Showing papers on "Trace metal published in 1998"

Metal metabolism in aquatic environments

Abstract: Mechanisms of metal uptake. The interactions between living organisms and metals in intertidal and subtidal sediments. Microorganisms and the biogeochemical cycling of metals in aquatic environments. Metal accumulation and impacts in phytoplankton. Mercury in aquatic ecosystems. Arsnic metabolism in aquatic ecosystems. Determinants of trace metal concentrations in marine organisms. Metal handling strategies in molluscs. Phylogeny of trace metal accumulation and toxicity in fish. Influence of ecological factors on accumulation of metal mixtures. Metals and marine food chains. Metal accumulation and detoxification in humans.

Effect of Short-Term Resuspension Events on Trace Metal Speciation in Polluted Anoxic Sediments

Abstract: The effects of the short-term resuspension of a contaminated anoxic estuarine sediment on solid-phase metal speciation have been studied. Preliminary experiments investigated the oxidation rates of model metal sulfide phases to provide mechanistic information for interpreting the observations on the natural sediment. FeS and MnS model phases were particularly labile and oxidized rapidly in aerated waters. In contrast, CdS, CuS, PbS, and ZnS model phases were kinetically stable over periods of several hours. The oxidation rate of free sulfide (HS-) was significantly slower than that of FeS and MnS. Upon sediment resuspension, the rapid decrease in acid volatile sulfide (AVS) could be accounted for by the oxidation of iron monosulfide phases. Over prolonged resuspension periods (>300 min), AVS decreased to values lower than the simultaneously extracted metals [SEM = ∑Cd, Cu, Ni, Pb, Zn (1 M HCl extraction, 30 min)] concentration, indicating that a significant fraction of trace metal sulfide phases may be ox...

Trace metals and antioxidant enzymes in gills and digestive gland of the Mediterranean mussel Mytilus galloprovincialis

Abstract: A seasonal variability of trace metal concentrations and antioxidant enzymes was observed in gills and digestive gland of the Mediterranean mussel Mytilus galloprovincialis from both a polluted and a nonpolluted population. Trace metals (As, Cu, Fe, Mn, Pb, and Zn) exhibited, in both organs, maximum values in later winter–early spring followed by a progressive decrease during the summer. While in the gills this behavior probably reflects a different bioavailability of metals, in the digestive gland it is influenced mainly by the progressive infiltration of the organ by gonadic tissues during gametogenesis. Metals, as other pollutants, are known to influence the oxidative status of these organisms and antioxidant enzymes have been often proposed as biomarkers of exposure to contaminants. In this respect, it was of interest to compare the variations of these biochemical parameters with those of metal levels in two mussel populations from a polluted and a nonpolluted site, respectively. The biochemical parameters examined included the level of glutathione and the activity of the following glutathione dependent and antioxidant enzymes: glyoxalase I, EC 4.4.1.5; glyoxalase II, EC3.1.2.6; glutathione S-transferases, EC 2.5.1.18; glutathione reductase, EC 1.6.4.2; Se-dependent, EC 1.11.1.9 and Se-independent, EC 2.5.1.18 glutathione peroxidases; catalase, EC 1.11.1.6; superoxide dismutase, EC 1.15.1.1. Seasonal variations of trace metals did not appear to influence those of biochemical parameters, which generally showed an opposite trend with higher enzymatic activities in summer when trace metal concentrations were lower. The effects of metals on antioxidant enzymes were more evident when the two mussel populations were compared. In particular, organisms from the polluted site showed lower levels of glutathione and higher enzymatic activities of glyoxalase I even though the magnitude of these differences was not constant during the year. Moreover, native mussels from both the polluted and control populations exhibited limited differences in the activities of glutathione reductase, glutathione peroxidases, catalase, and superoxide dismutase, suggesting the possibility of some biochemical adaptation in organisms from chronically polluted environments.

Extractability of Metal Sulfide Minerals in Acidic Solutions: Application to Environmental Studies of Trace Metal Contamination within Anoxic Sediments

Abstract: Sulfide minerals are an important sink for metals within anoxic sediments. Extraction techniques using cold HCl to measure the concentration of sulfide mineral associated trace metals have gained wide acceptance as a proxy for potential metal bioavailability within the environmental community. However, certain metal sulfide phases that can potentially release metals into a more bioavailable phase do not extract in HCl. Laboratory experiments have shown that covellite (CuS), chalcocite (Cu2S), cinnabar (HgS), millerite (NiS), heazlewoodite (Ni2S3), and vaesite (NiS2) are poorly soluble in HCl; while greenockite (CdS), mackinawite (FeS1-x), pyrrohtite (FeS), galena (PbS), and sphalerite (ZnS) are highly soluble in HCl. Surface area can also affect the apparent solubility of CuS and NiS in HCl. These results indicate that use of HCl-based extraction schemes (e.g., AVS/SEM ratios) to assay sediments for metal contamination could underestimate the potential bioavailability of several metals of general interest...

Phylogeny of trace metal accumulation in crustaceans

Abstract: Invertebrates accumulate trace metals in their tissues whether or not these trace metals are essential to their metabolism. Different invertebrates accumulate different trace metals to different degrees and accumulated concentrations vary greatly at tissue, organ and body levels (Eisler, 1981; Depledge and Rainbow, 1990; Rainbow, 1990a, 1993; Rainbow et al., 1990; Phillips and Rainbow, 1993; Chapter 8). Whether an accumulated concentration is high or low, therefore, cannot be assessed on an absolute scale, but the significance of an accumulated concentration depends greatly on the specific tissue and the specific invertebrate (Rainbow, 1987,1988, 1990a, 1993, 1996; Dallinger, 1993). To take one taxon as an example, tissue and body concentrations of trace metals vary greatly in crustaceans, even in the absence of anthropogenic input of trace metal contaminants (Bryan, 1968, 1976; Moore and Rainbow, 1987; Rainbow, 1987, 1988, 1989, 1990a,b, 1993; White and Rainbow, 1987; Ridout et al., 1989). Table 9.1 highlights this interspecific variation in the body concentrations of zinc, copper and cadmium in crustaceans collected from clean and metal-contaminated sites.

Rock−Water Interactions Controlling Zinc, Cadmium, and Lead Concentrations in Surface Waters and Sediments, U.S. Tri-State Mining District. 2. Geochemical Interpretation

Abstract: We have studied principle rock−water interactions that control trace metal concentrations in a complex geochemical environment containing multiple contaminants and multiple solid phases by combining kinetic and thermodynamic evaluation of the water chemistry with spectroscopic analyses of the sediments. This approach allows the number of geochemical reactions needed to model and predict trace metal mobility over a range of natural settings to be greatly constrained. In the U.S. Tri-State Mining District (Kansas−Missouri−Oklahoma) the most important geochemical interactions are degassing of CO2(g)-rich waters; the short-term uptake and release kinetics of zinc, cadmium, and lead; competition between iron oxyhydroxides and carbonates for zinc, cadmium, and lead; and catalysis of sulfide dissolution by iron in near-neutral waters. In our field study, degassing of CO2(g) waters is responsible for the range of pH measured at each site over the 1-year field study. Trace metal release and uptake kinetics by iron...

Determinants of trace metal concentrations in marine organisms

Abstract: The purpose of this chapter is to provide a synthesis of the very extensive literature pertaining to the factors that influence the uptake, accumulation and handling of trace metals by marine biota. For more extensive reviews refer to the key references: Eisler (1981), Fowler (1990), Samiullah (1990), Vernet (1991), Bryan and Langston (1992) and Tessier and Turner (1995). The literature is replete with examples of the quantification of metal concentrations in an array of marine organisms collected from numerous locations. However, it is evident that information concerning the factors that determine the metal burdens of these organisms is patchy, with certain groups more thoroughly investigated than others; for example, contrast the molluscs with macroalgae.

Certified reference material for the quality control of EDTA- and DTPA-extractable trace metal contents in calcareous soil (CRM 600)

Abstract: Single extraction tests are commonly used to study the eco-toxicity and mobility of metals in soils, e.g. to assess the bioavailable metal fraction (and thus to estimate the related phyto-toxic and nutritional deficiency effects) and the environmentally accessible trace metals upon disposal of e.g. sediment on to a soil (e.g. contamination of ground waters). However, the lack of uniformity in the different procedures does not allow the results to be compared worldwide nor the procedures to be validated. This paper describes the interlaboratory testing of EDTA- and DTPA-extraction procedures for soil analysis, followed by the preparation of a calcareous soil reference material (CRM 600), the homogeneity and stability studies and the analytical work performed for the certification of the EDTA- and DTPA- extractable contents of some trace metals (following the standardized extraction procedures).

Vegetative growth and trace metal accumulation on metalliferous wastes

Abstract: A greenhouse study was conducted to investigate the growth of the grass cover crops Agrostis capillaris, Festuca ovina, F. rubra, Lolium perenne, and Phleum pratense and their accumulation of Cu, Pb, Zn, Ni, and Cr in three metal-contaminated wastes arising from a steelworks, a lead mine, and a chemical works. Soil metals were extracted by five reagents (Mehlich 1, 0.1 M HCI, 0.005 M DTPA, 0.005 M EDTA, 0.005 M NTA) and values were correlated with plant tissue accumulation of metals. Agrastis capillaris accumulated the greatest concentration of metals from each waste material. Dry matter production for all grasses decreased on contaminated substrates compared to the control ; however, overall ground cover was satisfactory except for A. capillaris on the chemical works waste. Lolium perenne and P. pratense consistently produced the highest dry matter yields. All grasses accumulated excessive amounts of Cr on the chemical waste and Pb on the mine waste, presumably from reservoirs in the readily extractable and soluble forms. The extractability of most metals was generally 0.1 M HCI > Mehlich 1 > DTPA = EDTA = NTA. Mehlich 1 did not appredably extract Pb from two wastes No extractant was able to represent metal uptake by a particular grass in a linear fashion.

The behaviour of iron and other trace elements during the IronEx-I and PlumEx experiments in the Equatorial Pacific

Abstract: Dissolved ( 5 μm, leachable and refractory) trace elements were measured during the IronEx I and PlumEx experiments in October and November 1993 near the Galapagos Islands. Iron was measured in the enriched patch and at control stations over a 9 day period following fertilization. The dissolved iron was initially depleted at a rate that gave an iron half-life of 28–40 h. The loss rate gradually decreased, and dissolved iron concentrations did not decrease below about 0.25 nmol kg-1 throughout the experiment. These results were most consistent with a kinetic model that was second order in iron concentration for the scavenging removal of each iron fraction. Other trace elements measured did not change significantly either in concentration or partitioning during the IronEx I experiment. Biological production tracked iron concentrations over time, which suggests that productivity within the fertilized patch was regulated by the availability of iron. The PlumEx study consisted primarily of two transects, a meridional course to the east of the Galapagos Islands and a zonal section to the west. Surface dissolved iron was very low at all stations except those near the Galapagos Islands. Sections of trace metal and other properties distinctly confirm the upwelling of the Equatorial Undercurrent as it intersects the islands. This upwelling has a great effect on the surface distributions of the trace metals on the west side of the islands. Productivity within the mixed layer of this region is highly correlated with iron and nitrate. West of the islands highest productivity is found at stations with the highest iron. North of the Equatorial front, in nitrate-depleted waters, elevated iron concentrations do not enhance productivity.

A Novel Voltammetric In-Situ Profiling System for ContinuousReal-Time Monitoring of Trace Elements in Natural Waters

Abstract: This article describes a novel voltammetric in-situ profiling system (VIP System) for continuous, real-time monitoring of trace elements in fresh and seawater down to 500 meter depth. The VIP System has been designed using advanced microprocessor and telemetry technology. The heart of the submersible voltammetric probe is a Hg-plated Ir-based microsensor covered with an antifouling gel membrane. This gel integrated microsensor allows direct voltammetric measurements of trace metals in complex media without physical and chemical interferences of the test solution. A detailed description of the system is given and examples of environmental applications are reported for in-situ trace metal monitoring in oxygen saturated seawater as well as for in-situ profiling of MnII in anoxic lake water. The results indicate that the VIP System is robust and reliable and that in-situ measurements of mobile fraction of trace metals can be achieved down to very low concentration levels (ca. 5 ppt).

Biogeochemical Controls on Trace Metal Cycling in Anoxic Marine Sediments

Abstract: The solid phase chemical speciation of Fe, Cu, Ni, and Zn was investigated in two different biogeochemical environ ments in Chesapeake Bay to quantify the seasonal variability in the concentration of sulfide minerals and associated trace metals in the top 10 cm of sediment. When acid volatile sulfides (AVS) constitute less than 20% of HCl-soluble Fe (“reactive” Fe), the system is dynamic with respect to metals, and the formation and destruction of AVS minerals can potentially result in statistically significant seasonal shifts in both the flux of Cu across the sediment−water interface and the sedimentary concentration of Cu and Zn. When greater than 20% of HCl-soluble Fe is bound within AVS minerals, there is enough sulfide to effectively trap metals within the sediments, and temporal variations in AVS and pyrite do not necessarily result in temporal variations in the concentration of diagenetically available trace metals. Analysis of the ratio of reactive Fe to AVS can potentially increase the reliabilit...

On trace metal geochemistry in the Danube River and western Black Sea

Abstract: Trace metal concentrations were measured in the Danube River estuary and in the shelf area of the north-western Black Sea. Total dissolved concentrations (<0·45 μM) of the freshwater in the river end-member were found to be: Cd=117 pM, Pb=81 pM, Co=266 pM, Zn=6 nM, Mn=19 nM, Ni=15 nM, Cu=36 nM, Al=384 nM and Fe=20 nM. These concentrations are surprisingly low for an area where serious contamination has been suspected. This is particularly true of Cd, Pb and Zn, which are generally anthropogenic in polluted regions. The observed low concentrations, in particular for Fe, Mn, Co and Al can be attributable to the precipitation of hydrated oxides as a consequence of high pH of the Danube River. Concentrations of metals in the particulate fraction are similar to those in other major rivers of the world. The evolution of the total dissolved trace metal concentrations in the surface waters within the salinity gradient suggests: (1) no noticeable exchange between the particulate and the dissolved fraction for Cu, Ni and Zn; and (2) evidence for a low solid to liquid exchange for the other metals (Cd, Fe, Mn, Co and Pb) which brings about a two-fold increase in their concentrations from lower to higher salinity. Another source of dissolved material is suspected at around salinity 15. This source may be from localized-patches in the sediment where specific redox conditions may induce a vertical flux of dissolved metals: the bottom waters above these patches are characterized by a diminution of the dissolved O2and high concentrations of metals. The colloidal fraction (between 10 kD and 0·45 μm) was established on a limited number of samples for Cd, Cu, Mn and Fe and was found to be significant: 40% of Cu, 40% of Cd, ∼50% of Mn and 60% of Fe of the so-called dissolved phase are actually associated with colloidal material. It represents at least 40% of the total dissolved concentration in the fresh water and in the mixing zone. This proportion decreases linearly with salinity for Cd and Cu. Fe is mostly in colloidal form with a maximum (∼80%) between salinity 5 and 10. The surface distribution of the total dissolved metals throughout the study area show a limited influence of the Danube on the concentrations observed for the ‘ open sea ’ (salinity=18). Most of the riverine flux seems to follow the general circulation to the south-west area. These ‘ open Black Sea ’ concentrations are the same order of magnitude as average surface concentrations in the Mediterranean Sea.

Effect of Landfill Leachate Organic Acids on Trace Metal Adsorption by Kaolinite

Abstract: Hexanoic (hex) and fulvic acid (FA), representing early and later stages of landfill leachate evolution, were examined for influence on trace metal adsorption by a poorly crystal lized kaolinite (KGa-2). Our experiments represented a model approach to examine possible reaction mechanisms in an environmentally important ternary metal−ligand−mineral surface system. Batch experiments were conducted in 0.01 mol kg-1 NaClO4 at pH 3−8. Concentrations of metals (Cu, Cd, and Pb) and ligands were representative of those found typically in groundwater immediately downgradient of a landfill. The presence of FA resulted in enhancement of metal adsorption below pH 5, whereas the presence of hex produced no significant net change in metal uptake. Measured surface charge properties of KGa-2 were combined with binary and ternary system data in constructing a quantitative model of the system. The simple combination of binary system results was not effective in predicting the observed ternary system behavior. In both terna...

Trace metal concentrations in the sediments and plants of the danube delta, romania

Abstract: Wetlands systems generally are considered as filters, retaining allochthonous metals that can have toxic effects on biota. We investigated patterns of spatial variability in trace metal concentrations in sediments and tissues ofPhragmites australis in the marshes of the Danube Delta, Romania in 1993 and 1994. Mean concentrations (±s.e) of Ni, Cr, and Pb in roots were 10.0±0.7, 2.7±0.2, and 11.3±0.5 μg g−1 dry wt, respectively, and in leaves were 0.3 ± 0.1, 0.1 ±0.0, 0.2 ± 0.0 μg g−1 dry wt, respectively. Mean concentrations (± s.e.) of Ni, Cr, Zn, and Cu extracted (0.5M HCl) from sediments were 16.4 ± 0.8, 3.0 ± 0.2, 45.4 ± 1.7, and 29.2 ± 2.3 μg g−1 dry wt, respectively. Sediment metal concentrations decreased significantly (p < 0.01) with distance from the Delta origin, but concentrations in roots and sediments did not vary with distance into the marsh from lake edges nor with distance from main river channels in the Delta. Concentrations of extractable metals from marsh sediments were not correlated to concentrations in roots, suggesting that factors other than labile concentrations in sediments control metal uptake and storage in roots.

Modeling the transport and reaction of trace metals in water‐saturated soils and sediments

Abstract: A model has been formulated of the equilibrium speciation, kinetic reaction, and transport of trace metals in the presence of biodegradation of organic substrates in saturated porous media. Kinetics of various processes (biodegradation, chemical reactions, and precipitation and dissolution of minerals) together with transport processes (advection, bioturbation, and diffusive/dispersive mixing) are quantified in a set of coupled mass balance equations (for the organic substrate, electron acceptors, reduced species, and trace metals). These steady state, one-dimensional equations are discretized using a second-order-accurate finite difference approximation. A pE is estimated at each node in the domain on the basis the concentrations calculated and the half reaction for the dominant terminal electron acceptor at that location. The dynamic model is coupled iteratively to a modified version of the U.S. Environmental Protection Agency's MINTEQA2, which calculates equilibrium chemical speciation (including aqueous speciation, adsorption, and precipitation of minerals) at each node of the domain. The primary dependent variables are the total dissolved concentrations of the aqueous species together with the solid concentrations of the minerals. To demonstrate that this formulation can simulate biodegradation using reaction rates consistent with published values, simulations are compared to data from the sediment pore waters of a small lake. Simulations are presented of the transport and reaction of arsenic in lake sediments to illustrate how this model can be used to evaluate trends in trace metal mobility as affected by various water quality parameters through their influence on the biogeochemistry of natural systems.

Trace Metal Speciation in Three Unbuffered Salt Solutions Used to Assess their Bioavailability in Soil

Abstract: Three unbuffered salt solutions used to estimate soil trace metal bioavailability were compared. The objective was to evaluate chemical speciation of Cd, Cu, Pb, and Zn in 0.01 M CaC l2 0.1 M NaNO 3 , and 1 M NH 4 NO 3 extracts. The metal in each extract were speciated with a model that was optimized experimentally using an exchange resin. In NH 4 NO 3 , Cd, Cu, and Zn were completely complexed by NH 3 . In extracts of pH lower than 6.5, Pb was essentially present as free Pb 2+ and metal-organic complexes. In extracts of higher pH, PbCO 3 and free Pb 2+ were dominant. In CaCl 2 , Cu and Zn were mainly present as organic complexes and free Zn 2+ , respectively. In all extracts, 50% of Cd was free Cd 2+ and 50% CdCl + . As pH increased, the proportions of free Pb 2+ and organic complexes decreased while those of inorganic complexes increased. In NaNO 3 , Cd, Cu, and Zn were, respectively, mainly present as free Cd 2+ , organic complexes and free Zn 2+ . Speciation of Pb changed with pH as in NH 4 NO 3 , Similarities were expected between the qualitative composition of the extracts and the soil solution, justifying the use of unbuffered salt solutions, particularly NaNO 3 and CaCl 2 , in the evaluation of soil trace metal availability.

Assessment of sediment toxicity and chemical concentrations in the San Diego Bay region, California, USA

Abstract: Sediment quality within San Diego Bay, Mission Bay, and the Tijuana River Estuary of California was investigated as part of an ongoing statewide monitoring effort (Bay Protection and Toxic Cleanup Program). Study objectives were to determine the incidence, spatial patterns, and spatial extent of toxicity in sediments and porewater; the concentration and distribution of potentially toxic anthropogenic chemicals; and the relationships between toxicity and chemical concentrations. Rhepoxynius abronius survival bioassays, grain size, and total organic carbon analyses were performed on 350 sediment samples. Strongylocentrotus purpuratus development bioassays were performed on 164 pore-water samples. Toxicity was demonstrated throughout the San Diego Bay region, with increased incidence and concordance occurring in areas of industrial and shipping activity. Trace metal and trace synthetic organic analyses were performed on 229 samples. Copper, zinc, mercury, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and chlordane were found to exceed ERM (effects range median) or PEL (probable effects level) sediment quality guidelines and were considered the six major chemicals or chemical groups of concern. Statistical analysis of the relationships between amphipod toxicity, bulk phase sediment chemistry, and physical parameters demonstrated few significant linear relationships. Significant differences in chemical levels were found between toxic and nontoxic responses using multivariate andmore » univariate statistics. Potential sources of anthropogenic chemicals were discussed.« less

Refining and Testing a Trace Metal Biomonitor (Chaoborus) in Highly Acidic Lakes

Abstract: Biomonitor organisms can be used to estimate bioavailable contaminant concentrations provided that a reliable model exists between organism and environmental contaminant concentrations. We evaluate...

Predicting the toxicity of sediment-associated trace metals with simultaneously extracted trace metal: Acid-volatile sulfide concentrations and dry weight-normalized concentrations: A critical comparison

Abstract: The relative abilities of sediment concentrations of simultaneously extracted trace metal: acid-volatile sulfide (SEM: AVS) and dry weight-normalized trace metals to correctly predict both toxicity and nontoxicity were compared by analysis of 77 field-collected samples. Relative to the SEM:AVS concentrations, sediment guidelines based upon dry weight-normalized concentrations were equally or slightly more accurate in predicting both nontoxic and toxic results in laboratory tests.

Heavy metals in soils of Argentina: Comparison between urban and agricultural soils

Abstract: Trace metals, including heavy metals, can be harmful to the biota and human beings. This leads to study the accumulation of those elements in soils. In the Pampean region (Argentina) this knowledge is scarce. Our objectives were to (i) determine the trace metal concentration in soils of Buenos Aires City and agricultural areas, (ii) start to establish the soil trace metals baseline concentration, and (iii) find relationships between soil properties and those elements Topsoil samples were taken in Buenos Aires City and on farms along an arc 50 to 250 km away from the metropolis. All studied soils were Mollisols. Soil samples were analyzed for their cadmium (Cd), copper (Cu), zinc (Zn), chromium (Cr), cobalt (Co), lead (Pb), and nickel (Ni) contents by acid extraction. Soil properties were determined using standard methods. The soils of Buenos Aires City show the highest average concentrations of Cd, Cu, Pb, and Zn. The further the sampling sites were from Buenos Aires, the lower the metal concentr...

The aquatic insect Chaoborus as a biomonitor of trace metals in lakes

Abstract: We tested larvae of three species of the widespread lacustrine insect Chaoborus as potential biomonitors of the trace metals Cd, Cu, Pb, and Zn. Chemical and biological measurements were made in a large number of lakes covering a wide range of pHs and trace metal concentrations and distributed over a large geographical area. Concentrations of Cu and Zn in sediment and water varied widely among lakes but not in animals, suggesting that the insects regulate these essential metals over a wide range of environmental concentrations and consequently would be of little use for monitoring Cu or Zn. Although lead concentrations in the Chaoborus species varied more widely than did those of Cu or Zn, we were not able to relate larval Pb concentrations consistently to those! in sediment or water, suggesting that further research on this metal is needed. Cadmium concentrations in Chaoborus were not well explained by total Cd concentrations in either sediment or water. We found that Cd concentrations in animals were better predicted by free Cd ion concentrations provided that we took into account competition between hydrogen ions and free cadmium ions at biological uptake sites. This result is consistent with the mainly laboratory based free-sion activity model and suggests that this model would provide an effective theoretical framework for the use of Chaoborus larvae as Cd biomonitors in nature.