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71.
72.
Lallan Prasad Gupta Hodaka Kawahata Mio Takeuchi Hidekazu Ohta Yoshiro Ono 《Resource Geology》2005,55(4):357-372
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. 相似文献
73.
《International Geology Review》2012,54(7):904-916
Located in the western Yangtze Block, the Qingshan Pb–Zn deposit, part of the Sichuan–Yunnan–Guizhou Pb–Zn metallogenic province, contains 0.3 million tonnes of 9.86 wt.% Pb and 22.27 wt.% Zn. Ore bodies are hosted in Carboniferous and Permian carbonate rocks, structurally controlled by the Weining–Shuicheng anticline and its intraformational faults. Ores composed of sphalerite, galena, pyrite, dolomite, and calcite occur as massive, brecciated, veinlets, and disseminations in dolomitic limestones. The C–O isotope compositions of hydrothermal calcite and S–Pb–Sr isotope compositions of Qingshan sulphide minerals were analysed in order to trace the sources of reduced sulphur and metals for the Pb–Zn deposit. δ13CPDB and δ18OSMOW values of calcite range from –5.0‰ to –3.4‰ and +18.9‰ to +19.6‰, respectively, and fall in the field between mantle and marine carbonate rocks. They display a negative correlation, suggesting that CO2 in the hydrothermal fluid had a mixed origin of mantle, marine carbonate rocks, and sedimentary organic matter. δ34S values of sulphide minerals range from +10.7‰ to +19.6‰, similar to Devonian-to-Permian seawater sulphate (+20‰ to +35‰) and evaporite rocks (+23‰ to +28‰) in Carboniferous-to-Permian strata, suggesting that the reduced sulphur in hydrothermal fluids was derived from host-strata evaporites. Ores and sulphide minerals have homogeneous and low radiogenic Pb isotope compositions (206Pb/204Pb = 18.561 to 18.768, 207Pb/204Pb = 15.701 to 15.920, and 208Pb/204Pb = 38.831 to 39.641) that plot in the upper crust Pb evolution curve, and are similar to those of Devonian-to-Permian carbonate rocks. Pb isotope compositions suggest derivation of Pb metal from the host rocks. 87Sr/86Sr ratios of sphalerite range from 0.7107 to 0.7136 and (87Sr/86Sr)200Ma ratios range from 0.7099 to 0.7126, higher than Sinian-to-Permian sedimentary rocks and Permian Emeishan flood basalts, but lower than Proterozoic basement rocks. This indicates that the ore strontium has a mixture source of the older basement rocks and the younger cover sequence. C–O–S–Pb–Sr isotope compositions of the Qingshan Pb–Zn deposit indicate a mixed origin of the ore-forming fluids and metals. 相似文献
74.
Release of heavy metals during weathering of the Lower Cambrian Black Shales in western Hunan,China 总被引:8,自引:0,他引:8
Bo?PengEmail author Zhaoliang?Song Xiangling?Tu Meilian?Xiao Fucheng?Wu Huanzhe?Lv 《Environmental Geology》2004,45(8):1137-1147
Weathering of heavy metal enriched black shales may be one of the most important sources of environmental contamination in areas where black shales are distributed. Heavy metal release during weathering of the Lower Cambrian Black Shales (LCBS) in western Hunan, China, was investigated using traditional geochemical methods and the ICP-MS analytical technique. Concentrations of 16 heavy metals, 8 trace elements and P were measured for samples from selected weathering profiles at the Taiping vanadium ore mine (TP), the Matian phosphorous ore mine (MT), and Taojiang stone-coal mine (TJ). The results show that the bedrock at these three profiles is enriched with Sc, V, Cr, Co, Ni, Cu, Zn, Pb, Th, U, Mo, Cd, Sb, Tl, and P. Based on mass-balance calculation, the percentages of heavy metals released (in % loss) relative to immobile element Nb were estimated. The results show significant rates of release during weathering of: V, Cr, Co, Ni, Cu, Zn, U, Mo, Cd, Sn, Sb, and Tl for the TP profile; Sc, Cr, Mn, Co, Ni, Cu, Zn, Pb, Th, Cd, and Sn for the MT profile; and Sc, Mn, Co, Ni, Zn, Th, Cd, Sn, and Tl for the TJ profile. Among these heavy metals, Co, Ni, Zn, Cd, and Sn show very similar features of release from each of the three weathering profiles. The heavy metals released during weathering may affect the environment (especially topsoil and surface waters) and are possibly related to an observed high incidence of endemic diseases in the area. 相似文献
75.
Sorption is an important process in the modelling and prediction of the movement of heavy metals in unsaturated clay barriers. This experimental study investigates the effect of pH changes in the acidic range on the sorption characteristics of heavy metals such as: lead, copper and zinc in an unsaturated soil. A series of one-dimensional coupled solute and moisture leaching column tests, using different heavy metal solutions, were conducted on an unsaturated illitic soil at varying pH values. Variations of volumetric water content (VWC) with distance were measured for different time durations, and concentrations of heavy metals in the liquid and solid phases were analysed. Partitioning coefficient profiles of contaminants along the soil column were determined for each individual layer in the soil.
Results from column leaching tests showed that the sorption characteristics of heavy metals are controlled by many factors which should be taken into consideration, i.e. the VWC, time of wetting, soil pH, and the influent heavy metal concentrations. Simplification of Kd as a constant and of the VWC as a linear function cannot be considered a good assumption and may lead to an improper evaluation of the sorption phenomena and also to serious errors in predicting contaminant transport through unsaturated soils. 相似文献
76.
Trace Metal Solid State Speciation in Aerosols of the Northern Levantine Basin,East Mediterranean 总被引:3,自引:0,他引:3
Mustafa Koçak Nilgun Kubilay Barak Herut Malcolm Nimmo 《Journal of Atmospheric Chemistry》2007,56(3):239-257
An established three stage sequential leach scheme was applied to a series of selected high volume aerosol samples (n = 35) collected from the Turkish Eastern Mediterranean coastline (Erdemli). Samples were selected according to their air
mass back trajectory history to reflect the contrasting mixtures of aerosol material present in the Eastern Mediterranean
marine aerosol. Two populations were adopted, those samples which were classed as “anthropogenic” and those which were “Saharan”
dominated aerosol populations. Applying the three stage leach it was possible to define the proportion for each of the considered
metals (Al, Fe, Cu, Pb, Cd, Zn and Mn) present in the (a) “exchangeable” (b) “carbonate / oxide” and (c) “refractory” phases,
representing novel solid state aerosol speciation data for this marine system. Clear trends were established, conforming with
data from previous studies with mainly crustal derived metals (Al and Fe) being present in the refractory phases (Al > 88%;
Fe > 84%) and those influenced by anthropogenic sources being dominating in the exchangeable phase, although for these metals
the variability was comparatively high (12–64%; 19–85%; 40–100% for Zn, Pb and Cd, respectively). For the majority, greater
exchangeable fractions were present the lower the crustal source contribution to the aerosol population, whereas the “refractory”
fraction exhibited contrasting behaviour. This was illustrated by the novel application of the mixing diagram, presenting
each of the three speciation stages against the corresponding percent anthropogenic contribution to each collected sample.
Zn, Pb and Cd all illustrated progressive decrease in the percent exchangeable with increasing crustal contribution to the
aerosol population. The percent exchangeable was discussed in terms of its use to represent the upper limit of the bioavailable
fraction of metal associated with the aerosol, post deposition. The mixing diagram approach enabled the prediction of the
residual fractions for Cd, Pb and Zn (41 ± 4%; 62 ± 4% and 82 ± 5%, respectively,) in Saharan end-member material. 相似文献
77.
Concentrations of trace elements and heavy metals (Al, As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Sb, Se, Sr, V and Zn) in
the Danjiangkou Reservoir, the water source area of the Middle Route of China’s interbasin South to North Water Transfer Project,
were analyzed using an Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES) and compared with the national and
international standards for drinking water. The results indicated that concentrations of As, Pb, Sb and Se in the Reservoir
exceeded the standards and they would pose health risk for residents in the region and the water receiving areas of the interbasin
water transfer project. Spatial and temporal variability of the trace elements and heavy metals in the Reservoir implies their
mixed sources of natural processing and anthropogenic activities in the upper drainage of the Reservoir. The research results
would help develop water resource management and conservation strategy for the interbasin water transfer project. 相似文献
78.
The Malter Reservoir is situated about 30 km south of Dresden (eastern Germany) in a historical mining area of the eastern
Erzgebirge. It was built in 1913 for the protection from floodwaters, droughts and for generating electricity. The river Rote
Wei?eritz is the main source of clastic input into the lake. Geochemical and sedimentological data of gravity-and piston-cores,
recovered from the deepest point of the lake, document the environmental history of the drainage area since 1963. 137Cs dating gives an average sedimentation rate of ∼2.9 cm/year. Within the whole core, heavy metals are strongly enriched (parentheses
refer to enrichment factors as compared with average shale): cadmium (290), silver (140), bismuth (90), antimony (25), lead
(21), zinc (14), tin (13), uranium (9), tungsten (9), molybdenum (5), copper (4), thallium (3) and chromium (2). Enrichments
are detectable for the whole registered time-period of 81 years. Peaks of up to 27 mg/kg silver, 37 mg/kg bismuth, 91 mg/kg
cadmium, 410 mg/kg chromium, 240 mg/kg copper, 20 mg/kg molybdenum, 14000 mg/kg phosphorus, 740 mg/kg lead, 6,5 mg/kg antimony,
74 mg/kg tin, 52 mg/kg tungsten and 1900 mg/kg zinc reflect local events caused by human impact. Inputs from different pollution
sources at different times are represented by highly variable elemental concentrations and ratios within the core. High pH
values within the water and the sediment column, the large adsorption capacity of the fine-grained Corg.-rich sediment, and the presence of low Eh-values and sulphide ions in the sediment prevent the remobilisation of the toxic
elements. Erosion of these contaminated sediments during floods, channel flows or resuspension during removal of the sediments
may lead to a downstream transfer of pollutants. Contents of P and Corg., as well as diatom abundance, indicate a change from oligotrophic to eutrophic conditions in the lake during ∼1940–1950.
This was mainly caused by high agricultural activity in the drainage area. Reduced contents of Cu, Zn, Cd and Cr since the
reunification of East and West Germany are obviously caused by increasing environmental protection measures, such as wastewater
purification and especially the closing of contaminating industries.
Revision received: 23 September 1999 · Accepted: 17 December 1999 相似文献
79.
80.
高海拔地区由于特殊的自然环境对气候变化和营养输入的响应十分敏感.在人类活动逐渐加强的背景下,高山湖泊高分辨率的沉积物记录了人与自然相互作用的演变过程.选取云南西北部典型高山湖泊——错恰湖,获取长度37 cm的连续湖泊沉积序列,基于铅铯测年法得到年代深度模型,并对湖芯样品进行总有机碳、总氮及正构烷烃的多指标测定和元素测量,结合气象监测数据探讨分析错恰湖的有机质来源和流域环境演化特征.根据气候代用指标的变化,两百年来错恰湖泊环境及区域气候演化可以分成4个主要阶段:1807-1900年:湖泊水位上升、湖面扩大,有机质丰度下降,有机质以外源贡献为主,内源比例上升;1900-1950年:湖泊水位开始下降、湖面收缩,有机质丰度下降,外源有机质来源增加;1950-1982年:湖泊水位下降、湖面进一步收缩,有机质丰度下降,外源输入比例继续增加;1982-2007年:湖泊水位下降、湖面收缩,有机质含量上升且以陆源输入为主,同时内源贡献比例开始增加.在元素测定结果中,人类活动对应了湖泊沉积重金属含量变化的3个阶段:1950年以前,重金属含量低且稳定,可视作自然背景阶段,人类影响忽略不计;1950年以后,湖泊流域工农业逐渐发展,人为干扰凸显;直到1982年以后,冶炼工业的进步加强了重金属的污染态势,并通过大气传输沉降被湖泊沉积物记录.错恰湖沉积记录的分析讨论在总结该区域气候环境演化历史的同时,加深了对气候人类活动湖泊生态系统相互作用过程的理解,为高山湖泊响应人类活动影响提供了证据. 相似文献