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Soil, mine tailing, and waste dump profiles above three mesothermal gold deposits in the Bohemian Massif with different anthropogenic histories have been studied. Their mineralogical, major element, and arsenic (As) contents and the contents of secondary arsenic minerals were analyzed. The As-bearing minerals were concentrated and determined using X-ray diffraction (XRD) analysis, the Debye-Scherrer powder method, scanning electron microscopy (SEM), and energy-dispersive microanalysis (EDAX). The amorphous hydrous ferric oxides (HFO), As-bearing goethite, K-Ba- or Ca-Fe- and Fe- arsenates pharmacosiderite, arseniosiderite, and scorodite, and sulfate-arsenate pitticite were determined as products of arsenopyrite or arsenian pyrite oxidation. The As behaviour in the profiles studied differs in dependence on the surface morphology, chemical and mineralogical composition of the soil, mine wastes or tailings, oxidation conditions, pH, presence of (or distance from) primary As mineralization in the bedrock, and duration of the weathering effect. Although the primary As mineralization and the bedrock chemical composition are roughly similar, there are distinct differences in the As behaviour amongst the Mokrsko, Roudný and Kaperské Hory deposits. 相似文献
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In natural waters arsenic concentrations up to a few milligrams per litre were measured. The natural content of arsenic found in soils varies between 0.01 mg/kg and a few hundred milligrams per kilogram. Anthropogenic sources of arsenic in the environment are the smelting of ores, the burning of coal, and the use of arsenic compounds in many products and production processes in the past. A lot of arsenic compounds are toxic and cause acute and chronic poisoning. In aqueous environment the inorganic arsenic species arsenite (As(III)) and arsenate (As(V)) are the most abundant species. The mobility of these species is influenced by the pH value, the redox potential, and the presence of adsorbents such as oxides and hydroxides of Fe(III), Al(III), Mn(III/IV), humic substances, and clay minerals. 相似文献
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Serkan Sayin Fatih Ozcan Mustafa Yilmaz Ali Tor Shahabuddin Memon Yunus Cengeloglu 《洁净——土壤、空气、水》2010,38(7):639-648
In this study, 5,17‐bis‐[(4‐benzylpiperidine)methyl]‐25,26,27,28‐tetrahydroxy‐calix[4]arene ( 3 ) has been prepared by the treatment of calix[4]arene with a secondary amine (4‐benzylpiperidine) and formaldehyde by means of Mannich reaction. The prepared Mannich base ( 3 ) has been grafted onto [3‐(2,3‐epoxypropoxy)‐propyl]‐trimethoxysilane‐modified Fe3O4 magnetite nanoparticles (EPPTMS‐MN) in order to obtain 5,17‐bis‐[(4‐benzylpiperidine)methyl]‐25,26,27,28‐tetrahydroxy calix[4]arene‐grafted EPPTMS‐MN (BP‐calix[4]arene‐grafted Fe3O4). All new compounds were characterized by a combination of FTIR and 1H‐NMR analyses. The morphology of the magnetic nanoparticles was examined by transmission electron microscopy. Moreover, the studies regarding the removal of arsenate and dichromate ions from the aqueous solutions were also carried out by using 5,17‐bis‐[(4‐benzylpiperidine)methyl]‐25,26,27,28‐tetrahydroxy‐calix[4]arene in liquid–liquid extraction and BP‐calix[4]arene‐grafted Fe3O4 ( 4 ) in solid–liquid extraction experiments. The extraction results indicated that 3 is protonated at proton‐switchable binding sites in acidic conditions. Hence, facilitating binding of arsenate and dichromate is resulted from both electrostatic interactions and hydrogen bonding. To understand the selectivity of 3 , the retention of dichromate anions in the presence of Cl−, NO, and SO anions at pH 1.5 was also examined. 相似文献
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The sorption of arsenate on modified-natural zeolites was investigated at varying chemical pretreatment. Zeolites were used
extensively for water softening, however, a few arsenic studies have been conducted with zeolites. Arsenic pollution of the
environment has received renewed attention due to toxicological evidence of its potential health hazards to humans. The ability
of modified natural zeolites (stilbite and laumontite) to remove inorganic anion was investigated. The zeolites used in this
work are stilbite-laumontite from Zeolitic Zone of the Corda Formation. Experiments were conducted to evaluate the relationships
of the arsenate in the modified natural zeolites. Laboratory experiments were conducted examining the effect of the sorption
of cationic surfactants and coagulant on stilbite-laumontite mixtures and on the subsequent sorption of arsenate by modified
zeolites. Removal of arsenate using hexadecyltrimethylammonium (HDTMA)-modified zeolites was satisfactory whereas ethylhexadecyldimethylammonium
(EHDDMA) and ALUM-modified zeolites were not removed with the same efficiency. 相似文献
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A laboratory batch study on arsenic sorption and desorption on guava orchard soils of Baruipur,West Bengal,India 总被引:1,自引:0,他引:1
Sudip Jyoti Sahu Bibhash Nath Sharmi Roy Biswapati Mandal Debashis Chatterjee 《Journal of Geochemical Exploration》2011
Groundwater contaminated with arsenic (As), when extensively used for irrigation, causes potentially long term detrimental effects to surface soils. Such contamination can also directly affect human health when irrigated crops, such as rice, vegetable and fruits, are used for human consumption. Therefore, an understanding of the sorption and desorption behavior of As in surface soils is of high importance, because these processes regulate the bioavailability of As in the soil environment. In this study, we have collected soils from guava orchards of Baruipur, West Bengal, and characterized soil chemistry and batch sorption and desorption behavior in the laboratory. The sorption and desorption behavior of As in the soils were examined using the Langmuir and Freundlich sorption equation. Regression analysis of the soil chemical characteristics and sorption equation parameters were also performed. The results suggest that the sorption behavior of arsenate is highly dependent on soil characteristics, specifically organic carbon, clay and Al2O3 content of the soils. Whereas desorption behavior is critically influenced by the presence of high concentrations of amorphous and/or crystalline Fe2O3 in the soils. Retention of the significant portion of As in the soils (~ 84% of the total) suggests that As in the orchard soils may not be highly bioavailable to plants for uptake. However, more detailed studies will be required to ascertain the role of individual soil components on the As sorption and desorption processes. 相似文献
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胶州湾东部水体、浮游植物和沉积物中的砷 总被引:2,自引:1,他引:2
根据胶州湾四个航次中水体的溶解态总砷c(AS)、溶解态三价砷c(AS(Ⅲ))、悬浮物总砷(Asp)、浮游植物总砷(Asph)、沉积物酸萃取态砷(SAsH)的调查数据,指出c(As)含量未超过国家一类海水水质标准,其高值区位于四方近岸,并由近岸向远岸浓度逐渐降低。由悬浮颗粒物、浮游植物和沉积物对水体中砷的富集因子,指出三者在砷的循环和迁移中起主导作用。 相似文献
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