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1.
The quantitative significance of organic matter degradation in bringing about the early diagenetic mobility of anthropogenic trace metals (Cu, Zn, Pb) is assessed specifically in relation to the use of estuarine sediments as historical records of pollution. A 1,500 mm salt-marsh sediment depth profile from Tites Point, Severn Estuary, England, was sampled at 10-mm intervals. Organic carbon determinations were carried out by a wet oxidation technique, and ‘organic fraction’ metals were separated by sequential leaching. Results demonstrated that organic phase metals are quantitatively significant in Severn Estuary sediments, particularly Cu and Zn (Cu>Zn), and that metals are probably released from this fraction during early diagenesis. The degree of release, and the apparent loss of the released trace metals from the sediment, would suggest that the use of estuarine sediments as historical records of pollution requires qualification.  相似文献   

2.
Surficial sediment samples were collected at 47 stations in Little Traverse Bay, Lake Michigan, to determine the geochemical associations between certain rare earth elements (REE's) and trace metals. Each sample was analyzed for carbonate carbon, organic carbon, grain size, and the elements Al, Ca, Ce, Co, Cr, Eu, Fe, Hf, La, and Mn. Two distinct Ce subpopulatins were identified by graphical analysis, and an R-mode factor analysis was applied to data from the “enriched” Ce subpopulation (18 samples). Results show that the REE's and trace metals are primarily enriched in the authigenic phase of these sediments. Partial correlation analyses indicate that the REE's are primarily associated with hydrous Fe oxides relative to organic matter in this phase. The ratio of Ce/La concentrations increased markedly from the bay margins to the central trough of the bay, indicating that Ce, similar to Fe, exhibits a variable oxidation state in the authigenic phase of nearshore fine-grained sediments. The results of the present study suggest that the REE's and trace metals behave coherently in the authigenic phase of recent lacustrine sediments, and the REE's may be useful as geochemical tracers to differentiate between trace metal enrichments in surface sediments as a result of diagenesis and pollution loadings.  相似文献   

3.
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   

4.
Eighteen sediment samples and six water-column samples were collected in a small (6 km2), coastal embayment (Port Jefferson Harbor, New York) to define a high-resolution spatial distribution of metals and to elucidate sources of contaminants to the harbor. Sediment metal (Ag, Cu, Fe, Ni, Pb, V, and Zn) concentrations varied widely, reflecting differences in sediment grain size, with higher metal concentrations located in the fine-grained inner harbor sediments. Calculated enrichment factors for these sediments show that Ag, Pb, Cu, and Zn are elevated relative to both crustal abundances and their respective abundances in sediments in central Long Island Sound. Metal concentrations were 1.2 to 10 fold greater in water from the inner harbor compared to water from Long Island Sound collected outside the mouth of the harbor. Spatial variations in trace metals in surface waters within the bay parallel the spatial variations of trace metals in sediments within the harbor. Elevated water-column metal concentrations appear to be partially derived from a combination of diagenetic remobilization from contaminated sediments (e.g., Ag) and anthropogenic sources (e.g., Cu and Zn) within the southern portions of the harbor. Although the National Status and Trends Program had reported previously that sediment metal concentrations in Port Jefferson Harbor were low, the results of this study show sediment metals have high spatial variability and are enriched in the inner harbor sediments at levels comparable to more urbanized western north shore Long Island harbors.  相似文献   

5.
Chabahar Bay in SE of Iran is a shallow semi-enclosed environment affected by anthropogenic activities. In this paper, 19 sediment samples were collected and concentration of selected metals (Cu, Pb, Zn, Cd, Ni, Cr, Co, V and Fe) was determined using ICP-MS analytical method. Sediment samples from five stations were also selected for sequential extraction analysis and concentration of metals in each fraction was determined using ICP-OES. In order to investigate the environmental quality of Chabahar Bay, geographic information system (GIS) along with geochemical data, environmental indices and statistical analyses were used. Calculated contamination degree (Cd) revealed that most contaminated stations (Ch3, S1 and S3) are located SE of Chabahar Bay and contamination decreases in a NW direction. The S9 station, west of the bay, is also contaminated. High organic matter (OM) content in the sediments is most likely the result of fuel and sewage discharge from fishing vessels along with discharge of fishing leftovers. Significant correlation coefficient among OM, Fe, Cu, Pb, Zn and Cd seemingly reflects the importance of the role that OM and Fe oxy-hydroxides play in the metals mobility. The results of hierarchical cluster analysis (HCA), computed correlation coefficient and sequential extraction analysis suggest that Cu, Pb, Zn and Cd probably come from antifouling and sea vessel paints, while Ni, Cr, Co, V and Fe are most likely contributed by ophiolitic formations located north of the bay and/or deep sea sediments. Average individual contamination factors (ICFs) indicated that the highest health hazard from the bay is posed by Cu, Pb and Zn.  相似文献   

6.

Phosphorus (P) plays an important role in the eutrophication of river and marine environments. The adsorption-desorption processes of P by estuarine sediment were studied to better understand the P behaviour in the Loughor Estuary in Carmarthen Bay, UK. Three types of models were used to estimate the P adsorption isotherm for five sediment samples from the Loughor Estuary. The Langmuir adsorption isotherm showed a good fit with the linear (data) isotherm. The P desorption from bed sediment was measured as the easy exchangeable P (MgCl2 extractable). A negative correlation was found between adsorbed P in bed sediment and median particle size. A positive correlation was also found between P adsorbed and metals such as iron (Fe), aluminium (Al) and calcium (Ca) as well as the total organic carbon (TOC).

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7.
The composition of clay minerals in the subcolloid fraction from the uppermost layer of bottom sediments in the northern part of Amur Bay was determined by X-ray powder diffraction analysis, and the enrichment of 33 elements in the subcolloid and pelite fractions of the surface deposits from a number of sites at the marginal filter of the Razdol’naya River was studied by ICP-MS.Fe, U, and chalcophile elements are contained in the highest concentrations in sediments from all sampling sites within the filter. The bottom sediments are not enriched in trace, alkali, and alkali-earth elements. The maximum concentrations of chemical elements were found in deposits from the brackish part of the marginal filter, perhaps, because of the formation of Fe and Mn (Al) hydroxides. Bottom sediment at the boundary between the brackish and marine parts of the filter contain the lowest concentrations of the examined elements.  相似文献   

8.
《Applied Geochemistry》2002,17(9):1171-1181
Sediment cores were collected from 20 lakes from the Muskoka region of Ontario, Canada, to study vertical changes in trace metal concentrations with depth and the distribution of metals amongst humic material, amorphous and crystalline Fe and Mn oxides, insoluble organics/sulphides, and silicates. Based on their total concentrations, trace elements displayed different degrees of affinity for the organic fraction (represented by organic C) and the mineral fraction (represented by Al). Certain elements (Hg, As, Sb, Pb, Cd, and Zn) displayed a positive correlation with organic C, a negative correlation with Al, and enrichment in surface sediments (with enrichment factors ranging from 2 to 24). Detailed speciation studies revealed that these elements were associated mainly with humic material and to a lesser extent with oxides in surface sediments. Other elements (Al, Cr, Co, Fe, and Mn) displayed a negative correlation with organic C, a positive correlation with Al, and no consistent enrichment in their total concentration at the surface. The speciation study revealed that metals of the latter group were mainly associated with the silicate fraction in both surface and deep sediments. This study shows that relative affinities for organic and mineral fractions play an important role in the distribution of trace metals during burial and diagenesis, and hence in the shape of their vertical profiles.  相似文献   

9.
The distributions of particulate elements (Al, P, Mn, Fe, Co, Cu, Zn, Cd, and Pb), dissolved trace metals (Mn, Fe, Co, Cu, Zn, and Cd), and dissolved nutrients (nitrate, phosphate, and silicic acid) were investigated in the Gulf of the Farallones, a region of high productivity that is driven by the dynamic mixing of the San Francisco Bay plume, upwelled waters, and California coastal surface waters. Particulate metals were separated into >10 and 0.4-10 μm size-fractions and further fractionated into leachable (operationally defined with a 25% acetic acid leach) and refractory particulate concentrations. Dissolved metals (< 0.4 μm pore-size filtrate) were separated into colloidal (0.03-0.4 μm) and soluble (<0.03 μm) fractions. The percent leachable particulate fractions ranged from 2% to 99% of the total particulate concentration for these metals with Mn and Cd being predominantly leachable and Fe and Al being predominantly refractory. The leachable particulate Pb concentration was associated primarily with suspended sediments from San Francisco Bay and was a tracer of the plume in coastal waters. The particulate trace metal data suggest that the leachable fraction was an available source of trace metal micronutrients to the primary productivity in coastal waters. The dissolved trace metals in the San Francisco Bay plume and freshly upwelled surface waters were similar in concentration, with the exception of Cu and Co, which exhibited relatively high concentrations in plume waters and served as tracers of this water mass. The dissolved data and estimates of the plume dynamics suggest that the impact of anthropogenic inputs of nutrients and trace metals in the San Francisco Bay plume contributes substantially to the concentrations found in the Gulf of the Farallones (10-50% of estimated upwelled flux values), but does not greatly disrupt the natural stoichiometric balance of trace metal and nutrient elements within coastal waters given the similarity in concentrations to sources in upwelled water. In all, the data from this study demonstrate that the flux of dissolved nutrients and bioactive trace metals from the San Francisco Bay plume contribute to the high and relatively constant phytoplankton biomass observed in the Gulf of the Farallones.  相似文献   

10.
A sequential extraction method was employed to extract the metals Al, Ag, Cd, Co, Cr, Cu, Pb, Fe, Li, Mn, Ni, and Zn from a 10-m sediment core taken from the Tilbury Basin on the Thames Estuary. Characteristics of the observed metal partitioning distributions were attributed primarily to the composition of the estuarine waters at the time of deposition. For some metals, a decrease in the bulk sediment metal concentrations from a depth of ?6.59 m ODN to the surface was also observed in one of the solid phases. This was the case for Cr, Cu, and Pb extracted from the organic phase and for Zn extracted from the carbonate phase. This decrease in sediment concentrations is thought to reflect reported improvements to water quality in this region of the Thames Estuary in the early 1960s, following updating of major sewage treatment works (STW) approximately 20 km upstream. These findings give an indication of the influence of estuarine inputs from STW on metal partitioning distributions. The order of mobility for the metals of environmental concern was Cd>Ag>Cr>Ni, Zn>Co, Cu, Pb. for Cd and Ag there was a tendency to partition towards the exchangeable phase, both at the surface and at depth, which indicates the potential for long-term leaching of these metals from the sediments.  相似文献   

11.
Geochemical, mineralogical and textural analyses were carried out in core sediments off Adyar estuary, Bay of Bengal, India to record the contamination trend from urban and industrial activities during the historical past. Quartz, feldspar, kaolinite, chlorite and illite were the main lithogenic and clay minerals; carbonate was the predominant biogenic mineral. Trace metals (Fe, Al, Cu, Cr, Ni, Pb and Zn) indicate more enrichment in the surface sediment layers due to recent anthropogenic activities. The mean anthropogenic factor (AF) values for trace metals in core sediments decreased in the following order: Cr > Ni > Zn > Cu > Pb. The pollution load index (PLI) values in Adyar core sediments ranged from 1 to 1.25 with an average of 1.07. Based on AF, PLI, and sediment quality guidelines values for trace metals, significant metal enrichment and ecological risk were obtained in upper-most sediment layer. Multivariate statistical methods such as correlation matrix, principal component analysis and cluster analysis were carried out to find the relationships among the texture size, metals and minerals. The pollution of Adyar estuarine sediments was started in the 1960s, responding to the rapid economic development in Chennai coastal and Adyar estuarine region in the last five decades. Despite these high concentrations in the upper layer, development and expansion of industries are still continuing. The stricter regulations for the discharge and remediation of sediments are urgent for the conservation of environments and human health.  相似文献   

12.
《Applied Geochemistry》2004,19(7):1065-1074
Potentially toxic metals exist in many reservoirs of surface water and therefore require an understanding of their occurrence, distribution, and mobility. The sediment accumulating at the bottom of the Dillon Reservoir, Colorado is contaminated with metals (Cu, Pb, Zn, Cd, Mo, etc.) that are primarily sorbed to Fe and Al hydroxides present in the sediment. The metals are derived from weathering of mineralized bedrock and mine tailings in the surrounding drainage basins. Sediment samples from the Dillon Reservoir were analyzed for major and trace elements and acidification experiments were performed to quantify the fraction of metals released from the sediment as a function of changes in pH. The highest percentages of metals are released from the sediment at low pH with the exception of Mo which has the highest percent released at near neutral pH. In addition, seasonal fluctuations in the concentrations of metals in the water of the Dillon Reservoir can be explained by changes in pH of as low as 0.2 pH units.  相似文献   

13.
Mining/smelting wastes and reservoir sediment cores from the Lot River watershed were studied using mineralogical (XRD, SEM–EDS, EMPA) and geochemical (redox dynamics, selective extractions) approaches to characterize the main carrier phases of trace metals. These two approaches permitted determining the role of post-depositional redistribution processes in sediments and their effects on the fate and mobility of trace metals. The mining/smelting wastes showed heterogeneous mineral compositions with highly variable contents of trace metals. The main trace metal-bearing phases include spinels affected by secondary processes, silicates and sulfates. The results indicate a clear change in the chemical partitioning of trace metals between the reservoir sediments upstream and downstream of the mining/smelting activities, with the downstream sediments showing a 2-fold to 5-fold greater contribution of the oxidizable fraction. This increase was ascribed to stronger post-depositional redistribution of trace metals related to intense early diagenetic processes, including dissolution of trace metal-bearing phases and precipitation of authigenic sulfide phases through organic matter (OM) mineralization. This redistribution is due to high inputs (derived from mining/smelting waste weathering) at the water–sediment interface of (i) dissolved SO4 promoting more efficient OM mineralization, and (ii) highly reactive trace metal-bearing particles. As a result, the main trace metal-bearing phases in the downstream sediments are represented by Zn- and Fe-sulfides, with minor occurrence of detrital zincian spinels, sulfates and Fe-oxyhydroxides. Sequestration of trace metals in sulfides at depth in reservoir sediments does not represent long term sequestration owing to possible resuspension of anoxic sediments by natural (floods) and/or anthropogenic (dredging, dam flush) events that might promote trace metal mobilization through sulfide oxidation. It is estimated that, during a major flood event, about 870 t of Zn, 18 t of Cd, 25 t of Pb and 17 t of Cu could be mobilized from the downstream reservoir sediments along the Lot River by resuspension-induced oxidation of sulfide phases. These amounts are equivalent to 13-fold (Cd), ∼6-fold (Zn), 4-fold (Pb) the mean annual inputs of the respective dissolved trace metals into the Gironde estuary.  相似文献   

14.
Accumulation and distribution of heavy metals and phosphorus in sediments impact water quality. There has been an increasing concern regarding fish health in the St. Lucie Estuary, which is related to increased inputs of nutrients and metals in recent decades. To investigate vertical changes of contaminants (P, Cd, Cr, Co, Cu, Ni, Pb, Zn, and Mn) in sediments of the St. Lucie Estuary in South Florida, 117 layer samples from six of the 210 to 420 cm depth cores were analyzed for their total and water-soluble P and heavy metals, clay, total Fe, Al, K, Ca, Mg, Na, and pH. Principal component analysis (PCA) was used in two sets of analytical data (total and water-soluble contaminant concentrations) to document changes of contaminants in each core of sediments. The PCA of total contaminants and minerals resulted in two factors (principal components). The first and second factors accounted for 61.7 and 17.2 % of the total variation in all variables, and contrast indicators associated with contaminants of P, Cd, Co, Cr, Ni, Pb, Zn, and Mn and accumulation of Fe and Al oxides, respectively. The first factor could be used for overall assessment of P and heavy metal contamination, and was higher in the upper 45–90 cm than the lower depths of each core. The concentrations of P and heavy metals in the surface layers of sediments significantly increased, as compared with those in the sediments deeper than 45–90 cm. The PCA of water-soluble contaminants developed two factors. The second factor (Cu–P) was higher in the upper than the lower depths of the sediment, whereas the highest score of the first factor (Cd–Co–Cr–Ni–Pb–Zn–Mn) occurred below 100 cm. The water-soluble Cu and P concentrations were mainly dependent on their total concentrations in the sediments, whereas the water-soluble Cd, Co, Cr, Ni, Pb, Zn, and Mn concentrations were mainly controlled by pH.  相似文献   

15.
Heavy metals were investigated in the sediments of the Ventspils Harbour located in north-west Latvia (eastern Baltic Sea). Sediment samples were analysed for major and trace metals by ICP-AES, supplemented by inorganic and organic carbon as well as grain-size distributions. Principal component analysis of the data resulted in two main parameter clusters associated with Ca- and Al-rich material and indicated differing behaviour of Pb, Cu, Zn, N and P. Normalization with respect to Ca and Al by least absolute values regression removed the spatial pattern of sediment metal content in the harbour. High residual concentrations at individual sites were associated with local contaminations, whereas the overall concentration pattern was governed by the transport of riverine fine material. Dilution with coarser, quartz-rich marine sediments led to a pronounced heavy metal concentration drop towards the harbour gates. High mixing was an important feature of sediment dynamics in the Ventspils Harbour, hampering contaminant source identification and sediment monitoring.  相似文献   

16.
《Applied Geochemistry》2002,17(8):1081-1092
Different types of fine-grained chemical precipitates were characterized in the surroundings of the pyrite-chalcopyrite mine of Libiola (Northern Italy). Both water chemistry and sediment composition were used to investigate metal mobility near the mine area. Local drainage waters were very acidic (with a pH as low as 2.5) and were rich in dissolved metals (Fe, Al, Cu, Zn, Mn, Ni). Sediments associated with low pH water (pH <4.5) were ochreous mixtures of schwertmannite and goethite with traces of jarosite. Their chemistry was dominated by Fe and they had, compared to other sediments investigated, low concentrations of other metals. When the acidity decreased gradually, other precipitates formed. At a pH of approximately 5, a poorly crystalline, whitish, Al-rich precipitate occurred. At a pH between 6 and 7, a poorly crystalline, blue, Cu (Zn) rich phase was present. These “sequential” precipitation events progressively reduced the metal loading typical of the acidic mine water when there was a gradual mixing with normal water. When a sudden mixing between normal waters (pH ∼8, Ca–HCO3, low metal bearing) and acidic waters took place, a rapid flocculation occurred of mixed precipitates containing Fe, Al and trace elements.  相似文献   

17.
 Sediment origin and transport were determined in a shallow 447 km2 coastal lagoon in Brazil, using the distribution of major elements in bottom and suspended sediments. Applying multivariate analysis, the sum of normalized concentrations of Ti, Fe, and Al in sediments was selected to trace the terrigenous influence in bottom sediments, whereas Ca, Si, and K were used as indicators of marine influence. Sepetiba Bay bottom sediments are dominated by up to 80% terrigenous inputs. The open bay sediments are enriched in P, Mg, K, and Ca because of the intensive water column primary production. The inner bay forms an independent circulation cell with a predominance of terrigenous sediments. The results suggest a long residence time for particles in the bay, demonstrated by the magnitude of resuspension flux compared to the total sediment input to the bay. Received: 29 May 1996 · Accepted: 17 December 1996  相似文献   

18.
Heavy metals distribution in core sediments, different size fractions of bed sediments (>212 urn, 90-212 jam, 63–90 urn, 53–63 urn, < 53 urn), and suspended sediments (>30 urn, 20–30 m, 10–20 urn, 2–10 urn, <2 m) have been discussed. Pb, Zn, and Cr have been accumulating in recent years in the sediments. Si, Al, Fe, Ca, and Mg dominate the bed and suspended sediment composition. Metals show increasing concentrations in finer sediments. Applying multivariate analysis to sediment composition, metals have been grouped into different factors depending upon their source of origin. Chemical fractionation studies on suspended and bed sediments show Fe, Zn, Cu, and Pb are associated with the residual fraction and Mn with the exchangeable fraction.  相似文献   

19.
Many small estuaries are influenced by flow restrictions resulting from transportation rights-of-way and other causes. The biogeochemical functioning and history of such systems can be evaluated through study of their sediments. Ten long and six short cores were collected from the length of Jordan Cove, Connecticut, a Long Island Sound subestuary, and analyzed for stratigraphy, radionuclides (14C, 210Pb, 226Ra, 137Cs, and 60Co), and metals (Ag, Cd, Cu, Pb, Zn, Fe, and Al). For at least 3,800 yr, rising sea level has gradually inundated Jordan Cove, filling it with mud similar to that currently being deposited there. Long-term sediment accumulation in the cove averaged close to 0.1 cm yr−1 over the last three millennia. Recent sediment accumulation rates decrease inland from 0.84 cm yr−1 to 0.40 cm yr−1, and are slightly faster than relative sea-level rise at this site (0.3 cm yr−1). Similarity of depth distributions of trace metals was used to confirm relative sediment accumulation rates. 60Co and Ag are derived from sources outside the cove and its watershed, presumably the Millstone nuclear power plant and regional contaminated sediments, respectively. The combined data suggest that Long Island Sound is an important source of sediment to the cove; a minor part of total sediment is supplied from the local watershed. Trace metal levels are strongly correlated with Fe but not with either organic matter or Al. Sediment quality has declined in the cove over the past 60 yr, but only slightly. Cu, Pb, and Zn data correlate strongly with Fe but not with either organic matter or aluminum. Ratios of Ag to Fe and to trace metals suggest that Ag in the cove is derived almost entirely from Long Island Sound. This result supports the notion that Fenormalized Ag can serve as a better tracer of some kinds of contamination than more common and abundant metals, like Cu, Pb, and Zn. *** DIRECT SUPPORT *** A01BY085 00008  相似文献   

20.
Florida Bay is a shallow carbonate estuary in South Florida. It receives fresh waters from the Everglades that contribute a number of metals to the Bay. The Bay is the largest estuary in Florida with nearly pristine conditions. In this paper we report the first extensive studies of trace metals in the Bay. The seasonal distributions of trace metals (Sc, V, Cr, Co, Cu, Fe, Pb, Mn, Ni and Al) were determined on surface waters in Florida Bay and adjacent waters. The measurements in the Bay were made from May 2000 to May 2001, and the adjacent waters were sampled in September 2000 and May 2002. Most of the dissolved trace metals exhibited their maximum concentrations in summer, except Al and Pb that did not show any seasonal variability. The seasonal variations of the metals are related to the influx of fresh water from rainfall. The lowest concentrations are found during the dry season in the winter and the highest during the wet season in the summer. Several metals (V, Mn, Al, Sc, Fe, Co, Ni and Cr) exhibited their highest concentrations in the western zone of the Bay. These waters from agricultural areas are influenced by Gulf of Mexico waters, which carry metals coming from Barron, Broad and Shark rivers into the Bay. The Shark River always exhibited high concentrations of V, Mn, Al, Sc, Co and Cr. Other possible influences in the western and north-central zone of the Bay are from Flamingo Center, the creeks of Taylor Slough and the mangrove fringe of the Everglades. High concentrations of Al, Co, Ni, Cr, Cu, Fe, and Pb were detected in the eastern zone. The high values found in the northeast are influenced by Taylor Slough runoff and in the southeast by Key Largo, Tavernier Marina and the drainage from the main highway (US1) on Tavernier Key. The minimum concentrations for most of the metals were found in areas near the Key channels that exchange waters between Florida Bay and the Atlantic Ocean (Gulf Stream). The adjacent waters in the Atlantic side including the Gulf Stream waters showed very low concentrations for all the metals studied except for V. In the Bay correlations of V were found: (1) V with salinity and Al and (2) Sc with Si. Most of the other metals did not show any strong correlations with nutrients or salinity. Florida Bay is thus not a typical estuary due to the unique structure of its mud banks and multiple inputs of metals from the mangrove fringe in the north.  相似文献   

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