Showing papers on "Trace metal published in 1996"

Trace metal composition and speciation in street sediment: Sault Ste. Marie, Canada

Abstract: Street sediment collected in Sault Ste. Marie, Ontario was examined for trace element composition (As, Cd, Cr, Cu, Fe, Pb, Hg, Ni and Zn) and the metal partitioning to various sediment properties was determined by sequential extraction. Total Ni, Cu, Zn and Pb concentrations exceeded the lowest effect levels specified in the Ontario Provincial Sediment Quality Guidelines for Metals (Environment Ontario, 1992) and derived from bioassay studies. According to these Guidelines, the disposal of such sediment has to be guided by environmental considerations. A significant fraction of these metals was extractable in 0.5 N HCl over a 12-hour period and considered as potentially bioavailable. The major accumulative phases of toxic metals in this sediment are exchangeable, carbonate, Fe/Mn oxides and organic matter but the relative importance of each phase varied for individual metals. Approximately 20% of the total extractable Cd is found in each of these four fractions. Pb, Zn and Mn are predominantly bound to carbonates, Fe/Mn oxides and organic matter. Cu shows a high affinity for organic matter and to a lesser extent for carbonates. Elevated levels of Cd, Pb, Cu, Zn, Mn and Cr in the exchangeable and/or soluble phase suggest that sediment associated metals, mobilised from streets in Sault Ste. Marie during runoff and snowmelt, would adversely impact water quality in the receiving waters. However, large fractions of the total metal load are associated with coarser particles which are unlikely to be transported through the drainage system into receiving waters.

Spatial and Temporal Distribution of Trace Metals in Sediments from the Scheldt Estuary, South-west Netherlands

Abstract: The spatial and temporal distribution of trace metals has been studied in sediments of the Scheldt estuary, in order to identify trends in space and time. Sediment trace metal data, obtained by 11 laboratories, were considered for the period 1959–90. It was found that trace metal data obtained by complete sample digestion (e.g. HClO4-HF) were incomparable to those obtained by strong acid leaching (e.g. HNO3-HCl). However, various strong acid leaches were found to yield comparable results for sediment trace metals, except for chromium. Hence, trace metal data obtained by strong acid digestion could be merged into a comprehensive database (except for chromium), which was analysed by an ANOVA procedure. Sediment trace metal contents were normalized against a common standard, based on their grain size fraction and organic matter content. Spatial variations were investigated for four areas encompassing the entire Scheldt estuary within the periods 1978–85 and 1986–90. For one specific area, mid-estuary, trace metal data were studied from 1959 to 1987. For each area and period considered, the sediment trace metal content was calculated at the average percentage

The Conservative Behaviour of Trace Metals (Cd, Cu, Ni and Pb) and As in the Surface Plume of Stratified Estuaries: Example of the Rh ône River (France)

Abstract: Concentrations of dissolved trace elements (Cd, Cu, Ni, Pb and As) were determined over a 4-year period (1987 –91) during contrasting hydrological conditions in a typically stratified system: the Rh one river estuary. Dissolved concentrations in the river water vary by nearly one order of magnitude. Estimated average values (nM) are: As, 26; Cd, 0 ·27; Cu, 35; Ni, 27; and Pb, 0 ·42. They indicate some degree of contamination for Cd, Ni and Pb, as compared to levels in pristine rivers and world averages. Dissolved concentration variations were interpreted in terms of a dilution of two sources of trace metals, i.e. anthropogenic discharges and leaching of surface soils. Concentrations in the river suspended matter (Cd, Cu, Ni and Pb) were measured during one survey (July 1987); comparison with published data also seems to indicate variable inputs to the estuarine zone. The distributions of As, Cu, Ni and Pb are conservative in the Rh one mixing zone, whereas a small excess is sometimes observed for dissolved Cd. On the whole, trace metal concentrations in the suspended matter tend to decrease from the mixing zone to the open sea. They are only weakly controlled by the amount of terrigenous alumino-silicates. A sorption experiment shows that Cd fixation on the suspended matter is enhanced by increased amounts of particulate organic matter. The simultaneous use ofin situandin vitrodistribution coefficients allows an estimation of the partitioning of particulate Cd between the reactive and non-reactive fractions of the suspended matter. This approach would confirm the mobilization of labile Cd in the saline surface plume.

Flexible digestion strategies and trace metal assimilation in marine bivalves

Abstract: -Pulse-chase experiments show that two ma- rine bivalves take optimal advantage of different types of particulate food by varying food retention time in a flexible two-phase digestive system. For example, carbon is effi- ciently assimilated from bacteria by subjecting nearly all the ingested bacteria to prolonged digestion. Prolonging digestion also enhances assimilation of metals, many of which are toxic in minute quantities if they are biologically available. Detritus-feeding aquatic organisms have always lived in environments naturally rich in particle-reactive metals. We suggest that avoiding excess assimilation of metals could be a factor in the evolution of digestion strat- egies. We tested that suggestion by studying digestion of particles containing different Cr concentrations. We show that bivalves are capable of modifying the digestive pro- cessing of food to reduce exposure to high, biologically available, Cr concentrations. The evolution of a mecha- nism in some species to avoid high concentrations of metals in food could influence how effects of modern metal pol- lution are manifested in marine ecosystems.

Trace metals in the central and southern North Sea

Abstract: Measurements of both dissolved and particulate trace metals (Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn) were made on samples collected simultaneously in the central and southern North Sea (below 56°N), during four cruises covering the seasonal cycle. Analyses of trace metals in both phases were undertaken using similar analytical protocols, and the data subjected to rigorous quality controls. Clean techniques were used throughout sampling and analysis. Trace metal concentrations ranged from those characteristic of waters entering the shelf region from the North Atlantic Ocean to values which in some cases were two orders of magnitude higher. Marked increases in concentrations were often associated with waters directly influenced by riverwaters, but the results showed that the distributions could be influenced by processes other than fluvial inputs. The redox-sensitive metals, Fe and Mn, were influenced at some sites, including those overlying areas of fine-grained sediments, by benthic inputs associated with seasonal changes in oxidation-reduction conditions in the benthic interfacial zone. The behaviour of metals which are not redox-sensitive (Cd, Zn) in some cases paralleled those of Fe and Mn, suggesting an association with Mn-or Fe-rich solid phases, or with organic matter. However, seasonal variations in concentrations of Cd and Zn were not directly linked to the cycle of biological utilization and regeneration of nutrients, suggesting that their geochemistry is more influenced by boundary inputs. Resuspension of Pb-rich sediments, long-range transport of Pb-rich suspended particulate matter (SPM), and enhanced, though diffuse, atmospheric inputs of lead were considered to have contributed to the elevated concentrations of particulate Pb (mass metal/mass sediment) in the water column during winter. Estimates of partitioning (K D s) were derived from the dissolved and particulate data for each of the metals over the seasonal cycle. For the more particle-reactive metals (Co, Fe, Mn, Pb), transport in the suspended particulate phase is a significant, sometimes dominant factor. In contrast, for Cd, Cu and Zn, transport in solution will dominate under almost all conditions in the southern North Sea. Furthermore, the values of K D , for a particular metal, varied widely, partly in response to seasonal differences in the relative contributions of lithogenous and biogenous particles to the particles in suspension. Only for Cu and Zn during the winter could the partitioning be described by a narrow range of K D values covering the observed concentrations of SPM. The data from this study give unique information concerning the contemporaneous distribution of dissolved and particulate trace metals in the southers North Sea and they provide a baseline against which the effects of reductions of inputs into the North Sea may be more accurately assessed. Viewed in combination, the dissolved and particulate data have yielded new insights into mechanisms affecting trace metal cycling and transport, essential in the development of coupled hydrodynamic-geochemical models.

Heavy Metals in Different Fishes from the Middle Eastern Coast of Tunisia

Abstract: Considerable information has been reported on trace metal concentrations of various fishes in the Mediterranean area, but there is a lack of data in the concentrations of trace metals in fishes from the southern Mediterranean. For this reason, work was done to establish a baseline of heavy metal concentrations on fishes from the coast of Sfax (middle eastern coast of Tunisia). This coast has been industrialized for many years. Nevertheless, touristic activities have been developing for the last years. This study examines the accumulation pattern of copper, cadmium, and zinc in individual organs (muscle, liver and gonad) of fishes. 18 refs., 1 fig., 4 tabs.

Trace metal concentrations in the surf zone and in coastal waters off Baja California, Mexico

Abstract: Pronounced spatial gradients were observed in trace element concentrations (Cd, Co, Cu, and Ni) in nearshore surf zone (<100 m offshore) and coastal (5−45 km offshore) waters off Baja California, Mexico. The ranges of metal concentrations in those waters were 0.034−0.26 nM for Cd, 0.022−0.59 nM for Co, 0.93−3.6 nM for Cu, and 3.6−6.4 nM for Ni. Metal concentrations exhibited offshore gradients, with the highest levels nearshore. Metal:salinity, metal:nutrient, and metal:metal relationships indicated that the relatively high nearshore concentrations were caused by upwelling (Cd and Ni) and by benthic particle resuspension and diagenetic remobilization (Co and Cu). The relatively low offshore concentration levels appeared to be caused, in part, by the intrusion of oceanic waters from the North Pacific Central Gyre, as evidenced by similarities in the molar ratios of Ag:Cu in coastal waters off Baja California (9.0 × 10-3) and in subtropical oceanic waters off central Mexico (9.6 × 10-3). This was also consi...

Statistical comparisons of heavy-metal concentrations in river sediments

Abstract: Statisticalt tests were used to determine lead, copper, and chromium enrichment in sediments from the Lower Branch of the Rouge River in southeast Michigan, USA. Both absolute metal concentrations and ratios of trace metal to conservative metal concentrations were used to compare sampled sites along the Lower Branch of the Rouge River to background sites in the headwaters region. Concentration ratios were used to reduce the effects of certain chemical and physical characteristics on the level of metal contained in a given sediment. Results from the comparison of sample sites to the background reveal metal enrichment at several sites, particularly along the highly urbanized, downstream section of the river. This section of the Lower Branch of the Rouge River exhibits significant lead and copper contamination, as well as measurable chromium enrichment when using either concentrations alone or ratios as methods of comparison. The areas of metal enrichment appear to coincide closely with areas of known anthropogenic activities. Of particular interest, however, is the enrichment of lead and copper at two upstream sites where the statistical tests suggest an anthropogenic source for the enrichment, but where no previously known cultural activities existed. These data prompted a historical search of records, which discovered several abandoned landfills immediately upstream of the metal enrichment sites.

The Influence of Saharan and Middle Eastern Desert-Derived Dust on the Trace Metal Composition of Mediterranean Aerosols and Rainwaters: An Overview

Abstract: The particulate aerosol over the Mediterranean Sea consists largely of a ‘background’ of European-derived anthropogenic-rich material which has a trace metal composition similar to that over other European coastal seas, but which is subject to sporadic inputs of crustal-rich material from Saharan and Middle East desert sources which are often transported in the form of dust ‘pulses’. The input of Saharan dust results in increases in the total concentrations of crust-controlled trace metals (NEEs), such as Al and Fe, and to decreases in the values of AEEs, such as Cu, Zn and Pb, in the aerosol. Variations in the concentrations of trace metals at any one site in the Mediterranean Sea are largely controlled by: (i) the magnitude of the inputs of crust-rich dusts which are mixed with the anthropogenic-rich ‘background’ material, and (ii) precipitation scavenging, which removes both anthropogenic and crust-rich material from the air.

Regeneration, recycling, and trophic transfer of trace metals by microbial food‐web organisms in the pelagic surface waters of Lake Erie

Abstract: Rapid regeneration of ‘OgCd and 65Zn from their picoplankton prey into the dissolved phase by microzooplankton was observed in water sampled from the pelagic surface waters of Lake Erie (summer 1994 and 1995). Trace metals were added to grazing (lake water < 2’10 brn) and control (lake water CO.2 pm) treatments in the form of radiolabeled Synechococcus, Picoplankton (0.2-3 pm) were grazed heavily by consumers in the nanoplankton (3-20 pm) and microplankton (20-2 10 pm) size classes (collectively referred to as microzooplankton) as confirmed by dilution assays used to independently measure grazing activity. Most consumed trace metals were regenerated into the dissolved phase (x0.2 pm), but some trophic transfer of ‘OgCd and 65Zn from radiolabeled prey into the nanoplankton and microplankton did occur: 65Zn was transferred 2.5 times more efficiently into the microplankton and 2.9 times more efficiently into the nanoplankton than was logCd. Recycling of regenerated logCd back into plankton biomass was greater than that for 65Zn. Grazing by microzooplankton influenced the molecular size distribution of regenerated trace metal in the dissolved phase (77 + 6% log Cd <5,000 MW; 8f24% “5Zn ~5,000 MW). These results show that microzooplankton grazing tends to prolong the residence times of metals such as Cd and Zn in the pelagic surface waters of large lakes.

Uptake of lead by Lemna gibba L.: influence on specific growth rate and basic biochemical changes.

Abstract: In recent years heavy metals have become ubiquitous in the environment due to rapid industrialization and urbanization. Among the heavy metals, lead (Pb) content in water and soil are closely linked with leaded gasoline, lead-based paint, sewage sludges used as fertilizer or land disposal of sewage as well as industrial wastes. The toxicity of lead to aquatic organisms is dependent on pH, water hardness, dissolved oxygen and its ionic form. Several authors reported trace metal concentrations in aquatic points. Submerged macrophytes, algae and bacteria are capable of biomagnifying metal ions several fold over the environment. Removal of nutrients and certain heavy metals from waste water by Lemna gibba L. has been reported by Staves and Knaus, Kwan and Smith and Buckley. The main objective of the present investigation was to study the removal efficiency of lead under continuous and discontinuous illumination using Lemna gibba L. 22 refs., 3 figs., 2 tabs.

The chemistry of Offatts Bayou, Texas: A seasonally highly sulfidic basin

Abstract: Offatts Bayou basin was created by use of this are as a borrow pit for landfill by the city of Galveston, Texas, in the first half of this century. Restricted exchange of water with the adjacent West Bay results in this basin changing, on a seasonal time scale, between oxic winter and highly sulfidic summer (greater than 500 μM ΣH2S) bottom water conditions. It is, therefore, a “natural laboratory” for the investigation of the behavior of toxic metals in an estuarine environment where redox conditions undergo major variations. Here we report the first study of the chemistry of Offatts Bayou’s waters and sediment-associated trace metals. The high concentrations of dissolved sulfide in bottom water during summer cause a loss of macrofauna from most of the water deeper than about 4 m and the bottom of the basin. The potential exists for major mortality of organisms living in the oxic surface waters if rapid mixing of waters were to occur during the summer. Reactions of toxic metals with sulfides are probably the dominant influence on their potential bioavailability in this type of environment, as evidenced by large seasonal changes in concentrations of sedimentary sulfide minerals and associated trace metals. The trace metals As, Cu, and Hg are dominantly found in the pyrite phase (greater than 75% pyritization), Ag and Mn are moderately pyritized (40% to 60%), and Zn is not strongly associated with pyrite (less than 20% pyritization).

Trace metals in populations of freshwater isopods: influence of biotic and abiotic variables.

Abstract: Trace metal levels in water, sediments and freshwater isopods from 28 different water systems in the Netherlands were measured during the period of 1986 to 1989. Distinct element-specific internal distribution patterns were present, with Cd and Cu stored mainly in the hepatopancreas (30–60% of total body burden) and Pb and Zn in the hindgut and exoskeleton with hemolymph. Mean whole-body concentrations of the non-essential elements Cd and Pb in individually analyzed isopods varied over three orders of magnitude between populations. The variability of Zn and Cn were within one order of magnitude difference. The variability of trace metal levels between populations exceeded within-population variability. Within-population variability was related to seasonal and biological factors such as body weight, sex, reproductive state, and species abundance. The highest concentrations were found in small juvenile animals compared to adults, females compared to males, and Proasellus meridianus compared to Asellus aquaticus. However, after correction for size effects using a powercurve regression model no significant differences remained between sex and species. Seasonal fluctuations accounted for 33–79% of the within population variability. Trace metal levels in isopods were predicted from concentrations in water and sediments in combination with aqueous Ca, Cl−, DOC, and sediment characteristics (Org-C, clay, CaCO3) using a multiple regression model. With this predictive model 42–63% of the variance could be explained. In situ determined partitioning coefficients (apparent BCF, biota-sediment BSAF, and sediment-water distribution coefficient Kd) varied between locations and covaried with factors related to trace metal bioavailability (aqueous Ca, Cl− and DOC, sediment Org-C, clay, and CaCO3). Especially for Cd and Cu field-derived BCF values were in agreement with previously reported experimental studies. It is concluded, that A. aquaticus may be a suitable candidate-organism for biomonitoring available trace metal levels in littoral freshwater systems. Finally, some practical recommendations are given for future field surveys with freshwater isopods with respect to sample size, allometric standardization, period of sampling and statistical design.

Composition and Behaviour of Trace Metals in Post-oxic Sediments of the Gulf of Papua, Papua New Guinea

Abstract: Trace metal composition and behaviour were examined in post-oxic muds of the Gulf of Papua in January 1993. Porewater profiles and flux measurements indicate significant Fe and Mn reduction in these coastal muds. Vertical profiles, rates of sediment-water exchange, and correlation analyses imply that these silt-dominated muds mobilize Al and are a sink for Mo. Undetectable or very low porewater concentrations and flux rates of other metals (Ni, Cu, Cr, Co, Pb, Cd) indicate immobilization into solid-phase minerals. Solid-phase metal concentrations are consistent with those in average shale, suggesting pristine conditions in the gulf. Low (<1–2 μM) free sulphides, low clay content, and bioturbation are partly responsible for trace metal composition and concentrations, but several lines of evidence imply non-steady-state diagenesis in these muds: (1) the lack of a clear zonational sequence of solutes with sediment depth; (2) lack of agreement between vertical profiles of dissolved and solid-phases of most metals; (3) significant, but weak, correlations between dissolved metals and dissolved organic carbon, and between solid-phase metals and total organic carbon; and (4) lack of correlation between conservative elements (e.g. dissolved Mo and Cl−; dissolved Al and SiOH). Intense, massive physical reworking is cited as the major factor fostering apparent non-steady-state behaviour of trace metals in the surface muds of the Gulf of Papua. This scenario is very similar to that occurring on the Amazon shelf, and may be typical of other wet tropical regions with high-energy coastlines receiving large amounts of highly weathered, river-borne material.

Organochlorines and trace elements in four colonial waterbird species nesting in the lower Laguna Madre, Texas

Abstract: Eggs from four aquatic bird species nesting on the National Audubon Sanctuary Islands of the lower Laguna Madre were collected during 1993 and 1994 to determine concentrations of organochlorine compounds and trace metals and to evaluate their possible detrimental effects on birds nesting in this aquatic ecosystem. The only chlorinated hydrocarbons found above detection limits were p,p′-DDE (DDE), p,p′-DDT (DDT), HCB, HCH, chlordane, and polychlorinated biphenyls (PCBs). Median DDE and PCB levels in eggs of four species were below 1 μg/g ww. Concentrations of DDE were much greater (6–70 fold) than the concentrations of other chlorinated pesticides which were present at or near detection limits. One egg from a snowy egret contained 9.65 μg/g DDE, 0.056 μg/g DDD, and 1.75 μg/g DDT. Ten heavy metals and trace elements (Hg, Se, B, Cr, Cu, Fe, Mg, Mn, Sr, and Zn) were detected in 90% of the samples but at levels that were not of concern. In 1993–1994, concentrations of DDE in eggs of aquatic birds of the lower Laguna Madre were much lower than levels detected in this area during the late 1970s and early 1980s. Concentrations of DDE, PCBs, and trace metals in eggs detected in this study could not be associated with deformities or other detrimental effects on birds.

The body ion loss biomarker. 1. Interactions between trace metals and low pH in reconstituted coal mine‐polluted water

Abstract: Net body ion loss of brook charr (Salvelinus fontinalis) was evaluated as a biomarker of the potential toxicity of coal mine-polluted water. Fish were exposed in reconstituted coal mine-polluted water prepared in a continuously flowing system with a mixture of 16 water chemistry variables adjusted to match stream concentrations measured in moderately and severely mine-impacted streams. Changes in net body cation (Na + , K + , and Ca 2+ ) loss rates from the fish were determined. Metal/pH interactions were tested by exposing fish to (1) a mixture of all six potentially toxic metals (Al, Fe, Zn, Mn, Ni, and Cd or Pb), (2) individual metals, (3) no metals (low pH effect), or (4) time control. At severe levels (pH m 3.34) all metal treatments caused a net whole-body sodium loss rate similar to that observed for pH alone. Body potassium rates were essentially unchanged from that of the control ; a significant calcium influx observed under control conditions was eliminated by most acid and metal exposures. At less severe pollution levels (pH 3.95) some metals (Ni 2+ , Mn 2+ , and Zn 2+ ) blocked the net loss of body sodium induced by acidity. We conclude that net body sodium loss rate is a sensitive, reproducible, and acute indicator of acid and trace metal pollution and may be a useful biomarker for determining the presence and degree of impact of coal mine-polluted water on fish.

Community Metabolism in Microbial Mats: The Occurrence of Biologically-mediated Iron and Manganese Reduction

Abstract: Community metabolism and nutrient, iron (Fe) and manganese (Mn) cycling were examined in two intertidal, marine, microbial mat communities during short (4–5 days) incubations in closed, flow-through microcosms. Sediment microcosms were incubated under either light (light–dark cycles) or dark (continuous darkness) conditions to assess the effect(s) of photosynthetic oxygen production and microalgal activity on nutrient, Fe and Mn cycling. The effects of chemical redox reactions between reduced sulphur (S), Fe and Mn cycling were examined by blocking sulphate reduction, and reduced S production, with 25 mM molybdate while incubating under dark conditions. In light-incubated microcosms, negligible fluxes of nutrients (nitrogen and phosphorus) and trace metals were observed. A substantial sediment–water flux of reduced Fe (Fe 2+ ) and Mn (Mn 2+ ) was observed in microcosms incubated under continuous darkness; highest fluxes were observed in molybdate-amended microcosms. At both sites, biologically-mediated redox reactions accounted for a substantial (>50%) portion of the Fe 2+ and Mn 2+ flux. Both microbial mat communities exhibited similar rates of gross photosynthetic oxygen (O 2 ) production, but dramatically different rates of net benthic O 2 flux. Distinct patterns of net O 2 production and trace metal cycling arose from differences in either trace metal oxide availability or reactivity (mineralogy), organic carbon mineralization rates, or sediment characteristics (porosity). Variations in the microbial community responsible for trace metal cycling could have also contributed to the pattern. The present data illustrate that chemically-mediated redox reactions between metal oxides and reduced S complicate interpretation of Fe and Mn fluxes, underscoring the need to separate chemical and biological reactions when attempting to determine the role of biological trace metal reduction in organic carbon oxidation.