Interelement relationships and age-related variation of trace element concentrations in liver of striped dolphins (Stenella coeruleoalba) from Japanese coastal waters

Concentrations of 19 trace elements (V, Cr, Mn, Fe, Co, Cu, Zn, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Tl, Hg, and Pb) were determined in the liver of the striped dolphins (Stenella coeruleoalba) collected around Japan during 1977-1982 to examine the sex difference, age dependence, and interrelationships among trace elements. Tissue distribution of trace elements was also investigated in one adult and one fetus specimens. Generally, concentrations of Se, Sr, Ag, Cd, Cs, Ba, Hg, and Pb were higher in the tissues of adult than those of fetus, whereas the opposite trend was observed for Cr and Tl. There were no significant sex differences in the trace element levels in the liver. Significant positive correlations between age (0-26.5 years) and hepatic concentrations were found for Ag, Se, Hg, V, Fe, Pb, and Sr, suggesting their age-dependent accumulation in the liver. In contrast, hepatic concentrations of Mn and Zn decreased with age. Significant positive relationships were observed between Se, and Hg, Ag, V, Fe, and Sr in the liver.     

Interelement relationships and age-related variation of trace element concentrations in liver of striped dolphins (Stenella coeruleoalba) from Japanese coastal waters

Concentrations of 19 trace elements (V, Cr, Mn, Fe, Co, Cu, Zn, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Tl, Hg, and Pb) were determined in the liver of the striped dolphins (Stenella coeruleoalba) collected around Japan during 1977–1982 to examine the sex difference, age dependence, and interrelationships among trace elements. Tissue distribution of trace elements was also investigated in one adult and one fetus specimens. Generally, concentrations of Se, Sr, Ag, Cd, Cs, Ba, Hg, and Pb were higher in the tissues of adult than those of fetus, whereas the opposite trend was observed for Cr and Tl. There were no significant sex differences in the trace element levels in the liver. Significant positive correlations between age (0–26.5 years) and hepatic concentrations were found for Ag, Se, Hg, V, Fe, Pb, and Sr, suggesting their age-dependent accumulation in the liver. In contrast, hepatic concentrations of Mn and Zn decreased with age. Significant positive relationships were observed between Se, and Hg, Ag, V, Fe, and Sr in the liver.     

Interelement relationships and age-related variation of trace element concentrations in liver of striped dolphins (Stenella coeruleoalba) from Japanese coastal waters

Concentrations of 19 trace elements (V, Cr, Mn, Fe, Co, Cu, Zn, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Tl, Hg, and Pb) were determined in the liver of the striped dolphins (Stenella coeruleoalba) collected around Japan during 1977–1982 to examine the sex difference, age dependence, and interrelationships among trace elements. Tissue distribution of trace elements was also investigated in one adult and one fetus specimens. Generally, concentrations of Se, Sr, Ag, Cd, Cs, Ba, Hg, and Pb were higher in the tissues of adult than those of fetus, whereas the opposite trend was observed for Cr and Tl. There were no significant sex differences in the trace element levels in the liver. Significant positive correlations between age (0–26.5 years) and hepatic concentrations were found for Ag, Se, Hg, V, Fe, Pb, and Sr, suggesting their age-dependent accumulation in the liver. In contrast, hepatic concentrations of Mn and Zn decreased with age. Significant positive relationships were observed between Se, and Hg, Ag, V, Fe, and Sr in the liver.     

Dynamics of dissolved major (Na,K, Ca,Mg, and Si) and trace (Al,Fe, Mn,Zn, Cu,and Cr) elements along the lower Orinoco River

This study addresses the changes in dissolved major and trace element concentrations along the Orinoco River, including the mixing zone between the Orinoco and Apure Rivers. Water samples from the Apure and Orinoco Rivers were collected monthly in four sectors over a period of 15 months. Auxiliary parameters (pH, dissolved oxygen, conductivity, and temperature), total suspended sediments, dissolved organic carbon (DOC), and major (Na, K, Ca, Mg, and Si) and trace (Al, Fe, Mn, Zn, Cu, and Cr) element concentrations were measured in all sectors. The relative contribution of both rivers after the Apure–Orinoco confluence was determined using Ca as a tracer. Moreover, a mixing model was developed to determine whether dissolved species exhibit a conservative behavior during mixing. The results indicate that DOC is removed from waters during the Apure–Orinoco mixing, probably due to absorption of DOC on mineral phases supplied by the Apure River. Dissolved Na, Ca, and Mg behave conservatively during the mixing processes, and their concentrations are controlled by a dilution process. The anomaly in the temporal pattern of K in the Orinoco is caused by the input of biogenic K originating from the Apure River during the high‐water stage. The loss of dissolved Si during the low‐water stage can be explained by the uptake of Si by diatoms. Dissolved Mn, Zn, Al, and Fe showed a non‐conservative behavior during the Apure–Orinoco mixing. The removal of Mn and Zn from the dissolved phase can be explained by the formation of Mn‐oxyhydroxides and the scavenging of Zn onto Mn oxides. Dissolved Fe is controlled by redox processes, although the removals of Fe and Al due to the preferential adsorption of large organometallic complexes by mineral surfaces after the Apure–Orinoco confluence can affect the mobility of both elements during transport. The conservative behavior shown by Cu and Cr can be related to the tendency of both elements to be complexed with small organic colloids, which are not preferentially adsorbed by clays.     

Temporal variability of selected dissolved elements in the lower Orinoco River,Venezuela

Monthly analyses of pH, conductance, alkalinity, total suspended solids, dissolved major cations (Na, K, Ca and Mg), and selected dissolved trace elements (Fe, Al, Mn, Cu, Zn and Cr) were conducted on waters of the lower Orinoco River from February 2004 to May 2006. The data show strong seasonal variability. Major cations had maximum concentrations at low water, and were correlated with pH, conductance and alkalinity because of the tributaries coming from the Andean zones, where the weathering of evaporites and carbonate shales controls water chemistry. K concentrations did not show any relation with evaporite weathering, probably because large amounts of K come from the Guayana Shield rivers as a consequence of feldspar weathering. The concentrations of dissolved Fe, Mn and Cu were highest during the high water stage. Concentrations of the elements K, Cr, Zn and Cu are correlated with each other but not with dissolved Fe and Al, which probably are complexed with humic and fulvic substances. Mn concentrations did not show relationships with other variables. Inter‐annual variability of dissolved elements is explained by temporal changes in precipitation. Copyright © 2008 John Wiley & Sons, Ltd.     

Dissolved and particulate trace metal fluxes through the central English Channel, and the influence of coastal gyres

Measurements of dissolved Cd, Co, Cu, Mn, Ni, Pb, and Zn have been made on a seasonal basis at five stations on a north–south transect across the central English Channel between Cherbourg and the Isle of Wight. Vertical and horizontal distributions of dissolved Cd, Pb, Cu and Zn are relatively uniform except for sampling sites near the English coast. Dissolved Mn and Co show increased concentrations in the English coastal waters, and for Mn the seasonal trend in concentration follows the pattern seen in the Strait of Dover with higher values in the late summer. Ni and Cu are higher in concentration on the English side, which reflects mainly riverine sources. Measurements were also made of particulate forms of the metals above plus particulate Al, Ca, Fe, Mg, Sr and Ti. Water column concentrations of particulate metals broadly follow the distribution of suspended particulate matter, with highest concentrations near the UK coast. Trace metal concentrations have been integrated with modelled data on fluxes of water to provide estimates of fluxes for these elements into the eastern Channel, and an initial comparison is made with data for fluxes of metals through the Strait of Dover obtained during an earlier study. A major influence on the fluxes of particulate metals through the Isle of Wight-Cherbourg transect is the gyre system to the South east to the Isle of Wight, which has important east to west as well as west to east transport components. For those elements where the dissolved form of the metal dominates, the large flow of water in the central Channel waters leads to major fluxes of the metals towards the east and the Strait of Dover. However, the high suspended particulate matter loadings in the coastal waters and impact of the gyre system lead to net east to west fluxes of particulate Al, Fe, Mn and Ti. Comparison of these fluxes with data on the net west to east transport of these materials through the Strait of Dover infers that there must be a significant supply of these particulate metals to the eastern Channel.     

Distribution,fractionation, and contamination assessment of heavy metals in offshore surface sediments from western Xiamen Bay,China

Surface sediment samples were collected at 21 offshore sites in western Xiamen Bay, Southeast China.Total concentrations of Li, V, Cr, Co, Ni, Cu, Zn, Sr, Mn,Pb, Ba, Fe, and Ti were determined by inductively coupled plasma-optical emission spectrometry; Hg was determined by atomic fluorescence spectrometry. A modified BCR sequential extraction procedure was used to extract fractions of the above elements. Concentrations of Pb, Cr, and Hg at most sites met the primary standard criteria of Marine Sediment Quality except site S12 for Pb and S7 for Cr, while concentrations of Zn at 17 sites and Cu at seven sites exceeded the criteria. The mean concentration of Hg was three times higher than the background, with a possible source being the Jiulong River. Fe, Ti, Ba, Co, V, and Li dominated the residual phase, mainly from terrestrial input.Ni, Cr, Pb, and Hg in the non-residual phase varied largely between sites. Sr, Mn, Cu, and Zn were mainly in the nonresidual fraction. Most sites showed considerable ecological risk; exceptions were site S7(very high) and sites S10,S11, and S14(moderate). Cu showed moderate-to-high pollution and Pb exhibited no-to-low pollution, while other metals had a non-pollution status according to their ratios of secondary phase to primary phase(RSP). Results of two assessment methods showed moderate pollution and a veryhigh ecological risk for Cu, Zn, Ni, and Cr at site S7, which might be due to the local sewage treatment plant.     

Floodplain effects on the transport of dissolved and colloidal trace elements in the East Pearl River,Mississippi

Substantial work suggests that floodplain wetlands could play a role in modifying fluvial fluxes of dissolved and colloidal trace elements. Yet, few studies have directly addressed this issue. We examined trace elements in the East Pearl River (Mississippi or Louisiana, USA), which is surrounded by wetlands that are temporally more or less connected to the river depending on river stage. Dissolved and colloidal trace element samples, along with ancillary data, including dissolved organic carbon and nutrients, were collected during eight surveys of this system at different flow stages from November 2007 to September 2008. Hydrology of the system is complex due to seasonal changes in water sources as well as potential inputs from the floodplain wetlands and the hyporheic zone. We therefore considered effects including nonconservative mixing of water sources, saltwater intrusion, and floodplain wetland flux requirements needed to support observed downstream concentration changes. During moderately high discharge, fluxes of many elements (e.g., Cd, Fe, Mn, and Zn) increased downstream by 20% or more, with inputs from the floodplain wetlands as the apparent source. At the highest discharge, however, wetland inputs to the river may have been rate‐limited (i.e., the wetland source was flushed faster than biogeochemical processes could regenerate dissolved or colloidal material). At low discharge, other effects, including saltwater intrusion and hyporheic zone interactions, are important. Both redox processes and organic ligands (or dissolved organic carbon), along with the supply of wetland inputs (or removal) relative to river fluxes, appear to be key factors determining floodplain wetland effects. While the behavior of some elements suggests they were dominantly affected by redox processes (Mn and V) or by organic complexation (dissolved Fe and light rare earths), other elements were affected by more than one process in ways that remain obscure (Cu). Overall our results are broadly consistent with previous field, laboratory, and modeling studies and suggest that a better understanding of the sources and transformations of Fe is a key area for future research.     

The Apure River: geochemistry of major and selected trace elements in an Orinoco River tributary coming from the Andes,Venezuela

The analysis of physicochemical variables and selected dissolved elements was performed on the Apure River waters for 15 months. The variables pH, alkalinity, dissolved O₂, conductivity and Na, Ca, Mg and Cd concentrations showed maximum values during low water, whereas K, Si, Fe, Al, Mn, Zn, Cu, Cr and dissolved organic carbon (DOC) showed maximum concentrations during rising and high water. Five important factors were found to control the amount and temporal variability of the dissolved elements: lithology, hydrology, vegetation–floodplain processes, redox conditions and organic complexation. Weathering of silicates, carbonates and evaporites in the Andes provides most of the proportion of Na, Ca, Mg and HCO₃^? to waters. The temporal variability of these ions is controlled by a dilution process. Although Si can be taken up by the biomass, Si and K can be leached from the floodplain by weathering of clays. Microbial decay of the submerged plants in the floodplain during the inundation periods provides DOC and K to river waters and changes the redox conditions in water. The changing redox conditions control the solubility of Mn, Zn and Fe. Dissolved Mn is a function of pH‐dependent redox process, whereas Zn solubility is controlled by scavenging of Zn during the oxidation of Mn²⁺ to MnO₂. Positive relationships between Al, Fe, Cu, Cr and DOC suggest that these elements are complexed by organic colloids generated in the floodplain. Moreover, the binding capacity of Fe with DOC increases under reducing conditions. Although Cd seems to be provided by weathering in the Andes, several processes can affect the mobility of Cd during transport. Copyright © 2010 John Wiley & Sons, Ltd.     

Concentrations of trace elements in marine fish and its risk assessment in Malaysia

Concentrations of trace elements (V, Cr, Mn, Co, Cu, Zn, Ga, Se, Rb, Sr, Mo, Ag, Cd, Sn, Sb, Cs, Ba, Hg, Tl, Pb and Bi) were determined in muscle and liver of 12 species of marine fish collected from coastal areas in Malaysia. Levels of V, Cr, Mn, Co, Cu, Zn, Ga, Sr, Mo, Ag, Cd, Sn, Ba and Pb in liver were higher than those in muscle, whereas Rb and Cs concentrations showed the opposite trend. Positive correlations between concentrations in liver and muscle were observed for all the trace elements except Cu and Sn. Copper, Zn, Se, Ag, Cd, Cs and Hg concentrations in bigeye scads from the east coast of the Peninsular Malaysia were higher than those from the west, whereas V showed the opposite trend. The high concentration of V in the west coast might indicate oil contamination in the Strait of Malacca. To evaluate the health risk to Malaysian population through consumption of fish, intake rates of trace elements were estimated on the basis of the concentrations of trace elements in muscle of fish and daily fish consumption. Some specimens of the marine fish had Hg levels higher than the guideline value by US Environmental Protection Agency (EPA), indicating that consumption of these fish at the present rate may be hazardous to Malaysian people. To our knowledge, this is the first study on multielemental accumulation in marine fish from the Malaysian coast.     

Metal concentrations in water and sediments from tourist beaches of Acapulco, Mexico

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.     

Distribution of dissolved and labile particulate trace metals in the overlying bottom water in the vistula river plume (southern Baltic Sea).

Overlying bottom water samples were collected in the Vistula River plume, southern Baltic Sea, (Poland) and analysed for dissolved and labile particulate (1 M HCl extractable) Cu, Pb, Zn, Mn, Fe and Ni, hydrological parameters being measured simultaneously. Particulate organic matter (POM), chlorophyll a and dissolved oxygen are key factors governing the chemical behaviour of the measured metal fractions. For the dissolved Cu, Pb, Zn, Fe and Ni two maxima, in the shallow and in the deeper part of the river plume, were found. In the shallow zone desorption from seaward fluxing metal-rich riverine particles account for markedly increased metal concentrations, as confirmed also by high particulate metal contents. For Pb, atmospheric inputs were also considered to have contributed to the elevated concentrations of dissolved Pb adjacent to the river mouth. In the deep zone desorption from detrital and/or resuspended particles by aerobic decomposition of organic material may be the main mechanism responsible for enrichment of particle-reactive metals (Cu, Pb, Zn) in the overyling bottom waters. The increased concentrations of dissolved Fe may have been due to reductive dissolution of Fe oxyhydroxides within the deep sediments by which dissolved Ni was released to the water. The distribution of Mn was related to dissolved oxygen concentrations, indicating that Mn is released to the water column under oxygen reduced conditions. However, Mn transfer to the dissolved phase from anoxic sediments in deeper part of the Vistula plume was hardly evidenced suggesting that benthic flux of Mn occurs under more severe reductive regime than is consistent with mobilization of Fe. Behaviour of Mn in a shallower part has been presumably affected by release from porewaters and by oxidization into less soluble species resulting in seasonal removal of this metal (e.g. in April) from the dissolved phase. The particulate fractions represented from about 6% (Ni) and 33% (Mn, Zn, Cu) to 80% (Fe) and 89% (Pb) of the total (labile particulate plus dissolved) concentrations. The affinity of the metals for particulate matter decreased in the following order: Pb > Fe > Zn > or = > Cu > Mn > Ni. Significant relationships between particulate Pb-Zn-Cu reflected the affinity of these metals for organic matter, and the significant relationship between Ni-Fe reflected the adsorption of Ni onto Fe-Mn oxyhydroxides. A comparison of metal concentrations with data from other similar areas revealed that the river plume is somewhat contaminated with Cu, Pb and Zn which is in agreement with previous findings on anthropogenic origin of these metals in the Polish zone of southern Baltic Sea.     

Trace metal variations in the shells of Ensis siliqua record pollution and environmental conditions in the sea to the west of mainland Britain

Shells of the pod razor shell (Ensis siliqua) from 13 locations around the west coast of mainland Britain have been analysed by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for a range of trace metals including Zn, Cd, Pb, U, Ba, Sr and Mg. The trace metal record in these shells is a proxy record for changes in seawater chemistry during the 1990s. Regional variations exist in the median concentrations of the analysed metals. Barium concentrations are related to increased productivity from sewage sludge dumping at sea. Strontium shows a local relationship to salinity, but there is no clear relationship over the study area, instead high Sr is often associated with high Ba, and may reflect ontogenetic factors such as growth rate. Magnesium shows a seasonal variation within individual shells and can be used to calculate sea surface temperatures from groups of shells. Contaminant metals show a clear regional relationship with known sources, thus high Pb and Zn are typically associated with former metal mining areas (e.g. Cardigan Bay, Anglesey), and high Pb, Zn, Cd and U are associated with industrial activity in Liverpool Bay. Anomalies such as the high U in shells from northern Scotland cannot at present be explained. A seasonal variation of Pb is also seen in Cardigan Bay and Liverpool Bay, relating to increased winter fluxes of these metals to the marine environment. The regional distribution of these metals is consistent with known sources of contamination and patterns of seawater migration around the coast of Britain.     

Experimental simulation of chemistry transformation of anaerobic water during aeration

Experiments were carried out to simulate the transformations of anaerobic freshwater chemistry at aeration. Quantitative characteristics of the passage from dissolved into suspended state in the course of aeration were obtained for Fe, Mn, Co, Ni, Cu, Zn, Cd, Ag, Rb, Cs, Sr, Ba, Be, Al, Ga, Cr, Ti, Zr, U, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Lu, B, V, Ge, As, Mo, and W. The decrease in the concentration of dissolved forms was found to be maximal for Fe and Mn, reaching 0.03 and 0.2 mg/L, respectively; these values correspond to the solubility of newly-precipitated oxihydrates of those elements. Among other elements, a high degree of removal is typical of elements-hydrolysates (Cr, Zr, Al, Ga, Be, Ti, and the majority of rare-earth elements), some heavy metals (Zn, Ag, Cd, and Co), and W.     

Investigations on Mineralogical and Chemical Composition of Suspended Particulate Matter (SPM) in the Odra Estuary

In order to recognize lateral and seasonal variations in composition of suspended particulate matter (SPM) in the Odra Estuary, samples were taken at four sites in the period July 1996 - July 1997 monthly if possible. The contents of the elements Si, Ti, Al, Fe, Mn, Mg, Ca, Na, K, P, C, S as well as Ba, Cr, Sr, V, Zn, Cu, Zr, and of the minerals illite, chlorite, smectite, kaolinite and others have been determined. The decreasing influence of the river Odra towards the open sea could be realized with the help of the contents of the minerals quartz, smectite, and of the elements Ba, Cr, K, P, Si and other. 60% of the seasonal and lateral variations can be explained by changing contents of total carbon (TC), total organic carbon (TOC), Al, Fe, Si, Ti, P, Mn, and Ba. They are mainly caused by differences in the production of organic matter, resuspension, riverine input, and redox-sensitive processes.     

The distribution of trace metals in Florida Bay sediments

The distribution of trace metals based on surface sediments collected at 40 stations across Florida Bay was done in June, November and February 2000-2001. Concentrations of Sc, V, Ba, Cd, Cr, Co, Cu, Pb, Mn, Ni, Zn, Al and Mg were determined by ICP-MS, and the total Fe was determined by spectrophotometry. Organic carbon (OC), nitrogen (N), and calcium carbonate (CaCO3) were also measured. Eleven of 13 metals showed a similar distribution pattern for the various months studied. Maximum concentrations of metals were lower than those found in most estuarine systems and were concentrated in the north-central and western zones of the Bay. The Mn and Fe concentrations, unlike the other metals, gradually decreased from north (Everglades) to south (Florida Keys). Some metals (Ni, Zn, Cu, Cr, Pb and Ba) associated with petroleum use showed high concentrations at stations near the Tavernier marina. Florida Bay sediments are predominately CaCO3 (65.9-92.5%). The greatest value for OC (5.5%) and the lowest value of CaCO3 (65.9%) were found in the western zone. Trace metal distribution patterns are similar to the OC and N in the sediments. There was a strong correlation between most metals (V>Cu>Ni>Cr>Al>Co>Ba>Zn>Pb>Mg) and the percentage of OC. The maximum C/N values (9-12) were observed at the stations with the highest OC, where dense colonies of seagrass are found and most of the metals are concentrated. All metals except Mg, Mn and Co showed a strong correlation with Al and the fine fraction of the sediments (aluminosilicates) associated with continental input and river runoff.     

Accumulation features of trace elements in mass-stranded harbor seals (Phoca vitulina) in the North Sea coast in 2002: the body distribution and association with growth and nutrition status

Body distribution and growth- and nutritional status-dependent accumulation of 21 trace elements were investigated in harbor seals (Phoca vitulina) stranded in the North Sea coast in 2002. Higher concentrations and burdens of Mn, Se, Mo, Ag, Sn, Hg, and Bi in the liver, Cd in the kidney, As in the blubber, and Co, Sr, and Ba in the bone were observed. Significant positive correlations of hepatic Se, Mo, Ag, Cd, Sn, Hg, Tl, and Bi with standard body length were found, while significant negative relationships were detected for Mn, As, Rb, Sr, and Sb in the liver. Concentrations of Co, Se, Sr, Sn, Hg, and Bi in the liver, V, Sr, Ag, Sn, and Hg in the kidney, V, Mn, Co, Rb, Sr, Sn, Ba, and Pb in the blubber increased with decreasing blubber thickness of harbor seals, indicating enrichment of these elements in the target tissue by emaciation.     

Dissolved and particulate trace metals in meltwater from the Rhône glacier

Glacial meltwater and sediment at the source of the River Rhône have been analyzed to determine: 1. the partitioning of Al, Cd, Co, Cu, Cr. Fe, Mn, Ni, Pb and Zn between the water and particulate phase. 2. the particle size ranges which affect the dissolved trace metal ion composition of the meltwater and 3. the availability (potential release) of the ten trace metal ions from the sediment. Greater than 80% of the total Cd, Cu, Mn, Ni and Zn were found to be in operationally-defined (0.4 μm) dissolved forms. Fe and Al in the meltwater are primarily associated with particles in the size range 0.4–8 μm, while Cd. Cu, Mn, Ni and Zn occur with particles smaller than 0.1 μm. For the sediment, Cu, Ni and Pb were significantly present as exchangeable forms; only Cu, Ni, Pb and Zn were determined as organicallybound forms.     

Baseline levels of heavy metals in the waters and sediments of Baffin Bay

Baseline levels of a number of trace metals have been determined in samples of water and sediment from Baffin Bay. Concentrations of Cr, Mn, Fe, Ni, Cu and Cd in the waters of Baffin Bay are generally lower than those observed in eastern Canadian coastal waters, levels being close to reported open ocean concentrations. Nearshore sediment samples, analysed for Cr, V, Mn, Ni, Co, Cu, Zn, Hg and Pb, display comparable concentrations to unpolluted muds in eastern Canadian coastal regions. Concentrations of these elements in the deep sediments of central Baffin Bay closely resemble levels in Atlantic Ocean deep-sea clays.     

Elements in size-fractionated bottom sediments of the Elbe River in its Czech part

The concentrations of 45 elements, and the content of organic substances, amorphous inorganic substances and minerals were determined in 26 samples of Elbe River bottom sediments to determine the correlation between the element composition and the grain size in the ￡ \le 4, 4--8, 8--16, 16--32, 32--63 7m and bulk samples ￡ \le 63 7m fractions. The purpose of this study was to obtain information about the role of particle size and their mineral composition as a control of element concentrations in sediments, the potential remobilization of elements under changing environmental conditions, and the chemical speciation of the large excess concentrations of elements in this system.¶About 22--56% of the estimated element yield was associated with sediments with a grain size of less than 4 7m and 82--97% of the element yield was found in the fraction smaller than 32 7m. Sequential extraction carried out for 20 potentially reactive elements in the ￡ \le 63 7m bulk samples and the ￡ \le 4 7m fraction showed the increased importance of exchangeable ions in the order Mn = Ni < Mg < Sr < Cu < Zn < Ca < K < Cd < Na < Mo, reducible fractions Zn < Sr < Mo < Co < Cu < Ni < Pb < Mn < Cr < Be < V = Fe < As < Ag, oxidizable chemical phases As = Ca < Cd < K < Sr < Fe = Mn < Zn = Mg < Mo < Co = Ag < Pb < Li < Cu = V < Ni < Cr = Na < Be with small concentrations from lithogenic phases Mn < As < Pb < Sr < Zn = Cu = Na < Be < V < Ni < Cr < Fe < K < Mg < Li. The major accumulative phases were identified for the individual elements.