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1.
This paper investigates the natural and anthropogenic processes controlling sediment chemistry in Admiralty Bay, King George Island, Antarctica, emphasizing the area affected by the Brazilian Antarctic Station Comandante Ferraz (Ferraz). Total and bioavailable concentrations of sixteen elements were determined in 32 sediment and 14 soils samples. Factor analysis allowed us to distinguish three groups of samples: (1) Ferraz sediments, with higher content of total trace metals and organic matter; (2) control sediments, with intermediate characteristics; (3) Ferraz soils, with higher bioavailability of most metals due to its oxidizing condition and low organic matter content. Major elements such as Fe, Al, Ca and Ti presented similar levels in all three groups. Enrichment factor calculations showed that paints, sewage and petroleum contamination enhanced metal concentrations in Ferraz surface sediments as follows: B, Mo, and Pb (>90%); V and Zn (70-80%); Ni, Cu, Mg, and Mn (30-40%). Despite evidence of contamination in these sediments, the low bioavailability, probably caused by iron-sulfide, indicates small environmental risks.  相似文献   

2.
《Marine pollution bulletin》2014,78(1-2):341-348
Sources and transport processes of As, Cu, Cd and Pb were studied in different environmental compartments of Deception Island, an active volcano in the South Shetland Islands, Antarctica. Element concentrations in fresh water samples are consistent with the lowest values reported elsewhere in Antarctica. Interestingly, higher concentration values of As were found in samples collected in or near spring water courses and its transport may be related with processes of lixiviation in underground waters. While in saline waters Cu and Pb had important punctual sources, concentration values for Cd were consistently high pointing to the existence of a natural and diffuse source possibly related with the hydrothermal activity. The high Si/Al ratio, low carbon content, and a non-significant anthropogenic heavy metal input may explain the surprisingly homogeneous heavy metal content found in sediment samples.  相似文献   

3.
Surface sediment samples collected from the inner shelf region of the Bay of Bengal, were analysed for the major elements and total and acetic acid available trace elements (Al, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Si, Zn) to evaluate geochemical processes influencing their distribution. Major elemental analysis showed that the sediments had high concentrations of Si and relatively low concentrations of Al and Fe. Both major elemental and trace metal concentrations indicated that the sediments represent weathered products of granite and charnockite. Normalization of metals to Al indicated relatively high enrichment factors for Pb, Cd, Zn and Cr. The higher proportions of nondetrital Pb (66%), Cd (41%) and Co (28%) reveal metal contamination due to anthropogenic inputs. Factor analysis (FA) identified six possible types of sedimentological and geochemical associations. The dominant factor accounting for 26.9% of the total variance identifies an anthropogenic input and accumulation of nondetrital Cd, Co, Cr, Ni and Pb. Association of these metals with CaCO3 reveals that shell fragments in the surface sediments are likely act as a carrier phase for nondetrital metals. The results are discussed in the context of the sources and pathways of elements in the Bay of Bengal.  相似文献   

4.
《国际泥沙研究》2016,(3):226-236
The Murucupi River belongs to the hydrographic network of the Pará River estuary, at the southern portion of the Amazon River mouth, which consists of a fluvial-marine transitional zone under strong impact of both tidal and fluvial currents. The geochemical results obtained for bottom sediments from the Murucupi River, the Arrozal Channel, and the Pará River indicate a natural variation of Pb, Cr, Cu, Zn, and Ni content among these water ways with no significant anthropogenic influence. According to the threshold effects level (TEL), the contents of trace metals do not offer risk to the local biota. By contrast, the differences in the Pb isotopic composition of sediments in the Murucupi River, the Arrozal Channel, and the Pará River are significant. These isotopic signatures indicate an anthropogenic contribution of Pb in the Murucupi River originating from the domestic effluents of urban centers; industrial waste represented by red mud is not included. These results demonstrate that the Pb isotopic signature is a prospective indicator for future contamination of bottom sediments by trace metals and is useful for identifying contaminants among the possible anthropogenic sources.  相似文献   

5.
The trace metal distribution in the sediments of Laucala Bay, a coastal lagoon with a barrier reef and significant freshwater input, adjacent to Suva, the capital of Fiji (150,000 people), was studied from the point of view of assessing the significance of anthropogenic sources relative to natural ones. Surface sediments from 25 sites in the Bay were analysed for particle size distribution, organic carbon and major (Si, Al, Fe, Ca, Mg) and trace metal (Mn, Zn, Cu, Pb, Cd, Hg) contents. Suspended sediments from one site and shellfish samples from five sites were also analysed. The sediments were found to be mostly of terrigenous origin. Particle size distribution, organic carbon and major elemental composition of the sediments were generally related to location within the Bay. A significant natural source of trace metals in the sediments is the suspended solids transported into the Bay by rivers. The spatial distribution of trace metals could not be fully explained by the particle size distribution and mineral composition of the sediments. Contributions from anthropogenic sources were also suspected, but the degree of enrichment from such sources is not great at the present time.  相似文献   

6.
Victoria Harbour has received substantial loadings of pollutants from industrial and municipal wastewater discharged since the 1950s. Inputs of contaminants have declined dramatically during the last two decades as a result of better controls at the source and improved wastewater treatment facilities. To assess the spatial and temporal changes of metal contaminants in sediments in Victoria Harbour, core and grab sediments were collected. The central harbour areas were generally contaminated with heavy metals. The spatial distribution of trace metals can probably be attributed to the proximity of major urban and industrial discharge points, and to the effect of tidal flushing in the harbour. In the sediment cores, the highest concentrations of trace metals were observed to have accumulated during the 1950s-1980s, corresponding with the period of rapid urban and industrial development in Hong Kong. From the late 1980s, there has been a major decline in the concentrations of trace metals, due to a reduction in industrial activities and to the enactment of wastewater pollution controls in the territory. The Pb isotopic compositions of the sediments revealed the anthropogenic inputs of Pb to the harbour. The (206)Pb/(207)Pb ratios varied from 1.154 to 1.190, which were lower than those of background geological materials in Hong Kong ((206)Pb/(207)Pb: 1.201-1.279). The data also indicated that the Pb in the harbour sediments most likely originated from mixed sources, including the leaded gasoline used in the past and other anthropogenic sources.  相似文献   

7.
Concentrations of major and trace metals were determined in eight sediment cores collected from the inter-tidal zone of the Medway Estuary, Kent, UK. Metal associations and potential sources have been investigated using principal component analysis. These data provide the first detailed geochemical survey of recent sediments in the Medway Estuary. Metal concentrations in surface sediments lie in the mid to lower range for UK estuarine sediments indicating that the Medway receives low but appreciable contaminant inputs. Vertical metal distributions reveal variable redox zonation across the estuary and historically elevated anthropogenic inputs. Peak concentrations of Cu, Pb and Zn can be traced laterally across the estuary and their positions indicate periods of past erosion and/or non-deposition. However, low rates of sediment accumulation do not allow these sub surface maxima to be used as accurate geochemical marker horizons. The salt marshes and inter-tidal mud flats in the Medway Estuary are experiencing erosion, however the erosion of historically contaminated sediments is unlikely to re-release significant amounts of heavy metals to the estuarine system.  相似文献   

8.
《Marine pollution bulletin》2009,58(6-12):816-825
Victoria Harbour has received substantial loadings of pollutants from industrial and municipal wastewater discharged since the 1950s. Inputs of contaminants have declined dramatically during the last two decades as a result of better controls at the source and improved wastewater treatment facilities. To assess the spatial and temporal changes of metal contaminants in sediments in Victoria Harbour, core and grab sediments were collected. The central harbour areas were generally contaminated with heavy metals. The spatial distribution of trace metals can probably be attributed to the proximity of major urban and industrial discharge points, and to the effect of tidal flushing in the harbour. In the sediment cores, the highest concentrations of trace metals were observed to have accumulated during the 1950s–1980s, corresponding with the period of rapid urban and industrial development in Hong Kong. From the late 1980s, there has been a major decline in the concentrations of trace metals, due to a reduction in industrial activities and to the enactment of wastewater pollution controls in the territory. The Pb isotopic compositions of the sediments revealed the anthropogenic inputs of Pb to the harbour. The 206Pb/207Pb ratios varied from 1.154 to 1.190, which were lower than those of background geological materials in Hong Kong (206Pb/207Pb: 1.201–1.279). The data also indicated that the Pb in the harbour sediments most likely originated from mixed sources, including the leaded gasoline used in the past and other anthropogenic sources.  相似文献   

9.
The concentration and areal distribution of selected trace metals (Cu, Zn, Pb, Cd, Mo, Ni, Mn and Hg) in surficial sediments of Saint John Harbour, New Brunswick, Canada, were studied to determine the extent of anthropogenic input and to estimate the effects of dumping dredged material in the outer harbour. Hg and Cd are of especial concern, since the disposal of dredge material containing these two elements is regulated under the Ocean Dumping Control Act.The concentrations of all metals are low: Cu 16, Zn 53, Pb 24, Cd 0.16, Mo 3, Ni 16, Mn 296 and Hg 0.04 μg g?1. Hg and Cd levels in sediments are well below the permissible limits of 0.75 and 0.6 μg g?1, respectively, set by the Ocean Dumping Control Act.The mean concentrations of trace elements are similar to the low mean values in the unpolluted Bay of Fundy. There is an overall decline in concentrations of metals in the sediments from the inner to the outer harbour. Comparison of the metal levels in the sediments from different areas within the harbour indicate that there is a detectable anthropogenic input in the Courtenay Bay area. Trace metal levels at the dumpsite are significantly lower than in the Courtenay Bay area, where the bulk of the dredged material originates.  相似文献   

10.
Deception Island is the most active volcano of the South Shetland Islands-Antarctic Peninsula group, experiencing eruptions in 1967, 1969 and 1970. Local attenuation derived from coda analysis and source parameters derived from Brune's model, for well located seismic events, have been studied in order to complement the available geophysical information. Results show abnormally lowQ 0 values and an abnormally high frequency dependence, as well as large dispersion. These factors are strongly dependent on the path travelled by the seismic wave. Retrieved values of the source parameters (stress drop, seismic moment and source radius), are again abnormally low compared to world-wide average values, for example, those obtained for the Oroville, California aftershock series between June and September, 1976. These results are consistent with some aspects of the geology of Deception Island, such as the very high degree of fracturing and faulting, and the existence of a strong hydrothermal alteration affecting most of the subaerial volcanic rocks. Moreover, the pattern defined for the lateral variations ofQ 0 shows minimum values in the inner bay of the island, close to the most recent eruption vents. A large reduction in spectral amplitudes over a particular frequency range occurs in several observations, corresponding to the path crossing the zone of highest attenuation. This observation suggests the existence of a hot magmatic intrusion produced during the most recent eruption, and coincides with the superficial low density mass distribution obtained from the gravimetric model and the long wave magnetic field component obtained from magnetic surveys. The width of this intrusion is estimated to be about 200 m, in agreement with the previous results obtained analyzing residuals of the location of seismic events.  相似文献   

11.
Measurements of nutrients, dissolved oxygen and trace metals in bottom waters, taken just before the fall turnover, have been evaluated as indicators of eutrophication in inlets. Samples for these analyses were collected in 34 inlets in eastern Canada. The dominant factor (31% of the variance of the dataset) from a principal component analysis of the resulting data was clearly related to eutrophication. This factor included phosphate, ammonia, silicate, dissolved oxygen, iron and manganese, but not cadmium and zinc. It was used to rank inlets according to eutrophication. Comparisons of these rankings with measures of inlet shape revealed that several measures of the significance of sills were good predictors of the eutrophication status. Tidal prism flushing times, and other geometric measures, were poor predictors of eutrophication. Measures of anthropogenic inputs to the inlets were also poor predictors of the eutrophication status: apparently natural processes dominate anthropogenic inputs in these inlets.  相似文献   

12.
A suite of dissolved trace metals (Ag, Cd, Cu and Pb), inorganic nutrients (NO(3), PO(4)), and chlorophyll a was measured along a 55 mile transect from the East River into western and central Long Island Sound. The main objectives of this study were to determine the relative levels of contamination from sewage, and to assess its possible biological impact on local waters. The East River-Long Island Sound system receives large volumes of treated sewage and industrial effluent as a result of the heavy urbanization of the area. Despite these strong environmental pressures, this study is among the first to report dissolved metal levels from that region. Consistent with the locations of anthropogenic sources, a strong east-west concentration gradient was observed for Ag, Pb, NO(3) and PO(4) with the highest levels found in the East River. In contrast, dissolved Cd and Cu were relatively constant throughout the area of study, suggesting that sewage sources have a more limited influence on the levels of those metals. Remobilization from contaminated sediments may represent the primary source of Cd and Cu to the Long Island Sound under low-runoff conditions in summer. Chlorophyll a concentrations, used as an indicator of total biomass, were also low in the East River. These low chlorophyll concentrations could not be explained by nutrient or light limitation, water column stratification, or to advection of phytoplankton out of the river during tidal flushing. These preliminary results suggest a potential toxic effect of sewage on the biological communities of the East River.  相似文献   

13.
A survey on the metal concentrations (As, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, V, Zn) in beach water and sediments is reported from the tourist destination of Acapulco city on the Pacific coast of Mexico. The concentration of dissolved trace metals (DTMs) in beach water and acid leachable trace metals (ALTMs) in sediments indicated that they are anthropogenic in nature due to the increased tourist activities in the crowded beach locations. The statistical analysis indicates Fe and Mn play a major role as metal scavengers in both the medium (water and sediment) and the higher value of other metals is site specific in the study area, indicating that they are transported from the local area. Comparison results suggest that the beach water quality has deteriorated more than the sediments and special care needs to be taken to restore the beach quality.  相似文献   

14.
Marine sediments are the ultimate recipient of nearly all trace metals introduced by man into aquatic ecosystems. This study examined the amounts and distribution of six trace metals (Cd, Cr, Cu, Ni, Pb, Zn) in sediments of Raritan Bay, apolluted estuary. The highest levels of these metals found in Raritan Bay were: Cd-15, Cr-260, Cu-1230, Ni-50, Pb-985, Zn-815. Three metals regimes within Raritan Bay are readily apparent. An area of high values extends across the Bay from the mouth of the Raritan Riverand Arthur Killinto Sandy Hook Bay. This is bounded on the south and northeast by areas of somewhat lower concentrations. An area of relatively low concentrations, near background values, occupies the region at the mouth of the Bay between Sandy Hook peninsula and Coney Island, New York. Metals values from Raritan Bay are compared with other areas and with a few exceptions, the Raritan Bay maximum levels were similar in magnitude to those of areas in Corpus Christi Harbour (U.S.A), Severn Estuary (U.K.), Deep Sea and Florida Lakes, River Blyth (U.K.), dump sites off New York City, various basins off South California, and in Long Island Sound.  相似文献   

15.
Surface sediments collected from the Pearl River Estuary (PRE) and the Daya Bay (DYB) were analyzed for total metal concentrations and chemical phase partitioning. The total concentrations of Cr, Cu, Ni, Pb, and Zn in the PRE were obviously higher than those in DYB. The maximum concentrations of trace metals in DYB occurred in the four sub-basins, especially in Dapeng Cove, while the concentrations of these metals in the western side of the PRE were higher than those in the east side. Such distribution pattern was primarily due to the different hydraulic conditions and inputs of anthropogenic trace metals. The chemical partitioning of metals analyzed by the BCR sequential extraction method showed that Cr, Ni, and Zn of both areas were present dominantly in the residual fraction, while Pb was found mostly in the non-residual fractions. The partitioning of Cu showed a significant difference between the two areas.  相似文献   

16.
太湖表层沉积物重金属元素的来源分析   总被引：42，自引：4，他引：38  
根据太湖MS岩芯重金属元素与Al的线性回归分析及元素/Al、V/Al比率散点图变化规律,讨论了太湖沉积物中重金属元素的来源特征。结果表明:20世纪20年代中期以前,重金属元素主要为自然来源;20年代中期—70年代中期,尽管沉积物中Al、Fe、Zn、Mn、V、Cr等重金属元素含量随沉积物粒度变粗而明显下降,但除Hg受到一定程度的人为污染之外,其它重金属元素仍以自然来源为主,物源有所变化;70年代末期以来,沉积物中重金属元素人为污染逐渐加重,Pb、Cu、Zn、Hg、As等元素既有流域母质来源,又受到一定程度的人为污染。  相似文献   

17.
Deception Island is a volcanic island with a flooded caldera that has a complex geological setting in Bransfield Strait, Antarctica. We use P-wave arrivals recorded on land and seafloor seismometers from airgun shots within the caldera and around the island to invert for the P-wave velocity structure along two orthogonal profiles. The results show that there is a sharp increase in velocity to the north of the caldera which coincides with a regional normal fault that defines the northwestern boundary of the Bransfield Strait backarc basin. There is a low-velocity region beneath the caldera extending from the seafloor to > 4 km depth with a maximum negative anomaly of 1 km/s. Refracted arrivals are consistent with a 1.2-km-thick layer of low-velocity sediments and pyroclastites infilling the caldera. Synthetic inversions show that this layer accounts for only a small portion of the velocity anomaly, implying that there is a significant region of low velocities at greater depths. Further synthetic inversions and melt fraction calculations are consistent with, but do not require, the presence of an extensive magma chamber beneath the caldera that extends downwards from ≤ 2 km depth.  相似文献   

18.
Sediments are very important as trace metal ‘sinks’ in coastal areas. In this paper we present data on the concentrations and calculated fluxes of the trace metals, Fe, Mn, Cu, Pb, Zn, Cd and Ag at nearshore sites in Long Island Sound. In both areas a percentage of the metal accumulation can be ascribed to local human activities with the highest anthropogenic metal fluxes occurring closest to their source.  相似文献   

19.
Levels of Cr, Cu, Fe, Pb, Ni, and Zn in surface sediment from the Voisey's Bay area of coastal Labrador showed no evidence of recent anthropogenic input of metals. Metal concentrations in surface sediments, normalized to Li, fell within the 95% confidence limits of the background levels. Further analysis showed that the Li-metal regression lines from the surface sediments and sediments from 30-cm depth had the same slope and intercepts, suggesting that there was no difference in the metal content of the sediments at the two depths. Li-metal relationships can be used as a measure of the natural variability of the metal concentrations for the region and will serve as a baseline against which future anthropogenic affects may be assessed.  相似文献   

20.
It is important to determine trace metal concentrations in marine sediments because these could be important sources of contamination of marine organisms that reside there. In this study we measured the concentrations of thirteen metals in sediments obtained from Long Island Sound. We found great variations in metal levels for various geographic areas in the Sound; but, generally the highest concentrations found were in the extreme western end of the Sound. Comparison is made between metal levels in sediments from the Sound to seven other areas located in the U.S. and U.K.  相似文献   

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