Trace analysis of Zn-doped compound semiconductor material by resonant ionization mass spectrometry

An experimental setup and the procedure for the laser resonant ionization mass spectrometry (RIMS) have been described. Both an optical spectrum and a mass spectum have been shown. The detection limit that can be reached by using this procedure has been estimated.

TRACE ANALYSIS AT A MERCAPTOACETIC ACID-MODIFIED ELECTRODE

The strong chelating ability of mercaptoacetic acid for certain metal ions is exploited for a new; kind of voltammetric sensor. Specifically, a glassy carbon electrode (GCE) surface was covalently covered br; mercaptoacetic acid. The preparation of mercap

DETERMINATION OF TRACE AMOUNT OF 14 RARE-EARTH IMPURITIES IN HIGH-PURITY YTTRIUM-OXIDE WITH ICP-AES

A method of analysis of high purity yttrium oxide with ICP-AES was described with emphasis on the study of Y_2O_3 matrix effects. The results showed that the line intensities of ana]ytes decreased with the increase of Y_2O_3 concentration in solution because of following factors. (1) The presence of matrix resulted in the decrease of the amount of analytes reaching ICP. (2) Matrix Y_2O_3 entering the plasma decreased the excitation temperature of the plasma and depressed the ionization of analytes in the pl...

Quantitatively distinguishing sediments from the Yangtze River and the Yellow River using delta Eu-N-I REEs pound plot

Sediment samples were collected from the lower channel of the Yangtze River and the Yellow River and the contents of rare earth elements (REEs) were measured. In addition, some historical REEs data were collected from published literatures. Based on the delta Eu-N-I REEs pound plot, a clear boundary was found between the sediments from the two rivers. The boundary can be described as an orthogonal polynomial equation by ordinary linear regression with sediments from the Yangtze River located above the curve and sediments from the Yellow River located below the curve. To validate this method, the REEs contents of sediments collected from the estuaries of the Yangtze River and the Yellow River were measured. In addition, the REEs data of sediment Core 255 from the Yangtze River and Core YA01 from the Yellow River were collected. Results show that the samples from the Yangtze River estuary and Core 255 almost are above the curve and most samples from the Yellow River estuary and Core YA01 are below the curve in the delta Eu-N-I REEs pound plot. The plot and the regression equation can be used to distinguish sediments from the Yangtze River and the Yellow River intuitively and quantitatively, and to trace the sediment provenance of the eastern seas of China. The difference between the sediments from two rivers in the delta Eu-N-I REEs pound plot is caused by different mineral compositions and regional climate patterns of the source areas. The relationship between delta Eu-N and I REEs pound is changed little during the transport from the source area to the river, and from river to the sea. Thus the original information on mineral compositions and climate of the source area was preserved.

The contribution of trace elements from seawater to chimneys: a case study of the native sulfur chimneys in the sea area off Kueishantao, northeast of Taiwan Island

Hydrothermal fluid containing abundant matter erupts from seafloor, meets ambient cold seawater and forms chimneys. So the main matter origins of chimneys are seawater and matter which are taken by hydrothermal fluid from deep reservoir. However, because of seawater's little contribution to the forming of chimneys, it is usually covered by the abundant matter which is taken by hydrothermal fluid. Therefore, chimneys formed in ordinary deep seawater hydrothermal activity, containing complex elements, cannot be used to study the seawater's contribution to their formation. While the native sulfur chimneys, formed by hydrothermal activity near the sea area off Kueishantao, are single sulfur composition (over 99%), and within chimneys distinct layers are seen. Different layers were sampled for trace element determination, with Inductively Coupled Plasma Mass Spectrometry (ICP-MS). By analyzing the data, we consider C-layer (secondary inner-layer) as the framework layer of the chimney which formed early (Fig. 4), and its trace elements derive from hydrothermal fluid. While the trace elements within A, B, D layers have undergone later alteration. A, B layers are affected by seawater and D layer by hydrothermal fluid. The increase of trace elements of A and B layers was calculated using C layer as background. Based on the known typical volume of chimneys of the near sea area off Kueishantao, we calculated the volume of seawater that contributed trace element to chimneys formation to be about 6.37 x 10(4) L. This simple quantified estimate may help us better understand the seafloor hydrothermal activity and chimneys.

Trace element composition of peridotites from the southern Mariana forearc: Insights into the geochemical effects of serpentinization and/or seafloor weathering

Peridotites from the southern Mariana forearc were sampled on the landward trench slope of the Izu-Bonin-Mariana (IBM) subduction zone by dredging. These mantle wedge peridotites underwent hydration by fluid derived from a dehydrated descending slab, and later interacted with seawater after emplacement at or near the seafloor. This study investigates how these two different rock-fluid interaction processes influenced trace element distribution in the southern Mariana forearc peridotites. We measured trace element concentrations of peridotites from the southern Mariana forearc. The southern Mariana forearc peridotites are characterized by a distinct seawater-like REE pattern with an obvious negative Ce anomaly, and La shows good correlation with other REEs (except Ce). In addition, there is a great enrichment of U, Pb, Sr and Li elements, which show a distinct positive anomaly relative to adjacent elements in the multi-element diagram. For the seawater-like REE pattern, we infer that REEs are mainly influenced by seawater during peridotite-seawater interactions after their emplacement at or near the seafloor, by serpentinization or by marine weathering. Furthermore, the anomalous behavior of Ce, compared with other rare earth elements in these samples, may indicate that they have undergone reactions involving Ce (IV) when the peridotites interacted with seawater. Positive U, Pb, Sr and Li anomalies are inferred to be related to seawater and/or fluids released during dehydration of the subducting slab.

Element enrichment and U-series isotopic characteristics of the hydrothermal sulfides at Jade site in the Okinawa Trough

The geochemical and U-series isotopic characteristics of hydrothermal sulfide samples from the Jade site (127A degrees 04.5'E, 27A degrees 15'N, water depth 1300-1450 m) at Jade site in the Okinawa Trough were analyzed. In the hydrothermal sulfide samples bearing sulfate (samples HOK1 and HOK2), the LREEs are relatively enriched. All the hydrothermal sulfide samples except HOK1 belong to Zn-rich hydrothermal sulfide. In comparison with Zn-rich hydrothermal sulfides from other fields, the contents of Zn, Pb, Ag, Cd, Au and Hg are higher, the contents of Fe, Al, Cr, Co, Ni, Sr, Te, Cs, Ti and U lower, and the Pb-210 radioactivity ratios and Pb-210/Pb ratios very low. In the hydrothermal sulfide mainly composed of sphalerite, the correlations between rare elements Hf and U, and Hf and Mn as well as that between dispersive elements Ga and Zn, are strongly positive; also the contents of Au and Ag are related to Fe-sulfide, because the low temperature promotes enrichment of Au and Ag. Meanwhile, the positive correlations between Fe and Bi and between Zn and Cd are not affected by the change of mineral assemblage. Based on the Pb-210/Pb ratios of hydrothermal sulfide samples (3.99x10(-5)-5.42x10(-5)), their U isotopic composition (U-238 content 1.15-2.53 ppm, U-238 activity 1.07-1.87 dpm/g, U-234 activity 1.15-2.09 dpm/g and U-234/U-238 ratio 1.07-1.14) and their Th-232 and Th-230 contents are at base level, and the chronological age of hydrothermal sulfide at Jade site in the Okinawa Trough is between 200 and 2000 yr.

Sediment provenance and province of the southern Yellow Sea: Evidence from light mineral

The distribution for percent content of light mineral is divided in detail to emphasize distributional trends of higher and lower contents by using 222 samples of light mineral in the southern Yellow Sea. 5 mineral provinces are divided, and they are I-north mineral province of the southern Yellow Sea, the sediment dominantly derived from the Yellow River; II-mixed mineral province, the sediment derived from both the Yellow River and Yangtze River; III-middle mineral province, the sediment derived mainly from the Yellow River and a part of sediment derived from Yangtze River; IV-province east of Yangtze River mouth, the sediment derived dominantly from Yangtze River; and V south mineral province, sediment was affected by relict sediment and modern sediment of Yangtze River. In this paper, the assemblage of dominant mineral and diagnostic mineral for the five provinces are discerned.

Clay mineral distributions in the southern Yellow Sea and their significance

To better understand the characteristics of the clay minerals in the southern Yellow Sea, the X-ray quantitative determinations have been carried out for the surface samples obtained from the Yellow Sea. With newly compiled clay mineral synoptic maps, the depositional processes were described for four main clay minerals (illite, chlorite, kaolinite and smectite). The analysis shows that most clay minerals are of terrigenous source with the Huanghe River acting as the major sediment supplier. Besides, the source of muddy sediments in the Yellow Sea was also discussed. As for the central Yellow Sea mud (CYSM), the sediments in its northern part mainly come from the Huanghe River, and those in the rest are of multi-origin. Very similarly, a large amount of sediments in the northern part of the southeastern Yellow Sea Mud (SEYSM) derive from the Keum River and Yeong-san River, while those in the southern part are of multi-origin.

Mineral provinces and matter provenance of the surficial sediments in the western Philippine Sea: implication for modern sedimentation in West Pacific marginal basin

The characteristics and distribution patterns of detrital minerals (0.063 similar to 0.125 mm) in marine sediments provide a significant indicator for the identification of the origin of sediment. The detrital mineral composition of 219 surface sediment samples was analysed to identify the distribution of sediments within the western Philippine Sea. The area can be divided into three mineral provinces: ( 1) province east of the Philippine Trench, the detrital minerals in this province are mainly composed of calcareous or siliceous organisms, with the addition of volcanogenic minerals from an adjacent island arc; (II) middle mineral province, clastic minerals including feldspar, quartz and colorless volcanic glass, sourced from seamounts with intermediate-acid volcanic rock, or erupting intermediate-acid volcano; (III) province west of the Palau-Kyushii Ridge, the matter provenance within this province is complex; the small quantity of feldspar and quartz may be sourced from seamounts or erupting volcano with intermediate - acid composition, with a component of volcanic scoria sourced from a volcano erupting on the Palau-Kyushu Ridge. it is suggested that, ( I) Biogenic debris of the study area is closely related to water depth, with the amount of biogenic debris controlled by carbonate lysocline. (2) Volcaniclastic matter derived from the adjacent island are can be entrained by oceanic currents and transported towards the abyssal basin over a short distance. The weathering products of volcanic rocks of the submarine plateau ( e. g. I Benham Plateau) and adjacent ridges provide an important source of detrital sedimentation, and the influence scope of them is constrained by the intensity of submarine weathering. (3) Terrigenous sediments from the continent of Asia and the adjacent Philippine island arc have little influence on the sedimentation of this study area, and the felsic mineral component is probably sourced from volcanic seamounts of intermediate-acid composition.

Major element, trace element, and Sr, Nd and Pb isotope studies of Cenozoic basalts from the South China Sea

The whole rock K-Ar ages of basalts from the South China Sea basin vary from 3.8 to 7.9 Ma, which suggest that intra-plate volcanism after the cessation of spreading of the South China Sea (SCS) is comparable to that in adjacent regions around the SCS, i.e., Leiqiong Peninsula, northern margin of the SCS, Indochina block, and so on. Based on detailed petrographic studies, we selected many fresh basaltic rocks and measured their major element, trace element, and Sr-Nd-Pb isotope compositions. Geochemical characteristics of major element and trace element show that these basaltic rocks belong to alkali basalt magma series, and are similar to OIB-type basalt. The extent of partial melting of mantle rock in source region is very low, and magma may experience crystallization differentiation and cumulation during the ascent to or storing in the high-level magma chamber. Sr-Nd-Pb isotopic data of these basaltic rocks imply an inhomogeneous mantle below the South China Sea. The nature of magma origin has a two end-member mixing model, one is EM2 (Enriched Mantle 2) which may be originated from mantle plume, the other is DMM (Depleted MORB Mantle). Pb isotopic characteristics show the Dupal anomaly in the South China Sea, and combined with newly found Dupal anomaly at Gakkel ridge in Arctic Ocean, this implies that Dupal anomaly is not only limited to South Hemisphere. In variation diagrams among Sr, Nd and Pb, the origin nature of mantle below the SCS is similar to those below Leiqiong peninsula, northern margin of the SCS and Indochina peninsula, and is different from those below north and northeast China. This study provides geochemical constraints on Hainan mantle plume.

Mineral provinces and material provenance of the surficial sediments near the Zhongsha Islands in the South China Sea

Characteristics and distribution patterns of elastic minerals (0.063 similar to 0.125 mm) in bottom sediments represent a significant indicator for the identification of the origin of sediment. One hundred and fourteen surface sediment samples, which were collected from the area near the Zhongsha Islands in the South China Sea, were analysed to identify the mineral suites and their distributions in the study area. The area can be divided into three mineral provinces: ( I) a province of biogenic minerals, which mainly originate from the Zhongsha Atoll; ( H) a province of volcanogenic minerals, which are mainly derived from local basaltic seamounts and small-scale volcanoes that are probably erupting, with some influences from the island-are volcanic region around the South China Sea; and (II) a mixed mineral province whose material source includes biogenic minerals, volcanogenic minerals and terrigenous minerals; the last province can be subdivided into a mixed mineral sub-province of the northeastern part of the study area, in which terrigenous minerals are mainly derived from China's Mainland and do not exceed 17 degrees N, and a mixed mineral sub-province of the southeastern part of the study area, in which terrigenous minerals are derived from Kalimantan and Indochina Peninsula and might be further transported into the deep sea basin through submarine canyons.

Formation of Fe-oxyhydroxides from the East Pacific Rise near latitude 13 degrees N: Evidence from mineralogical and geochemical data

The mineralogical and geochemical characteristics of Fe-oxyhydroxide samples from one dredge station (long. 103 degrees 54.48'W, lat. 12 degrees 42.30'N, water depth 2655 m) on the East Pacific Rise near lat 13 degrees N were analyzed by XRD, ICP-AES, and ICP-MS. Most Fe-oxyhydroxides are amorphous, with a few sphalerite microlites. In comparison with Fe-oxyhydroxides from other fields, the variable ranges in the chemical composition of Fe-oxyhydroxide samples are very narrow; their Fe, Si, and Mn contents were 39.90%, 8.92%, and 1.59%, respectively; they have high Cu (0.88%-1.85%) and Co (65x10(-6)-704x10(-6)) contents, and contain Co+Cu+Zn+Ni > 1.01%. The trace-element (As, Co, Ni, Cu, Zn, Ba, Sr) and major-element (Fe, Ca, Al, Mg) contents of these samples are in the range of hydrothermal sulfide from the East Pacific Rise near 13 degrees N, reflecting that this type of Fe-oxyhydroxide constitutes a secondary oxidation product of hydrothermal sulfide. The Fe-oxyhydroxide samples from one dredge station on the East Pacific Rise near 13 degrees N are lower in Sigma REE (5.44x10(-6)-17.01x10(-6)), with a distinct negative Ce anomaly (0.12-0.28). The Fe-oxyhydroxide samples have similar chondrite-normalized rare-earth-element (REE) patterns to that of seawater, and they are very different from the REE composition characteristics of hydrothermal plume particles and hydrothermal fluids, showing that the REEs of Fe-oxyhydroxide are a major constituent of seawater and that the Fe-oxyhydroxides can become a sink of REE from seawater. The quick settling of hydrothermal plume particles resulted in the lower REE content and higher Mn content of these Fe-oxyhydroxides, which are captured in part of the V and P from seawater by adsorption. The Fe-oxyhydroxides from one dredge station on the East Pacific Rise near 13 degrees N were formed by secondary oxidation in a low temperature, oxygenated environment. In comparison with the elemental (Zn, Cd, Pb, Fe, Co, Cu) average content of hydrothermal sulfide samples from the East Pacific Rise near 13 degrees N, the Zn, Cd, and Pb contents of the Fe-oxyhydroxides are lower, and their Fe, Co, and Cu contents are higher.

Evolution and variability of the East Asian summer monsoon during the Pliocene: Evidence from clay mineral records of the South China Sea

The Late Pliocene is thought to be characterized by the simultaneous intensification of both the East Asian winter monsoon (EAWM) and East Asian summer monsoon (EASM). However, the evolution of the EASM during the Pliocene remains still controversial and only little is known about the dynamics of the EASM during the Pliocene on orbital time scales. Here we use clay mineral assemblages in sediments from Ocean Drilling Program (ODP) Site 1143 in the southern South China Sea (SCS) to obtain proxy records of past changes in the EASM climate during the Pliocene. Provenance analysis suggests that illite, chlorite and kaolinite originated mainly from the Mekong River drainage area. Smectite was derived mainly from the Indonesian islands. The kaolinite/illite ratio and the chemical index of alteration (CIA) of siliciclastic sediments allowed us to reconstruct the history of chemical weathering and physical erosion of the Mekong River drainage area and thus, the evolution of,the EASM during the Pliocene. Our clay minerals proxy data suggests a stronger EASM during the Early Pliocene than during the Late Pliocene. We propose that the long-term evolution of the EASM has been driven by global cooling rather than the uplift of the Tibetan Plateau. Spectral analysis of kaolinite/ illite ratio displays a set of strong periodicities at 100 ka, 30 ka, 28 ka, 25 ka, and 22 ka. with no clear obliquityrelated signal. Our study suggests that the Pliocene EASM intensity on orbital time scales is not only controlled by the Northern Hemisphere summer insolation, but also strongly influenced by equatorial Pacific ENSO-like ocean atmosphere dynamics. (C) 2010 Elsevier B.V. All rights reserved.