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1.
Concentrations of Co, Cu, Pb and Zn were determined in 107 surficial sediment samples from the continental margin adjacent to Sydney, Australia. The spatial distributions of trace metals in the sediments and the mud content are similar and increase with greater distance from the coast. In contrast, normalization of the concentrations of Cu, Pb and Zn in the total sediment with Co enables a coastal anthropogenic source to be identified. The spatial distribution of Co-normalized concentrations of Cu, Pb and Zn in total sediment is similar to the distribution of these trace metals in the fine fraction of sediment (<62.5 microm), indicating that Co may be used as a normalizing element for determining contaminant sources in the marine environment near Sydney.  相似文献   

2.
An assessment of metal contamination in coastal sediments of the Caspian Sea   总被引：11，自引：0，他引：11  
An assessment of marine pollution due to metals was made in the Caspian Sea based on coastal sediment collected in Azerbaijan, Iran, Kazakhstan, Russia and Turkmenistan. Despite the high carbonate content, the distribution of most metals was largely controlled by terrigenous inputs. Several metals (As, Cr, Ni) exhibited concentrations that exceed sediment quality guidelines. Such metals have a high natural background but anthropogenic activities, notably mining, may further enhance concentrations. This would explain hot spots for Cu and Zn in Azerbaijan and Iran, and Cr at the mouth of the Ural River in Kazakhstan. Contamination by Hg was observed to the south of Baku Bay, Azerbaijan. Some anomalously high concentrations of Ba in the central Caspian are probably from offshore drilling operations, but the elevated U concentrations (up to 11.1 microg g(-1)) may be natural in origin. Several metals (Ag, Cd, Pb) have relatively low levels that pose no environmental concerns.  相似文献   

3.
Suspended sediment adsorbs pollutants from flowing water in rivers and deposits onto the bed. However, the pollutants accumulated in the river bed sediment may affect the bio-community through food chain for a long period of time. To study the problem the concentration of heavy metals （Cr, Cd, Hg, Cu, Fe, Zn, Pb and As） in water, sediment, and fish/invertebrate were investigated in the middle and lower reaches of the Yangtze River during 2006-2007. The concentrations of heavy metals were 100-10,000 times higher in the sediment than in the water. Benthic invertebrates had relatively high concentrations of heavy metals in their tissues due to their proximity to contaminated sediments. Benthic invertivore fish had moderately high concentrations of heavy metals whereas phytoplanktivore fish, such as the silver carp, accumulated the lowest concentration of heavy metals. The concentrations of Cu, Zn, and Fe were higher than Hg, Pb, Cd, Cr, and As in the tissue samples. The concentration of heavy metals was lower in the river sediments than in the lake sediments. Conversely, the concentration of heavy metals was higher in river water than in lake water. While a pollution event into a water body is often transitory, the effects of the pollutants may be long-lived due to their tendency to be absorbed in the sediments and then released into the food chain. The heavy metals were concentrated in the following order： bottom material 〉 demersal fish and benthic fauna 〉 middle-lower layer fish 〉 upper-middle layer fish 〉 water.  相似文献   

4.
Mangroves have been observed to possess a tolerance to high levels of heavy metals, yet accumulated metals may induce subcellular biochemical changes, which can impact on processes at the organism level. Six month-old seedlings of the grey mangrove, Avicennia marina (Forsk.) Vierh, were exposed to a range of Cu (0-800 micrograms/g), Pb (0-800 micrograms/g) and Zn (0-1000 micrograms/g) concentrations in sediments under laboratory conditions, to determine leaf tissue metal accumulation patterns, effects on photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids), and the activity of the antioxidant enzyme peroxidase. Limited Cu uptake to leaves was observed at low sediment Cu levels, with saturation and visible toxicity to Cu at sediment levels greater than 400 micrograms/g. Leaf Pb concentrations remained low over a range of Pb sediment concentrations, up to 400 micrograms/g Pb, above which it appeared that unrestricted transport of Pb occurred, although no visible signs of Pb toxicity were observed. Zn was accumulated linearly with sediment zinc concentration, and visible toxicity occurring at the highest concentration, 1000 micrograms/g Zn. Significant increases in peroxidase activity and decreases in photopigments were found with Cu and Zn at concentrations lower than those inducing visible toxicity. Significant increases in peroxidase activity only, were found when plants were exposed to Pb. Positive linear relationships between peroxidase activity and leaf tissue metal concentrations were found for all metals. Significant linear decreases in photosynthetic pigments with increasing leaf tissue metal concentrations were observed with Cu and Zn only. Photosynthetic pigments and peroxidase activity may be applicable as sensitive biological indicators of Cu and Zn stress, and peroxidase activity for Pb stress in A. marina.  相似文献   

5.
In order to investigate the pollution levels, sources and ecological risks of arsenic (As) and heavy metals (Cr, Ni, Cu, Zn, Pb and Cd) in inshore sediments of the Yellow River estuary, the surface sediment in areas of inshore coastal waters were sampled in October 2014 as the flow-sediment regulation project (FSRP) was implemented for 13 years. Results showed that the concentrations of As and heavy metals in inshore sediments of the Yellow River estuary were in the order of Zn?>?Cr?>?Cu?>?Ni?>?Pb?>?As?>?Cd. Higher levels of As, Cr, Ni, Cu, Zn and Pb generally occurred in fine-grained sediments of the Yellow River estuary and the southeast region, which was consistent with the spatial distribution of clay. In contrast, higher concentrations of Cd were generally observed in northwest area of the Yellow River estuary and near the Qingshuigou estuary, which showed similarly spatial distribution with that of sand. The sediment quality guidelines (SQGS) and geoaccumulation indices (Igeo) indicated that the inshore sediments were polluted by Cu, Cd, As, Pb and Zn, and, among them, Cd pollution was more serious. Ecological risk indices (E r i ) demonstrated low risks for Cr, Ni, Cu, Zn, Pb and As, and high potential toxicity by Cd. The integrated ecological risk index implied that 6.8% of stations presented moderate risk, 4.5% of stations exhibited disastrous risk, and 88.7% of stations demonstrated considerable risk. Principal component analysis indicated that Ni, Cu, Zn, Pb and As might originate from common pollution sources, while Cr and Cd might share another similar sources. With the continuous implementation of FSRP, As and heavy metal levels in inshore sediments of the Yellow River estuary could be classified as stage I (2002–2010) and stage II (2010–2014). In the stage I, As, Cr, Ni, Cu, Zn and Pb levels fluctuated but decreased significantly, whereas Cd concentrations showed little variation. In the stage II, As and heavy metal levels significantly increased although some little fluctuations occurred. The continuous accumulation of As and heavy metals (especially for Cd) in inshore sediments of the Yellow River estuary would occur again as the FSRP was implemented for 9 years (since 2010). The ecotoxicological risk of Cd, As, Ni and Cu in inshore sediments might be more serious since the accumulation of the four elements would be continuously occurred in future years. Next step, there will be long-term potential consequences for marine organism if effective measures are not taken to control the loadings of metal pollutants into estuary.  相似文献   

6.
Sediment loadings and leaf accumulation of the heavy metals copper (Cu), lead (Pb) and zinc (Zn) with accompanying changes in leaf chlorophylls' (a + b), carotenoids and the antioxidant enzyme peroxidase were examined in the grey mangrove Avicennia marina (Forsk.) Vierh, in order to determine the applicability of these parameters as biomarkers of heavy metal stress under field conditions. Copper was found to show limited accumulation to leaf tissue, following a linear relationship at lower sediment concentrations, with saturation at higher sediment Cu concentrations. Copper accumulation relationships to leaf tissue were maintained temporally, and increases in sediment Cu, salinity, and decreases in sediment pH and Zn contributed to the accumulation of Cu to leaf tissue. Lead showed a significant relationship between sediment and leaf Pb levels, but accumulation was minimal. Accumulation relationships for Pb were not maintained temporally, and high sediment Pb, low pH and organic content increased bioavailability and accumulation of Pb. Zinc was the most mobile of all metals and was accumulated to the greatest quantities in leaf tissue in a dose-dependant relationship. Some temporal variation in Zn accumulation occurred, and higher sediment pH, organic content Zn and Pb promoted leaf Zn accumulation. Leaf Cu and Zn showed the strongest relationship with peroxidase activity and to a lesser degree Pb. Zinc was the only accumulated metal to show relationship maintenance with peroxidase activity over time. It was found that peroxidase activity best reflects the total phytotoxic effect from the combined metal stress of all three accumulated leaf metals. The only significant photopigment relationship evidenced was that of leaf Zn with the chlorophyll a/b ratio, but was not maintained temporally. Peroxidase activity may be an appropriate biomarker for Zn or total metal accumulation in leaf tissue, and the chlorophyll a/b ratio a suitable biomarker of Zn accumulation though requires temporal monitoring under field conditions.  相似文献   

7.
In the joint estuary of the Odiel and Tinto rivers (SW Spain), the invasive Spartina densiflora Brongn. and the native Spartina maritima (Curtis) Fernald are growing over sediments with extreme concentrations of heavy metals. The contents of As, Cu, Fe, Mn, Pb and Zn were determined in sediments, rhizosediments and different tissues of both species, from Odiel and Tinto marshes. S. densiflora showed a higher capability to retain metals around their roots and to control the uptake or transport of metals, mediated by a higher formation of plaques of Fe/Mn (hydro) oxides on the roots. At the Tinto marsh, there were no differences between the metal concentrations of the sediment and those of the rhizosediment, a fact that could be explained by the extremely high concentrations of metals which can pass over a threshold value, altering the properties of root cells and preventing roots from acting as a ‘barrier’ to the uptake or transport of metals.  相似文献   

8.
洞庭湖沉积物中重金属污染特征与评价   总被引：31，自引：2，他引：29  
于2003-2004年在洞庭湖湖区采集沉积物样品700个,测定了沉积物中As、Cd、Cr、Cu、Hg、Ni、Pb、Zn的含量,并用地积累指数方法和主成分分析法对沉积物中的重金属污染状况进行了评价和分析.结果显示,洞庭湖各子湖区沉积物中Cd、Cr、Cu、Pb、zn的平均含量都属于国家土壤二级标准,AB、Hg、Ni属于国家土壤一级至二级土壤标准;在南洞庭湖与东洞庭湖人湖河流的三角洲的前缘是沉积物重金属积累最高的地点,而在西洞庭湖入湖河流三角洲的后缘沉积物重金属含量比前缘高.采用综合地积累指数法对洞庭湖各子湖区沉积物进行评价,结果表明:南洞庭湖(重污染)>东洞庭湖(偏重污染)>西洞庭湖(中度污染)>大通湖(中度污染)>城陵矶(轻度污染).采用主成分分析法对洞庭湖各子湖区沉积物进行分析,结果表明:南洞庭湖与东洞庭溯第一主成分贡献率分别为55.22%、56.86%,主要支配AS、Cd、Hg、Pb、zn的载荷,而第二主成分贡献率分别为30.04%、33.11%主要支配Cu、Cr、Ni的载荷:西洞庭湖、大通湖和城陵矶因沉积物重金属来源不同,主成分分析结果相差较大.  相似文献   

9.
Laboratory incubation experiments were carried out on sediment cores collected from Esthwaite Water, U.K., during April 1987, when the sediments displayed a characteristic surface (1.5 to 2 cm) oxide floc. The experiments were undertaken at 10°C, in the dark, under variable redox and pH conditions for periods of ~ 720 h (30 d). In some cases, realistic amounts of decomposing lake algae were added to simulate the deposition of an algal bloom. Pore waters and overlying waters were obtained from the incubated sediment cores at various time intervals and the samples analysed for pH and dissolved Fe, Mn, Zn and Cu by AAS. The results demonstrated that trace metal concentrations at the sediment-water interface can show rapid, pulsed responses to episodic events associated with controlling factors such as algal deposition and mixing conditions. The variations in dissolved Fe and Mn concentrations could generally be explained by their well known redox behaviour. Appreciable loss of Mn from solution under conditions of well-developed anoxia was consistent with adsorption of Mn2+ by FeS. Cu and Zn were both rapidly (24 h) released into solution during incubation of sediment cores prior to the development of anoxia in the overlying waters. Their most likely sources were the reductive remobilization of Mn oxides and the decomposition of organic matter. The addition of decomposing algae to a series of cores resulted in even higher interfacial dissolved concentrations of Cu and Zn, probably through acting as a supplementary source of the metals and through increased oxide dissolution. Switching from anoxic to oxic conditions also rapidly increased dissolved Cu and Zn concentrations, possibly due to their release during the oxidation of metal sulphides. The enhanced releases of dissolved Cu and Zn were generally short-lived with removal being attributed to the formation of sulphides during anoxia and to adsorption by Fe and Mn oxides under oxic conditions.  相似文献   

10.
Antifouling paint residues collected from the hard-standings of a marine leisure boat facility have been chemically characterised. Scanning electron microscopy revealed distinct layers, many containing oxidic particles of Cu and Zn. Quantitative analysis indicated concentrations of Cu and Zn averaging about 300 and 100 mg g−1, respectively, and small proportions of these metals (<2%) in organometallic form as pyrithione compounds. Other trace metals present included Ag, Cd, Cr, Ni, Pb and Sn, with maximum concentrations of about 330, 75, 1200, 780, 1800 and 25,000 μg g−1, respectively. Estuarine sediment collected near a boatyard contained concentrations of Cu and Zn an order of magnitude greater than respective concentrations in “background” sediment, and mass balance calculations suggested that the former sample was contaminated by about 1% by weight of paint particles. Clearly, antifouling residues represent a highly significant, heterogeneous source of metallic contamination in the marine environment where boating activities occur.  相似文献   

11.
抚仙湖沉积物重金属时空变化与人为污染评价   总被引：11，自引：3，他引：8  
分析了抚仙湖表层沉积物及沉积短岩芯中10种金属元素含量,结合沉积年代学,定量研究了Cr、Cu、Ni、Pb、Zn的污染特征及时空变化规律;参考沉积物质量基准与潜在生态风险指数法探讨了表层沉积物重金属的潜在生态风险.结果表明,表层沉积物中重金属含量具有一定的空间差异性,近岸地区重金属含量总体上高于湖心区;Pb、Zn含量自1980s中期以来逐渐增加,而Cr、Cu、Ni含量呈下降趋势.重金属富集系数与聚类分析结果表明,抚仙湖沉积物主要重金属污染元素为Pb、Zn,污染开始于1980s中期,并逐渐加重.表层沉积物中Pb、Zn富集系数分别为1.6~4.1和1.4~2.6,已达到弱—中等污染程度,北部湖区污染程度略高于南部湖区;除此之外,北部湖区近岸区域Cr污染程度也略高于其他湖区.除了大气沉降来源之外,抚仙湖沉积物重金属污染还可能与入湖河流输入有关.单因子生态风险指数表明,表层沉积物中Cr、Cu、Ni、Pb、Zn具有较低的潜在生态风险;而综合潜在生态风险指数表明,表层沉积物中重金属具有中等程度的潜在生态风险,这与根据沉积物质量基准所获得的评价结果一致.  相似文献   

12.
Concentration of 7 heavy metals, Zn, Fe, Cu, Cr, Cd, Pb and Ni in mudflat sediments, mangrove root sediments and root tissues of Acanthus ilicifolius, Aegicerus corniculatum and Kandelia candel from the Mai Po Nature Reserve, Northwest Hong Kong, were measured. Metal concentrations in the upper 0–10 cm of the sediment cores from the mudflat were 4–25% higher than those found in the bottom 21–30 cm. Relative Topsoil Enrichment Index approximated 1.0 for all the metals. Mudflat sediment concentrations of Fe, Ni, Cr, Cd and Cu were greater than those found in the mangrove sediments. Except for Fe, concentrations of the other 6 heavy metals were more elevated in the mangrove root sediments than in the corresponding root samples. Higher concentration factors for Zn, Fe and Cu may indicate bioaccumulation. Mean metal concentrations in both mudflat and mangrove sediments decreased in the order Fe > Zn > Pb > Ni > Cu > Cr > Cd. Mangrove root tissues also showed the same pattern except that Pb > Cu > Ni  相似文献   

13.
Freshwater lakes are one of the most vulnerable ecosystems to environmental contamination. This study was initiated to assess the spatial distribution, fractionation, ecological risk of selected potentially toxic metals (Pb, Zn, Cu, Cr, and Ni) in bottom sediments of the Zarivar lake, the second largest freshwater lake in Iran. The results revealed that Pb, Zn and Cu had the high spatial variability (coefficient of variation >50) across the sampling sites and their maximum concentrations (197.5 for Pb, 198.7 for Zn and 185.6 mg/kg for Cu) were observed in sampling sites from the northern, western and eastern margins of the lake. Cr and Ni with average concentrations of 28.3 and 31.38 mg/kg respectively, exhibited low spatial variability (coefficient of variation <20) and their concentrations did not vary significantly among the sampling sites. Based on the redundancy analysis (RDA), sediment organic matter was strongly correlated with Pb, Zn and Cu while Fe2O3 and Al2O3 showed a positive correlation with Ni and Cr. The calculated average enrichment factor (EF) and geoaccumulation index (Igeo) showed that the contamination level of metals can be arranged in the following order of Pb> Cu > Zn > Cr > Ni. Results from the modified five-step sequential extraction analysis indicated that 40 % of total Pb and Zn were associated with the reducible fraction, 45 % of Cu with the oxidizable fraction and more than 80 % of total Ni and Cr were retrieved from the residual fraction. It was also noticed that Pb, Zn and Cu were more incorporated into the non-residual fractions in the sites with a higher total concentration of these metals, suggesting that both total concentration and fractionation behavior of metals were influenced by their potential sources in the study area. Ecological risk assessment using the potential ecological risk index (PERI) and the modified potential ecological risk index (MPERI) showed that sediments from the eight sampling sites pose a moderate to considerable risk whereas the other sites had low ecological risk level. In comparison to sediment quality guidelines (SQGs), the effects range low (ERL) and probable effect level (PEL) values for Pb, Cu and Zn were exceeded at some sampling sites while Ni and Cr concentrations were found to be below or close to their SQGs values at all the sampling sites. Pb was generally identified as the contaminant of most concern in the study area. Taking into account the results obtained from the fractionation study and the source contribution estimate, it can be inferred that the Pb, Zn and Cu with the average contribution of 79, 54 and 64 % respectively, were mainly derived from anthropogenic sources whereas Ni and Cr with the estimated contribution of 80 and 89 % were predominately from the lithogenic source.  相似文献   

14.
Spatial and temporal variations of heavy metal contamination in sediments of a small mangrove stand in Hong Kong were examined by laying two transects perpendicular across the shore. Surface sediment samples were taken along the two transects running landward to seaward at intervals of 5 or 10 m during December 1989, and March, July and September 1990. Total concentrations of Cu, Zn, Mn and Pb did not show any specific trend along each transect, although the maximum concentration of heavy metals tended to occur at the landward edge. There was a high level of variability among locations within each transect; for instance, the Cu concentrations fluctuated from 1 to 42 μg g−1. Certain sites contained exceptionally high levels of total metals. Total concentrations of Cu, Zn, Mn and Pb as high as 42, 150, 640 and 650 μg g−1, respectively, were recorded, implying contaminated sediment. A comparison of the two transects indicated that the sediments of Transect B seemed to contain higher total Zn but lower Cu and Mn concentrations than those of Transect A. Most of the heavy metals accumulated in the sediments were not extractable with ammonium acetate and no Cu or Pb was detected in these extracts. The concentrations of extractable Zn and Mn were low, less than 10% of the total metal concentration in the sediment, and appeared to decrease from the landward to seaward samples. For both total and extractable metals, there were significant seasonal fluctuations for both transects, but no specific trends could be identified. These spatial and temporal variations suggest that the scale and representativeness of sampling require careful planning, and a single sample might not give a satisfactory evaluation of the levels of heavy metal contamination in mangrove ecosystems.  相似文献   

15.
Distributions and magnitude of metals in water, sediment and soil collected from the watershed and estuarine areas of southern Bohai Sea, were investigated. The largest dissolved concentrations of As, Cu and Zn in water were 347.70, 2755.00, 2076.00 μg/L, respectively, much higher than corresponding drinking water guidelines. The greatest concentrations of Cu, Zn, Cr, Ni, Pb, As and Cd in sediments were 1462.2, 1602.17, 196.43, 67.15, 63.54, 73.86 and 1.41 mg/kg, dw, respectively. The mean concentrations of Cu, Ni, Cd, Zn, Cr, Pb and As in soils were 24.67, 24.73, 0.14, 64.75, 56.52, 25.12 and 9.34 mg/kg, dw, respectively. Land use was confirmed to be an important factor of influence on soil metal concentrations. Metal contents along the watershed of Jie River were significantly greater than in other locations. The detection of metals in relatively high concentrations from different environmental matrices in this region indicates the necessity of further studies.  相似文献   

16.
Temporal trends in metal concentrations, i.e. Ag, Cd, Cu, Cr, Hg, Ni, Pb and Zn, measured in soft tissues of Mytilus galloprovincialis mussels and Crassostrea gigas oysters collected from estuarine waters within the Basque Country (Bay of Biscay), have been investigated to determine if actions undertaken have improved the environmental quality of rivers and estuaries. Data compiled between 1990 and 2010 have been analysed statistically, applying the Mann–Kendall and the Mann–Whitney–Wilcoxon tests. Moreover, in those cases with significant trends, the Kolmogorov–Zurbenko Adaptive (KZA) filter was applied to detect abrupt changes. Results showed significant decreasing trends for some metals, i.e. Ni, Cu, Pb and Zn, and differences between medians. Trend lines showed abrupt changes occurring between 1998 and 2002. Therefore, observed downward trends were related to increased wastewater treatment and diversions of discharges to ocean, implemented mainly during 2000–2002.  相似文献   

17.
To investigate the influence of mangrove reforestation on heavy metal accumulation and speciation in intertidal sediments, core sediments from a restored mangrove forest and adjacent mud flat in Yifeng Estuary (southeastern China) were analyzed. The chemical speciation of heavy metals (Pb, Zn, Cu, Cr and Ni) was determined according to a sequential extraction procedure. Special attention was paid to the upper 20 cm of sediment, in which metal accumulation was enhanced and speciation was obviously modified. Mangrove reforestation decreased the concentrations of all metals in the acid-soluble fraction and increased metal concentrations in the oxidizable fraction. Increased Pb, Zn and Cu concentrations and decreased Ni and Cr concentrations were observed in the reducible fraction. These results suggest that mangrove reforestation facilitated the accumulation of heavy metals in the upper sediment layers but decreased their bioavailability and mobility.  相似文献   

18.
In the recent years,the Red Sea coast of Yemen has been severely affected by intensive anthropogenic activities.The current study constitutes a thorough inquiry to evaluate the extent of heavy metals pollution in Yemen's Red Sea coast sediment and identifies the possible sources of pollution.The concentrations of five metals(copper(Cu),zinc(Zn),cadmium(Cd),lead(Pb),and nickel(Ni))collected from nine sites along the Red Sea coast of Yemen were assessed using an atomic absorption spectrophotometer(ASS).Sediment quality indices,such as the sediment quality guidelines(SQGs),potential ecological risk(RI),contamination factor(CF),pollution load index(PLI),geoaccumulation index(Igeo),and modified degree of contamination(mCd)were computed.In addition,multivariate statistical techniques(principal component analysis(PCA),hierarchical cluster analysis,and Pearson's correlation analysis)were applied to identify the potential sources of metals.The mean concentrations of Cu,Zn,Cd,Pb,and Ni were 51.3,61.9,4.02,9.9,and 33.4 mg/kg dry wt,respectively.The spatial distribution revealed that the metals concentrations were high at the middle zone and low southward of Hodeida city.According to the SQGs,the adverse biological effects of metals were occasionally associated with Cu and Cd,frequently associated with Ni,and not expected to occur with Zn and Pb.The RI indicated that the sediment of the studied sites pose low(RI<50)to considerable(100≤RI<200)ecological risk.The mean effect range-median quotient(M-ERM-Q)indicated that the combination of the studied metals had the toxicity probability of 21%at all studied sites.Igeo and CF indicated that the metals concentrations were in the descending order of:Zn>Ni>Pb>Cd>Cu,whereas the PLI and mCd indicated that Ras Isa(Site 5)and Urj village(Site 6)were the most polluted sites.PCA,cluster analysis,and correlation analysis found that Cd,Pb,and Ni mostly originated from anthropogenic sources while Cu and Zn were mainly derived from natural sources.Thus,it is evident that the intensive anthropogenic activities had negative influence on metals accumulation in the sediment of the Red Sea coast of Yemen leading to detrimental effects to the whole ecosystem.These comprehensive findings provide valuable information and data for future monitoring studies regarding heavy metals pollution and sediment quality at the Red Sea coast of Yemen.  相似文献   

19.
The particulate concentrations of 17 trace metals, Al, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Se, Ag, Sb, Au, Hg, Pb and Th have been measured in the marine atmosphere (58 samples) and in the deep waters (35 samples) of the Tropical North Atlantic. For oceanic suspended matter, our results are similar to those in samples from the Atlantic and the Pacific Oceans collected during the GEOSECS Program. Based on these results, we have made a flux balance for the mixed layer between input via the atmosphere and removal through small and large particles. These data show that the primary flux of suspended aluminosilicates in the Tropical North Atlantic is attributable to the atmospheric input. Elements Sc, Th, Fe, V, Mn, Co and Cr show high correlation with Al in the marine atmosphere. Of these elements, Fe, Mn, V, Co and Cr are influenced by additional processes such as biological, in the marine environment. For elements Ni, Cu, Zn, Se, Ag, Sb, Au, Hg and Pb, we observe high enrichments (relative to average crustal material) in the marine atmosphere which may be due, at least partially, to the influence of anthropogenic sources. These metals also show similar enrichments in deep ocean suspended matter. Model calculations indicate that the atmospheric flux may not control the deep ocean particulate chemistry of Ni, Cu, Zn, Ag, Sb, Au and Hg. Hence it is likely that, for these elements, the enrichment in the ocean is due to processes within the marine regime, for example their involvement in the biological cycle of the ocean. For Se and Pb, the atmospheric source looks to be the dominant contribution to their particulate concentration in seawater. In the deep North Atlantic, particulate Pb appears to be mostly of anthropogenic origin, which is not the case for Se.  相似文献   

20.
分析了阳宗海柱状及表层沉积物中Al、Fe、Mn、Zn、Cr、Co、Ni、Cu、As、Cd、Pb等金属元素的含量,结合沉积年代学,研究了沉积物重金属污染的时空变化和潜在生态风险特征.结果表明,表层沉积物中重金属含量具有一定的空间差异性,As、Cd、Cu、Pb和Zn在中东部湖区含量较高,而Cr、Co、Ni含量高值位于南、北湖区的近岸区域;柱状沉积物中,1990s之前As、Cd、Cu、Pb和Zn含量较为稳定,1990s中后期以来,其含量逐渐增加,并在2009-2010年前后达到最大值,此后逐渐下降;而柱状沉积物中Cr、Co、Ni含量变化趋势与Al、Fe相似,总体上由下向上逐渐降低,这主要与沉积物质地(粒度)逐渐变粗有关.重金属富集系数表明,阳宗海沉积物中主要污染元素为As、Cd、Cu、Pb和Zn,1990s中后期污染程度快速增加,2009-2010年前后达到峰值,此后污染程度逐渐降低;表层沉积物中Cu为未污染至"弱"污染水平;Zn、Pb为"弱-中等"污染水平,As为"中等-强"污染水平,Cd为"弱-强"污染水平,中东部湖区污染程度高于其他湖区,这可能与该湖区缺少入湖径流、自然碎屑物质沉积速率较低以及砷污染事件等人为源的重金属贡献影响更为显著有关.生态风险评价结果表明,在2002-2010年前后沉积物重金属达到"中等-强"潜在生态危害,主要贡献因子是Cd和As,近年来其生态风险等级逐渐降低;表层沉积物中重金属在中东部湖区具有"中等"程度潜在生态危害,而其他湖区表层沉积物重金属具有较低程度的潜在生态风险.  相似文献   

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