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1.
 The geological setting and landuse activities of the Pimpama River catchment are typical for many drainage systems in southeast Queensland. The river originates in coastal ranges of Late Paleozoic age, crosses a floodplain developed during the Late Pleistocene-Holocene sea-level fluctuations and flows into the southern part of the Moreton Bay. The formation of sedimentary pyrite associated with the mid-Holocene transgression is an important feature of this coastal setting. The oxidation and hydrolysis of pyrite and the consequent production of sulfuric acid are controlled by the amount and seasonality of rainfall and influenced locally by landuse activities. The acid production and the leaching of dissolved metals from river alluvium and estuarine sediments impact substantially on land and aquatic habitats. The water quality of the Pimpama River and its tributaries reflects the lithology of the bedrock and can vary largely depending on season, tidal regimes, sediment lithology, local topography and agricultural activities. Monitoring of river water for several seasons revealed four types of events, each with a different response in terms of water quality: (a) occasional showers during the dry season cause low pH and high amounts of dissolved metals in the water, (b) the first heavy rain of the wet season can produce very toxic conditions (low pH and high concentrations of metals) that can result in a fish kill, (c) towards the end of the wet season, prolonged flushing of pyrite oxidation products leads to short-term recovery of the aquatic system (neutral pH and lower amounts of dissolved metals in the water) and (d) a flood event can produce low pH, salinity and high concentrations of metals, which can represent lethal conditions for aquatic life. Assessment of saturation indexes for representative weathering and oxidation products such as clays, goethite, gibbsite and jarosite shows that these mineral phases can precipitate only when the water reaches neutral pH. Received: 21 September 1998 · Accepted: 1 December 1998  相似文献   

2.
青岛胶州湾沉积物痕量元素黄铁矿化程度及其剖面类型   总被引：4，自引：0，他引：4  
为了探索青岛近海不同沉积环境下不同痕量元素的黄铁矿化规律, 2003年5月潜水员潜入海底采集了4个不同沉积环境的未扰动柱样, 并利用Huerta-Diaz and Morse (1990)连续提取技术测试分析了沉积物痕量金属的不同存在形式(活性态和黄铁矿结合态) 在垂直剖面上的分布规律.结果表明: 除了在涨潮三角洲上部沉积和潮下带沉积物柱子的Cd和Cr外, 痕量元素的黄铁矿化度的增高取决于其相应剖面上的DOP的增高; 并且不同痕量元素向黄铁矿中转移的规模存在着较大的差别, 即元素As、Hg和Mo转移的规模最大, Cu、Zn、Cd、Cr、Co和Ni中等, Pb和Mn最小; 此外, 还进一步揭示了河流三角洲沉积物的下部各元素的黄铁矿化程度高, 而潮下带沉积物以及涨潮三角洲沉积物低.最后指出在河口水下三角洲进行的清淤工作应注意黄铁矿结合态痕量元素的活化而产生生物有效的毒性元素.   相似文献   

3.
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   

4.
Weathering of heavy metal enriched black shales may be one of the most important sources of environmental contamination in areas where black shales are distributed. Heavy metal release during weathering of the Lower Cambrian Black Shales (LCBS) in western Hunan, China, was investigated using traditional geochemical methods and the ICP-MS analytical technique. Concentrations of 16 heavy metals, 8 trace elements and P were measured for samples from selected weathering profiles at the Taiping vanadium ore mine (TP), the Matian phosphorous ore mine (MT), and Taojiang stone-coal mine (TJ). The results show that the bedrock at these three profiles is enriched with Sc, V, Cr, Co, Ni, Cu, Zn, Pb, Th, U, Mo, Cd, Sb, Tl, and P. Based on mass-balance calculation, the percentages of heavy metals released (in % loss) relative to immobile element Nb were estimated. The results show significant rates of release during weathering of: V, Cr, Co, Ni, Cu, Zn, U, Mo, Cd, Sn, Sb, and Tl for the TP profile; Sc, Cr, Mn, Co, Ni, Cu, Zn, Pb, Th, Cd, and Sn for the MT profile; and Sc, Mn, Co, Ni, Zn, Th, Cd, Sn, and Tl for the TJ profile. Among these heavy metals, Co, Ni, Zn, Cd, and Sn show very similar features of release from each of the three weathering profiles. The heavy metals released during weathering may affect the environment (especially topsoil and surface waters) and are possibly related to an observed high incidence of endemic diseases in the area.  相似文献   

5.
Urbanisation and industrial development lead to contamination of estuaries and streams with dispersed loadings of heavy metals and metalloids. Contributions of these elements also occur from natural sources. This study provides baseline geochemical data on the respective natural and anthropogenic inputs of Cu, Pb, Zn, Cd, As, Sb, Cr, Ni, Mn and S to estuarine, fluvial and wetland sediments, and adjacent soils, in the Kooloonbung Creek catchment that drains the Port Macquarie urban area in north coastal New South Wales. There have been anthropogenic additions of Cu, Pb, Zn and As from dispersed urban sources at Port Macquarie, but they are restricted to the local catchment and do not impact on the adjacent Hastings River estuary. The most contaminated sediments display enrichment factors up to 20 × for Cu and Pb, 9 × for Zn and 5 × for As relative to local background values. However, only one value (for Pb) exceeds National Water Quality Management Strategy interim sediment quality guideline (high) values. On the other hand, sediments and local soils are commonly strongly enriched in Cr, Ni and Mn, reflecting adjacent ultramafic and mafic rock substrate and lateritic regolith. Concentrations of Cr and Ni are commonly well above interim sediment quality guideline (high) values for sediments, but are in mineralogical forms that are not readily bioavailable. Sediment and soil quality guideline values consequently need to recognise natural enrichments and the mineralogical siting of heavy metals. Although dissolved concentrations of heavy metals in stream waters are commonly low, there is evidence for mobility of Cu, Zn, Fe and Al. Parts of the Kooloonbung Creek wetland area lie on sulfidic estuarine sediments (potential acid sulfate soils). Experimental oxidation of uncontaminated and contaminated sulfidic sediments leads to substantial dissolution of heavy metals under acid conditions, with subsequent aquatic mobility. The results warn about disturbance and oxidation of potential acid sulfate soils that have been contaminated by urban and natural heavy-metal sources.  相似文献   

6.
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   

7.
Heavy metal concentrations in floodplain surface soils, Lahn River, Germany   总被引：2，自引：0，他引：2  
 Even relatively pristine drainage basins in industrial countries would appear to have received anthropogenic inputs of heavy metals. Investigation of floodplain surface soils in the Lahn River drainage basin, west-central Germany, indicates that the Cu concentration is 1.5 times the pre-industrial level, Pb and Zn contents twice the pre-industrial level; Cd, Co, and Cr concentrations are nearly equal to background metal values. Based on contamination standards developed for the Lahn River, floodplain soils are moderately contaminated with Pb and Zn, slightly contaminated with Cu. Metal contents are uniform across the floodplain, with the exception of a peak immediately adjacent to the Lahn River. Floodplain surface soil metal contents are less in the Lahn River basin than in larger drainage systems of Germany. Although Lahn River metalliferous sediments are presently immobile, they would, if eroded, contribute to downstream heavy metal concentrations. Consequently, metal storage in smaller drainage basins such as the Lahn should be considered in predictions of future metal loads in major river systems, for aggregate small basins could serve as significant metal contributors. Received: 21 August 1995 · Accepted: 23 January 1996  相似文献   

8.
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   

9.
《Applied Geochemistry》2004,19(11):1837-1853
Iron monosulfide formation and oxidation processes were studied in the extensively drained acid sulfate soil environment of the Tweed River floodplain in eastern Australia. Porewater profiles of pH, Eh, SO42−, Fe2+, Fe3+, Cl−, HCO3−, and metals (Cd, Co, Cr, Cu, Ni, Pb and Zn) were obtained using in situ dialysis membrane samplers (`peepers'). Concentrations of acid volatile S (AVS), pyrite, total S, reactive Fe, total and organic C, simultaneously extracted metals (SEMs) and total elemental composition by X-ray fluorescence, were determined on sediment samples. The oxidation of pyrite in the surrounding landscape provides a source of acidity, Fe, Al, SO4 and metals, which are exported into the drainage system where they accumulate in the sediments and porewaters. Negative porewater concentration gradients of SO42− and Fe2+, and large AVS concentrations in the sediments, indicate Fe monosulfides form rapidly under reducing conditions and consume acidity and metals. Oxidation of the sediments during previous drought episodes has resulted in the conversion of monosulfides and pyrite to oxidised Fe minerals and the release of acidity, SO42−, Fe3+, and metals to the surface waters. These formation and oxidation cycles show that Fe monosulfides play an important role in controlling water quality in the drainage system.  相似文献   

10.
 The concentrations of various metals (Cr, Cu, Co, Fe, Mn, Ni, Pb, Zn, and Cd) were determined in recently deposited surface sediments of the Gomati River in the Lucknow urban area. Markedly elevated concentrations (milligrams per kilogram) of some of the metals, Cd (0.26–3.62), Cu (33–147), Ni (45–86), Pb (25–77), and Zn (90–389) were observed. Profiles of these metals across the Lucknow urban stretch show a progressive downstream increase due to additions from 4 major drainage networks discharging the urban effluents into the river. The degree of metal contamination is compared with the local background and global standards. The geoaccumulation index order for the river sediments is Cd>Zn>Cu>Cr>Pb. Significant correlations were observed between Cr and Zn, Cr and Cu, Cu and Zn and total sediment carbon with Cr and Zn. This study reveals that the urbanization process is associated with higher concentrations of heavy metals such as Cd, Cu, Cr, Pb, and Zn in the Gomati River sediments. To keep the river clean for the future, it is strongly recommended that urban effluents should not be overlooked before their discharge into the river. Received: 16 February 1996 · Accepted: 29 February 1996  相似文献   

11.
A presentation is made of the study of an underground polymetallic sulphide mine and the pollution caused by this in the adjoining aquatic ecosystems. Troya Mine is in the Basque Cantabrian region (northern Spain). The annual production of the ore deposit of over 3.7 million tons of Pb (0.9%), Zn (11.2%) and Cu (0.2%) was 300,000 t. It was open and producing from 1986-1993. The mineralization was made up of pyrite, marcasite, sphalerite, galena, chalcopyrite and arsenopyrite. Only the Zn and the Pb were mined. We studied the distribution and behaviour of the heavy metals Zn, Pb, Fe, Mn, Cu, Cr and Cd in the water column, dissolved and suspended fractions, and in the sediments of Estanda Stream and of Gezala Creek. Zn, Cd and Mn tend to be found in the water; Fe, Pb, Cu and Cr appear as an adsorbed fractionin the solid phases. Those of the second group are significantly linked to the fluvial sediments and present very high levels. The concentrations of the metals are conditioned by the waters from the mine galleries, by the leached waste, by the surface runoff, and by overflow from the spillway of the tailings pond. Our observations provide knowledge on the extent of the polluting power of the metals, the physico-chemical effects in play and the subsequent chances of recovering these highly affected environments.  相似文献   

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

13.
This study provided a picture of the spatial and temporal distributions of Cr, Co, Ni Cu, Zn, As, Cd and Pb in bottom sediments of Tolo Harbour. The concentrations of the eight heavy metals differed significantly between sites due to the poor tidal flushing in Tolo Harbour. The levels of Cu, Zn, Cd and Pb were generally enriched in sediments from inner Tolo Harbour, while sediments from outer Tolo Harbour (Tolo Channel) had higher levels of Cr, Co and Ni. The redox sensitive element arsenic showed no distinct spatial pattern in Tolo Harbour. The decreasing levels of Cu, Zn, Pb and Cd in sediments with increasing distance from land demonstrated a typical diffusion pattern from land to the direction of sea. Two hot spots of Cu, Zn, Pb and Cd in sediments were located near Tai Po and Sha Tin new town, indicating that Cu, Zn, Pb and Zn were from land-derived sources. The sites with relatively high levels of Cr, Co and Ni in sediments were located in areas close to waste spoil in sea floor. The natural and anthropogenic inputs from Sha Tin and Tai Po to Tolo Harbour were mostly responsible for Cu, Zn, Cd and Pb enrichment in sediments from inner Tolo Harbour. The waste spoil in sea floor was believed to contribute to the Cr, Co and Ni in outer Tolo Harbour. The results of correlation coefficient between the eight heavy metals showed that Cu, Zn, Cd and Pb were strongly positively correlated, and Cr, Co and Ni were also significantly correlated with each other. The best explanation of strong correlation was their similar source. As, however, is not well correlated with the other seven heavy metals. The average concentrations of Cu and Zn displayed general increasing trends from 1978 to 2006 in Tolo Harbour, while the mean levels of Cr and Pb displayed a substantial decrease from 1978 to 1987, then a slight increase after 1987. No distinct temporal trends of the concentrations of Ni and As were observed from 1978 due to the inconsecutive data. On the other hand, the increasing trends of Cr, Cu, Zn, Cd and Pb were observed since 1996.  相似文献   

14.
River waters play a significant role in supplying naturally- and anthropogenically-derived materials to Lake Qinghai, northeastern Tibetan Plateau. To define the sources and controlling processes for river water chemistry within the Lake Qinghai catchment, high precision ICP-MS trace element concentrations were measured in water samples collected from the Buha River weekly in 2007, and from other major rivers in the post-monsoon (late October 2006) and monsoon (late July 2007) seasons. The distributions of trace elements vary in time and space with distinct seasonal patterns. The primary flux in the Buha River is higher TDS and dissolved Al, B, Cr, Li, Mo, Rb, Sr and U during springtime than those during other seasons and is attributed to the inputs derived from both rock weathering and atmospheric processes. Among these elements, the fluxes of dissolved Cr, B and Rb are strongly influenced by eolian dust input. The fluxes of dissolved Li, Mo, Sr and U are also influenced by weathering processes, reflecting the sensitivity of chemical weathering to monsoon conditions. The anthropogenic sources appear to be the dominant contribution to potentially harmful metals (Ni, Cu, Co, Zn and Pb), with high fluxes at onset of the main discharge pulses due, at least partially, to a runoff washout effect. For other major rivers, except for Ba, concentrations of trace elements are higher in the monsoon than in the post-monsoon season. A total of 38.5 ± 3.1 tons of potentially harmful elements are transported into the lake annually, despite human activities within the catchment being limited. Nearly all river water samples contain dissolved trace elements below the World Health Organization guidelines for drinking water, with the exception of As and B in the Daotang River water samples collected in late July probably mobilized from underlying lacustrine sediments.  相似文献   

15.
In order to assess the pollution levels of selected heavy metals, 45 bottom sediment samples were collected from Al-Kharrar lagoon in central western Saudi Arabia. The concentrations of the heavy metals were recorded using inductively coupled plasma-mass spectrometer (ICP-MS). The results showed that the concentrations of Pb and Cd exceeded the environmental background values. However, the heavy metal contents were less than the threshold effect level (TEL) limit. The concentrations of heavy metals in lagoon bottom sediments varied spatially, but their variations showed similar trends. Elevated levels of metals were observed in the northern and southern parts of the lagoon. Evaluation of contamination levels by the sediment quality guidelines (SQG) of the US-EPA revealed that sediments were non-polluted-moderately to heavily polluted with Pb; non-polluted to moderately polluted with Cu; and non-polluted with Mn, Zn, Cd, and Cr. The geoaccumulation index showed that lagoon sediments were unpolluted with Cd, Mn, Fe, Hg, Mo, and Se; unpolluted to moderately polluted with Zn and Co; and moderately polluted with Pb, Cr, Cu, and As. The high enrichment factor values for Pb, As, Cu, Cr, Co, and Zn (>2) indicate their anthropogenic sources, whereas the remaining elements were of natural origins consistent with their low enrichment levels. The values of CF indicate that the bottom sediments of Al-Kharrar lagoon are moderately contaminated with Mn and Pb.  相似文献   

16.
The concentration and areal distribution of selected metals (Pb, Zn, Cu, Cd, Ni, Fe, and Cr) in the sediments of the Calabar River were studied to determine the extent of anthropogenic input and to estimate the effects of dumping industrial waste materials into the river. The concentrations of Pb, Zn, and Cu indicate relatively moderate pollution mainly on the left-hand side of the river while Ni, Cr, Co, Cd, and Fe levels are below values found to have adverse effects on the lives of marine biota. High metal contents are found close to industrial establishments and so enhanced metal concentrations are related to industrial sewage and metal leaching from garbage and solid waste dumps.  相似文献   

17.
This work reports a geochemical study of sediments from the upper Paracatu River Basin. The objective is to define the influences of Au, Zn, and Pb mineral deposits and mining activities on the sediment metal sources, distribution, and accretion. The samples were analyzed using ICP/OES, AAS, and XRD techniques and were treated with principal components analysis and the geo-accumulation index. The main geochemical processes that control the sediment composition are pyrite oxidation, muscovite weathering, carbonate dissolution, and the erosion of oxisols enriched with Zn and Pb. The upper Rico Stream has high Al, Fe, Cu, Cr, Co, and Mn concentrations due erosion of oxisols and pyrite oxidation and muscovite alteration present in the parental rock. The artisanal alluvial gold mining increased the primary rock-minerals?? weathering and Hg sediment concentration. The lower Escuro River and Santa Catarina Stream are enriched with Zn and Pb due the erosion of metal-rich soils formed over galena, sphalerite, calamine, and willemite mineral deposits located upstream. Elements such as Ca, Mg, and Ba have low concentrations throughout the sampled area due the high solubility of these metals-bearing minerals. The dispersion of metals is limited by the basin geomorphology and their affinity to silt-clayey minerals and Fe and Mn oxides and hydroxides in circumneutral pH waters.  相似文献   

18.
To evaluate muck sediments as a potential soil amendment, total and Mehlich III-extractable concentrations of Cd, Cu, Cr, Ni, Pb, Zn, and Co in 59 muck sediment samples from the St. Lucie Estuary were analyzed. A seven-step chemical fractionation procedure was used to assess the potential mobility of heavy metals. Except for Cd, the average total concentrations of the metals are lower than the reported average concentrations of these elements in municipal composts in the U.S.A. The concentrations were also below critical levels for the safe use of wastes and byproducts in agriculture, as established by the United States Environmental Protection Agency. The Cd, Cu, Cr, Ni, Pb, Zn and Co in the sediments were predominantly associated with silicate minerals in the residual form. Most metals in the muck sediments occur predominantly in weakly mobile or nonbioavailable forms. Use of mucks in neutral pH upland soils should not pose any significant hazards or risk to the environment. However, Cd, Cu, Cr, Ni, Pb, Zn, and Co, especially Zn, Cu, and Pb, could be more readily released from the muck sediments under acidic soil conditions.  相似文献   

19.
Cu, Zn, Ni, Cr and Co pollution of El Melah lagoon waters near the city of Slimane in northwestern Tunisia was evaluated relative to identified human activity and waste repositories in the neighborhood. These metals were measured in lagoon waters and sediments, and in the potential pollutants, during two consecutive years for evaluation of their impact on the lagoon waters. A sequential extraction of the metals from sediments was designed to distinguish those potentially anthropogenic from those naturally scavenged by the sediments. This procedure allowed identification and quantification of the metals that are temporarily trapped, therefore contributing directly to the ecotoxicity of the lagoon waters, from those incorporated in the sediments. The highest supplies of Cr and Co to the lagoon waters come from El-Bey creek waters, while the wastewater treatment plant contributes for most of the Zn, and the urban garbage deposit for most of the Ni. Alternatively, the impact of the cultivated soils is minimal for the studied metals. In fact, Zn and Ni contents of the sediments amount 100 to 20 times less than in the present water, which is negligible. Cr is potentially the most polluting with contents up to ten times more in the sediments of the eastern lagoon pool and next to the outlet of the wastewater plant than in the waters. Potentially, contents of the anthropogenic Cu of the sediments amount 3–15 times less than in the lagoon waters.  相似文献   

20.
The mineralogy and geochemistry of the waste rocks distributed at Taojiang Mn-ore deposit, central Hunan province, China, were studied using X-ray powder diffraction (XRD), electron microprobe analysis (EMPA) fitted with energy dispersive spectrometer (EDS) and inductively coupled plasma mass spectrum (atomic emission spectra) ICP-MS (AES), with the aim of predicting the environmental impacts of weathering of the waste rocks. The mineralogical results from microscope observation and XRD and EMPA studies show that the waste rock is composed of black shale and minor Mn carbonates. The oxidation of sulfide minerals such as galena, pyrite and chalcopyrite is accompanied by decomposition of Mn carbonates and K-feldspar during exposure to atmospheric O2. The geochemical characteristics of major, rare earth elements (REE) and trace elements of the waste rocks also show that the waste rock can be divided into black shale and Mn carbonate, and both of them are currently under chemical weathering. The major alkalies and alkaline elements (Ca, Mg, Na, K, Rb, Sr and Cs) and major elements (Fe, S and P) and heavy metals (Sc, V, Cr, Th, U, Sn, Co, Ni, Cu, Zn, Pb, Mo, Cd, Sb, an Tl) are being released during weathering. The mobility of alkalis and alkaline elements Ca, Mg, Na, K, Rb, Sr and Cs is controlled by decomposition of Mn carbonates. The dispersion of Cr, Sc and Th (U) might be related to weathering of K-feldspar, and the release of the heavy metals Co, Ni, Cu, Zn, Pb, Mo, Cd Sb and Tl is dominated by the breaking of sulfide minerals. The REE of the waste rocks and surrounding soils and the spidery distribution patterns of heavy metals in the waste rocks, the surrounding soils and the surface waters show that weathering of the waste rocks and bedrock might be the sources of heavy metal contamination for the surrounding soils and surface water system for the mining area. This is predicted by the mass-balance calculation by using Zr as an immobile element. Therefore, it is urgently necessary take measures to treat the waste rocks distributed throughout the area for the local environmental protection.  相似文献   

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