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PubMed1996

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

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 power-curve 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.

Analysis of Variance↗

PubMed1992

Factors affecting trace-metal bioaccumulation in Finnish headwater lakes.

Fourteen unpolluted Finnish headwater lakes with pH values varying from 4.8 to 7.0 were studied for trace-metal concentrations in water, sediment, aquatic plants (Nuphar luteum L., Sparganium sp.), aquatic insect larvae (Limnophilus sp., Phryganea sp.) and fish (Esox lucius L., Perca fluviatilis L., Coregonus sp., Salvelinus fontinalis L., Salmo trutta L.). Trace-metal deposition was estimated by analysing the snowpack. Non-parametric correlation analysis was carried out between trace metal concentrations in biota and pH, ANC, TOC, CA + Mg concentration in water and a given metal concentration in water and sediment. Bioaccumulation of several trace metals increased with increasing acidity and decreasing ANC in water. This was especially true for Pb and Cd. Aquatic plants were, in general, the best indicator group concerning differences in trace-metal bioaccumulation in lakes with different acidity. There was some evidence that a higher concentration of TOC in water may reduce bioaccumulation of Pb, Cd and Zn in aquatic plants and fish. The copper concentration in sediment was the only background variable explaining Cu concentration in aquatic insects. Multivariate analysis of the whole background data gave comparable preliminary results. Over 80% of the trace metal concentrations in biota of different lakes was explained by the background variables. In general, elevated concentrations of most of these trace metals can be expected to occur in the biota of acidified low calcareous lakes.

Journal Article↗

PubMed1986

Trace metals and neoplasia.

Numerous trace metals induce cancerous growths in various animal species in vivo and cause mutagenic or chromosomal transformations in cells-cultured cells in vitro. The most potent is probably nickel. The present review indicates that arsenic, cadmium, chromium, nickel and probably beryllium are associated with malignant neoplasms in humans. Inhalation of these metals during processing at refineries has lead to a greater incidence of pulmonary carcinoma as well as other forms of cancer. There is an inverse relationship between the amount of selenium in the environment and the death rate from cancer in humans. Evidence is presented in this review indicating that mutagenic metal ions alter the fidelity of DNA synthesis. This has been demonstrated with purified DNA polymerases using both synthetic and natural DNA templates in vitro, and by mutagenic or carcinogenic effects in vivo. The need for further studies of the molecular effects of metal ions on DNA replication, RNA transcription and translation is indicated by these results.

Animals↗

PubMed2001

Dredging-related mobilisation of trace metals: a case study in The Netherlands.

Mobilisation of contaminants is an important issue in environmental risk assessment of dredging projects. This study has aimed at identifying the effects of dredging on mobilisation of trace metals (Zn, Cu, Cd and Pb). The intensities and time scales of trace metal mobilisation were investigated during an experimental dredging project conducted under field conditions. The loss of contaminated dredge spoil is mainly reflected by increasing levels of trace metals in the suspended matter, dissolved trace metal concentrations in the water column are not significantly influenced by the dredging activities. This indicates a strong binding mechanism of trace metals to the solid phase or a fast redistribution over sorptive phases in response to oxidation of e.g. trace metal sulphides. Given the differences in levels of reactive phases (Mn, Fe, sulphides and organic matter) between the riverine suspended matter and the sediments, changes in the levels of these parameters in the suspended matter upon dredging may give information on the processes influencing the behaviour of trace metals and on the potential loss of sediment during dredging operations. Therefore, we recommend to routinely measure these parameters in studies on contaminant behaviour related to dredging activities.

Cadmium↗

PubMed2002

Distribution and partitioning of trace metals in sediments of the lower reaches of the New Calabar River, Port Harcourt, Nigeria.

The distribution of trace metals in sediments of the lower reaches of the New Calabar River, Nigeria was evaluated together with the partitioning of their chemical species between five geochemical phases. Samplings were made in five zones at the lower reaches of the New Calaber River. All the trace metals were determined by AAS after selective chemical extractions and concentrations given in microg gm(-1) (dry weight basis). The average total concentrations found for trace metals in the sediment were ( mean +/- rsd.) Pb: 41.6 +/- 0.29, Zn: 31.60 +/- 0.42, Cd: 12.80 +/- 0.92, Co: 92 +/- 0.25, Cu: 25.5 +/- 0.65 and Ni: 3.2 +/- 0.25. Maxima and minima concentrations are inconsistent with previous studies in other rivers of this region. Spatial distribution revealed that the sources of trace metals into the river appeared to be of non-point. Five contamination indices were applied in studying the partitioning of the trace metals in the sediment. These indices provided bases for ascertaining the potential environmental risk of trace metals in the river system. The results denote high partition levels in the more mobile and more dangerous phases.

Environmental Monitoring↗

PubMed1982

Effect of trace metals on growth of Streptococcus mutans in a teflon chemostat.

Correlations between the presence of certain trace metals in dental enamel or in drinking water and the incidence of human dental caries have been demonstrated; therefore, the effects of several trace metals on growth of the cariogenic organism Streptococcus mutans OMZ176 were determined. For continuous growth in a chemically defined medium (treated with Chelex-100 to lower trace metal contamination and supplemented with high-purity trace metal salts) used in a chemostat constructed of Teflon, S. mutans required input of carbon dioxide and supplementation with magnesium (126 microM) and manganese (18 to 54 microM). Addition of iron (3.6 microM) increased the level of steady-state growth by a factor of 2.8 (stimulation index [SI]); zinc at 0.4 microM nearly doubled equilibrium growth (SI = 0.9). Higher concentrations of iron and zinc (5.4 and 0.8 microM, respectively) were less stimulatory (SI values of 1.95 and 0.3, respectively). Small (but statistically significant) increases in steady-state growth were effected by cobalt (SI = 0.3 at 5.1 to 20.4 microM) and tin (SI = 0.4 at 5.1 to 10.2 microM). These data suggest nutritional requirements for these metals. Copper at a concentration of 0.16 microM was inhibitory. These results show significant effects of these metals on growth of S. mutans and may confirm epidemiological evidence suggesting a role for certain trace metals in the incidence of dental caries.

Bacteriological Techniques↗

PubMed2002

Preservation and determination of trace metal partitioning in river water by a two-column ion exchange method.

A one-step preconcentration method using two columns in series was used to partition trace metals in natural waters into several operationally defined fractions. The water passed through a Chelex-100 cation exchange column to collect dissolved labile trace metals and then through an AG MP-1 macroporous resin column to collect trace metals complexed with natural organic matter. A third fraction (inert) was obtained from the difference between total dissolved trace metal concentrations, determined after UV irradiation of a separate aliquot, and the sum of the fractions retained on the two columns. This analytical scheme was successfully applied to the determination of Al, Cd, Co, Cu, Fe, Mn, Ni, Pb, V, and Zn in river waters collected from across the state of Texas. Trace metal partitioning between fractions was found to be stable for at least 8 days after the addition of ammonium acetate buffer (pH 5.5). In most samples collected from relatively pristine sections of Texas rivers, the sum of fractions retained on the two columns accounted for better than 80% of the total dissolved trace metal concentrations. In rivers where anthropogenic inputs were more evident (San Antonio and Trinity Rivers), the inert fraction became pronounced, in some cases accounting for up to 95% of the total dissolved concentrations. The preconcentrate is free of matrix interference and can be easily analyzed by atomic absorption spectrometer or inductively coupled plasma mass spectrometer. Using a 1-L sample allows preconcentration factors of 150 or higher for both labile and organic fractions, and therefore, trace metal concentrations and speciation in natural waters at ambient levels can be accurately and precisely determined.

Cation Exchange Resins↗

PubMed1983

Some nutritional aspects of trace metals.

A brief outline of the known biochemical roles of manganese and chromium is given before the problems of determining human trace metal status are discussed. The factors predisposing to trace metal deficiency are reviewed but particular emphasis is placed upon those which alter the bioavailability of essential trace metals from natural and synthetic diets. This is illustrated by practical examples which show the importance of investigating the bioavailability of the trace metal content of artificial diets used in paediatric care. The results of such studies highlight the need to assess similarly the adequacy of the trace element composition of the many meat substitutes and extenders available currently. Finally, some aspects of trace metal supplementation of intravenous feeding regimens are described.

Animals↗

PubMed2005

Trace metals in seawater and copepods in the ocean outfall area off the northern Taiwan coast.

The distribution, partitioning and concentrations of trace metals (Cd, Cr, Cu, Fe, Mn, Pb and Zn) in seawater, including dissolved and particulate phases, and in copepods in the ocean outfall area off the northern coast of Taiwan were investigated. Normalization of metal concentrations to the background metal concentration to yield relative enrichment factors (EF), which were used to evaluate the contamination of dissolved and particulate trace metals in seawater around the ocean outfall. The EF results indicated that the outfall area was significantly contaminated by dissolved Fe and Zn, and by particulate Fe, Cr, Cu, Pb and Zn. In addition, most trace metals were chiefly in the particulate phase. The average percentage of total metal concentrations (dissolved plus particulate phases) bound by suspended particulate matter followed the sequence Al(95%) = Mn(95%) > Pb(88%) > Cu(86%) > Fe(72%) > Zn(32%) > Cr(17.5%) > Cd(3.4%). Therefore, metal contamination is better evaluated in solid phase than in the dissolved phase. The concentration ranges of trace metals in the copepods, Temora turbinata, Oncaea venusta and Euchaeta rimana, near the outfall were: Cd, 0.23-1.81 microg g(-1); Cr, 16.5-195 microg g(-1); Cu, 14-160 microg g(-1); Fe, 256-7255 microg g(-1); Mn, 5.5-80.8 microg g(-1); Pb, 2.6-56.2 microg g(-1); Zn, 132-3891 microg g(-1); and Al, 0.21-1.13%. Aluminum, and probably Fe, seemed to be the major elements in copepods. The concentrations of trace metals in copepods, especially Temora turbinata, near the outfall were generally higher than those obtained in the background station. The mean increase in bioconcentration factor of metals in copepods ranged from 4 to 7 and followed the sequence Al(6.4) > Cu(6.2) > Fe(6.0) > Zn(5.7) > Pb(5.6) > Cr(5.5) > Cd(5.1) > Mn(4.7). Therefore, marine copepods in the waters of northern Taiwan can accumulate trace metals over background concentrations and act as contamination indicators.

Animals↗

PubMed2026

Microbial membrane transporters reveal trace metal niche adaptation in distinct water masses of the Southern Ocean.

BACKGROUND: Trace metals are co-factors for enzymes that are essential for microbial metabolism and the cycling of major elements. Membrane transporters allow microbes to sense and react to trace elements in the environment and to balance their uptake and export for the regulation of intracellular metal homeostasis. The acquisition and efflux of trace metals could lead to reciprocal feedbacks between microbes and the surrounding environment. Whether these processes vary among trace metals and across habitats is presently not known. We used membrane transporters into and out of the cell as indicators for the uptake and efflux of trace metals and provide a detailed picture of the distribution of the respective genes in distinct provinces in surface waters and in subsurface water masses across a transect in the Southern Indian Ocean. RESULTS: We observed marked spatial and vertical patterns in normalized gene abundances of transporters of iron (Fe), manganese (Mn), nickel (Ni) and copper (Cu). Changes in gene abundances were specific to the type of transporter and trace metal, and pronounced differences between surface and specific water masses emerged. We found an enrichment in genes related to efflux and homeostasis of Fe, Ni and Cu in two water masses of the deep ocean that are North Atlantic Deep Water (NADW) and Lower Circumpolar Deep Water (LCDW). This pattern was observed on the community level and for metagenome-assembled genomes (MAGs) affiliated with Alteromonadaceae and Burkholderiaceae that were abundant in these two water masses. CONCLUSIONS: The enrichment in trace metal efflux and resistance genes points to microbially mediated processes, exerted by homeostasis, with potential influence on the trace metal speciation and distribution in specific water masses in the deep ocean. The gene repertoire and distinct distribution pattern of the taxa identified as potential key players could reflect an adaptation to these old water masses with trace metals acting as selective driver. Video Abstract.

Membrane Transport Proteins↗

PubMed2006

Atmospheric dry deposition of trace metals in the coastal region of Los Angeles, California, U.S.A.

Emissions of trace metals to the atmosphere and subsequent deposition, either directly to a waterbody surface or indirectly to the watershed as washoff during rainfall, represents a potential source of contamination to surface waters near urban centers. The present study provides measurements of atmospheric concentrations of particle-bound trace metals, and it estimates the dry deposition mass loading of trace metals in coastal watersheds in the Los Angeles, California, USA, air basin. Coarse-particle atmospheric concentrations of metals were measured seasonally using a Noll Rotary Impactor at six urban sites and one nonurban site. Dry deposition fluxes were calculated by summing the product of air concentration and the theoretical deposition velocity for each particle size fraction. Mean fluxes at urban sites ranged from 3.2 to 9.1, 11 to 34, 3.8 to 8.8, 8.3 to 29, and 69 to 228 microg/m2/d for chromium, copper, nickel, lead, and zinc, respectively. Mean concentrations and fluxes were significantly higher at urban sites compared with the nonurban site, although differences between urban and nonurban sites were reduced when sampling took place within 5 d after rainfall. Dry deposition to watershed land surfaces was substantial, representing a potentially large source of trace metals based on comparisons with load estimates from stormwater runoff.

Air Pollutants↗

PubMedDate not supplied

Trace metal content of cerebral vessels in American Blacks, Caucasians and Nigerian Africans.

Trace metal contents of cerebral vessels in age-matched and sex-matched subjects from three population groups were estimated. The trace metals included calcium, manganese, zinc, magnesium, copper and iron. The American blacks in Washington, D.C., who are ethnologically related to Nigerian Africans, have different patterns of trace metal contents in their cerebral vessels and the observed levels also differed in some respects from Minnesota Caucasians living in a similar environment. The greatest amounts of calcium, zinc, and copper were found in the vessels of American blacks while the greatest amount of magnesium was found in vessels of Minnesota Caucasians. There was no statistically significant difference in the manganese content of the cerebral vessels in three population groups. Nigerian Africans had the least amounts of copper and magnesium but had the highest iron content. A similar high level of iron was observed in the vessels of American blacks. Since it has been shown that American blacks have the most extensive and severe degree of atherosclerosis among the three population groups, it would appear that iron, calcium and manganese in the cerebral vessels may not directly relate to the severity of cerebral atherosclerosis. Relatively high levels of copper and magnesium, which were observed in the cerebral vessels of American blacks and Caucasians, may be of significance in the pathogenesis of cerebral atherosclerosis. The low levels of the trace metals in Nigerians may be protective. The possible role of zinc requires further studies.

Black or African American↗

PubMed2000

Persistent Impacts of Trace Metals from Mining on Floodplain Grass Communities Along Soda Butte Creek, Yellowstone National Park.

/ In Yellowstone National Park, tailings and associated trace metals from past mining have been deposited along 28 km of Soda Butte Creek by large flood events. This study documents grass species diversity, density, and biomass; trace metal concentrations in soils; and soil pH, salinity, and clay content in four selected floodplain meadows contaminated by these tailings. Trace metal levels frequently exceed acceptable concentrations for agricultural soils at sampling points within the meadows. pH levels within flood-deposited tailings are strongly to moderately acid, while pH levels outside of tailings deposits are neutral. The data analysis: (1) shows that metals and acidity associated with tailings affect plant biomass, density, and diversity; (2) documents that the vegetation/metal and vegetation/pH associations are more of a threshold than a linear relationship; and (3) suggests that other factors may be involved in structuring the community. Vegetation diversity, density, and biomass decrease at threshold levels of trace metal concentrations and soil pH in all four meadows. CuSum plots of diversity in relation to trace metal levels show a decrease in mean diversity at 315 ppm copper, 22 ppm arsenic, 4.2% iron, 65 ppm lead, and 170 ppm zinc. Densities of Phleum pratense and Poa pratensis were significantly lower (P </= 0.001) on plots with more than 250 ppm copper. Above-ground biomass of Phleum pratense was also significantly lower on plots with copper levels above 250 ppm. Decreased mean grass density was found on plots with pH < 6.4, but the only statistically significant difference was for Juncus balticus, which had increased density on plots with pH < 6.4. In contrast to the clear impacts of trace metals and pH on vegetation, other site characteristics did not alter measured vegetation characteristics.

Journal Article↗

PubMed1987

Interaction of trace metal contaminants on hematological responses: influence of infection with Trypanosoma lewisi.

The influence of trace metal contaminants (lead, cadmium, and mercury) on Sprague-Dawley rats was investigated to determine whether subclinical levels of these metals might have adverse effects on the host's ability to respond to an infective agent.In the present study, a trace metal contaminant-trypanosome system was employed to observe the hematological changes in rats infected with Trypanosoma lewisi. The animal groups were: (1) lead (Pb), (2) cadmium (Cd), (3) mercury (Hg), and (4) controls (animals not exposed to trace metals).Regardless of the trace metals, infected animals showed decreases in total erythrocyte counts and lower hematocrit values. Generally, infected animals also showed increases in total leucocyte counts, decreases in the percentages of lymphocytes and monocytes, increases in percentage of neutrophils, and no changes in percentages of eosinophils and basophils.

Animals↗

PubMed2005

Recovery and distribution of biosolids-derived trace metals in a clay loam soil.

The long-term mobility of trace metals has been cited as a potential hazard by critics of EPA 503 rule governing the land application of biosolids. The objectives of this study were to assess the accumulation of Cu, Ni, Cd, and Zn within the soil profile; the distribution of exchangeable, specifically adsorbed, organic, and oxide fractions of each metal; and mass balance of Cu, Ni, and Zn 17 yr after a single biosolids application. Biosolids were applied to 1.5- x 2.3-m confined plots of a Davidson clay loam (fine, kaolinitic, thermic Rhodic Kandiudult) in 1984 at 0, 42, 84, 126, 168, and 210 Mg ha(-1). The highest biosolids application supplied 4.5, 750, 43, and 600 kg ha(-1) of Cd, Cu, Ni, and Zn, respectively. Soils were sampled to a depth of 0.9 m and sectioned into 5-cm increments after separating the Ap horizon. Total (EPA-3050B), bioavailable (Mehlich-I), sequential extraction, and dispersible clay analyses were performed on samples from the control, 126 Mg ha(-1), and 210 Mg ha(-1) treatments. Trace metals are still concentrated in the top 0.2 m with slight enrichment down to 0.3 m. More than 85% of applied Cu, Ni, and Zn are still found in the topsoil where biosolids was incorporated and 95% or more of the applied metals were accounted for with mass balance calculations. Mehlich-I results showed a slight increase in metal concentration down to 0.35 m. Biosolids application increased the concentrations of trace metals in all the extracted fractions. The major portions of Cu, Zn, and Ni are associated with the metal-oxides fraction. Dispersible clay content and water-soluble metal contents were low and except for water-soluble Zn they were not affected by biosolids application. Results from this study showed that 17 yr after biosolids application there was negligible movement of trace metals through the soil profile and consequently there is little risk of contamination of ground water at this site.

Aluminum Silicates↗

PubMed2002

Trace metal sorption ability of insolubilized humic acids.

The objective of this work was to study the trace metal sorption ability of Insolubilized Humic Acids (IHA) in comparison with regular Humic Acids (HA). IHA were prepared from HA by heating at 330 degrees C for one hour under a nitrogen atmosphere. A solubility study was carried out at different pH values in NaNO3 (0.1 M) as a background electrolyte. It showed that IHA were insoluble until pH 10 whereas the solubility of HA increased with pH in one main step in the pH range 4-5 over which the soluble fraction of humic acids increased from 10% to 90%. We observed that trace metal sorption was dramatically influenced by these solubility properties. Indeed this study showed that above pH 5-6, HA and IHA may have opposite effects in terms of trace metal sorption. Solubilization of HA made possible the formation of soluble metal-humic complexes, retaining metal in solution even for pH at which hydroxide can form. Under such pH conditions, which very numerous soils show, HA could be involved in the transport and uptake of trace metals in the plant-soil system. In terms of remediation, HA are not a suitable binding phase. On the contrary IHA were not solubilized at neutral and alkaline pH, avoiding then the solubilization of sorbed trace metals. They appeared to be a suitable binding additive phase for future remediation trials.

Adsorption↗

PubMed2001

Sources, distribution and variability of airborne trace metals in La Plata City area, Argentina.

Airborne particulate trace metals have been measured bimonthly during day and night hours in four permanent stations located in residential, industrial and commercial sectors of La Plata City region, to characterize the sources and variability of atmospheric inputs. Airborne trace metal regional averages (Pb 64 +/- 62, Cu 30 +/- 27, Mn 26 +/- 20, Zn 273 +/- 227, Fe 1183 +/- 838, Ca 5343 +/- 3614, Mg 1472 +/- 967, Cr 4.3 +/- 2.4, Ni 3.2 +/- 3.5 and Cd 0.41 +/- 0.42 ng/m3) are comparable to the values reported for not grossly polluted cities and below the general trend described for urban particulates. Two- and three-way analysis of variance and variance components tests (P < 0.05) were performed to assess the contribution of the diurnal (day vs. night), spatial (inter-station) and temporal (inter-month) components of variability. Trace metal concentrations followed the behavior of total suspended particles with higher concentrations during the day and at the Downtown station and lower at the Residential site. In general, spatial and temporal variations prevailed over diurnal differences. Spatial differences were clearly most significant for Pb, which presented higher values at the Downtown site reflecting the importance of motor exhaust inputs. In contrast, diurnal differences were more important for Mn due to increased dust resuspension during day hours. A seasonal trend with concentrations usually increasing during winter months and decreasing in spring-summer was also detected. Enrichment factors (EF) were calculated to evaluate anthropogenic versus natural element sources. High EF (21-376) were obtained for Pb, Zn, Cd and Cu reflecting the importance of anthropic inputs. The comparison with EF calculated for high-emitting vehicle particle emissions indicated that motor exhausts are the most important source of these elements in La Plata region. In contrast, the EF calculated for Mn, Cr, Ni, Ca and Mg were low (1.3-7.5) suggesting chiefly natural sources, i.e. soil-derived dusts.

Air Pollutants↗

PubMed2001

Trace metal levels in freshwater fish, sediment and water.

The trace metal concentrations in water, sediment and aquatic organisms, such as fish, could indicate the level and tendency of the pollution. This is important not only for the protection of the environment, but for evaluation of the quality of fish meat either captured from natural waters or cultured in fishponds. The total trace metal concentrations in samples of fish from different regions of Hungary and from different species have been determined by using an X-ray fluorescence technique (EDXRF). Water, sediment and fish samples from fishpond systems with different feeding and stocking has also been analyzed. In the case of zinc contents, differences have been traced between the cultured and wild common carp. In the case of common carp reared under different feeding conditions, differences were also observed in the zinc concentration. The retention of the trace metals in the fish has been studied by measuring the levels in sediment, water and feed. The different retention can be explained by the different availability of zinc in the applied feeds, which can be related to the presence of different metal species in the feeds.

Animals↗