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1.
《Applied Geochemistry》2002,17(4):353-365
Surprisingly little is known about the relationship between the labile phases removed by sequential extraction procedures and those liberated by single leaches that minimally impact the alumino-silicate matrix of solids. This investigation examines the relationship between the summed concentrations of Al, Co, Cu, Fe, Mn, Ni, Pb and Zn released by an optimized 3-step standardized sequential extraction procedure and those released by a single 0.5 M HCl leach. Thirty-nine representative soil and road deposited sediment samples were examined from an urban watershed, in Honolulu, Hawaii, which has been shown to have a high degree of traffic-associated pollution. Properties of samples analyzed varied widely and exhibited a range in cation exchange capacities from 7 to 59 cmolc/kg, pH values from 3.5 to 7.9, and organic C contents from 1 to 29%. Results indicate that the dilute HCl leach was slightly more aggressive than the sequential procedure as it removed significantly more Al, Cu, Fe, Mn and Ni; though no significant differences were observed between Co, Pb and Zn concentrations liberated by the two approaches. Both approaches showed limited dissolution of the crystal lattice with ⩽9% of the total Al liberated. Regardless of approach, element mobility was the same with the order being: Pb>Mn>Zn>Co≈Cu>Ni>Fe ∼ Al. Regression analysis indicated highly significant (P<0.0001) logarithmic relationships between the two digestion procedures, with coefficients of determination (r2) ⩾92% for all elements except Fe (54%) and Ni (64%). Further support for the strong relationships between elements liberated by both digestions was gained from geochemical contrasts between anomalous and background levels and concentration enrichment ratios. This was particularly true for Pb and Zn, the most anthropogenically enhanced trace metals in the watershed. All data indicated that a dilute HCl leach was a valuable, rapid, and cost-effective analytical tool in contamination assessment. 相似文献
2.
本文用Mg－Cr2+做榄石、辉石、尖晶石的粉晶X射线衍射数据，采取“整体图谱最小二乘Rietveld”方法计算了上述矿物的晶胞参数和摩尔体积，并对Cr2+在各晶体结构中的占位情况进行了研究。结果显示，各矿物的晶胞参数随含Cr2+量的增大而增大。据Vegard定律，推算出各端元组分铬橄榄石（Cr2SiO1）、铬辉石（Cr2SiO2O6）及立方铬尖晶石（Cr3O4）的摩尔体积分别为47．7，68．0，44．9cm3。精化结构参数指示，在橄榄石中，Cr2+随机分配在两个八面体（M1，M2）位置；在辉石中，Cr2+优先选择八面体M2位置；在尖晶石中，Cr2+占置四面体位置。这种晶体内离子分配可从离子半径差别或晶体场稳定能大小得到解释。 相似文献
3.
Hun-Bok Jung Seong-Taek Yun Bernhard Mayer Soon-Oh Kim Seong-Sook Park Pyeong-Koo Lee 《Environmental Geology》2005,48(4-5):437-449
Transport and sediment–water partitioning of trace metals (Cr, Co, Fe, Pb, Cu, Ni, Zn, Cd) in acid mine drainage were studied
in two creeks in the Kwangyang Au–Ag mine area, southern part of Korea. Chemical analysis of stream waters and the weak acid
(0.1 N HCl) extraction, strong acid (HF–HNO3–HClO4) extraction, and sequential extraction of stream sediments were performed. Heavy metal pollution of sediments was higher
in Chonam-ri creek than in Sagok-ri creek, because there is a larger source of base metal sulfides in the ores and waste dump
upstream of Chonam-ri creek. The sediment–water distribution coefficients (K
d) for metals in both creeks were dependent on the water pH and decreased in the order Pb ≈ Al > Cu > Mn > Zn > Co > Ni ≈ Cd.
K
d values for Al, Cu and Zn were very sensitive to changes in pH. The results of sequential extraction indicated that among
non-residual fractions, Fe–Mn oxides are most important for retaining trace metals in the sediments. Therefore, the precipitation
of Fe(–Mn) oxides due to pH increase in downstream sites plays an important role in regulating the concentrations of dissolved
trace metals in both creeks. For Al, Co, Cu, Mn, Pb and Zn, the metal concentrations determined by 0.1 N HCl extraction (Korean
Standard Method for Soil Pollution) were almost identical to the cumulative concentrations determined for the first three
weakly-bound fractions (exchangeable + bound to carbonates + bound to Fe–Mn oxides) in the sequential extraction procedure.
This suggests that 0.1 N HCl extraction can be effectively used to assess the environmentally available and/or bioavailable
forms of trace metals in natural stream sediments. 相似文献
4.
Cinzia Bettiol Lorenzo Stievano Mariangela Bertelle Francesca Delfino Emanuele Argese 《Applied Geochemistry》2008
Acid extractions represent a simple and effective tool for the assessment of metal contamination, origin and bioavailability in the aquatic environment. Optimized microwave-assisted procedures utilizing two extractions (8 M HNO3 and 1 M HCl) were developed. Particular attention was given to the evaluation of efficiency and selectivity of the developed procedures. This involved an examination of the sediment and the extraction residues by Mössbauer spectroscopy and X-ray diffractometry. These instrumental approaches were used to identify the geochemical phases associated with acid decomposition. Microwave digestion with 8 M HNO3 produced an efficient solubilization of the most important metal-bearing phases and left unaffected only the minerals (quartz, feldspars, muscovite) with a negligible metal content, thus providing a good estimate of the total metal concentrations. The 1 M HCl extraction, despite the limitation due to the incomplete solubilization of pyrite and to the partial dissolution of sheet silicates, represents a simple and effective technique for providing an estimate of the bioavailable metal fraction in sediments. The combined use of the two microwave-assisted acid extractions can provide a rapid and simple approach for the risk assessment of metal-polluted sediments. 相似文献
5.
The processes that determine the rate of chalcopyrite leaching are central to understanding how chalcopyrite (CuFeS2) behaves under the environmentally adverse conditions of acid rock drainage. To this end the effect of the acid anion on chalcopyrite leach rates using a variety of acidic media (H2SO4, HClO4, HCl and H2SO4 with 0.25 M NaCl) under carefully controlled solution conditions (pH 1 and 2, Eh 750 mV (SHE) and 75 °C) has been examined. These conditions have been chosen to enable sufficient leach rates for accurate experimental determination and to compare to the previous mechanistic analysis carried out by Harmer et al. (2006).Extensive surface analysis of leach residues demonstrated that variations in the surface speciation could not be responsible for the observed variations in leach rate. The rate of Cu release, however, was found to be first order with respect to Fe3+ activity and inversely proportional with respect to H+ activity to the power of 0.7:
6.
《Applied Geochemistry》2004,19(6):947-955
Nine partial decomposition procedures and a total digestion treatment were applied to road-deposited sediments. The objective was to define a parsimonious, time-efficient decomposition procedure that (1) has limited impact on the alumnio-silicate matrix and/or refractory-associated fractions, (2) has metal recoveries independent of CaCO3 content, and (3) produces high anthropogenic signals for known contaminants (e.g., Cu, Pb and Zn). The 9 digestions varied from weak single reagents (0.11 M acetic acid) to strong multi-step procedures (BCR 3-step plus aqua regia). Eight metals were examined: Al, Co, Cu, Fe, Mn, Ni, Pb, and Zn. Cold (room temperature) 0.5 M HCl shaken over a 1-h period with a solid-to-solution ratio of 1 g:20 ml, was judged superior based on the defined criteria. This simple, rapid treatment had limited impact on the residual matrix (mean and 95% confidence interval for Al recovery was 6±1%); recoveries of all elements examined were independent of CaCO3 content; the treatment produced high mean extraction efficiencies for Cu (58±9%), Pb (84±5%), and Zn (73±7%), and produced high anthropogenic signals. Thus, dilute HCl can be widely recommended as an optimal partial decomposition procedure for assessing non-residual fractions of complex solid media. 相似文献
7.
黄土醋酸淋溶实验及其碳酸盐组分的地球化学特征 总被引：5，自引：0，他引：5
选择性的化学淋溶实验 ,广泛用于沉积物的地球化学研究中。通过对比 1mol/L的盐酸和醋酸两种溶剂对黄土和古土壤的淋溶效果 ,发现 1mol/L的醋酸能选择性淋溶黄土和古土壤中碳酸盐组分 ,对硅酸盐、铁的氧化物等影响很小。在确定溶剂后 ,以 1mol/L醋酸溶液选择性淋溶了洛川剖面 4 3个黄土和古土壤样品 ,通过分析淋溶液的组成 ,得出黄土和古土壤中碳酸盐组分的平均成分 (wB)为 :MgO 1.71% ,MnO 670× 10 - 6 ,Sr 4 90× 10 - 6 。淋溶结果较好地反映了黄土-古土壤剖面的风化成壤程度 ,其中醋酸淋溶液中MnO含量能更好地反映当时的古气候信息。 相似文献
8.
Sediments from MANOP sites M and H in the eastern tropical Pacific Ocean can be partitioned into operationally defined phases by means of a sequential leach procedure. This paper reports the results of the first leach in the sequence, an acetic acid solution buffered as p H 5 with sodium acetate. This leach is designed to remove carbonate-bound and sorbed cations. The only cation bound in a consistent ratio to calcium in the carbonate is strontium. The molar ratio is 2 × 10?3. In contrast, transition metals are sorbed onto the surfaces of other sedimentary particles. The proportions sorbed range from 2 to 10% of the total manganese, about 10% of the total nickel and copper, and less than 1% of the total iron. The pool of sorbed metals in surface sediments is sufficiently large and the rate of biological stirring is sufficiently rapid for this metal reservoir potentially to dominate the porewater reservoir in supplying metals to ferromanganese nodules. A simple model for nodule growth based upon transfer of metals through this reservoir suggests that only 1% of the sedimentary sorbed metals within a radius of 2 to 9 cm is required to support typical nodule growth rates. 相似文献
9.
Sylvie Philippe Céline Leterme Sandric Lesourd Lucie Courcot Udo Haack Jacinthe Caillaud 《Applied Geochemistry》2008
The Seine estuary possesses a heavily industrialised catchment area that contrasts significantly with that possessed by the smaller Authie estuary. For both of these northern French estuaries, Pb isotopic compositions and concentrations have been determined on specimens of Hediste diversicolor (ragworms) and on HCl leachates performed on related mudflat sediment. Three sampling campaigns were completed in 2003. As expected, the reactive Pb obtained by 1 M HCl leaching, shows higher concentrations and a more anthropogenic signature in samples from the Seine estuary than in samples from the Authie. However, neither of the two sites is free from the influence of anthropogenic Pb. Possible contaminant sources are discussed through comparisons with previously published data. For the more highly contaminated Seine estuary, most of the ragworm Pb signatures are similar to those of the sediments. In contrast, ragworms from the Authie site exhibit a higher proportion of anthropogenic Pb than the corresponding sediments. Various hypotheses are discussed to explain this significant discrepancy: (1) analytical artifacts, (2) migration of ragworm populations, (3) diet and feeding behaviour, and as the most likely explanation (4) an unsuitable leaching method for the extraction of bioavailable Pb. 相似文献
10.
《Applied Geochemistry》2006,21(8):1335-1346
The chemical speciation of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in marine sediments from two coastal regions of Singapore (Kranji in the NW, and Pulau Tekong in the NE) was determined using the latest version of the 3-step sequential extraction procedure, as described by the European Community Bureau of Reference (1999). To obtain a mass balance, a fourth step, i.e., digestion and analysis of the residue was undertaken using a microwave-assisted acid digestion procedure. The total content of all metals except for Pb in sediments was greater in Kranji than in Pulau Tekong. All metals, except Cd were more mobile and bio-available in Kranji, where metals were present at higher percentages in the acid-soluble fractions (the most labile fraction). In sediments from Kranji, the mobility order of the heavy metals studied was Cd > Ni > Zn > Cu > Pb > Cr, whereas sediments from Pulau Tekong showed the same order for Cd, Ni, Pb and Cr, but had a reverse order for Cu and Zn (Cu > Zn). The highest percentages of Cr, Ni and Pb were found in the residual fractions in both Kranji (78.9%, 54.7%, 55.9%, respectively) and Pulau Tekong (82.8%, 77.3%, 62.2%, respectively), meaning that these metals were strongly bound to the sediments. Results are consistent with findings from Barcelona, Spain where similar results for Cr and Ni have also been reported for marine sediments. The sum of the 4 steps (acid-soluble + reducible + oxidizable + residual) was in good agreement with the total content, which implies that the accuracy of the microwave extraction procedure in conjunction with the GFAAS analytical method is assured. 相似文献
11.
Sixty sediment samples with a wide range of heavy‐metal concentrations and sediment textures were collected from Sydney Harbour. The samples were extracted with 1M HCl, 0.05M EDTA and HClO4/HNO3 and analysed by flame atomic absorption spectrometry for Zn, Pb, Cu and Cd. 1M HCl extracted a large proportion of heavy metals in oxic sediments (60–100%), whereas the extractability of metals with 0.05M EDTA was generally lower (by ～20%). Extractability was unrelated to the level of contamination or to sediment texture. The extractability of Cu in anoxic sediments was substantially lower with 1M HCl (～20%) and 0.05M EDTA (～10%) than with HClO4/HNO3. The extractability of Pb with 0.05M EDTA was also reduced in anoxic sediments (to ～70%). The use of weak extractants, in particular 1M HCl, is recommended by the recently introduced ANZECC and ARMCANZ interim sediment‐quality guidelines. These extractants are believed to provide a better measure of the bioavailable metal content than strong acid extractants. In this study, anoxic, sulfidic environments had a major influence on metal extractability with weak extractants. The implication of this is that the number of samples requiring further testing, as stipulated by the guidelines, would be significantly reduced in anoxic sediments. 相似文献
12.
《Applied Geochemistry》1999,14(5):655-667
Sediments sampled at a hydrocarbon-contaminated, glacial-outwash, sandy aquifer near Bemidji, Minnesota, were analyzed for sediment-associated Fe with several techniques. Extraction with 0.5 M HCl dissolved poorly crystalline Fe oxides and small amounts of Fe in crystalline Fe oxides, and extracted Fe from phyllosilicates. Use of Ti-citrate-EDTA-bicarbonate results in more complete removal of crystalline Fe oxides. The average HCl-extractable Fe(III) concentration in the sediments closest to the crude-oil contamination (16.2 μmol/g) has been reduced by up to 30% from background values (23.8 μmol/g) as a result of Fe(III) reduction in contaminated anoxic groundwater. Iron(II) concentrations are elevated in sediments within an anoxic plume in the aquifer. Iron(II) values under the oil body (19.2 μmol/g) are as much as 4 times those in the background sediments (4.6 μmol/g), indicating incorporation of reduced Fe in the contaminated sediments. A 70% increase in total extractable Fe at the anoxic/oxic transition zone indicates reoxidation and precipitation of Fe mobilized from sediment in the anoxic plume. Scanning electron microscopy detected authigenic ferroan calcite in the anoxic sediments and confirmed abundant Fe(III) oxyhydroxides at the anoxic/oxic boundary. The redox biogeochemistry of Fe in this system is coupled to contaminant degradation and is important in predicting processes of hydrocarbon degradation. 相似文献
13.
沉积物中黑碳的提取和测定方法 : 误差分析和回收率实验 总被引：6，自引：0，他引：6
介绍了从沉积物中提取黑碳的一种误差较小的改进方法，并对实验误差及引起误差的原因进行了详尽的分析和探讨，同时给出了方法的回收率。经过未均匀处理样品的平行实验，得到实验结果的总体偏差为8．89％，其中个别样品的偏差可达10％－20％；在样品进行了均匀处理后，得到平行实验的总体偏差为3．29％，HCl-HF单步处理的总体偏差为1．96％，而K2Cr2O7氧化处理单步实验的总体偏差为2．50％。其中回收率实验表明，黑碳的回收率可达80％以上。由此可见，所取样品具有代表性，是准确测定沉积物黑碳含量的前提。 相似文献
14.
贵州省矿业开发引起的环境问题及其成因探讨 总被引：9，自引：0，他引：9
矿业开发给贵州省造成严重的生态环境问题,主要包括环境污染,矿业荒漠化和环境地质灾害。虽然贵州省矿产开发的历史比较悠久,但解放前的生态破坏和矿业污染仅局限在个别地区,解放后出现的三次大规模资源环境破坏,给贵州省矿业可持续发展带来严重影响,特别是改革开放以来矿山资源的无序开发对环境的危害最重。导致贵州省矿业环境问题的主要因素包括：矿产资源价值的严重扭曲,乡镇企业的超常规发展,部分政府官员的权力寻租,以及资源导向型的脱贫模式等。 相似文献
15.
To investigate the distribution pattern and controlling factors of rare earth elements (REEs) in riverine sediments, river mouth sediments were collected at five geographically different rivers around the Yellow Sea. Two- (1 M HCl leached and residual fractions) and five-step sequential extraction schemes (the SEDEX method) were applied to size-separated sediments < 20 µm. For the total REE composition, patterns normalized relative to the upper continental crust (UCC) showed light REE (LREE) and middle (MREE) enrichments in the Korean river sediments and MREE enrichment in the Chinese river sediments. LREE and MREE enrichments in 1 M HCl leached fractions played a major role in the distribution patterns of the total compositions in all the river sediments. About half of LREE enrichment in Korean river sediments was explained by the residual fraction. Comparison of the REE composition with major elements (Al, Fe, Ca, P) in each fraction of the SEDEX scheme revealed that MREE enrichment could be explained by reactive iron minerals, including goethite and hematite, although REE/Fe ratios showed different trends among the rivers due to different major REE-host iron minerals. After extracting reactive irons, authigenic phosphate, and carbonate, the sequential 1 M HCl fraction indicated that LREE enrichment in Korean river sediments may have originated from clay minerals, such as chlorite. These observations suggest that LREE enrichment may be a good tracer, while MREE enrichment should be used cautiously considering diagenetic modification, when using the REE composition to identify the sources of terrestrial materials. 相似文献
16.
The effects of elevated pH, ionic strength, and temperature on sediments in the vadose zone are of primary importance in modeling contaminant transport and understanding the environmental impact of tank leakage at nuclear waste storage facilities like those of the Hanford site. This study was designed to investigate biotite dissolution under simulated high level waste (HLW) conditions and its impact on Cr(VI) reduction and immobilization. Biotite dissolution increased with NaOH concentrations in the range of 0.1 to 2 mol L-1. There was a corresponding release of K, Fe, Si, and Al to solution, with Si and Al showing a complex pattern due to the formation of secondary zeolite minerals. Dissolved Fe concentrations were an order of magnitude lower than the other elements, possibly due to the formation of green rust and Fe(OH)2. The reduction of Cr(VI) to Cr(III) also increased with increased NaOH concentration. A homogeneous reduction of chromate by Fe(II)aq released through biotite dissolution was probably the primary pathway responsible for this reaction. Greater ionic strengths increased biotite dissolution and consequently increased Fe(II)aq release and Cr(VI) removal. The results indicated that HLW would cause phyllosilicate dissolution and the formation of secondary precipitates that would have a major impact on radionuclide and contaminant transport in the vadose zone at the Hanford site. 相似文献
17.
Series of α, β, ω and (ω-1) hydroxy fatty acids (FAOHs) were determined in several freshwater and brackish water lacustrine sediments in Japan. Analytical procedure used was digestion of the solvent-extracted sediment with HF/HCl followed by solvent and saponification extraction of the residue. Abundances of α/β and ω-FAOH determined by this procedure were 2–3 times higher than those obtained by single alkaline saponification and of the same order with those provided by HCl hydrolysis. Major portion of α/β-FAOH was obtained by solvent extraction of the acid-treated sediments, while subsequent alkaline saponification was needed for the majority of ω-FAOH to be recovered. Thus determined FAOHs comprised 33–61% (Av. = 42%) of the “bound” acid constituents in the lacustrine surface sediments. The α/β and ω-FAOH composition was principally the same among the samples examined, except for relative proportions of the iso to anteiso C15 and C17 ß(α)-FAOH, which showed significant variations in the ranges of 0.30–1.1 and 0.46–1.5, respectively. In the holomictic lakes, the ratios together with the same ratios of the “bound” branched monocarboxylic acids tended to decrease with increasing water depth of the lakes, suggesting that the ratios may indicate an extent of the early diagenetic alteration of the bacteria-derived lipids either in water column or in surface sediment. 相似文献
18.
19.
John W. Morse Dwight K. Gledhill Karen S. Sell Rolf S. Arvidson 《Aquatic Geochemistry》2002,8(1):3-13
In sediments from the continental slope of the Northern Gulf of Mexico, generally,the degree of iron pyritization (DOP) is low (<0.1) and dissolved sulfide is belowdetection limits (5 M), whereas dissolved Fe is typically about 50 to100 M. Therefore, the dissolution of kinetically reactive iron minerals generallydominates over the rate of sulfide production in sediments throughout this region.However, in sediments where hydrocarbons have been added via seepage from thesubsurface, dissolved-Fe is undetectable, DOP can approach 1, and high concentrationsof dissolved sulfide (up to 11 mM) are commonly present. Even though thesesediments have high total reduced sulfide (TRS) concentrations (typically 150 to370 mol gdw-1), their average C/S ratio is about 4 times that of normal marine sediments reflecting the major input of hydrocarbons. DOP is significantly (20%) higher when calculated using reactive-Fe extracted by citrate dithionite than by cold 1N HCl. This difference is primarily due to the greater extraction efficiency of the cold HCl method for silicate-Fe. TRS tends to rise to a maximum, and remains close to constant even at high (mM) dissolved sulfide concentrations. These TRS concentrations, therefore, represent the size of the ``kinetically' reactive-Fe pool during early diagenesis. 相似文献
20.
Bhabesh C. Sarkar Bashab N. Mahanta Kalyan Saikia Pradip R. Paul Gurdeep Singh 《Environmental Geology》2007,51(7):1177-1196
A study on geo-environmental quality assessment in Jharia coalfield, India, has been attempted using multivariate statistical
analysis and geographic information system (GIS) modelling techniques. Water quality index, calculated for each sample network
station in the study area to assess the suitability of water for human consumption, revealed very poor to poor quality surface
water and mine water. Air quality indexing indicated that there is no sample station with clean air as per the Indian standards,
which indicate the hazardous air quality. Multi-criteria evaluation (MCE), a potential GIS tool, has been applied to the delineation
of various degrees of stressed villages in terms of quality of life (QoL). The role of various geo-environmental parameters
such as quality of groundwater, surface water, mine water and air together with village population densities has been emphasized
for delineation of the environmentally stressed villages in Jharia coalfield. The integrated cluster analysis and MCE approach
provide an improved means to geo-environmental quality assessment in Jharia coalfield in terms of QoL. The assessment study
is aimed to be used for future coal mining, ensuring ecologically sustainable industrial development, particularly in a coalfield. 相似文献