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1.
For a period of 2 a, pore water composition in a heavily contaminated river floodplain soil was monitored in situ. Pore water samples were collected 12 times over all seasons in a profile ranging from aerobic to sulphidic redox conditions, and As, Cd, Cr, Cu, Pb, Zn, Mn, Fe, Ca, Cl, SO4, DOC, IOC and pH were determined. The variability of pH, IOC, DOC and Ca was found to be rather small during the year and within the profile (rsd < 0.04, 0.16, 0.24 and 0.22, respectively). The temporal variability of the metal and As concentrations was small, too, whereas changes with depth were distinct. Under sulphidic conditions, concentrations were below 1 μg L−1 (Cd, Cu, Pb) or 10 μg L−1 (Zn, As). The data set was compared with results from a geochemical model that was fully parameterised from literature data and included equilibrium speciation, sorption and mineral dissolution. The general pattern of the solid–solution partitioning of Cd, Cu, Zn and As in the profile was predicted well by mechanistic geochemical modelling on the basis of solid phase composition. Metals strongly bound to organic matter such as Cd and Cu were predicted better than metals mainly present within a mineral. Detailed information regarding the presence of colloidal Fe and Mn in pore water might improve the prediction of the solid–solution partitioning of a number of metals. The study also indicates that the chemical behaviour of Pb is still not understood sufficiently.  相似文献   

2.
Monthly sampling of slightly alkaline arsenic-rich stream in the Mokrsko gold deposit revealed seasonal variations in dissolved Zn, Cu, As and Mo. Concentrations of trace metal cations (Zn, Cu) increased as much as 330 and 178%, respectively, from minimum mean values at autumn to maximum mean values at spring. In contrast, concentrations of trace element oxyanions (As, Mo) revealed opposite seasonal pattern with increase to 189% (As) and 123% (Mo) during summer–autumn, indicating that in-stream biogeochemical process(es) played the main role in controlling the seasonal variations of these trace elements. The trace elements were mainly scavenged by low crystalline Mn oxyhydroxide and Fe oxyhydroxide (ferrihydrite). Results are consistent with sorption and coprecipitation processes controlling seasonal variations of dissolved Zn and Cu, while As and Mo dynamics appear linked to Mn redox reactions. The sorption processes and Mn redox processes are attributed to the changes of pH and oxic/anoxic conditions on the surface of oxyhydroxides, respectively, which are themselves controlled by the balance between photosynthesis and respiration. Under the geochemical conditions of the stream, inferred Mn redox reactions can only be explained by microbial activity.  相似文献   

3.
We sampled two box-core sediments from the slope of the eastern South Korea Plateau (SKP) in the East Sea (Sea of Japan) at water depths of 1400 and 1700 m. Two chemical fractions of extractable (hydroxylamine/acetic acid) and residual rare earth elements (REEs) together with Al, Ca, Fe, Mg, Mn, P, S, As, Mo, and U were analyzed to assess the post-depositional redistribution of REEs. Extractable Fe and Mn are noticeably abundant in the oxic topmost sediment layer (<3 cm). However, some trace elements (e.g., S, As, Mo, U) are more abundant at depth, where redox conditions are different. Analysis of upper continental crust (UCC)-normalized (La/Gd)UCC, (La/Yb)UCC, and (Ce/Ce*)UCC revealed that the extractable REE is characterized by middle REE (MREE) enrichment and a positive cerium (Ce) anomaly, different from the case of the residual fraction which shows slight enrichment in light REEs (LREEs) with no Ce anomaly. The extractable MREEs seem to have been incorporated into high-Mg calcite during reductive dissolution of Fe oxyhydroxides. In the top sediment layer, the positive Ce anomaly is attributed to Ce oxide, which can be mobilized in deeper oxygen-poor environments and redistributed in the sediment column. In addition, differential concentrations of Ce and other LREEs in pore water appear to result in variable (Ce/Ce*)UCC ratios in the extractable fraction at depth.  相似文献   

4.
《Applied Geochemistry》1998,13(3):359-368
Studies on the speciation (particulate, colloidal, anionic and cationic forms) of trace metals (Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, Zn) in the water column and in pore waters of the Gotland Deep following the 1993/94 salt-water inflows showed dramatic changes in the total “dissolved” metal concentrations and in the ratios between different metal species in the freshly re-oxygenated waters below 125 m. Changes in concentrations were greatest for those metals for which the solubility differs with the redox state (Fe, Mn, Co) but were also noted for those metals which form insoluble sulphides (Cd, Pb, Cu, Zn) and/or stable complexes with natural ligands (Cu). Pore water data from segmented surface muds (0–200 mm) indicated that significant redox and related metal speciation changes took place in the surface sediments only a few weeks after the inflow of the oxygenated sea water into the Gotland Deep.  相似文献   

5.
This study reports on the mobility and retention of trace elements in cassiterite tailings at the inactive Jumna mill, tropical north Queensland. Since the 1980s, the uncapped tailings have developed laterally discontinuous Fe-rich hardpans, which are located in the higher parts of gently sloping tailings masses and at the top (<50 cm) of the tailings piles. Hardpan-cemented tailings comprise thin layers (typically ∼0.2–2 mm thick) of HFO (hydrous ferric oxides) and sulfate efflorescences cementing tailings grains. In comparison to the tailings, the hardpan-cemented tailings contain significantly higher median As, Ca, Cd, Co, Cu, Fe, In, Mn, Mo, Stotal, Th, U, Y and Zn values. Partial leaching studies of tailings and pond water analyses indicate that wetting and acidification of Fe-cemented tailings removes significant proportions of trace elements into pore and surface waters. Tin shows no mobility due to the presence of weathering-resistant cassiterite (SnO2) and, As and Pb display limited mobility possibly due to their coprecipitation with jarosite-type phases and HFO materials at the top of the tailings profile. By contrast, the trace elements Cd, Ce, Cu, La, Ni, Pb, U and Zn display the greatest mobility, possibly due to their incorporation in soluble sulfate efflorescences and sorption onto mineral and HFO surfaces. Hence, the Fe-rich hardpans do not protect the sulfidic tailings from further oxidation nor do they cause permanent sequestration of trace elements.  相似文献   

6.
The Mokrsko Stream in the central Czech Republic is an oxic and slightly alkaline stream that drains a natural As geochemical anomaly. Although long-term monitoring has characterized the general seasonal trends in trace element concentrations (i.e., As, Mo, Cu, Zn) in this stream, little is known about solubility controls and sorption processes that influence diel cycles in trace element concentrations. Trace elements (including As species, Cu, Mn, Mo, Pb and Sb) and other parameters were monitored over two 24-h periods in unfiltered and filtered (0.1 μm) samples collected in August 2010 and June 2011. Copper and Pb were predominantly (>92% of the mass) associated with the particulate fraction (>0.1 μm). Arsenic, Mo and Sb were predominantly (>88% of the mass) in the “dissolved” (<0.1 μm) form. Particulate-associated elements displayed up to a factor of 13 differences between minimum and maximum concentrations, most likely due to increased streamflow related to rainfall events. Dissolved concentrations of the trace metal cations (Cu, Fe, Mn and Pb) were consistently low and displayed no diel trends. Dissolved As(V), Mo and Sb varied on a diel cycle, with increased concentrations (up to 36%) during the late afternoon and decreased concentrations during the nighttime. Diel trends in trace anionic elements are explained by temperature-dependent sorption, as the diel changes in pH during base flow were very small (0.07 std. units). Very low concentrations of As(III), which have been shown to vary in a diel cycle, were attributed to enhanced hydraulic exchange with As(III)-rich hyporheic water during rainfall events.  相似文献   

7.
The sediments of the Port Camargue marina (South of France) are highly polluted by Cu and As (Briant et al., 2013). The dynamics of these pollutants in pore waters was investigated using redox tracers (sulfides, Fe, Mn, U, Mo) to better constrain the redox conditions.In summer, pore water profiles showed a steep redox gradient in the top 24 cm with the reduction of Fe and Mn oxy-hydroxides at the sediment water interface (SWI) and of sulfate immediately below. Below a depth of 24 cm, the Fe, Mn, Mo and U profiles in pore waters reflected Fe and Mn reducing conditions and, unlike in the overlying levels, sulfidic conditions were not observed. This unusual redox zonation was attributed to the occurrence of two distinct sediment layers: an upper layer comprising muddy organic-rich sediments underlain by a layer of relatively sandy and organic-poor sediments. The sandy sediments were in place before the building of the marina, whereas the muddy layer was deposited later. In the muddy layer, large quantities of Fe and Mo were removed in summer linked to the formation of insoluble sulfide phases. Mn, which can adsorb on Fe-sulfides or precipitate with carbonates, was also removed from pore waters. Uranium was removed probably through reduction and adsorption onto particles. In winter, in the absence of detectable pore water sulfides, removal of Mo was moderate compared to summer.Cu was released into solution at the sediment water interface but was efficiently trapped by the muddy layer, probably by precipitation with sulfides. Due to efficient trapping, today the Cu sediment profile reflects the increase in its use as a biocide in antifouling paints over the last 40 years.In the sandy layer, Fe, Mn, Mo and As were released into solution and diffused toward the top of the profile. They precipitated at the boundary between the muddy and sandy layers. This precipitation accounts for the high (75 μg g−1) As concentrations measured in the sediments at a depth of 24 cm.  相似文献   

8.
The paper presents data on the specifics of the distributions of chemical elements in natural waters of the Kola North depending on the landscape–geochemical characteristics of the water catchment areas and aerotechnogenic pollution. The territory is subdivided into seven zones with different dominant rock types and typical landscapes. Lakes in the Kola region generally contain elevated concentrations of Cu, Ni, Co, Cr, V, Mo, U, Sb, Bi, Al, Fe, Mn, Sr, Li, Rb, Pb, Zn, Cd, La, and Ce. The waters of lakes in the influence zones of Cu–Ni mines are enriched in La, Ce, Sm, Gd, Pr, and Nd. In waterlogged landscapes, waters are enriched in certain trace elements because of their migration with humic acids. Technogenic acidic precipitation is proved to result in leaching of several elements, first of all Cd, Zn, and As (as well as other elements contained in rocks composing the water catchment areas) and their transfer into the waters.  相似文献   

9.
Historically, a significant level of mining activity has taken place in the batholite-related metalogenic enclave of Linares (Jaén province, Spain), associated with Pb–Ag, Cu, Zn and Fe sulphides and Ba sulphate mineralization, though mining here has now been abandoned. Additionally, the area features a significant amount of urban, industrial and agricultural activities. These considerations, taken together, explain the need to assess the levels of concentration of trace elements and to determine their relationship with geogenic and anthropogenic factors. For geochemical characterisation of the soil, the region has been divided into 126 grid squares with an area of 1 km2. For each grid square, 32 trace elements have been analysed. Elemental concentrations of Cu, Pb, Zn, As and Mn have been included in statistical analyses. According to the reference levels established by the Regional Government (Junta de Andalucía), soils in a large part of the study area require amendment applications. The comparison of the mean content for each grid square with the reference levels reveals a significant degree of contamination of the soil by Cu (719 mg kg−1), Pb (22,964 mg kg−1) and As (100 mg kg−1) in those grid squares affected by metallurgic activities. By means of factor analysis, four scores have been identified which together account for 80% of the variance observed. The first score is highly correlated with the logarithms of the variables Fe, Th, La, Ti, Al, Na, K, Zr, Y, Nb, Be and Sc. It is a “natural” factor that indicates the type of soil matrix (fundamentally granites and, to a lesser degree, Triassic materials). The second score shows high correlation with the logarithms of the variables Mo, Cu, Pb, Zn, Ag, Co, Mn, As, Cd, Sb, Ba, W and Sn, and is the “metallization” factor related to the mineralization that has been exploited. The third score is mainly determined by the logarithms of the variables Sr, Ca and Mg. This is a “natural” factor that indicates a type of carbonate soil matrix (Miocene). Finally, the fourth factor groups the logarithms of the variables Ni, V and Cr, elements that are associated with the combustion of fossil fuels. Analysis of the patterns of each of the factors identified enabled achieving a global characterisation of the study area. Cluster analysis of the observations showed there to be five clusters relating to the grid squares, differentiated by lithologies and degrees of contamination. These clusters are used to determine the background of granite and to calculate the anomalous load.  相似文献   

10.
Large sections of the Abitibi volcanic belt of Archean age are covered by thick glacial and glacio-lacustrine overburden. To increase our knowledge of the geology and the economic potential of the basement, approximately 5000 ground-water samples were collected from wells, springs and drill holes over an area of about 20 000 km2. Samples were collected at intervals varying from 150 to 500 m in settled areas. They were analysed for: Cu, Zn, Pb, Ni, Co, Cd, Cr, Mn, Fe, Mo, Hg, As, U, Na, K, Ca, Mg, Li, F, and Cl− and pH.Several types of regional and local geochemical patterns were identified. However, since the apparent dispersion distance of trace elements from a point source is usually less than 1 km in ground waters, the local zones of geochemical activity having an area less than 15 km2 are considered of greatest interest for exploration. The large regional patterns and geochemical complexes which consist of clusters of grouped, overlapping, and superimposed regional and local patterns are presumed to be related to particular geological or metallogenic contexts.The elements with the highest frequency of occurrence in the 240 identified local zones of geochemical activity are As, Ni and U which occur in more than 30% of these zones; they are closely followed by the groups Co, Cu, Mo and Zn, Hg, Pb, F− which occur respectively in more than 25% and 20% of the zones. Element associations in these zones can be broken down into three major groups: the trace metals (Cu, Zn, Pb, Co, Cd, Mo), the major and associated elements (Na, K, Ca, Mg, Li, F−, Cl−) and the elements As, U and Ni which occur with elements of either of the first two groups.Ground-water samples were also collected in 21 mines. The results of this study suggest that the best indicator elements for base metal deposits are As, Mo and F, whereas As, Ni, F− or Cl− and Mn are the best indicators of gold deposits.The results of the ground-water survey have identified numerous new areas to explore. Anomalous concentrations of at least two of the best indicators occur in more than 33% of the 240 local zones of geochemical activity.  相似文献   

11.
The characterization of trace elements in terms of their apportionment among dissolved, macromolecular, nano- and micro-particulate phases in the water column of the Great Salt Lake carries implications for the potential entry of toxins into the food web of the lake. Samples from the anoxic deep and oxic shallow brine layers of the lake were fractionated using asymmetric flow field-flow fractionation (AF4). The associated trace elements were measured via online collision cell inductively-coupled plasma mass spectrometry (CC-ICP-MS). Results showed that of the total (dissolved + particulate) trace element mass, the percent associated with particulates varied from negligible (e.g. Sb), to greater than 50% (e.g. Al, Fe, Pb). Elements such as Cu, Zn, Mn, Co, Au, Hg, and U were associated with nanoparticles, as well as being present as dissolved species. Particulate-associated trace elements were predominantly associated with particulates larger than 450 nm in size. Among the smaller nanoparticulates (<450 nm), some trace elements (Ni, Zn, Au and Pb) showed higher percent mass (associated with nanoparticles) in the 0.9–7.5 nm size range relative to the 10–250 nm size range. The apparent nanoparticle size distributions were similar between the two brine layers; whereas, important differences in elemental associations to nanoparticles were discerned between the two layers. Elements such as Zn, Cu, Pb and Mo showed increasing signal intensities from oxic shallow to anoxic deep brine, suggesting the formation of sulfide nanoparticles, although this may also reflect association with dissolved organic matter. Aluminum and Fe showed greatly increased concentration with depth and equivalent size distributions that differed from those of Zn, Cu, Pb and Mo. Other elements (e.g. Mn, Ni, and Co) showed no significant change in signal intensity with depth. Arsenic was associated with <2 nm nanoparticles, and showed no increase in concentration with depth, possibly indicating dissolved arsenite. Mercury was associated with <2 nm nanoparticles, and showed greatly increased concentration with depth, possibly indicating association with dissolved organic matter.  相似文献   

12.
Sedimentary pyrites in black shales contain abundant trace elements that provide information on the chemistry of the seawater at the time of sedimentation. This study focuses on the Barney Creek Formation (~ 1640 Ma) in the McArthur Basin in the Northern Territory of Australia, which is host to one of the world's largest SEDEX Zn-Pb-Ag deposits, and several smaller deposits. Fine-grained sedimentary pyrite has been sampled from three drill holes through the Barney Creek Formation at various distances from SEDEX mineralisation. Samples were selected through the stratigraphy of each hole and analysed by LA-ICPMS for a suite of 14 trace elements. The data show that sedimentary pyrite at the base of the Barney Creek Formation, closest (within 1 km) to SEDEX mineralisation, is strongly enriched in Zn and Tl by one to two orders of magnitude compared to the global average for sedimentary pyrite. In contrast sedimentary pyrite from the hole furthest from SEDEX mineralisation (~ 60 km) contains mean Zn and Tl values equal to, or less than, the global average. Based on the three drill hole pyrite data sets it is concluded that trace elements that are contributed to the basin during hydrothermal exhalation, and adsorbed into contemporaneous sedimentary pyrite, are principally Zn, Tl, Cu, Pb, Ag and As. In contrast, trace elements that are adsorbed into sedimentary pyrite from background seawater are principally Mo, Ni, Co, Se and As. These differences have enabled the development of a SEDEX fertility diagram for sedimentary basins, based on the composition of sedimentary pyrite, that distinguish high Zn, but barren shales, from high zinc SEDEX-related shales. In parallel with the increase in Zn and Tl in sedimentary pyrite approaching mineralisation there is a decrease in Ni, Co and Mo. This means that the ratios Zn/Ni and Tl/Co are particularly good pyrite vectors to SEDEX mineralisation in the McArthur Basin, varying over 4 to 6 orders of magnitude from barren shales to mineralised shales. It is speculated that the reason for the reverse relationship between Ni, Co and Zn, Tl may be caused by hydrothermal exhalations into the water column that effect the ion-exchange pyrite surface complexation processes that alter the uptake of these elements into sedimentary pyrite.Another important conclusion of this study is that hydrothermal exhalations into a sedimentary basin may affect the redox sensitive trace element chemistry of sedimentary pyrite and therefore the trace element chemistry of pyritic black shales. Nickel, Co and Mo all decrease in proximity to hydrothermal vents that form SEDEX deposits, whereas Zn, Tl and Pb increase. Selenium and bismuth are the only redox sensitive trace elements that appear to be unaffected by hydrothermal activity in the McArthur Basin. This has implications on how trace element concentrations of black shales and pyrite are used to reflect past global ocean chemistry.  相似文献   

13.
The elemental composition of high temperature ash (750°C) and forms of S were studied in 25 coal seams from the Escucha Formation (Middle Albian) in the Teruel Mining District, northeast Spain. The principal analytical method was ICP-MS, but ICP-ES was also used in the determination of some trace elements. The analytical data show wide ranges of trace element cotnents among the coal seams studied, even in the vertical profile of a single coal seam. These wide ranges of the trace element concentrations are attributed to both syngenetic and epigenetic processes.When a comparison was made between the average trace element contents of the Teruel Mining District coals, and those of the average content in worldwide coals, the Teruel coals show slightly higher concentrations of Be and U, and lower concentrations of Ba, Cd, Mn, Pb, Sr and Zr. Further, three main groups of trace elements were differentiated on the basis of the inorganic/organic association: (1) trace elements with inorganic affinity; Ba, Ce, Co, Cr, La, Mn, Ni, Rb and Zr. Between these, Ba, Ce, Cr and Rb show a well defined correlation with the clay mineral content, and Co and Ni with pyritic-S content; (2) trace elements with an intermediate (mixed) affinity; As, Cd, Cu, Dy, Er, Eu, Gd, Ge, Ho, Lu, Mo, Nd, Pb, Pr, Sb, Sm, Sr, Tb, Th, Tm, U, Yb and Zn. In this group, As, Cd, Cu, Ge, Mo, Th, U and Zn show a weak trend associated with the mineral matter and Sr with the organic matter; and (3) Be shows an organic affinity. The high mineral matter content (21.3% HTA) of the Teruel coals may account for the great number of elements with inorganic affinity. This classification represents a general trend, but the results show that the affinities of some trace elements (e.g. As, Sb and Zn) may vary from one coal seam to another in the Teruel Mining District.  相似文献   

14.
To evaluate trace element soil contamination, geochemical baseline contents and reference values need to be established. Pedo-geochemical baseline levels of trace elements in 72 soil samples of 24 soil profiles from the Mediterranean, Castilla La Mancha, are assessed and soil quality reference values are calculated. Reference value contents (in mg kg?1) were: Sc 50.8; V 123.2; Cr 113.4; Co 20.8; Ni 42.6; Cu 27.0; Zn 86.5; Ga 26.7; Ge 1.3; As 16.7; Se 1.4; Br 20.1; Rb 234.7; Sr 1868.4; Y 38.3; Zr 413.1; Nb 18.7; Mo 2.0; Ag 7.8; Cd 4.4; Sn 8.7; Sb 5.7; I 25.4; Cs 14.2; Ba 1049.3; La 348.4; Ce 97.9; Nd 40.1; Sm 10.7; Yb 4.2; Hf 10.0; Ta 4.0; W 5.5; Tl 2.3; Pb 44.2; Bi 2.2; Th 21.6; U 10.3. The contents obtained for some elements are below or close to the detection limit: Co, Ge, Se, Mo, Ag, Cd, Sb, Yb, Hf, Ta, W, Tl and Bi. The element content ranges (the maximum value minus the minimum value) are: Sc 55.0, V 196.0, Cr 346.0, Co 64.4, Ni 188.7, Cu 49.5, Zn 102.3, Ga 28.7, Ge 1.5, As 26.4, Se 0.9, Br 33.0 Rb 432.7, Sr 3372.6, Y 39.8, Zr 523.2, Nb 59.7, Mo 3.9, Ag 10.1, Cd 1.8, Sn 75.2, Sb 9.9, I 68.0, Cs 17.6, Ba 1394.9, La 51.3, Ce 93.5, Nd 52.5, Sm 11.2, Yb 4.2, Hf 11.3, Ta 6.3, W 5.2, Tl 2.1, Pb 96.4, Bi 3.0, Th 24.4, U 16.4 (in mg kg?1). The spatial distribution of the elements was affected mainly by the nature of the bedrock and by pedological processes. The upper limit of expected background variation for each trace element in the soil is documented, as is its range as a criterion for evaluating which sites may require decontamination.  相似文献   

15.
A test comparing concentrations of 57 chemical elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Er, Eu, Fe, Ga, Gd, Ge, Hf, Ho, I, K, La, Li, Lu, Mg, Mn, Mo, Na, Nb, Nd, Ni, Pb, Pr, Rb, Sb, Se, Sm, Sn, Sr, Ta, Tb, Te, Th, Ti, Tl, Tm, U, V, W, Y, Yb, Zn and Zr) determined by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) in 294 samples of the same bottled water (predominantly mineral water) sold in the European Union in glass and PET bottles demonstrates significant (Wilcoxon rank sum test, α = 0.05) differences in median concentrations for Sb, Ce, Pb, Al, Zr, Ti, Th, La, Pr, Fe, Zn, Nd, Sn, Cr, Tb, Er, Gd, Bi, Sm, Y, Lu, Dy, Yb, Tm, Nb and Cu. Antimony has a 21× higher median value in bottled water when sold in PET bottles (0.33 vs. 0.016 μg/L). Glass contaminates the water with Ce (19× higher than in PET bottles), Pb (14×), Al (7×), Zr (7×), Ti, Th (5×), La (5×), Pr, Fe, Zn, Nd, Sn, Cr, Tb (2×), Er, Gd, Bi, Sm, Y, Lu, Yb, Tm, Nb and Cu (1.4×). Testing an additional 136 bottles of the same water sold in green and clear glass bottles demonstrates an important influence of colour, the water sold in green glass shows significantly higher concentrations in Cr (7.3×, 1.0 vs. 0.14 μg/L), Th (1.9×), La, Zr, Nd, Ce (1.6×), Pr, Nb, Ti, Fe (1.3×), Co (1.3×) and Er (1.1×).  相似文献   

16.
The Okchon black shale in Korea provides a typical example of natural geological materials enriched with potentially toxic elements. The Chung-Joo, Duk-Pyung, Geum-Kwan, I-Won, Bo-Eun and Chu-Bu areas are underlain by these black shales and slates of the Guryongsan Formation or the Changri Formation, which are parts of the Okchon Group in the central part of the southern Korean Peninsula. In order to investigate the enrichment levels and dispersion patterns of potentially toxic elements in the rock–soil–plant system, environmental geochemical surveys were undertaken in the above six study areas in the Okchon Zone. After appropriate preparation, rock and soil samples were analyzed for potentially toxic elements by instrumental neutron activation analysis (INAA) and inductively coupled plasma atomic emission spectrometry (ICP-AES), and plant samples by atomic absorption spectrometry (AAS). In particular, Ba, Cd, Mo, V and U in Okchon black shales are highly enriched, and their mean concentrations are significantly higher than those in black slates. These elements are geochemically associated, and might be enriched simultaneously. The highest mean concentrations of 42.0 μg g−1 As, 2100 μg g−1 Ba, 10.9 μg g−1 Cd, 213 μg g−1 Mo, 83 μg g−1 U, 938 μg g−1 V and 394 μg g−1 Zn are found in black shales from the Duk-Pyung area. Mean concentrations of As, Mo and U in soils overlying black shales occurring in the Duk-Pyung area (30 μg g−1 As, 24 μg g−1 Mo and 50 μg g−1 U) and Chu-Bu area (39 μg g−1 As, 15 μg g−1 Mo and 27 μg g−1 U) are higher than the permissible level. Enrichment index values of the six study areas decrease in the order of Duk-Pyung > Chu-Bu > Bo-Eun > Chung-Joo > Geum-Kwan = I-Won areas. Relationships between trace element concentrations in soils and plants are significantly correlated, and the biological absorption coefficients (BAC) in plants are in the order of Cd > Zn = Cu > Pb, which suggests that Cd is more bioavailable to plants than the other elements. Cadmium concentrations in plant species decrease in the order of chinese cabbage > red pepper > soybean = sesame > rice stalk > corn > rice grain. From the result of sequential extraction analysis of soils, relatively high proportions of Cu, Pb and Zn are present as residual fractions, and that of Cd as non-residual fractions. Cadmium occurs predominantly as exchangeable/water-acid soluble phase in soils, and this is in agreement with the findings of high Cd concentrations in plants.  相似文献   

17.
The La Luna Formation (Maraca section), Maracaibo Basin, was studied by means of V and Ni analysis of the bitumen, total organic carbon (TOC), total sulfur (St), major elements (Si, Al, Fe, Mg, Mn, Ca, Ti, Na, K, P), trace elements (V, Ni, Co, Cr, Cu, and Zn), and electron microprobe analysis (EPMA) of the whole rock, and St, major elements (Si, Al, Fe, Mg, Mn, Ca, Ti, Na, K, P), trace elements (V, Ni, Co, Cr, Cu, Zn, Mo, Ba, U, Th) and rare earth elements (La, Ce, Nd, Sn, Eu, Th, Yb, Lu) of the carbonate-free fraction. The results are discussed based on the organic and inorganic association of trace elements and their use as paleoenvironmental indicators of sedimentation. An association between V and organic matter is suggested by means of correlation between V and Ni vs. TOC, the use of EPMA (whole rock) and V and Ni concentrations (carbonate-free fraction), whereas Ni is found in the organic matter and the sulfide phase. Fe is present as massive and framboidal pyrite, whereas Zn precipitates into a separate phase (sphalerite), and Ni, Cu and, in some cases, Zn, can be found as sulfides associated with pyrite. Concentrations of V and Ni (bitumen), TOC, St, V, Ni, Cr, Cu and Zn (whole rock), U, Th, Mo (carbonate-free fraction) are indicative of changes in the dysoxic sedimentation conditions in the chert layers (TOC, St, V, Ni, Cu and low Zn and V/Cr <4) to euxinic anoxic conditions in the argillaceous limestone (TOC, St, V, Ni, Cu and high Zn and V/Cr >4). In the sequence corresponding to the argillaceous limestone, variations in the concentrations of TOC, St, V, Ni, Zn, Cu and Cr (whole rock) can be observed, also suggesting variable sedimentation conditions. The following is proposed: (i) sedimentation intervals under euxinic conditions associated with high contribution and/or preservation of organic matter, allowing a high concentration level of V and Ni in the organic phase and the accumulation of Cu, Zn and Ni (in a smaller proportion) in the sulfide phase; (ii) sedimentation intervals under anoxic conditions and in the presence of relatively lower H2S, which allowed lower concentrations of V and Ni in the organic phase and higher concentrations of Cu, Zn, and Ni in the sulfide phase. Rare earth elements (REE) concentrations exhibit a marked increase in Ce, Nd, Sm, Eu, Y and Lu for the QM-3 interval, relative to Post-Archean Average Shale (PAAS). REE enrichment in shales has been related to the presence of phosphate minerals such as monazite or apatite. However, these minerals were not detected through XRD or EPMA in the whole rock or in the carbonate-free fraction. The association of REE with organic matter is suggested due to the absence of phosphate minerals, although assessment of these elements require further analysis.  相似文献   

18.
Exogenic contamination is of primary concern for geochemical and biological clean laboratories working with sample sizes at the nanogram or even subpicogram level. Here, we determined sixty trace elements in fifteen different types of gloves from major suppliers world‐wide to evaluate whether gloves could be potential sources of contamination for routine trace element and isotope measurements. We found that all gloves contain some trace elements that can be easily mobilised in significant amounts. In weak acid at room temperature, the tested gloves released up to 17 mg of Zn, more than 1 μg of Mg, Ti, Mn, Fe, Rb, Sr, Zr, Sn, Hf and Pb and between 100 and 1000 ng of Li, Sc, V, Cr, Ni, Cu, Ga, As, Se, Y, Ag, Ba, La, Ce, Nd, Tl and Th. Vinyl gloves released lower quantities of biologically and geologically important elements, with the exception of In and Sn. Isotopic analyses indicate that all gloves share roughly the same Zn isotopic composition (average δ66Zn = +0.10 ± 0.32‰ (2s)). A single contact between glove and labware releases an average of ~ 6 ng of Zn and hence can significantly shift δ66Zn above the precision level when the amount of Zn determined is below 500 ng.  相似文献   

19.
Vertical profiles from the water column, including the maximum turbidity zone (MTZ) to the consolidated sediment were sampled in September 2000 in the freshwater reaches of the Gironde Estuary during a complete neap tide-spring tide cycle. The vertical distributions of dissolved major redox parameters and metals (Mn, Fe, Cd, Cu, V, Co, Ni, Mo, and U) were determined. Reactive particulate metal fractions were also determined from selective leaching. The studied system is characterized by density layers functioning at different time-scales, consisting of two mobile layers, i.e., the liquid (LM) and the soft mud (SM), overlying consolidated sediments (CS). This results in a three-zone diagenetic regime where (1) O2 dynamics are fast enough to show depletion in the rapidly mixed LM sequence (tidal time-scale), (2) denitrification occurs on the weekly time-scale mixing SM sequence, and (3) the Mn, Fe, and sulfate cycling occurs in the CS layer (annual time-scale). The studied trace metals show differential behavior during early diagenesis: (1) Cd, Cu, and V are released into pore water preferentially from organic matter in the SM, (2) Co, Ni, and U are released in the CS from Mn and Fe oxides during reductive dissolution, and (3) Mo from both processes. Transient conditions (i.e., oscillations of redox fronts and reoxidation processes), due to the dynamics of the mobile layers, strongly influence the trace metal distributions as inducing resolubilization (Cd, Cu, and Mo). In the CS, authigenic metal phases accumulate, either by direct precipitation with sulfides (Cu, Cd) or co-precipitation with Fe-sulfides (Mo). Microbially mediated reduction of Fe oxides is proposed to control U removal from pore water by reduction of U(VI) to U(IV) at depth. However, a significant fraction of the trace metals is trapped in the sediment in exchangeable forms, and therefore is susceptible to be mobilized due to resuspension of estuarine sediment during strong river flood periods and/or dredging activities.  相似文献   

20.
The Bell Springs deposit is a bulk-tonnage, low-grade gold deposit, formed in a hot-spring environment, that is hosted by middle Miocene weakly peralkaline, high-silica rhyolite ash flows and rheomorphic tuffs. Ore grade mineralization over about 460 × 460 m was controlled by northeast- and northwest-trending structures. Sixty-nine soil samples collected along a traverse across the Bell Springs deposit, screened into six mesh size fractions, +10, −10+35, −35+80, −80+120, −120+200, and −200, were treated by low-detection-limit acid digestion/organic extraction procedures, and analyzed by ICP or graphite furnace techniques for Au, Ag, As, Bi, Cd, Cu, Ga, Hg, Mo, Pb, Sb, Se, Te, Tl, and Zn. Twenty-five stream-sediment samples were collected from a drainage crossing mineralization and from a nearby tributary. Sediment size fractions of −200 mesh and −10+200 mesh were analyzed by the same procedures used for soils. In addition, analyses of bulk leachable gold via cyanide leach method (BLEG) was done on bulk −10 mesh sediments.Anomalous Au, Ag, As, Sb, and Mo in all soil size fractions revealed the underlying ore. Areas with anomalous Sb and As were about three times larger than areas with anomalous Au and Ag. Analyses of fine-fractions of stream sediments provided the best-defined Au anomalies in drainages. A multi-element factor calculated by multiplying Au, As, Sb, and Mo reinforced anomalous Au in drainages and correlated well with Bell Springs mineralization.  相似文献   

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