南极普里兹湾表层沉积物微量元素分布特征及其物源指示意义

利用电感耦合等离子体质谱仪测定了中国南极科考21~27航次期间获取的普里兹湾表层沉积物中Cu、Pb、Zn、Cd、Cr、Co、Al、Fe、Mn的含量,分析了普里兹湾微量元素的分布特征,结合沉积物粒度分布、生物硅含量,并利用富集系数和主成分分析的方法,探讨了微量元素的物源指示意义。研究结果表明:普里兹湾沉积物中的微量元素含量与南大洋其他海域具有很好的可比性。Cu、Zn、Cr、Co、Fe、Mn含量在陆坡深海区明显高于冰架边缘区和陆架区;Al、Pb含量在冰架边缘区较高;而Cd含量在陆架区相对较高。人类活动对普里兹湾沉积物中的微量元素没有明显的影响,南极大陆岩石风化产物和海洋生物源性沉降是其主要来源。冰架边缘区及陆架破折处P2-9站位的微量元素主要为岩源性输入。陆架区、陆坡深海区的微量元素Cu、Zn、Cr、Co、Fe、Mn明显受到生源性物质输入的影响。而普里兹湾沉积物中Cd则主要来源于硅藻的吸收利用及硅质软泥的富集。     

The geochemical study of fluvio-lacustrine aquifers in the Kathmandu Basin (Nepal) and the implications for the mobilization of arsenic

The geochemical analyses of fluvial-lacustrine aquifer sediments of the Kathmandu Valley have been made as a step in assessing the environment for the mobilization of arsenic in groundwater. Elements measured by X-ray fluorescence (XRF) include 4 major oxides (Fe₂O₃, TiO₂, CaO, P₂O₅) and 14 trace elements (As, Pb, Zn, Cu, Ni, Cr, V, Sr, Y, Nb, Zr, Th, Sc and TS). Elution tests of 15 selected core samples were also carried out to determine the potential leaching of arsenic from the sediments. The XRF results show that average bulk concentrations of the major oxides and trace elements are similar to modern unconsolidated sediments and average upper continental crust. However, the abundance of elements varies with grain size, with higher concentrations in finer-size grades. Variations in elemental abundances within the basin are strongly controlled by sediment facies. The elution tests show that greater amounts of arsenic are generally eluted from the fine sediments, although the rates are variable. The results overall suggest that As concentrations in the bulk sediments are not a controlling factor for elevated As in the Kathmandu Basin groundwater, and the roles of other factors such as redox conditions and organic matter contents are likely to be more significant.     

A critical evaluation of using bulk sediment instead of fine fraction in environmental marine studies, investigated on example of Rijeka harbor, Croatia

This work tested the preferential use of fine (<63 μm) or bulk sediment (<2 mm) in environmental research of marine sediments in the Eastern Adriatic. Fine fraction sediment containing silt and clay (<63 μm), predominating in the studied area, was examined to evaluate past and present anthropogenic inputs and to test our hypothesis that investigation of bulk sediment should be preferred. Following aqua regia digestion, chemical analyses of 58 elements were performed by ICP/OES, ICP-MS and cold vapor AAS, and statistical analysis was performed. The concentrations of the majority of the analyzed elements increased with age of the sediment, except for Ag and Sn, which had higher concentrations in recent sediments. The previous main sources of metal contamination in Rijeka harbor were now abandoned municipal-sewage outflow and oil refinery, and continuing harbor activities and antifouling paint use. All activities except of antifouling paint use have been decreasing significantly. Anomalies of selected elements were determined by the box-plot method. More anomalies were found in the bulk sediment than in the fine fraction. Results of Q-modality clustering and factor analysis in the fine fraction almost correlate with that applied on bulk sediments. Thus, it can be said that the differences between the element distribution in the bulk and fine fraction are not statistically significant. Our conclusion is that analysis of bulk marine sediment gives a better insight into the state of pollution and supports previous recommendations to use bulk sediment as a chosen media for environmental studies.     

Geochemistry of the accumulation of metals in bottom sediments at the Razdol’naya River-Amur Bay marginal filter: I. Pelite fraction

The composition of clay minerals in the subcolloid fraction from the uppermost layer of bottom sediments in the northern part of Amur Bay was determined by X-ray powder diffraction analysis, and the enrichment of 33 elements in the subcolloid and pelite fractions of the surface deposits from a number of sites at the marginal filter of the Razdol’naya River was studied by ICP-MS.Fe, U, and chalcophile elements are contained in the highest concentrations in sediments from all sampling sites within the filter. The bottom sediments are not enriched in trace, alkali, and alkali-earth elements. The maximum concentrations of chemical elements were found in deposits from the brackish part of the marginal filter, perhaps, because of the formation of Fe and Mn (Al) hydroxides. Bottom sediment at the boundary between the brackish and marine parts of the filter contain the lowest concentrations of the examined elements.     

Trace metal and radionuclide pollution in marine sediments of the Aegean Sea (Izmir Bay and Didim)

To determine radioactivity and trace metal levels, surface sediments were collected from two important areas (?zmir Bay and Didim) in the Aegean Sea region of Turkey, and were analyzed for concentrations of ²¹⁰Po, ²¹⁰Pb and trace metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn). The average ²¹⁰Po and ²¹⁰Pb massic activities in sediments varied in the range of 24 ± 5 to 126 ± 6 Bq kg^?1 dry wt. and 18 ± 3 to 59 ± 4 Bq kg^?1 dry wt., respectively. Izmir Bay exhibited the highest polonium activities in sediments, likely due to specific sedimentation processes and other sediment characteristics. The trace metal results showed that the Izmir Bay is facing trace metal pollution. The metal concentrations in sediment samples are low compared to those from the other neighboring marine environments.     

Geochemical characteristics of elements in suspended sediments in the Huanghe (Yellow) River

Eighteen suspended sediment samples were collected along the Huanghe River main stem from upper reaches on the Qinghai-Tibet Plateau (Tibet Plateau) to the entrance at the Bo Hai Bay and at confluences of its tributaries, during the first summer flood in 1980. Major elements such as Si, Al, Fe, Ca, Mg, K, Na, and trace elements such as As, Ba, Cd, Ce, Co, Cr, Cu, Ga, Hg, Li, Mn, Mo, Ni, P, Pb, Se, Sn, Sr, Ti, V, Zn and humus were examined. Variations in composition of suspended sediments also were studied. Three major types of sediment composition were observed. The controlling factor for the variation is parent rocks, though climate and vegetation played an active role. Correlation coefficients, cluster analysis, and enrichment factors were calculated to study the geochemical characteristics of the sediments. Mg, Na and Fe were the only ones subject to considerable leaching, whereas Se, Cd, Zn were significantly accumulated, indicating a low intensity of weathering.     

Geogene Versus Anthropogene Origin of Trace Metals in Sediments in Cua Luc Estuary and Ha Long Bay, Vietnam

In the present study, the geochemistry of 49 surficial-bed and 101 core sediment samples is investigated to clarify the origin of trace metals in the Cua Luc Estuary and Ha Long Bay, which is a famous World Natural Heritage Site in Vietnam. Moreover, the potential mobility of trace metals is also assessed and their relationship with reference elements (Al, Fe, and Ca) and organic matter is established in order to make recommendations for sediment management and monitor future pollution. Generally, trace metals display higher concentrations in Ha Long Bay compared to the Cua Luc Estuary. However, this is controlled by the distribution of the fine (clay?+?silt) fraction, and hence the concentrations of Al, Fe, Ca, and organic matter (OM). The comparison of concentrations of trace metals (normalized towards Al) between the surficial sediments and the subsurface core sediments based on ¹³⁷Cs datings indicates that almost all surficial-sediment data fall inside or deviate slightly from the 95 % prediction interval of a background regression line. In addition, as determined by a Community Bureau of Reference three-step extraction, trace metals mainly dominate in the residual fraction (assumed to relate to crystal lattice of primary and secondary minerals), and this fraction does not change much in recent sediment layers. Therefore, trace metals are supposed to be derived from natural bio/geochemical processes and are characterized by a low potential mobility. Consequently, the established linear regression relationships of trace metal vs. Al or multiple regression relationships of trace metal vs. multi-elements (Al, Fe, Ca, and OM) are useful for the prediction of background levels of trace metals in sediments in future pollution monitoring and assessment programs.     

Sediment origin and budget in Sepetiba Bay (Brazil) - an approach based on multielemental analysis

 Sediment origin and transport were determined in a shallow 447 km² coastal lagoon in Brazil, using the distribution of major elements in bottom and suspended sediments. Applying multivariate analysis, the sum of normalized concentrations of Ti, Fe, and Al in sediments was selected to trace the terrigenous influence in bottom sediments, whereas Ca, Si, and K were used as indicators of marine influence. Sepetiba Bay bottom sediments are dominated by up to 80% terrigenous inputs. The open bay sediments are enriched in P, Mg, K, and Ca because of the intensive water column primary production. The inner bay forms an independent circulation cell with a predominance of terrigenous sediments. The results suggest a long residence time for particles in the bay, demonstrated by the magnitude of resuspension flux compared to the total sediment input to the bay. Received: 29 May 1996 · Accepted: 17 December 1996     

海相沉积物碳酸盐相中微量元素的分析方法研究

海相沉积物中自生沉积碳酸盐相的微量元素携带极为丰富的原始地质信息,然而海相沉积物中碳酸盐相的测定还没有建立统一的标准方法.本文以修正的Tessier七步提取流程为基础,以电感耦合等离子体质谱法(ICP-MS)为检测手段,针对海相沉积物碳酸盐相组分中V、Cr、Co、Ni、Sr五种微量元素建立了分级提取方法.实验以海相沉积物样品和标准物质作为参考样品,对比了NaAc和EDTA提取碳酸盐相的效果.结果表明,NaAc不能完全提取出沉积物碳酸盐相中的微量元素;EDTA可以较好地提取自生海相沉积物碳酸盐相中的微量元素,但是由于其络合能力太强还会提取有机物结合态的金属元素.本研究确定的分级提取方法是:首先用中性盐NaC1去除离子交换态,然后用提取专一性较强的焦磷酸钠(pH =10)去除有机态,再用EDTA提取仅自生海相沉积物的碳酸盐相.方法精密度(RSD)均＜5％,各元素的检出限在0.5～ 4.3 ng/g之间,回收率在88.0％ ～ 101.6％之间,方法的选择性和稳定性能够满足地球化学样品形态分析的要求.     

The role of zooplankton fecal pellets in the sedimentation of polycyclic aromatic hydrocarbons in Dabob Bay,Washington

Polycyclic aromatic hydrocarbon (PAH) compositions were determined in plankton, sediment-trap-collected particulate material and sediment cores from Dabob Bay using a high performance liquid Chromatographie (HPLC)/fluorescence technique. The annual flux of individual PAH measured in a series of sediment traps was compared with the flux of corresponding compounds determined from ²¹⁰Pb dated bottom sediments. Systematic seasonal variations in the fluxes and concentrations of PAH, Al and organic carbon in the trap-collected particulates and seasonally collected plankton were also investigated to determine whether or not PAH are associated with either terrestrial or marine-derived materials.Concentrations of all PAH studied increased tenfold within the last 80–100 yr of sediment deposition, except for perylene which displayed a reasonably constant concentration profile. This suggests at least two sources contribute to the observed sedimentary PAH compositions in Dabob Bay, i.e., anthropogenic combustion and a natural source. Plankton and sediment trap-collected particulates contained PAH mixtures qualitatively similar to underlying surface sediments. Microscopic examination indicated fecal pellets were the major form of particulate material in the sediment traps. The fecal pellets collected in the sediment trap time series quantitatively account for essentially 100% of the PAH fluxes measured in the ²¹⁰Pb dated sediments, implying Zooplankton fecal pellets control the removal of PAH to Dabob Bay sediments. These measurements provide clear evidence that the PAH studied are not produced after sediment deposition. The observed seasonal covariations of PAH and Al in both sediment trap and plankton samples further indicate that PAH originate from terrestrially-based sources, are introduced into the marine environment by runoff and erosion or atmospheric deposition and are not produced by marine plankton.     

Geological and geochemical examination of arsenic contamination in groundwater in the Holocene Terai Basin, Nepal

Geological and geochemical study has been carried out to investigate arsenic contamination in groundwater in Nawalparasi, the western Terai district of Nepal. The work carried out includes analyses of core sediments, provenance study by rare earth elements analyses, ¹⁴C dating, and water analyses. Results showed that distribution of the major and trace elements are not homogeneous in different grain size sediments. Geochemical characteristics and sediment assemblages of the arsenic contaminated (Nawalparasi) and uncontaminated (Bhairahawa) area have been compared. Geochemical compositions of sediments from both the areas are similar; however, water chemistry and sedimentary facies vary significantly. Extraction test of sediment samples showed significant leaching of arsenic and iron. Chemical reduction and contribution from organic matter could be a plausible explanation for the arsenic release in groundwater from the Terai sediments.     

Geochemistry of hydrothermally influenced sediments off Methana (western Hellenic volcanic arc)

Surface sediment samples from near-shore shallow water as well as deeper water locations N and NE of the island of Methana were investigated geochemically. Shallow water samples from Thiafi Bay reveal up to 38-fold enrichment of As, associated with elevated contents of Sb, Fe and Zn. Deeper water samples NE of Methana show moderate Mn enrichment accompanied with elevated trace metal concentrations of As and, in some samples, Cd and Cu. In an area, where small mounds of possible hydrothermal origin were observed on the sea floor, fine-grained Fe-rich sediment was sampled with enrichment of typical hydrothermal trace elements As, P and Sb. Element enrichment in the investigated areas off Methana corresponds in terms of absolute concentrations and element suite to comparable hydrothermally influenced sediments from other locations of the Hellenic volcanic arc. The region between Methana peninsula and Aegina Island is not marked by vigorous hydrothermal activity, but localised enrichments of Fe and/or Mn, As, Sb as well as associated trace elements typically found in hydrothermally influenced sediments were identified.     

Distributions of uronic acids and O-methyl sugars in sinking and sedimentary particles in two coastal marine environments

Although recent research has indicated that bacteria may contribute an important fraction of biochemical residues in terrestrial and marine environments, it is difficult for geochemists to identify contributions from these ubiquitous and biochemically diverse organisms. Previous studies have suggested uronic acids and O-methyl sugars may be useful indicators of microbial abundance and activity, but have been limited primarily to analyses of a small number of isolated samples. We report here comparative distributions of O-methyl sugars, uronic acids, and aldoses in sediment trap material and sediments from Dabob Bay, WA and nearby Saanich Inlet, BC, where temporal and spatial trends may be used together with well-established patterns in other biochemicals to identify bacterial contributions against the background of other carbohydrate sources.O-methyl sugars and uronic acids were important contributors to the overall flux and burial of polysaccharide material in Dabob Bay and Saanich Inlet, composing ≤12 wt% of the total carbohydrate yields from sediment trap and sediment samples. O-methyl sugars accounted for an average of 5% of the carbohydrate yields from sediment trap materials and sediments, but were found rarely and only in low abundance in vascular plant tissues, phytoplankton, and kelp. In contrast, uronic acids were abundant products of sediment trap material and sediments, as well as vascular plant tissues, where in some cases they predominated among all carbohydrates. Uronic acid abundance in sediment trap material averaged 3% and ranged to >6% of total carbohydrate yields.The persistence of total minor sugar yields in water column collections from Dabob Bay throughout the seasonal cycle indicated they had a primary source that was not directly related to plankton bloom cycles nor pulsed inputs of vascular plant remains. Subsurface maxima in total minor sugar yields (and several individual components) within sediment cores from both sites indicate in situ sedimentary sources. Taken together, the observed environmental distributions strongly suggest that the minor sugar abundances in Dabob Bay and Saanich Inlet were controlled by in situ microbial production.     

Temporal and spatial evolution of surface sediments characteristics in the Dagu River estuary and their dynamic response mechanism

Based on the 39 surface sediment samples collected in the flood season and the dry season in 2012 respectively and the measured hydrological data in October 2012, the sediment grain size characteristics has been analyzed and the response mechanism of surface sediments to estuarine hydrodynamics was revealed by calculating the range of waves and tidal currents. The results show that: (1) The grain size of the surface sediment samples decreased gradually from land to sea in the flood season. The fine sediment was redistributed under marine hydrodynamics in the dry season and the sediments showed coarser tendency ingeneral; (2) tidal current stirring sediment was very obvious in Dagu River estuary area, and wave stirring sediments mainly occurred in the tidal flat area and estuary sand bar area; (3) in the flood season, surface sediment sat the estuary were transported towards south and southeast. In the dry season, surface sediments were transported towards southwest at the north area of Jiaozhou Bay Bridge, and sediments were transported towards northeast area at the south of Jiaozhou Bay Bridge.     

Carbohydrate sources in a coastal marine environment

Individual neutral sugars in sediments, sediment trap materials and major biological sources of a coastal marine environment (Dabob Bay, Washington State) were analyzed by capillary gas chromatography of equilibrated isomeric mixtures. Plankton, bacteria, and vascular plant tissues of different types yielded reproducible and biochemically consistent compositional patterns. These patterns, when expressed in simple parameters, allowed distinctions between marine and terrestrial carbohydrate sources as well as among the major different types of vascular plant tissues. Plankton and bacteria, due to their compositional diversity, were not further distinguishable by carbohydrate compositions alone. Carbohydrate compositions of Dabob Bay sediments and sediment trap materials, interpreted using source-indicator parameters, indicate a predominantly marine origin with increased relative input of terrestrially-derived carbohydrates in winter periods of low phytoplankton productivity. Both plankton and grasses are indicated as major carbohydrate sources during spring. Glucose yield enhancement factors, determined by comparative acid pretreatments, confirm the general predominance of α-cellulose-poor marine polysaccharides and increased levels of α-cellulose-rich vascular plant remains in winter sediment trap samples.     

Authigenic associations between selected rare earth elements and trace metals in lacustrine sediments

Surficial sediment samples were collected at 47 stations in Little Traverse Bay, Lake Michigan, to determine the geochemical associations between certain rare earth elements (REE's) and trace metals. Each sample was analyzed for carbonate carbon, organic carbon, grain size, and the elements Al, Ca, Ce, Co, Cr, Eu, Fe, Hf, La, and Mn. Two distinct Ce subpopulatins were identified by graphical analysis, and an R-mode factor analysis was applied to data from the “enriched” Ce subpopulation (18 samples). Results show that the REE's and trace metals are primarily enriched in the authigenic phase of these sediments. Partial correlation analyses indicate that the REE's are primarily associated with hydrous Fe oxides relative to organic matter in this phase. The ratio of Ce/La concentrations increased markedly from the bay margins to the central trough of the bay, indicating that Ce, similar to Fe, exhibits a variable oxidation state in the authigenic phase of nearshore fine-grained sediments. The results of the present study suggest that the REE's and trace metals behave coherently in the authigenic phase of recent lacustrine sediments, and the REE's may be useful as geochemical tracers to differentiate between trace metal enrichments in surface sediments as a result of diagenesis and pollution loadings.     

Spatial distribution of major and trace elements in shallow reservoir sediments: an example from Lake Waco, Texas

 Sediment geochemistry of a shallow (6-m average) reservoir (Lake Waco) was evaluated for the spatial distribution of major and trace elements. Sixty bottom and core samples along a 21-km transect within the reservoir, 18 overbank sediment samples, and 8 rock types in the drainage area were collected and analyzed for major (Al, Ca, Fe) and trace elements (As, Ba, Cr, Cu, Hg, Mn, Ni, Pb, Sr, V, Zn). Elemental concentrations in the reservoir sediments closely correspond to concentrations in the regional rocks and represent a mixture of overbank sediment composition of the tributaries. Elemental concentrations were statistically regressed against Al concentrations in order to establish regional baseline levels and thereby distinguish natural from anthropogenic sources. Spatial geochemical trends, considered in terms of element-to-Al ratio versus V-to-Al ratio, relate to the natural and anthropogenic sources contributing to the elemental concentrations. The spatial elemental distribution in the reservoir, which receive sediments from two mineralogically contrasting basins, reflect textural and mineralogical transition within the reservoir and suggest a progressive mixing of sediment from the tributaries. The spatial elemental distribution and sediment texture suggest that the sediment-source, which determines the sediment-type, has a greater influence on the major- and trace-element distributions in shallow reservoir sediments than bathymetry. Received: 25 September 1997 · Accepted: 3 February 1998     

Environmental change of the fluvial-estuary system in relation to Arase Dam removal of the Yatsushiro tidal flat,SW Kyushu,Japan

Chemical composition of 24 elements for sediments and suspended solids, water parameters and the diatoms from Yatsushiro Bay tidal flat, Kuma River, and Arase Dam have been determined to examine changes from 2002 to 2013. In 2002, sediment delivered to the bay by the Kuma River was restricted by the Arase Dam; however, in April 2010 two gates were opened and also repeated seasonal flushing allowing resumption of natural sediment transport. Bulk chemical composition of the tidal flat sediments has changed since 2002, with marked decreases in concentrations of As, Zn, Pb and total sulfur. Decreased heavy metal contents in 2012 and 2013 for bay sediments after opening the dam and repeated flushing is attributed to dilution by previously impounded quartz and feldspar. Restoration of natural sediment transport by opening the dam and repeated flushing has thus brought about a recovery in the Yatsushiro marine environment.     

The use of hydroxyacids as geochemical indicators

The distributions of hydroxyacids in a variety of Recent and ancient sediments have been determined by gas chromatography-mass spectrometry. A lacustrine sediment (Rostherne Mere, U.K.) and two marine situations (Cariaco Trench, Black Sea) were analyzed as examples of Recent depositional environments. β-hydroxyacids occurred in all of the Recent sediments, consistent with their presumed microbial origin, whereas di- and trihydroxyacids were present in the sediments with a significant higher plant input (Black Sea and Rostherne Mere sediments). The two ancient (Eocene) sediments examined, viz. the Greene River (U.S.) and Messel (Germany) oil-shales, contained only trace amounts of hydroxyacids. These results provide evidence that hydroxyacids are in general not well preserved over geological time.     

福建三沙湾海洋沉积物中重金属和过渡元素来源分析

依据2004年的调查资料,分析了三沙湾海洋沉积物的重金属和过渡元素的含量,对过渡元素的分布特征、过渡元素与重金属的相关性进行了系统研究,并探讨了其环境和物源意义。结果表明:沉积物中的Cd、Cu、Hg、Pb与Fe2O3有很好的相关性。三沙湾周边的山脉富含金属矿石,这种矿石含有Fe2O3、Ni和Mn等多种元素,矿石经过暴雨冲刷和江河径流将多种元素带入海洋沉积物中,使得Cu和Zn都有较高含量,高于中国浅海沉积物含量,高于福建省土壤背景值,说明这种现象主要是天然来源占多数,人为输入占少量。