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1.
《Applied Geochemistry》2006,21(9):1593-1612
Sediments, mosses and algae, collected from lake catchments of the Larsemann Hills, East Antarctica, were analysed to establish baseline levels of trace metals (Ag, As, Cd, Co, Cr, Cu, Ni, Sb, Pb, Se, V and Zn), and to quantify the extent of trace metal pollution in the area. Both impacted and non-impacted sites were included in the study. Four different leaching solutions (1 M MgCl2, 1 M CH3COONH4, 1 M NH4NO3, and 0.3 N HCl) were tested on the fine fraction (<63 μm) of the sediments to extract the mobile fraction of trace metals derived from human impact and from weathering of basement lithologies. Results of these tests indicate that dilute HCl partly dissolves primary minerals present in the sediment, thus leading to an overestimate of the mobile trace metal fraction. Concentrations of trace metals released using the other 3 procedures indicate negligible levels of anthropogenic contribution to the trace metal budget. Data derived from this study and a thorough characterisation of the site allowed the authors to define natural baseline levels of trace metals in sediments, mosses and algae, and their spatial variability across the area. The results show that, with a few notable exceptions, human activities at the research stations have contributed negligible levels (lower than natural variability) of trace metals to the Larsemann Hills ecosystem. This study further demonstrates that anthropogenic sources of trace metals can be correctly identified and quantified only if natural baselines, their variability, and processes controlling the mobility of trace metals in the ecosystem, have been fully characterised.  相似文献   

2.
Fresh water lakes are found in basement rock basins in the Larsemann Hills, East Antarctica, during the summer months. These lakes constitute a relatively simple natural laboratory to investigate the effects of recent and well-documented anthropogenic impact on a “pristine” environment. Larsemann Hills freshwaters have extremely low salinity (typically <1‰), and contain very low concentrations of trace elements of environmental significance such as Pb, U, and Zn. Typical Pb concentrations range from less than 5 ppt to 250 ppt. Although trace metal concentrations appear to be higher in lakes situated in the vicinity of stations, they are consistently lower (by several orders of magnitude, for some elements) than Standard International Drinking Water Guidelines. The chemistry of the lake waters is dominated by sea-spray input. Consequently, it is primarily a function of geographical factors, such as distance from the shore and exposure to winds. Shallow-level groundwater and surface water also contribute to the lake chemistry. No evidence was found for contamination from global air circulation. Although contamination resulting from activities at the research stations is generally near or below detection levels, very low levels of trace metal anthropogenic contamination were found in the vicinity of some research stations. Received: 13 November 1998 · Revised: 23 March 1999 Accepted: 12 April 1999  相似文献   

3.
The presence of glacial sediments across the Rauer Group indicates that the East Antarctic ice sheet formerly covered the entire archipelago and has since retreated at least 15 km from its maximum extent. The degree of weathering of these glacial sediments suggests that ice retreat from this maximum position occurred sometime during the latter half of the last glacial cycle. Following this phase of retreat, the ice sheet margin has not expanded more than ∼ 1 km seaward of its present position. This pattern of ice sheet change matches that recorded in Vestfold Hills, providing further evidence that the diminutive Marine Isotope Stage 2 ice sheet advance in the nearby Larsemann Hills may have been influenced by local factors rather than a regional ice-sheet response to climate and sea-level change.  相似文献   

4.
This study reports a multi-parameter geochemical investigation in water and sediments of a shallow hyper-eutrophic urban freshwater coastal lake, Zeekoevlei, in South Africa. Zeekoevlei receives a greater fraction of dissolved major and trace elements from natural sources (e.g., chemical weathering and sea salt). Fertilizers, agricultural wastes, raw sewage effluents and road runoff in contrast, constitute the predominant anthropogenic sources, which supply As, Cd, Cu, Pb and Zn in this lake. The overall low dissolved metal load results from negligible industrial pollution, high pH and elevated metal uptake by phytoplankton. However, the surface sediments are highly polluted with Pb, Cd and Zn. Wind-induced sediment resuspension results in increased particulate and dissolved element concentrations in bottom waters. Low C/N ratio (10) indicates primarily an algal source for the sedimentary organic matter. Variation in sedimentary organic C content with depth indicates a change in primary productivity in response to historical events (e.g., seepage from wastewater treatment plant, dredging and urbanization). Primary productivity controls the enrichment of most of the metals in sediments, and elevated productivity with higher accumulation of planktonic debris (and siltation) results in increased element concentration in surface and deeper sediments. Aluminium, Fe and/or Mn oxy-hydroxides, clay minerals and calcareous sediments also play an important role in adsorbing metals in Zeekoevlei sediments.  相似文献   

5.
Open pit mining of base-metals from the high-sulfidation epithermal type deposit of Kirki (Thrace, NE Greece) resulted in the formation of an acid pit lake by infilling of the open cast by rain and draining waters after mine closure. The high toxic metals content of the ore, the limited buffering capacity of host rocks and the direct exposure of the ore zone to weathering result in an intense release of metals into the pit lake. The acidic and oxidative pit lake waters show high concentrations of trace metals. A mineral precipitate, covering the floor of the pit lake, comprises secondary anglesite, several species of the jarosite-group, rozenite, melanterite, wroewolfeite, gypsum, bukovskyite, beaverite, scorodite and minor goethite. The mineral precipitate presents a significant heavy metal content indicating effective removal of metals from the acid waters. Compared to other pit lakes in high-sulfidation type deposits it has a higher metal load, consistent with the mineralogy and grade of ore in pit walls.  相似文献   

6.
Dissolved trace elements and heavy metals of waters and sediments in the ten shallow lakes in the middle and lower reaches of the Yangtze River region were determined to identify their composition and spatial distribution, and to assess the extent of their environmentally detrimental effects by comparison with water and sediment quality guidelines. Results indicated that As and Pb were the main pollutants in lake waters and Mn and Hg the potential ones, while As, Cu and Pb were the main pollutants in lake sediments. Their spatial distribution indicated that Daye Lake was seriously polluted by metals, which was corroborated by cluster analysis. Higher concentrations of trace elements have been found in lakes downstream of the Yangtze River delta, and higher concentrations of metals have been recorded in sediments of upstream lakes, suggesting that metals in water were more sensitive to anthropogenic activities and that metals in sediment were mainly controlled by minerals. Correlation analyses demonstrated that there were stronger associations among metals in lake sediments than those in lake waters, and their good relationships suggested the common sources. Further research on the subject will help develop water quality management with the aim of restoring shallow lakes in the Yangtze River.  相似文献   

7.
Eighteen sediment samples and six water-column samples were collected in a small (6 km2), coastal embayment (Port Jefferson Harbor, New York) to define a high-resolution spatial distribution of metals and to elucidate sources of contaminants to the harbor. Sediment metal (Ag, Cu, Fe, Ni, Pb, V, and Zn) concentrations varied widely, reflecting differences in sediment grain size, with higher metal concentrations located in the fine-grained inner harbor sediments. Calculated enrichment factors for these sediments show that Ag, Pb, Cu, and Zn are elevated relative to both crustal abundances and their respective abundances in sediments in central Long Island Sound. Metal concentrations were 1.2 to 10 fold greater in water from the inner harbor compared to water from Long Island Sound collected outside the mouth of the harbor. Spatial variations in trace metals in surface waters within the bay parallel the spatial variations of trace metals in sediments within the harbor. Elevated water-column metal concentrations appear to be partially derived from a combination of diagenetic remobilization from contaminated sediments (e.g., Ag) and anthropogenic sources (e.g., Cu and Zn) within the southern portions of the harbor. Although the National Status and Trends Program had reported previously that sediment metal concentrations in Port Jefferson Harbor were low, the results of this study show sediment metals have high spatial variability and are enriched in the inner harbor sediments at levels comparable to more urbanized western north shore Long Island harbors.  相似文献   

8.
In this study, the total concentration and speciation of trace elements (As, Cr, Cu, Cd, Pb, Zn, and Ni), in sediments of the Maharlu saline Lake, SW Iran are investigated. Comparison with sediment quality guidelines, calculation of the enrichment factors, and trace metal profiles in the Khoshk River inflow point indicate that Maharlu Lake is in the threat of contamination, especially with respect to Ni and Cd. Sequential extraction analysis reveals that elemental speciation in this lake is strongly affected by oxidizing condition of the lake water. The studied elements (except Cr) are mainly associated with oxide phases, as a result of prevailing oxidizing conditions of the lake and also probably due to the source of elements. The ratio of metals in mobile fractions to sum of fractions in lake sediments is very low. However, metal ratios (except for Cr) in mobile fractions are much higher in surface sediments, indicating the impact of anthropogenic loading of trace metals in the recent years.  相似文献   

9.
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。  相似文献   

10.
The Late Quaternary climate history of the Larsemann Hills has been reconstructed using siliceous microfossils (diatoms, chrysophytes and silicoflagellates) in sediment cores extracted from three isolation lakes. Results show that the western peninsula, Stornes, and offshore islands were ice‐covered between 30 000 yr BP and 13 500 cal. yr BP. From 13 500 cal. yr BP (shortly after the Antarctic Cold Reversal) the coastal lakes of the Larsemann Hills were deglaciated and biogenic sedimentation commenced. Between 13 500 and 11 500 cal. yr BP conditions were warmer and wetter than during the preceding glacial period, but still colder than today. From 11 500 to 9500 cal. yr BP there is evidence for wet and warm conditions, which probably is related to the early Holocene climate optimum, recorded in Antarctic ice cores. Between 9500 and 7400 cal. yr BP dry and cold conditions are inferred from high lake‐water salinities, and low water levels and an extended duration of nearshore sea‐ice. A second climate optimum occurred between 7400 and 5230 cal. yr BP when stratified, open water conditions during spring and summer characterised the marine coast of Prydz Bay. From 5230 until 2750 cal. yr BP sea‐ice duration in Prydz Bay increased, with conditions similar to the present day. A short return to stratified, open water conditions and a reduction in nearshore winter sea‐ice extent is evident between 2750 and 2200 cal. yr BP. Simultaneously, reconstructions of lake water depth and salinity suggests relatively humid and warm conditions on land between 3000 and 2000 cal. yr BP, which corresponds to a Holocene Hypsithermal reported elsewhere in Antarctica. Finally, dry conditions are recorded around 2000, between 760 and 690, and between 280 and 140 cal. yr BP. These data are consistent with ice‐core records from Antarctica and support the hypothesis that lacustrine and marine sediments on land can be used to evaluate the effect of long‐term climate change on the terrestrial environment. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

11.
A comparison of ore-lead isotope ratios of Pb-Zn deposits hosted in Triassic carbonates of the Eastern and Southern Alps with the isotopic composition of trace leads of their host rocks, of Triassic volcanics, and of the underlying clastic sediments shows that these rocks could have supplied only part of the ore lead. The isotopic signature of feldspar lead from crystalline basement rocks, however, reveals that they must have contributed a significant amount of metal to these deposits. The presence of barite and of thallium is also indicative that feldspars were the main source of lead. Arsenic is one of the few important trace elements in these deposits and is known to occur in some areas of Lower Paleozoic metasediments in unusually high concentrations. Any model explaining the origin of these deposits must consider the extensive leaching of the basement and to some extent of the overlying clastic sediments as well. How the metal-bearing solutions entered the lagoonal back-reef areas is still open to question as feeder channels have not yet been positively identified. The results further demonstrate that the basement also acted as a metal source for galena-bearing deposits hosted in Permian sediments, vein-type deposits in Permian volcanics, and probably the barite-fluorite polymetallic deposits along a Devonian erosional surface in the Carnic Alps as well.  相似文献   

12.
湘江入湖河段沉积物重金属污染及其Pb同位素地球化学示踪   总被引：12，自引：0，他引：12  
湘江是我国重金属污染最严重的河流之一.本次工作利用等离子质谱(ICP-MS)和多接收同位素质谱(MC-ICP-MS)等技术,对湘江入湖河段沉积物进行了系统的重金属微量元素和Pb同位素分析.结果表明,湘江河床沉积物明显富集Bi、Sc、V、Mn、Ni、Cu、Zn、Pb、Cd、Sn、Sb等多种重金属微量元素,而湖盆沉积物重金...  相似文献   

13.
Lake Shala, the deepest lake in the internal Galla lakes basin of the Ethiopian Rift, fills a depression in Pleistocene volcanic rocks. Its sodium-bicarbonate (-chloride) water (salinity 16 g/l) is remarkably low in earth alkalines and sulphate. Stratification is indicated by different ion concentrations in the surface and bottom waters and by a thermocline in a water depth of 50–70 m. Hot soda springs emerging on the shores of Lakes Shala and Langano are believed to be derived from a hot saline underground reservoir recharged by meteoric waters. The ion composition of the hot spring waters is uniform and matches that in the Galla Lakes except for total salinities. Anomalous heavy metal concentrations are lacking in lake and hot spring waters. Sediments of Lake Shala belong to an extremely fine-grained group of deposits. They are poorly sorted and the lateral distribution of the grain sizes does not follow the normal scheme for aquatic depositional environments. A belt, 50–100 m below lake level containing the finest-grained sediments, separates the shallow periphery of the lake bottom from the deep center, both characterized by coarser-grained deposits. The sediments consist of a large portion of glassy components. A poorly cristallized smectite is most abundant in the clay mineral group. The components of the sand fraction are quartz, feldspar, glass particles and occasionally calcite. Nickel, cobalt and lead are depleted in the Lake Shala sediments compared with the averages of shales. Iron, manganese and zinc are relatively high. Silver, cadmium and some of the rare earth elements are enriched by factors of > 5.  相似文献   

14.
Factors controlling the distribution of mining-derived Cu, Pb and Zn in the waters and bottom sediments of a large Andean lake (Lago Junin, Peru) have been assessed based on sample collections in May/June 1997 (dry season) and February/March 1998 (wet season). Relatively low levels of trace metals detected in surface waters of the lake during the dry season contrasted greatly with the high values observed during the wet period. Dry season concentrations of total Zn, Cu and Pb in the central lake basin averaged 41, 4.4 and 0.24 µg/L, respectively. In contrast, the respective wet season concentrations of total Zn, Cu and Pb in areas of the main basin ranged up to 387, 52 and 40 µg/L. The seasonal variability in metal concentrations largely reflects an increase in the concentration of particulate metal phases during the wet season. Such observations can be attributed to changes in sediment loadings associated with mining-derived river inputs and changes in lake circulation resulting from hydroelectric dam operations. Surface sediments are characterized by lake-wide enrichments of Zn, Cu and Pb, with maximum concentrations reaching as high as 5, 0.25 and 0.7 wt%, respectively. Estimated rates of authigenic metal accumulation are not sufficient to account for the elevated metal concentrations in the main basin of the lake, indicating that metal distributions are governed by the accumulation of metal-rich particulates. Variations in the spatial distributions of Zn, Cu and Pb are suggested to be a function of varying host phases and textural sorting.  相似文献   

15.
武汉市墨水湖沉积物重金属污染特征与防治对策   总被引：8，自引：2，他引：8  
苏春利  王焰新 《矿物岩石》2006,26(2):111-116
武汉市墨水湖重金属污染严重,其污染特征在我国城市湖泊中具代表性。在对墨水湖不同湖区沉积物中重金属污染物空间分布特征进行分析的基础上,应用地积累指数法探讨不同重金属元素含量随深度变化的规律和原因,并对墨水湖沉积物中重金属的污染程度进行评价表明:墨水湖沉积物中重金属元素锌和汞污染最为严重,污染程度由高到低依次为:Zn>Hg>Cu>C r>Pb>A s;从整个湖区来看,分布有排污口的周边湖区污染严重,湖心污染程度较低;沉积物中主要重金属元素含量随深度增加而降低,其变化规律主要受污染状况的影响,沉积物颗粒粒径的变化和早期成岩作用的影响不大。为了改善墨水湖水质条件和重金属污染严重的现状,必须在截污、疏浚和引水工程等基本治理措施保护下,重建和恢复沉水植物系统,才能从根本上改善湖泊水质。  相似文献   

16.
The distributions of particulate elements (Al, P, Mn, Fe, Co, Cu, Zn, Cd, and Pb), dissolved trace metals (Mn, Fe, Co, Cu, Zn, and Cd), and dissolved nutrients (nitrate, phosphate, and silicic acid) were investigated in the Gulf of the Farallones, a region of high productivity that is driven by the dynamic mixing of the San Francisco Bay plume, upwelled waters, and California coastal surface waters. Particulate metals were separated into >10 and 0.4-10 μm size-fractions and further fractionated into leachable (operationally defined with a 25% acetic acid leach) and refractory particulate concentrations. Dissolved metals (< 0.4 μm pore-size filtrate) were separated into colloidal (0.03-0.4 μm) and soluble (<0.03 μm) fractions. The percent leachable particulate fractions ranged from 2% to 99% of the total particulate concentration for these metals with Mn and Cd being predominantly leachable and Fe and Al being predominantly refractory. The leachable particulate Pb concentration was associated primarily with suspended sediments from San Francisco Bay and was a tracer of the plume in coastal waters. The particulate trace metal data suggest that the leachable fraction was an available source of trace metal micronutrients to the primary productivity in coastal waters. The dissolved trace metals in the San Francisco Bay plume and freshly upwelled surface waters were similar in concentration, with the exception of Cu and Co, which exhibited relatively high concentrations in plume waters and served as tracers of this water mass. The dissolved data and estimates of the plume dynamics suggest that the impact of anthropogenic inputs of nutrients and trace metals in the San Francisco Bay plume contributes substantially to the concentrations found in the Gulf of the Farallones (10-50% of estimated upwelled flux values), but does not greatly disrupt the natural stoichiometric balance of trace metal and nutrient elements within coastal waters given the similarity in concentrations to sources in upwelled water. In all, the data from this study demonstrate that the flux of dissolved nutrients and bioactive trace metals from the San Francisco Bay plume contribute to the high and relatively constant phytoplankton biomass observed in the Gulf of the Farallones.  相似文献   

17.
The sedimentary basin of Gavkhuni playa lake includes two sedimentary environments of delta and playa lake. These environments consist of mud, sand and salt flats. There are potentials for concentration of heavy metals in the fine-grained sediments (silt and clay) of the playa due to existence of Pb/Zn ore deposits, industrial and agricultural regions in the water catchment of Zayandehrud River terminating to this area. In order to study the concentration of heavy metals and the controlling factors on their distribution in the fine-grained sediments, 13 samples were taken from the muddy facies and concentration of the heavy metals were determined. The results showed that the heavy metal concentrations range in the sediments (in ppm) are Mn (395.5–1,040), Sr (100.4–725.76), Pb (14.66–91.06), Zn (23.59–80.9), Ni (37–73.66), Cu (13.83–29.83), Co (5.73–13.78), Ag (3.03–4.76) and Cd (2.3–5.5) in their order of abundances. The concentration of Ag is noticeable in the sediments relative to the average concentration of this element in mud sediments. The amounts of Pb and Zn are relatively high in all the samples in comparison with the other elements. The concentration of Ni is relatively high in the oxidized samples. The distribution of Pb is directly related to organic matter content of the sediments. The concentrations of Zn, Sr, Cu, Co and Cd in the samples of the playa are lower than those in the delta. The amount of illite is another factor influencing Zn and Pb concentrations. Sr is more concentrated in the sediments with the high content of calcium carbonate. The distribution pattern of Cu, Co, Pb and Mn resembles to that of the clay content of the sediments. The clay content shows positive correlations with Co, Cu and Mn concentrations and negative correlation with Ag. The Sr and Ag concentrations are positively correlated with the amount of CaCO3. The amounts of Co, Cu, Ni and Mn show negative correlations with the calcium carbonate content. Pb and Co are noticeably correlated with Mn.  相似文献   

18.
This study emphasizes to testify the potential of geochemical proxies of lacustrine sediments as indicative of past climatic changes since the last deglaciation over the catchment of a small closed lake in South China. Based on the study on the core K02 from Dahu Swamp, a small lake in the eastern Nanling Mountains, we inferred that chemical features of clastic materials, which were mainly derived from the granite weathering crust and transported by surface runoff into this lake, possibly had played an important role in affecting chemical characteristics of the sediments. Wetter climatic conditions would lead to stronger chemical weathering intensity (CWI), resulting in more soluble and mobile elements being easily leached downward in granite weathering crusts and the insoluble ones being enriched in the top materials of the weathering crusts. In contrast, dry conditions would exert a converse influence. Although this study presents a different climatic implication of geochemistry from lacustrine sediments in South China from that in north-central China, the results demonstrate that chemical elements of sediments in the small lake in South China can be utilized to reflect the CWI, which was closely in association with variations in temperature and precipitation in the lake catchment.  相似文献   

19.
<正>Considerable controversy exists over whether or not extensive glaciation occurred during the global Last Glacial Maximum(LGM) in the Larsemann Hills.In this study we use the in situ produced cosmogenic nuclide ~(10)Be(half life 1.51 Ma) to provide minimum exposure ages for six bedrock samples and one erratic boulder in order to determine the last period of deglaciation in the Larsemann Hills and on the neighboring Bolingen Islands.Three bedrock samples taken from Friendship Mountain(the highest peak on the Mirror Peninsula,Larsemann Hills;～2 km from the ice sheet) have minimum exposure ages ranging from 40.0 to 44.7 ka.The erratic boulder from Peak 106(just at the edge of the ice sheet) has a younger minimum exposure age of only 8.8 ka.The minimum exposure ages for two bedrock samples from Blundell Peak(the highest peak on Stornes Peninsula,Larsemann Hills;～2 km from the ice sheet) are about 17 and 18 ka.On the Bolingen Islands(southwest to the Larsemann Hills;～10 km from the ice sheet),the minimum exposure age for one bedrock sample is similar to that at Friendship Mountain(i.e.,44 ka).Our results indicate that the bedrock exposure in the Larsemann Hills and on the neighboring Bolingen Islands commenced obviously before the global LGM(i.e.,20-22 ka),and the bedrock erosion rates at the Antarctic coast areas may be obviously higher than in the interior land.  相似文献   

20.
Trace metal dynamics in a seasonally anoxic lake   总被引：1，自引：0，他引：1  
Selected results are presented from a detailed 12-month study of trace metals in a seasonally anoxic lake. Dissolved concentrations of Fe, Mn, organic carbon, Cd, Cu, Pb, Zn, and pH were determined in the water column and the interstitial waters on 39 occasions. Trace metal concentrations remained low throughout the year in both water column and pore waters. There was evidence for some remobilization at the sediment-water interface but sediments deeper than 3 cm acted as a sink throughout the year. Variations in the water concentrations were largely associated with increased loading during periods of heavy rainfall. During the summer, concentrations of Cu and Zn in the waters overlying the sediments were enhanced by release from decomposing algal material. Similarly, enhanced concentrations of Cd, Cu, Pb, and Zn were observed during periods of much reduced mixing during ice-cover. Although there were large seasonal variations in the concentrations of dissolved and particulate Fe and Mn, there were no comparable changes in the concentrations of trace metals.  相似文献   

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