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1.
Undifferentiated meteorites (chondrites) have the same relative abundances of refractory lithophile elements (Ca, Al, Ti, Sc, REE, etc.), despite variable absolute concentrations. The reasonable assumption of chondritic ratios among refractory elements in the bulk Earth is used to constrain the chemical composition of the upper mantle in the following way: Correlations of the compatible refractory elements Ca, Al, Ti, Sc and Yb with MgO are worldwide very similar in suites of spinel-lherzolite xenoliths from basaltic rocks. Such suites represent upper mantle material depleted to differing degrees by extraction of partial melts. From these refractory elements vs. MgO correlations, ratios of pairs of refractory elements were calculated at various MgO contents. Chondritic and ratios were only obtained for MgO contents below 36%. A chrondritic ratio requires an MgO content above 35%. We therefore accept 35.5% as the most reasonable MgO content of undepleted upper mantle. This MgO content is slightly below the spinel-lherzolite with the lowest measured MgO content (36.22%). The corresponding Al2O3 content of 4.75% is higher than in previous estimates of upper mantle composition. The concentrations of other elements were obtained from similar correlations at a MgO content of 35.5%. The resulting present upper mantle composition is enriched in refractory elements by a factor of 1.49 relative to Si and Cl and by a factor of 1.12 for Mg relative to Si and Cl. These enrichments are in the same range as those for the Vigarano type carbonaceous chondrites. The Mg/Mg + Fe ratio of 89 is slightly lower than previous estimates.The ratio in spinel lherzolite suites is, however, uniformly higher worldwide than the chondritic ratio by about 15%. Orogenic peridotites as well as komatiites appear to have similar non-chondritic ratios. It is therefore suggested that this non-chondritic ratio is a characteristic of the upper mantle, possibly since the Archean. A minor fractionation of about 4% of garnet in an early, global melting event (deep magma ocean?) is presented as the most likely cause for the high . In this case the addition of 4% of such a garnet component to the undepleted present upper mantle would be required to obtain the composition of the primordial upper mantle. The of this primordial mantle would be 15% higher than that of the undepleted present upper mantle, resulting in an enrichment of refractory elements of 1.70 ( relative to Cl) for the primordial upper mantle. 相似文献
2.
Alteration of basaltic glass: Mechanisms and significance for the oceanic crust-seawater budget 总被引：1，自引：0，他引：1
Alteration of basaltic glass to palagonite is characterized by a nearly isomolar exchange of SiO2, Al2O3, MnO, MgO, CaO, Na2O, P2O5, Zn, Cu, Ni, Cr, Hf, Sc, Co and REE for H2O and K2O, whilst TiO2 and FeO are passively accumulated during removal of the remaining cations. The network forming cations Al and Si are removed from the glass in proportion to the gain in Ti and Fe, whilst the other cations do not show a significant relationship to the amount of Ti and Fe accumulation. Sr isotopic data show that during palagonite formation approximately 85% of the basaltic Sr is lost to the hydrous solutions and 40% of seawater Sr is added to the glass, yielding an average loss of the same order of magnitude as of the network forming cations. Losses and gains of oxides yield an average increase of +105% TiO2.K, Rb, and Cs show high increases, but and ratios indicate two different alteration processes: (1) formation of palagonite involves a drastic decrease in these ratios, indicating structural similarities between palagonite and smectite; (2) surface alteration of glass is characterized by an increase in and ratios, probably best interpreted as sorption of alkalies in ratios approximating those of seawater.The total fluxes involved in alteration of glass in the upper portion of the oceanic crust are estimated from the modal abundance of palagonite in the oceanic crust and the abundance of the vein materials smectite and carbonate. Smectite and carbonates act as a sink for a significant portion of the elements liberated up during alteration of basaltic glass except for Na and Al, which are probably taken up by zeolites and/or albite, possibly hidden in the macroscopic estimate of carbonate. Formation of the observed quantity of secondary phases requires additional sources for Si, Fe. Ca and K. K is provided in excess from the inflowing seawater at reasonable water/rock ratios. The remaining excess Ca, Si and Fe required may be derived by alteration of interstitial glass and breakdown of anorthite rich plagioclase and titano-magnetite, and/or by supply of deeper seated metamorphic reactions. 相似文献
3.
Oxidation products of Mn(II) in lake waters 总被引：1，自引：0，他引：1
Oxygenation of Mn(II)-rich water samples taken from two English lakes (Esthwaite Water, Cumbria, and Rostherne Mere, Cheshire) during the summer months caused the precipitation of Mn-oxide, the process being catalysed by particulate matter. The Mnoxide formed resembles vernadite (δ-MnO2) with regard to: (1) Mn oxidation state (> 3.6 in all but one case); and (2) its fine morphology (crumpled thin sheets) as determined by electron microscopy. The precipitates are, however, rather amorphous to X-rays, giving only very weak reflections which cannot be assigned unequivocally. Electron probe microanalysis shows the presence of a number of other elements in the Mn-containing phase. The most abundant is Ca (Ca/Mn weight ratio ), others are Mg, Si, P, S, Cl, K, Ba and Fe. The precipitates contain much organic matter (20–30 wt.%) but little appears to be associated directly with the Mn phase. Only small amounts (～ 1 wt.%) of humic substances are present. Some but not all of the specimens examined had the gross morphology of Metallogenium, a Mn-depositing bacterium.Naturally occurring Mn-oxides present in Esthwaite Water during the summer resemble, the products of oxygenation in their fine morphology and contents of other elements. Mn-oxides present during the winter are somewhat different morphologically. In one summer sample of particulate matter from Esthwaite Water no Mn-oxide could be found by electron microscopic examination, but Mn was found concentrated in bacteria. This observation, the rapid rates of oxidation and the high Mn oxidation states, suggest that bacteria might play a rôle in catalysing the oxidation of Mn(II). 相似文献
4.
沉积物的元素地球化学特征是对沉积盆地水体环境以及古气候条件变化的响应。本文根据元素（Al、Fe、Mg、Ca、K、Na、P、V、Ni、Co、Cr、Cu、Zn、Sr、Ba、Cd、Li、Mn、Pb、Ti）的含量及其比值（Al/Ti、Fe/Mn、Sr/Ba、Mg/Ca、Sr/Ca、Na/Ca、V/Cr、Ni/Co、Ni/V）的变化，对三水盆地古近系心组红岗段生油层的沉积条件进行了系统分析。心组红岗段下部（亚段A）表现为较稳定的地球化学特征。各元素丰度及其比值指示这一时期陆源输入持续较高、且物源组成变化不大。由于海水入侵的影响，湖盆水体盐度相对较高，底部水体以弱氧化条件为主，O2-H2S界面位于水/沉积物界面附近。红岗段中上部（亚段B、C）的元素地球化学特征变化较为频繁且幅度很大，反映古气候和湖盆沉积条件的迅速变迁。在潮湿气候条件下，沉积物的地球化学特征表现为以Al、Ti为代表的外源元素含量及其比值较高，而Mg、Ca等盆内化学沉积元素含量较低。古氧气指标指示底部水体为还原环境，有利于有机质保存。因而，相应于较高的有机碳含量。在间歇性干旱时期，陆源输入减少，外源元素含量及其比值显著降低。随着蒸发作用的加强，水体盐度加大，内源元素丰度以及Mg/Ca、Sr/Ba、Sr/Ca和Na/Ca比值大幅度上升。底部水体为氧化环境，O2-H2S界面多位于水/沉积物界面或沉积物中。上述两种气候条件在红岗段中上部沉积时期交替出现。红岗段沉积后期由于淡水的长期输入，湖水出现逐渐淡化趋势。 相似文献
5.
A Fe-Ti-Mn-silicate microspherule from the heavy mineral fraction of crushed geological samples from an underground mine (Kellyam gold deposit, Yakutia) was examined by transmission electron microscopy. The 400-μm microspherule has a complex chemical composition and contains the following elements (in order of decreasing content): O, Ti, Si, Mn, Fe, Al, Mg, Ca, and K. The material of the micro-spherule shows a polyphase structure and chemical heterogeneity with separation into amorphous oxide-silicate (SiO2) and crystalline metallic (α-Ti + FeTi) constituents. The spherical shape and the character of internal heterogeneity suggest that the microspherule was formed owing to the rapid solidification of a melt droplet. The nanoscale heterogeneity of the microspherule is a consequence of a two-stage process. (1) Liquid immiscibility in the initial melt droplet before its solidification resulted in the incomplete spatial separation of Si + Al and Ti + Fe + Mn and appearance of SiO2 globules with admixtures of Al, Ca, K, Mg, Ti, Fe, and Mn approximately 100 nm in size. (2) Chemical heterogeneity developed subsequently both within the globules and within the matrix at the stage of melt solidification or after the solidification. The second-stage chemical heterogeneity was manifested in (a) the separation of heavy minor element oxides (Ti, Fe, and Mn) from the light elements Si, Al, K, Ca, and Mg(?) within the globules and (b) the separation of the matrix material into crystalline metallic (α-Ti + FeTi) and amorphous oxide-silicate [SiO2-MgO-Mn3O4(?)-Fe2O3(?)-TiO2(?)] parts. The obtained results do not rule out the possibility of formation of such microspherules during drilling operations. 相似文献
6.
Cynthia R.P. Maris Michael L. Bender Philip N. Froelich Ross Barnes Nile A. Luedtke 《Geochimica et cosmochimica acta》1984,48(11):2331-2346
Pore water profiles of Ca, Mg, F, PO4?3 and Mn in the Galapagos Mounds Hydrothermal Field are believed to reflect, in part, upwelling of hydrothermal solutions through the sediments. Concentration-depth profiles in a low heat flow area just north of the Mounds Field display diagenetic changes typical of those found in pore waters underlying highly productive surface waters, consistent with the inference of no water flow or very slow downwelling () of bottom water through these sediments. Rates of upward advection calculated from Mounds Field pore water profiles of Ca, Mg, and F profiles agree well with each other, averaging about 1 cm/yr in the pelagic sediments near the mounds and 15–30 cm/yr within the hydrothermal mounds themselves. The upward advection also modifies the shape of PO4?3 and Mn profiles.Advection rates inferred from the pore water data are generally in reasonable agreement with those made from heat flow data.The higher Ca and lower Mg, F, PO4?3 and Mn concentrations in Mounds Field pore waters (compared with those of the low heat flow area) suggest chemical exchange between the solution and basalt prior to upwelling. Li+, K+, Rb+, Sr++ and SO4? concentrations are indistinguishable from bottom water. This suggests very high effective water/rock ratios during the reactions which produced the upwelling solutions, perhaps due to extensive prior alteration of basalt adjacent to the flow path of water through the crust Inferred reaction temperatures are between 70–150°C. 相似文献
7.
太平洋北部铁锰结核富集区沉积物的元素地球化学特征 总被引：2，自引：1，他引：2
本文对太平洋北部铁锰结核富集区沉积物的元素地球化学作了较为详细的研究。因子分析提供的信息表明,元素的分布主要受三个因子控制:（1）粘土及Fe、Mn氧化物水化物胶体的吸附作用;（2）生物化学作用过程有关的自生沉积作用;（3）海底页岩风化及附近海区的火山喷发作用。元素的来源:（1）Fe、Mn、Cu、Co、Ni、Zn、Cr、Cr、Mg、Al、Ti、K共生,主要来自粘土吸附;（2）C有机、N、Sr、Na及Si、Ca、Sr主要来自生物化学过程沉积;（3）Pb主要来源于岩石碎屑（火山喷发碎屑）。 相似文献
8.
The chemistry of suspended matter in Esthwaite Water,a biologically productive lake with seasonally anoxic hypolimnion 总被引：1，自引：0，他引：1
Ten detailed vertical water column profiles were taken between April and November, 1979, in Esthwaite Water (English Lake district), a lake with high biological productivity and a seasonally anoxic hypolimnion. Measurements of the major-element particle composition (organic C, P, S, Si, Al, Ti, K, Mg, Ca, Fe, Mn, and Ba) and hydrochemical constituents (temperature, pH, dissolved oxygen, total suspended load, dissolved Fe, Mn, P, and Ba) were carried out. These have revealed new information about the mechanisms and kinetics of biogeochemical cycles in a lake.Pronounced seasonal cycles exist in which large excess concentrations (those unsupported by detrital components) of particulate organic C, Fe, Mn, P, S, Mg, K, Ba, and Ca are being generated and lost in situ in the water column (15m deep). In the epilimnion these elements (excepting Fe and Mn) are incorporated into the organic components of growing phytoplankton during the spring and summer. Simultaneously, in the hypolimnion there is a build-up and then a decrease in the excess concentrations of particulate C, P, S, Mg, K, Ba and Ca; this cycle is due to the indirect involvement of these elements with the iron redox cycle. As the hypolimnion becomes anoxic, dissolved ferrous Fe is released from the sediments and large concentrations of excess particulate iron (III) oxides accumulate; these oxides act as adsorbing substrates for the above mentioned elements. As conditions become more reducing, these same elements are solubilized as the iron (III) oxide particles are reduced to dissolved ferrous iron.Adsorption equations are derived from the field data which relate the concentration of excess particulate Fe to those of POC, P, S, Ca, Mg, Ba, and K. At the last stages of anoxia (before the lake overturns) large populations of bacteria and the formation of iron sulfide particles control the concentrations of excess particulate C, S, P, Mg, K, and Ca. 相似文献
9.
The objective of this study was to quantify by experiments the initial seawater–suspended basaltic glass interactions following the 1996 outburst flood from the Vatnajökull glacier, Iceland. The altered basaltic glass dissolved in seawater as recorded by the Si release from the glass. The dissolved concentrations of Na, Ca, Si, Ba, Cd, Co, Cu, Hg, Mn, Ni and total dissolved inorganic N increased with time but the concentrations of Mg, K, S, Sr, Fe, Pb and Zn decreased. Calculated 1 to 10 day fluxes for Si range from 38,000 tons/day to 70,000 tons/10 days. The fluxes for other major elements are more uncertain, but the positive flux (release from suspended matter to seawater) of Ca and Na, and negative flux of Mg, K and S are greater than the Si flux. 相似文献
10.
The concentrations of noble gas isotopes of He, Ne and Ar have been measured in eight mineral separates of the Bruderheim chondrite. The cosmic-ray-produced nuclides 21Ne and 38Ar were correlated by a computer least-squares fitting program with the elemental composition in each separate of potential targets for nuclear production yielding the following production equations: ; with elemental concentrations in weight per cent and k equal to the reciprocal of the cosmic-ray exposure age of Bruderheim. The P(S)/P(Cr + Mn + Fe + Ni) weight production ratio for 3He was determined to be 1.53; relative productions of 3He from O, Mg and Si and 21Ne from Al proved to be incalculable. 相似文献
11.
12.
Detailed vertical profiles were taken in the north basin of lake Windermere between July and November 1980. Measurements were made of temperature, dissolved oxygen, pH, total suspended load and the major-element composition (organic C, Al, Fe, Mn, Si, S, P, Ca, Mg, Ba and K) of suspended particles.Excess concentrations (those reactive phases not supported by detrital phases) of particulate S, P, Ca, Mg, Ba and K are highest in the epilimnion due to their incorporation into the growing phytoplankton. These elements are associated with planktonic organic matter and are rapidly recycled in the upper 25 m of this 60 m oxic lake. This is documented by the decrease with depth of both excess concentrations of S, P, Ca, Mg, Ba and K and their ratios to POC. Large concentrations of excess particulate Si occur in the hypolimnion as the result of the settling out of diatom skeletal matter produced near the surface during the spring bloom. These siliceous particles do not contain significant quantities of excess particulate S, P, Ca, Mg, Ba and K. This observation supports the conclusion that organic matter is the important recycling matrix for these inorganic elements.Elevated concentrations of excess particulate Mn at depth indicate that there is a Mn-redox cycle operating in the lake. 相似文献
13.
A. L. Ramanathan P. Vaithiyanathan V. Subramanian B. K. Das 《Estuaries and Coasts》1993,16(3):459-474
Major ion chemistry of water and elemental geochemistry of suspended and surficial sediments collected from the Cauvery Estuary were studied to understand the geochemical processes in this tropical estuarine system. Specific conductance (EC), total dissolved solids (TDS), and total suspended matter (TSM) increased conservatively with increasing chlorinity. In general, SO4 2?, Na, K, Ca, and Mg showed an increasing trend while H4SiO4 and PO4 3? showed a decreasing trend toward the sea. Additional removal mechanisms operating for these ions in the Cauvery Estuary have been identified based on observed concentrations. Factor analysis pointed out the sources contributing to the observed trends in estuarine water chemistry. POC and PON decreased toward the high chlorinity zone. TSM in the Cauvery Estuary were mostly of inorganic nature. Stable carbon isotope values showed that the carbon was equally of marine and terrestrial origin and helped to delineate the contribution of river water and seawater. The ? mean size (a logarithmic grain size scale commonly used by sedimentologists) indicated that the surficial sediments were primarily comprised of coarse and silt, whereas suspended sediments were principally silt and clay. Suspended sediments were enriched in clays compared to surficial sediments. Quartz and feldspar were abundant among detritals while chlorite, kaolinite, and montmorillonite were dominant among clays. Silicon was the most abundant element in the sediments followed by Al, Ca, Na, K, Fe, Mn, and P. Heavy metals were enriched in the suspended sediments compared to the surficial bottom sediments as follows: Fe = 3.5, Mn = 7.4, Pb = 1.1, Zn = 15.2, Cu = 7.4, and Cr = 4.0. The levels of Cd, Cr, Zn, and Fe increased up the middle reaches and then decreased toward the sea due to urban effluent and fertilizer input. Size fractionation studies indicated that the metal concentration in the finer fraction was 50% higher by mass than the coarse silt and fine silt fractions. Chemical fractionation studies showed that the abundance of metals were in the order of residual > organic/sulfide > carbonate > Fe/Mn oxide > exchangeable fractions. 相似文献
14.
The authors have studied an Albian glauconite—phosphate—carbonate ore in the Sierra de Espuña (Murcia), situated in the betic Cordilleras, nappe of Malaga. The geochemical data concern 76 samples from which the following elements were titrated by spectro-photometric methods: P, Fe, Ti, Al, Mg, Mn, Ca, Na, K, Zn, Li, Ni, Cr and Sr.The percentages of SiO2, P2O5, Al2O3, K2O and total Fe with respect to the insoluble fraction and the CaCO3, Mn, P2O5 amounts permit of partly explaining the phosphate—glauconite bond. The pH and Eh conditions, deduced from vertical variations in the chemistry, are associated with the mineralogic evolution of the glauconites.The authors define the paleoenvironment of this glauconite—phosphate ore deposit. They clearly separate the environment of the genesis from that of sedimentation of the grains. The sedimentation of carbonate—phosphate—glauconitic particles occurred in a confined environment without continental debris. These grains were formed in proximity of the shelf edge.The phosphate and carbonate supplies are attributed to upwelling of deep waters. 相似文献
15.
The carbon isotopic composition of 66 inclusion-containing diamonds from the Premier kimberlite, South Africa, 93 inclusion-containing diamonds and four diamonds of two diamond-bearing peridotite xenoliths from the Finsch kimberlite, South Africa was measured. The data suggest a relationship between the carbon isotopic composition of the diamonds and the chemical composition of the associated silicates. For both kimberlites similar trends are noted for diamonds containing peridotite-suite inclusions (P-type) and for diamonds containing eclogite-suite inclusions (E-type): Higher δ13C P-type diamonds tend to have inclusions lower in SiO2 (ol), Al2O3 (opx, gt), Cr2O3, MgO, (ol, opx, gt) and higher in FeO (ol, opx, gt) and CaO (gt). Higher δ13C E-type diamonds tend to have inclusions lower in SiO2, Al2O3 (gt, cpx), MgO, (gt), Na2O, K2O, TiO2 (cpx) and higher in CaO, (gt, cpx).Consideration of a number of different models that have been proposed for the genesis of kimberlites, their xenoliths and diamonds shows that they are all consistent with the conclusion that in the mantle, regions exist that are characterized by different mean carbon isotopic compositions. 相似文献
16.
N.C.N Stephenson 《Lithos》1977,10(1):9-27
The compositions of coexisting hornblendes and biotites from amphibolite and granulite facies gneisses from the south coast of Western Australia were controlled by host rock composition, paragenesis, metamophic grade, pressure, and oxygen fugacity. The Mg/(Mg + Fe2+) and Mn/Fe2+ ratios in both minerals and possibly the Alvi contents of the hornblendes are related to host rock compositions. Metamorphic grade appears to influence, perhaps only indirectly, the Ti, Mn, and Fe3+ contents of both minerals and possibly the hornblende Ca content. The higher Ti and lower Mn contents of the granulite facies hornblendes and biotites are attributed to their coexistence with pyroxenes, whereas their lower Fe3+/(Fe2+ + Fe3+) ratios are probably due to lower oxygen fugacity in the granulite facies environment. Grade-related colour variations in both minerals were controlled by their Ti/Fe2+ and Fe3+/(Fe2+ + Fe3+ ratios. The relatively low Alvi contents of the hornblendes suggest low- to moderate-pressure metamorphism.Variations in element distribution coefficients are related to variations in mineral compositions rather than metamorphic grade. Thus KD(Aliv ?Si) is related to the Aliv andedenite alkali contents of the hornblendes, KD(Fe2+ ?Mg) to the distributions of Aliv ?Si and Alvi + Ti + Fe3+, KD(Mn) to the Mn contents of both minerals, and KD(Alvi) to the Alvi contents of the biotites. 相似文献
17.
Chemical and mineralogical analyses of a well-controlled suite of ferromanganese encrustations from the Line Islands Archipelago (Central Pacific) suggest that they represent purely hydrogenous deposits—i.e. they have formed through the slow accumulation of trace metal-enriched oxides directly from the water-column. Mineralogically they consist predominantly of δMnO2 and amorphous FeOOHxH2O. Compositionally, they are similar to δMnO2 nodules from adjoining basinal areas but are enriched in both Mn (mean = 20.4%, max = 29.3%) and Co (mean = 0.55%, max = 1.57%). δMnO2 is the most important trace metal bearing phase; strong associations are noted between it and Co, Mo, Ni, Zn, and Cd, whilst only Be is associated specifically with FeOOH. V, Sr and Pb are partitioned between the authigenic oxide phases, whilst Ti most probably occurs as TiO2xH2O. Cu is contained in both aluminosilicate contaminant phases and Fe oxide phases. These relations are considered to reflect the differing scavenging behaviour of Mn and Fe oxides in the water column.Crusts from ~1–2 km are enriched in Mn and the Mn-related elements and exhibit higher ratios than deeper crusts, which are compositionally constant. The higher ratios may result from a supply of Mn from continental borderland sediments at these depths, which is transported horizontally by advective-diffusive processes. Since manganophile elements are enriched relative to Mn in the 1–2 km crusts, it is considered that the supply of Mn is scavenged by existing oxides, is oxidised and effectively occludes them. A higher proportion of oxide particles thus exhibit Mn oxide scavenging properties in the 1–2 km depth zone. The increased vertical flux of Mn resulting from the supply at ~1–2 km is not reflected by higher ratios in deeper crusts, so that the vertical flux of oxides is not simply related to the standing crop. The ratios of the crusts thus reflect the composition of suspended oxides at similar depths. 相似文献
18.
作物产量与土壤环境的关系 总被引：11，自引：1，他引：10
作物的产量与土壤元素中Ｎ、Ｐ、Ｋ、Ｎａ、Ｃａ、Ｍｇ、Ｓ、Ｆｅ、Ｍｎ、Ｃｕ、Ｚｎ、Ｂ、Ｍｏ、Ｖ、Ｃｏ、Ｎｉ、Ｃｒ、Ｐｂ、Ｃｄ、Ｈｇ、Ｓｅ、Ｆ、ＴＩ、Ｂａ、Ｔｅ、Ｔａ、Ｓｒ、Ｔｉ、Ｓｉ等元素及稀土、有机质、酸碱度和含水量、含盐量密切有关。 相似文献
19.
《Applied Geochemistry》1999,14(3):301-317
A field filtration method for the concentration and separation of suspended particulate matter (SPM) from freshwater systems for subsequent determination of major elements (Si, Al, Ca, Fe, Mn, Mg, Na, K, P, Ti and S) is validated with respect to precision and bias. The validation comprises the whole procedure including filtration, sample digestion and instrumental analysis. The method includes two digestion procedures (microwave acid digestion and alkali fusion) in combination with inductively coupled plasma atomic emission spectrometry (ICP–AES). Total concentrations of the elements have been determined in suspended particulate matter from lake and river water with low levels of suspended solids (<2 mg l−1 DW), and a wide range of element concentrations. The precision of the method including filtration, digestion and instrumental determination ranges between 10 and 14% RSD for most elements on a dry weight basis. Non-detectable concentrations of some elements are reported due to small differences between blank filter levels and the amounts of elements present on the filters after sampling. The calculated sums of main inorganic components, expressed as oxides, ranges between 94.0 and 98.0% ash weight. The method limits of detection range between 3 and 100 μg, as estimated from the blank filter samples. These detection limits are 3–1000 times higher compared to the corresponding instrumental (ICP–AES) limits of detection.A better knowledge of the mechanisms of filter clogging in sampling of suspended matter is important in order to extend the applicability of the method. For the sample types investigated in this study, the amount of inorganic material in the suspended particulate matter (SPM) seems to be the most important factor controlling the maximum volume of filterable water, and Fe is presumably the most important clogging regulating parameter in the group of elements included in the inorganic matter.A critical evaluation of the indirect method of calculating concentrations in SPM as the difference between unfiltered-digested and filtered subsamples is also included. 相似文献
20.
Dominik Weiss William ShotykJack Rieley Susan PageMarlies Gloor Steve ReeseAntonio Martinez-Cortizas 《Geochimica et cosmochimica acta》2002,66(13):2307-2323
Biogeochemical processes in a forested tropical peat deposit and its record of past atmospheric dust deposition were assessed using the vertical distribution of lithophilic and plant essential elements in a dated core profile from Borneo, SE Asia. Peat formation started ∼22,120 14C yr before present (BP), and Ca/Mg mass ratios of the solid peat and very low ash contents indicate a strongly ombrotrophic character throughout the deposit, implying that most of the inorganic fraction has been supplied exclusively by atmospheric inputs. Concentration profiles of Mn, Sr, and Ca suggest a very minor influence of chemical diagenesis in the underlying sediments. Silicon, Ca, Mg, P, S, and K show a strong and extended zone of enrichment in the top 200 cm of the profile, indicating that biological accumulation mechanisms are much more extensive than in temperate peat bogs.In the lower core sections, where the element distribution is dominated solely by past atmospheric deposition, average Al/Ti ratios are similar to the upper continental crust (UCC), whereas Fe is slightly enriched and Si is strongly depleted: this condition favors highly weathered tropical soil dust as the main inorganic mineral source. Significant correlation of Al, Fe, Si, S, Ca, and Ti with the lithophilic elements Y and Zr suggests that the distribution of these elements is controlled by sources of atmospheric mineral dust. The Ca/Mg, Ca/K, and Mg/K ratios of the collected rainwater samples are similar to the global average of continental rainwater and suggest a continental character for the site. This is supported by the similarity of the average concentration of Br, Mg, Ca, and S to that in temperate continental and maritime bogs in Switzerland and Scotland.The concentration profiles of Si, Fe, Al, and Ti show distinct peaks within the profile, implying enhanced dust deposition, reduced rates of peat accumulation, or possibly both owing to climatic changes during the Holocene. Enhanced dust deposition between ∼10,830 and 9060 14C yr BP is tentatively interpreted as a Younger Dryas-like event with dust fluxes of ∼10.8 mg/m2/yr. The variations in Al/Ti and Fe/Ti profiles suggest that mineral dust sources have been changing constantly during the Holocene, with local sources being dominant between ∼7820 and 9500 14C yr BP and long-range transport (derived most likely from China) being important during the late Pleistocene and early Holocene and from ∼7820 14C yr BP to the present. 相似文献