the results obtained from the respective mineral concentrates prepared by the ashing methods. The effects of heating the coal to 370°C could also be distinguished, relative to the raw coal or the LTA, through changes in components such as pyrite and the clay minerals.Although some areas of uncertainty exist, particularly with magnesium in the low-rank coals, the calculated chemical compositions of the coal ash derived from the mineral mixtures identified for each coal were also found to be consistent with the results of direct chemical analysis of the respective coal ash materials.     

华北晚古生代煤中有机硫的赋存状态及其成因

为揭示煤中有机硫的赋存状态及其地质成因,采用电子探针微区分析和硫同位素分析技术对华北地区山西大同、太原西山、霍州以及安徽淮南４个矿区的８个层晚古生代的煤层进行了研究,海水的作用对有机硫的聚集起着十分重要的影响。煤的不同显微组分中有机硫的质量分数存在明显差异,镜质组中有机硫的质量分数高于其在惰质组的质量分数。硫在煤中的聚集是一个逐渐累积的过程,有机硫的聚集一般滞后于黄铁矿硫的聚集。泥炭沼泽条件控制着     

青藏高原草地土壤有机碳库及其全球意义

定量分析了青藏高原各类草地0～0.65m深度范围内有机碳储量,结果表明:青藏高原总面积为1.6027×10hm²的草地有机碳量达到335.1973×10⁸tC,其中以高原草甸土和高原草原土有机碳积累量为主,两者之和达到232.36×10⁸tC,占全国土壤有机碳量的23.44%,是全球土壤碳库的2.4%.在有机碳储量分析的基础上,按土壤碳释放的两种主要途径:土壤呼吸作用和土地利用方式变化与草地退化,对草地土壤碳排放进行了估算,揭示出青藏高原草地土壤通过呼吸每年排放的CO₂达到11.7×10⁸tC·a^-1,约占中国土壤呼吸总量的2.3%,明显高于全国乃至全球平均值;近30a来,青藏高原草地土壤由于土地利用变化和草地退化所释放的CO₂估计约有30.23×10⁸tC.保护青藏高原草地对于全球变化意义重大.定量分析了青藏高原各类草地0～0.65m深度范围内有机碳储量,结果表明:青藏高原总面积为1.6027×10hm²的草地有机碳量达到335.1973×10⁸tC,其中以高原草甸土和高原草原土有机碳积累量为主,两者之和达到232.36×10⁸tC,占全国土壤有机碳量的23.44%,是全球土壤碳库的2.4%.在有机碳储量分析的基础上,按土壤碳释放的两种主要途径:土壤呼吸作用和土地利用方式变化与草地退化,对草地土壤碳排放进行了估算,揭示出青藏高原草地土壤通过呼吸每年排放的CO₂达到11.7×10⁸tC·a^-1,约占中国土壤呼吸总量的2.3%,明显高于全国乃至全球平均值;近30a来,青藏高原草地土壤由于土地利用变化和草地退化所释放的CO₂估计约有30.23×10⁸tC.保护青藏高原草地对于全球变化意义重大.     

黄河三角洲内陆到潮滩土壤中碳、氮元素的梯度分布规律

黄河三角洲是我国典型的通过黄河冲积泥沙填海造陆形成的近代沉积区。区域受到黄河冲积、沉积等自然过程和农业耕种熟化等人类活动的双重影响。本研究通过在黄河三角洲地区内陆到河口海湾不同距离采集典型土壤类型剖面发生层样品,探讨土壤有机碳、总氮等生源要素的空间分布规律,为阐明我国典型海岸带地区陆源碳、氮的输送及循环特征提供基础依据。研究结果表明,黄河三角洲内陆与河口地区呈现出完全不同的土壤碳、氮分布规律。表层土壤碳、氮含量在黄河沿岸及三角洲南部均表现出由陆向海逐级递减的空间分布特征,而在黄河刁口流路和清水沟流路沿行水方向有梯度升高的趋势。内陆地区土壤碳、氮与盐分呈一定的负相关关系,表明土壤碳、氮主要受到耕作熟化过程的影响;而在河口地区两者呈显著的正相关关系（p〈0.01）,表明靠近海湾地区土壤碳、氮积累可能受到细颗粒泥沙沉积和滩涂湿地厌氧等环境影响。表层土壤碳、氮比变幅在3.6~8.6之间,说明该地区土壤有机质分解较快,不利于有机碳的积累。土壤剖面中,一些特殊发生层如红色夹黏层、黑色泥炭层对土壤碳、氮的富集具有明显的作用,其中红色夹黏层的土壤碳、氮含量接近耕层土壤。总之,黄河三角洲土壤在耕作垦殖、泥沙沉积等综合作用下形成的空间分布格局以及剖面特征发生层是影响碳、氮封存、释放和增汇等循环过程的关键驱动因素。     

Formation Mechanism of High Quality Marine Source Rocks—Coupled Control Mechanism of Geological Environment and Organism Evolution

High quality marine source rock (HQMSR) is the key prerequisite for medium to large hydrocarbon accumulations. However, the forming mechanism remains unclear. On the basis of the in-vestigation for the geodynamic setting of the Middle-Upper Yangtze during the Early Cambrian in dif-ferent spatial scales and the analysis of trace elements, the main controlling factors of the development of high quality marine source rock are discussed, with specific consideration of the burial rate of the organic matter. The ...     

An Overview of Dissolved and Suspended Matter Fluxes in the Loire River Basin: Natural and Anthropogenic Inputs

The spatial and temporal distributions of major elements were investigated in the surface waters and in associated suspended matter at two sites of the upper Loire basin (Orleans and Brehemont) between 1995 and 1998.According to geochemical and isotopic patterns, the dissolved load appears to result from a process of mixing rainwater inputs, weathering processes of carbonate and silicate bedrock, and agricultural and urban inputs. Natural inputs influence 60% of water chemical composition at both sites. Annual dissolved fluxes were estimated to be 1300 10³ t/y at Orleans and 1620 10³ t/y at Brehemont. Major elements are transported mainly in the dissolved fraction. After correcting for atmospheric and anthropogenic inputs, the silicate specific export rate was calculated to be 11 t/y/km² throughout the basin and the carbonate specific export rate to be from 47 t/y/km² at Orleans to 23 t/y/km² at Brehemont.The suspended load appears to result from at least two particle reservoirs: a silicate reservoir and a carbonate reservoir. The silicate reservoir has a detrital origin, mainly during periods of high flow, while the carbonate reservoir has a detrital origin during periods of high flow and an authigenic origin during periods of low flow. Of the total annual flow of suspended matter, this authigenic material represents 16% at Orleans, 25% at Brehemont and 37% in the fluvial part of the estuary. After correcting authigenic inputs, the specific export rate due to mechanical weathering was estimated to be 8 t/y/km² throughout the Loire basin.     

一种适用于沉积有机质族组分分离的微型柱色谱法

硅胶-氧化铝柱色谱是广泛采用的沉积有机质组分分离方法。但在常规柱色谱分离方法中,存在吸附剂、溶剂使用量过大、烷烃/芳烃组分交叉严重等问题。介绍一种微型柱色谱分离法,其分离效果与常规方法的效果基本相同或略有改善,吸附剂用量与样品的比例由100～250降低为25～50,洗脱溶剂与样品的比例由1800～4600降低至250～500。同时,操作程序进一步简化,分析成本和对环境的污染程度大幅度降低。     

沸石强化过滤的中试及生产性试验研究

对新型水处理材料沸石强化常规给水处理工艺进行了中试和生产性试验,并与石英砂滤料做了对比.中试结果表明粒径为0.80-1.20mm沸石对浊度、氨氮、有机物都表现出良好的去除效果,过滤时的水头损失、反冲洗强度明显小于石英砂,不仅能满足反冲洗要求,还可节省反冲洗水量,降低运行成本.在生产性试验条件下,沸石对浊度、氨氮、耗氧量的去除率分别为95%、83%和39%.因此,在当前水源水遭到污染的情况下,用沸石替代石英砂滤料可明显改善水质,在不增加处理构筑物的情况下,对给水处理工艺可起到强化作用     

民乐锰矿生物矿物学特征初步研究

民乐锰矿矿石中发现蓝藻化石六、七种,其中石囊藻细胞(Eontophysalis)和色球藻目(chroocacean)中的矿物质为钙、镁、锰的碳酸盐系列矿物。本文综合了偏光显微镜、生物显微镜、电子显微镜及X射线衍射分析,无机、有机化学分析资料,找到了蓝藻与碳酸锰矿物的密切空间关系和成生联系。引用了关于生物成矿的观点,论述本区生物形成矿物的作用过程和相关的矿物种类。提出菱锰矿形成的生物—生物化学成因的观点。