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1.
《Applied Geochemistry》1998,13(1):59-75
Sediment cores were collected from depositional basins in lakes Michigan, Ontario and Superior to assess spatial and temporal variations in Cu accumulation rates and inventories. Sediment chronologies were determined via 210Pb dating, and 210Pb inventories were used to correct for the effects of sediment focusing. Among the lakes studied, Cu loading histories generally decrease to the present, signifying a regional reduction in the anthropogenic release of Cu to the environment. Focusing-corrected Cu accumulation rates in surficial sediments vary significantly within lakes Michigan and Ontario, suggesting that recent inputs of Cu to these 2 lakes may have been dominated by localized sources. Variations in Cu accumulation rates within Lake Superior are interpreted to be insignificant, suggesting either that Lake Superior is well-mixed with respect to copper inputs or that the lake is dominated by a single source for Cu. Recent measurements of atmospheric fluxes of Cu within the Great Lakes region generally indicate that the atmosphere accounts for less than 50% of the Cu accumulating in surficial sediments. Historical Cu accumulation rates from Lake Superior are poorly correlated with Cu production associated with local smelters, but favorably agree with national production rates. Trends in historical Cu accumulation rates within all 3 lakes may indicate that recent declines in Cu loading can be attributed to the enactment of stricter environmental regulations as well as changes in the use of Cu. Focusing-corrected Cu inventories in lakes Michigan, Ontario, and Superior are generally invariant within a given lake, indicating that, historically, these lakes have been dominated either by a single source or were well-mixed with respect to Cu inputs. The disparity between the results from recent accumulation rates and historical inventories may reflect differences in how the Great Lakes respond to contaminant loading on short (e.g. years) versus long (e.g. decades) timescales.  相似文献   

2.
《Applied Geochemistry》2002,17(4):475-492
Trace metal concentrations in soils and in stream and estuarine sediments from a subtropical urban watershed in Hawaii are presented. The results are placed in the context of historical studies of environmental quality (water, soils, and sediment) in Hawaii to elucidate sources of trace elements and the processes responsible for their distribution. This work builds on earlier studies on sediments of Ala Wai Canal of urban Honolulu by examining spatial and temporal variations in the trace elements throughout the watershed. Natural processes and anthropogenic activity in urban Honolulu contribute to spatial and temporal variations of trace element concentrations throughout the watershed. Enrichment of trace elements in watershed soils result, in some cases, from contributions attributed to the weathering of volcanic rocks, as well as to a more variable anthropogenic input that reflects changes in land use in Honolulu. Varying concentrations of As, Cd, Cu, Pb and Zn in sediments reflect about 60 a of anthropogenic activity in Honolulu. Land use has a strong impact on the spatial distribution and abundance of selected trace elements in soils and stream sediments. As noted in continental US settings, the phasing out of Pb-alkyl fuel additives has decreased Pb inputs to recently deposited estuarine sediments. Yet, a substantial historical anthropogenic Pb inventory remains in soils of the watershed and erosion of surface soils continues to contribute to its enrichment in estuarine sediments. Concentrations of other elements (e.g., Cu, Zn, Cd), however, have not decreased with time, suggesting continued active inputs. Concentrations of Ba, Co, Cr, Ni, V and U, although elevated in some cases, typically reflect greater proportions attributed to natural sources rather than anthropogenic input.  相似文献   

3.
《Applied Geochemistry》2004,19(5):769-786
Heavy metal (Zn, Cd, Cu and Pb) mass balances in the Lot-Garonne fluvial system have been established for 1999 and 2000. The mean annual discharges of these years are close to the mean discharge of the previous decade. The estimated annual dissolved and particulate fluxes in this model watershed integrate daily input from diffuse and point sources, diffusive fluxes at the water/sediment interface, changes in the dissolved-particulate partition and changes in sediment stock. Cadmium, Zn, Cu and Pb entering the Gironde estuary via the Garonne River (11–14 t a−1 of Cd; 1330–1450 t a−1 of Zn; 126–214 t a−1 of Cu and 127–155 t a−1 of Pb) are mainly transported in the particulate phase and the major part (i.e. ∼74 to 96% for Cd, ∼60% for Zn, ∼50 to 60% for Cu and ∼80% for Pb) is transported by the Lot River. The main anthropogenic heavy metal point source is located in a small upstream watershed (Riou-Mort River) accounting for at least 47% (Cd), ∼20% (Zn), ∼4% (Cu) and ∼7 to 9% (Pb) of the total heavy metal inputs into the Garonne River, although it contributes only 1% of the discharge. Mass balances for 1999 suggest that under mean annual hydrologic conditions on the basin scale, the heavy metal budget of the Lot-Garonne fluvial system is balanced and that the stocks of Cd [200 t; Environ. Tech. 16 (1995) 1145] and Zn in the Lot River sediment are constant under mean discharge conditions. Heavy metal input by molecular diffusion at the sediment surface represents an important component of dissolved metal inputs into the system (e.g. 30% for Cu). Except for Cu, these dissolved inputs are totally removed from solution by SPM. Based on the generally constant Zn/Cd (∼50) concentration ratio in sediment cores from the polluted Lot River reaches and the sediment stock of Cd [200 t; Environ. Tech. 16 (1995) 1145], the present day Zn stock in the Lot River sediments has been estimated at about 10,000 t. In addition to the mobilization of river-bed sediment and associated heavy metals by intense floods, local human activities, including river-bed dredging, may strongly modify the heavy metal budget of the river system. In 2000, the dredging-related remobilization of polluted Lot River sediment released 2–6 t Cd. This additional Cd point source was estimated to account for 15–43% of the gross inputs into the Gironde Estuary.  相似文献   

4.
A high-resolution record of Pb deposition in Rhode Island over the past 250 yr was constructed using a sediment core from the anoxic Pettaquamscutt River basin. The sedimentary Pb concentration record shows the well-described maximum associated with leaded gasoline usage in the United States. Diminished Pb variability during recorded periods of local industrial activity (1735 to 1847) supports the greater importance of regional atmospheric lead transport vs. local inputs. The Pb isotopic composition at this site shows a clear maximum in anthropogenic 206Pb/207Pb in the mid-1800s. Similar peaks have also been observed in sediments from Chesapeake Bay and the Great Lakes, suggesting a common source. Possible causes for this event include mining and smelting of Pb ores in the Upper Mississippi Valley district, which accounted for almost all Pb production in the United States in that period. The timing of this event can provide an important stratigraphic marker for sediments deposited in the past 200 yr in the Northeastern United States. The downcore profile of anthropogenic 206Pb/207Pb provides a classic example of how changes in the mixture of ores for production of tetraethyl lead caused a regional-scale shift in the sedimentary record, and suggests that coal could have played a secondary role in Pb emissions after 1920.  相似文献   

5.
《Applied Geochemistry》2000,15(9):1291-1305
Lead concentrations and isotopic compositions were determined on both bulk sediments deposited in the Thau lake in southern France during the last 200 years, and leachates derived from a series of sequential leachings of the sediments, making it possible to identify the sources, natural (i.e. indigenous lithologic) or anthropogenic, and to quantify the different inputs of Pb.Two distinct inputs of Pb could be distinguished. One of these corresponds to the terrigenous material entering the basin, representative of the local natural Pb ‘background’. Its supply remained steady most of the time with 206Pb/207Pb ratios of 1.200±0.003, except at the time of heavy storms producing voluminous and sudden depositions, such as that of September 1875. This Pb supply is mainly hosted by the detrital silicate fraction of the sediments. The second Pb input is a direct consequence of anthropogenic activities of various industrial and domestic emissions in the region, particularly due to the city of Sète and, to a lesser extent, to the villages in the watershed. The 206Pb/207Pb ratios of this input are of 1.142–1.162. The Pb added to gasoline could also be identified in the uppermost sediments, because of its specific 206Pb/207Pb ratios of 1.069–1.094. The leaching experiments also showed that the anthropogenic Pb is mainly hosted by the oxi-hydroxides of the sediments and to a lesser extent by the carbonates. It may also be adsorbed on particle surfaces, while only limited amounts are bound to organic matter.  相似文献   

6.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been used to assess the impact of metal pollution on Porites skeletons taken from the Gulf of Thailand since the 1980s. The collection period coincided with a series of laws enacted by the Thai government to curb environmental pollution. The extent of metal pollution by riverine input, including aerosol deposits, was assessed by comparing the metal/Ca (Me/Ca) ratios in the Thai corals to the ratios of another colony of corals sampled from Rukan-sho, a relatively unpolluted coral reef located in Okinawa, Japan. In this comparison, high riverine inputs of Ba, V, Cd and Pb were observed in the Thai coral samples. Higher V/Ca ratios found in the Thai corals compared to the Rukan-sho coral suggest anthropogenic V inputs due to fuel oil pollution in the Gulf since the late 1990s. The levels of Cd in the coral suggest a gradual decrease in the Gulf in the late 1990s, with a drastic drop in concentration from the 1980s. The historical variation in Pb/Ca ratios recorded in the coral skeletons suggests that exposure to anthropogenic Pb was a result of discharge from urbanized areas from 1984 to 1998, which has been gradually reduced since Thailand prohibited the use of leaded gasoline in the late 1990s.  相似文献   

7.
To investigate the sources and toxicity of metals in Bohai Sea sediments, concentration and geochemical speciation of metals of surface sediments were measured. Metal distributions and principal component analysis suggested that Zn, Pb, Cd, and Ag were largely derived from anthropogenic sources, whereas the majority of the other metals studied here were found to have been derived from natural rock weathering and calcareous marine biota. The major sources of anthropogenic metal inputs to the study region are from the mining industry, port transport services, vehicle exhausts, and agricultural runoff. Empirical sediment quality guidelines and the risk assessment code were used to evaluate the metal toxicities in this area. Our results show that Cd presents a high risk to the ecological system because it was found in the non-residual phase, which tends to be weakly bound and highly bioavailable; Cu, Pb, Ni, and Co pose a low risk; Zn and Cr present no risk. The use of the threshold effects level and effects range-low values of Cd and Cr as guidelines for the Bohai Sea are of limited use as they do not account for the bioavailability and toxicity of the elements in marine environments. Assessment of the annual metal fluxes from riverine and atmospheric sources indicates that the largest contributions of metals to the Bohai Sea were derived from the suspended particulate load of rivers. Furthermore, it was found that the main depositional zones for metals in the Bohai Sea were in estuaries and the center mud zones.  相似文献   

8.
大庆市大气干湿沉降重金属元素通量及来源   总被引：9，自引：0，他引：9  
大庆市是我国最大的陆上油田和重要的石油化工基地,开展重金属沉降通量及来源研究对于评估土壤重金属的来源及人类活动对土壤环境的影响具有重要意义。于2008年4月至次年4月采用被动采样技术共收集大气干湿沉降样品17份,配套土壤17份。通过AFS-230E原子荧光光度计法和ICP-AES全谱直读电感耦合等离子发射光谱法测试与分析了样品中的重金属含量,计算了沉降通量和富集因子。元素沉降通量与配套土壤的相关分析结果表明:Hg、Cd、As、Cr、Ni、Pb的沉降通量较低,而主要来源于人为污染源的Zn、Pb、As、Cd表现出较强或极强度的富集;土壤Zn、Cd的积累与大气沉降之间具有显著的相关关系。其他元素来源较为复杂,不同地区元素沉降通量之间差异显著。沉降量主要与城市地理位置、气候条件、人口数、工业结构、城市化水平等因素有关。  相似文献   

9.
Mineral soil horizons (Ae, Bhf1, Bhf2, Bf, BC and C) were carefully collected from two podzolic soil profiles in the Lake Clair watershed (Québec) in order to assess anthropogenic trace metal accumulation. Petrographic and selective analyses were performed to establish the soil mineralogy and properties. Furthermore, a complete sequential extraction procedure has been applied to help understanding the complex chemical speciation of Pb in forest soils. Chemical speciation of Pb showed a strong vertical gradient: 85% of this metal is mainly partitioned in refractory minerals in the C-horizon whereas in the upper Bhf1 and Ae-horizons, less than 50% of Pb is associated with this fraction. In the Ae-horizon, for example, 35%, 30% and 12% of total Pb, respectively, is associated with the exchangeable, labile organic matter and amorphous Fe-Mn oxides fractions. The distribution of Pb and Cr in the studied forest soils mainly reflects progressive contamination of the watershed by anthropogenic atmospheric sources. The anthropogenic source is indicated by elevated Cr and Pb concentrations in the topsoil (Bhf and Ae) horizons and by strong negative correlation between 206Pb/207Pb ratios and total Pb concentrations. According to these isotopic values, penetration of anthropogenic Pb does not exceed 10 cm in both soil profiles. Below this depth, both Pb concentrations and isotopic ratios remain nearly constant and similar to values observed in pre-anthropogenic sediments from Lake Clair. These values are interpreted as the natural geochemical backgrounds of the watershed. Based on that behaviour, calculated anthropogenic Pb net inputs amounted to between 1.24 and 1.8 g/m2.  相似文献   

10.
Trace element distributions, partitioning, and speciation were examined at 15 sites in the Patuxent River watershed from May 1995 through October 1997 to determine possible sources of trace elements to the river and estuary, to examine the relationship of the trace element discharges to freshwater discharges as well as to land use and geographic region, to validate previous estimates of loadings to the river, and to provide baseline data for trace elements in the Patuxent River watershed and estuary. Six freshwater sites were examined, representing different basins and geographic provinces, and nine sites along the estuarine salinity gradient. Subregions within the watershed varied considerably in concentrations and areal yields for some elements. Concentrations of As, Cd, Ni, Pb, and Zn were elevated in the Coastal Plain sites compared to the Piedmont sites, while Cu and Hg were more evenly distributed. Cadmium, Cu, Hg, Ni, Pb, and Zn showed overall positive correlations with river flow while As and methylHg (meHg) showed negative correlations with river flow. Concentrations of trace elements in the estuarine portion of the river were generally low, and consistent with mixing between Patuxent River water with elevated concentrations and the lower concentrations of the Chesapeake Bay. Interesting features included a local Cd maximum in the low salinity region of the estuary, probably caused by desorption from suspended sediments, and a significant input of water containing high As concentrations from the Chesapeake Bay and from As being released from bottom sediments in summer. Comparisons between the estimated annual flux of trace elements and the estimates of suspected source terms (atmospheric deposition, urban runoff, and known point sources) suggest that, except for Hg, direct atmospheric deposition is small compared to fluvial loads. Current estimates of trace element inputs from point sources or from urban runoff are inadequate for comparison with other sources, because of inappropriate techniques and/or unacceptably high detection limits. A complete examination of trace element dynamics in the Patuxent River (and in other coastal systems) will require better data for these potential sources.  相似文献   

11.
Multivariate statistical approach is used to identify the sources of heavy metals (Bi, Cd, Co, Cr, Mn, Pb, U, V, and Zn) in surface water and freshly deposited riverine sediment samples in Yangzhong city, China. The metal concentration data for the water and sediment samples are reported in terms of basic statistical parameters and metal-to-metal correlations. In both surface water and sediment samples, significant correlations are observed between some metals. Principal component analysis and cluster analysis distinguishes factors of lithogenic and anthropogenic origin. Bismuth, Cd, Co, and Pb (Co only for water samples) contents are controlled by the regional lithogenic high background factor; Co, Mn, U, and V (Co only for sediment samples) are interpreted to be mainly inherited from soil parent materials, while Cr, Zn, and Mn in the two kinds of samples are recognized as the tracer of industrial pollution. Obvious similarity between factor loadings of the two kinds of samples is observed, evidencing that metal variability in the two kinds of samples is controlled by the same sources. Statistical analysis agrees with discussion based on background value and field survey of point-source pollutant affected sediment, making this statistical discussion more convincing.  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.
A dynamic scheme for water movements over a flood in a small watershed was proposed in a previous paper [Ben Othman, D., Luck, J.M., Tournoud, M.G., 1997. Geochemistry and water dynamics: application to short-time scale flood phenomena in a small Mediterranean catchment: I. Alkalis, alkali-earths and Sr isotopes. Chem. Geol. [140] 9–28] based on major, alkali–alkali earth trace elements and Sr isotopes. In the present paper, metal contents and Pb isotope data are reported for the same samples, and compared to natural and anthropogenic local sources analysed for this purpose. Water treatment plants have stable but show relatively large variations, presumably related to yet unidentified (industrial?) Pb sources. Some Cu–Zn-rich chemicals used extensively on vineyards have unradiogenic around 17.7. Local rains sampled over two years show roughly similar low values. Pb from rocks is variable and more radiogenic ( ≈18.8–22.8). Except for the first hours, trace element concentrations in the dissolved load are similar to or slightly higher than those observed over the year, and similar to other moderately anthropogenic areas [Shiller, A.M., Boyle, E.A., 1987. Variability of dissolved trace metals in the Mississippi river. Geochim. Cosmochim. Acta [51] 3273–3277] for [Pb] (0.05–0.45 nM), [Zn] (10–75 nM) and [Cd] (0.03–0.18 nM). Dissolved [U] and [Co] show simple variations correlated to carbonate, related to local natural sources. Most trace elements in the particulate load are strongly correlated. Lead isotopes in the dissolved and particulate loads show ranges over the flood, again similar to those observed over the year ( ≈17.9–18.3), implying the same sources. The very good alignments observed in and vs. diagrams, especially for the particulate, are interpreted as mixing phenomena. Generally Pb isotopic signature of the dissolved load is less radiogenic than the particulate, indicating differences in sources or proportions and absence of isotopic equilibration with respect to the time of transfer. Pb isotopes shift regularly with time away from the road runoff endmember towards more radiogenic values. The strong negative correlation between Pb isotopes in the particulate load and Sr isotopes in the dissolved load, observed for the first time in a small watershed, probably reflects the local coupling between mechanical and chemical erosion, respectively.  相似文献   

14.
Associations between macrobenthic communities, measures of water column and sediment exposure, and measures of anthropogenic activities throughout the watershed were examined for the Chesapeake Bay, U.S. The condition of the macrobenthic communities was indicated by a multimetric benthic index of biotic integrity (B-IBI) that compares deviation of community metrics from values at reference sites assumed to be minimally altered by anthropogenic sources of stress. Correlation analysis was used to examine associations between sites with poor benthic condition and measures of pollution exposure in the water column and sediment. Low dissolved oxygen events were spatially extensive and strongly correlated with benthic community condition, explaining 42% of the variation in the B-IBI. Sediment contamination was spatially limited to a few specific locations including Baltimore Harbor and the Southern Branch of the Elizabeth River and explained about 10% of the variation in the B-IBI. After removing the effects of low dissolved oxygen events, the residual variation in benthic community condition was weakly correlated with surrogates for eutrophication—water column concentrations of total nitrogen, total phosphorus, and chlorophylla. Associations between benthic conditions and anthropogenic inputs and activities in the watershed were also studied by correlation analysis. Benthic condition was negatively correlated with measures of urbanization (i.e., population density, point source loadings, and total nitrogen loadings) and positively correlated with watershed forestation. Significant correlations were observed with population density and nitrogen loading below the fall line, but not above it, suggesting that near-field activities have a greater effect on benthic condition than activities in the upper watershed. At the tributary level, the frequency of low dissolved oxygen events and levels of sediment contaminants were positively correlated with population density and percent of urban land use. Sediment contaminants were also positively correlated with point source nutrient loadings. Water column total nitrogen concentrations were positively correlated with nonpoint nutrient loadings and agricultural land use while total phosphorus concentrations were not correlated with land use or nutrient loadings. Chlorophylla concentrations were positively correlated with nitrogen and phosphorus concentrations in the water column and with agricultural land use but were not correlated with nutrient loads.  相似文献   

15.
The distribution, accumulation, and ecological risk of heavy metals (Cu, Cd, Pb, Zn, Ni, Cr, and As) in the surface sediment were investigated in the upper reaches of Hunhe River, Northeast China. Sediment samples from 51 points throughout the upper reaches of Hunhe River were collected and measured for heavy metal concentrations, TN content, and TP content. Results showed that heavy metal concentrations at the vicinity of mines and towns were higher than those at other locations. According to sediment quality guidelines (SQGs), Cd and Zn were enriched in the sediments. The correlation analysis and principal component analysis (PCA) were conducted to assess the heavy metal sources. Close correlations between metal distribution and TP indicated that the sediments may be affected by application of phosphate fertilizer. Elements, Cu, Cd, Pb, Zn, and As, were grouped together, reflecting they were released from the same sources. PCA suggested that their primary sources were anthropogenic, namely mining and extensive use of fertilizers. Therefore, heavy metal pollution due to mining and agricultural intensification in the upper Hunhe River basin should be taken into account during the formation of regional management strategies for the water environment.  相似文献   

16.
Upcoming International Events   总被引：3，自引：0，他引：3  
Metals in lacustrine sediment have both anthropogenic and natural sources. Because of intensified human activities, the anthropogenic input of metal elements has exceeded the natural variability. How to distinguish the anthropogenic sources in lake sediments is one of the tasks in environmental management. The authors present a case study, which combined the geochemical and statistical methods to distinguish the anthropogenic sources from the natural background. A 56 cm core (core DJ-5) was collected from Dongjiu Lake, Taihu Lake catchment, China. The concentration distributions of Al, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, Pb, Sr, Ti, V and Zn in core DJ-5 indicated that Dongjiu Lake had serious Cd pollution, and the concentrations of Cr, Cu, Pb, Mn and Zn had also exceeded the Chinese State Standards of Soil Environmental Quality in the upper layer of the core. Using Al as a reference element, the other metals were normalized and compared with their baselines to calculate the enrichment factors (EFs). The principal component analysis (PCA) of metal concentrations was performed using ViSta6.4. The results of EFs and PCA indicated that the concentration variations of Cd, Cu, Pb, Mn and Zn were mainly caused by the anthropogenic sources, and the concentration variations of Cr and Ni were influenced by both the anthropogenic and natural factors, while the other metals were mainly derived from the natural sources. Intensified human activities within the lake catchment area resulted in the increase of heavy metal inputs directly and the acceleration of erosion which caused other metal elements to deposit in the aquatic environment. The results of this work will be useful in probing changes forced by humans in the lake environment and in adjusting human activity in restoring the lake environment.
Yanhong WuEmail:
  相似文献   

17.
Sedimentation rates were determined by210Pb in three sediment cores from the main basin of Lake Constance. Rates vary from 0.094 to 0.133 g cm?2y?1, in agreement with previous determinations. A constant radionuclide flux (CR) model reveals long-term, quasi-synchronous fluctuations of sedimentation rate on the basin-wide scale. On average, the rate of sedimentation remains much the same from the beginning of this century indicating little effect of human activity in the watershed on fine-silt sediment supply. The anthropogenic fluxes of Zn, Pb, and Cd in the three cores are compared and the application of210Pb as a heavy metal tracer in Lake Constance is examined. It seems to be a very good tracer for Pb, moderately good for Zn and Cu, and not useful for Cd.  相似文献   

18.
Stable Pb isotope profiles in dated lake sediment cores were used to gauge the relative amounts and possible sources of anthropogenic Pb deposited from the atmosphere in different regions of the Canadian Arctic. A distinct north-south difference was found. In four High Arctic lakes (i.e., north of 66°N) in this study, recent Pb isotopic shifts or concentration increases attributable to anthropogenic Pb were negligible. The maximum possible contribution from anthropogenic Pb was 0 to 19% of acid-leachable Pb in the 1980s or 1990s. In contrast, two lakes in the Hudson Bay region displayed significantly lower Pb isotope ratios and threefold to fivefold increases of Pb concentrations in modern sediments, corresponding to anthropogenic Pb inputs of at least 72 to 91% of leachable Pb. Eurasian urban and industrial Pb is known to dominate the High Arctic atmosphere. A possible explanation for its negligible influence on northern lake sediments is that atmospheric Pb deposition at northern latitudes is reduced compared with southern regions and is small compared to local geological inputs. 210Pb deposition declines with increasing latitude, apparently because of declining precipitation rates; stable Pb deposition may be similarly affected. Meteorological considerations and variations in the post-1900 Pb isotopic trajectories indicated that the predominant anthropogenic Pb source region in NW Hudson Bay was Eurasia, while in SE Hudson Bay, it was Canada and the United States, with a minor Eurasian component.  相似文献   

19.
笔者应用因子克里格分析方法,研究了珠江口西部海域388个表层沉积物中7种重金属元素Cd, Ni,Cu,Zn,Pb,Cr和As的空间结构特征,识别并分离了重金属元素不同尺度的空间主成分及其分布特征,探讨了不同空间尺度重金属的物源及控制因素。结果显示,研究区7种重金属元素在空间上存在块金尺度、局部尺度(变程为60 km的球状结构)和区域尺度(变程为160 km的球状结构)3种尺度的空间变化。以迭代算法模拟了研究区重金属元素线性协同区域化模型。根据不同尺度上区域化因子的主成分得分分布特征可知:局部尺度上,F1因子(Zn,Cr,Ni,Cu)和F2因子(As)的高值区表现为"牛眼"状局部特征,并分布在陆地沿海的河口或者港湾区,指示了可能受人为污染成分影响的重金属区域。其中,雷州半岛东部沿海是最可能的重金属污染区,其空间分布主要受控于局部的地形、海流等因素。F2因子不同于F1的空间分布,主要在于As不同于Zn,Cr,Ni,Cu等的地球化学行为。区域尺度上,F1(Zn,Cr,Ni)和F2(As)因子主要反映了不同陆源母岩物质的影响。Zn,Cr,Ni等主要源于华南大陆陆源母岩物质,而As主要受到海南岛陆源母岩物质的控制。F1和F2因子得分高值区整体上表现为NNE向自陆地向较深海域延伸的"片状"分布特征,推测其主要受到海平面变化及NNE向区域性海洋环流的控制。  相似文献   

20.
Improving the geochemical database available for characterising potential natural and anthropogenic aerosol sources from South America and Southern Africa is a critical precondition for studies aimed at understanding trace metal controls on the marine biogeochemical cycles of the South Atlantic Ocean. We here present new elemental and isotopic data for a wide range of sample types from South America and Southern Africa that are potentially important aerosol sources. This includes road dust from Buenos Aires and lichen samples from Johannesburg, soil dust from Patagonia, volcanic ash from the Andean volcanic belt, and aerosol samples from São Paulo. All samples were investigated for major (Al, Ca, Fe, Mg, Na, K, Mn) and trace element (Cd, Co, Cr, Cu, Ni, Pb, REE, Sc, Th, Y, V, Zn) concentrations and Nd and Pb isotopic compositions. We show that diagrams of 208Pb/207Pb vs. εNd, 208Pb/207Pb vs. Pb/Al, 1/[Pb], Zn/Al, Cd/Al, Cu/Al, and εNd vs. Pb/Al, and 1/[Nd] are best suited to separate South American and South African source regions as well as natural and anthropogenic sources. A subset of samples from Patagonia and the Andes was additionally subjected to separation of a fine (<5?μm) fraction and compared to the composition of the bulk sample. We show that differences in the geochemical signature of bulk samples between individual regions and source types are significantly larger than between grain sizes. Jointly, these findings present an important step forward towards a quantitative assessment of aeolian trace metal inputs to the South Atlantic Ocean.  相似文献   

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