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1.
Thirty-three bottom sediments were collected from the Potomac and Anacostia rivers, Tidal Basin, and Washington Ship Channel in June 1991 to define the extent of trace metal contamination and to elucidate source areas of sediment contaminants. In addition, twenty-three sediment samples were collected directly in front of and within major storm and combined sewers that discharge directly to these areas. Trace metals (e.g., Cu, Cr, Cd, Hg, Pb, and Zn) exhibited a wide range in values throughout the study area. Sediment concentrations of Pb ranged from 32.0 μg Pb g?1 to 3,630 μg Pb g?1, Cd from 0.24 μg Cd g?1 to 4.1 μg Cd g?1, and Hg from 0.13 μg Hg g?1 to 9.2 μg Hg g?1, with generally higher concentrations in either outfall or sewer sediments compared to river bottom-sediments. In the Anacostia River, concentration differences among sewer, outfall, and river sediments, along with downriver spatial trends in trace metals suggest that numerous storm and combined swers are major sources of trace metals. Similar results were observed in both the Tidal Basin and Washington Ship Channel. Cadminum and Pb concentrations are higher in specific sewers and outfalls, whereas the distribution of other metals suggests a more diffuse source to the rivers and basins of the area. Cadmium and Pb also exhibited the greatest enrichment throughout the study area, with peak values located in the Anacostia River, near the Washington Navy Yard. Enrichment factors decrease in the order: Cd>Pb>Zn>Hg>Cu>Cr. Between 70% and 96% of sediment-bound Pb and Cd was released from a N2-purged IN HCl leach. On average, ≤40% of total sedimentary Cu was liberated, possibly due to the partial attack of organic components of the sediment. Sediments of the tidal freshwater portion of the Potomac estuary reflect a moderate to highly components area with substantial enrichments of sedimentary Pb, Cd, and Zn. The sediment phase that contains these metals indicates the potential mobility of the sediment-bound metals if they are reworked during either storm events or dredging.  相似文献   

2.
Three cores, one kilometer apart, from each of seven locations along Lake Erie were analyzed for heavy metals and dated by 210Pb techniques. The sedimentary record of anthropogenic inputs of heavy metals parallels the increasing intensity of cultural activity in the lake basin. On the average, pollution sources annually contribute 0.4 μg of Cd, 12 μg of Cu, 12 μg of Pb and 36 μg of Zn deposited per each cm2 of the Eastern Basin sediments: 0.5, 8.8, 11 and 31 μg of Cd, Cu, Pb and Zn, respectively, deposited per cm2 of Western Basin sediments and 0.7, 1.4, 2.0 and 5.6 μg of Cd, Cu, Pb and Zn, respectively, deposited per cm2 of fine-grained sediments in the Central Basin. These anthropogenic flux rates exceed the pre-colonial data by 80–600%. The mean flux rates for 210Pb into the Eastern. Central and Western Basins are 0.45, 0.07 and 0.15dpm cm?2 yr?1. respectively. From an inventory of sources and sinks of the metals, it is shown that about 2500 × 103 kg of Cu. 1900 × 103 kg of Pb and 6750 × 103kg of Zn are delivered annually into the lake. The calculated retention in the lake sediments of 45%, 65% and 35% of the total annual inputs of Cu. Pb and Zn, respectively, agrees closely with the accumulation of data derived from sediment analyses. Sewage discharges, direct and indirect, are shown to be an important source of metal in the lake. The mean residence times in the water column are inferred to be 104 days for Cu. 180 days for Pb and 152 days for Zn.  相似文献   

3.
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   

4.
云蒙湖表层沉积物重金属分布特征及风险评价   总被引：1，自引：0，他引：1  
为了解云蒙湖表层沉积物中重金属的污染状况,选取云蒙湖沉积物中6种重金属(Cu、Zn、Pb、Cr、Cd、As)作为研究对象,测定并分析其在云蒙湖表层沉积物中的分布、来源及生态风险,以期为云蒙湖沉积物中重金属污染治理及饮用水安全保障提供依据。采用富集系数法、相关性分析及聚类分析对重金属来源进行分析,并选用富集系数法、地累积指数法和潜在生态危害指数法对重金属污染程度及潜在生态危害进行了评价。结果表明:云蒙湖表层沉积物中6种重金属Cu、Zn、Pb、Cr、Cd、As平均含量分别为20.9、73.1、23.1、62.0、0.4和4.5 mg/kg;与临沂市土壤背景比较,Cd、Zn和Cr的含量超过临沂市土壤背景值,Cd污染最严重。重金属来源分析结果显示:Cd受人类活动影响较大,可能与区域农业和林业施肥有关;Cu、Zn、Pb、Cr和 As这几种重金属以自然来源为主。综合富集系数法、地累积指数法和潜在生态危害指数法3种评价方法的结果得出,云蒙湖表层沉积物中Cd 为最主要的污染元素,且具有较强的生态危害。  相似文献   

5.
Three sediment cores were collected in the Scheldt, Lys and Spiere canals, which drain a highly populated and industrialized area in Western Europe. The speciation and the distribution of trace metals in pore waters and sediment particles were assessed through a combination of computational and experimental techniques. The concentrations of dissolved major and trace elements (anions, cations, sulfides, dissolved organic C, Cd, Co, Fe, Mn, Ni, Pb and Zn) were used to calculate the thermodynamic equilibrium speciation in pore waters and to evaluate the saturation of minerals (Visual Minteq software). A sequential extraction procedure was applied on anoxic sediment particles in order to assess the main host phases of trace elements. Manganese was the most labile metal in pore waters and was mainly associated with carbonates in particles. In contrast, a weak affinity of Cd, Co, Ni, Pb and Zn with carbonates was established because: (1) a systematic under-saturation was noticed in pore waters and (2) less than 10% of these elements were extracted in the exchangeable and carbonate sedimentary fraction. In the studied anoxic sediments, the mobility and the lability of trace metals, apart from Mn, seemed to be controlled through the competition between sulfidic and organic ligands. In particular, the necessity of taking into account organic matter in the modelling of thermodynamic equilibrium was demonstrated for Cd, Ni, Zn and Pb, the latter element exhibiting the strongest affinity with humic substances. Consequently, dissolved organic matter could favour the stabilization of trace metals in the liquid phase. Conversely, sulfide minerals played a key role in the scavenging of trace metals in sediment particles. Finally, similar trace metal lability rankings were obtained for the liquid and solid phases.  相似文献   

6.
This paper reports a geochemical study of trace metals and Pb isotopes of sediments from the lowermost Xiangjiang River, Hunan province (P. R. China). Trace metals Ba, Bi, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Mo, Cd, Sn, Sb, Pb, Tl, Th, U, Zr, Hf, Nb and Ta were analyzed using ICP-MS, and Pb isotopes of the bulk sediments were measured by MC-ICP-MS. The results show that trace metals Cd, Bi, Sn, Sc, Cr, Mn, Co, Ni, Cu, Zn, Sb, Pb and Tl are enriched in the sediments. Among these metals, Cd, Bi and Sn are extremely highly enriched (EF values >40), metals Zn, Sn, Sb and Pb significantly highly (5 < EF < 20), and metals Sc, Cr, Mn, Co, Ni, Cu and Tl moderately highly (2 < EF < 5) enriched in the river sediments. All these metals, however, are moderately enriched in the lake sediments. Geochemical results of trace metals Th, Sc, Co, Cr, Zr, Hf and La, and Pb isotopes suggest that metals in the river sediments are of multi-sources, including both natural and anthropogenic sources. Metals of the natural sources might be contributed mostly from weathering of the Indosinian granites (GR) and Palaeozoic sandstones (PL), and metals of anthropogenic sources were contributed from Pb–Zn ore deposits distributed in upper river areas. Metals in the lake sediments consist of the anthropogenic proportions, which were contributed from automobile exhausts and coal dusts. Thus, heavy-metal contamination for the river sediments is attributed to the exploitation and utilization (e.g., mining, smelting, and refining) of Pb–Zn ore mineral resources in the upper river areas, and this for the lake sediments was caused by automobile exhausts and coal combustion. Metals Bi, Cd, Pb, Sn and Sb have anthropogenic proportion of higher than 90%, with natural contribution less than 10%. Metals Mn and Zn consist of anthropogenic proportion of 60–85%, with natural proportion higher than 15%. Metals Sc, Cr, Co, Cu, Tl, Th, U and Ta have anthropogenic proportion of 30–70%, with natural contribution higher than 30%. Metals Ba, V and Mo might be contributed mostly from natural process.  相似文献   

7.
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   

8.
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   

9.
《Applied Geochemistry》2000,15(6):807-817
The concentrations of major and trace elements were determined (aqua regia leach and ICP-AES analyses) in stream, lake and dredged sediments downstream of the historical Antskog iron- and copperworks, S.Finland. The levels of Ag, Cd, Cu, Pb and Zn are highly elevated in all studied sediment types: roughly half of the studied lake-sediment samples contain >5 ppm Ag, >15 ppm Cd, >0.1% Cu, >0.1% Pb and >0.3% Zn. In the dredged sediment material located onshore, the concentrations of Ag, Cu and Pb are comparable to those in the polluted lake-sediment samples, while in stream sediments elevated metal concentrations are found especially in samples characterised by high concentrations of organic material. The source of the elevated metal concentrations is the historical metalworks at Antskog, mainly the copperworks of the 19th century. Compared to the limit values for contaminated soils in Finland, the concentrations of Cu, Pb and Zn are on average elevated by factors >10 in the polluted horizons of lake sediments, >5 in the dredged sediment located onshore and >2 at the most heavily contaminated site in the stream. Since the surface waters in the area are used for agricultural purposes and for various leisure activities, it is necessary to make further detailed investigations into the extent of the metal pollution and to determine species, mobility and bioavailability of the metals.  相似文献   

10.
近50年来抚仙湖重金属污染的沉积记录*   总被引：15，自引：8，他引：15  
文章以抚仙湖污染严重的北部和基本未受人类活动影响的中部为研究对象,分别采集了沉积岩芯FB和FZ,通过对岩芯的137 Cs测年和重金属元素(Cu,Ni,Ti,Cr,V,Pb,Cd和Zn)的含量分析,研究了湖泊重金属来源和污染历史,并利用地质累积指数法评价了湖泊重金属污染程度。结果表明:抚仙湖北部的平均沉积速率约为2.0~2.8mm/a;20世纪80年代以前,湖泊北部和中部的重金属元素(Cu,Ni,Ti,V,Pb,Cd,Zn)以自然来源为主;80年代以后,抚仙湖受到人类活动的影响,但湖泊中部Cu,Ni,Ti,V,Pb,Zn以及湖泊北部Cu,Ni,Ti,V仍以自然来源为主;湖泊北部Pb和Zn地质累积指数值小于1,属无污染到中度污染;北部Cd地质累积指数为3~4,达强度污染;中部Cd地质累积指数为2~3,属中强度污染;且Pb,Zn和Cd污染程度有加速增大的趋势。  相似文献   

11.
A total of 29 surface sediments were collected from the Daihai Lake, China. Concentrations of metals (Cu, Pb, Zn, and Cd) were determined using HR-ICP-MS after digestion with the mixture of HNO3–HF–HCl (aqua regia), and chemically fractionated according to the modified the European Community Bureau of Reference sequential extraction procedure. Total organic carbon contents and grain size were also analyzed. Average concentrations (ppm) for Cu (39.4 ± 10.6), Pb (29.9 ± 6.1), Zn (102.6 ± 23.3), and Cd (0.21 ± 0.07) were found in the sediments. The concentrations of metals are relatively higher in the central area of lake, while lower nearby the area with a shallower water depth. Sequential extraction results show that Cu and Zn are mainly distributed in the residual fraction, while Cd is dominantly in the non-residual fraction. Enrichment factor values and geoaccumulation indexes suggest that there are not obvious enrichments of Cu, Pb, and Zn in the sediments, but Cd pollution can be found in most of the area of Daihai Lake. The sources for Cu, Pb, and Zn are attributed to atmospheric deposition, which might be mainly associated with coal combustion. Agricultural runoff in polluted soils and coal combustion might be main sources of the Cd pollution in the lake.  相似文献   

12.
Trace metal profiles in the varved sediment of an Arctic lake   总被引：1，自引：0，他引：1  
Varved (annually-laminated) sediments offer a rare and physically undisturbed archive of past trace metal deposition and limnological conditions. Here, a high-resolution 1,300 year record of metal accumulation is presented from a varved lake sediment on Devon Island in the Canadian High Arctic. Down-core concentration profiles of Cd, Cu and Zn were positively correlated (P < 0.01) with organic C (Cd, Zn) or with leachable Fe (Cu), while distinct sub-surface peaks of these metals coincided with those of Fe, S and other redox-sensitive elements such as Co, Cr and U. The fluxes of these metals since 1854 were correlated with elements such as Ca, Al and La (P < 0.001) which are predominantly of local geological origin. Furthermore, the Cd, Cu and Zn patterns did not match concurrent records in Greenland Summit ice over the last century, nor global industrial emission histories. These facts suggest that inputs from local geological sources, coupled with some degree of post-depositional mobility or association with organic matter inputs, explain the metals’ sedimentary profiles, which were apparently not affected by long-range atmospheric metal pollution. Mercury concentrations were strongly correlated with total diatom abundance over the last 400 yrs, especially during the 20th Century when a two-fold increase in Hg concentrations and a four order-of-magnitude increase in diatoms occurred in tandem. Since 1854, 81% of the variation in Hg flux was associated with diatom and Ca fluxes. A similar correspondence between Hg and diatoms was found in a second lake nearby, confirming that the relationship was not unique to the main study lake. Recent Hg increases in Arctic and sub-Arctic lakes have been attributed to global anthropogenic Hg emissions. We propose an alternative hypothesis for High Arctic lakes: the recent Hg increases may be partly or entirely the product of elevated rates of Hg scavenging from the water column caused by markedly greater algal productivity, which in turn was driven by accelerating climate warming during the 20th Century. Given the important environmental assessment and policy implications if the alternative hypothesis is true, the possible effects of climate warming on sedimentary Hg fluxes in this region deserve further study.  相似文献   

13.
The Dongting Lake, the second biggest freshwater lake in China, consists of three wetlands of national importance, namely the East Dongting Lake, the South Dongting Lake, and the West Dongting Lake. Surface sedi-ments were sampled from 57 locations across the lake. Nutrient concentrations [total organic carbon (TOC), total N (TN) and total P (TP)] and 16 element concentrations (Al, As, B, Ca, Cd, Cr, Cu, K, Fe, Hg, Mn, Ni, Pb, Si, Ti and Zn) in the sediments were measured to investigate the impact of industrialization along the lake's coastline and sev-eral tributaries on the profiles of nutrients and heavy metals in the lake's surface sediments. R-mode cluster analysis (CA) was used to integrate geochemical data. The result showed that euthophication of the Dongting Lake resulted mainly from TN and TOC. The main polluting trace metals are Hg, As, Cd, Zn, Pb and Mn, which are largely ad-sorbed on clay minerals or Fe/Mn oxides, or deposited as carbonates. Principal component analysis (PCA) revealed the source of micropollutants. The worst affected district by heavy metals is the East Dongting Lake, the pollution sources may originate mainly from the Xiangjiang drainage area. The results demonstrated that multivariate methods are the potentially great tools for the interpretation of the environmental data on lake sediments.  相似文献   

14.
The heavy metal contents of Mn, Ni, Cu, Zn, Cr, Co, Pb, Cd, Fe, and V in the surface sediments from five selected sites of El Temsah Lake was determined by graphite furnace atomic absorption spectrophotometer. Geochemical forms of elements were investigated using four-step sequential chemical extraction procedure in order to identify and evaluate the mobility and the availability of trace metals on lake sediments, in comparison with the total element content. The operationally defined host fractions were: (1) exchangeable/bound to carbonate, (2) bound to Fe/Mn oxide, (3) bound to organic matter/sulfides, and (4) acid-soluble residue. The speciation data reveals that metals Zn, Cd, Pb, Ni, Mn, Cu, Cr, Fe, and V are sink primarily in organic and Fe–Mn oxyhydroxides phases. Co is mainly concentrated in the active phase. This is alarming because the element is enriched in Al Sayadin Lagoon which is still the main site of open fishing in Ismailia. Average concentration of the elements is mostly above the geochemical background and pristine values of the present study. There is a difference on the elemental composition of the sediment collected at the western lagoon (Al Sayadin Lagoon), junction, the shoreline shipyard workshops, and eastern beach of the lake. Depending upon the nature of elements and local pollution source, high concentration of Zn, Pb, and Cu are emitted by industrial wastewater flow (shoreline workshops), while sanitary and agricultural wastewater (El Bahtini and El Mahsama Drains) emit Co and Cd in Al Sayadin Lagoon. On the other hand, there is a marked decrease in potentially toxic heavy metal concentrations in the sediments at the most eastern side of the lake, probably due to the successive sediment dredging and improvements in water purification systems for navigation objective. These result show that El Temsah receives concentrations in anthropogenic metals that risk provoking more or less important disruptions, which are harmful and irreversible on the fauna and flora of this lake and on the whole ecobiological equilibrium.  相似文献   

15.
城市内陆型湖泊湿地对城市生态系统具有重要的作用。以武汉市武湖为例,采用数理统计、营养盐指数、地累积指数和潜在生态风险指数等方法,对武湖表层沉积物中的氮、磷、有机质和重金属的平面分布特征、影响因素、富集污染程度、生态风险进行评价。结果表明: 武湖西北部表层沉积物中总氮、总磷和有机质的含量明显高于东南部,武湖周边地表径流和农田是营养元素的主要来源,旱地较水田有利于沉积物中总磷的富集; 武湖沉积物中有机质为内源水生植物和外源陆生植物的混合来源,与总氮具显著正相关关系; 沉积物中重金属含量总体较低,局部呈现高镉,平面上总体北部高于南部; 沉积物中重金属富集程度和潜在风险较低,局部地区镉和铅为轻微富集,镉和汞具中等潜在风险; 沉积物的潜在生态风险为低至中等,潜在生态风险与沉积物中镉的分布高度一致。  相似文献   

16.
太湖沉积物中重金属的地球化学形态及特征分析   总被引：24，自引：2，他引：22  
用连续提取法分析了太湖沉积物5种重金属的地球化学形态,对地球化学形态的组成和地理特征进行了分析研究.重金属地球化学形态配分的共同特点是可交换态最低,残渣态最高.两种形态中Cd的可交换态最高,Cr的残渣态最高,可交换态最低.Cd的碳酸盐态较高,Cr的最低;Pb、Cd的Fe-Mn氧化态较高,Cu的偏低;Cu的有机态最高,Cd的最低;Zn的地球化学形态比例大都处于中间.地域上变化较大的元素是Cd和Cu,变化不明显的元素有Pb和Zn.化学成分中Fe2O3、MnO与重金属地球化学形态的相关性最好,TOC与Cu的形态相关系数最高.综合对比分析表明,太湖沉积物重金属的生物有效性以Cd为最高,其次为Pb.  相似文献   

17.
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   

18.
The lakes of the Himalaya are degrading due to increase in toxic heavy metal loading. This study reports the last 50-year heavy metal pollution loading in the Rewalsar Lake, Himachal Pradesh, India. Sediment cores were recovered to study the pollution loading in the lake sediments. The 137Cs and 210Pb isotope-based sedimentation rate suggest rapid sedimentation in the lake during the last ~50 years. The concentrations of Mn, Cu, Zn, Cd, Pb, Co, Ni, Cr metals in the lake sediments owe its contributions both to the natural and anthropogenic sources. Prior to ca 1990 AD, metal loading was dominated by the lithogenic input, whereas post ca 1990 AD the metal loading was controlled by the anthropogenic factors. The Pb concentration in the lake gradually increased during 1990–2004 and then decreased significantly till present. The higher concentration of Pb seems to be derived from the fossil fuel burning, while the Cr concentration in the lake indicates the use of fertilizer in the catchment area. The lowest concentrations of elements around ca 1990 AD seem to have occurred due to channelization of the lake feeding system.  相似文献   

19.
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   

20.
The Pliocene aquifer receives inflow of Miocene and Pleistocene aquifer waters in Wadi El Natrun depression. The aquifer also receives inflow from the agricultural activity and septic tanks. Nine sediment samples were collected from the Pliocene aquifer in Wadi E1 Natrun. Heavy metal (Cu, Sr, Zn, Mn, Fe, Al, Ba, Cr, Ni, V, Cd, Co, Mo, and Pb) concentrations of Pliocene aquifer sediments were investigated in bulk, sand, and mud fractions. The determination of extractable trace metals (Cu, Zn, Fe, Mn, and Pb) in Pliocene aquifer sediments using sequential extraction procedure (four steps) has been performed in order to study environmental pathways (e.g., mobility of metals, bounding states). These employ a series of successively stronger chemical leaching reagents which nominally target the different compositional fractions. By analyzing the liquid leachates and the residual solid components, it is possible to determine not only the type and concentration of metals retained in each phase but also their potential ecological significance. Cu, Sr, Zn, Mn, Fe, and Al concentrations are higher in finer sediments than in coarser sediments, while Ba, Cr, Ni, V, Cd, Co, Mo, and Pb are enriched in the coarser fraction. The differences in relative concentrations are attributed to intense anthropogenic inputs from different sources. Heavy metal concentrations are higher than global average concentrations in sandstone, USEPA guidelines, and other local and international aquifer sediments. The order of trace elements in the bulk Pliocene aquifer sediments, from high to low concentrations, is Fe?>?Al?>?Mn?>?Cr?>?Zn?>?Cu?>?Ni?>?V?>?Sr?>?Ba?>?Pb?>?Mo?>?Cd?>?Co. The Pliocene aquifer sediments are highly contaminated for most toxic metals, except Pb and Co which have moderate contamination. The active soluble (F0) and exchangeable (F1) phases are represented by high concentrations of Cu, Zn, Fe, and Mn and relatively higher concentrations of Pb and Cd. This may be due to the increase of silt and clay fractions (mud) in sediments, which act as an adsorbent, retaining metals through ion exchange and other processes. The order of mobility of heavy metals in this phase is found to be Pb?>?Cd?>?Zn?>?Cu?>?Fe?>?Mn. The values of the active phase of most heavy metals are relatively high, indicating that Pliocene sediments are potentially a major sink for heavy metals characterized by high mobility and bioavailability. Fe–Mn oxyhydroxide phase is the most important fraction among labile fractions and represents 22% for Cd, 20% for Fe, 11% for Zn, 8% for Cu, 5% for Pb, and 3% for Mn. The organic matter-bound fraction contains 80% of Mn, 72% of Cu, 68% of Zn, 60% of Fe, 35% of Pb, and 30% of Cd (as mean). Summarizing the sequential extraction, a very good immobilization of the heavy metals by the organic matter-bound fraction is followed by the carbonate-exchangeable-bound fraction. The mobility of the Cd metal in the active and Fe–Mn oxyhydroxide phases is the highest, while the Mn metal had the lowest mobility.  相似文献   

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