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1.
Sequential core sediments from northwestern Taihu Lake in China were analyzed for grain size, organic carbon and heavy metal content. The sediments are composed of organic-poor clayey-fine silts. The chemical speciations of Cu, Fe, Mn, Ni, Pb, and Zn were also analyzed using the BCR sequential extraction procedure. Cu, Fe, Ni, and Zn are mainly associated with the residue fraction; Mn is concentrated mainly in exchangeable/carbonate fraction and residue fraction; and Pb mainly in Fe/Mn oxide fraction and organic/sulfide fraction. The exchangeable/carbonate fractions of Cu, Fe, Ni, Zn and Pb are lower. The fractions of Ni, Pb and Zn bound to the Fe/Mn oxide have significant correlations with reducible Mn; the organic/sulfide fractions of Cu, Mn, Ni, Pb, and Zn have significant correlations with TOC. The extractable fractions of Cu, Mn, Ni, Pb, and Zn are high at the top 4 cm of the core sediments as compared to those in the deeper layers, showing the anthropogenic input of heavy metals is due to rapid industrial development. The heavy metal pollution history of the sediments has been recorded since the late 1970s, determined by the result of ^137Cs dating. 相似文献
2.
Distribution and enrichment of heavy metals in a sediment core from the Pearl River Estuary 总被引：5，自引：1，他引：4
Baolin Liu Ke Hu Zhenglong Jiang Juan Yang Ximing Luo Aihua Liu 《Environmental Earth Sciences》2011,62(2):265-275
A sediment core collected from coastal zone near the Qiao Island in the Pearl River Estuary was analyzed for total metal concentrations,
chemical partitioning, and physico-chemical properties. Three vertical distribution patterns of the heavy metals in the sediment
core were identified, respectively. The dominant binding phases for Cu, Pb, Cr, and Zn were the residual and Fe/Mn oxides
fractions. Cd in all sediments was mainly associated with exchangeable fraction. Influences of total organic carbon content
and cation exchange capacity on the total concentrations and fractions of almost all the metals were not evident, whereas
sand content might play an important role in the distributions of residual phases of Cr, Cu, Pb, and Zn. In addition, sediment
pH had also an important influence on the Fe/Mn oxides, organic/sulfide and residual fractions of Cr, Cu, and Zn. Contamination
assessment on the heavy metals in the sediment core adopting Index of Geoaccumulation showed that Cr, V, Be, Se, Sn, and Tl
were unpolluted, while Cu, Ni, Pb, Zn, Cd, and Co were polluted in different degrees throughout the core. It was remarkable
that the various pollution levels of the metals from moderate (for Cu, Pb, and Zn) to strong (for Cd) were observed in the
top 45 cm of the profiles. The relative decrease of the residual fraction in the upper 45 cm of the core is striking, especially
for Zn and Cu, and, also for Pb, and Cr. The change in fraction distribution in the upper 45 cm, which is very much contrasting
to the one at larger depths, confirms that the residual fraction is related to the natural origin of these metals, whereas
in the upper part, the non-residual fractions (mainly the Fe/Mn oxides fraction) are increased due to pollution in the last
decade. The possible sources for Cu, Pb, Zn, and Cd contaminations were attributed to the increasing municipal and industrial
wastewater discharges, agricultural runoff, atmospheric inputs, and runoff from upstream mining or smelting activities, which
may be associated with an accelerating growth of economy in the Pearl River Delta region in the past decade. 相似文献
3.
恬矿库周围土壤中重金属存在形态特征研究 总被引：48，自引：4，他引：44
通过对大冶铜绿山铜铁矿尾矿库周围土壤中重金属形态分析实验,研究了重金属各种形态在土壤中的分布特征。由对比实验可知,尾矿库周围土壤中Ｃｕ、Ｐｂ、Ｚｎ、Ｃｄ等重金属含量都显著地高于对照样品,书经受到重金属的严重污染。土壤中重金属形态分布征为：ｗ（Ｃｒ、Ｚｎ、Ｆｅ）;可变换态〈碳酸盐态〈有机态〈铁锰氧化态〈残渣态;ｗ（Ｃｕ、Ｐｂ）：可变换态〈碳酸盐态〈有机态〈残渣态〈铁锰氧化态;ｗ（Ｃｄ）：残渣态,有机 相似文献
4.
Acidic ion-exchanger was applied to the selective extraction of heavy metals in carbonate phases of recent lake sediments. Cr was not detected and Fe and Cu contents were reduced by factors of three to ten, relative to non-carbonate fractions of the sediment samples. Values obtained for Mn and Zn exemplify the effects of dilution was well as enrichment, both originating from increased carbonate percentages. Determinations on grain-sized fractions from Bodensee samples suggest that elevated inputs of dissolved Zn, which partly originate from human activities, may be immobilized by authigenic carbonate precipitation. 相似文献
5.
Study on effective species of heavy metals in lacustrine sediment core from Xijiu Lake,Taihu Lake catchment,China 总被引：2，自引：1，他引：1
Zhaobin Sun Yanhong Wu Shuchun Yao Enfeng Liu Fuchun Li 《Environmental Earth Sciences》2009,59(2):371-377
The BCR sequential extraction procedure is applied to probe into the speciation distribution of heavy metals (Cd, Cr, Zn,
Cu and Pb) in lake sediments of Core XJ2 in Xijiu Lake, Taihu Lake catchment, China. The results showed that the effective
species concentration of this five heavy metal elements increased obviously during the past century, the proportions of organic/sulphide
fractions of Zn, Cu and Pb decreased while the Fe–Mn oxide fractions increased, and the proportion of Fe–Mn oxide fractions
of Cd decreased while the exchangeable and carbonate fractions increased. The concentrations of exchangeable and carbonate
fractions of these five elements were increased in the past century, especially the proportions of these fractions of Cd,
Zn, Cu and Pb increased prominently. These changes could be attributed to the anthropogenic pollution. Since the changes of
the heavy metal concentrations were corresponding to the history of human activities, especially the industry development,
within the catchment. 相似文献
6.
在放射性核素137Cs和210Pb精确计年的基础上,建立了长江中游网湖近代沉积物年代序列。通过对沉积物中金属元素含量和粒度的测定,结合相关的文献资料,分析了100多年来网湖沉积物中重金属元素的垂直分布特征、物源变化,以及自然因素和人类活动对其的影响,最后采用地累积指数法和潜在生态危害指数法进行了重金属污染评价。研究结果表明： 20世纪50年代以前,人类活动对重金属元素沉积影响不大,重金属元素含量低于或接近参考的背景值,主要表现为自然沉积。其中1920～1950年间,流域高频率的洪灾使网湖沉积物中粘土物质减少,战乱和血吸虫病造成阳新县工农业生产衰退,人口急剧下降,受此影响沉积物中重金属含量出现了一段低谷。50年代以后,随着人口的增长、经济的速猛发展,尤其是矿产开发和大规模的水利工程建设,流域水土流失加重,大量陆源物质进入湖泊,使Cu,Ti,Mn,Zn,Co,Fe和Pb含量增加。重金属污染评价结果表明： 100多年来网湖总体上污染较轻,主要污染元素为Pb; Cu和Zn在60年代后出现轻度污染; Mn在沉积物表层出现轻度污染。目前,网湖RI=40.83,生态风险较小,但作为水生生物的养殖基地,中国重要的湿地保护区,其重金属污染问题应引起有关方面的关注,以防患于未然。 相似文献
7.
《Applied Geochemistry》1996,11(4):605-616
Lake Valencia is a tropical lowland lake in north-central Venezuela. Lake bottom sediments were collected from 25 locations in April, 1988. At 2 locations water pH, conductivity, dissolved O2 and temperature were measured at successive depths. After drying, 5 sediment samples were sieved into 5 mechanical fractions. Each was extracted with 1 M HNO3 and analysed for AI, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb and Zn. The <63 μm fraction of all samples was similarly analysed. Water temperatures declined with depth (1°C/25 m) from approximately 26°C. Conductivity varied little with depth but dissolved O2 contents indicated anoxic conditions < 25 m. Water pH (8.8–9.4) was consistent with high dissolved carbonates. There was little consistent relationship between grain size and sediment metal contents. Approximate baseline metal contents were calculated from 21 of 25 samples. The average composition of the sediments corresponded to an ideal mixture of shales/carbonate rocks as 0.5–0.7/0.5-0.3. Five samples from alluvial fans near the mouths of rivers traversing urban-industrial zones had compositions different from the other sediments. Generally, Ph, Zn, Ni, Cd and Cu were anthropogenically enriched by factors of 2–16. The major sources of pollutants were identified as domestic and industrial activities affecting the rivers that traverse the lakeside cities of Maracay and Valencia. Sodium, Mg, Ca, Mn and CO3− showed natural enrichment arising from carbonate precipitation following a physical mixing of 2 sedimentary components (biogenic carbonate and terrigenous material). Low geochemical mobility of metallic elements in neutral-basic and reducing waters, a processes of bury and mixture of sediments and precipitation of carbonate result in only 10% of the lake area being affected by contamination. Isoline plots of elements in the bottom sediments supported a hypothesis that material mixing, physical transport and carbonate precipitation are the main controls of spatial distribution patterns. 相似文献
8.
太湖MS岩芯重金属元素地球化学形态研究 总被引：21，自引：4，他引：17
采用BCR三步提取法对太湖MS岩芯沉积物中Cu、Fe、Mn、Ni、Pb和Zn等6种重金属元素的化学形态进行了研究.结果表明,有效结合态的Cu、Ni和Pb主要以有机物及硫化物结合态、Fe-Mn氧化物结合态存在,Fe和Zn主要以Fe-Mn氧化物结合态存在,Mn主要以可交换态及碳酸盐结合态存在;Fe-Mn氧化物结合态的Ni、Pb和Zn与可还原态的Mn有较好的正相关关系,有机物及硫化物结合态的Cu、Mn、Ni、Pb和Zn与有机碳含量有较好的正相关关系;重金属形态分布体现了重金属元素地球化学性质的差异,以及重金属形态含量与沉积物理化性质的关系.沉积岩芯重金属元素形态垂向变化规律及次生相富集系数表明,Cu、Mn、Ni、Pb和Zn在沉积岩芯13～4 cm有效结合态含量较稳定,为自然沉积;4～0 cm有效结合态含量明显升高,存在一定程度的人为污染.根据137Cs测年结果判断,沉积岩芯Cu、Mn、Ni、Pb和Zn等重金属污染开始于20世纪70年代末期,主要污染元素及污染历史与太湖流域污染工业类型及经济发展阶段相吻合. 相似文献
9.
对拜仁达坝铅锌矿矿集区3个多金属矿区的3个土壤粒级样品中Zn、Pb、Cu、Ag 4种主要成矿元素的7种赋存形式(水溶态、离子交换态、碳酸盐结合态、有机质结合态、铁锰氧化物结合态、硫化物结合态和残渣态)进行了测定。研究结果表明:1银都矿区土壤中Zn、Pb和Ag浓度最高,而道伦达坝矿区土壤中Cu的浓度最高;2拜仁达坝矿集区土壤中Zn、Pb和Cu主要以残渣态形式赋存,而Ag主要以铁锰氧化物结合态和硫化物结合态形式赋存;3拜仁达坝矿集区Zn、Pb和Cu元素在3个土壤粒级中的各个赋存形式所占的比例略有差别,但总体上大致相同,而Ag元素的赋存状态在3个土壤粒级的差异较大;4 3个矿区土壤中水溶态、离子交换态、碳酸盐结合态和有机质结合态的Zn和Pb差别不大;铁锰氧化物结合态、硫化物结合态和残渣态的Zn和Pb,以及Cu和Ag的7个赋存状态在3个矿区的差别较大。 相似文献
10.
厦门西港沉积环境变化及重金属的污染累积 总被引：1，自引：0，他引：1
通过测定柱状沉积物中的重金属、有机碳和硫化物含量, 结合沉积物粒度分析及现代沉积速率, 重现了厦门西港近70a的沉积环境变化及重金属的污染历史, 探讨了沉积环境对重金属累积过程的影响.结果表明, 厦门西港污染指示元素为Cu, Zn, Pb, As, 富集程度依次为As > Cu > Zn > Pb, 元素Cr, Cd和Hg在研究海域内没有富集现象.综观70a来, 厦门西港沉积物组成变化较大, 沉积环境变化明显, 重金属含量的垂向变化特征与当时的水动力、沉积环境变化紧密相关.研究表明, 沉积物来源越稳定, 沉积物粒径越小, 分选性越好, 则沉积物中重金属含量越高; 同时, 各层位的绝大部分重金属与有机碳和硫化物呈显著正相关关系. 相似文献
11.
Partitioning of heavy metals in surface Black Sea sediments 总被引：1，自引：0，他引：1
Bulk heavy metal (Fe, Mn, Co, Cr, Ni, Cu, Zn and Pb) distributions and their chemical partitioning, together with TOC and carbonate data, were studied in oxic to anoxic surface sediments (0–2 cm) obtained at 18 stations throughout the Black Sea. TOC and carbonate contents, and available hydrographic data, indicate biogenic organic matter produced in shallower waters is transported and buried in the deeper waters of the Black Sea. Bulk metal concentrations measured in the sediments can be related to their geochemical cycles and the geology of the surrounding Black Sea region. Somewhat high Cr and Ni contents in the sediments are interpreted to reflect, in part, the weathering of basic-ultrabasic rocks on the Turkish mainland. Maximum carbonate-free levels of Mn (4347 ppm), Ni (355 ppm) and Co (64 ppm) obtained for sediment from the shallow-water station (102 m) probably result from redox cycling at the socalled ‘Mn pump zone’ where scavenging-precipitation processes of Mn prevail. Chemical partitioning of the heavy metals revealed that Cu, Cr and Fe seem to be significantly bound to the detrital phases whereas carbonate phases tend to hold considerable amounts of Mn and Pb. The sequential extraction procedures used in this study also show that the metals Fe, Co, Ni, Cu, Zn and Pb associated with the ‘oxidizable phases’ are in far greater concentrations than the occurrences of these metals with detrital and carbonate phases. These results are in good agreement with the recent studies on suspended matter and thermodynamic calculations which have revealed that organic compounds and sulfides are the major metal carriers in the anoxic Black Sea basin, whereas Fe-Mn oxyhydroxides can also be important phases of other metals, especially at oxic sites. This study shows that, if used with a suitable combination of the various sequential extraction techniques, metal partitioning can provide important information on the varying geological sources and modes of occurrence and distribution of heavy metals in sediments, as well as, on the physical and chemical conditions prevailing in an anoxic marine environment. 相似文献
12.
13.
Huu Hieu Ho Rudy Swennen Val��rie Cappuyns Elvira Vassilieva Tom Van Gerven Tan Van Tran 《Aquatic Geochemistry》2013,19(1):57-75
The speciation and mobility of some selected trace metals (As, Cu, Mn, Pb and Zn) in sediments with depth was investigated in the Cam River-mouth (Vietnam) by collecting sediment cores and analysing porewater and sediment composition, complemented with single (ammonium-EDTA) and sequential (BCR 3-step) extractions and mineralogical analysis (XRD). All trace metals show overall decreasing trends with depth in porewater as a result of anthropogenic input in upper sediment layers. High porewater concentrations of As, Mn and Pb in oxic and suboxic sediment layers may result in groundwater pollution. Sediment-bound Pb and Mn dominate in the reducible and the acid-soluble fraction, respectively, while Cu and Zn distribute rather evenly between four extracted fractions. The porewater metal speciation, as predicted by a geochemical model Visual MINTEQ version 3.0, indicates that the toxicity of Cu, Mn, Pb and Zn (presented by the proportions of free metal ions) decreases with depth, while the toxicity of As increases when As(III) becomes more abundant. The dissolved concentrations of trace metals are not only controlled by the precipitation/dissolution of discrete hydroxide/oxide, carbonate and phosphate minerals, but also by sorption processes on major sorbents (i.e. As on goethite, and Mn and Zn on calcite and dolomite). Sulphide minerals do not show any control even in the anoxic zone most likely because of the low concentration of sulphur. 相似文献
14.
Heavy metal mobility assessment in sediments from the Odiel River (Iberian Pyritic Belt) using sequential extraction 总被引：1，自引：1，他引：0
Rafael Beltrán J. D. de la Rosa J. C. Santos M. Beltrán J. L. Gómez-Ariza 《Environmental Earth Sciences》2010,61(7):1493-1503
The Tessier sequential extraction scheme (SES) was applied to sediments from the Odiel river catchment (Iberian Pyritic Belt,
SW of Spain), one of the most acid rivers on Earth, to assess the chemical association (exchangeable, carbonatic, bound to
manganese and iron oxides, bound to organic matter and residual mineral) of heavy metals (Zn, Cd, Pb, Cu, Cr, Mn, Ni, Fe,
and Hg). Sediments are very heterogeneous in their textural characteristics, showing different grain size. Twenty-seven samples
were studied from from areas along the Odiel River, from the source to the mouth, with special interest in the Odiel Marshes
Natural Park due to its ecological significance. Samples were classified as sandy (especially at the river mouth with low
iron oxide and organic matter content) and clay-silty (in the middle of the river catchment with high iron oxide content).
The numerous sandy samples with low pH values explain the low levels of metals upstream, although potential metals contributions
arise from mining and ore. However, the presence of sulfate in the mining area and carbonate at the mouth may explain the
high presence of lead and iron in these sandy zones. Some percentage of mobile Ni, Cu, and Zn were detected in the mining
area, but the elevated relative percentage of exchangeable Cd in the estuary is even more remarkable. The percentage of Zn
bound to carbonate is considerable in the catchment but especially in the estuary. However, Cu is only detected in the carbonate
phase downstream, in spite of the low concentration of carbonate, which represents a drawback in the application of the Tessier
SES to these types of samples. Finally, relatively high percentages of residual, non-mobile, Hg and Pb were observed, in the
estuarine and mining areas, respectively. Sand, lime, and clay fractions of representative samples from Areas I, II, and III
were used in a metal speciation study. Mainly, the elements analyzed had accumulated in the non-residual fractions. In the
mining area of the Pyrite Belt, the elements analyzed are mainly bound to Fe–Mn oxides (Fe + Mn + Cu + Cr + Pb + Mn ± Zn)
and the organic matter/sulfide fraction (Ni + Zn + Hg ± Cd), independent of sediment grain size. In conclusion, we show that
the results of the study of chemical speciation in sediments from acid rivers are independent of the sediment grain size considered. 相似文献
15.
Application of chemometric methods to analyze the distribution and chemical fraction patterns of metals in sediment from a metropolitan river 总被引：2，自引：2，他引：2
Rivers in metropolitan areas are often highly polluted with materials that pose a threat to a large number of residents. Human
influences lead to contaminants in metropolitan rivers having more complex sources than those in rural rivers. This complexity
results in contamination that is unstable and rapidly changing. Here, the contents and chemical fractionation patterns of
eleven toxic elements (As, Cd, Co, Cu, Cr, Mn, Ni, Pb, Zn, Y, and Hg) were evaluated in 13 samples collected from along the
Beiyunhe River in Beijing, China. The results revealed that the metal contents were unevenly distributed along the river,
with higher levels being observed in the downriver sites and the rendezvous sites. Additionally, more than 80% of the metals
were found to be in the residual phase. The organic and sulfide phases were the most important extractable phases of most
metals, with Ni, Co, Cu, and Cr primarily being associated with these phases and As, Cd, and Zn having a strong association
with the iron/manganese oxide and hydroxide phases. Additionally, Mn was associated with the exchangeable and carbonate phases,
with the lowest concentrations being observed in the organic and sulfide phases. Conversely, the metal exchangeable and carbonate
phases were uniformly distributed throughout the river. Analysis of the metal sources revealed that particles input from the
atmosphere comprised a considerable amount of the metals in the Beiyunhe River. However, these metals likely do not enter
the sediment via atmospheric deposition directly, but rather through rainwater runoff into the river. The methods used in
the present study will be useful in other studies that require analysis of complex data. 相似文献
16.
Two hundred and forty water samples (in four seasons) and seventeen sediment samples have been analyzed to monitor the natural and anthropogenic influences on the water and sediment chemistry of the Dal Lake, Kashmir Himalaya. The scatter diagrams [(Ca+Mg)/total cations (TZ+), (Ca+Mg)/HCO3, (Ca+Mg)/(HCO3+SO4), (Na+K)/TZ+; (Ca+Mg)/(Na+K)] and the geological map of the study area suggest predominance of carbonate and silicate weathering. Lower pH and high total dissolved solids, electrical conductivity and
values in the Gagribal basin and in some patches of other basins reflect anthropogenic inputs in the form of sewage from surrounding population, houseboats, hotels, etc. The Dal Lake is characterized by high chemical index of alteration (CIA: 87–95), reflecting extreme weathering of the catchment area. Relative to the average carbonates, the lakebed sediments are enriched in Al, Ti, Zn, Cu and Co and depleted in Ni and Mn. Compared to the post-Archean Shale the sediments have higher Al, Zn and Cu contents and lower Ni and Co. There are distinct positive anomalies of Al, Mn, Zn and Cu and negative anomalies of Ni and Pb with respect to the upper continental crust. Geoaccumulation index (I
geo) and the US Environmental Protection Agency sediment quality standards indicate that the Gagribal basin and some patches of the Nagin basin are polluted with respect to Zn, Cu and Pb. These data suggest that the Dal Lake is characterized by differential natural and anthropogenic influences. 相似文献
17.
Trace metals (Cd,Pb, Cu,Zn and Ni) in sediment of the submarine pit Dragon ear (Soline Bay,Rogoznica, Croatia) 总被引：1，自引：0，他引：1
Vertical profiles of trace metal (Cd, Pb, Zn, Cu, Ni) concentrations, organic matter content, carbonate content and granulometric
composition were determined in two sediment cores from the submarine pit Dragon Ear (Middle Adriatic). Concentrations of the
analyzed metals (Cd: 0.06–0.12 mg kg−1, Pb: 28.5–67.3 mg kg−1, Zn: 17.0-65.4 mg kg−1, Cu: 21.1–51.9 mg kg−1, Ni: 27.8–40.2 mg kg−1) were in usual range for Adriatic carbonate marine sediments. Nevertheless, concentrations of Cu, Zn, and especially Pb in
the upper layer of sediments (top 12 cm) were higher than in bottom layer, while Cd and Ni concentration profiles were uniform.
Regression analysis and principal component analysis were used to interpret distribution of trace metals, organic matter and
carbonate content in sediment cores. Results of both analysis showed that concentrations of all trace metals in the core below
the entrance to the pit were significantly positively correlated with organic matter and negatively correlated with carbonate,
while in the core more distant from the entrance only Pb showed significant positive correlation with organic matter. Obtained
results indicated that, except for lead which was enriched in surface sediment, in the time of sampling (before the building
of the nautical marina) investigated area belonged to unpolluted areas. 相似文献
18.
Sediment metal profiles were carefully examined for their distribution, chemical fractions, and mobility in three major marine-estuarine
transects in the world’s largest mangrove (Sundarban) ecosystem because anthropogenic influences had been very often noticed.
The level of pollutants was determined by CF and PLI. Metal contents in the freshly deposited sediment of Hugli transect were
relatively high (Pb, Fe, Zn, Mn, Ni, and Co) in comparison to Matla and Saptamukhi due to lithogenic contribution from large
catchments area (8 × 105 km2). Principal component analysis and correlation coefficient revealed that the concentrations of metals were mainly governed
by the variability of the sediment properties. Sediment was subjected to sequential chemical extractions to delineate metal
fractions, namely exchangeable, carbonate, Fe–Mn oxide, organic, and residual. This indicated a valuable insight into the
geochemical mode of the metal retention and their environmental behavior. Single extraction did not help significantly to
explain the metal profiling. 相似文献
19.
Ibtehal Fathy Mohamed 《Arabian Journal of Geosciences》2013,6(11):4145-4153
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
20.
The distribution of Si, Al, Fe, Mn, Cu, Zn, Ni and Cr in different grain-size fractions and geochemical association of Fe,
Mn, Cu and Zn with <63-μm size fraction of bed sediments of Damodar River has been studied. In general, concentrations of
heavy metals tend to increase as the size fractions get finer. However at two sites, near mining areas, the coarser particles
show similar or even higher heavy metal concentrations than finer ones. The higher residence time and/or presence of coarser
particles from mining wastes are possibly responsible for higher metal content in the coarser size fractions. The chemical
fractionation study shows that lithogenic is the major chemical phase for heavy metals. Fe and Mn are the major elements of
the lithogenic lattice, constituting 34–63% and 22–59%, respectively, of total concentrations. Fe-Mn oxide and organic bound
fractions are significant phases in the non-lithogenic fraction. The carbonate fraction is less significant for heavy metal
scavenging in the present environment and shows the following order of abundance Zn>Cu>Mn>Fe. The exchangeable fraction of
the Damodar sediments contains very low amounts of heavy metals suggesting poor bioavailability of metals.
Received: 18 August 1998 · Accepted: 1 December 1998 相似文献