Multi-scale analysis of the occurrence of Pb, Cr and Mn in the NIST standards: Urban dust (SRM 1649a) and indoor dust (SRM 2584)

NASA Astrophysics Data System (ADS)

Jiang, Mingyu; Nakamatsu, Yuki; Jensen, Keld A.; Utsunomiya, Satoshi

2014-01-01

Adverse health effects of ambient particulate matters are closely related to the speciation of the constituting organic matters and toxic metals. To determine multi-parameters of the metal speciation in urban and indoor dusts, we have performed systematic bulk- to nano-scale (“multi-scale”) analysis on the speciation of Pb, Mn, and Cr in two National Institute of Standards and Technology (NIST) standard reference materials (SRMs): urban dust (SRM 1649a) and indoor dust (SRM 2584), utilizing X-ray absorption near-edge structure, powder X-ray diffraction analysis, electron microprobe analysis, scanning electron microscopy, and transmission electron microscopy. Major crystalline phases are quartz, gypsum, kaolinite, and muscovite in SRM 1649a, while quartz, gypsum, calcite, and possibly muscovite (or chabazite) in SRM 2584. A number of Pb sulfate nanoparticles (50-200 nm) occur in SRM 1649a, whereas micron-sized Pb carbonate is present containing various concentrations of Zn and Ti in the complex texture in SRM 2584. Relatively soluble Mn(II) sulfate is the bulk-averaged Mn speciation in SRM 1649a, although discrete Mn sulfate particles are not characterized by individual particle analysis, implying the diluted Mn distribution within other sulfate. In SRM 2584, Mn speciation includes a mixture of oxides and carbonates, and trace Mn in chromite. Chromite (FeCr2O4) is the major Cr speciation in SRM1694a, while unidentified Cr(III) phases with minor chromite and Pb chromate are present in SRM 2584, among which the Pb chromate is composed of Cr(VI). A significant number of the metal-bearing particles are distributed to the submicron-size fraction in the urban dust, SRM 1649a, suggesting that these metal nanoparticles can potentially penetrate into the deep respiratory system. This study demonstrates that multi-scale analysis combining nano and bulk analytical techniques is a powerful approach to investigate the multi-parameters of metal-bearing nanoparticles in heterogeneous PM samples.

Nanometer-sized materials for solid-phase extraction of trace elements.

PubMed

Hu, Bin; He, Man; Chen, Beibei

2015-04-01

This review presents a comprehensive update on the state-of-the-art of nanometer-sized materials in solid-phase extraction (SPE) of trace elements followed by atomic-spectrometry detection. Zero-dimensional nanomaterials (fullerene), one-dimensional nanomaterials (carbon nanotubes, inorganic nanotubes, and nanowires), two-dimensional nanomaterials (nanofibers), and three-dimensional nanomaterials (nanoparticles, mesoporous nanoparticles, magnetic nanoparticles, and dendrimers) for SPE are discussed, with their application for trace-element analysis and their speciation in different matrices. A variety of other novel SPE sorbents, including restricted-access sorbents, ion-imprinted polymers, and metal-organic frameworks, are also discussed, although their applications in trace-element analysis are relatively scarce so far.

Cellular processing of gold nanoparticles: CE-ICP-MS evidence for the speciation changes in human cytosol.

PubMed

Legat, Joanna; Matczuk, Magdalena; Timerbaev, Andrei R; Jarosz, Maciej

2018-01-01

The cellular uptake of gold nanoparticles (AuNPs) may (or may not) affect their speciation, but information on the chemical forms in which the particles exist in the cell remains obscure. An analytical method based on the use of capillary electrophoresis hyphenated with inductively coupled plasma mass spectrometry (ICP-MS) has been proposed to shed light on the intracellular processing of AuNPs. It was observed that when being introduced into normal cytosol, the conjugates of 10-50 nm AuNPs with albumin evolved in human serum stayed intact. On the contrary, under simulated cancer cytosol conditions, the nanoconjugates underwent decomposition, the rate of which and the resulting metal speciation patterns were strongly influenced by particle size. The new peaks that appeared in ICP-MS electropherograms could be ascribed to nanosized species, as upon ultracentrifugation, they quantitatively precipitated whereas the supernatant showed only trace Au signals. Our present study is the first step to unravel a mystery of the cellular chemistry for metal-based nanomedicines.

Sulfidization of Organic Freshwater Flocs from a Minerotrophic Peatland: Speciation Changes of Iron, Sulfur, and Arsenic.

PubMed

ThomasArrigo, Laurel K; Mikutta, Christian; Lohmayer, Regina; Planer-Friedrich, Britta; Kretzschmar, Ruben

2016-04-05

Iron-rich organic flocs are frequently observed in surface waters of wetlands and show a high affinity for trace metal(loid)s. Under low-flow stream conditions, flocs may settle, become buried, and eventually be subjected to reducing conditions facilitating trace metal(loid) release. In this study, we reacted freshwater flocs (704-1280 mg As/kg) from a minerotrophic peatland (Gola di Lago, Switzerland) with sulfide (5.2 mM, S(-II)spike/Fe = 0.75-1.62 mol/mol) at neutral pH and studied the speciation changes of Fe, S, and As at 25 ± 1 °C over 1 week through a combination of synchrotron X-ray techniques and wet-chemical analyses. Sulfidization of floc ferrihydrite and nanocrystalline lepidocrocite caused the rapid formation of mackinawite (52-81% of Fesolid at day 7) as well as solid-phase associated S(0) and polysulfides. Ferrihydrite was preferentially reduced over lepidocrocite, although neoformation of lepidocrocite from ferrihydrite could not be excluded. Sulfide-reacted flocs contained primarily arsenate (47-72%) which preferentially adsorbed to Fe(III)-(oxyhydr)oxides, despite abundant mackinawite precipitation. At higher S(-II)spike/Fe molar ratios (≥1.0), the formation of an orpiment-like phase accounted for up to 35% of solid-phase As. Despite Fe and As sulfide precipitation and the presence of residual Fe(III)-(oxyhydr)oxides, mobilization of As was recorded in all samples (Asaq = 0.45-7.0 μM at 7 days). Aqueous As speciation analyses documented the formation of thioarsenates contributing up to 33% of Asaq. Our findings show that freshwater flocs from the Gola di Lago peatland may become a source of As under sulfate-reducing conditions and emphasize the pivotal role Fe-rich organic freshwater flocs play in trace metal(loid) cycling in S-rich wetlands characterized by oscillating redox conditions.

Micronutrient metal speciation is controlled by competitive organic chelation in grassland soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boiteau, Rene M.; Shaw, Jared B.; Pasa-Tolic, Ljiljana

Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or howmore » they interact and compete for metal binding. Identifying these metallo-organic species within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrix. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) from Kansas Prairie soil. Both plant and fungal chelators were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant iron acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamine, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2-57 pmol / g soil). In contrast, the fungal siderophore ferricrocine bound comparatively more trivalent Fe (9pmol / g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population. Even small structural differences result in significant differences in their environmental metal speciation, and likely impact metal uptake within the rhizosphere of calcareous soils.« less

Cloud iron speciation: Experimental simulations

NASA Astrophysics Data System (ADS)

Sofikitis, A. M.; Colin, J. L.; Desboeufs, K. V.; Losno, R.

2003-04-01

The aim of our contribution is to identify major processes controlling iron speciation in the atmospheric aqueous phase. Fe is known to participate in a variety of redox reactions in cloud chemistry, as well as controlling free radical production in the troposphere. Iron cycling is slower than cycles with other catalytic transition metals (Cu, Mn). The residence time of each iron species is around ten minutes, this allows analytical separation and determination of each iron redox species and therefore its ratio. As the only source of trace metals in aqueous atmospheric phase is due to the solubilization of aerosols, we present here dissolution rate measurements obtained by laboratory experiments with an open flow reactor. This reactor enables us to reproduce the dissolution of a particle in aqueous atmospheric water. The dissolution rate and the speciation of iron are dependent on the mineralogy of the solid phase. Our experiments included Goethite, hematite and vermiculite, which are typical mineral constituents of dust particles. Comparisons were made with natural loess which is a blend of various crystalline and amorphous phases. We will present results of crustal origin particles dissolution experiments where kinetic parameters are determined, including iron speciation. Major functions of variation are pH and photochemistry in the aqueous weathering solution.

Distribution and speciation of trace elements in iron and manganese oxide cave deposits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Frierdich, Andrew J.; Catalano, Jeffrey G.

2012-10-24

Fe and Mn oxide minerals control the distribution and speciation of heavy metals and trace elements in soils and aquatic systems through chemical mechanisms involving adsorption, incorporation, and electron transfer. The Pautler Cave System in Southwest Illinois, an analog to other temperate carbonate-hosted karst systems, contains Fe and Mn oxide minerals that form in multiple depositional environments and have high concentrations of associated trace elements. Synchrotron-based micro-scanning X-ray fluorescence ({mu}-SXRF) shows unique spatial distributions of Fe, Mn, and trace elements in mineral samples. Profile maps of Mn oxide cave stream pebble coatings show Fe- and As-rich laminations, indicating dynamic redoxmore » conditions in the cave stream. {mu}-SXRF maps demonstrate that Ni, Cu, and Zn correlate primarily with Mn whereas As correlates with both Mn and Fe; As is more enriched in the Fe phase. Zn is concentrated in the periphery of Mn oxide stream pebble coatings, and may be an indication of recent anthropogenic surface activity. X-ray absorption fine structure spectroscopy measurements reveal that As(V) occurs as surface complexes on Mn and Fe oxides whereas Zn(II) associated with Mn oxides is adsorbed to the basal planes of phyllomanganates in a tetrahedral coordination. Co(III) and Se(IV) are also observed to be associated with Mn oxides. The observation of Fe, Mn, and trace element banding in Mn oxide cave stream pebble coatings suggests that these materials are sensitive to and document aqueous redox conditions, similar to ferromanganese nodules in soils and in marine and freshwater sediments. Furthermore, speciation and distribution measurements indicate that these minerals scavenge trace elements and limit the transport of micronutrients and contaminants in karst aquifer systems while also potentially recording changes in anthropogenic surface activity and land-use.« less

Identification of the typical metal particles among haze, fog, and clear episodes in the Beijing atmosphere.

PubMed

Hu, Yunjie; Lin, Jun; Zhang, Suanqin; Kong, Lingdong; Fu, Hongbo; Chen, Jianmin

2015-04-01

For a better understanding of metal particle morphology and behaviors in China, atmospheric aerosols were sampled in the summer of 2012 in Beijing. The single-particle analysis shows various metal-bearing speciations, dominated by oxides, sulfates and nitrates. A large fraction of particles is soluble. Sources of Fe-bearing particles are mainly steel industries and oil fuel combustion, whereas Zn- and Pb-bearing particles are primarily contributed by waste incineration, besides industrial combustion. Other trace metal particles play a minor rule, and may come from diverse origins. Mineral dust and anthropogenic source like vehicles and construction activities are of less importance to metal-rich particles. Statistics of 1173 analyzed particles show that Fe-rich particles (48.5%) dominate the metal particles, followed by Zn-rich particles (34.9%) and Pb-rich particles (15.6%). Compared with the abundances among clear, haze and fog conditions, a severe metal pollution is identified in haze and fog episodes. Particle composition and elemental correlation suggest that the haze episodes are affected by the biomass burning in the southern regions, and the fog episodes by the local emission with manifold particle speciation. Our results show the heterogeneous reaction accelerated in the fog and haze episodes indicated by more zinc nitrate or zinc sulfate instead of zinc oxide or carbonate. Such information is useful in improving our knowledge of fine airborne metal particles on their morphology, speciation, and solubility, all of which will help the government introduce certain control to alleviate metal pollution. Copyright © 2014 Elsevier B.V. All rights reserved.

Emissions inventory of PM2.5 trace elements across the United States

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adam Reff; Prakash V. Bhave; Heather Simon

2009-08-15

This paper presents the first National Emissions Inventory (NEI) of fine particulate matter (PM2.5) that includes the full suite of PM2.5 trace elements (atomic number >10) measured at ambient monitoring sites across the U.S. PM2.5 emissions in the NEI were organized and aggregated into a set of 84 source categories for which chemical speciation profiles are available (e.g., Unpaved Road Dust, Agricultural Soil, Wildfires). Emission estimates for ten metals classified as Hazardous Air Pollutants (HAP) were refined using data from a recent HAP NEI. All emissions were spatially gridded, and U.S. emissions maps for dozens of trace elements (e.g., Fe,more » Ti) are presented for the first time. Nationally, the trace elements emitted in the highest quantities are silicon (3.8 x 10{sup 5} ton/yr), aluminium (1.4 x 10{sup 5} ton/yr), and calcium (1.3 x 10{sup 5} ton/yr). Our chemical characterization of the PM2.5 inventory shows that most of the previously unspeciated emissions are comprised of crustal elements, potassium, sodium, chlorine, and metal-bound oxygen. Coal combustion is the largest source of S, Se, Sr, Hg and primary sulfates. This work also reveals that the largest PM2.5 sources lacking specific speciation data are off-road diesel-powered mobile equipment, road construction dust, marine vessels, gasoline-powered boats, and railroad locomotives. 28 refs., 4 figs.« less

Electrochemical sensors and devices for heavy metals assay in water: the French groups' contribution

PubMed Central

Pujol, Luca; Evrard, David; Groenen-Serrano, Karine; Freyssinier, Mathilde; Ruffien-Cizsak, Audrey; Gros, Pierre

2014-01-01

A great challenge in the area of heavy metal trace detection is the development of electrochemical techniques and devices which are user-friendly, robust, selective, with low detection limits and allowing fast analyses. This review presents the major contribution of the French scientific academic community in the field of electrochemical sensors and electroanalytical methods within the last 20 years. From the well-known polarography to the up-to-date generation of functionalized interfaces, the different strategies dedicated to analytical performances improvement are exposed: stripping voltammetry, solid mercury-free electrode, ion selective sensor, carbon based materials, chemically modified electrodes, nano-structured surfaces. The paper particularly emphasizes their advantages and limits face to the last Water Frame Directive devoted to the Environmental Quality Standards for heavy metals. Recent trends on trace metal speciation as well as on automatic “on line” monitoring devices are also evoked. PMID:24818124

Diagnostic modeling of trace metal partitioning in south San Francisco Bay

USGS Publications Warehouse

Wood, T. W.; Baptista, A. M.; Kuwabara, J.S.; Flegal, A.R.

1995-01-01

The numerical results indicate that aqueous speciation will control basin-scale spatial variations in the apparent distribution coefficient, Kda, if the system is close to equilibrium. However, basin-scale spatial variations in Kda are determined by the location of the sources of metal and the suspended solids concentration of the receiving water if the system is far from equilibrium. The overall spatial variability in Kda also increases as the system moves away from equilibrium.

Culturing Selenastrum capricornutum (Chlorophyta) in a synthetic algal nutrient medium with defined mineral particulates

USGS Publications Warehouse

Kuwabara, J.S.; Davis, J.A.; Chang, Cecily C.Y.

1985-01-01

Algal nutrient studies in chemically-defined media typically employ a synthetic chelator to prevent iron hydroxide precipitation. Micronutrient-particulate interactions may, however, significantly affect chemical speciation and hence biovailability of these nutrients in natural waters. A technique is described by which Selenastrum capricornutum Printz (Chlorophyta) may be cultured in a medium where trace metal speciation (except iron) is controlled, not by organic chelation, but by sorption onto titanium dioxide. Application of this culturing protocol in conjunction with results from sorption studies of nutrient ions on mineral particles provides a means of studying biological impacts of sorptive processes in aquatic environments. ?? 1985 Dr W. Junk Publishers.

Spatial dependence of reduced sulfur in Everglades dissolved organic matter controlled by sulfate enrichment

USGS Publications Warehouse

Poulin, Brett A.; Ryan, Joseph N.; Nagy, Kathryn L.; Stubbins, Aron; Dittmar, Thorsten; Orem, William H.; Krabbenhoft, David P.; Aiken, George R.

2017-01-01

Sulfate inputs to the Florida Everglades stimulate sulfidic conditions in freshwater wetland sediments that affect ecological and biogeochemical processes. An unexplored implication of sulfate enrichment is alteration of the content and speciation of sulfur in dissolved organic matter (DOM), which influences the reactivity of DOM with trace metals. Here, we describe the vertical and lateral spatial dependence of sulfur chemistry in the hydrophobic organic acid fraction of DOM from unimpacted and sulfate-impacted Everglades wetlands using X-ray absorption spectroscopy and ultrahigh-resolution mass spectrometry. Spatial variation in DOM sulfur content and speciation reflects the degree of sulfate enrichment and resulting sulfide concentrations in sediment pore waters. Sulfur is incorporated into DOM predominantly as highly reduced species in sulfidic pore waters. Sulfur-enriched DOM in sediment pore waters exchanges with overlying surface waters and the sulfur likely undergoes oxidative transformations in the water column. Across all wetland sites and depths, the total sulfur content of DOM correlated with the relative abundance of highly reduced sulfur functionality. The results identify sulfate input as a primary determinant on DOM sulfur chemistry to be considered in the context of wetland restoration and sulfur and trace metal cycling.

Precise spectroscopic analysis of solar-type stars with moderate and fast rotation

NASA Astrophysics Data System (ADS)

Tsantaki, Maria

In the present work the performance and applicability of the thin mercury film electrode (TMFE) in the dynamic speciation of trace metals was investigated. Two different electroanalytical stripping techniques were used: the classical anodic stripping voltammetry (ASV) and a recent developed technique, scanning stripping chronopotentiometry (SSCP). The ion-exchange and the mass transport features of novel mixed coatings of two sulfonated cation-exchange polymers with dissimilar characteristics, Nafion (NA) and poly(sodium 4-styrenesulfonate) (PSS) were evaluated, prior to its application in the field of trace metal analysis. Suitable NA-PSS polymer coatings could be used in the modification of TMFE, presenting a high sensitivity, reproducibility, mechanical stability and adequate antifouling properties in the ASV determination of trace metal cations in complex media. Also the features of the PSS polyelectrolyte layers for ion-exchange voltammetry (IEV) were evaluated. The goal was to search for the best conditions to obtain stable PSS coated electrodes, which could present high negative charge densities in order to enhance the electrostatic accumulation of cations within the film, thus enlarging the ASV signal. The applicability and performance of the TMFE in the trace metal speciation studies, by SSCP, were for the first time exploited. The optimized TMFE presented a high sensitivity and resolution, being an excellent complement to the conventional mercury electrodes and could be use for 1-day term with no significant variation in the SCP analytical signal and no apparent degradation. The calculated SSCP curves were in excellent agreement with experimental data at the TMFE and the stability constant (K), calculated from the shift in the SSCP half-wave potential, of two labile metal-complex systems were in good agreement with the ones obtained using the conventional Hanging mercury drop electrode (HMDE) and those predicted by theory. Additionally, the experimental lability diagnosis inherent to the SSCP technique was validated and a rigorous quantification of the lability degree was made. Due to the well defined hydrodynamic conditions at the thin mercury film rotating disk electrode (TMF-RDE), during the deposition step, this electrode is quite valuable in the determination of kinetic parameters, like the association rate constants (ka).

Experimental and Theoretical Approaches for the Surface Interaction between Copper and Activated Sludge Microorganisms at Molecular Scale

NASA Astrophysics Data System (ADS)

Luo, Hong-Wei; Chen, Jie-Jie; Sheng, Guo-Ping; Su, Ji-Hu; Wei, Shi-Qiang; Yu, Han-Qing

2014-11-01

Interactions between metals and activated sludge microorganisms substantially affect the speciation, immobilization, transport, and bioavailability of trace heavy metals in biological wastewater treatment plants. In this study, the interaction of Cu(II), a typical heavy metal, onto activated sludge microorganisms was studied in-depth using a multi-technique approach. The complexing structure of Cu(II) on microbial surface was revealed by X-ray absorption fine structure (XAFS) and electron paramagnetic resonance (EPR) analysis. EPR spectra indicated that Cu(II) was held in inner-sphere surface complexes of octahedral coordination with tetragonal distortion of axial elongation. XAFS analysis further suggested that the surface complexation between Cu(II) and microbial cells was the distorted inner-sphere coordinated octahedra containing four short equatorial bonds and two elongated axial bonds. To further validate the results obtained from the XAFS and EPR analysis, density functional theory calculations were carried out to explore the structural geometry of the Cu complexes. These results are useful to better understand the speciation, immobilization, transport, and bioavailability of metals in biological wastewater treatment plants.

Combining cross flow ultrafiltration and diffusion gradients in thin-films approaches to determine trace metal speciation in freshwaters

NASA Astrophysics Data System (ADS)

Liu, Ruixia; Lead, Jamie R.; Zhang, Hao

2013-05-01

Cross flow ultrafiltration (CFUF) and diffusive gradients in thin films (DGT) with open pore gel (OP) and restricted pore gel (RP) were used to measure trace metal speciation in selected UK freshwaters. The proportions of metals present in particulate forms (>1 μm) varied widely between 40-85% Pb, 60-80% Al, 7-56% Mn, 10-49% Cu, 0-55% Zn, 20-38% Cr, 20-30% Fe, 6-25% Co, 5-22% Cd and <7% Ni. In the colloidal fraction (2 kDa-1 μm) values varied between 53-91% Pb, 33-55% Al, 21-55% Cu, 20-44% Fe, 34-36% Cr, 20-40% Cd, 7-28% Co and Ni, 2-32% Zn and <8% Mn. Wide variations were also observed in the ultrafiltered fraction (<2 kDa). These results indicated that colloids indeed influenced the occurrence and transport of Al, Fe, Cr, Co, Ni, Cu, Zn, Cr and Pb metals in rivers, while inorganic or organic colloids did not exert an important control on Mn transport in the selected freshwaters. Of total species, total labile metal measured by DGT-OP accounted for 1.4-50% for Al, Fe, Co, Ni, Cu, Cd and Pb in all selected waters. Of these metals total labile Pb concentration was the lowest with value less than 1.4% although this value slightly increased after deducting particulate fractions. In some waters, a majority of total Mn, Zn and Cr is DGT labile, in which the DGT labile Mn fraction accounted for 98-118% of the total dissolved phase. In most cases, the inorganic labile concentration measured by DGT-RP was lower than the total labile metal concentration. By the combination of CFUF and DGT techniques, the concentrations of total labile and inorganic labile metal species in CFUF-derived truly dissolved phase were measured in four water samples. 100% of ultrafiltered Mn species was found to be total DGT labile. The proportions of total labile metal species were lower than those of ultrafiltered fraction for Al, Fe, Co, Ni, Cu, Cd and Pb in all selected waters, and Cr and Zn in some cases, indicating a large amount of natural complexing ligands with smaller size for the metals to form kinetically inert species or thermodynamically stable complexes. Observed discrepancies in metal speciation between metals and within sampling sites were related to the differences in the characteristics of the metals and the nature of water sources.

Past and Present Weathering Recorded in Cretaceous Shale Samples from Colombia - Implications for Paleoenvironmental Reconstructions

NASA Astrophysics Data System (ADS)

Mahoney, C.; März, C.; Wagner, T.

2016-12-01

It is well known that for geochemical studies on ancient rocks, outcrop samples can be compromised by present-day weathering. This raises the fundamental question, if only outcrop samples are available, how reliable can paleoenvironmental reconstructions be? To answer this question, shale samples have been gathered from Cretaceous outcrops of the Eastern Cordillera of Colombia, and analysed by XRF and Fe speciation in order to investigate paleo-redox conditions in this margin basin of the Proto-Atlantic. The samples are consistently depleted (relative to average shale) in redox-related trace metals and in total Fe indicating oxic conditions, whereas Fe speciation (highly reactive over total Fe) indicates anoxic conditions. We ask if this depletion in trace metals and total Fe is due to a lack of primary supply from the depositional environment, or if is it caused by modern oxidative outcrop weathering in this tropical mountainous setting? Our results from artificial weathering experiments confirm that certain trace metals U, Zn and Mo are easily leached from the samples, whereas Fe is quantitatively retained in the samples due to conversion of pyrite and siderite to Fe oxides. Pristine samples from wells in the adjacent Middle Magdalena Valley Basin (MMV) also exhibit total Fe depletion, but are up to 2000-fold enriched in Mo. This combined evidence indicates that the depletion of trace metals may be due to contemporary weathering, but there has to be a paleoenvironmental reason behind the low total Fe signature. The Guiana Shield was the probable source of sediment to the Cretaceous basin. The Chemical Index of Alteration suggest the source of detrital material was initially highly weathered (average 83, maximum 95). Ancient laterites have been identified on the Guiana Shield, and retention of Fe in these laterites may explain the low Fe input into the Eastern Cordillera basin. These results confirm that trace metal-based redox proxies may be seriously affected by oxidative weathering in outcrops, and caution should be applied when using such samples. But it also appears that due to the extreme chemical weathering in the provenance area, the Eastern Cordillera basin (and adjacent MMV basin) was unusually Fe-depleted throughout the Cretaceous, and this geochemical signal is preserved even in weathered outcrop samples.

Micronutrient metal speciation is driven by competitive organic chelation in grassland soils.

NASA Astrophysics Data System (ADS)

Boiteau, R.; Shaw, J. B.; Paša-Tolić, L.; Koppenaal, D.; Jansson, J.

2017-12-01

Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or how they interact and compete for metal binding. Identifying these metallo-organic species within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrix. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) from Kansas Prairie soil. Both plant and fungal chelators were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant iron acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamine, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2-57 pmol / g soil). In contrast, the fungal siderophore ferricrocine bound comparatively more trivalent Fe (9pmol / g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population.

Preservation of NOM-metal complexes in a modern hyperalkaline stalagmite: Implications for speleothem trace element geochemistry

NASA Astrophysics Data System (ADS)

Hartland, Adam; Fairchild, Ian J.; Müller, Wolfgang; Dominguez-Villar, David

2014-03-01

We report the first quantitative study of the capture of colloidal natural organic matter (NOM) and NOM-complexed trace metals (V, Co, Cu, Ni) in speleothems. This study combines published NOM-metal dripwater speciation measurements with high-resolution laser ablation ICPMS (LA-ICPMS) and sub-annual stable isotope ratio (δ18O and δ13C), fluorescence and total organic carbon (TOC) analyses of a fast-growing hyperalkaline stalagmite (pH ˜11) from Poole’s Cavern, Derbyshire UK, which formed between 1997 and 2008 AD. We suggest that the findings reported here elucidate trace element variations arising from colloidal transport and calcite precipitation rate changes observed in multiple, natural speleothems deposited at ca. pH 7-8. We find that NOM-metal(aq) complexes on the boundary between colloidal and dissolved (˜1 nm diameter) show an annual cyclicity which is inversely correlated with the alkaline earth metals and is explained by calcite precipitation rate changes (as recorded by kinetically-fractionated stable isotopes). This relates to the strength of the NOM-metal complexation reaction, resulting in very strongly bound metals (Co in this system) essentially recording NOM co-precipitation (ternary complexation). More specifically, empirical partition coefficient (Kd) values between surface-reactive metals (V, Co, Cu, Ni) [expressed as ratio of trace element to Ca ratios in calcite and in solution] arise from variations in the ‘free’ fraction of total metal in aqueous solution (fm). Hence, differences in the preservation of each metal in calcite can be explained quantitatively by their complexation behaviour with aqueous NOM. Differences between inorganic Kd values and field measurements for metal partitioning into calcite occur where [free metal] ≪ [total metal] due to complexation reactions between metals and organic ligands (and potentially inorganic colloids). It follows that where fm ≈ 0, apparent inorganic Kd app values are also ≈0, but the true partition coefficient (Kd actual) is significantly higher. Importantly, the Kd of NOM-metal complexes [organic carbon-metal ratio) approaches 1 for the most stable aqueous complexes, as is shown here for Co, but has values of 24-150 for V, Ni and Cu. This implies that ternary surface complexation (metal-ligand co-adsorption) can occur (as for NOM-Co), but is the exception rather than the rule. We also demonstrate the potential for trace metals to record information on NOM composition as expressed through changing NOM-metal complexation patterns in dripwaters. Therefore, a suite of trace metals in stalagmites show variations clearly attributable to changes in organic ligand concentration and composition, and which potentially reflect the state of overlying surface ecosystems. The heterogeneous speciation and size distribution of aqueous NOM and metals (Lead and Wilkinson, 2006; Aiken et al., 2011). The variability in NOM-metal transport in caves that arises from the interaction between infiltration, flow routing, and the hydrodynamic properties of the fine colloids and particulates (Hartland et al., 2012). Variable dissociation kinetics through time as a function of (a) (Hartland et al., 2011). The surface charge of calcite and the availability of CaCO3 lattice sites as well as increased incidence of crystallographic defects with implications for incorporation of a range of trace species (Fairchild and Treble, 2009; Fairchild and Hartland, 2010). Thus, incorporation in speleothem calcite with consistent surface site properties will be determined by: The size and composition (i.e. hydrophilicity/hydrophobicity) of the NOM ligand, affecting adsorption and stability at the calcite surface. The lability (i.e. exchangeability) of the complexed metal and its binding affinity for the calcite surface. The concentration of aqueous complexes. Given the complexities, a partitioning approach to the problem is appropriate as a first approximation rather than a precise description. This study seeks to make the first quantitative connection between the organic and inorganic compositions of speleothems and thus determine the potential for speleothems to encode fluctuations in colloid-facilitated trace metal transport in karst aquifers. Recent findings of direct relevance to the present studyThe conjugate dripwater (PE1) to the stalagmite studied here (PC-08-1) was characterised in June 2009 using an array of complementary techniques, in which the size, speciation and lability of NOM-metal complexes was characterised (Hartland et al., 2011), where lability is defined as the capacity for complexes to dissociate in the context of the on-going interfacial process at the stalagmite surface. In PE1 dripwater, the most stable aqueous complexes were formed between Co and the finest, low molecular weight component of the NOM spectrum (Hartland et al., 2011). Speciation experiments demonstrated that Co was essentially non-exchangeable (free metal (fm) = <0.05), being retained in aqueous complexes, whilst Cu, Ni and V were all predominantly bound by NOM (fm = 0.2-0.3).In contrast, Sr and Ba were freely exchangeable between the solution and solid phase (Hartland et al., 2011) and Mg was absent, presumably due to the poor solubility of Mg(OH)2 at hyperalkaline pH (Ksp = 1.5 × 10-11): Mg2+(aq)+2OH-(aq)↔Mg( On the other hand, the transition metals were not lost as insoluble hydroxides (Hartland et al., 2012), despite having lower solubility than Mg (e.g. Cu(OH)2Ksp = 2.2 × 10-20); and this is consistent with the dominant role of NOM in solubilising and transporting the transition metals in this system (Hartland et al., 2011).The transport of metals by complexes with NOM in PE1 dripwater through the hydrological year was studied by Hartland et al. (2012). This study had two findings of direct relevance to the study of trace metal variations in the conjugate PC-08-1 stalagmite: Complexes between metals and the smallest, low-molecular weight fraction of NOM showed an attenuated delivery in dripwaters consistent with the non-conservative behaviour of analogous tracers in fractured-rock studies due to diffusion into micro-fractures. This mode of transport was termed ‘low-flux’ and was the dominant mode of transport for Co and V. Complexes between metals and coarse colloids (>100 nm) and particulates (>1000 nm) showed a rapid responsiveness to infiltration events. This was termed the ‘high-flux’ mode of NOM-metal transport and was interpreted as being dominantly fracture-fed. This mode of transport was dominated by Cu, Zn and Ni. The ‘high-flux’ vs ‘low-flux’ interplay of trace metal transport is summarised in Fig. 1.The PC-08-1 stalagmite studied here was deposited following the removal of stalagmite PC-97-1 studied by Baker et al. (1999b) and which grew under the PE1 drip point between 1927 and 1997. Both the PC-97-1 stalagmite and its regrowth (PC-08-1) are characterised by annual lamina couplets consisting of a porous pale layer and a dense fluorescent layer. Fluorescence in the PC-97-1 stalagmite displayed a marked sinusoidal pattern with 10% of laminae exhibiting a double band structure (Baker et al., 1999b).

Geochemical distribution, fractionation and contamination assessment of heavy metals in marine sediments of the Asaluyeh port, Persian Gulf.

PubMed

Delshab, Hossein; Farshchi, Parvin; Keshavarzi, Behnam

2017-02-15

In this study, total concentration and speciation of heavy metals in sediments of the Asaluyeh, one of the Iran's largest commercial ports, are investigated. 48 sediment samples were collected and analyzed for trace and major elements. Sediment quality guidelines along with calculated enrichment factors and trace metal profiles indicate that Asaluyeh port is threated by contamination, especially with respect to Hg and Cu. Normalization to Sc indicated high enrichment factors in the sediments following the decreasing order of: Hg>Cu>As>Ni>Zn>Pb≈Cr≈Mn>Co≈V≈Fe≈Al. Hg displayed the greatest potential ecological risk factor among sampling stations. The results of sequential extraction procedure revealed that in some stations >50% of Mn, V, Cu and Zn occur in potentially mobile phases and therefore are more readily mobilized in the sediments of the study area. Copyright © 2016 Elsevier Ltd. All rights reserved.

Quantification of trace elements and speciation of iron in atmospheric particulate matter

NASA Astrophysics Data System (ADS)

Upadhyay, Nabin

Trace metal species play important roles in atmospheric redox processes and in the generation of oxidants in cloud systems. The chemical impact of these elements on atmospheric and cloud chemistry is dependent on their occurrence, solubility and speciation. First, analytical protocols have been developed to determine trace elements in particulate matter samples collected for carbonaceous analysis. The validated novel protocols were applied to the determination of trace elements in particulate samples collected in the remote marine atmosphere and urban areas in Arizona to study air pollution issues. The second part of this work investigates on solubility and speciation in environmental samples. A detailed study on the impact of the nature and strength of buffer solutions on solubility and speciation of iron lead to a robust protocol, allowing for comparative measurements in matrices representative of cloud water conditions. Application of this protocol to samples from different environments showed low iron solubility (less than 1%) in dust-impacted events and higher solubility (5%) in anthropogenically impacted urban samples. In most cases, Fe(II) was the dominant oxidation state in the soluble fraction of iron. The analytical protocol was then applied to investigate iron processing by fogs. Field observations showed that only a small fraction (1%) of iron was scavenged by fog droplets for which each of the soluble and insoluble fraction were similar. A coarse time resolution limited detailed insights into redox cycling within fog system. Overall results suggested that the major iron species in the droplets was Fe(1I) (80% of soluble iron). Finally, the occurrence and sources of emerging organic pollutants in the urban atmosphere were investigated. Synthetic musk species are ubiquitous in the urban environment (less than 5 ng m-3) and investigations at wastewater treatment plants showed that wastewater aeration basins emit a substantial amount of these species to the atmosphere.

Dissolved and labile concentrations of Cd, Cu, Pb, and Zn in the South Fork Coeur d'Alene River, Idaho: Comparisons among chemical equilibrium models and implications for biotic ligand models

USGS Publications Warehouse

Balistrieri, L.S.; Blank, R.G.

2008-01-01

In order to evaluate thermodynamic speciation calculations inherent in biotic ligand models, the speciation of dissolved Cd, Cu, Pb, and Zn in aquatic systems influenced by historical mining activities is examined using equilibrium computer models and the diffusive gradients in thin films (DGT) technique. Several metal/organic-matter complexation models, including WHAM VI, NICA-Donnan, and Stockholm Humic model (SHM), are used in combination with inorganic speciation models to calculate the thermodynamic speciation of dissolved metals and concentrations of metal associated with biotic ligands (e.g., fish gills). Maximum dynamic metal concentrations, determined from total dissolved metal concentrations and thermodynamic speciation calculations, are compared with labile metal concentrations measured by DGT to assess which metal/organic-matter complexation model best describes metal speciation and, thereby, biotic ligand speciation, in the studied systems. Results indicate that the choice of model that defines metal/organic-matter interactions does not affect calculated concentrations of Cd and Zn associated with biotic ligands for geochemical conditions in the study area, whereas concentrations of Cu and Pb associated with biotic ligands depend on whether the speciation calculations use WHAM VI, NICA-Donnan, or SHM. Agreement between labile metal concentrations and dynamic metal concentrations occurs when WHAM VI is used to calculate Cu speciation and SHM is used to calculate Pb speciation. Additional work in systems that contain wide ranges in concentrations of multiple metals should incorporate analytical speciation methods, such as DGT, to constrain the speciation component of biotic ligand models. ?? 2008 Elsevier Ltd.

Speciations of trace metals in the Danube alluvial sediments within an oil refinery.

PubMed

Relić, Dubravka; Dordević, Dragana; Popović, Aleksandar; Blagojević, Tamara

2005-07-01

A sequential extraction procedure was applied to identify forms of Ni, Zn, Pb and Cu with Fe- and Mn-oxides associated in alluvial sediments of the River Danube within Pancevo Oil Refinery (Serbia). The five steps of the sequential extraction procedure partitioned metals into: CH(3)COONH(4) extractable (S1); NH(2)OH.HCl carbonate extractable and easily reducible (S2); (NH(4))(2)C(2)O(2)/H(2)C(2)O(2) moderately reducible (S3); H(2)O(2)-HNO(3) organic extractable (S4); and HCl acid soluble residue (S5). Extracted concentrations of trace metals, analyzed after all five steps, were found to be (mg kg(-1)) for Mn: 656, Fe: 26734, Ni: 32.3, Zn: 72.8, Pb: 13.4 and Cu: 27.0. Most of the elements were found in acid soluble residue, characterizing stable compounds in sediments. Non-residual fractions of trace metals (sum of the first four fractions) were analyzed because they are more bioavailable than the residual amount. Correlation analysis and two multivariate analysis methods (principal component and cluster analysis) were used to understand and visualize the associations between the non-residual fractions of trace metals and certain forms, more or less crystalline of Fe- and Mn-oxides within the analyzed sediments, since Fe- and Mn-oxides play an important role in trace metal sorption within aquatic systems, especially within the Danube alluvium where the fluctuations of groundwater are very frequent and the level of groundwater could come close to surface.

Geochemical, metagenomic and metaproteomic insights into trace metal utilization by methane-oxidizing microbial consortia in sulfidic marine sediments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glass, DR. Jennifer; Yu, DR. Hang; Steele, Joshua

Microbes have obligate requirements for trace metals in metalloenzymes that catalyze important biogeochemical reactions. In anoxic methane- and sulfide-rich environments, microbes may have unique adaptations for metal acquisition and utilization due to decreased bioavailability as a result of metal sulfide precipitation. However, micronutrient cycling is largely unexplored in cold ( 10 C) and sulfidic (>1 mM H2S) deep-sea methane seep ecosystems. We investigated trace metal geochemistry and microbial metal utilization in methane seeps offshore Oregon and California, USA, and report dissolved concentrations of nickel (0.5-270 nM), cobalt (0.5-6 nM), molybdenum (10-5,600 nM) and tungsten (0.3-8 nM) in Hydrate Ridge sedimentmore » porewaters. Despite low levels of cobalt and tungsten, metagenomic and metaproteomic data suggest that microbial consortia catalyzing anaerobic oxidation of methane utilize both scarce micronutrients in addition to nickel and molybdenum. Genetic machinery for cobalt-containing vitamin B12 biosynthesis was present in both anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB). Proteins affiliated with the tungsten-containing form of formylmethanofuran dehydrogenase were expressed in ANME from two seep ecosystems, the first evidence for expression of a tungstoenzyme in psychrotolerant microorganisms. Finally, our data suggest that chemical speciation of metals in highly sulfidic porewaters may exert a stronger influence on microbial bioavailability than total concentration« less

Visualizing speciation in artificial cichlid fish.

PubMed

Clement, Ross

2006-01-01

The Cichlid Speciation Project (CSP) is an ALife simulation system for investigating open problems in the speciation of African cichlid fish. The CSP can be used to perform a wide range of experiments that show that speciation is a natural consequence of certain biological systems. A visualization system capable of extracting the history of speciation from low-level trace data and creating a phylogenetic tree has been implemented. Unlike previous approaches, this visualization system presents a concrete trace of speciation, rather than a summary of low-level information from which the viewer can make subjective decisions on how speciation progressed. The phylogenetic trees are a more objective visualization of speciation, and enable automated collection and summarization of the results of experiments. The visualization system is used to create a phylogenetic tree from an experiment that models sympatric speciation.

Trace gas and particle emissions from domestic and industrial biofuel use and garbage burning in central Mexico

Treesearch

T. J. Christian; R. J. Yokelson; B. Cardenas; L. T. Molina; G. Engling; S.-C. Hsu

2009-01-01

In central Mexico during the spring of 2007 we measured the initial emissions of 12 gases and the aerosol speciation for elemental and organic carbon (EC, OC), anhydrosugars, Cl-, NO-3 , and 20 metals from 10 cooking fires, four garbage fires, three brick making kilns, three charcoal making kilns, and two crop residue fires. Biofuel use has been estimated at over 2600...

Trace gas and particle emissions from domestic and industrial biofuel use and garbage burning in central Mexico

Treesearch

T. J. Christian; R. J. Yokelson; B. Cardenas; L. T. Molina; G. Engling; S.-C. Hsu

2010-01-01

In central Mexico during the spring of 2007 we measured the initial emissions of 12 gases and the aerosol speciation for elemental and organic carbon (EC, OC), anhydrosugars, Cl-, NO-3 , and 20 metals from 10 cooking fires, four garbage fires, three brick making kilns, three charcoal making kilns, and two crop residue fires. Global biofuel use has been...

Feedback Interactions between Trace Metal Nutrients and Phytoplankton in the Ocean

PubMed Central

Sunda, William G.

2012-01-01

In addition to control by major nutrient elements (nitrogen, phosphorus, and silicon) the productivity and species composition of marine phytoplankton communities are also regulated by a number of trace metal nutrients (iron, zinc, cobalt, manganese, copper, and cadmium). Of these, iron is most limiting to phytoplankton growth and has the greatest effect on algal species diversity. It also plays an important role in limiting di-nitrogen (N2) fixation rates, and thus is important in controlling ocean inventories of fixed nitrogen. Because of these effects, iron is thought to play a key role in regulating biological cycles of carbon and nitrogen in the ocean, including the biological transfer of carbon to the deep sea, the so-called biological CO2 pump, which helps regulate atmospheric CO2 and CO2-linked global warming. Other trace metal nutrients (zinc, cobalt, copper, and manganese) have lesser effects on productivity; but may exert an important influence on the species composition of algal communities because of large differences in metal requirements among species. The interactions between trace metals and ocean plankton are reciprocal: not only do the metals control the plankton, but the plankton regulate the distributions, chemical speciation, and cycling of these metals through cellular uptake and recycling processes, downward flux of biogenic particles, biological release of organic chelators, and mediation of redox reactions. This two way interaction has influenced not only the biology and chemistry of the modern ocean, but has had a profound influence on biogeochemistry of the ocean and earth system as a whole, and on the evolution of marine and terrestrial biology over geologic history. PMID:22701115

Micronutrient metal speciation is controlled by competitive organic chelation in grassland soils

DOE PAGES

Boiteau, Rene M.; Shaw, Jared B.; Pasa-Tolic, Ljiljana; ...

2018-03-08

Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or howmore » they interact and compete for metal binding. Identifying these metallophores within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrices. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) of soils from native tallgrass prairies in Kansas and Iowa. Both plant and fungal metallophores were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant Fe acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamines, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2–90 pmol/g soil). In contrast, the fungal siderophore ferricrocin was specific for trivalent Fe (7–32 pmol/g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population. In conclusion, small structural modifications result in significant differences in metal ligand selectivity, and likely impact metal uptake within the rhizosphere of grassland soils.« less

Micronutrient metal speciation is controlled by competitive organic chelation in grassland soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boiteau, Rene M.; Shaw, Jared B.; Pasa-Tolic, Ljiljana

Many elements are scarcely soluble in aqueous conditions found in high pH environments, such as calcareous grassland soils, unless complexed to strong binding organic ligands. To overcome this limitation, some plants and microbes produce chelators that solubilize micronutrient metals such as Fe, Ni, Cu, and Zn from mineral phases. These complexes are taken up by organisms via specific membrane receptors, thereby differentially impacting the bioavailability of these metals to the plant and microbial community. Although the importance of these chelation strategies for individual organisms has been well established, little is known about which pathways coexist within rhizosphere microbiomes or howmore » they interact and compete for metal binding. Identifying these metallophores within natural ecosystems has remained a formidable analytical challenge due to the vast diversity of compounds and poorly defined metabolic processes in complex soil matrices. Herein, we employed recently developed liquid chromatography (LC) mass spectrometry (MS) methods to characterize the speciation of water-soluble dissolved trace elements (Fe, Ni, Cu, and Zn) of soils from native tallgrass prairies in Kansas and Iowa. Both plant and fungal metallophores were identified, revealing compound-specific patterns of chelation to biologically essential metals. Numerous metabolites typically implicated in plant Fe acquisition and homeostasis, including mugineic acids, deoxymugineic acid, nicotianamine, and hydroxynicotianamines, dominated the speciation of divalent metals such as Ni, Cu, and Zn (2–90 pmol/g soil). In contrast, the fungal siderophore ferricrocin was specific for trivalent Fe (7–32 pmol/g soil). These results define biochemical pathways that underpin the regulation of metals in the grassland rhizosphere. They also raise new questions about the competition of these compounds for metal binding and their bioavailability to different members of the rhizosphere population. In conclusion, small structural modifications result in significant differences in metal ligand selectivity, and likely impact metal uptake within the rhizosphere of grassland soils.« less

The importance of trace element speciation in biomedical science.

PubMed

Templeton, Douglas M

2003-04-01

According to IUPAC terminology, trace element speciation reflects differences in chemical composition at multiple levels from nuclear and electronic structure to macromolecular complexation. In the medical sciences, all levels of composition are important in various circumstances, and each can affect the bioavailability, distribution, physiological function, toxicity, diagnostic utility, and therapeutic potential of an element. Here we discuss, with specific examples, three biological principles in the intimate relation between speciation and biological behavior: i) the kinetics of interconversion of species determines distribution within the organism, ii) speciation governs transport across various biological barriers, and iii) speciation can limit potentially undesirable interactions between physiologically essential elements. We will also describe differences in the speciation of iron in states of iron overload, to illustrate how speciation analysis can provide insight into cellular processes in human disease.

Levels and speciation of heavy metals in soils of industrial Southern Nigeria.

PubMed

Olajire, A A; Ayodele, E T; Oyedirdan, G O; Oluyemi, E A

2003-06-01

A knowledge of the total content of trace metals is not enough to fully assess the environmental impact of polluted soils. For this reason, the determination of metal species in solution is important to evaluate their behaviour in the environment and their mobilization capacity. Sequential extraction procedure was used to speciate five heavy metals (Cd, Pb, Cu, Ni and Zn) from four contaminated soils of Southern Nigeria into six operationally defined geochemical species: water soluble, enchangeable, carbonates, Fe-Mn oxide, organic and residual. Metal recoveries were within +/- 10% of the independently determined total Cd, Pb, Cu, Ni and Zn concentrations. The highest amount of Cd (avg. 30%) in the nonresidual fractions was found in the exchangeable fraction, while Cu and Zn were significantly associated with the organic fraction. The carbonate fraction contained on average 14, 18.6, 12.6, 13 and 11% and the residual fraction contained on average 47, 18, 33, 50 and 25% of Cd, Pb, Cu, Ni and Zn respectively. Assuming that mobility and bioavailability of these metals are related to the solubility of the geochemical form of the metals, and that they decrease in the order of extraction sequence, the apparent mobility and potential bioavailability for these five metals in the soil were: Pb > Zn > Cu > Ni > Cd. The mobility indexes of copper and nickel correlated positively and significantly with the total content of metals, while mobility indexes of cadmium and zinc correlated negatively and significantly with the total content of metals.

Speciation, Sources and Bioavailability of Copper and Zinc in DoD-Impacted Harbors and Estuaries

DTIC Science & Technology

2007-03-01

Bioavailability Studies Summary: We developed robust trace metal bioassays using two species of marine phytoplankton (Thalassiosira weissflogi, and Emiliania ...centrales diatom. Cells are 10-12 µm in dimension, and (2) Emiliania huxleyi, a prymnesiophyte with CaCO3 coccoliths. Cells are 4-8 µm in dimension...Thalassiosira weissflogi Centrales Diatom with SiO2 frustules. 10-12 µm. Widely Distributed Emiliania huxleyi Prymnesiophyte with CaCO3 coccoliths

Dissolved and colloidal copper in the tropical South Pacific

NASA Astrophysics Data System (ADS)

Roshan, Saeed; Wu, Jingfeng

2018-07-01

Copper (Cu) as a bioactive trace metal in the ocean has widely been studied in the context of chemical speciation. However, this trace metal is extremely understudied in the context of physical speciation (i.e., size- or molecular weight-partitioning), which may help in characterizing dissolved Cu species. In this study, we determine total dissolved Cu (<0.2 μm) distribution and its physical speciation along the US GEOTRACES 2013 cruise, a 4300-km east-west transect in the tropical South Pacific. The distribution of dissolved Cu is rather uniform horizontally and exhibits a linear increase with depth from surface to 2500-3000 m, below which it varies less significantly both vertically and horizontally. Dissolved Cu shows a strong correlation with silicate (SiO44-) in the upper 1500 m, which is in agreement with previous studies in other regions. This correlation is weaker but with higher slope at depths below 1500 m, which supports the sedimentary source hypothesis. Although hydrothermal activity at the East Pacific Rise (EPR) does not show a readily evident impact on the dissolved Cu distribution, high-quality data at 2300-2800 m allow for diagnosing a subtle westward decrease in the background-subtracted dissolved Cu component. This component of dissolved Cu poorly correlates with mantle-derived 3He (R2 = 0.41), indicating a possible hydrothermal source for dissolved Cu, in contrast to previous studies. For the first time in a major basin, we also determined the physical speciation of dissolved Cu, which shows that Cu species lighter than 10 kDa (Da = 1 g mol-1) dominate the pool of dissolved Cu (<0.2 μm) below 1000 m with a contribution of 61 ± 6% (fraction of total dissolved). 39 ± 6% of dissolved Cu at depths below 1000 m, thus, occurs in the pool of colloidal matter (10 kDa-0.2 μm). Moreover, using a suite of molecular weight cutoffs indicate that Cu species are distributed between two distinct molecular weight classes: the lighter than 5 kDa and heavier than 300 kDa classes, which form 53 ± 6% and 37 ± 7% of dissolved Cu at 2200-2800 m, respectively. The Cu species with molecular weight between 5 kDa and 300 kDa contribute only to 10 ± 12% of the pool at 2200-2800 m. These results offer new insights into structure, reactivity and bioavailability of oceanic Cu compounds. As an organic-dominating metal, Cu physical speciation may also shed light on size-reactivity spectrum of dissolved organic matter (DOM) in the deep ocean.

Influence of dissolved organic matter and manganese oxides on metal speciation in soil solution: A modelling approach.

PubMed

Schneider, Arnaud R; Ponthieu, Marie; Cancès, Benjamin; Conreux, Alexandra; Morvan, Xavier; Gommeaux, Maxime; Marin, Béatrice; Benedetti, Marc F

2016-06-01

Trace element (TE) speciation modelling in soil solution is controlled by the assumptions made about the soil solution composition. To evaluate this influence, different assumptions using Visual MINTEQ were tested and compared to measurements of free TE concentrations. The soil column Donnan membrane technique (SC-DMT) was used to estimate the free TE (Cd, Cu, Ni, Pb and Zn) concentrations in six acidic soil solutions. A batch technique using DAX-8 resin was used to fractionate the dissolved organic matter (DOM) into four fractions: humic acids (HA), fulvic acids (FA), hydrophilic acids (Hy) and hydrophobic neutral organic matter (HON). To model TE speciation, particular attention was focused on the hydrous manganese oxides (HMO) and the Hy fraction, ligands not considered in most of the TE speciation modelling studies in soil solution. In this work, the model predictions of free ion activities agree with the experimental results. The knowledge of the FA fraction seems to be very useful, especially in the case of high DOM content, for more accurately representing experimental data. Finally, the role of the manganese oxides and of the Hy fraction on TE speciation was identified and, depending on the physicochemical conditions of the soil solution, should be considered in future studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

ChelomEx: Isotope-assisted discovery of metal chelates in complex media using high-resolution LC-MS.

PubMed

Baars, Oliver; Morel, François M M; Perlman, David H

2014-11-18

Chelating agents can control the speciation and reactivity of trace metals in biological, environmental, and laboratory-derived media. A large number of trace metals (including Fe, Cu, Zn, Hg, and others) show characteristic isotopic fingerprints that can be exploited for the discovery of known and unknown organic metal complexes and related chelating ligands in very complex sample matrices using high-resolution liquid chromatography mass spectrometry (LC-MS). However, there is currently no free open-source software available for this purpose. We present a novel software tool, ChelomEx, which identifies isotope pattern-matched chromatographic features associated with metal complexes along with free ligands and other related adducts in high-resolution LC-MS data. High sensitivity and exclusion of false positives are achieved by evaluation of the chromatographic coherence of the isotope pattern within chromatographic features, which we demonstrate through the analysis of bacterial culture media. A built-in graphical user interface and compound library aid in identification and efficient evaluation of results. ChelomEx is implemented in MatLab. The source code, binaries for MS Windows and MAC OS X as well as test LC-MS data are available for download at SourceForge ( http://sourceforge.net/projects/chelomex ).

Speciation analysis and bioaccessibility evaluation of trace elements in goji berries (Lycium Barbarum, L.).

PubMed

Wojcieszek, Justyna; Kwiatkowski, Piotr; Ruzik, Lena

2017-04-07

Goji berries (Lycium Barbarum, L.) are known for their nutritional potential as a great source of trace metals (e.g., copper, zinc and manganese) which are present in the form of highly bioaccessible compounds. In order to assess the bioaccessibility of trace elements and to identify compounds responsible for better bioaccessibility of copper and zinc, an in vitro simulation of gastrointestinal digestion was used in this study. The total content of trace metals was evaluated using sample digestion followed by inductively coupled plasma mass spectrometry. Bioaccessibility of trace elements was estimated by size exclusion chromatography coupled to inductively coupled plasma mass spectrometry. These analytical methods were used to analyse samples of goji berries to determine the highest amount of elements. For total trace metal content in goji berries, Zn had the highest level of the three studied (10.6μgg -1 ), while the total content of manganese and copper was 9.9μgg -1 and 6.1μgg -1 , respectively. Additionally, the analysed metals were found to be highly bioaccessible to the human body (about 56% for Mn, 72% for Cu and 64% for Zn in the gastric extract and approximately 35% for Mn, 23% for Cu and 31% for Zn in the case of gastrointestinal extract). To obtain information about metal complexes present in goji berries, extraction treatment using different solutions (ionic liquid, HEPES, SDS, Tris-HCl, ammonium acetate, water) was performed. Enzymatic treatment using pectinase and hemicellulase was also checked. Extracts of berries were analysed by SEC-ICP-MS and μHPLC-ESI-MS/MS techniques. The ionic liquid and pectinase extraction helped efficiently extract copper (seven compounds) and zinc (four compounds) complexes. Compounds identified in goji berries are most likely to be responsible for better bioaccessibility of those elements to the human organism. Copyright © 2017 Elsevier B.V. All rights reserved.

Evolution of Early Paleoproterozoic Ocean Chemistry as Recorded by Black Shales

NASA Astrophysics Data System (ADS)

Scott, C.; Bekker, A.; Lyons, T. W.; Planavsky, N. J.; Wing, B. A.

2010-12-01

In recent years, Precambrian biogeochemists have focused largely on the abundance, speciation and isotopic composition of major and trace elements preserved in organic carbon-rich black shales in order to track the co-evolution of ocean chemistry and life on Earth. Despite the fact that the period from 2.5 to 2.0 Ga hosted major events in Earth’s history, such as the Great Oxidation Event (GOE), an era of global glaciations, a massive and long-lived carbon isotope excursion and the end to banded iron formation (BIF) deposition, each with the potential to directly alter global biogeochemical cycles, it is perhaps best known for its unknowns. In order to help close this gap in our understanding of the evolution of Precambrian ocean chemistry we present a detailed biogeochemical study of Paleoproterozoic black shales deposited between 2.5 and 2.0 Ga. Our study integrates Fe speciation, trace metal chemistry and C, S and N isotope analyses to provide a thorough characterization of marine biogeochemical cycles as they responded to the GOE and set the stage for the demise of BIFs at ca. 1.8 Ga. Our data reveal an ocean that was both surprising similar to, and demonstrably different from, Archean and later Proterozoic oceans. Of particular interest, we find that ferruginous and euxinic conditions co-existed during this period and that sea water trace metal inventories fluctuated dramatically in conjunction with major carbon isotope excursions. By comparing our Paleoproterozoic contribution with recent biogeochemical studies of other Precambrian black shales we can begin to track first order changes in ocean chemistry without the major time gaps that have plagued previous attempts.

Speciation of heavy metals in landfill leachate: a review.

PubMed

Baun, Dorthe L; Christensen, Thomas H

2004-02-01

The literature was reviewed with respect to metal speciation methods in aquatic samples specifically emphasizing speciation of heavy metals in landfill leachate. Speciation here refers to physical fractionation (particulate, colloidal, dissolved), chemical fractionation (organic complexes, inorganic complexes, free metal ions), as well as computer-based thermodynamic models. Relatively few landfill leachate samples have been speciated in detail (less than 30) representing only a few landfills (less than 15). This suggests that our knowledge about metal species in landfill leachate still is indicative. In spite of the limited database and the different definitions of the dissolved fraction (< 0.45 microm or < 0.001 microm) the studies consistently show that colloids as well as organic and inorganic complexes are important for all heavy metals in landfill leachate. The free metal ion constitutes less than 30%, typically less than 10%, of the total metal concentration. This has significant implications for sampling, since no standardized procedures exist, and for assessing the content of metals in leachate in the context of its treatment, toxicity and migration in aquifers.

The determination of trace elements in crude oil and its heavy fractions by atomic spectrometry

NASA Astrophysics Data System (ADS)

Duyck, Christiane; Miekeley, Norbert; Porto da Silveira, Carmem L.; Aucélio, Ricardo Q.; Campos, Reinaldo C.; Grinberg, Patrícia; Brandão, Geisamanda P.

2007-09-01

A literature review on the determination of trace elements in crude oil and heavy molecular mass fractions (saturates, aromatics, resins and asphaltenes) by ICP-MS, ICP OES and AAS is presented. Metal occurrences, forms and distributions are examined as well as their implications in terms of reservoir geochemistry, oil refining and environment. The particular analytical challenges for the determination of metals in these complex matrices by spectrochemical techniques are discussed. Sample preparation based on ashing, microwave-assisted digestion and combustion decomposition procedures is noted as robust and long used. However, the introduction of non-aqueous solvents and micro-emulsions into inductively coupled plasmas is cited as a new trend for achieving rapid and accurate analysis. Separation procedures for operationally defined fractions in crude oil are more systematically applied for the observation of metal distributions and their implications. Chemical speciation is of growing interest, achieved by the coupling of high efficiency separation techniques (e.g., HPLC and GC) to ICP-MS instrumentation, which allows the simultaneous determination of multiple organometallic species of geochemical and environmental importance.

Zinc speciation in the suspended particulate matter of an urban river (Orge, France): influence of seasonality and urbanization gradient.

PubMed

Le Pape, Pierre; Quantin, Cécile; Morin, Guillaume; Jouvin, Delphine; Kieffer, Isabelle; Proux, Olivier; Ghanbaja, Jaafar; Ayrault, Sophie

2014-10-21

Among trace metal pollutants, zinc is the major one in the rivers from the Paris urban area, such as the Orge River, where Zn concentration in the suspended particulate matter (SPM) can reach 2000 mg/kg in the most urbanized areas. In order to better understand Zn cycling in such urban rivers, we have determined Zn speciation in SPM as a function of both the seasonal water flow variations and the urbanization gradient along the Orge River. Using TEM/SEM-EDX and linear combination fitting (LCF) of EXAFS data at the Zn K-edge, we show that Zn mainly occurs as tetrahedrally coordinated Zn(2+) sorbed to ferrihydrite (37-46%), calcite (0-37%), amorphous SiO2 (0-21%), and organic-P (0-30%) and as octahedrally coordinated Zn(2+) in the octahedral layer of phyllosilicates (18-25%). Moreover, the Zn speciation pattern depends on the river flow rate. At low water flow, Zn speciation changes along the urbanization gradient: geogenic forms of Zn inherited from soil erosion decrease relative to Zn bound to organic-phosphates and amorphous SiO2. At high water flow, Zn speciation is dominated by soil-borne forms of Zn regardless the degree of urbanization, indicating that erosion of Zn-bearing minerals dominates the Zn contribution to SPM under such conditions.

Heavy metals fluxes and speciation in the surface layer of urban soils in the province of Brescia (Italy)

NASA Astrophysics Data System (ADS)

Peli, Marco; Raffelli, Giulia; Barontini, Stefano; Bostick, Benjamin C.; Donna, Filippo; Lucchini, Roberto G.; Ranzi, Roberto

2017-04-01

For the last forty years (1974-2015), a ferroalloy industry has been working in Bagnolo Mella, a municipality nearby the city of Brescia (Northern Italy), producing particulate emissions enriched in heavy metals: manganese (Mn) in particular, but also lead (Pb), iron (Fe), aluminum (Al) and arsenic (As). Although some of these metals are required trace elements for most living organisms and can be largely found in natural environments (e.g. Mn being the fifth most abundant metal in the Earth crust), they all lead to toxic effects when they contaminate work and life environments of the exposed population. Aiming at contributing to quantify the exposure of the population to environmental pollution near the factory, as well as the heavy metals possible tendency to migrate through the considered soil matrix, in this work we investigated metals speciation and fluxes within the Earth Critical Zone. The factory is located near residential areas in a plain characterised by little wind and shallow water table with a great number of water resurgences. Three test sites were identified among the pronest ones to particulate matter deposition, on the basis of data collected during a previous experimental field campaign and of the local wind rose. One more site was selected upwind to the factory as a reference site minimally prone to particulate matter deposition, on the basis of the previous investigations. Sites where lawns have been maintained at least for the last forty years where selected in order to avoid agriculture—induced effects on the metals movement. Total soil metal concentrations were measured by means of a portable X-Ray Fluorescence (XRF) device along the soil profiles, down to the depth of 40 cm from the soil surface. Four loose soil samples were collected at each site, at depths ranging from 5 to 30 cm, and they were later subjected to sequential extractions procedure and ICP—MS analyses, in order to investigate differences in heavy metals speciation along the considered soil profiles. The XRF metal total content profiles show an accumulation of metals in the subsurface soil layers, around 5 cm under the soil surface (this feature is highlighted in the normalized profiles). They also give evidence of the plant activity consequences, with the closest downwind site showing values which are for all metals at least one order of magnitude -two for Mn- higher than the ones in the test site. The speciation profiles, besides describing loosely the same pattern, show how the amorphous oxides species is always prevalent for Mn and Pb along the whole profile, while for As the species associated with crystalline oxides is always the prevalent one.

Metal Ion Speciation and Dissolved Organic Matter Composition in Soil Solutions

NASA Astrophysics Data System (ADS)

Benedetti, M. F.; Ren, Z. L.; Bravin, M.; Tella, M.; Dai, J.

2014-12-01

Knowledge of the speciation of heavy metals and the role of dissolved organic matter (DOM) in soil solution is a key to understand metal mobility and ecotoxicity. In this study, soil column-Donnan membrane technique (SC-DMT) was used to measure metal speciation of Cd, Cu, Ni, Pb, and Zn in eighteen soil solutions, covering a wide range of metal sources and concentrations. DOM composition in these soil solutions was also determined. Our results show that in soil solution Pb and Cu are dominant in complex form, whereas Cd, Ni and Zn mainly exist as free ions; for the whole range of soil solutions, only 26.2% of DOM is reactive and consists mainly of fulvic acid (FA). The metal speciation measured by SC-DMT was compared to the predicted ones obtained via the NICA-Donnan model using the measured FA concentrations. The free ion concentrations predicted by speciation modelling were in good agreement with the measurements. Diffusive gradients in thin-films gels (DGT) were also performed to quantify the labile metal species in the fluxes from solid phase to solution in fourteen soils. The concentrations of metal species detected by DGT were compared with the free ion concentrations measured by DMT and the maximum concentrations calculated based on the predicted metal speciation in SC-DMT soil solutions. It is concluded that both inorganic species and a fraction of FA bound species account for the amount of labile metals measured by DGT, consistent with the dynamic features of this technique. The comparisons between measurements using analytical techniques and mechanistic model predictions provided mutual validation in their performance. Moreover, we show that to make accurate modelling of metal speciation in soil solutions, the knowledge of DOM composition is the crucial information, especially for Cu; like in previous studies the modelling of Pb speciation is not optimal and an updated of Pb generic binding parameters is required to reduce model prediction uncertainties.

Toxic heavy metal contamination assessment and speciation in sugarcane soil

NASA Astrophysics Data System (ADS)

Wang, Xiaofei; Deng, Chaobing; Yin, Juan; Tang, Xiang

2018-01-01

The increasing heavy metal pollution in the sugarcane soils along the Great Huanjiang River was caused by leakage and spills of Lead (Pb) and Zinc (Zn) tailing dams during a flood event. Copper (Cu), Zn, Pb, Cadmium (Cd), and Arsenic (As) concentrations of soil samples collected from 16 different sites along the Great Huanjiang River coast typical pollution area were analyzed by Inductive Coupled Plasma Mass Spectrometry (ICP-MS). The mean concentrations of Pb, Cd, Zn, Cu, and As in the sugarcane soils were 151.57 mg/kg, 0.33 mg/kg, 155.52 mg/kg, 14.19 mg/kg, and 18.74 mg/kg, respectively. Results from the analysis of heavy metal speciation distribution showed that Cu, Zn, Pb, and Cd existed in weak acid, reducible, and oxidizable fractions, and the sum of these fractions accounted for significant proportions in sugarcane soils. However, the residual fraction of As with high proportion of reducible fraction indicated that this trace element still poses some environmental risk in the sugarcane soils because of its high content. Assessments of pollution levels revealed that the highest environmental risk was arouse by Pb. In addition, moderate to strong Cd and Zn pollution were found, while As has zero to medium level of pollution and Cu has zero level.

Transformation of heavy metal speciation during sludge drying: mechanistic insights

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weng, Huanxin; Ma, Xue-Wen; Fu, Feng-Xia

2014-01-30

Speciation can fundamentally affect on the stability and toxicity of heavy metals in sludge from wastewater treatment plants. This research investigated the speciation of heavy metals in sludge from both municipal and industrial sources, and metal speciation change as a result of drying process to reduce sludge volume. The changes in sludge properties including sludge moisture content, temperature, density, and electrical conductivity were also monitored to provide insights into the mechanisms causing the change in heavy metal speciation. The results show that the drying process generally stabilized the Cr, Cu, Cd and Pb in sludge by transforming acid-soluble, reducible andmore » oxidizable species into structurally stable forms. Such transformation and stabilization occurred regardless of the sludge source and type, and were primarily caused by the changes in sludge properties associated with decomposition of organic matter and sulfide. The results enhanced our understanding of the geochemical behavior of heavy metals in municipal sludge, and are useful for designing a treatment system for environment-friendly disposal of sludge.« less

Comparative Study of Alternative Fuel Icing Inhibitor Additive Properties & Chemical Analysis of Metal Speciation in Aviation Fuels

DTIC Science & Technology

2010-08-01

paraffins, olefins, cyclo-parafins ( naphthenes ), aromatics and a host of trace species. Petroleum distillates such as jet fuels are also a complex...LC method consisted of: Mobile Phase: 95% CH3OH + 0.1% (vol) Acetic Acid 5% De-Ionized H2O Injection Volume: 5 µL Needle Wash in Flush...Port for 20 seconds using mobile phase CH3OH + 0.1% (vol) Acetic- Acid Run Time: 10 minute Post Time: 1 minute Binary Pump SL Flow Rate: 0.3 ml/min

Relationship between metal speciation in soil solution and metal adsorption at the root surface of ryegrass.

PubMed

Kalis, Erwin J J; Temminghoff, Erwin J M; Town, Raewyn M; Unsworth, Emily R; van Riemsdijk, Willem H

2008-01-01

The total metal content of the soil or total metal concentration in the soil solution is not always a good indicator for metal availability to plants. Therefore, several speciation techniques have been developed that measure a defined fraction of the total metal concentration in the soil solution. In this study the Donnan Membrane Technique (DMT) was used to measure free metal ion concentrations in CaCl(2) extractions (to mimic the soil solution, and to work under standardized conditions) of 10 different soils, whereas diffusive gradients in thin-films (DGT) and scanning chronopotentiometry (SCP) were used to measure the sum of free and labile metal concentrations in the CaCl(2) extracts. The DGT device was also exposed directly to the (wetted) soil (soil-DGT). The metal concentrations measured with the speciation techniques are related to the metal adsorption at the root surface of ryegrass (Lolium perenne L.), to be able to subsequently predict metal uptake. In most cases the metal adsorption related pH-dependently to the metal concentrations measured by DMT, SCP, and DGT in the CaCl(2) extract. However, the relationship between metal adsorption at the root surface and the metal concentrations measured by the soil-DGT was not-or only slightly-pH dependent. The correlations between metal adsorption at the root surface and metal speciation detected by different speciation techniques allow discussion about rate limiting steps in biouptake and the contribution of metal complexes to metal bioavailability.

Urban legacies and soil management affect the concentration and speciation of trace metals in Los Angeles community garden soils.

PubMed

Clarke, Lorraine Weller; Jenerette, G Darrel; Bain, Daniel J

2015-02-01

Heavy metals in urban soils can compromise human health, especially in urban gardens, where gardeners may ingest contaminated dust or crops. To identify patterns of urban garden metal contamination, we measured concentrations and bioavailability of Pb, As, and Cd in soils associated with twelve community gardens in Los Angeles County, CA. This included sequential extractions to partition metals among exchangeable, reducible, organic, or residual fractions. Proximity to road increased all metal concentrations, suggesting vehicle emissions sources. Reducible Pb increased with neighborhood age, suggesting leaded paint as a likely pollutant source. Exchangeable Cd and As both increased with road proximity. Only cultivated soils showed an increase in exchangeable As with road proximity, potentially due to reducing humic acid interactions while Cd bioavailability was mitigated by organic matter. Understanding the geochemical phases and metal bioavailability allows incorporation of contamination patterns into urban planning. Copyright © 2014 Elsevier Ltd. All rights reserved.

Assessment of a sequential extraction protocol by examining solution chemistry and mineralogical evolution

NASA Astrophysics Data System (ADS)

Maubec, Nicolas; Pauwels, Hélène; Noël, Hervé; Bourrat, Xavier

2015-04-01

Knowledge of the behavior of heavy metals, such as copper and zinc in sediments, is a key factor to improve the management of rivers. The mobility of these metals, which may be harmful to the environment, depends directly on their concentration and speciation , which in turn depend on physico-chemical parameters such as mineralogy of the sediment fraction, pH, redox potential, salinity etc ... (Anderson et al., 2000; Sterckeman et al., 2004; Van Oort et al., 2008). Several methods based on chemical extractions are currently applied to assess the behavior of heavy metals in soils and sediments. Among them, sequential extraction procedure is widely used in soil and sediment science and provides details about the origin, biological and physicochemical availability, mobilization and transports of trace metals elements. It is based on the use of a series of extracting reagents to extract selectively heavy metals according to their association within the solid phase (Cornu and Clozel, 2000) including the following different fraction : exchangeable, bound to carbonates, associated to oxides (reducible fraction), linked to organic matter and sulfides (oxidizable fraction) as well as silicate minerals so called residual fraction (Hickey and Kittrick, 1984; Tessier et al., 1979). Consequently sequential extraction method is expected to simulate a lot of potential natural and anthropogenic modifications of environmental conditions (Arey et al., 1999; Brannon and Patrick, 1987; Hickey and Kittrick, 1984; La Force et al., 1999; Tessier et al., 1979). For three decades, a large number of protocols has been proposed, characterized by specific reagents and experimental conditions (concentrations, number of steps, extraction orders and solid/solution ratio) (Das et al., 1995; Gomez Ariza et al., 2000; Quevauviller et al., 1994; Rauret, 1998; Tack and Verloo, 1995), but it appeared that several of them suffer from a lack of selectivity of applied reagents: besides target ones, some of them are able to leach several solid phases. In this context, the aim of the present study is to investigate the effectiveness and the selectivity of different reagents for metal extraction from target geochemical fraction. It is based on solid analyses with the use of X-ray diffraction and a scanning electron microscopy (SEM) coupled to a microRaman spectrometer in conjunction with chemical analyses of extracting solutions at each step. This methodology provides the opportunity to assess more accurately the effect of each reagent. The study focuses on extraction of Cu and Zn from sediment samples collected at two sites from river banks and characterized by presence of Quartz, Feldspar K, Micas, Kaolinite but with differences regarding accessory phases (pyrite, organic matter, iron oxy- hydroxide, calcite). The interaction of the samples with eight different reagents was assessed and compared (Ca(NO3)2 and CaCl2 for the exchangeable fraction; buffered solutions of sodium acetate/acetic acid at pH = 5.5 and pH = 5 for the acido-soluble fraction; hydroxylamine hydrochloride and a solution of ammonium oxalate/oxalic acid for reducible fraction; hydrogen peroxide and sodium hypochlorite for the oxidizable fraction. In-depth characterization of solid residue at each step allowed proposing the best protocol for both metals. Anderson, P., Davidson, C. M., Duncan, A. L., Littlejohn, D., Ure, A. M., and Garden, L. M. (2000). Column leaching and sorption experiments to assess the mobility of potentially toxic elements in industrially contaminated land. Journal of Environmental Monitoring, 2. Arey, J. S., Seaman, J. C., and Bertsch, P. M. (1999). Immobilization of uranium in contaminated sediments by hydroxyapatite addition. Environmental Science & Technology, 33, 337-342. Brannon, J. M., and Patrick, W. H. (1987). Fixation, transformation, and mobilization of arsenic in sediments.Environmental Science & Technology, 21, 450-459. Cornu, S., and Clozel, B. (2000). Extractions séquentielles et spéciation des éléments trace métalliques dans les sols naturels. Analyse critique. 7, 179-189. Das, A. K., Chakraborty, R., Cervera, M. L., and Delaguardia, M. (1995). Metal speciation in solid matrices. Talanta, 42. Gomez Ariza, J. L., Giraldez, I., Sanchez-Rodas, D., and Morales, E. (2000). Selectivity assessment of a sequential extraction procedure for metal mobility characterization using model phases. Talanta, 52, 545-554. Hickey, M. G., and Kittrick, J. A. (1984). Chemical partitioning of cadmium, copper, nickel and zinc in soils and sediments containing high-levels of heavy metals. Journal of Environmental Quality, 13, 372-376. La Force, M. J., Fendorf, S., Li, G. C., and Rosenzweig, R. F. (1999). Redistribution of trace elements from contaminated sediments of Lake Coeur d'Alene during oxygenation. Journal of Environmental Quality, 28, 1195-1200. Quevauviller, P., Rauret, G., Muntau, H., Ure, A. M., Rubio, R., Lopezsanchez, J. F., Fiedler, H. D., and Griepink, B. (1994). Evaluation of a sequential extraction procedure for the determination of extractable trace-metal contents in sediments. Fresenius Journal of Analytical Chemistry, 349. Rauret, G. (1998). Extraction procedures for the determination of heavy metals in contaminated soil and sediment. Talanta, 46(3), 449-455. Sterckeman, T., Douay, F., Baize, D., Fourrier, H., Proix, N., and Schvartz, C. (2004). Factors affecting trace element concentrations in soils developed on recent marine deposits from northern France. Applied Geochemistry, 19. Tack, F. M. G., and Verloo, M. G. (1995). Chemical speciation and fraéctination in soil and sediment heavy-metal analysis - a review. International Journal of Environmental Analytical Chemistry, 59, 225-238. Tessier, A., Campbell, P. G. C., and Bisson, M. (1979). Sequential extraction procedure for the speciation of particulate trace-metals. Analytical Chemistry, 51. Van Oort, F., Jongmans, A. G., Lamy, I., Baize, D., and Chevallier, P. (2008). Impacts of long-term waste-water irrigation on the development of sandy Luvisols: consequences for metal pollutant distributions. European Journal of Soil Science, 59.

Molybdenum drawdown during Cretaceous Oceanic Anoxic Event 2

NASA Astrophysics Data System (ADS)

Goldberg, Tatiana; Poulton, Simon W.; Wagner, Thomas; Kolonic, Sadat F.; Rehkämper, Mark

2016-04-01

During the Cretaceous greenhouse, episodes of widespread ocean deoxygenation were associated with globally occurring events of black shale deposition. Possibly the most pronounced of these oceanic anoxic events (OAE's) was the Cenomanian-Turonian OAE2 (∼94 Ma). However, although certain redox sensitive trace metals tend to be preferentially sequestered in sediments deposited under anoxic conditions, with Mo drawdown being specifically prone to euxinic settings, these elements are generally somewhat depleted in sediments deposited during OAE2. To understand the driving factors responsible for this depleted trace metal drawdown, we have studied a low latitude section from the proto-North Atlantic Ocean (Tarfaya S57), where existing biomarker and iron-sulphur data point to a dominantly euxinic water column, with periodic transitions to ferruginous (Fe-rich) water column conditions. We utilise a variety of redox proxies (Fe-speciation, redox sensitive trace metals and Mo isotopes), which, in combination, allows us to evaluate the detailed nature of ocean redox conditions and hence controls on trace metal drawdown. The results suggest that seawater δ98Mo values may have ranged between ∼0.6 and 1.1‰ during OAE2, likely connected to changes in the local Mo reservoir as a consequence of low and probably heterogeneous concentrations of Mo in the ocean. The very low Mo/TOC ratios at Tarfaya and elsewhere in the proto-North Atlantic may support a model in which deep-water circulation was partially restricted within and between the North Atlantic and other ocean basins. We propose that the combination of a low and possibly heterogeneous δ98Mo of seawater Mo, together with low Mo/TOC ratios, points to a large decrease in the global oceanic Mo reservoir during OAE2, reflecting a major global scale increase in Mo drawdown under persistent euxinic conditions.

Ocean acidification modulates the incorporation of radio-labeled heavy metals in the larvae of the Mediterranean sea urchin Paracentrotus lividus.

PubMed

Dorey, Narimane; Martin, Sophie; Oberhänsli, François; Teyssié, Jean-Louis; Jeffree, Ross; Lacoue-Labarthe, Thomas

2018-10-01

The marine organisms which inhabit the coastline are exposed to a number of anthropogenic pressures that may interact. For instance, the accumulation of toxic metals present in coastal waters is expected to be modified by ocean acidification through e.g. changes in physiological performance and/or elements availability. Changes in bioaccumulation due to lowering pH are likely to be differently affected depending on the nature (essential vs. non-essential) and speciation of each element. The Mediterranean is of high concern for possible cumulative effects due to strong human influences on the coastline. The aim of this study was to determine the effect of ocean acidification (from pH 8.1 down to -1.0 pH units) on the incorporation kinetics of six trace metals (Mn, Co, Zn, Se, Ag, Cd, Cs) and one radionuclide ( 241 Am) in the larvae of an economically- and ecologically-relevant sea urchin of the Mediterranean coastline: Paracentrotus lividus. The radiolabelled metals and radionuclides added in trace concentrations allowed precise tracing of their incorporation in larvae during the first 74 h of their development. Independently of the expected indirect effect of pH on larval size/developmental rates, Paracentrotus lividus larvae exposed to decreasing pHs incorporated significantly more Mn and Ag and slightly less Cd. The incorporation of Co, Cs and 241 Am was unchanged, and Zn and Se exhibited complex incorporation behaviors. Studies such as this are necessary prerequisites to the implementation of metal toxicity mitigation policies for the future ocean. We discuss possible reasons and mechanisms for the specific effect of pH on each metals. Copyright © 2018 Elsevier Ltd. All rights reserved.

Capillary electrophoresis application in metal speciation and complexation characterization

USDA-ARS?s Scientific Manuscript database

Capillary electrophoresis is amenable to the separation of metal ionic species and the characterization of metal-ligand interactions. This book chapter reviews and discusses three representative case studies in applications of CE technology in speciation and reactions of metal with organic molecules...

Abundance, distribution and bioavailability of major and trace elements in surface sediments from the Cai River estuary and Nha Trang Bay (South China Sea, Vietnam)

NASA Astrophysics Data System (ADS)

Koukina, S. E.; Lobus, N. V.; Peresypkin, V. I.; Dara, O. M.; Smurov, A. V.

2017-11-01

Major (Si, Al, Fe, Ti, Mg, Ca, Na, K, S, P), minor (Mn) and trace (Li, V, Cr, Co, Ni, Cu, Zn, As, Sr, Zr, Mo, Cd, Ag, Sn, Sb, Cs, Ba, Hg, Pb, Bi and U) elements, their chemical forms and the mineral composition, organic matter (TOC) and carbonates (TIC) in surface sediments from the Cai River estuary and Nha Trang Bay were first determined along the salinity gradient. The abundance and ratio of major and trace elements in surface sediments are discussed in relation to the mineralogy, grain size, depositional conditions, reference background and SQG values. Most trace-element contents are at natural levels and are derived from the composition of rocks and soils in the watershed. A severe enrichment of Ag is most likely derived from metal-rich detrital heavy minerals such as Ag-sulfosalts. Along the salinity gradient, several zones of metal enrichment occur in surface sediments because of the geochemical fractionation of the riverine material. The parts of actually and potentially bioavailable forms (isolated by four single chemical reagent extractions) are most elevated for Mn and Pb (up to 36% and 32% of total content, respectively). The possible anthropogenic input of Pb in the region requires further study. Overall, the most bioavailable parts of trace elements are associated with easily soluble amorphous Fe and Mn oxyhydroxides. The sediments are primarily enriched with bioavailable metal forms in the riverine part of the estuary. Natural (such as turbidities) and human-generated (such as urban and industrial activities) pressures are shown to influence the abundance and speciation of potential contaminants and therefore change their bioavailability in this estuarine system.

Oxygen Oases Before and After the GOE: Insights From Metals and Models

NASA Astrophysics Data System (ADS)

Olson, S. L.; Reinhard, C. T.; Planavsky, N. J.; Lyons, T. W.; Roy, M.; Anbar, A. D.

2014-12-01

The evolution of oxygenic photosynthesis fundamentally changed the structure of the marine biosphere and the chemistry of Earth's ocean-atmosphere system. Atmospheric oxygenation, however, was decoupled from the onset of biological O2 production—possibly lagging by as much as half a billion years—and O2 remained low for two billion years following initial O2 accumulation. Although uncertainties remain regarding the fate of biogenic O2 during the Precambrian, it is becoming clear that the consequences of oxygenesis were both spatially and temporally variable. Several lines of evidence support the existence of aerobic ecosystems associated with O2 oases within an otherwise anoxic Archean ocean; however—with notable exceptions—atmospheric O2 remained low enough to severely curtail oxidative weathering processes on long-term average throughout the Archean. During the subsequent Great Oxidation Event (GOE) in the early Paleoproterozoic, atmospheric O2 irreversibly increased above the sensitivity thresholds of several well-established proxies, but the level at which O2 eventually stabilized remains unclear. Consequently, the dynamics of O2 cycling are poorly characterized both before and after the GOE. Nevertheless, recent analytical and numerical results suggest exceptionally low O2 levels that may have favored Archean-style O2 oases in the mid-Proterozoic. We used Fe speciation and trace metal records from Precambrian shales, including data from two new cores that target the 2.7 Ga Roy Hill Shale, to investigate pre- and post- GOE redox heterogeneity in Earth's surface environments. Fe speciation supports the reconstruction of local marine redox conditions, and, in this context, trace metals can allow glimpses of redox conditions beyond the local environment, which may have throttled the supply of key redox-sensitive trace metals to the ocean. Then, using O2 constraints derived from these inorganic proxies, we use an Earth System model to explore C, O, and nutrient cycling in the late Archean and into the mid-Proterozoic. Although our results allow profound perturbation to several biogeochemical cycles and the climate system as a result of the GOE, we find that the GOE may have had only minor significance for the long-term average O2 content of typical surface seawater in the Proterozoic.

Transformation of heavy metal speciation during sludge drying: mechanistic insights.

PubMed

Weng, Huan-Xin; Ma, Xue-Wen; Fu, Feng-Xia; Zhang, Jin-Jun; Liu, Zan; Tian, Li-Xun; Liu, Chongxuan

2014-01-30

Speciation can fundamentally affect on the stability and toxicity of heavy metals in sludge from wastewater treatment plants. This research investigated the speciation of heavy metals in sludge from both municipal and industrial sources, and metal speciation change as a result of drying process to reduce sludge volume. The changes in sludge properties including sludge moisture content, temperature, density, and electrical conductivity were also monitored to provide insights into the mechanisms causing the change in heavy metal speciation. The results show that the drying process generally stabilized Cr, Cu, Cd, and Pb in sludge by transforming acid-soluble, reducible, and oxidizable species into structurally stable forms. Such transformation and stabilization occurred regardless of the sludge source and type, and were primarily caused by the changes in sludge properties associated with decomposition of organic matter and sulfide. The results enhanced our understanding of the geochemical behavior of heavy metals in municipal sludge, and are useful for designing a treatment system for environment-friendly disposal of sludge. Copyright © 2013 Elsevier B.V. All rights reserved.

Speciation distribution and mass balance of copper and zinc in urban rain, sediments, and road runoff.

PubMed

Zuo, Xiaojun; Fu, Dafang; Li, He

2012-11-01

Heavy metal pollution in road runoff had caused widespread concern since the last century. However, there are little references on metal speciation in multiple environmental media (e.g., rain, road sediments, and road runoff). Our research targeted the investigation of metal speciation in rain, road sediments, and runoff; the analysis of speciation variation and mass balance of metals among rain, road sediments, and runoff; the selection of main factors by principal component analysis (PCA); and the establishment of equation to evaluate the impact of rain and road sediments to metals in road runoff. Sequential extraction procedure contains five steps for the chemical fractionation of metals. Flame atomic absorption spectrometry (Shimadzu, AA-6800) was used to determine metal speciation concentration, as well as the total and dissolved fractions. The dissolved fractions for both Cu and Zn were dominant in rain. The speciation distribution of Zn was different from that of Cu in road sediments, while speciation distribution of Zn is similar to that of Cu in runoff. The bound to carbonates for both Cu and Zn in road sediments were prone to be dissolved by rain. The levels of Cu and Zn in runoff were not obviously influenced by rain, but significantly influenced by road sediments. The masses for both Cu and Zn among rain, road sediments, and road runoff approximately meet the mass balance equation for all rainfall patterns. Five principal factors were selected for metal regression equation based on PCA, including rainfall, average rainfall intensity, antecedent dry periods, total suspended particles, and temperature. The established regression equations could be used to predict the effect of road runoff on receiving environments.

Concentrations and chemical forms of trace metals in coastal seawater on coral reef and their seasonal variation

NASA Astrophysics Data System (ADS)

Ganaha, S.; ITOH, A.

2011-12-01

Coastal seawater on coral reef near Okinawa island in Japan, which is in oligotrophic condition, has a diverse and unique ecosystem. It is possible that nutritive sals and trace metals, classified into nutrient type, are effectively supplied to marine phytoplankton and zooxanthellae from seawater. However, the concentrations and chemical forms of trace metals in coastal seawater on coral reef have been scarcely reported so far. In the present study, the characteristics of the concentrations and chemical forms of trace metals in such a seawater were investigated with seasonal variation by analyzing the coastal seawater at every month, after an analytical method for a simple chemical speciation including on-site treatment was established. The analytical method using a chelating resin and a disposable syringe was employed for de-salt and preconcentration of trace metals in costal seawater. After that, trace metals in the concentrated solution were measured by ICP-MS. Three types of chemical forms of an ionic, a dissolved, and an acid-soluble were separated without any treatment, by filtering with membrane filter of 0.45 μm, and by filtering after adding nitric acid, respectively. Then, a monitoring investigation of the coastal seawater on coral reef, located at Sesoko island near the northern part of Okinawa island, was carried out once at every month from Sep. 2010 to Aug. 2011. As a result, 10 elements in the dissolved form in each sample could be determined. The average concentrations for all samples from Sep. 2010 to Apr. 2011 were as follows: Mo:10.7 ppb, U:3.2 ppb, V:1.5 ppb, Mn:0.17 ppb, Ni:0.16 ppb, Zn:0.13 ppb, Cu:0.070 ppb, Pb:0.024 ppb, Co:0.0022 ppb, Cd:0.0016ppb. The concentrations for most trace metals were almost close to ones in open surface seawater of the Pacific ocean. For the acid-soluble form, the concentrations of V, Mo, and U were almost same with those of the dissolved form, and ones of Mn, Co, Ni, Cu, and Cd were slightly larger than ones in the dissolved form, while ones in Zn and Pb were 3.1- and 2.5-fold larger. These results suggest that a part of trace metals in the nutrient type exists as biogenic particulate matters. For the ionic form, the concentration of Cu was 3-fold smaller than one in the dissolved form. It is considered from the result that a part of Cu in the dissolved form exists not only as the ionic form but also as the colloids and organic complexes. The seasonal variation for each chemical form is now being investigated.

CORRELATING METAL SPECIATION IN SOILS

EPA Science Inventory

Understanding bioavailability of metals from exposure to contaminated soils is a challenging aspect of environmental research. This presentation will examine three areas of research with respect to metal speciation in soils as it relates to bioavailability: 1) Pb immobilization a...

Effects of calcium, magnesium, and sodium on alleviating cadmium toxicity to Hyalella azteca

USGS Publications Warehouse

Jackson, B.P.; Lasier, P.J.; Miller, W.P.; Winger, P.V.

2000-01-01

Toxicity of trace metal ions to aquatic organisms, arising through either anthropogenic inputs or acidification of surface waters, continues to be both a regulatory and environmental problem. It is generally accepted that the free metal ion is the major toxic species (Florence et a1.,1992) and that inorganic or organic complexation renders the metal ion non-bioavailable (Meador, 1991, Galvez and Wood, 1997). However, water chemistry parameters such as alkalinity, hardness, dissolved organic carbon and pH influence metal ion toxicity either directly by lowering free metal ion concentration or indirectly through synergistic or antagonistic effects. Alkalinity and salinity can affect the speciation of metal ions by increasing ion-pair formation, thus decreasing free metal ion concentration. For example, Cu was found to be less toxic to rainbow trout in waters of high alkalinity (Miller and Mackay, 1980), due to formation of CuCO3 ion pair, and corresponding reduction in free Cu2+ concentration. The influence of salinity on the toxicity of cadmium to various organisms has been demonstrated in a number of studies (Bervoets et al., 1995, Hall et al., 1995, Lin and Dunson, 1993, Blust et al., 1992). In all these studies the apparent toxicity of cadmium was lowered as salinity was increased due to increased formation of CdC1+ and CDCl2 aqueous complexes that are non-toxic or of much lower toxicity than the free Cd2+ ion. Changes in pH exert both a biological and chemical effect on metal ion toxicity (Campbell and Stokes, 1985). Low pH favors greater metal ion solubility, and, in the absence of complexing ions, reduced speciation of the metal ion, which tends to increase toxicity compared to higher pH. However, Iow pH also enhances competition between H+ and metal ion for cell surface binding sites, which tends to decrease metal ion toxicity.

Comparison between fractionation and bioavailability of trace elements in rhizosphere and bulk soils.

PubMed

Wang, Zhongwen; Shan, Xiao-Quan; Zhang, Shuzhen

2002-03-01

Rhizosphere is a microbiosphere and has quite different chemical, physical and biological properties from bulk soils. A greenhouse experiment was performed to compare the difference of fractionation and bioavailability of trace elements Cr, Ni, Zn, Cu, Pb and Cd between rhizosphere soil and bulk soil. In the meantime, the influence of air-drying on the fractionation and bioavailability was also investigated by using wet soil sample as a control. Soils in a homemade rhizobox were divided into four zones: rhizosphere, near rhizosphere, near bulk soil and bulk soil zones, which was designated as S1, S2, S3 and S4. Elemental speciations were fractionated to water soluble, exchangeable and carbonate bound (B1), Fe-Mn oxide bound (B2), and organic and sulfide bound (B3) by a sequential extraction procedure. Speciation differences were observed for elements Cr, Ni, Zn, Cu, Pb and Cd between the rhizosphere and bulk soils, and between the air-dried and wet soils as well. The concentrations of all six heavy metals in fraction B1 followed the order of S2 > S3 > S1 > S4 and for B2, the order was S2 > S3 S4 > S1. For B3, the order was S1 > S3 S4 > S2, while for Cd the order was S2 > S3 approximately/= S4 > S1. The air-drying increased elemental concentration in fractions B1 and B2 by 20-50% and decreased in fraction B3 by about 20-100%. Correlation analysis also indicated that the bioavailability correlation coefficient of fraction B1 in rhizosphere wet soil to plants was better than that between either air-dried or nonrhizosphere soils. Therefore, application of rhizosphere wet soils should be recommended in the future study on the speciation analysis of trace elements in soils and bioavailability.

Speciation analysis and leaching behaviors of selected trace elements in spent SCR catalyst.

PubMed

Dai, Zejun; Wang, Lele; Tang, Hao; Sun, Zhijun; Liu, Wei; Sun, Yi; Su, Sheng; Hu, Song; Wang, Yi; Xu, Kai; Liu, Liang; Ling, Peng; Xiang, Jun

2018-09-01

This study investigated heavy metal chemical speciation and leaching behavior from a board-type spent selective catalytic reduction (SCR) catalyst containing high concentrations of vanadium, chromium, nickel, copper, zinc, and lead. A three-step sequential extraction method, standard toxicity characteristic leaching procedure (TCLP), and leaching characteristic tests have been performed. It was found that the mobility of six heavy metals in the spent SCR catalyst was significantly different. The mobility of the six heavy metals exhibited the following order: Ni > Zn > V > Cr > As > Cu. Meanwhile, TCLP test results revealed relatively high Zn and Cr leaching rate of 83.20% and 10.35%, respectively. It was found that leaching rate was positively correlated with available contents (sum of acid soluble, reducible and oxidizable fractions). Leaching characteristics tests indicated that pH substantially affected the leaching of these heavy metals. In particular, the leaching of Cr, Ni, Cu, and Zn was positively influenced by strong acid, while V and As were easily released in the presence of strong acid and strong alkali (pH < 3 or pH > 11). In terms of kinetics, the leaching of Cr, Ni, Cu, Zn, and As within the spent catalyst was dominated by erosion and dissolution processes, which were rapid reaction processes. V was released in large amounts within 1 h, but its leaching amount sharply decreased with time due to readsorption. Copyright © 2018 Elsevier Ltd. All rights reserved.

The geochemical cycling of trace elements in a biogenic meromictic lake

NASA Astrophysics Data System (ADS)

Balistrieri, Laurie S.; Murray, James W.; Paul, Barbara

1994-10-01

The geochemical processes affecting the behavior and speciation of As, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn in Hall Lake, Washington, USA, are assessed by examining dissolved and acid soluble particulate profiles of the elements and utilizing results from thermodynamic calculations. The water column of this meromictic lake is highly stratified and contains distinctive oxic, suboxic, and anoxic layers. Changes in the redox state of the water column with depth affect the distribution of all the elements studied. Most noticeable are increases in dissolved Co, Cr, Fe, Mn, Ni, Pb, and Zn concentrations across the oxic-suboxic boundary, increases in dissolved As, Co, Cr, Fe, Mn, and V concentrations with depth in the anoxic layer, significant decreases in dissolved Cu, Ni, Pb, and Zn concentrations in the anoxic region below the sulfide maximum, and large increases in acid soluble particulate concentrations of As, Cr, Cu, Fe, Mo, Ni, Pb, V, and Zn in the anoxic zone below the sulfide maximum. Thermodynamic calculations for the anoxic region indicate that all redox sensitive elements exist in their reduced forms, the primary dissolved forms of Cu, Ni, Pb, and Zn are metal sulfide solution complexes, and solid sulfide phases of Cu, Fe, Mo, and Pb are supersaturated. Calculations using a vertical diffusion and reaction model indicate that the oxidation rate constant for Mn(II) in Hall Lake is estimated to be 0.006 d -1 and is at the lower end of the range of microbial oxidation rates observed in other natural systems. The main geochemical processes influencing the distribution and speciation of trace elements in Hall Lake appear to be transformations of dissolved elements between their oxidation states (As, Cr, Cu, Fe, Mn, V), cocycling of trace elements with Mn and Fe (As, Co, Cr, Cu, Mo, Ni, Pb, V, Zn), formation of soluble metal sulfide complexes (Co, Cu, Ni, Pb, Zn), sorption (As, Co, Cr, Ni, V), and precipitation (Cu, Fe, Mn, Mo, Pb, Zn).

The geochemical cycling of trace elements in a biogenic meromictic lake

USGS Publications Warehouse

Balistrieri, L.S.; Murray, J.W.; Paul, B.

1994-01-01

The geochemical processes affecting the behavior and speciation of As, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, V, and Zn in Hall Lake, Washington, USA, are assessed by examining dissolved and acid soluble particulate profiles of the elements and utilizing results from thermodynamic calculations. The water column of this meromictic lake is highly stratified and contains distinctive oxic, suboxic, and anoxic layers. Changes in the redox state of the water column with depth affect the distribution of all the elements studied. Most noticeable are increases in dissolved Co, Cr, Fe, Mn, Ni, Pb, and Zn concentrations across the oxic-suboxic boundary, increases in dissolved As, Co, Cr, Fe, Mn, and V concentrations with depth in the anoxic layer, significant decreases in dissolved Cu, Ni, Pb, and Zn concentrations in the anoxic region below the sulfide maximum, and large increases in acid soluble particulate concentrations of As, Cr, Cu, Fe, Mo, Ni, Pb, V, and Zn in the anoxic zone below the sulfide maximum. Thermodynamic calculations for the anoxic region indicate that all redox sensitive elements exist in their reduced forms, the primary dissolved forms of Cu, Ni, Pb, and Zn are metal sulfide solution complexes, and solid sulfide phases of Cu, Fe, Mo, and Pb are supersaturated. Calculations using a vertical diffusion and reaction model indicate that the oxidation rate constant for Mn(II) in Hall Lake is estimated to be 0.006 d-1 and is at the lower end of the range of microbial oxidation rates observed in other natural systems. The main geochemical processes influencing the distribution and speciation of trace elements in Hall Lake appear to be transformations of dissolved elements between their oxidation states (As, Cr, Cu, Fe, Mn, V), cocycling of trace elements with Mn and Fe (As, Co, Cr, Cu, Mo, Ni, Pb, V, Zn), formation of soluble metal sulfide complexes (Co, Cu, Ni, Pb, Zn), sorption (As, Co, Cr, Ni, V), and precipitation (Cu, Fe, Mn, Mo, Pb, Zn). ?? 1994.

CORRELATING METAL SPECIATION IN SOILS TO RISK

EPA Science Inventory

Understanding bioavailability of metals from exposure to contaminated soils is a challenging aspect of environmental research. This presentation will examine three areas of research with respect to metal speciation in soils as it relates to bioavailability: 1) Pb immobilization a...

Concentration, Complexation and Chemical Speciation of Zinc and Cadmium in the Western North Pacific Ocean : Exploring Sources and Transport of Trace Metals and Complexing Ligands.

NASA Astrophysics Data System (ADS)

Carrasco, G. G.; Morton, P. L.; Donat, J. R.

2008-12-01

We determined Zn and Cd total dissolved (0.45 µm-filtered) concentrations, organic complexation and chemical speciation in surface water samples collected along the transect of the 2002 IOC Baseline Contaminant Survey expedition in the Western North Pacific and in vertical profile water samples at nine stations. The goals of this work were (1) to compare and contrast various trace metal sources, including both natural and anthropogenic atmospheric deposition, upwelling, marginal seas and others; (2) to study the organic ligand sources, generally thought to be phytoplankton; and (3) to investigate metal and ligand transport mechanisms, residence times and eventual upwelling in the Eastern North Pacific. Total dissolved (TD) Zn and Cd values were obtained using a combination of differential pulse stripping anodic voltammetry (DPASV), preconcentration with 8-HQ or APDC/DDC and quantification at ICPMS or AA. Organic complexation and chemical speciation of Zn and Cd were determined simultaneously using DPASV at a thin-mercury-film, glassy-carbon-disk-electrode. Surface transect TDZn and TDCd concentrations were low in the Subtropical Gyre (STG), in contrast with high values in the Western Subarctic Gyre (WSG). Zn and Cd were organically complexed in most surface samples: at least one ligand class was detected for Zn and Cd, whose conditional stability constants (log K') averaged 10.2 and 10.5, respectively. These ligands were found in excess of the total dissolved metal throughout the region of study except in the WSG for Cd. Vertical distributions of TDZn and TDCd exhibited nutrient-type profiles for all the STG stations. While constant Zn/Si and Cd/P values were observed throughout the water column in the WSG, some deviations were observed within the STG. In addition, the mode and intermediate water masses of the STG displayed very high concentrations of a Zn-complexing ligand (log K' 10.0) in excess of TDZn. As these water masses moved eastward, we observed that the ligand concentrations decreased. In contrast to the STG, the upper 1000m of the WSG showed elevated concentrations of both metals. Despite elevated surface (0-200m) Zn concentrations (~2nM), a Zn-complexing ligand (log K' 9.8) was found in excess of TDZn; below the photic layer, even higher TDZn concentrations might have saturated the ligand. A ligand for Cd was present in lower-than-TDCd concentrations in the same surface waters; below them, organic complexation of Cd was observed rarely in both STG and WSG regions. By studying the geographic distribution of the total dissolved metals and ligands, along with other dissolved and particulate tracers, possible sources and transport mechanisms can be contrasted and evaluated. Furthermore, the influence of these sources and transport mechanisms on the distribution of Zn and Cd chemical species and, ultimately, the bioavailability of these micronutrient metals can be studied.

Microcolumn-based speciation analysis of thallium in soil and green cabbage.

PubMed

Jia, Yanlong; Xiao, Tangfu; Sun, Jialong; Yang, Fei; Baveye, Philippe C

2018-07-15

Thallium (Tl) is a toxic trace metal, whose geochemical behavior and biological effects are closely controlled by its chemical speciation in the environment. However, little tends to be known about this speciation of Tl in soil and plant systems that directly affect the safety of food supplies. In this context, the objective of the present study was to elaborate an efficient method to separate and detect Tl(I) and Tl(III) species for soil and plant samples. This method involves the selective adsorption of Tl(I) on microcolumns filled with immobilized oxine, in the presence of DTPA (diethylenetriaminepentaacetic acid), followed by DTPA-enhanced ultrasonic and heating-induced extraction, coupled with ICP-MS detection. The method was characterized by a LOD of 0.037 μg/L for Tl(I) and 0.18 μg/L for Tl(III) in 10  mL samples. With this method, a second objective of the research was to assess the speciation of Tl in pot and field soils and in green cabbage crops. Experimental results suggest that DTPA extracted Tl was mainly present as Tl(I) in soils (>95%). Tl in hyperaccumulator plant green cabbage was also mainly present as Tl(I) (>90%). With respect to Tl uptake in plants, this study provides direct evidence that green cabbage mainly takes up Tl(I) from soil, and transports it into the aboveground organs. In soils, Tl(III) is reduced to Tl(I) even at the surface where the chemical environment promotes oxidation. This observation is conducive to understanding the mechanisms of Tl isotope fractionation in the soil-plant system. Based on geochemical fraction studies, the reducible fraction was the main source of Tl getting accumulated by plants. These results indicate that the improved analytical method presented in this study offers an economical, simple, fast, and sensitive approach for the separation of Tl species present in soils at trace levels. Copyright © 2018 Elsevier B.V. All rights reserved.

Quantitative Zn speciation in a contaminated dredged sediment by μ-PIXE, μ-SXRF, EXAFS spectroscopy and principal component analysis

NASA Astrophysics Data System (ADS)

Isaure, Marie-Pierre; Laboudigue, Agnès; Manceau, Alain; Sarret, Géraldine; Tiffreau, Christophe; Trocellier, Patrick; Lamble, Géraldine; Hazemann, Jean-Louis; Chateigner, Daniel

2002-05-01

Dredging and disposal of sediments onto agricultural soils is a common practice in industrial and urban areas that can be hazardous to the environment when the sediments contain heavy metals. This chemical hazard can be assessed by evaluating the mobility and speciation of metals after sediment deposition. In this study, the speciation of Zn in the coarse (500 to 2000 μm) and fine (<2 μm) fractions of a contaminated sediment dredged from a ship canal in northern France and deposited on an agricultural soil was determined by physical analytical techniques on raw and chemically treated samples. Zn partitioning between coexisting mineral phases and its chemical associations were first determined by micro-particle-induced X-ray emission and micro-synchrotron-based X-ray radiation fluorescence. Zn-containing mineral species were then identified by X-ray diffraction and powder and polarized extended X-ray absorption fine structure spectroscopy (EXAFS). The number, nature, and proportion of Zn species were obtained by a coupled principal component analysis (PCA) and least squares fitting (LSF) procedure, applied herein for the first time to qualitatively (number and nature of species) and quantitatively (relative proportion of species) speciate a metal in a natural system. The coarse fraction consists of slag grains originating from nearby Zn smelters. In this fraction, Zn is primarily present as sphalerite (ZnS) and to a lesser extent as willemite (Zn 2SiO 4), Zn-containing ferric (oxyhydr)oxides, and zincite (ZnO). In the fine fraction, ZnS and Zn-containing Fe (oxyhydr)oxides are the major forms, and Zn-containing phyllosilicate is the minor species. Weathering of ZnS, Zn 2SiO 4, and ZnO under oxidizing conditions after the sediment disposal accounts for the uptake of Zn by Fe (oxyhydr)oxides and phyllosilicates. Two geochemical processes can explain the retention of Zn by secondary minerals: uptake on preexisting minerals and precipitation with dissolved Fe and Si. The second process likely occurs because dissolved Zn and Si are supersaturated with respect to Zn phyllosilicate. EXAFS spectroscopy, in combination with PCA and LSF, is shown to be a meaningful approach to quantitatively determining the speciation of trace elements in sediments and soils.

Corrigendum to "Chemical speciation of trace metals emitted from Indonesian peat fires for health risk assessment" [Atmos. Res. 122 (2013) 571-578

NASA Astrophysics Data System (ADS)

Betha, Raghu; Pradani, Maharani; Lestari, Puji; Joshi, Umid Man; Reid, Jeffrey S.; Balasubramanian, Rajasekhar

2018-06-01

The authors regret that inadvertent errors occurred in the estimation of excess life time cancer risk (ELCR) in the above-referenced published paper due to an oversight. Specifically, the slope factor of nickel (Ni) we used in the ELCR calculation should have been 8.4 × 10-1 mg-1 kg day instead of 8.4 × 101 (mg-1 kg day). Further, to be consistent with other publications where we assumed the measured chromium (Cr) to exist entirely as hexavalent chromium (Cr(VI)), we revised the slope factor of Cr to the USEPA recommended value of 42 and recalculated the ELCR accordingly. These revised slope factors do not affect, or influence our overall qualitative conclusion made earlier in the published paper in that people in the immediate vicinity of peat fires are likely to experience severe health problems due to prolonged exposure to high concentrations of trace metals in the peat smoke. The revised ELCR estimates are given below in Table 3.

Heavy metal speciation and risk assessment in dry land and paddy soils near mining areas at Southern China.

PubMed

Liu, Guannan; Wang, Juan; Zhang, Erxi; Hou, Jing; Liu, Xinhui

2016-05-01

Heavy metal contamination of soils has been a long-standing environmental problem in many parts of the world, and poses enormous threats to ecosystem and human health. Speciation of heavy metals in soils is crucial to assessing environmental risks from contaminated soils. In this study, total concentrations and speciation of As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn were measured for agricultural soils near mines along the Diaojiang River in Guangxi Zhuang Autonomy Region, China. The sources of heavy metals in soils also were identified to assess their effect on speciation distribution of soil heavy metals. Furthermore, the speciation distribution of Cd and Zn, main soil heavy metal pollutants, in dry land and paddy soils were compared. Results showed that there were two severely polluted regions near mine area reaching alarming pollution level. As, Cd, Pb, and Zn were more affected by mining activities, showing very strong pollution level in soils. The mean percentage of exchangeable and carbonate fraction was highest and up to 46.8 % for Cd, indicating a high environmental risk. Greater bioavailable fractions of As, Cd, Cu, Mn, Pb, and Zn were found in soils heavily polluted by mining activities, whereas Cr and Ni as geogenic elements in the stable residual fraction. In addition, in the dry land soils, reducible fraction proportion of Cd was higher than that in the paddy soils, whereas exchangeable and carbonate fraction of Cd was lower than that in the paddy soils. Oxidizable fraction of Zn was higher in the paddy soils than that in the dry land soils. The results indicate that the sources of soil heavy metals and land types affect heavy metal speciation in the soil and are significant for environmental risk assessment of soil heavy metal pollutions.

Trace metals in the Ob and Yenisei Rivers' Estuaries (the Kara Sea).

NASA Astrophysics Data System (ADS)

Demina, L. L.

2014-12-01

Behavior of some trace metals (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni and Pb) in water column (soluble <0.45 µm and particulate fractions) and bottom sediments (surface and cores) along the two transects from the Ob River and Yenisei River Estuaries to the Kara Sea was studied. The length of both transects was about 700 km. Water depth was 12-63 m, O2 dissolved :5.36-9.55 ml l-1. Along the transects salinity increased from 0.07 to 34.2 psu, while the SPM' concentration decreased from 10.31 to 0.31 mg/l. Total suspended particulate matter load is more than one order of magnitude higher in the Ob River Estuary comparing to that of the Yenisei River. It has led to a significant difference between the suspended trace metals' concentrations (µg/l) in water of the two estuaries. With salinity increase along transects Fe susp., Mn susp. and Zn susp. decreased by a factor of 100-500, that has led to a growth of a relative portion of dissolved trace metals followed by their bioaccumulation (Demina et al., 2010). A strong direct correlation between suspended Cu, Fe and SPM mass concentration was found. For the first time along the Yenisei River' Estuary -the Kara Sea transect a direct positive correlation between Cu suspended and volume concentration of SPM (mg/ml3) was found, that was attributed to contribution of phytoplankton aggregates in the SPM composition. A trend of relationship between content of suspended As and pelitic fraction (2-10 µm) of SPM was firstly found in theses basins also. Study of trace metal speciation in the bottom sediments (adsorbed, associated with Fe-Mn (oxyhydr)oxides, organic matter and fixed in the mineral lattice or refractory) has revealed the refractory fraction to be prevailing (70-95% total content) for Fe, Zn, Cu, Co, Ni, Cr, Cd and Pb. That means that toxic heavy metals were not available for bottom fauna. Mn was predominantly found in the adsorbed and (oxyhydr)oxides geochemically labile forms, reflecting the redox condition change along both transects and within the sedimentary cores. References. Demina L.L., Gordeev V.V., Galkin S.V., Kravchishina M.D. Biogeochemistry of some heavy metals and metalloids along the transect the Ob River Estuary - the Kara Sea. Oceanology, 2010, vo. 50, No 5, pp. 729- 742.

Assessing the influence of compost and biochar amendments on the mobility and toxicity of metals and arsenic in a naturally contaminated mine soil.

PubMed

Beesley, Luke; Inneh, Onyeka S; Norton, Gareth J; Moreno-Jimenez, Eduardo; Pardo, Tania; Clemente, Rafael; Dawson, Julian J C

2014-03-01

Amending contaminated soils with organic wastes can influence trace element mobility and toxicity. Soluble concentrations of metals and arsenic were measured in pore water and aqueous soil extracts following the amendment of a heavily contaminated mine soil with compost and biochar (10% v:v) in a pot experiment. Speciation modelling and toxicity assays (Vibrio fischeri luminescence inhibition and Lolium perenne germination) were performed to discriminate mechanisms controlling metal mobility and assess toxicity risk thereafter. Biochar reduced free metal concentrations furthest but dissolved organic carbon primarily controlled metal mobility after compost amendment. Individually, both amendments induced considerable solubilisation of arsenic to pore water (>2500 μg l(-1)) related to pH and soluble phosphate but combining amendments most effectively reduced toxicity due to simultaneous reductions in extractable metals and increases in soluble nutrients (P). Thus the measure-monitor-model approach taken determined that combining the amendments was most effective at mitigating attendant toxicity risk. Copyright © 2013 Elsevier Ltd. All rights reserved.

Metal speciation in agricultural soils adjacent to the Irankuh Pb-Zn mining area, central Iran

NASA Astrophysics Data System (ADS)

Mokhtari, Ahmad Reza; Roshani Rodsari, Parisa; Cohen, David R.; Emami, Adel; Dehghanzadeh Bafghi, Ali Akbar; Khodaian Ghegeni, Ziba

2015-01-01

Mining activities are a significant potential source of metal contamination of soils in surrounding areas, with particular concern for metals dispersed into agricultural area in forms that are bioavailable and which may affect human health. Soils in agricultural land adjacent to Pb-Zn mining operations in the southern part of the Irankuh Mountains contain elevated concentrations for a range of metals associated with the mineralization (including Pb, Zn and As). Total and partial geochemical extraction data from a suite of 137 soil samples is used to establish mineralogical controls on ore-related trace elements and help differentiate spatial patterns that can be related to the effects of mining on the agricultural land soils from general geological and environmental controls. Whereas the patterns for Pb, Zn and As are spatially related to the mining operations they display little correlation with the distribution of secondary Fe + Mn oxyhydroxides or carbonates, suggesting dispersion as dust and in forms with limited bioavailability.

Physiological impacts of soil pollution and arsenic uptake in three plant species: Agrostis capillaris, Solanum nigrum and Vicia faba.

PubMed

Austruy, A; Wanat, N; Moussard, C; Vernay, P; Joussein, E; Ledoigt, G; Hitmi, A

2013-04-01

In order to revegetate an industrial soil polluted by trace metals and metalloids (As, Pb, Cu, Cd, Sb), the impact of pollution on three plant species, Solanum nigrum and Agrostis capillaris, both native species in an industrial site, and Vicia faba, a plant model species, is studied. Following the study of soil pollution from the industrial wasteland of Auzon, it appears that the As is the principal pollutant. Particular attention is given to this metalloid, both in its content and its speciation in the soil that the level of its accumulation in plants. In V. faba and A. capillaris, the trace metals and metalloids inhibit the biomass production and involve a lipid peroxidation in the leaves. Furthermore, these pollutants cause a photosynthesis perturbation by stomatal limitations and a dysfunction of photosystem II. Whatever the plant, the As content is less than 0.1 percent of dry matter, the majority of As absorbed is stored in the roots which play the role of trap organ. In parallel, the culture of S. nigrum decreases significantly the exchangeable and weakly adsorbed fraction of As in rhizospheric soil. This study has highlighted the ability of tolerance to trace metals of S. nigrum and to a lesser extent A. capillaris. Our data indicate that V. faba is not tolerant to soil pollution and is not a metallophyte species. Copyright © 2012 Elsevier Inc. All rights reserved.

Changes in heavy metal bioavailability and speciation from a Pb-Zn mining soil amended with biochars from co-pyrolysis of rice straw and swine manure.

PubMed

Meng, Jun; Tao, Mengming; Wang, Lili; Liu, Xingmei; Xu, Jianming

2018-08-15

Biochar has been utilized as a good amendment to immobilize heavy metals in contaminated soils. However, the effectiveness of biochar in metal immobilization depends on biochar properties and metal species. In this study, the biochars produced from co-pyrolysis of rice straw with swine manure at 400°C were investigated to evaluate their effects on bioavailability and chemical speciation of four heavy metals (Cd, Cu, Pb and Zn) in a Pb-Zn contaminated soil through incubation experiment. Results showed that co-pyrolysis process significantly change the yield, ash content, pH, and electrical conductivity (EC) of the blended biochars compared with the single straw/manure biochar. The addition of these biochars significantly increased the soil pH, EC, and dissolved organic carbon (DOC) concentrations. The addition of biochars at a rate of 3% significantly reduced the CaCl 2 -extractable metal concentrations in the order of Pb>Cu>Zn>Cd. The exchangeable heavy metals decreased in all the biochar-amended soils whereas the carbonate-bound metal speciation increased. The increase in soil pH and the decrease in the CaCl 2 extractable metals indicated that these amendments can directly transform the highly availability metal speciation to the stable speciation in soils. In conclusion, biochar derived from co-pyrolysis of rice straw with swine manure at a mass ratio of 3:1 could most effectively immobilize the heavy metals in the soil. Copyright © 2018 Elsevier B.V. All rights reserved.

Migration and speciation of heavy metal in salinized mine tailings affected by iron mining.

PubMed

Zhang, Xu; Yang, Huanhuan; Cui, Zhaojie

2017-10-01

The negative effects of heavy metals have aroused much attention due to their high toxicity to human beings. Migration and transformation trend of heavy metals have a close relationship with soil safety. Researching on migration and transformation of heavy metals in tailings can provide a reliable basis for pollution management and ecosystem restoration. Heavy metal speciation plays an important role in risk assessment. We chose Anshan tailings for our study, including field investigations and laboratory research. Four typical heavy metal elements of mine tailings {Fe (373.89 g/kg), Mn (2,303.80 mg/kg), Pb (40.99 mg/kg) and Cr (199.92 mg/kg)} were studied via Tessier test in vertical and horizontal direction. The main speciation of heavy metals in Anshan tailings was the residual. However, heavy metals have a strong ability for migration and transformation in vertical and horizontal directions. Its tendency to change from stable to unstable speciation results in increasing bioavailability and potential bioavailability. Fe, Mn, Pb and Cr showed different ability in the migration and transformation process (Mn > Pb > Fe > Cr) depending on the characteristics of heavy metals and physicochemical properties of the environment.

Suspended particulate matter determines physical speciation of Fe, Mn, and trace metals in surface waters of Loire watershed.

PubMed

Baalousha, Mohamed; Stoll, Serge; Motelica-Heino, Mikaël; Guigues, Nathalie; Braibant, Gilles; Huneau, Frédéric; Le Coustumer, Philippe

2018-02-10

This study investigates the spatiotemporal variability of major and trace elements, dissolved organic carbon (DOC), total dissolved solids (TDS), and suspended particulate matter (SPM) in surface waters of several hydrosystems of the Loire River watershed in France. In particular, this study aims to delineate the impact of the abovementioned water physicochemical parameters on natural iron and manganese physical speciation (homoaggregation/heteroaggregation) among fine colloidal and dissolved (< 10 nm), colloidal (10-450 nm) and particulate (> 450 nm) phases in Loire River watershed. Results show that the chemistry of the Loire River watershed is controlled by two end members: magmatic and metamorphic petrographic context on the upper part of the watershed; and sedimentary rocks for the middle and low part of the Loire. The percentage of particulate Fe and Mn increased downstream concurrent with the increase in SPM and major cations concentration, whereas the percentage of colloidal Fe and Mn decreased downstream. Transmission electron microscopy analyses of the colloidal and particulate fractions (from the non-filtered water sample) revealed that heteroaggregation of Fe and Mn rich natural nanoparticles and natural organic matter to the particulate phase is the dominant mechanism. The heteroaggregation controls the partitioning of Fe and Mn in the different fractions, potentially due to the increase in the ionic strength, and divalent cations concentration downstream, and SPM concentration. These findings imply that SPM concentration plays an important role in controlling the fate and behavior of Fe and Mn in various sized fractions. Graphical abstract Physical speciation by heteroaggregation of (Fe-Mn) compounds: high [SPM] → [Fe-Mn] particulate faction; low {SPM] → [Fe-Mn] colloid-dissolved fraction.

Biosensor for metal analysis and speciation

DOEpatents

Aiken, Abigail M.; Peyton, Brent M.; Apel, William A.; Petersen, James N.

2007-01-30

A biosensor for metal analysis and speciation is disclosed. The biosensor comprises an electron carrier immobilized to a surface of an electrode and a layer of an immobilized enzyme adjacent to the electrode. The immobilized enzyme comprises an enzyme having biological activity inhibited by a metal to be detected by the biosensor.

Change of heavy metal speciation, mobility, bioavailability, and ecological risk during potassium ferrate treatment of waste-activated sludge.

PubMed

Yu, Ming; Zhang, Jian; Tian, Yu

2018-05-01

The effects of potassium ferrate treatment on the heavy metal concentrations, speciation, mobility, bioavailability, and environmental risk in waste-activated sludge (WAS) at various dosages of potassium ferrate and different treatment times were investigated. Results showed that the total concentrations of all metals (except Cd) were decreased slightly after treatment and the order of metal concentrations in WAS and treated waste-activated sludge (TWAS) was Mg > Zn > Cu > Cr > Pb > Ni > Cd. Most heavy metals in WAS remained in TWAS after potassium ferrate treatment with metal residual rates over 67.8% in TWAS. The distribution of metal speciation in WAS was affected by potassium ferrate treatment. The bioavailability and the mobility of heavy metals (except Mg) in TWAS were mitigated, compared to those in WAS. Meanwhile, the environmental risk of heavy metals (except Pb and Cu) was alleviated after potassium ferrate treatment.

Source and distribution of sedimentary thallium in the Bohai Sea: Implications for hydrodynamic forces and anthropogenic impact

NASA Astrophysics Data System (ADS)

Hu, Ningjing; Liu, Jihua; Shi, Xuefa

2015-04-01

Source and distribution of sedimentary thallium in the Bohai Sea: Implications for hydrodynamic forces and anthropogenic impact Hu Ningjing, Liu Jihua, Shi Xuefa First Institute of Oceanography, State Oceanic Administration, Qingdao 266061, China Thallium (Tl), a non-essential and highly toxic trace metal, is listed as priority toxic pollutant by the United States Environmental Protection Agency (USEPA) (Keith and Telliard, 1979). However, its geochemical cycling in aquatic environment has received far less attention than that of many other trace metals. This has been attributed to relatively little commercial interest in Tl and, until recently, problems inherent in its detection at environmental concentrations (Meeravali and Jiang, 2008). In this study, we investigated the sources, distribution and fate of Tl in surface sediments of the Bohai Sea (BS), China, based on the datasets of total Tl and chemical speciation of Tl of 408 surface sediment samples in the total entire BS. The enrichment factors and chemical speciation of Tl indicated that Tl in BS was dominated by natural Tl, although anthropogenic Tl contamination was observed in the Liuguhe River mouth; the mud deposits are the sinks of Tl and the regional currents and tide systems play a key role on the accumulation of Tl in BS. The distribution of Tl consistent with that of MnO and Fe2O3 as well as the level of Fe-Mn fraction is relatively high, indicating MnO and Fe2O3 influence the geochemical behaviors of Tl in the BS. Although the positive correlation between Tl and TOC is observed for the samples in the BS, however, level of Tl in oxidizable faction could be neglected, suggesting TOC might not be a major factor affecting the concentration of Tl in BS. The low proportion of Tl in the non-residual fraction dominated by the Fe-Mn oxides suggested that the labile Tl was controlled by the Fe-Mn oxides and Tl has a low bioavailability and a minor potential threat to biota in BS. Acknowledgements: this work was jointly supported by National Natural Science Foundation of China (Grant Nos.41076032, 41276052 and 41376073) and the State Oceanic Administration, China (Grant No. 201105003). References Keith, L.H., Telliard, W.A., 1979. Priority pollutants-A perspective view. Environmental Science and Technology 13, 416-423. Meeravali, N.M., Jiang, S.-J., 2008. Ultra-trace speciation analysis of thallium in environmental water samples by inductively coupled plasma mass spectrometry after a novel sequential mixed-micelle cloud point extraction. Journal of Analytical Atomic Spectrometry 23, 555-560.

Dispersion, Speciation, and Pollution Assessment of Heavy Metals Pb and Zn in Surface Sediment from Disturbed Ecosystem of Jeneberang Waters

NASA Astrophysics Data System (ADS)

Najamuddin; Surahman

2017-10-01

Surface sediments were collected from seventeen stations in Jeneberang waters (riverine, estuarine, and marine). Lead (Pb) and zinc (Zn) concentrations were determined by atomic absorption spectrometry, and the speciation of metals was obtained by a sequential extraction procedure. Dispersion of Pb and Zn were found higher in the riverine and marine samples than the estuarine samples. Following speciation, the metals were found similar composition of fraction in the riverine and estuarine samples but any different in the marine samples. The results indicated that there is a change of dispersion pattern and speciation composition of metals due to the presence of the dam that lies at the boundary between the estuary and the river. The toxicity unit was indicated low toxicity level; pollution level was in weakly to moderately polluted while the aquatic environment risk attributed were no risky to light risk.

Lead Speciation And Bioavailability In Apatite-Amended Sediments

EPA Science Inventory

The in situ sequestration of lead (Pb) in sediment with a phosphate amendment was investigated by Pb speciation and bioavailability. Sediment Pb in preamendment samples was identified as galena (PbS) with trace amounts of absorbed Pb. Sediment exposed to atmospheric conditions ...

Influence of Organic Matter - Mineral Interfacial Reactions on Metal(loid) Speciation and Bioaccessibility

NASA Astrophysics Data System (ADS)

Chorover, J.; Kong, S.; Root, R. A.; Thomas, A.

2015-12-01

Bioaccessibility of contaminant metals in geomedia is often measured on the basis of kinetic release to solution during in vitro reaction with biofluid simulants. We postulate that development of a predictive-mechanistic understanding of bioaccessibility requires knowledge of metal(loid) molecular speciation upon sample introduction, as well as its change over the course of the in vitro reaction. Our results - including data from batch, column, mesocosm and field studies pertaining to arsenic, lead, and zinc contaminated materials - indicate the strong influence of organic matter and associated biological activity on metal(loid) speciation in mine tailings and related model systems. Furthermore, presence/absence of organic matter during bioassays affects the kinetics of metal(loid) release into biofluid simulants through multiple mechanisms.

In Situ Distribution and Speciation of Toxic Copper, Nickel, and Zinc in Hydrated Roots of Cowpea1[W][OA

PubMed Central

Kopittke, Peter M.; Menzies, Neal W.; de Jonge, Martin D.; McKenna, Brigid A.; Donner, Erica; Webb, Richard I.; Paterson, David J.; Howard, Daryl L.; Ryan, Chris G.; Glover, Chris J.; Scheckel, Kirk G.; Lombi, Enzo

2011-01-01

The phytotoxicity of trace metals is of global concern due to contamination of the landscape by human activities. Using synchrotron-based x-ray fluorescence microscopy and x-ray absorption spectroscopy, the distribution and speciation of copper (Cu), nickel (Ni), and zinc (Zn) was examined in situ using hydrated roots of cowpea (Vigna unguiculata) exposed to 1.5 μm Cu, 5 μm Ni, or 40 μm Zn for 1 to 24 h. After 24 h of exposure, most Cu was bound to polygalacturonic acid of the rhizodermis and outer cortex, suggesting that binding of Cu to walls of cells in the rhizodermis possibly contributes to the toxic effects of Cu. When exposed to Zn, cortical concentrations remained comparatively low with much of the Zn accumulating in the meristematic region and moving into the stele; approximately 60% to 85% of the total Zn stored as Zn phytate within 3 h of exposure. While Ni concentrations were high in both the cortex and meristem, concentrations in the stele were comparatively low. To our knowledge, this is the first report of the in situ distribution and speciation of Cu, Ni, and Zn in hydrated (and fresh) plant tissues, providing valuable information on the potential mechanisms by which they are toxic. PMID:21525332

Comparison of metallothionein concentrations and tissue distribution of trace metals in crabs (Pachygrapsus marmoratus) from a metal-rich estuary, in and out of the reproductive season.

PubMed

Mouneyrac, C; Amiard-Triquet, C; Amiard, J C; Rainbow, P S

2001-07-01

Crabs, Pachygrapsus marmoratus, were sampled in June 1997 and February 1998 from two sites (at the mouth and 25 km upstream) in the metal-rich Gironde estuary, France. Gills and hepatopancreas were analysed for metal (Cd, Cu, Zn) and metallothionein (MT) contents, in order to examine the influence of both biological and environmental factors on the physico-chemical forms of detoxified metal storage in the crabs. The concentrations of MT and both cytosolic and insoluble metals were not greatly different between males and females, and the influence of organ weights was also minimal. Intersite differences were observed, probably resulting from the gradient of salinity in the estuary, which interacts with both the chemical speciation and bioavailability of metals, and the general protein metabolism of the crabs. Seasonal changes were also important, probably in interaction with the moult and reproductive cycles. In February, concentrations of insoluble metals were generally higher than in June, in both organs, suggesting that essential metals, particularly Zn, are stored during winter then remobilised during the breeding season. The natural variability in the concentrations of MT often concealed any relationship with accumulated metal concentrations. Thus MT in crabs cannot be considered as a useful biomarker of metal pollution.

Analytical methods for determination of free metal ion concentration, labile species fraction and metal complexation capacity of environmental waters: a review.

PubMed

Pesavento, Maria; Alberti, Giancarla; Biesuz, Raffaela

2009-01-12

Different experimental approaches have been suggested in the last few decades to determine metal species in complex matrices of unknown composition as environmental waters. The methods are mainly focused on the determination of single species or groups of species. The more recent developments in trace elements speciation are reviewed focusing on methods for labile and free metal determination. Electrochemical procedures with low detection limit as anodic stripping voltammetry (ASV) and the competing ligand exchange with adsorption cathodic stripping voltammetry (CLE-AdCSV) have been widely employed in metal distribution studies in natural waters. Other electrochemical methods such as stripping chronopotentiometry and AGNES seem to be promising to evaluate the free metal concentration at the low levels of environmental samples. Separation techniques based on ion exchange (IE) and complexing resins (CR), and micro separation methods as the Donnan membrane technique (DMT), diffusive gradients in thin-film gels (DGT) and the permeation liquid membrane (PLM), are among the non-electrochemical methods largely used in this field and reviewed in the text. Under appropriate conditions such techniques make possible the evaluation of free metal ion concentration.

[The progress in speciation analysis of trace elements by atomic spectrometry].

PubMed

Wang, Zeng-Huan; Wang, Xu-Nuo; Ke, Chang-Liang; Lin, Qin

2013-12-01

The main purpose of the present work is to review the different non-chromatographic methods for the speciation analysis of trace elements in geological, environmental, biological and medical areas. In this paper, the sample processing methods in speciation analysis were summarized, and the main strategies for non-chromatographic technique were evaluated. The basic principles of the liquid extractions proposed in the published literatures recently and their advantages and disadvantages were discussed, such as conventional solvent extraction, cloud point extraction, single droplet microextraction, and dispersive liquid-liquid microextraction. Solid phase extraction, as a non-chromatographic technique for speciation analysis, can be used in batch or in flow detection, and especially suitable for the online connection to atomic spectrometric detector. The developments and applications of sorbent materials filled in the columns of solid phase extraction were reviewed. The sorbents include chelating resins, nanometer materials, molecular and ion imprinted materials, and bio-sorbents. Other techniques, e. g. hydride generation technique and coprecipitation, were also reviewed together with their main applications.

Fate of heavy metals during municipal solid waste incineration.

PubMed

Abanades, S; Flamant, G; Gagnepain, B; Gauthier, D

2002-02-01

A thermodynamic analysis was performed to determine whether it is suitable to predict the heavy metal (HM) speciation during the Municipal Solid Waste Incineration process. The fate of several selected metals (Cd, Pb, Zn, Cr, Hg, As, Cu, Co, Ni) during incineration was theoretically investigated. The equilibrium analysis predicted the metal partitioning during incineration and determined the impact of operating conditions (temperature and gas composition) on their speciation. The study of the gas composition influence was based on the effects of the contents of oxygen (reducing or oxidising conditions) and chlorine on the HM partitioning. The theoretical HM speciation which was calculated in a complex system representing a burning sample of Municipal Solid Waste can explain the real partitioning (obtained from literature results) of all metals among the various ashes except for Pb. Then, the results of the thermodynamic study were compared with those of characterisation of real incinerator residues, using complementary techniques (chemical extraction series and X-ray micro-analyses). These analysis were performed to determine experimentally the speciation of the three representative metals Cr, Pb, and Zn. The agreement is good for Cr and Zn but not for Pb again, which mainly shows unleachable chemical speciations in the residues. Pb tends to remain in the bottom ash whereas thermodynamics often predicts its complete volatilisation under chlorides, and thus its presence exclusively in fly ash.

Including the spatial variability of metal speciation in the effect factor in life cycle impact assessment: Limits of the equilibrium partitioning method.

PubMed

Tromson, Clara; Bulle, Cécile; Deschênes, Louise

2017-03-01

In life cycle assessment (LCA), the potential terrestrial ecotoxicity effect of metals, calculated as the effect factor (EF), is usually extrapolated from aquatic ecotoxicological data using the equilibrium partitioning method (EqP) as it is more readily available than terrestrial data. However, when following the AMI recommendations (i.e. with at least enough species that represents three different phyla), there are not enough terrestrial data for which soil properties or metal speciation during ecotoxicological testing are specified to account for the influence of soil property variations on metal speciation when using this approach. Alternatively, the TBLM (Terrestrial Biotic Ligand Model) has been used to determine an EF that accounts for speciation, but is not available for metals; hence it cannot be consistently applied to metals in an LCA context. This paper proposes an approach to include metal speciation by regionalizing the EqP method for Cu, Ni and Zn with a geochemical speciation model (the Windermere Humic Aqueous Model 7.0), for 5213 soils selected from the Harmonized World Soil Database. Results obtained by this approach (EF EqP regionalized ) are compared to the EFs calculated with the conventional EqP method, to the EFs based on available terrestrial data and to the EFs calculated with the TBLM (EF TBLM regionalized ) when available. The spatial variability contribution of the EF to the overall spatial variability of the characterization factor (CF) has been analyzed. It was found that the EFs EqP regionalized show a significant spatial variability. The EFs calculated with the two non-regionalized methods (EqP and terrestrial data) fall within the range of the EFs EqP regionalized . The EFs TBLM regionalized cover a larger range of values than the EFs EqP regionalized but the two methods are not correlated. This paper highlights the importance of including speciation into the terrestrial EF and shows that using the regionalized EqP approach is not an acceptable proxy for terrestrial ecotoxicological data even if it can be applied to all metals. Copyright © 2016. Published by Elsevier B.V.

Metal Speciation in Landfill Leachates with a Focus on the Influence of Organic Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

F Claret; C Tournassat; C Crouzet

This study characterizes the heavy-metal content in leachates collected from eight landfills in France. In order to identify heavy metal occurrence in the different size fractions of leachates, a cascade filtration protocol was applied directly in the field, under a nitrogen gas atmosphere to avoid metal oxidation. The results of analyses performed on the leachates suggest that most of the metals are concentrated in the <30 kDa fraction, while lead, copper and cadmium show an association with larger particles. Initial speciation calculations, without considering metal association with organic matter, suggest that leachate concentrations in lead, copper, nickel and zinc aremore » super-saturated with respect to sulphur phases. Speciation calculations that account for metal complexation with organic matter, considered as fulvic acids based on C1(s) NEXAFS spectroscopy, show that this mechanism is not sufficient to explain such deviation from equilibrium conditions. It is therefore hypothesized that the deviation results also from the influence of biological activity on the kinetics of mineral phase precipitation and dissolution, thus providing a dynamic system. The results of chemical analyses of sampled fluids are compared with speciation calculations and some implications for the assessment of metal mobility and natural attenuation in a context of landfill risk assessment are discussed.« less

VARIATION OF ELEMENT SPECIATION IN COAL COMBUSTION AEROSOLS WITH PARTICLE SIZE

EPA Science Inventory

The speciation of sulfur, iron and key trace elements (Cr, As, Se, Zn) in combustion ash aerosols has been examined as a function of size from experimental combustion units burning Utah and Illinois bituminous coals. Although predominantly present as sulfate, sulfur was also pre...

Biodegradation and speciation of residual SS-ethylenediaminedisuccinic acid (EDDS) in soil solution left after soil washing.

PubMed

Tandy, Susan; Ammann, Adrian; Schulin, Rainer; Nowack, Bernd

2006-07-01

This paper aims to investigate the degradation and speciation of EDDS-complexes (SS-ethylenediaminedisuccinic acid) in soil following soil washing. The changes in soil solution metal and EDDS concentrations were investigated for three polluted soils. EDDS was degraded after a lag phase of 7-11 days with a half-life of 4.18-5.60 days. No influence of EDDS-speciation on the reaction was observed. The decrease in EDDS resulted in a corresponding decrease in solubilized metals. Changes in EDDS speciation can be related to (1) initial composition of the soil, (2) temporarily anoxic conditions in the soil slurry after soil washing, (3) exchange of EDDS complexes with Cu even in soils without elevated Cu and (4) formation of NiEDDS. Dissolved organic matter is important for metal speciation at low EDDS concentrations. Our results show that even in polluted soils EDDS is degraded from a level of several hundred micromoles to below 1 microM within 50 days.

Nickel speciation in several serpentine (ultramafic) topsoils via bulk synchrotron-based techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siebecker, Matthew G.; Chaney, Rufus L.; Sparks, Donald L.

2017-07-01

Serpentine soils have elevated concentrations of trace metals including nickel, cobalt, and chromium compared to non-serpentine soils. Identifying the nickel bearing minerals allows for prediction of potential mobility of nickel. Synchrotron-based techniques can identify the solid-phase chemical forms of nickel with minimal sample treatment. Element concentrations are known to vary among soil particle sizes in serpentine soils. Sonication is a useful method to physically disperse sand, silt and clay particles in soils. Synchrotron-based techniques and sonication were employed to identify nickel species in discrete particle size fractions in several serpentine (ultramafic) topsoils to better understand solid-phase nickel geochemistry. Nickel commonlymore » resided in primary serpentine parent material such as layered-phyllosilicate and chain-inosilicate minerals and was associated with iron oxides. In the clay fractions, nickel was associated with iron oxides and primary serpentine minerals, such as lizardite. Linear combination fitting (LCF) was used to characterize nickel species. Total metal concentration did not correlate with nickel speciation and is not an indicator of the major nickel species in the soil. Differences in soil texture were related to different nickel speciation for several particle size fractionated samples. A discussion on LCF illustrates the importance of choosing standards based not only on statistical methods such as Target Transformation but also on sample mineralogy and particle size. Results from the F-test (Hamilton test), which is an underutilized tool in the literature for LCF in soils, highlight its usefulness to determine the appropriate number of standards to for LCF. EXAFS shell fitting illustrates that destructive interference commonly found for light and heavy elements in layered double hydroxides and in phyllosilicates also can occur in inosilicate minerals, causing similar structural features and leading to false positive results in LCF.« less

Characterizing Zinc Speciation in Soils from a Smelter-Affected Boreal Forest Ecosystem.

PubMed

Hamilton, Jordan G; Farrell, Richard E; Chen, Ning; Feng, Renfei; Reid, Joel; Peak, Derek

2016-03-01

HudBay Minerals, Inc., has mined and/or processed Zn and Cu ore in Flin Flon, MB, Canada, since the 1930s. The boreal forest ecosystem and soil surrounding these facilities have been severely impacted by mixed metal contamination and HSO deposition. Zinc is one of the most prevalent smelter-derived contaminants and has been identified as a key factor that may be limiting revegetation. Metal toxicity is related to both total concentrations and speciation; therefore, X-ray absorption spectroscopy and X-ray fluorescence mapping were used to characterize Zn speciation in soils throughout the most heavily contaminated areas of the landscape. Zinc speciation was linked to two distinct soil types. Group I soils consist of exposed soils in weathered positions of bedrock outcrops with Zn present primarily as franklinite, a (ZnFeO) spinel mineral. Group II soils are stabilized by an invasive metal-tolerant grass species, with Zn found as a mixture of octahedral (Fe oxides) and tetrahedral Mn oxides) adsorption complexes with a franklinite component. Soil erosion influences Zn speciation through the redistribution of Zn and soil particulates from Group I landscape positions to Group II soils. Despite Group II soils having the highest concentrations of CaCl-extractable Zn, they support metal-tolerant plant growth. The metal-tolerant plants are probably preferentially colonizing these areas due to better soil and nutrient conditions as a result of soil deposition from upslope Group I areas. Zinc concentration and speciation appears to not influence the colonization by metal-tolerant grasses, but the overall soil properties and erosion effects prevent the revegetation by native boreal forest species. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Intracellular And Subcellular Partitioning Of Nickel In Aureococcus Anophagefferens

NASA Astrophysics Data System (ADS)

Wang, B.; Axe, L.; Wei, L.; Bagheri, S.; Michalopoulou, Z.

2008-12-01

Brown tides are caused by Aureococcus anophagefferens, a species of Pelagophyceae, and have been observed in NY/NJ waterways effecting ecosystems by attenuating light, changing water color, reducing eelgrass beds, decreasing shellfisheries, and further impacting the food web by reducing phytoplankton. Although the impact of macronutrients and iron on A. anophagefferens has been well studied, contaminants, and specifically trace metals have not. In long-term experiments designed to investigate the growth and toxicity, Cd, Cu, Ni, and Zn exposure was evaluated over 10-13 to 10-7 M for the free metal ion. While growth was inhibited or terminated from exposure to Cd and Cu, nickel addition ([Ni2+]: 10-11.23 to 10-10.23 M) promoted A. anophagefferens growth. Short-term experiments are being conducted to better understand mechanistically nickel speciation and distribution. Both total intracellular and subcellular metal concentrations are being assessed with radio-labeled 63Ni. Subcellular fractions are defined as metal-sensitive fractions (MSF) constituting organelles, cell debris, and heat-denatured protein [HDP] and biologically detoxified metal comprising heat-stabilized protein [HSP] and metal-rich granules [MRG]. Based on subcellular distribution, aqueous [Ni2+] concentrations, and A. anophagefferens growth rates, potential reaction pathways promoting A. anophagefferens growth can be addressed.

A COMPUTATIONAL AND EXPERIMENTAL STUDY OF MERCURY SPECIATION AS FACILITATED BY THE DEACON PROCESS

EPA Science Inventory

The paper gives results of a computational and experimental study of mercury (Hg) speciation as facilitated by the Deacon process. Fly ashes that contain trace cupric or ferric oxide are effective catalysts for elemental mercury (Hg) conversion to mercuric chloride in the presenc...

Atmospheric mercury and fine particulate matter in coastal New England: implications for mercury and trace element sources in the northeastern United States

USGS Publications Warehouse

Kolker, Allan; Engle, Mark A.; Peucker-Ehrenbrink, Bernhard; Geboy, Nicholas J.; Krabbenhotft, David P.; Bothner, Michael H.; Tate, Michael T.

2013-01-01

Intensive sampling of ambient atmospheric fine particulate matter was conducted at Woods Hole, Massachusetts over a four-month period from 3 April to 29 July, 2008, in conjunction with year-long deployment of the USGS Mobile Mercury Lab. Results were obtained for trace elements in fine particulate matter concurrently with determination of ambient atmospheric mercury speciation and concentrations of ancillary gasses (SO2, NOx, and O3). For particulate matter, trace element enrichment factors greater than 10 relative to crustal background values were found for As, Bi, Cd, Cu, Hg, Pb, Sb, V, and Zn, indicating contribution of these elements by anthropogenic sources. For other elements, enrichments are consistent with natural marine (Na, Ca, Mg, Sr) or crustal (Ba, Ce, Co, Cs, Fe, Ga, La, Rb, Sc, Th, Ti, U, Y) sources, respectively. Positive matrix factorization was used together with concentration weighted air-mass back trajectories to better define element sources and their locations. Our analysis, based on events exhibiting the 10% highest PM2.5 contributions for each source category, identifies coal-fired power stations concentrated in the U.S. Ohio Valley, metal smelting in eastern Canada, and marine and crustal sources showing surprisingly similar back trajectories, at times each sampling Atlantic coastal airsheds. This pattern is consistent with contribution of Saharan dust by a summer maximum at the latitude of Florida and northward transport up the Atlantic Coast by clockwise circulation of the summer Bermuda High. Results for mercury speciation show diurnal production of RGM by photochemical oxidation of Hg° in a marine environment, and periodic traverse of the study area by correlated RGM-SO2(NOx) plumes, indicative of coal combustion sources.

Trace Element Speciation and Distribution Study at Shewanella oneidensis MR-1 Biofilm/Mineral/Water Interfaces

NASA Astrophysics Data System (ADS)

Gelabert, A.; Wang, Y.; Gescher, J.; Ha, J.; Cordova, C. D.; Singer, D. M.; Spormann, A. M.; Trainor, T. P.; Eng, P. J.; Brown, G. E.

2006-12-01

Fe- and Al-(oxyhydr)oxides are among the most reactive mineral surfaces contacted by surface and ground waters, and thus they constitute important sorbents for heavy metal and metalloid ions. As microbial biofilms may be present as coatings on these minerals, they are likely to induce major changes in surface charges and sorption capacities for metal(loid) ions compared to biofilm-free mineral surfaces. In addition, the micro- environments in biofilms can be quite different from those in bulk solutions, which can enhance (or inhibit) metal adsorption on mineral surfaces and produce biominerals that are not predicted by equilibrium thermodynamics based on the bulk solution values. In order to provide a more quantitative understanding of these effects, we have carried out a study of the interaction of Zn(II), Pb(II), and As(V) with Shewanella oneidensis (wild type, EPS-deficient mutant, and ppx- and ppk-deficient mutants) grown on highly polished and oriented single crystal surfaces of α-Al2O3 (1-102) and α-Fe2O3 (0001). This gram-negative bacterium commonly found in soil and sediments can use a wide range of electron donors and terminal electron acceptors including Fe(III) and Mn(IV) oxides under anaerobic conditions. In-situ ATR-FTIR analyses and potentiometric titrations of S. oneidensis biofilm collected from a glass bead-filled column inoculated with S. oneidensis were conducted in order to determine the nature of functional groups present on the bacterial surfaces, to quantify the site densities and protonation constants for these groups, and to determine the electrostatic parameters for S. oneidensis surfaces. GI-XAFS analyses performed on BL 11-2 at SSRL, together with macroscopic metal adsorption experiments as a function of pH (2 to 6.5), metal concentration (10-3 to 10-7 M), and ionic strength (10-1 to 10-3 M), were used to determine ion speciation and local coordination environments in the biofilm and to develop a surface complexation model describing the interactions among biofilm, metal(loid)s, and mineral surfaces. The long-period X-ray Standing Wave- fluorescent yield (XSW-FY) method, performed on BL ID-13-C at the APS, was used to obtain quantitative in situ information on the partitioning of Zn(II), Pb(II), and As(V) at these interfaces as a function of pH and ion concentration. XSW-FY results show that S. oneidensis biofilms do not block reactive sites on the hematite or alumina surfaces under our experimental conditions, which is consistent with the conclusion of our previous studies on trace element distributions at Burkholderia cepacia/mineral/water interfaces. Comparison of the observed trace element partitioning measured by XSW-FY with theoretical predictions of partitioning through thermodynamic models (using binding constants of metal(loid)s with the biofilm determined in this study and published binding constants of metal(loid)s with mineral substrates) allows us to describe biofilm local microenvironments and to understand how the biofilm coatings affect the reactivity of mineral surfaces.

[Speciation and Risk Characteristics of Heavy Metals in the Sediments of the Yangtze Estuary].

PubMed

Yin, Su; Feng, Cheng-hong; Li, Yang-yang; Yin, Li-feng; Shen, Zhen-yao

2016-03-15

Based on the investigation on the distribution of total contents and speciation of 8 heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, Zn) in the surface sediments at 14 typical sites of the Yangtze Estuary during three hydrological seasons ( wet, normal, and dry seasons) , this study applied equilibrium partitioning approach to build the sediment quality guidelines (SQGs) of the Yangtze Estuary, and assessed ecological risks of the heavy metals. The relationship between ecological risk and speciation of heavy metals was also revealed. The results showed that, except for Cd, the residual fraction was the main speciation of heavy metals, especially for As, Cr and Hg, their residual fraction proportions were all over 90%. The sediment quality guidelines of the Yangtze Estuary for As, Cd, Cr, Cu, Hg, Ni, Pb, Zn were 43.29, 0.672, 79.65, 19.08, 0.569, 339.09, 30.87, 411.36 µg · g⁻¹, respectively. Cu had the highest ecological risk to aquatic organisms. The upstream of Yangtze Estuary was mainly affected by Yangtze River runoff, where the risks were relatively high in wet season and relatively low in normal and dry seasons. However, the downstream of the estuary was mainly affected by municipal sewage of cities like Shanghai, where the risks were relatively high, especially in normal and dry seasons. There were three different relationships between the ecological risks and speciation of the eight heavy metals.

Hybrid biosorbents for removal of pollutants and remediation

NASA Astrophysics Data System (ADS)

Burlakovs, Juris; Klavins, Maris; Robalds, Artis; Ansone, Linda

2014-05-01

For remediation of soils and purification of polluted waters, wastewaters, biosorbents might be considered as prospective groups of materials. Amongst them peat have a special role due to low cost, biodegradability, high number of functional groups, well developed surface area and combination of hydrophilic/hydrophobic structural elements. Peat as sorbent have good application potential for removal of trace metals, and we have demonstrated peat sorption capacities, sorption kinetics, thermodynamics in respect to metals with different valencies - Tl(I), Cu(II), Cr(III). However, peat sorption capacity in respect to nonmetallic (anionic species) elements is low. Also peat mechanical properties do not support application in large scale column processes thereby, to expand peat application sphere, the approach of biomass based hybrid sorbents has been elaborated. The concept "hybrid sorbent" in understanding of biosorbent means natural, biomass based modified material, covered with another sorbent material, thus combining properties of both such as sorbent functionalities, surface properties etc. As the "covering layer" both inorganic substances, mineral phases (iron oxohydroxides, oxyappatite) and organic polymers (using graft polymerization) were used. The obtained sorbents were characterised by their spectral properties, surface area and elemental composition. The obtained hybrid sorbents were tested for sorption of compounds in anionic speciation forms, for example of arsenic, antimony, tellurium and phosphorous compounds in comparison with weakly basic anionites. The highest sorption capacity was observed when peat sorbents modified with iron compounds were used. Sorption of different arsenic speciation forms onto iron-modified peat sorbents was investigated as a function of pH and temperature. It was established that sorption capacity increases with a rise in temperature as the calculation of sorption process thermodynamic parameters indicates the spontaneity of sorption process and its endothermic nature. The recycling options of obtained compounds after their saturation with metal or non-metallic species are suggested.

ASSESSING SPECIATION AND RELEASE OF HEAVY METALS FROM COAL COMBUSTION PRODUCTS

EPA Science Inventory

In this study, the speciation of heavy metals such as arsenic, selenium, lead, zinc and mercury in coal combustion products (CCPs) was evaluated using sequential extraction procedures. Coal fly ash, bottom ash and flue gas desulphurization (FGD) sludge samples were used in the ex...

Metal speciation in salt marsh sediments: Influence of halophyte vegetation in salt marshes with different morphology

NASA Astrophysics Data System (ADS)

Pedro, Sílvia; Duarte, Bernardo; Raposo de Almeida, Pedro; Caçador, Isabel

2015-12-01

Salt marshes provide environmental conditions that are known to affect metal speciation in sediments. The elevational gradient along the marsh and consequent differential flooding are some of the major factors influencing halophytic species distribution and coverage due to their differential tolerance to salinity and submersion. Different species, in turn, also have distinct influences on the sediment's metal speciation, and its metal accumulation abilities. The present work aimed to evaluate how different halophyte species in two different salt marshes could influence metal partitioning in the sediment at root depth and how that could differ from bare sediments. Metal speciation in sediments around the roots (rhizosediments) of Halimione portulacoides, Sarcocornia fruticosa and Spartina maritima was determined by sequentially extracting operationally defined fractions with solutions of increasing strength and acidity. Rosário salt marsh generally showed higher concentrations of all metals in the rhizosediments. Metal partitioning was primarily related to the type of metal, with the elements' chemistry overriding the environment's influence on fractionation schemes. The most mobile elements were Cd and Zn, with greater availability being found in non-vegetated sediments. Immobilization in rhizosediments was predominantly influenced by the presence of Fe and Mn oxides, as well as organic complexes. In the more mature of both salt marshes, the differences between vegetated and non-vegetated sediments were more evident regarding S. fruticosa, while in the younger system all halophytes presented significantly different metal partitioning when compared to that of mudflats.

Evaluation of trace metals bioavailability in Japanese river waters using DGT and a chemical equilibrium model.

PubMed

Han, Shuping; Naito, Wataru; Hanai, Yoshimichi; Masunaga, Shigeki

2013-09-15

To develop efficient and effective methods of assessing and managing the risk posed by metals to aquatic life, it is important to determine the effects of water chemistry on the bioavailability of metals in surface water. In this study, we employed the diffusive gradients in thin-films (DGT) to determine the bioavailability of metals (Ni, Cu, Zn, and Pb) in Japanese water systems. The DGT results were compared with a chemical equilibrium model (WHAM 7.0) calculation to examine its robustness and utility to predict dynamic metal speciation. The DGT measurements showed that biologically available fractions of metals in the rivers impacted by mine drainage and metal industries were relatively high compared with those in urban rivers. Comparison between the DGT results and the model calculation indicated good agreement for Zn. The model calculation concentrations for Ni and Cu were higher than the DGT concentrations at most sites. As for Pb, the model calculation depended on whether the precipitated iron(III) hydroxide or precipitated aluminum(III) hydroxide was assumed to have an active surface. Our results suggest that the use of WHAM 7.0 combined with the DGT method can predict bioavailable concentrations of most metals (except for Pb) with reasonable accuracy. Copyright © 2013. Published by Elsevier Ltd.

Isotopic Biomarkers of Nitrogenase Metalloenzymes: Forging Links Between the Cycles of Nitrogen and Trace Metals

NASA Astrophysics Data System (ADS)

Zhang, X.; McRose, D. L.; Darnajoux, R.; Bellenger, J. P.; Kraepiel, A. M. L.

2015-12-01

Biological N2 fixation, catalyzed by the metalloenzyme nitrogenase, is a critical process that makes life possible on Earth. Environmental N2 fixation has been automatically attributed to canonical Mo-based nitrogenases despite over two decades of knowledge that two other metalloenzyme forms of nitrogenase exist: those containing catalytic V or Fe-only. A key area of missing information is the contribution of the "alternative" V and Fe-only nitrogenases, as the interpretation of field data to construct budgets and assess N availability depends on the type of nitrogenase metalloenzyme used to fix N2. Additionally, substantial changes in metal speciation over geological time may have favored the use of different metalloenzymes, with implications for evolution of the biosphere. Despite the potential importance of alternative nitrogenases in modern and ancient N cycling, few methods can determine their contributions to environmental N2 fixation. Here, we present new isotopic methods to distinguish between the activities of Mo, V, and Fe-only nitrogenases. We show evidence for alternative N2 fixation in diverse environments (cyanolichens, microbial mats, sediments, leaf litter), thereby linking a key process in the nitrogen cycle to specific metalloenzyme forms of nitrogenase. The results invite a reexamination of the conditions under which the different nitrogenase metalloenzymes are active and may lead to new insights into the coupling of the cycles of nitrogen and trace metals.

[Analysis and separation of organic and inorganic speciations of soluble zinc in edible flowers].

PubMed

Peng, Shan-shan; Huang, Guo-qing

2005-02-01

Considering the medicinal effects of the edible flowers, the authors studied the separation of trace element zinc's soluble organic and inorganic speciations in water decoction of three edible flowers: Chrysanthemum, Cottonrose hibiscus and Honeysucker by using the 0.45 microm membrane filter and amberlite XAD-2 macroreticular resins. And trace element zinc contents were determined by atomic absorption spectrometry. The optimal conditions for separation had been established. This study verifies the economic value of developing edible flowers, and provides theoretical basis for developing edible flowers as the third functional food materials.

Distribution and speciation of metals (Cu, Zn, Cd, and Pb) in agricultural and non-agricultural soils near a stream upriver from the Pearl River, China.

PubMed

Yang, Silin; Zhou, Dequn; Yu, Huayong; Wei, Rong; Pan, Bo

2013-06-01

The distribution and chemical speciation of typical metals (Cu, Zn, Cd and Pb) in agricultural and non-agricultural soils were investigated in the area of Nanpan River, upstream of the Pearl River. The investigated four metals showed higher concentrations in agricultural soils than in non-agricultural soils, and the site located in factory district contained metals much higher than the other sampling sites. These observations suggested that human activities, such as water irrigation, fertilizer and pesticide applications might have a major impact on the distribution of metals. Metal speciation analysis presented that Cu, Zn and Cd were dominated by the residual fraction, while Pb was dominated by the reducible fraction. Because of the low mobility of the metals in the investigated area, no remarkable difference could be observed between upstream and downstream separated by the factory site. Copyright © 2013 Elsevier Ltd. All rights reserved.

Humic acids decrease uptake and distribution of trace metals, but not the growth of radish exposed to cadmium toxicity.

PubMed

Ondrasek, Gabrijel; Rengel, Zed; Romic, Davor

2018-04-30

Naturally-occurring highly-complexed and polymerised organics such as humic acids (HA), due to their large negative charge, play a crucial role in biogeochemistry of trace metals (TM). Toxic (Cd) as well as essential (Zn, Cu, Mn) TM bind strongly to HA, but how these organo-metalic forms influence metal uptake by plants is poorly understood. A solution culture study was conducted to characterize the effects of different concentrations of HA (0-225mg/L) on the growth and element uptake/distribution in roots, shoots and hypocotyls of radish (Raphanus sativus L.) exposed to Cd (0.5mg/L) contamination. After 10-d-exposure to applied treatments, Cd induced phytotoxicity; in contrast, different concentrations of HA had no influence on biomass, but decreased concentration of most TM in examined tissues (Cu by 4.2-fold, Zn by 2.2-fold, Cd by 1.6-fold and Mn by 34%) and their total plant accumulation (Cu by 73%, Cd by 39%, Zn by 29% and Mn by 22%). HA influenced the transport/distribution of TM, decreasing accumulation in roots and increasing their translocation/deposition in shoots, with no effect on TM content in edible hypocotyls. Chemical speciation modelling of the rooting medium confirmed predominance of free metallic forms in the control (no HA) and the pronounced organo-metal complexation in the HA treatments. The results provide evidence of strong capacity of HA to decrease phytoavailability and uptake of Cd, Zn, Cu and Mn while being non-toxic even at relatively high concentration (225mg/L). Thus, HA, as naturally present soil components, control mobility and phyto-extraction of most TM as well as their phyto-accumulation. Copyright © 2017 Elsevier Inc. All rights reserved.

Application of chemometric analysis and self Organizing Map-Artificial Neural Network as source receptor modeling for metal speciation in river sediment.

PubMed

Pandey, Mayank; Pandey, Ashutosh Kumar; Mishra, Ashutosh; Tripathi, B D

2015-09-01

Present study deals with the river Ganga water quality and its impact on metal speciation in its sediments. Concentration of physico-chemical parameters was highest in summer season followed by winter and lowest in rainy season. Metal speciation study in river sediments revealed that exchangeable, reducible and oxidizable fractions were dominant in all the studied metals (Cr, Ni, Cu, Zn, Cd, Pb) except Mn and Fe. High pollution load index (1.64-3.89) recommends urgent need of mitigation measures. Self-organizing Map-Artificial Neural Network (SOM-ANN) was applied to the data set for the prediction of major point sources of pollution in the river Ganga. Copyright © 2015 Elsevier Ltd. All rights reserved.

Speciation and bioavailability of some heavy metals in agricultural soils used for cultivating various vegetables in Bedugul, Bali

NASA Astrophysics Data System (ADS)

Siaka, I. Made; Utama, I. Made Supartha; Manuaba, I. B. Putra; Adnyana, I. Made; Sahara, Emmy

2016-03-01

This paper discusses the speciation and bioavailability of some heavy metals in agricultural soils used to cultivate various vegetables in Bedugul, Bali. Vegetables grown on contaminated soils where agrochemicals were applied uncontrolled could contain a number of heavy metals. This could occur in the vegetables produced from agricultural soils of Bedugul as the farmers applied agrochemicals excessively. In considering the metals transport to the vegetables, a speciation and bioavailability methods were necessary to be studied. Wet digestion and sequential extraction techniques were employed to the sample prior to the metals measurement by AAS. The results showed that the average concentrations of Pb, Cu, Cd, Cr, and Zn in the soils were 38.531, 132.126, 7.689, 15.952, and 147.275 mg/kg, respectively. The highest concentrations of Pb and Zn were found in the soil for cultivating lettuce, Cd and Cr in the soil for tomato, and Cu in the soil for potatoes. It was found that the speciation of Pb, Cu, Cd, and Cr were predominantly bound to Fe-Mn oxides fraction, while Zn was mostly associated with the EFLE (easily, freely, leachable, and exchangeable) fractions. The highest bioavailability among the metals in the studied soils was Cr, while the lowest was Cu.

Selective Separation and Determination of Heavy Metals (Cd, Pb, Cr) Speciation Forms from Hortic Antrosols

NASA Astrophysics Data System (ADS)

Bulgariu, D.; Bulgariu, L.

2009-04-01

The speciation, inter-phases distribution and biodisponibility of heavy metals in soils represent one of main problem of environmental geochemistry and agro-chemistry. This problem is very important in case of hortic antrosols (soils from glasshouses) for the elimination of agricultural products (fruits, vegetables) contamination with heavy metals. In soils from glass houses, the speciation and inter-phases distribution processes of heavy metals have a particular dynamic, different in comparison with those from non-protected soils. The predominant distribution forms of heavy metals in such soils types are: complexes with low mass organic molecules, organic-mineral complexes, complexes with inorganic ligands (hydroxide-complexes, carbonate-complexes, sulphate-complexes, etc.) and basic salts. All of these have high stabilities in conditions of soils from glass houses, and in consequence, the separation and determination of speciation forms (which is directly connected with biodisponibility of heavy metals) by usual methods id very difficult and has a high uncertain degree. In this study is presented an original method for the selective separation and differentiation of speciation forms of heavy metals from glass houses soils, which is based by the combination of solid-liquid sequential extraction (SPE) with the extraction in aqueous polymer-inorganic salt two-phase systems (ABS). The soil samples used for this study have been sampled from three different locations (glass houses from Iasi, Barlad and Bacau - Romania) where the vegetables cultivation have bee performed by three different technologies. In this way was estimated the applicability and the analytical limits of method proposed by as, in function of the chemical-mineralogical and physical-chemical characteristics of soils. As heavy metals have been studied cadmium, lead and chromium, all being known for their high toxicity. The procedure used for the selective separation and differentiation of speciation forms of heavy metals from glass houses soils has two main steps: (i) non-destructive separation of chemical-mineralogical associations and aggregates from soils samples - for this the separation method with heavy liquids (bromophorme) and isodynamic magnetic method have been used; (ii) sequential extraction of heavy metals from soil fractions separated in the first step, by using combined SPE-ABS procedure. For the preparation of combined extraction systems was used polyethylene glycol (with different molecular mass: 2000, 4000 and 8000). As phase-forming inorganic salts and as selective extracting agents we have used different usual inorganic reagents. The type and concentration of phase-forming salts have been selected in function of, both nature of extracted heavy metals and chemical-mineralogical characteristics of soil samples. The experimental parameters investigated in this study are: molecular mass of polyethylene glycol and the concentration of polymeric solutions, nature and concentration of phase-forming salts, nature and concentration of extracting agents, pH in extraction system phase, type of extracted heavy metals, type of speciation forms of heavy metals and their concentrations. All these factors can influence significantly the efficiency and the selectivity of separation process. The experimental results have indicate that the combined SPE-ABS extraction systems have better separation efficiency, in comparison with traditional SPE systems and ca realized a accurate discrimination between speciation forms of heavy metals from soils. Under these conditions, the estimation of inter-phases distribution and biodisponibility of heavy metals has a high precision. On the other hand, when the combined SPE-ABS systems are used, the concomitant extraction of the elements from the same geochemical association with studied heavy metals (inevitable phenomena in case of separation by SPE procedures) is significant diminished. This increases the separation selectivity and facilitated the more accurate determination of speciation forms concentration. By adequate selection of extraction conditions can be realized the selective separation of organic-mineral complexes, which will permit to perform detailed studies about the structure and chemical composition of these. Acknowledgments The authors would like to acknowledge the financial support from Romanian Ministry of Education and Research (Project PNCDI 2-D5 no. 51045/07).

Speciation analysis of mercury by solid-phase microextraction and multicapillary gas chromatography hyphenated to inductively coupled plasma-time-of-flight-mass spectrometry.

PubMed

Jitaru, Petru; Adams, Freddy C

2004-11-05

This paper reports the development of an analytical approach for speciation analysis of mercury at ultra-trace levels on the basis of solid-phase microextraction and multicapillary gas chromatography hyphenated to inductively coupled plasma-time-of-flight mass spectrometry. Headspace solid-phase microextraction with a carboxen/polydimethylsyloxane fiber is used for extraction/preconcentration of mercury species after derivatization with sodium tetraethylborate and subsequent volatilization. Isothermal separation of methylmercury (MeHg), inorganic mercury (Hg2+) and propylmercury (PrHg) used as internal standard is achieved within a chromatographic run below 45 s without the introduction of spectral skew. Method detection limits (3 x standard deviation criteria) calculated for 10 successive injections of the analytical reagent blank are 0.027 pg g(-1) (as metal) for MeHg and 0.27 pg g(-1) for Hg2+. The repeatability (R.S.D., %) is 3.3% for MeHg and 3.8% for Hg2+ for 10 successive injections of a standard mixture of 10pg. The method accuracy for MeHg and total mercury is validated through the analysis of marine and estuarine sediment reference materials. A comparison of the sediment data with those obtained by a purge-and-trap injection (PTI) method is also addressed. The analytical procedure is illustrated with some results for the ultra-trace level analysis of ice from Antarctica for which the accuracy is assessed by spike recovery experiments.

Influence of population density on the concentration and speciation of metals in the soil and street dust from urban areas.

PubMed

Acosta, J A; Gabarrón, M; Faz, A; Martínez-Martínez, S; Zornoza, R; Arocena, J M

2015-09-01

Street dust and soil from high, medium and low populated cities and natural area were analysed for selected physical-chemical properties, total and chemical speciation of Zn, Pb, Cu, Cr, Cd, Co, Ni to understand the influence of human activities on metal accumulation and mobility in the environment. The pH, salinity, carbonates and organic carbon contents were similar between soil and dust from the same city. Population density increases dust/soil salinity but has no influence on metals concentrations in soils. Increases in metal concentrations with population density were observed in dusts. Cu, Zn, Pb, Cr can be mobilized more easily from dust compared to the soil. In addition, population density increase the percentage of Pb and Zn associated to reducible and carbonate phase in the dust. The behaviour of metals except Cd in soil is mainly affected by physico-chemical properties, while total metal influenced the speciation except Cr and Ni in dusts. Copyright © 2015 Elsevier Ltd. All rights reserved.

Trace Metal Distribution and Speciation in Pore Water of Hydrothermal Sediments From the Guaymas Basin, Gulf of California

NASA Astrophysics Data System (ADS)

Morales-Villafuerte, M.; Ortega-Osorio, A.; Wheat, G.; Seewald, J.

2004-12-01

Thirteen sediment cores were collected through out direct sampling with the MBARI/ ROV "Tiburon" in the southern trough of the Guaymas Basin in March 2003. Pore water samples from regular 2.5 cm intervals of sediment cores were extracted onboard by centrifugation. The supernatants were collected in clean polystyrene vials and stored at 4° C until analytical work on shore. Dissolved Fe, Mn, Cu, Pb, Zn and Ni concentrations in extracted fluid samples were analyzed by direct injection of atomic absorption spectrometry. Four zones in the hydrothermal field were classified according to their physical characteristics. A core located away from the influence of active vents was recovered as a background site. The second zone is characterized by low temperatures (4.2-80° C) and sediments saturated in hydrocarbons. Sulfides formation and higher temperatures (4-166° C) were observed in the third zone. Precipitation of carbonates on top of the sediment characterizes the fourth zone. Concentration of trace metals at the water-sediment interface appears to be the highest, probably due to metal precipitation from the hydrothermal plume, followed by diffusion into the pore water. A decrease in concentration is observed between 5-12 cm depth, suggesting that biological activity is consuming essential metals (zone of bioturbation). Metal concentrations in zones where sulfide phases are rich, exhibit smaller values in pore water (Fe=2.4-3.8 μ mol/kg, Cu=0.6-0.8 μ mol/kg, Pb=1.2-1.5 μ mol/kg, Zn=0.4-0.5 μ mol/kg and Ni= 3.4-4.4 μ mol/kg) relative to samples located at hydrocarbon sites (Fe= 2.7-11.4, Cu= 0.7-1.0 μ mol/kg, Pb= 1.2-2.2 μ mol/kg, Zn= 0.4-0.7 μ mol/kg and Ni= 3.4-5.2 μ mol/kg). At sulfide zones, pH and Eh conditions help to precipitate their stable sulfides as opposed to the hydrocarbon areas, where conditions are not favorable for sulfide formation due to the absence of H2S. In general, Fe concentrations in pore water are lower than that of Mn, very likely due to the easier precipitation and greater stability of FeS relative to MnS. As an attempt to reconstruct predominant species and their abundance in the system, aqueous chemical models were applied. The codes EQBRM and SUPCRT92 were run with total concentrations to calculate, concentrations, activity coefficients and thermodynamic properties of aqueous species. Experimental data such as total chloride, total sulfur and measured pH were used in the model. According to the prevailing conditions in the Guaymas Basin, all metals studied form chloride complexes. Iron, lead, and zinc exist mainly as hydroxy complexes, manganese as free ion and copper as CuHS. Speciation results are well supported by the Pearson's hard-soft rule which states that soft metal ion Cu++ bonds with soft bisulfide ligand, likewise, borderline metal ions as Fe2+, Mn2+, Pb2+ and Zn2+ bond with chloride, hydroxyl or water ligands. The results reported here provide a greater insight into the behavior of trace metals in pore waters of hydrothermal sediments.

EPA’s SPECIATE 4.4 Database - Development and Uses

EPA Science Inventory

SPECIATE is the EPA's repository of TOG, PM, and Other Gases speciation profiles of air pollution sources. It includes weight fractions of both organic species and PM and provides data in consistent units. Species include metals, ions, elements, and organic and inorganic compound...

Metal speciation in landfill leachates with a focus on the influence of organic matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Claret, Francis, E-mail: f.claret@brgm.fr; Tournassat, Christophe; Crouzet, Catherine

Highlights: > This study characterises the heavy-metal content in leachates collected from eight landfills in France. > Most of the metals are concentrated in the <30 kDa fraction, while Pb, Cu and Cd are associated with larger particles. > Metal complexation with OM is not sufficient to explain apparent supersaturation of metals with sulphide minerals. - Abstract: This study characterises the heavy-metal content in leachates collected from eight landfills in France. In order to identify heavy metal occurrence in the different size fractions of leachates, a cascade filtration protocol was applied directly in the field, under a nitrogen gas atmospheremore » to avoid metal oxidation. The results of analyses performed on the leachates suggest that most of the metals are concentrated in the <30 kDa fraction, while lead, copper and cadmium show an association with larger particles. Initial speciation calculations, without considering metal association with organic matter, suggest that leachate concentrations in lead, copper, nickel and zinc are super-saturated with respect to sulphur phases. Speciation calculations that account for metal complexation with organic matter, considered as fulvic acids based on C1(s) NEXAFS spectroscopy, show that this mechanism is not sufficient to explain such deviation from equilibrium conditions. It is therefore hypothesized that the deviation results also from the influence of biological activity on the kinetics of mineral phase precipitation and dissolution, thus providing a dynamic system. The results of chemical analyses of sampled fluids are compared with speciation calculations and some implications for the assessment of metal mobility and natural attenuation in a context of landfill risk assessment are discussed.« less

Strategies to predict metal mobility in surficial mining environments

USGS Publications Warehouse

Smith, Kathleen S.

2007-01-01

This report presents some strategies to predict metal mobility at mining sites. These strategies are based on chemical, physical, and geochemical information about metals and their interactions with the environment. An overview of conceptual models, metal sources, and relative mobility of metals under different geochemical conditions is presented, followed by a discussion of some important physical and chemical properties of metals that affect their mobility, bioavailability, and toxicity. The physical and chemical properties lead into a discussion of the importance of the chemical speciation of metals. Finally, environmental and geochemical processes and geochemical barriers that affect metal speciation are discussed. Some additional concepts and applications are briefly presented at the end of this report.

Urban gardens: Lead exposure, recontamination mechanisms, and implications for remediation design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, Heather F.; Hausladen, Debra M.; Brabander, Daniel J.

2008-07-15

Environmental lead contamination is prevalent in urban areas where soil represents a significant sink and pathway of exposure. This study characterizes the speciation of lead that is relevant to local recontamination and to human exposure in the backyard gardens of Roxbury and Dorchester, MA, USA. One hundred forty-one backyard gardens were tested by X-ray fluorescence, and 81% of gardens have lead levels above the US EPA action limit of 400 {mu}g/g. Raised gardening beds are the in situ exposure reduction method used in the communities to promote urban gardening. Raised beds were tested for lead and the results showed thatmore » the lead concentration increased from an initial range of 150{+-}40 {mu}g/g to an average of 336 {mu}g/g over 4 years. The percent distribution of lead in the fine grain soil (<100 {mu}m) and the trace metal signature of the raised beds support the conclusion that the mechanism of recontamination is wind-transported particles. Scanning electron microscopy and sequential extraction were used to characterize the speciation of lead, and the trace metal signature of the fine grain soil in both gardens and raised gardening beds is characteristic of lead-based paint. This study demonstrates that raised beds are a limited exposure reduction method and require maintenance to achieve exposure reduction goals. An exposure model was developed based on a suite of parameters that combine relevant values from the literature with site-specific quantification of exposure pathways. This model suggests that consumption of homegrown produce accounts for only 3% of children's daily exposure of lead while ingestion of fine grained soil (<100 {mu}m) accounts for 82% of the daily exposure. This study indicates that urban lead remediation on a yard-by-yard scale requires constant maintenance and that remediation may need to occur on a neighborhood-wide scale.« less

Urban gardens: lead exposure, recontamination mechanisms, and implications for remediation design.

PubMed

Clark, Heather F; Hausladen, Debra M; Brabander, Daniel J

2008-07-01

Environmental lead contamination is prevalent in urban areas where soil represents a significant sink and pathway of exposure. This study characterizes the speciation of lead that is relevant to local recontamination and to human exposure in the backyard gardens of Roxbury and Dorchester, MA, USA. One hundred forty-one backyard gardens were tested by X-ray fluorescence, and 81% of gardens have lead levels above the US EPA action limit of 400 microg/g. Raised gardening beds are the in situ exposure reduction method used in the communities to promote urban gardening. Raised beds were tested for lead and the results showed that the lead concentration increased from an initial range of 150+/-40 microg/g to an average of 336 microg/g over 4 years. The percent distribution of lead in the fine grain soil (<100 microm) and the trace metal signature of the raised beds support the conclusion that the mechanism of recontamination is wind-transported particles. Scanning electron microscopy and sequential extraction were used to characterize the speciation of lead, and the trace metal signature of the fine grain soil in both gardens and raised gardening beds is characteristic of lead-based paint. This study demonstrates that raised beds are a limited exposure reduction method and require maintenance to achieve exposure reduction goals. An exposure model was developed based on a suite of parameters that combine relevant values from the literature with site-specific quantification of exposure pathways. This model suggests that consumption of homegrown produce accounts for only 3% of children's daily exposure of lead while ingestion of fine grained soil (<100 microm) accounts for 82% of the daily exposure. This study indicates that urban lead remediation on a yard-by-yard scale requires constant maintenance and that remediation may need to occur on a neighborhood-wide scale.

Algae metabolism and organic carbon in sediments determining arsenic mobilisation in ground- and surface water. A field study in Doñana National Park, Spain.

PubMed

Kohfahl, Claus; Navarro, Daniel Sánchez-Rodas; Mendoza, Jorge Armando; Vadillo, Iñaki; Giménez-Forcada, Elena

2016-02-15

A study has been performed to explore the origin, spatiotemporal behaviour and mobilisation mechanism of the elevated arsenic (As) concentrations found in ground water and drinking ponds of the Doñana National Park, Southern Spain. At a larger scale, 13 piezometers and surface water samples of about 50 artificial drinking ponds and freshwater lagoons throughout the National Park were collected and analysed for major ions, metals and trace elements. At a smaller scale, 5 locations were equipped with piezometers and groundwater was sampled up to 4 times for ambient parameters, major ions, metals, trace elements and iron (Fe) speciation. As was analysed for inorganic and organic speciation. Undisturbed sediment samples were analysed for physical parameters, mineralogy, geochemistry as well as As species. Sediment analyses yielded total As between 0.1 and 18 mg/kg and are not correlated with As concentration in water. Results of the surface- and groundwater sampling revealed elevated concentration of As up to 302 μg/L within a restricted area of the National Park. Results of groundwater sampling reveals strong correlation of As with Fe(2+) pointing to As mobilisation due to reductive dissolution of hydroferric oxides (HFO) in areas of locally elevated amounts of organic matter within the sediments. High As concentrations in surface water ponds are correlated with elevated alkalinity and pH attributed to algae metabolism, leading to As desorption from HFO. The algae metabolism is responsible for the presence of methylated arsenic species in surface water, in contrast to ground water in which only inorganic As species was found. Temporal variations in surface water and groundwater are also related to changes in pH and alkalinity as a result of enhanced algae metabolism in surface water or related to changes in the redox level in the case of groundwater. Copyright © 2015 Elsevier B.V. All rights reserved.

Ni cycling in mangrove sediments from New Caledonia

NASA Astrophysics Data System (ADS)

Noël, Vincent; Morin, Guillaume; Juillot, Farid; Marchand, Cyril; Brest, Jessica; Bargar, John R.; Muñoz, Manuel; Marakovic, Grégory; Ardo, Sandy; Brown, Gordon E.

2015-11-01

Covering more than 70% of tropical and subtropical coastlines, mangrove intertidal forests are well known to accumulate potentially toxic trace metals in their sediments, and thus are generally considered to play a protective role in marine and lagoon ecosystems. However, the chemical forms of these trace metals in mangrove sediments are still not well known, even though their molecular-level speciation controls their long-term behavior. Here we report the vertical and lateral changes in the chemical forms of nickel, which accumulates massively in mangrove sediments downstream from lateritized ultramafic deposits from New Caledonia, where one of nature's largest accumulations of nickel occurs. To accomplish this we used Ni K-edge Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy data in combination with microscale chemical analyses using Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy (SEM-EDXS). After Principal Component and Target Transform analyses (PCA-TT), the EXAFS data of the mangrove sediments were reliably least-squares fitted by linear combination of 3-components chosen from a large model compound spectral database including synthetic and natural Ni-bearing sulfides, clay minerals, oxyhydroxides, and organic complexes. Our results show that in the inland salt flat Ni is hosted in minerals inherited from the eroded lateritic materials, i.e. Ni-poor serpentine (44-58%), Ni-rich talc (20-31%), and Ni-goethite (18-24%). In contrast, in the hydromorphic sediments beneath the vegetated Avicennia and Rhizophora stands, a large fraction of Ni is partly redistributed into a neoformed smectite pool (20-69% of Ni-montmorillonite), and Ni speciation significantly changes with depth in the sediment. Indeed, Ni-rich talc (25-56%) and Ni-goethite (15-23%) disappear below ∼15 cm depth in the sediment and are replaced by Ni-sorbed pyrite (23-52%) in redox-active intermediate depth layers and by pyrite (34-55%) in the deepest sediment layers. Ni-incorporation in pyrite is especially observed beneath an inland Avicennia stand where anoxic conditions are dominant. In contrast, beneath a Rhizophora stand closer to the ocean, where the redox cycle is intensified due to the tide cycle, partial re-oxidation of Ni-bearing pyrites favors nickel mobility, as confirmed by Ni-mass balance estimates and by higher Ni concentration in the pore waters. These findings have important environmental implications for better evaluating the protective role of mangroves against trace metal dispersion into marine ecosystems. They may also help in predicting the response of mangrove ecosystems to increasing anthropogenic pressure on coastal areas.

Speciated Elemental and Isotopic Characterization of Atmospheric Aerosols - Recent Advances

NASA Astrophysics Data System (ADS)

Shafer, M.; Majestic, B.; Schauer, J.

2007-12-01

Detailed elemental, isotopic, and chemical speciation analysis of aerosol particulate matter (PM) can provide valuable information on PM sources, atmospheric processing, and climate forcing. Certain PM sources may best be resolved using trace metal signatures, and elemental and isotopic fingerprints can supplement and enhance molecular maker analysis of PM for source apportionment modeling. In the search for toxicologically relevant components of PM, health studies are increasingly demanding more comprehensive characterization schemes. It is also clear that total metal analysis is at best a poor surrogate for the bioavailable component, and analytical techniques that address the labile component or specific chemical species are needed. Recent sampling and analytical developments advanced by the project team have facilitated comprehensive characterization of even very small masses of atmospheric PM. Historically; this level of detail was rarely achieved due to limitations in analytical sensitivity and a lack of awareness concerning the potential for contamination. These advances have enabled the coupling of advanced chemical characterization to vital field sampling approaches that typically supply only very limited PM mass; e.g. (1) particle size-resolved sampling; (2) personal sampler collections; and (3) fine temporal scale sampling. The analytical tools that our research group is applying include: (1) sector field (high-resolution-HR) ICP-MS, (2) liquid waveguide long-path spectrophotometry (LWG-LPS), and (3) synchrotron x-ray absorption spectroscopy (sXAS). When coupled with an efficient and validated solubilization method, the HR-ICP-MS can provide quantitative elemental information on over 50 elements in microgram quantities of PM. The high mass resolution and enhanced signal-to-noise of HR-ICP-MS significantly advance data quality and quantity over that possible with traditional quadrupole ICP-MS. The LWG-LPS system enables an assessment of the soluble/labile components of PM, while simultaneously providing critical oxidation state speciation data. Importantly, the LWG- LPS can be deployed in a semi-real-time configuration to probe fine temporal scale variations in atmospheric processing or sources of PM. The sXAS is providing complementary oxidation state speciation of bulk PM. Using examples from our research; we will illustrate the capabilities and applications of these new methods.

[Analysis of primary elemental speciation distribution in mungbean during enzymatic hydrolization].

PubMed

Li, Ji-Hua; Huang, Mao-Fang; Zhu, De-Ming; Zheng, Wei-Wan; Zhong, Ye-Jun

2009-03-01

In the present paper, trace elements contents of cuprum, zincum, manganese and ferrum in mungbean and their primary speciation distribution during enzymatic hydrolization were investigated with ICP-AES OPTIMA 5300DV plasma emission spectroscopy. The trace elements were separated into two forms, i.e. dissolvable form and particulate form, by cellulose membrane with 0.45 microm of pore diameter. All the samples were digested by strong acid (perchloric acid and nitric acid with 1 : 4 ratio ). The parameters of primary speciations of the four elements were calculated and discussed. The results showed: (1) Contents of cuprum, zincum, manganese and ferrum in mungbean were 12.77, 31.26, 18.14 and 69.38 microg x g(-1) (of dry matter), respectively. Different treatment resulted in different elemental formulation in product, indicating that more attention should be paid to the trace elements pattern when producing mungbean beverage with different processes. (2) Extraction rates of cuprum, zincum, manganese and ferrum in extract were 68.84%, 51.84%, 63.97% and 30.40% with enzymatic treatments and 36.22%, 17.58%, 7.85% and 22.99% with boil treatment, respectively. Both boil and enzymatic treatments led to poor elemental extraction rates, which proved that it was necessary to take deep enzymatic hydrolysis treatment in mungbean beverage process as the trace element utilization rate was concerned. (3) Amylase, protease and cellulose showed different extraction effectiveness of the four trace elements. Generally, protease exhibited highest efficiency for the four elements extraction. All of the four trace elements were mostly in dissolvable form in all hydrolysates and soup. (4) Relative standard deviations and recovery yields are within 0.12%-0.90% (n = 11) and 98.6%-101.4%, respectively. The analysis method in this paper proved to be accurate.

Metal complexation properties of freshwater dissolved organic matter are explained by its aromaticity and by anthropogenic ligands.

PubMed

Baken, Stijn; Degryse, Fien; Verheyen, Liesbeth; Merckx, Roel; Smolders, Erik

2011-04-01

Dissolved organic matter (DOM) in surface waters affects the fate and environmental effects of trace metals. We measured variability in the Cd, Cu, Ni, and Zn affinity of 23 DOM samples isolated by reverse osmosis from freshwaters in natural, agricultural, and urban areas. Affinities at uniform pH and ionic composition were assayed at low, environmentally relevant free Cd, Cu, Ni, and Zn activities. The C-normalized metal binding of DOM varied 4-fold (Cu) or about 10-fold (Cd, Ni, Zn) among samples. The dissolved organic carbon concentration ranged only 9-fold in the waters, illustrating that DOM quality is an equally important parameter for metal complexation as DOM quantity. The UV-absorbance of DOM explained metal affinity only for waters receiving few urban inputs, indicating that in those waters, aromatic humic substances are the dominant metal chelators. Larger metal affinities were found for DOM from waters with urban inputs. Aminopolycarboxylate ligands (mainly EDTA) were detected at concentrations up to 0.14 μM and partly explained the larger metal affinity. Nickel concentrations in these surface waters are strongly related to EDTA concentrations (R2=0.96) and this is underpinned by speciation calculations. It is concluded that metal complexation in waters with anthropogenic discharges is larger than that estimated with models that only take into account binding on humic substances.

The influence of metal speciation in combustion waste on the efficiency of Cu, Pb, Zn, Cd, Ni and Cr bioleaching in a mixed culture of sulfur-oxidizing and biosurfactant-producing bacteria.

PubMed

Karwowska, Ewa; Wojtkowska, Małgorzata; Andrzejewska, Dorota

2015-12-15

Metal leachability from ash and combustion slag is related to the physico-chemical properties, including their speciation in the waste. Metals speciation is an important factor that influences the efficiency of metal bioleaching from combustion wastes in a mixed culture of acidophilic and biosurfactant-producing bacteria. It was observed that individual metals tended to occur in different fractions, which reflects their susceptibility to bioleaching. Cr and Ni were readily removed from wastes when present with a high fraction bound to carbonates. Cd and Pb where not effectively bioleached when present in high amounts in a fraction bound to organic matter. The best bioleaching results were obtained for power plant slag, which had a high metal content in the exchangeable, bound to carbonates and bound to Fe and Mg oxides fractions- the metal recovery percentage for Zn, Cu and Ni from this waste exceeded 90%. Copyright © 2015 Elsevier B.V. All rights reserved.

Gas and liquid chromatography with inductively coupled plasma mass spectrometry detection for environmental speciation analysis — advances and limitations

NASA Astrophysics Data System (ADS)

Szpunar, Joanna; McSheehy, Shona; Połeć, Kasia; Vacchina, Véronique; Mounicou, Sandra; Rodriguez, Isaac; Łobiński, Ryszard

2000-07-01

Recent advances in the coupling of gas chromatography (GC) and high performance liquid chromatography (HPLC) with inductively coupled plasma mass spectrometry (ICP MS) and their role in trace element speciation analysis of environmental materials are presented. The discussion is illustrated with three research examples concerning the following topics: (i) development and coupling of multicapillary microcolumn GC with ICP MS for speciation of organotin in sediment and biological tissue samples; (ii) speciation of arsenic in marine algae by size-exclusion-anion-exchange HPLC-ICP MS; and (iii) speciation of cadmium in plant cell cultures by size-exclusion HPLC-ICP MS. Particular attention is paid to the problem of signal identification in ICP MS chromatograms; the potential of electrospray MS/MS for this purpose is highlighted.

Metal-organic complexes in geochemical processes: temperature dependence of the standard thermodynamic properties of aqueous complexes between metal cations and dicarboxylate ligands

NASA Astrophysics Data System (ADS)

Prapaipong, Panjai; Shock, Everett L.; Koretsky, Carla M.

1999-10-01

By combining results from regression and correlation methods, standard state thermodynamic properties for aqueous complexes between metal cations and divalent organic acid ligands (oxalate, malonate, succinate, glutarate, and adipate) are evaluated and applied to geochemical processes. Regression of experimental standard-state equilibrium constants with the revised Helgeson-Kirkham-Flowers (HKF) equation of state yields standard partial molal entropies (S¯°) of aqueous metal-organic complexes, which allow determination of thermodynamic properties of the complexes at elevated temperatures. In cases where S¯° is not available from either regression or calorimetric measurement, the values of S¯° can be estimated from a linear correlation between standard partial molal entropies of association (ΔS¯°r) and standard partial molal entropies of aqueous cations (S¯°M). The correlation is independent of cation charge, which makes it possible to predict S¯° for complexes between divalent organic acids and numerous metal cations. Similarly, correlations between standard Gibbs free energies of association of metal-organic complexes (ΔḠ°r) and Gibbs free energies of formation (ΔḠ°f) for divalent metal cations allow estimates of standard-state equilibrium constants where experimental data are not available. These correlations are found to be a function of ligand structure and cation charge. Predicted equilibrium constants for dicarboxylate complexes of numerous cations were included with those for inorganic and other organic complexes to study the effects of dicarboxylate complexes on the speciation of metals and organic acids in oil-field brines. Relatively low concentrations of oxalic and malonic acids affect the speciation of cations more than similar concentrations of succinic, glutaric, and adipic acids. However, the extent to which metal-dicarboxylate complexes contribute to the speciation of dissolved metals depends on the type of dicarboxylic acid ligand; relative concentration of inorganic, mono-, and dicarboxylate ligands; and the type of metal cation. As an example, in the same solution, dicarboxylic acids have a greater influence on the speciation of Fe+2 and Mg+2 than on the speciation of Zn+2 and Mn+2.

Incorporation of Metals into Calcite in a Deep Anoxic Granite Aquifer.

PubMed

Drake, Henrik; Mathurin, Frédéric A; Zack, Thomas; Schäfer, Thorsten; Roberts, Nick Mw; Whitehouse, Martin; Karlsson, Andreas; Broman, Curt; Åström, Mats E

2018-01-16

Understanding metal scavenging by calcite in deep aquifers in granite is of importance for deciphering and modeling hydrochemical fluctuations and water-rock interaction in the upper crust and for retention mechanisms associated with underground repositories for toxic wastes. Metal scavenging into calcite has generally been established in the laboratory or in natural environments that cannot be unreservedly applied to conditions in deep crystalline rocks, an environment of broad interest for nuclear waste repositories. Here, we report a microanalytical study of calcite precipitated over a period of 17 years from anoxic, low-temperature (14 °C), neutral (pH: 7.4-7.7), and brackish (Cl: 1700-7100 mg/L) groundwater flowing in fractures at >400 m depth in granite rock. This enabled assessment of the trace metal uptake by calcite under these deep-seated conditions. Aquatic speciation modeling was carried out to assess influence of metal complexation on the partitioning into calcite. The resulting environment-specific partition coefficients were for several divalent ions in line with values obtained in controlled laboratory experiments, whereas for several other ions they differed substantially. High absolute uptake of rare earth elements and U(IV) suggests that coprecipitation into calcite can be an important sink for these metals and analogousactinides in the vicinity of geological repositories.

Speciation evolution of zinc and copper during pyrolysis and hydrothermal carbonization treatments of sewage sludges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Rixiang; Zhang, Bei; Saad, Emily M.

Thermal and hydrothermal treatments are promising techniques for sewage sludge management that can potentially facilitate safe waste disposal, energy recovery, and nutrient recovery/recycling. Content and speciation of heavy metals in the treatment products affect the potential environmental risks upon sludge disposal and/or application of the treatment products. Therefore, it is important to study the speciation transformation of heavy metals and the effects of treatment conditions. By combining synchrotron X-ray spectroscopy/microscopy analysis and sequential chemical extraction, this study systematically characterized the speciation of Zn and Cu in municipal sewage sludges and their chars derived from pyrolysis (a representative thermal treatment technique)more » and hydrothermal carbonization (HTC; a representative hydrothermal treatment technique). Spectroscopy analysis revealed enhanced sulfidation of Zn and Cu by anaerobic digestion and HTC treatments, as compared to desulfidation by pyrolysis. Overall, changes in the chemical speciation and matrix properties led to reduced mobility of Zn and Cu in the treatment products. These results provide insights into the reaction mechanisms during pyrolysis and HTC treatments of sludges and can help evaluate the environmental/health risks associated with the metals in the treatment products.« less

pH : a key control of the nature and distribution of dissolved organic matter and associated trace metals in soil

NASA Astrophysics Data System (ADS)

Pédrot, M.; Dia, A.; Davranche, M.

2009-04-01

Dissolved organic matter is ubiquitous at the Earth's surface and plays a prominent role in controlling metal speciation and mobility from soils to hydrosystems. Humic substances (HS) are usually considered to be the most reactive fraction of organic matter. Humic substances are relatively small and formed by chemically diverse organic molecules, bearing different functional groups that act as binding sites for cations and mineral surfaces. Among the different environmental physicochemical parameters controlling the metal speciation, pH is likely to be the most important one. Indeed, pH affect the dissociation of functional groups, and thus can influence the HS structure, their ability to complex metals, their solubility degree allowing the formation of aggregates at the mineral surface. In this context, soil/water interactions conducted through batch system experiments, were carried out with a wetland organic-rich soil to investigate the effect of pH on the release of dissolved organic carbon (DOC) and associated trace elements. The pH was regulated between 4 and 7.5 using an automatic pH stat titrator. Ultrafiltration experiments were performed to separate the dissolved organic pool following decreasing pore sizes (30 kDa, 5 kDa and 2 kDa with 1 Da = 1 g.mol-1). The pH increase induced a significant DOC release, especially in heavy organic molecules (size >5 kDa) with a high aromaticity (>30 %). These were probably humic acids (HA). This HA release influenced (i) directly the trace element concentrations in soil solution since HA were enriched in several trace elements such as Th, REE, Y, U, Cr and Cu; and (ii) indirectly by the breaking of clay-humic complexes releasing Fe- and Al-rich nanoparticles associated with V, Pb and Ti. By contrast, at acid pH, most HS were complexed onto mineral surfaces. They also sequestered iron nanoparticles. Therefore, at low pH, most part of DOC molecules had a size < 5 kDa and lower aromaticity. Thus, the DOC was mostly composed of simple organic compounds little complexing. Consequently, the soil solution was depleted in trace elements such as Th, REE, Y, U, Cr, Cu, Al, Fe, V, Pb and Ti, but also enriched in Ca, Sr, Ba, Mn, Mg, Co, Zn and in a lesser proportion in Rb, Li and Ni. The aromaticity in the fractions <5 kDa was higher than in the fractions <30 kDa or <0.2 µm. Complementary experiments were performed to understand the HS size distribution and aromaticity according to pH and ionic strength .The molecular size and shape of HS is usually explained by two concepts: (i) the macropolymeric structure with heavy organic molecules considered to be flexible linear polyelectrolytes and (ii) the supramolecular structure with an association of a complex mixture of different molecules held together by dispersive weak forces. Ours results supported the HA supramolecular structure at neutral or basic pH conditions. But, at acid pH, a disruption of the humic supramolecular associations involved the release of small organic molecules with a high aromaticity. Moreover, this aromaticity variation can be due also to the presence of fulvic acids in the fractions <5 kDa and a mixture of heavy organic molecules little complexing in the fractions >5 kDa. These latter molecules displayed a low aromaticity decreasing the global aromaticity of the fractions <30 kDa and <0.2 µm. To summarize, these new data demonstrated that the DOC and trace element concentrations of the soil solutions were strongly controlled by pH. This parameter influenced the nature and the size of the DOC as well as, the trace element concentrations in the soil solutions, with a decreasing contribution of HA when pH decreased. This pH dependence is a key issue of concern since local (human pressure) and/or global (climatic) warning result in pH water changes.

Chemical Speciation and Quantitative Evaluation of Heavy Metal Pollution Hazards in Two Army Shooting Range Backstop Soils.

PubMed

Islam, Mohammad Nazrul; Nguyen, Xuan Phuc; Jung, Ho-Young; Park, Jeong-Hun

2016-02-01

The chemical speciation and ecological risk assessment of heavy metals in two shooting range backstop soils in Korea were studied. Both soils were highly contaminated with Cd, Cu, Pb, and Sb. The chemical speciation of heavy metals reflected the present status of contamination, which could help in promoting management practices. We-rye soil had a higher proportion of exchangeable and carbonate bound metals and water-extractable Cd and Sb than the Cho-do soil. Bioavailable Pb represented 42 % of the total Pb content in both soils. A significant amount of Sb was found in the two most bioavailable fractions, amounting to ~32 % in the soil samples, in good agreement with the batch leaching test using water. Based on the values of ecological risk indices, both soils showed extremely high potential risk and may represent serious environmental problems.

[Speciation Characteristics and Bioavailability of Heavy Metals in Oasis Soil Under Pb, Zn Combined Stress].

PubMed

Jin, Cheng; Zhao, Zhuan-jun; Nan, Zhong-ren; Wang, Sheng-li; Wu, Wen-fei; Wang, Hou-cheng

2015-05-01

Pot experiments were conducted on cole (Brassica) grown in oasis soil under combined stress of lead and zinc, to study the effect of heavy metal combined pollution on cole growth as well as the speciation conversion rules and bioavailability. The result showed that the promoting effect on cole growth was shown in the low concentration treatments, especially on stem leaves. With addition of exotic heavy metals, the main speciations of Pb and Zn in the soil transformed from tight-bound to loose-bound forms as compared to the control, and the bioavailability of heavy metals was increased. And, the exchangeable Pb and the carbonate bound form of Zn were the major contributing speciations which were absorbed in different parts of cole. What's more, the capabilities of uptake and translocation of Pb and Zn by cole were stronger at lower stress levels, and the enrichment and migration coefficients decreased with the increasing content of bioavailable fraction of the corresponding element or the coexisting element. In all treatments, the Pb concentration in the stem leaves of cole exceeded the food safety threshold, therefore it is recommended to conduct detection of relevant indicators before planting foliage vegetables in this kind of soil.

Metals, Health and the Environment – Emergence of Correlations Between Speciation and Effects

PubMed Central

Williams, David R.

2004-01-01

Over the last half-century both the identification of the causes of diseases and the use of inorganic compounds to treat such conditions have been considerably enlightened through our emerging capabilities to identify the pivotal chemical species involved. The ‘duty of care’ placed upon scientists to protect the environment from manufactured chemicals and to limit their effects upon humans therefrom is best realised from a speciation knowledge database. This paper discusses categorising chemicals in terms of their persistence, bioaccumulation, and toxicities and uses speciation information to optimise desirable effects of chemicals in several applications such as the manufacture of pulp for paper and in the foliar nutrition of crops. Simultaneously, the chemical wasting side effects of industrial overdosing is easily avoided if speciation approaches are used. The move towards new environmentally friendly ligand agents is described and methods of finding substitute agents (often combinations of two or more chemicals) to replace nonbiodegradable EDTA. The geosphere migration of metals through the environment is discussed in terms of speciation. Future objectives discussed include improved means of communicating speciation-based recommendations to decision makers. PMID:18365083

Mercury (II) reduction and co-precipitation of metallic mercury on hydrous ferric oxide in contaminated groundwater.

PubMed

Richard, Jan-Helge; Bischoff, Cornelia; Ahrens, Christian G M; Biester, Harald

2016-01-01

Mercury (Hg) speciation and sorption analyses in contaminated aquifers are useful for understanding transformation, retention, and mobility of Hg in groundwater. In most aquifers hydrous ferric oxides (HFOs) are among the most important sorbents for trace metals; however, their role in sorption or mobilization of Hg in aquifers has been rarely analyzed. In this study, we investigated Hg chemistry and Hg sorption to HFO under changing redox conditions in a highly HgCl2-contaminated aquifer (up to 870μgL(-1) Hg). Results from aqueous and solid phase Hg measurements were compared to modeled (PHREEQC) data. Speciation analyses of dissolved mercury indicated that Hg(II) forms were reduced to Hg(0) under anoxic conditions, and adsorbed to or co-precipitated with HFO. Solid phase Hg thermo-desorption measurements revealed that between 55 and 93% of Hg bound to HFO was elemental Hg (Hg(0)). Hg concentrations in precipitates reached more than 4 weight %, up to 7000 times higher than predicted by geochemical models that do not consider unspecific sorption to and co-precipitation of elemental Hg with HFO. The observed process of Hg(II) reduction and Hg(0) formation, and its retention and co-precipitation by HFO is thought to be crucial in HgCl2-contaminated aquifers with variable redox-conditions regarding the related decrease in Hg solubility (factor of ~10(6)), and retention of Hg in the aquifer. Copyright © 2015 Elsevier B.V. All rights reserved.

Recrystallization of Manganite (γ-MnOOH) and Implications for Trace Element Cycling.

PubMed

Hens, Tobias; Brugger, Joël; Cumberland, Susan A; Etschmann, Barbara; Frierdich, Andrew J

2018-02-06

The recrystallization of Mn(III,IV) oxides is catalyzed by aqueous Mn(II) (Mn(II) aq ) during (bio)geochemical Mn redox cycling. It is poorly understood how trace metals associated with Mn oxides (e.g., Ni) are cycled during such recrystallization. Here, we use X-ray absorption spectroscopy (XAS) to examine the speciation of Ni associated with Manganite (γ-Mn(III)OOH) suspensions in the presence or absence of Mn(II) aq under variable pH conditions (pH 5.5 and 7.5). In a second set of experiments, we used a 62 Ni isotope tracer to quantify the amount of dissolved Ni that exchanges with Ni incorporated in the Manganite crystal structure during reactions in 1 mM Mn(II) aq and in Mn(II)-free solutions. XAS spectra show that Ni is initially sorbed on the Manganite mineral surface and is progressively incorporated into the mineral structure over time (13% after 51 days) even in the absence of dissolved Mn(II). The amount of Ni incorporation significantly increases to about 40% over a period of 51 days when Mn(II) aq is present in solution. Similarly, Mn(II) aq promotes Ni exchange between Ni-substituted Manganite and dissolved Ni(II), with around 30% of Ni exchanged at pH 7.5 over the duration of the experiment. No new mineral phases are detected following recrystallization as determined by X-ray diffraction and XAS. Our results reveal that Mn(II)-catalyzed mineral recrystallization partitions Ni between Mn oxides and aqueous fluids and can therefore affect Ni speciation and mobility in the environment.

Dynamic coupled metal transport-speciation model: application to assess a zinc-contaminated lake.

PubMed

Bhavsar, Satyendra P; Diamond, Miriam L; Gandhi, Nilima; Nilsen, Joel

2004-10-01

A coupled metal transport and speciation/complexation model (TRANSPEC) has been developed to estimate the speciation and fate of multiple interconverting species in surface aquatic systems. Dynamic-TRANSPEC loosely, sequentially couples the speciation/complexation and fate modules that, for the unsteady state formulation, run alternatively at every time step. The speciation module first estimates species abundance using, in this version, MINEQL+ considering time-dependent changes in water and pore-water chemistry. The fate module is based on the quantitative water air sediment interaction (QWASI) model and fugacity/aquivalence formulation, with the option of using a pseudo-steady state solution to account for past discharges. Similarly to the QWASI model for organic contaminants, TRANSPEC assumes the instantaneous equilibrium distribution of metal species among dissolved, colloidal, and particulate phases based on ambient chemistry parameters that can be collected through conventional field methods. The model is illustrated with its application to Ross Lake (Manitoba, Canada) that has elevated Zn concentrations due to discharges over 70 years from a mining operation. Using measurements from field studies, the model reproduces year-round variations in Zn water concentrations. A 10-year projection for current conditions suggests decreasing Zn remobilization and export from the lake. Decreasing Zn loadings increases sediment-to-water transport but decreases water concentrations, and vice versa. Species distribution is affected by pH such that a decrease in pH increases metal export from the lake and vice versa.

Multi-trace element levels and arsenic speciation in urine of e-waste recycling workers from Agbogbloshie, Accra in Ghana.

PubMed

Asante, Kwadwo Ansong; Agusa, Tetsuro; Biney, Charles Augustus; Agyekum, William Atuobi; Bello, Mohammed; Otsuka, Masanari; Itai, Takaaki; Takahashi, Shin; Tanabe, Shinsuke

2012-05-01

To understand human contamination by multi-trace elements (TEs) in electrical and electronic waste (e-waste) recycling site at Agbogbloshie, Accra in Ghana, this study analyzed TEs and As speciation in urine of e-waste recycling workers. Concentrations of Fe, Sb, and Pb in urine of e-waste recycling workers were significantly higher than those of reference sites after consideration of interaction by age, indicating that the recycling workers are exposed to these TEs through the recycling activity. Urinary As concentration was relatively high, although the level in drinking water was quite low. Speciation analysis of As in human urine revealed that arsenobetaine and dimethylarsinic acid were the predominant As species and concentrations of both species were positively correlated with total As concentration as well as between each other. These results suggest that such compounds may be derived from the same source, probably fish and shellfish and greatly influence As exposure levels. To our knowledge, this is the first study on human contamination resulting from the primitive recycling of e-waste in Ghana. This study will contribute to the knowledge about human exposure to trace elements from an e-waste site in a less industrialized region so far scantly covered in the literature. Copyright © 2012 Elsevier B.V. All rights reserved.

Heavy metal speciation and uptake in crayfish and tadpoles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bundy, K.J.; Berzins, D.; Millet, L.

1996-12-31

Developing valid pollution recording methods is central to assessing environmental damage and remediation. This often is difficult, however, because of speciation and multiphase distribution of contaminants. Polarography, an electroanalytical technique capable of detection and quantification of trace levels of elements and ionic complexes, is a promising method for analyzing environmental samples. Here, polarography has been used to determine lead concentration in water, sediment, bullfrogs, tadpoles, and adsorbed onto kaolin. It has also been used to measure hexavalent chromium concentration in crayfish. This research involves field studies and two laboratory experiments. Studies of a Louisiana swamp have shown lead`s affinity formore » sediment and water particulate phases, rather than being ionically dissolved in the aqueous phase. In swamp bullfrogs, lead was found in greater concentrations in bone compared to muscle. In the first laboratory experiment, lead uptake originating from water and sediment increased in tadpoles as exposure time and concentration increased. Also, this animal`s development was hindered at higher concentrations. The second laboratory experiment exposed crayfish to aqueous hexavalent chromium. Total chromium uptake increased with exposure time and concentration. The chromium tissue abundance was hepatopancreas > gills > muscle. A substantial portion of tissue hexavalent chromium converted to the less toxic trivalent form.« less

Environmental variation between habitats and uptake of heavy metals by Urtica dioica.

PubMed

Otte, M L; Wijte, A H

1993-12-01

The observation from previous surveys, that Urtica dioica plants that had grown in metal contaminated soil in the floodplains of the former Rhine estuary in different habitats, but at comparable total soil metal concentrations, showed significant differences in tissue metal concentrations, led to the hypothesis that variation in other environmental characteristics than soil composition and chemical speciation of metals between habitats is also important in determining uptake and translocation of metals in plants. A field survey indicated that differences in root Cd, Cu and Zn concentrations might partly be explained by variation in speciation of metals in different habitats. However, shoot concentrations showed a different pattern that did not relate to variation in soil metal concentrations. In a habitat experiment Urtica dioica plants were grown in artificially contaminated soil in pots that were placed in the four habitats (grassland, pure reed, mixed reed, osier bed) that were also included in the field survey. After seven weeks the plants showed significant differences in Cu and Zn concentrations in roots and aboveground plant parts and in distribution of the metals in the plants between habitats. It was concluded that variation between habitats in environmental characteristics other than soil composition can explain as much variation in plants as can variation in soil metal concentrations and/or speciation. The implications for assessment of soil metal contamination and uptake by plants are discussed.

Iron Speciation in the Subtropical Waters East of New Zealand using Multi Detection Window CLE-AdCSV Titrations.

NASA Astrophysics Data System (ADS)

Chandrasekhar, Anoop; Sander, Sylvia; Milnes, Angie; Boyd, Philip

2015-04-01

Iron plays a significant role in the ocean productivity as a micro nutrient that facilitates the growth of marine phytoplankton and microbes. The bioavailability of iron in the ocean depends on it speciation. Iron is bio available in its dissolved form and about 99.9% of dissolved iron in seawater is organically complexed with natural ligands. The competitive ligand equilibration - adsorptive cathodic stripping voltammetry (CLE-AdCSV) is the widely used technique to examine Fe speciation. The method has its own limitations. The analytical window employed in this technique has a distinct impact on Fe speciation results (Buck, Moffett et al. 2012). Recently, (Pizeta, Sander et al. in preparation) have shown that the accuracy of complexometric titrations improve if multiple analytical windows (MAW) are solved as a united dataset. Several programs are now available that enable this approach with the KMS (Kineteql.xls , Hudson 2014), which is based on an Excel application based on speciation calculation (Hudson, Rue et al. 2003, Sander, Hunter et al. 2011), being one of them. In the present work, the unified MAW data analysis method is applied to determine iron speciation by CLE-AdCSV with salicyl aldoxime (SA) (Abualhaija and van den Berg 2014) in real seawater samples from the Spring bloom FeCycle III voyage, which took place in an anticyclonic eddy in subtropical waters east of New Zealand in spring 2012. Two different analytical windows (5 and 15µM SA) were applied to samples from depth profiles taken during this cruise. The data obtained was analysed using the program KMS (Kineteql.xls). Most samples only returned one Fe-binding ligands class. Higher ligand concentrations were observed in the upper water column and the stability constants were above 22 (e.g. 22.25 ± 0.21 for station 63). Our results will be discussed in the context of microbial community distribution as well as other biogeochemical parameters. Abualhaija, M. M. and C. M. G. van den Berg (2014). "Chemical speciation of iron in seawater using catalytic cathodic stripping voltammetry with ligand competition against salicylaldoxime." Marine Chemistry 164(0): 60-74. Buck, K. N., J. Moffett, K. A. Barbeau, R. M. Bundy, Y. Kondo and J. Wu (2012). "The organic complexation of iron and copper: an intercomparison of competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE-ACSV) techniques " Limnology and Oceanography: Methods 10: 496-515. Hudson, R. J. M., E. L. Rue and K. W. Bruland (2003). "Modeling Complexometric Titrations of Natural Water Samples." Environ. Sci. Tech. 37: 1553-1562. Pizeta, I., S. G. Sander, O. Baars, K. Buck, R. Bundy, G. Carrasco, P. Croot, C. Garnier, L. Gerringa, M. Gledhill, K. Hirose, D. R. Hudson, Y. Kondo-Jacquot, L. Laglera, D. Omanovic, M. Rijkenberg, B. Twining and M. Wells (in preparation). "Intercomparison of estimating metal binding ligand parameters from simulated titration data using different fitting approaches." for Limnology and Oceanography: Methods. Sander, S. G., K. A. Hunter, H. Harms and M. Wells (2011). "Numerical approach to speciation and estimation of parameters used in modeling trace metal bioavailability." Environmental Science and Technology 45(15): 6388-6395.

Living organisms as an alternative to hyphenated techniques for metal speciation. Evaluation of baker's yeast immobilized on silica gel for Hg speciation*1

NASA Astrophysics Data System (ADS)

Pérez-Corona, Teresa; Madrid-Albarrán, Yolanda; Cámara, Carmen; Beceiro, Elisa

1998-02-01

The use of living organisms for metal preconcentration and speciation is discussed. Among substrates, Saccharomyces cerevisiae baker's yeast has been successfully used for the speciation of mercury [Hg(II) and CH 3Hg +], selenium [Se(IV) and Se(VI)] and antimony [Sb(III) and Sb(V)]. To illustrate the capabilities of these organisms, the analytical performance of baker's yeast immobilized on silica gel for on-line preconcentration and speciation of Hg(II) and methylmercury is reported. The immobilized cells were packed in a PTFE microcolumn, through which mixtures of organic and inorganic mercury solutions were passed. Retention of inorganic and organic mercury solutions took place simultaneously, with the former retained in the silica and the latter on the yeast. The efficiency uptake for both species was higher than 95% over a wide pH range. The speciation was carried out by selective and sequential elution with 0.02 mol L -1 HCl for methylmercury and 0.8 mol L -1 CN - for Hg(II). This method allows both preconcentration and speciation of mercury. The preconcentration factors were around 15 and 100 for methylmercury and mercury(II), respectively. The method has been successfully applied to spiked sea water samples.

Selective determination of heavy metals (Cd, Pb, Cr) speciation forms from hortic anthrosols

NASA Astrophysics Data System (ADS)

Bulgariu, Dumitru; Bulgariu, Laura; Filipov, Feodor; Astefanei, Dan; Stoleru, Vasile

2010-05-01

In soils from glass houses, the speciation and inter-phases distribution processes of heavy metals have a particular dynamic, different in comparison with those from non-protected soils. The predominant distribution forms of heavy metals in such soils types are: complexes with low mass organic molecules, organic-mineral complexes, complexes with inorganic ligands (hydroxide-complexes, carbonate-complexes, sulphate-complexes, etc.) and basic salts. All of these have high stabilities in conditions of soils from glass houses, and in consequence, the separation and determination of speciation forms (which is directly connected with biodisponibility of heavy metals) by usual methods id very difficult and has a high uncertain degree. In this study is presented an original method for the selective separation and differentiation of speciation forms of heavy metals from glass houses soils, which is based by the combination of solid-liquid sequential extraction (SPE) with the extraction in aqueous polymer-inorganic salt two-phase systems (ABS). The soil samples used for this study have been sampled from three different locations (glass houses from Iasi, Barlad and Bacau - Romania) where the vegetables cultivation have been performed by three different technologies. In this way was estimated the applicability and the analytical limits of method proposed by as, in function of the chemical-mineralogical and physical-chemical characteristics of soils. As heavy metals have been studied cadmium, lead and chromium, all being known for their high toxicity. The procedure used for the selective separation and differentiation of speciation forms of heavy metals from glass houses soils has two main steps: (i) non-destructive separation of chemical-mineralogical associations and aggregates from soils samples - for this the separation method with heavy liquids (bromophorme) and isodynamic magnetic method have been used; (ii) sequential extraction of heavy metals from soil fractions separated in the first step, by using combined SPE-ABS procedure. For the preparation of combined extraction systems was used polyethylene glycol (with different molecular mass: 2000, 4000 and 8000). As phase-forming inorganic salts and as selective extracting agents we have used different usual inorganic reagents. The type and concentration of phase-forming salts have been selected in function of, both nature of extracted heavy metals and chemical-mineralogical characteristics of soil samples. The experimental parameters investigated in this study are: molecular mass of polyethylene glycol and the concentration of polymeric solutions, nature and concentration of phase-forming salts, nature and concentration of extracting agents, pH in extraction system phase, type of extracted heavy metals, type of speciation forms of heavy metals and their concentrations. All these factors can influence significantly the efficiency and the selectivity of separation process. The experimental results have indicate that the combined SPE-ABS extraction systems have better separation efficiency, in comparison with traditional SPE systems and ca realized a accurate discrimination between speciation forms of heavy metals from soils. Under these conditions, the estimation of inter-phases distribution and biodisponibility of heavy metals has a high precision. On the other hand, when the combined SPE-ABS systems are used, the concomitant extraction of the elements from the same geochemical association with studied heavy metals (inevitable phenomena in case of separation by SPE procedures) is significant diminished. This increases the separation selectivity and facilitated the more accurate determination of speciation forms concentration. By adequate selection of extraction conditions can be realized the selective separation of organic-mineral complexes, which will permit to perform detailed studies about the structure and chemical composition of these. Acknowledgments The authors would like to acknowledge the financial support from Romanian Ministry of Education and Research (Project PNCDI 2-D5 no. 51045/07 and project PNCDI 2 - D5 no. 52-141 / 2008).

Iron mineral structure, reactivity, and isotopic composition in a South Pacific Gyre ferromanganese nodule over 4 Ma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marcus, Matthew A.; Edwards, Katrina J.; Gueguen, Bleuenn

Deep-sea ferromanganese nodules accumulate trace elements from seawater and underlying sediment porewaters during the growth of concentric mineral layers over millions of years. These trace elements have the potential to record past ocean geochemical conditions. The goal of this study was to determine whether Fe mineral alteration occurs and how the speciation of trace elements responds to alteration over ~3.7Ma of marine ferromanganese nodule (MFN) formation, a timeline constrained by estimates from 9 Be/ 10 Be concentrations in the nodule material. We determined Fe-bearing phases and Fe isotope composition in a South Pacific Gyre (SPG) nodule. Specifically, the distribution patternsmore » and speciation of trace element uptake by these Fe phases were investigated. The time interval covered by the growth of our sample of the nodule was derived from 9 Be/ 10 Be accelerator mass spectrometry (AMS). The composition and distribution of major and trace elements were mapped at various spatial scales, using micro-X-ray fluorescence (μXRF), electron microprobe analysis (EMPA), and inductively coupled plasma mass spectrometry (ICP-MS). Fe phases were characterized by micro-extended X-ray absorption fine structure (μEXAFS) spectroscopy and micro-X-ray diffraction (μXRD). Speciation of Ti and V, associated with Fe, was measured using micro-X-ray absorption near edge structure (μXANES) spectroscopy. Iron isotope composition (δ 56/54 Fe) in subsamples of 1-3mm increments along the radius of the nodule was determined with multiple-collector ICP-MS (MC-ICP-MS). The SPG nodule formed through primarily hydrogeneous inputs at a rate of 4.0±0.4mm/Ma. The nodule exhibited a high diversity of Fe mineral phases: feroxyhite (δ-FeOOH), goethite (α-FeOOH), lepidocrocite (γ-FeOOH), and poorly ordered ferrihydrite-like phases. These findings provide evidence that Fe oxyhydroxides within the nodule undergo alteration to more stable phases over millions of years. Trace Ti and V were spatially correlated with Fe and found to be adsorbed to Fe-bearing minerals. Ti/Fe and V/Fe ratios, and Ti and V speciation, did not vary along the nodule radius. The δ 56/54 Fe values, when averaged over sample increments representing 0.25-0.75Ma, were homogeneous within uncertainty along the nodule radius, at -0.12±0.07‰ (2sd, n=10). Our results indicate that the Fe isotope composition of the nodule remained constant during nodule growth and that mineral alteration did not affect the primary Fe isotope composition of the nodule. Furthermore, the average δ 56/54 Fe value of -0.12‰ we find is consistent with Fe sourced from continental eolian particles (dust). Despite mineral alteration, the trace element partitioning of Ti and V, and Fe isotope composition, do not appear to change within the sensitivity of our measurements. These findings suggest that Fe oxyhydroxides within hydrogenetic ferromanganese nodules are out of geochemical contact with seawater once they are covered by subsequent concentric mineral layers. Even though Fe-bearing minerals are altered, trace element ratios, speciation and Fe isotope composition are preserved within the nodule.« less

Iron mineral structure, reactivity, and isotopic composition in a South Pacific Gyre ferromanganese nodule over 4 Ma

DOE PAGES

Marcus, Matthew A.; Edwards, Katrina J.; Gueguen, Bleuenn; ...

2015-09-05

Deep-sea ferromanganese nodules accumulate trace elements from seawater and underlying sediment porewaters during the growth of concentric mineral layers over millions of years. These trace elements have the potential to record past ocean geochemical conditions. The goal of this study was to determine whether Fe mineral alteration occurs and how the speciation of trace elements responds to alteration over ~3.7Ma of marine ferromanganese nodule (MFN) formation, a timeline constrained by estimates from 9 Be/ 10 Be concentrations in the nodule material. We determined Fe-bearing phases and Fe isotope composition in a South Pacific Gyre (SPG) nodule. Specifically, the distribution patternsmore » and speciation of trace element uptake by these Fe phases were investigated. The time interval covered by the growth of our sample of the nodule was derived from 9 Be/ 10 Be accelerator mass spectrometry (AMS). The composition and distribution of major and trace elements were mapped at various spatial scales, using micro-X-ray fluorescence (μXRF), electron microprobe analysis (EMPA), and inductively coupled plasma mass spectrometry (ICP-MS). Fe phases were characterized by micro-extended X-ray absorption fine structure (μEXAFS) spectroscopy and micro-X-ray diffraction (μXRD). Speciation of Ti and V, associated with Fe, was measured using micro-X-ray absorption near edge structure (μXANES) spectroscopy. Iron isotope composition (δ 56/54 Fe) in subsamples of 1-3mm increments along the radius of the nodule was determined with multiple-collector ICP-MS (MC-ICP-MS). The SPG nodule formed through primarily hydrogeneous inputs at a rate of 4.0±0.4mm/Ma. The nodule exhibited a high diversity of Fe mineral phases: feroxyhite (δ-FeOOH), goethite (α-FeOOH), lepidocrocite (γ-FeOOH), and poorly ordered ferrihydrite-like phases. These findings provide evidence that Fe oxyhydroxides within the nodule undergo alteration to more stable phases over millions of years. Trace Ti and V were spatially correlated with Fe and found to be adsorbed to Fe-bearing minerals. Ti/Fe and V/Fe ratios, and Ti and V speciation, did not vary along the nodule radius. The δ 56/54 Fe values, when averaged over sample increments representing 0.25-0.75Ma, were homogeneous within uncertainty along the nodule radius, at -0.12±0.07‰ (2sd, n=10). Our results indicate that the Fe isotope composition of the nodule remained constant during nodule growth and that mineral alteration did not affect the primary Fe isotope composition of the nodule. Furthermore, the average δ 56/54 Fe value of -0.12‰ we find is consistent with Fe sourced from continental eolian particles (dust). Despite mineral alteration, the trace element partitioning of Ti and V, and Fe isotope composition, do not appear to change within the sensitivity of our measurements. These findings suggest that Fe oxyhydroxides within hydrogenetic ferromanganese nodules are out of geochemical contact with seawater once they are covered by subsequent concentric mineral layers. Even though Fe-bearing minerals are altered, trace element ratios, speciation and Fe isotope composition are preserved within the nodule.« less

Micron to Mine: Synchrotron Science for Mineral Exploration, Production, and Remediation

NASA Astrophysics Data System (ADS)

Banerjee, N.; Van Loon, L.; Flynn, T.

2017-12-01

Synchrotron science for mineral exploration, production, and remediation studies is a powerful tool that provides industry with relevant micron to macro geochemical information. Synchrotron micro X-ray fluorescence (SR-µXRF) offers a direct, high-resolution, rapid, and cost-effective chemical analysis while preserving the context of the sample by mapping ore minerals with ppm detection limits. Speciation of trace and deleterious elements can then be probed using X-ray absorption near-edge structure (XANES) spectroscopy. Large-scale (tens of cm) µXRF mapping and XANES analysis of samples collected at various mine locations have been undertaken to address questions regarding mineralization history to develop novel trace element exploration vectors. This information provides integral insights into trace element associations with ore minerals, local redox conditions responsible for mineralization, and mineralizing mechanisms. Gold is commonly intimately associated with sulfide mineralization (e.g., pyrite, arsenopyrite, etc.) and is present both as inclusions and filling fractures in sulfide grains. Gold may also occur as nanoparticles and/or in the sulfide mineral crystal lattice, known as "invisible gold". Understanding the nature and distribution of invisible gold in ore is integral to processing efficiency. The high flux and energy of a synchrotron light source allows for the detection of invisible gold by µXRF, and can probe its nature (metallic Au0 vs. lattice bound Au1+) using XANES spectroscopy. The long-term containment and management of arsenic is necessary to protect the health of both humans and the environment. Understanding the relationship of arsenic mineralization to gold deposits can lead to more sophisticated planning for mineral processing and the eventual storage of gangue materials. µXANES spectroscopy is an excellent tool for determining arsenic speciation within the context of the sample. Mineral phases such as arsenopyrite, scorodite, and arsenic trioxide can be accurately identified as well as relative amounts determined. With this information the oxidation-reduction of arsenic-bearing compounds can be monitored to optimize management practices for the long-term capture of arsenic contaminants.

How Does Boiling in the Earth's Crust Influence Metal Speciation and Transport?

NASA Astrophysics Data System (ADS)

Kam, K.; Lemke, K.

2014-12-01

The presence of large quantities of precious metals, such as gold and copper, near the Earth's surface (upper crust) is commonly attributed to transport in aqueous solution and precipitation upon variations in temperature and pressure. As a consequence, gold exploration is closely linked to solution chemistry, i.e. hydrothermal processes involving aqueous fluids with densities of around unity. However, as crustal fluids buoyantly ascend, boiling produces a coexisting low-density aqueous liquid with fundamentally different physical and chemical properties, and a, most importantly, a high affinity for coinage metals (Heinrich et al., Econ Geol., 1992, 87, 1566). From recent experimental studies of Au (Hurtig and Williams-Jones, 2014, Geochim. Cosmochim. Acta,, 127, 304), we know that metal speciation in this low-density phase differs fundamentally from that observed in bulk solution, clearly, with important implications for Au, and metal speciation in general, transport and ore concentrations processes (these processes would also be operable in industrial geothermal plants given the quite special solvent properties of steam). In brief, this study focuses on the speciation of select metal halides in bulk solution as well as in water vapor, and is driven by our need to understand the solvent properties of around 2.0x109 cubic kilometers of free water (or 2,500 times as much water as stored in all lakes and rivers) present in the Earth's crust. The scope of this study has particular applications in the geothermal and oil industries, as both deal with high temperature low-density aqueous fluids. Understanding how metal halide species behave upon boiling can also provide insight into how metals, such as copper and silver, coat turbine equipment and steam piping in geothermal plants, ultimately rendering these components inoperable. This study will also provide preliminary results from mass spectrometric experiments of transition metal halides, and will be augmented with results from molecular simulations of metal halides that are aimed at characterizing the nature (i.e. relativistic structures and energies) of metal clusters in water vapor.

Inorganics in Organics: Tracking down the Intrinsic Equilibriums between Organic Molecules and Trace Elements in Oceanic Waters

NASA Astrophysics Data System (ADS)

Lechtenfeld, O. J.; Koch, B. P.; Kattner, G.

2010-12-01

Recent developments in analytical instrumentation enable to describe biogeochemical processes in oceanic waters on a molecular level. This is the prerequisite to integrate biological and geochemical parameters and to develop chemical cycles on a global perspective. The state-of-the-art Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) applications for dissolved organic matter (DOM) focus mainly on carbon, hydrogen, oxygen and nitrogen isotopes. Implementation of sulfur and especially phosphorus in the molecular formula assignment has been questionable because of ambiguous calculated elemental formulas. On the other hand, many compounds bearing these elements are well known to occur in the dissolved state as part of the permanent recycling processes (e.g. phospholipids, phosphonates) but analytics of dissolved organic phosphorus (DOP) and sulfur (DOS) are often hampered by the large inorganic P and S pools. Even less is known about complexation characteristics of the DOM moieties. Although electrochemical methods provide some information about trace metal speciation, the high amount of organic molecules and its insufficient description as chemical functional classes prevent the assignment of trace metals to ligand classes. Nevertheless, it is undoubtful that a varying but extensive amount of transition metals is bond in form of organic complexes. Hyphenation of reversed phase high performance liquid chromatography (RP-HPLC) with high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) is a valuable tool to study these metal-organic interactions in a qualitative and quantitative approach. We established a desolvation method that allows direct transfer of high organic solvent loads into the plasma. Thus, in combination with internal standardization and external calibration, the investigation of a broad polarity scale was possible. This approach overcomes previous restrictions to non-organic solvent separation techniques like size exclusion chromatography (SEC). We used solid phase extracted DOM (SPE-DOM) from Atlantic and Southern Ocean water samples to show that organic sulfur and phosphorus species can be separated via RP-HPLC and that the partitioning can be correlated to trace metal binding capabilities in the different fractions. A molecular level investigation of these fractions via FT-ICR-MS revealed further details of the complexation features and connects the polarity-based separation on a C18 column to O/C and H/C elemental ratios. With our study, we showed that biologically relevant transition metals (e.g. Fe, Ni, Cu) and uranium are intrinsic constituents of the DOM fractions. Moreover, a comparison between samples from different ecological provinces and diagenetic conditions was performed to highlight the benefits of this approach for future marine biogeochemical research.

Peat hybrid sorbents for treatment of wastewaters and remediation of polluted environment

NASA Astrophysics Data System (ADS)

Klavins, Maris; Burlakovs, Juris; Robalds, Artis; Ansone-Bertina, Linda

2015-04-01

For remediation of soils and purification of polluted waters, wastewaters, sorbents might be considered as an prospective group of materials and amongst them peat have a special role due to low cost, biodegradability, high number of functional groups, well developed surface area and combination of hydrophilic/hydrophobic structural elements. Peat as sorbent have good application potential for removal of trace metals, and we have demonstrated peat sorption capacities, sorption kinetics, thermodynamics in respect to metals with different valencies - Tl(I), Cu(II), Cr(III). However peat sorption capacity in respect to nonmetallic (anionic species) elements is low. Also peat mechanical properties do not support application in large scale column processes. To expand peat application possibilities the approach of biomass based hybrid sorbents has been elaborated. The concept "hybrid sorbent" in our understanding means natural, biomass based sorbent modified, covered with another sorbent material, thus combining two types of sorbent properties, sorbent functionalities, surface properties etc. As the "covering layer" both inorganic substances, mineral phases (iron oxohydroxides, oxyapatite) both organic polymers (using graft polymerization) were used. The obtained sorbents were characterised by their spectral properties, surface area, elemental composition. The obtained hybrid sorbents were tested for sorption of compounds in anionic speciation forms, for example of arsenic, antimony, tellurium and phosphorous compounds in comparison with weakly basic anionites. The highest sorption capacity was observed when peat sorbents modified with iron compounds were used. Sorption of different arsenic speciation forms onto iron-modified peat sorbents was investigated as a function of pH and temperature. It was established that sorption capacity increases with a rise in temperature, and the calculation of sorption process thermodynamic parameters indicates the spontaneity of sorption process and its endothermic nature. The recycling options of obtained compounds after their saturation with metal or non-metallic species are suggested. Acknowledgement: Support from a project 2014/0009/1DP/1.1.1.2.0/13/APIA/VIAA/044

Speciation of PM10 sources of airborne nonferrous metals within the 3-km zone of lead/zinc smelters.

PubMed

Batonneau, Yann; Bremard, Claude; Gengembre, Leon; Laureyns, Jacky; Le Maguer, Agnes; Le Maguer, Didier; Perdrix, Esperanza; Sobanska, Sophie

2004-10-15

The purpose of this study was to estimate the speciation of PM10 sources of airborne Pb, Zn, and Cd metals (PM10 is an aerosol standard of aerodynamic diameter less than 10 microm.) in the atmosphere of a 3 km zone surrounding lead/zinc facilities in operation for a century. Many powdered samples were collected in stacks of working units (grilling, furnace, and refinery), outdoor storages (ores, recycled materials), surrounding waste slag (4 Mt), and polluted topsoils (3 km). PM10 samples were generated from the raw powders by using artificial resuspension and collection devices. The bulk PM10 multielemental analyses were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). The proportions in mass of Pb (50%), Zn (40%), and Cd (1%) contents and associated metals (traces) reach the proportions of corresponding raw powdered samples of ores, recycled materials, and fumesize emissions of plants without specific enrichment. In contrast, Pb (8%) and Zn (15%) contents of PM10 of slag deposit were found to be markedly higher than those of raw dust, Pb (4%), and Zn (9%), respectively. In the same way, Pb (0.18%), Zn (0.20%), and Cd (0.004%) were enriched by 1.7, 2.1, and 2.3 times, respectively, in PM10 as compared with raw top-soil corresponding values. X-ray wavelength dispersive electron-microprobe (EM-WDS) microanalysis did not indicate well-defined phases or simple stoichiometries of all the PM10 samples atthe level of the spatial resolution (1 microm3). X-ray photoelectron spectroscopy (XPS) indicated that minor elements such as Cd, Hg, and C are more concentrated on the particle surface than in the bulk of PM10 generated by the smelting processes. (XPS) provided also the average speciation of the surface of PM10; Pb is mainly represented as PbSO4, Zn as ZnS, and Cd as CdS or CdSO4, and small amounts of coke were also detected. The speciation of bulk PM10 crystallized compounds was deduced from XRD diffractograms with a raw estimation of the relative quantities. PbS and ZnS were found to be the major phases in PM10 generated by the smelting facilities with PbSO4, PbSO4 x PbO, PbSO4 x 4PbO, Pb metal, and ZnO as minor phases. The slag waste PM10 was found to contain some amounts of PbCO3, PbSO4 x PbO, and ZnFe2O4 phases. The large heterogeneity at the level of the individual particle generates severe overlap of chemical information even at the microm scale using electron microprobe (WDS) and Raman microprobe techniques. Fortunately, scanning Raman microspectrometry combined with SIMPle-to-use Interactive Self-modeling Mixture Analysis (SIMPLISMA) performed the PM10 speciation at the level of individual particles. The speciation of major Pb, Zn, and Cd compounds of PM10 stack emissions and wind blown dust of ores and recycled materials were found to be PbSO4, PbSO4 x PbO, PbSO4 x 4PbO, PbO, metallic Pb, ZnS, ZnO, and CdS. The PM10 dust of slag waste was found to contain PbCO3, Pb(OH)2 x 2PbCO3, PbSO4 x PbO, and ZnS, while PM10-bound Pb, Zn of the top-soils contain Pb5(PO4)3Cl, ZnFe2O4 as well as Pb(II) and Zn(II) compounds adsorbed on Fe(III) oxides and in association with clays.

Distribution and solid-phase speciation of toxic heavy metals of bed sediments of Bharali tributary of Brahmaputra River.

PubMed

Hoque, Raza Rafiqul; Goswami, K G; Kusre, B C; Sarma, K P

2011-06-01

Heavy metal (Fe, Mn, Zn, Cu, Ni, Pb, and Cd) concentrations and their chemical speciations were investigated for the first time in bed sediments of Bharali River, a major tributary of the Brahmaputra River of the Eastern Himalayas. Levels of Fe, Mn, Pb, and Cd in the bed sediments were much below the average Indian rivers; however, Cu and Zn exhibit levels on the higher side. Enrichment factors (EF) of all metals was greater than 1 and a higher trend of EF was seen in the abandoned channel for most metals. Pb showed maximum EF of 32 at site near an urban center. The geoaccumulation indices indicate that Bharali river is moderately polluted. The metals speciations, done by a sequential extraction regime, show that Cd, Cu, and Pb exhibit considerable presence in the exchangeable and carbonate fraction, thereby showing higher mobility and bioavailability. On the other hand, Ni, Mn, and Fe exhibit greater presence in the residual fraction and Zn was dominant in the Fe-Mn oxide phase. Inter-species correlations at three sites did not show similar trends for metal pairs indicating potential variations in the contributing sources.

In-situ determination of metallic variation and multi-association in single particles by combining synchrotron microprobe, sequential chemical extraction and multivariate statistical analysis.

PubMed

Zhu, Yu-Min; Zhang, Hua; Fan, Shi-Suo; Wang, Si-Jia; Xia, Yi; Shao, Li-Ming; He, Pin-Jing

2014-07-15

Due to the heterogeneity of metal distribution, it is challenging to identify the speciation, source and fate of metals in solid samples at micro scales. To overcome these challenges single particles of air pollution control residues were detected in situ by synchrotron microprobe after each step of chemical extraction and analyzed by multivariate statistical analysis. Results showed that Pb, Cu and Zn co-existed as acid soluble fractions during chemical extraction, regardless of their individual distribution as chlorides or oxides in the raw particles. Besides the forms of Fe2O3, MnO2 and FeCr2O4, Fe, Mn, Cr and Ni were closely associated with each other, mainly as reducible fractions. In addition, the two groups of metals had interrelations with the Si-containing insoluble matrix. The binding could not be directly detected by micro-X-ray diffraction (μ-XRD) and XRD, suggesting their partial existence as amorphous forms or in the solid solution. The combined method on single particles can effectively determine metallic multi-associations and various extraction behaviors that could not be identified by XRD, μ-XRD or X-ray absorption spectroscopy. The results are useful for further source identification and migration tracing of heavy metals. Copyright © 2014 Elsevier B.V. All rights reserved.

Metal speciation in Julia Creek oil shale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirner, A.V.

1989-03-01

The concentrations of 19 elements were determined in organic and inorganic phases of the Julia Creek Oil Shale (Queensland/Australia). The phases were obtained by solvent and alkaline extractions as well as by stepwise demineralization with strong acids. Together with the results of other groups, a consistent model concerning the partition of trace elements in the various sedimentary components could be achieved. Whereas V, Ni and Ag show distributions comparable to the abundances of the correspondent phases in the sample, Ca, Mn and Co are concentrated in the mineral components, and B, As and Pb are enriched in kerogen. Al, Cr,more » Fe, Cu, Zn, Mo, Cd and Sb range between these extremes, while Au and Hg are contained in the humic substances only.« less

Arsenic speciation and spatial and interspecies differences of metal concentrations in mollusks and crustaceans from a South China estuary.

PubMed

Zhang, Wei; Wang, Wen-Xiong; Zhang, Li

2013-05-01

Arsenic speciation and concentrations were determined in mollusks and crustaceans in the intertidal zone from twelve locations in Zhanjiang estuary, South China. Metal concentrations (Ag, As, Cd, Cu, Hg, Ni, Pb, and Zn) were also concurrently determined in these species. Arsenic speciation analysis showed that the less-toxic arsenobetaine (AsB) constituted 80.6-98.8 % of all As compounds, and dimethylarsinic acid (DMA) constituted 0.47-3.44 %. Monomethylarsonic acid (MMA) and As(V) were only detected in the whelk Drupa fiscella and the crab Heteropilumnus ciliatus, respectively. Arsenite [As(III)] was not detected in any of the sampled specimens, but there were also unidentified other As species. A strong spatial variation of metals in the oyster Saccostrea cucullata was found in the estuary, confirming that oysters can be used as a good biomonitor of metal contamination in the studied area. The concentrations of eight metals in the studied mollusks and crustaceans clearly revealed that these invertebrates accumulated different metals to different degrees. Furthermore, As, Cd, Cu, Hg, and Pb contents in mollusks and crustacean samples were below the Food and Agricultural Organization (FAO) safe concentrations, thus there was no obvious health risk from the intake of the metals through marine mollusks and crustaceans consumption.

Defense Coastal/Estuarine Research Program (DCERP) Baseline Monitoring Plan

DTIC Science & Technology

2007-09-19

climatological stress (e.g., temperature, drought) and shorter-term air pollutant stress (oxidants and metals ). Heavy metals of fine PM have been...speciation of the fine and coarse PM fractions will allow distinction between different PM sources such as wind blown soil dust, including dust...emitting 12% of the total PM2.5 mass (U.S. EPA, 2004b). Source apportionment modeling of PM2.5 mass concentrations from 24 Speciation Defense Coastal

Evolution of Metallic Trace Elements in Contaminated River Sediments: Geochemical Variation Along River Linear and Vertical Profile

NASA Astrophysics Data System (ADS)

Kanbar, Hussein; Montarges-Pelletier, Emmanuelle; Mansuy-Huault, Laurence; Losson, Benoit; Manceau, Luc; Bauer, Allan; Bihannic, Isabelle; Gley, Renaud; El Samrani, Antoine; Kobaissi, Ahmad; Kazpard, Veronique; Villieras, Frédéric

2015-04-01

Metal pollution in riverine systems poses a serious threat that jeopardizes water and sediment quality, and hence river dwelling biota. Since those metallic pollutants can be transported for long distances via river flow, river management has become a great necessity, especially in times where industrial activities and global climate change are causing metal release and spreading (by flooding events). These changes are able to modify river hydrodynamics, and as a consequence natural physico-chemical status of different aquatic system compartments, which in turn alter metal mobility, availability and speciation. Vertical profiles of sediments hold the archive of what has been deposited for several tenths of years, thus they are used as a tool to study what had been deposited in rivers beds. The studied area lies in the Orne river, northeastern France. This river had been strongly modified physically and affected by steelmaking industrial activities that had boosted in the middle of the last century. This study focuses on several sites along the linear of the Orne river, as well as vertical profiles of sediments. Sediment cores were collected at sites where sedimentation is favoured, and in particular upstream two dams, built in the second half of the XXth century for industrial purposes. Sediment cores were sliced into 2-5cm layers, according to suitability, and analysed for physical and physico-chemical properties, elemental content and mineralogy. Data of the vertical profile in a sediment core is important to show the evolution of sediments as a function of depth, and hence age, in terms of nature, size and constituents. The physical properties include particle size distribution (PSD) and water content. In addition, the physico-chemical properties, such as pH and oxido-reduction potential (ORP) of interstitial water from undisturbed cores were also detected. Total elemental content of sediment and available ones of extracted interstitial waters was detected using ICP-MS and ICP-OES for trace and major elements respectively. Well crystallized minerals were detected by X-Ray Diffraction (XRD), while amorphous and poorly crystallized phases were identified with scanning and transmission electron microscope (SEM and TEM respectively), combined with Energy Dispersive X-Ray Spectroscopy (EDXS). Such microscopic techniques also provided information about metal carriers. To have an insight about the metal speciation at molecular level, X-Ray Absorption spectroscopy (XAS) was performed at Zn K-edge. The first analyses of Orne sediment cores evidenced different particle size distribution and sediment consolidation levels. Yet the cores showed that below a layer of apparently recent sediments (about 10-20 cm), lie highly contaminated ones. Zn and Pb content in deep sediment layers reach several thousands ppm, where they appeared mainly as Zn and Pb sulphides. Also, the high content of iron in deep sediments resulted in the presence of different iron phases: hematite, wuestite, magnetite, goethite, sulphides (pyrite), as well as undefined iron-silicate. In addition, interstitial waters contained high values of available metals (Zn: 500-35000 ppm, Pb: 150-5700 ppm, Cd: 1-10ppm), which might cause a greater concern than solid-bound metals, especially when river bed sediments are disturbed.

Applications of time-resolved laser fluorescence spectroscopy to the environmental biogeochemistry of actinides.

PubMed

Collins, Richard N; Saito, Takumi; Aoyagi, Noboru; Payne, Timothy E; Kimura, Takaumi; Waite, T David

2011-01-01

Time-resolved laser fluorescence spectroscopy (TRLFS) is a useful means of identifying certain actinide species resulting from various biogeochemical processes. In general, TRLFS differentiates chemical species of a fluorescent metal ion through analysis of different excitation and emission spectra and decay lifetimes. Although this spectroscopic technique has largely been applied to the analysis of actinide and lanthanide ions having fluorescence decay lifetimes on the order of microseconds, such as UO , Cm, and Eu, continuing development of ultra-fast and cryogenic TRLFS systems offers the possibility to obtain speciation information on metal ions having room-temperature fluorescence decay lifetimes on the order of nanoseconds to picoseconds. The main advantage of TRLFS over other advanced spectroscopic techniques is the ability to determine in situ metal speciation at environmentally relevant micromolar to picomolar concentrations. In the context of environmental biogeochemistry, TRLFS has principally been applied to studies of (i) metal speciation in aqueous and solid phases and (ii) the coordination environment of metal ions sorbed to mineral and bacterial surfaces. In this review, the principles of TRLFS are described, and the literature reporting the application of this methodology to the speciation of actinides in systems of biogeochemical interest is assessed. Significant developments in TRLFS methodology and advanced data analysis are highlighted, and we outline how these developments have the potential to further our mechanistic understanding of actinide biogeochemistry. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

The importance of ligand speciation in environmental research: a case study.

PubMed

Sillanpää, M; Orama, M; Rämö, J; Oikari, A

2001-02-21

The speciations of EDTA and DTPA in process, waste and river waters are modelled and simulated, specifically to the mode of occurrence in the pulp and paper mill effluents and subsequently in receiving waters. Due to relatively short residence times in bleaching process and waste water treatment and slow exchange kinetics, it is expected that the thermodynamic equilibrium is not necessarily reached. Therefore, the initial speciation plays a key role. As such, the simulations have been extended to the process waters of the pulp and paper industry taking into account estimated average conditions. The results reveal that the main species are; Mn and Ca complexes of EDTA and DTPA in pulp mill process waters; Fe(III) and Mn complexes of EDTA and DTPA in waste waters; Fe(III) and Zn complexes of EDTA and DTPA in receiving waters. It is also shown how the increasing concentration of complexing agents effects the speciation. Alkaline earth metal chelation plays a significant role in the speciation of EDTA and DTPA when there is a noticeable molar excess of complexing agents compared with transition metals.

Trace Elements in River Waters

NASA Astrophysics Data System (ADS)

Gaillardet, J.; Viers, J.; Dupré, B.

2003-12-01

Trace elements are characterized by concentrations lower than 1 mg L-1 in natural waters. This means that trace elements are not considered when "total dissolved solids" are calculated in rivers, lakes, or groundwaters, because their combined mass is not significant compared to the sum of Na+, K+, Ca2+, Mg2+, H4SiO4, HCO3-, CO32-, SO42-, Cl-, and NO3-. Therefore, most of the elements, except about ten of them, occur at trace levels in natural waters. Being trace elements in natural waters does not necessarily qualify them as trace elements in rocks. For example, aluminum, iron, and titanium are major elements in rocks, but they occur as trace elements in waters, due to their low mobility at the Earth's surface. Conversely, trace elements in rocks such as chlorine and carbon are major elements in waters.The geochemistry of trace elements in river waters, like that of groundwater and seawater, is receiving increasing attention. This growing interest is clearly triggered by the technical advances made in the determination of concentrations at lower levels in water. In particular, the development of inductively coupled plasma mass spectrometry (ICP-MS) has considerably improved our knowledge of trace-element levels in waters since the early 1990s. ICP-MS provides the capability of determining trace elements having isotopes of interest for geochemical dating or tracing, even where their dissolved concentrations are extremely low.The determination of trace elements in natural waters is motivated by a number of issues. Although rare, trace elements in natural systems can play a major role in hydrosystems. This is particularly evident for toxic elements such as aluminum, whose concentrations are related to the abundance of fish in rivers. Many trace elements have been exploited from natural accumulation sites and used over thousands of years by human activities. Trace elements are therefore highly sensitive indexes of human impact from local to global scale. Pollution impact studies require knowledge of the natural background concentrations and knowledge of pollutant behavior. For example, it is generally accepted that rare earth elements (REEs) in waters behave as good analogues for the actinides, whose natural levels are quite low and rarely measured. Water quality investigations have clearly been a stimulus for measurement of toxic heavy metals in order to understand their behavior in natural systems.From a more fundamental point of view, it is crucial to understand the behavior of trace elements in geological processes, in particular during chemical weathering and transport by waters. Trace elements are much more fractionated by weathering and transport processes than major elements, and these fractionations give clues for understanding the nature and intensity of the weathering+transport processes. This has not only applications for weathering studies or for the past mobilization and transport of elements to the ocean (potentially recorded in the sediments), but also for the possibility of better utilization of trace elements in the aqueous environment as an exploration tool.In this chapter, we have tried to review the recent literature on trace elements in rivers, in particular by incorporating the results derived from recent ICP-MS measurements. We have favored a "field approach" by focusing on studies of natural hydrosystems. The basic questions which we want to address are the following: What are the trace element levels in river waters? What controls their abundance in rivers and fractionation in the weathering+transport system? Are trace elements, like major elements in rivers, essentially controlled by source-rock abundances? What do we know about the chemical speciation of trace elements in water? To what extent do colloids and interaction with solids regulate processes of trace elements in river waters? Can we relate the geochemistry of trace elements in aquatic systems to the periodic table? And finally, are we able to satisfactorily model and predict the behavior of most of the trace elements in hydrosystems?An impressive literature has dealt with experimental works on aqueous complexation, uptake of trace elements by surface complexation (inorganic and organic), uptake by living organisms (bioaccumulation) that we have not reported here, except when the results of such studies directly explain natural data. As continental waters encompass a greater range of physical and chemical conditions, we focus on river waters and do not discuss trace elements in groundwaters, lakes, and the ocean. In lakes and in the ocean, the great importance of life processes in regulating trace elements is probably the major difference from rivers.Section 5.09.2 of this chapter reports data. We will review the present-day literature on trace elements in rivers to show that our knowledge is still poor. By comparing with the continental abundances, a global mobility index is calculated for each trace element. The spatial and temporal variability of trace-element concentrations in rivers will be shown to be important. In Section 5.09.3, sources of trace elements in river waters are indicated. We will point out the great diversity of sources and the importance of global anthropogenic contamination for a number of elements. The question of inorganic and organic speciation of trace elements in river water will then be addressed in Section 5.09.4, considering some general relationships between speciation and placement in the periodic table. In Section 5.09.5, we will show that studies on organic-rich rivers have led to an exploration of the "colloidal world" in rivers. Colloids are small particles, passing through the conventional filters used to separate dissolved and suspended loads in rivers. They appear as major carriers of trace elements in rivers and considerably complicate aqueous-speciation calculation. Finally, in Section 5.09.6, the significance of interactions between solutes and solid surfaces in river waters will be reviewed. Regulation by surfaces is of major importance for a great range of elements. Although for both colloids and surface interactions, some progress has been made, we are still far from a unified model that can accurately predict trace-element concentrations in natural water systems. This is mainly due to our poor physical description of natural colloids, surface site complexation, and their interaction with solutes.

Metalloids, soil chemistry and the environment.

PubMed

Lombi, Enzo; Holm, Peter E

2010-01-01

This chapter reviews physical chemical properties, origin and use ofmetalloids and their relevance in the environment. The elements boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), polonium (Po) and astatine (At) are considered metalloids. Metalloids conduct heat and electricity intermediate between nonmetals and metals and they generally form oxides. The natural abundance ofmetalloids varies from Si being the second most common element in the Earth's crust to At as the rarest of natural elements on Earth. The metalloid elements Ge, Te, Po and At are normally present in trace or ultratrace levels in the environment and as such are not considered of relevance in terms of environmental health. The environmental geochemical processes, factors and parameters controlling the partitioning and the speciation of B, Si, As and Sb are reviewed in relation to the bioavailability of these metalloids. Approaches based on the hypothesis that metal toxicity is related to both the metal-ligand complexation processes and the metal interactions with competing cations at the cell surface (biotic ligand) have so far not been successful for assessing metalloid bioavailability. The chapter concludes that our understanding of metalloids toxicity will improve in the future if, in addition to the points discussed above, surface membrane potentials are considered. This should represent a robust approach to the prediction of metalloid toxicity.

Speciation and isotopic exchangeability of nickel in soil solution.

PubMed

Nolan, Annette L; Ma, Yibing; Lombi, Enzo; McLaughlin, Mike J

2009-01-01

Knowledge of trace metal speciation in soil pore waters is important in addressing metal bioavailability and risk assessment of contaminated soils. In this study, free Ni(2+) activities were determined in pore waters of long-term Ni-contaminated soils using a Donnan dialysis membrane technique. The pore water free Ni(2+) concentration as a percentage of total soluble Ni ranged from 21 to 80% (average 53%), and the average amount of Ni bound to dissolved organic matter estimated by Windermere Humic Aqueous Model VI was < or = 17%. These data indicate that complexed forms of Ni can constitute a significant fraction of total Ni in solution. Windermere Humic Aqueous Model VI provided reasonable estimates of free Ni(2+) fractions in comparison to the measured fractions (R(2) = 0.83 with a slope of 1.0). Also, the isotopically exchangeable pools (E value) of soil Ni were measured by an isotope dilution technique using water extraction, with and without resin purification, and 0.1 mol L(-1) CaCl(2) extraction, and the isotopic exchangeability of Ni species in soil water extracts was investigated. The concentrations of isotopically non-exchangeable Ni in water extracts were <9% of total water soluble Ni concentrations for all soils. The resin E values expressed as a percentage of the total Ni concentrations in soil showed that the labile Ni pool ranged from 0.9 to 32.4% (average 12.4%) of total soil Ni. Therefore the labile Ni pool in these well-equilibrated contaminated soils appears to be relatively small in relation to total Ni concentrations.

Chemical speciation and recovery of gold(I, III) from wastewater and silver by liquid-liquid extraction with the ion-pair reagent amiloride mono hydrochloride and AAS determination.

PubMed

El-Shahawi, M S; Bashammakh, A S; Bahaffi, S O

2007-06-15

A novel and low cost liquid-liquid extraction procedure for the separation of gold(III) at trace level from aqueous medium of pH 5-9 has been developed. The method has been based upon the formation of a yellow colored ternary complex ion associate of tetrachloro gold(III) complex anion, AuCl(4)(-) with the ion-pair reagent 1-(3,5-diamino-6-chloropyrazinecarboxyl) guanidine hydrochloride monohydrate, namely amiloride, DPG(+).Cl(-). The effect of various parameters, e.g. pH, organic solvent, shaking time, etc. on the preconcentration of gold(III) from the aqueous media by the DPG(+).Cl(-) reagent has been investigated. The colored gold species was quantitatively extracted into 4-methyl pentan-2-one. The chemical composition of the ion associate of DPG(+).Cl(-) with AuCl(4)(-) in the organic solvent has been determined by the Job's method. The molar absorptivity (2.19x10(4)Lmol(-1)cm(-1)) of the associate DPG(+).AuCl(4)(-) at 362nm enabled a convenient application of the developed extraction procedure for the separation and AAS determination of traces of aurate ions. Mono-valence gold ions after oxidation to gold(III) with bromine water in HCl (1.0molL(-1)) media have been also extracted quantitatively from the aqueous media by the developed procedure. The chemical speciation of mono- and/or tri-valence gold species spiked to fresh and industrial wastewater samples has been achieved. The method has been also applied successfully from the separation of gold(I) and gold(III) species from metallic ions and silver. The developed method has also the advantage of freedom from most diverse ions.

Uranium speciation in biofilms studied by laser fluorescence techniques.

PubMed

Arnold, Thuro; Grossmann, Kay; Baumann, Nils

2010-03-01

Biofilms may immobilize toxic heavy metals in the environment and thereby influence their migration behaviour. The mechanisms of these processes are currently not understood, because the complexity of such biofilms creates many discrete geochemical microenvironments which may differ from the surrounding bulk solution in their bacterial diversity, their prevailing geochemical properties, e.g. pH and dissolved oxygen concentration, the presence of organic molecules, e.g. metabolites, and many more, all of which may affect metal speciation. To obtain such information, which is necessary for performance assessment studies or the development of new cost-effective strategies for cleaning waste waters, it is very important to develop new non-invasive methods applicable to study the interactions of metals within biofilm systems. Laser fluorescence techniques have some superior features, above all very high sensitivity for fluorescent heavy metals. An approach combining confocal laser scanning microscopy and laser-induced fluorescence spectroscopy for study of the interactions of biofilms with uranium is presented. It was found that coupling these techniques furnishes a promising tool for in-situ non-invasive study of fluorescent heavy metals within biofilm systems. Information on uranium speciation and uranium redox states can be obtained.

Concentrations and speciation of heavy metals in sludge from nine textile dyeing plants.

PubMed

Liang, Xin; Ning, Xun-an; Chen, Guoxin; Lin, Meiqing; Liu, Jingyong; Wang, Yujie

2013-12-01

The safe disposal of sludge from textile dyeing industry requires research on bioavailability and concentration of heavy metals. In this study, concentrations and chemical speciation of heavy metals (Cd, Cr, Cu, Ni, Zn, Pb) in sludge from nine different textile dyeing plants were examined. Some physiochemical features of sludge from textile dyeing industry were determined, and a sequential extraction procedure recommended by the Community Bureau of Reference (BCR) was used to study the metal speciation. Cluster analysis (CA) and principal component analysis (PCA) were applied to provide additional information regarding differences in sludge composition. The results showed that Zn and Cu contents were the highest, followed by Ni, Cr, Cd and Pb. The concentration of Cd and Ni in some sludge samples exceeded the standard suggested for acidic soils in China (GB18918-2002). In sludge from textile dyeing plants, Pb, Cd and Cr were principally distributed in the oxidizable and residual fraction, Cu in the oxidizable fraction, Ni in all four fractions and Zn in the acid soluble/exchangeable and reducible fractions. The pH and heat-drying method affected the fractionation of heavy metals in sludge. © 2013 Elsevier Inc. All rights reserved.

Uncertainty analysis of the nonideal competitive adsorption-donnan model: effects of dissolved organic matter variability on predicted metal speciation in soil solution.

PubMed

Groenenberg, Jan E; Koopmans, Gerwin F; Comans, Rob N J

2010-02-15

Ion binding models such as the nonideal competitive adsorption-Donnan model (NICA-Donnan) and model VI successfully describe laboratory data of proton and metal binding to purified humic substances (HS). In this study model performance was tested in more complex natural systems. The speciation predicted with the NICA-Donnan model and the associated uncertainty were compared with independent measurements in soil solution extracts, including the free metal ion activity and fulvic (FA) and humic acid (HA) fractions of dissolved organic matter (DOM). Potentially important sources of uncertainty are the DOM composition and the variation in binding properties of HS. HS fractions of DOM in soil solution extracts varied between 14 and 63% and consisted mainly of FA. Moreover, binding parameters optimized for individual FA samples show substantial variation. Monte Carlo simulations show that uncertainties in predicted metal speciation, for metals with a high affinity for FA (Cu, Pb), are largely due to the natural variation in binding properties (i.e., the affinity) of FA. Predictions for metals with a lower affinity (Cd) are more prone to uncertainties in the fraction FA in DOM and the maximum site density (i.e., the capacity) of the FA. Based on these findings, suggestions are provided to reduce uncertainties in model predictions.

Trace Metals and Nutrients at the Soil-Root Interface of Forest Soils

NASA Astrophysics Data System (ADS)

Courchesne, F.; Seguin, V.; Legrand, P.; Cloutier-Hurteau, B.

2004-05-01

The activity of roots creates a microenvironment, known as the rhizosphere, where soil properties, processes and feedback mechanisms differ substantially from those observed in the soil matrix. Due to its proximity to the site of elemental uptake by plants, the rhizosphere is viewed as a biogeochemical hotspot characterized by massive fluxes of matter and energy. In this context, the acquisition of new knowledge on the rhizosphere is crucial to increase our capacity to understand, manage and model soil-plants systems. Of particular interest to scientists is the response of the rhizosphere to perturbations of natural (e.g. climatic fluctuations) or anthropogenic (e.g. soil contamination) origin. Moreover, results from rhizosphere research help define new approaches designed either to restrict the entrance of potentially toxic elements in crops and, hence, in the food chain or, contrarily, to increase the uptake of trace elements by plants in contaminated environments to be bioremediated. Our recent studies in forested environments have clearly established that the rhizosphere (Abies, Acer, Betula, Picea, Pinus or Populus roots) is more acidic than the soil matrix and that it is enriched in organic substances (dissolved and solid), nutrient cations (Ca, Mg) and trace metals. Indeed, the rhizosphere systematically acts as a sink for Cd, Cu, Ni, Pb and Zn, notably under bioavailable (water-soluble and salt-extractable) forms. Yet, the relative activity of free metal ions is lower in the rhizosphere, as shown for Cu++, probably as a consequence of the higher DOC content. The corrosive environment forming in the rhizosphere, as controlled by the release of H+ ions and of organic acids, also impacts on mineral assemblages through an increase in the weathering of primary minerals (amphiboles, plagioclases) and the formation of secondary solid phases such as Fe and Al oxides. Some of the research avenues currently investigated by our research group include the quantification of functional links between organic carbon, microbial activity and metal speciation, the development of methodological and analytical approaches operating at the spatial scale of the rhizosphere and, the assessment of preferential hydrological fluxes along root networks.

The role of arbuscular mycorrhiza on change of heavy metal speciation in rhizosphere of maize in wastewater irrigated agriculture soil.

PubMed

Huang, Yi; Tao, Shu; Chen, You-jian

2005-01-01

To understand the roles of mycorrhiza in metal speciation in the rhizosphere and the impact on increasing host plant tolerance against excessive heavy metals in soil, maize (Zea mays L.) inoculated with arbuscular mycorrhizal fungus (Glomus mosseae) was cultivated in heavy metal contaminated soil. Speciations of copper, zinc and lead in the soil were analyzed with the technique of sequential extraction. The results showed that, in comparison to the bolked soil, the exchangeable copper increased from 26% to 43% in non-infected and AM-infected rhizoshpere respectively; while other speciation (organic, carbonate and Fe-Mn oxide copper) remained constant and the organic bound zinc and lead also increased but the exchangeable zinc and lead were undetectable. The organic bound copper, zinc and lead were higher by 15%, 40% and 20%, respectively, in the rhizosphere of arbuscular mycorrhiza infected maize in comparison to the non-infected maize. The results might indicate that mycorrhiza could protect its host plants from the phytotoxicity of excessive copper, zinc and lead by changing the speciation from bio-available to the non-bio-available form. The fact that copper and zinc accumulation in the roots and shoots of mycorrhia infected plants were significantly lower than those in the non-infected plants might also suggest that mycorrhiza efficiently restricted excessive copper and zinc absorptions into the host plants. Compared to the non-infected seedlings, the lead content of infected seedlings was 60% higher in shoots. This might illustrate that mycorrhiza have a different mechanism for protecting its host from excessive lead phytotoxicity by chelating lead in the shoots.

Arsenic, Antimony, Chromium, and Thallium Speciation in Water and Sediment Samples with the LC-ICP-MS Technique

PubMed Central

Jabłońska-Czapla, Magdalena

2015-01-01

Chemical speciation is a very important subject in the environmental protection, toxicology, and chemical analytics due to the fact that toxicity, availability, and reactivity of trace elements depend on the chemical forms in which these elements occur. Research on low analyte levels, particularly in complex matrix samples, requires more and more advanced and sophisticated analytical methods and techniques. The latest trends in this field concern the so-called hyphenated techniques. Arsenic, antimony, chromium, and (underestimated) thallium attract the closest attention of toxicologists and analysts. The properties of those elements depend on the oxidation state in which they occur. The aim of the following paper is to answer the question why the speciation analytics is so important. The paper also provides numerous examples of the hyphenated technique usage (e.g., the LC-ICP-MS application in the speciation analysis of chromium, antimony, arsenic, or thallium in water and bottom sediment samples). An important issue addressed is the preparation of environmental samples for speciation analysis. PMID:25873962

Parapatric speciation in three islands: dynamics of geographical configuration of allele sharing

PubMed Central

Iwasa, Yoh

2017-01-01

We studied the time to speciation by geographical isolation for a species living on three islands connected by rare migration. We assumed that incompatibility was controlled by a number of quantitative loci and that individuals differing in loci by more than a threshold did not mix genetically with each other. For each locus, we defined the geographical configuration (GC), which specifies islands with common alleles, and traced the stochastic transitions between different GCs. From these results, we calculated the changes in genetic distances. As a single migration event provides an opportunity for transitions in multiple loci, the GCs of different loci are correlated, which can be evaluated by constructing the stochastic differential equations of the number of loci with different GCs. Our model showed that the low number of incompatibility loci facilitates parapatric speciation and that migrants arriving as a group shorten the waiting time to speciation compared with the same number of migrants arriving individually. We also discuss how speciation rate changes with geographical structure. PMID:28386439

Heavy metals and its chemical speciation in sewage sludge at different stages of processing.

PubMed

Tytła, Malwina; Widziewicz, Kamila; Zielewicz, Ewa

2016-01-01

The analysis of heavy metal concentrations and forms in sewage sludge constitutes an important issue in terms of both health and environmental hazards the metals pose. The total heavy metals concentration enables only the assessment of its contamination. Hence the knowledge of chemical forms is required to determine their environmental mobility and sludge final disposal. Heavy metals speciation was studied by using four-stage sequential extraction BCR (Community Bureau of Reference). This study was aimed at determining the total concentration of selected heavy metals (Zn, Cu, Ni, Pb, Cd, Cr and Hg) and their chemical forms (except for Hg) in sludge collected at different stages of its processing at two municipal Wastewater Treatment Plants in southern Poland. Metals contents in sludge samples were determined by using flame atomic absorption spectrometry (FAAS) and electrothermal atomic absorption spectrometry (ETAAS). This study shows that Zn and Cu appeared to be the most abundant in sludge, while Cd and Hg were in the lowest concentrations. The sewage sludge revealed the domination of immobile fractions over the mobile ones. The oxidizable and residual forms were dominant for all the heavy metals. There was also a significant difference in metals speciation between sludges of different origin which was probably due to differences in wastewater composition and processes occurring in biological stage of wastewater treatment. The results indicate a negligible capability of metals to migrate from sludge into the environment. Our research revealed a significant impact of thickening, stabilization and hygienization on the distribution of heavy metals in sludge and their mobility.

The influence of avian biovectors on mercury speciation in a bog ecosystem.

PubMed

Kickbush, Jocelyn C; Mallory, Mark L; Murimboh, John D; Rand, Jennie; Klapstein, Sara J; Loder, Amanda L; Hill, Nicholas M; O'Driscoll, Nelson J

2018-05-08

Methylmercury (MeHg) is a neurotoxin and endocrine disruptor that bioaccumulates and biomagnifies through trophic levels, resulting in potentially hazardous concentrations. Although wetlands are known hotspots for mercury (Hg) methylation, the effects of avian biovectors on these processes are poorly understood. We examined Hg speciation and distribution in shallow groundwater and surface water from a raised-bog with over 30years of avian biovector (herring gulls Larus argentatus and great black-backed gulls Larus marinus) colonization and guano input. Compared to the reference site, the avian-impacted bog had elevated concentrations of total dissolved organic carbon (TOC), total Hg, MeHg, phosphate (PO 4 3- ), and other trace metals, notably Pb, As, Cd and Ni. Spatial interpolation showed that the densest area of gull nesting was co-located with areas that had the highest concentrations of PO 4 3- , MeHg, As and Cd, but not total mercury (THg), and models suggested that Mn, PO 4 3- , and dissolved TOC were strong predictors of MeHg. Our findings suggest that while these gulls may not be a significant source of Hg, the excess of PO 4 3- (a well recognised component of guano) and the subsequent changes in water chemistry due to avian biovector subsidies may increase net Hg methylation. Copyright © 2018 Elsevier B.V. All rights reserved.

Diminished Metal Accumulation in Riverine Fishes Exposed to Acid Mine Drainage over Five Decades

PubMed Central

Jeffree, Ross A.; Markich, Scott J.; Twining, John R.

2014-01-01

Bony bream (Nematalosa erebi) and black catfish (Neosilurus ater) were sampled from the fresh surface waters of the Finniss River in tropical northern Australia, along a metal pollution gradient draining the Rum Jungle copper/uranium mine, a contaminant source for over five decades. Paradoxically, populations of both fish species exposed to the highest concentrations of mine-related metals (cobalt, copper, lead, manganese, nickel, uranium and zinc) in surface water and sediment had the lowest tissue (bone, liver and muscle) concentrations of these metals. The degree of reduction in tissue concentrations of exposed populations was also specific to each metal and inversely related to its degree of environmental increase above background. Several explanations for diminished metal bioaccumulation in fishes from the contaminated region were evaluated. Geochemical speciation modeling of metal bioavailability in surface water showed no differences between the contaminated region and the control sites. Also, the macro-nutrient (calcium, magnesium and sodium) water concentrations, that may competitively inhibit metal uptake, were not elevated with trace metal contamination. Reduced exposure to contaminants due to avoidance behavior was unlikely due to the absence of refugial water bodies with the requisite metal concentrations lower than the control sites and very reduced connectivity at time of sampling. The most plausible interpretation of these results is that populations of both fish species have modified kinetics within their metal bioaccumulation physiology, via adaptation or tolerance responses, to reduce their body burdens of metals. This hypothesis is consistent with (i) reduced tissue concentrations of calcium, magnesium and sodium (macro-nutrients), in exposed populations of both species, (ii) experimental findings for other fish species from the Finniss River and other contaminated regions, and (iii) the number of generations exposed to likely selection pressure over 50 years. PMID:24663964

METHODS FOR THE SPECIATION OF METALS IN SOILS: A REVIEW

EPA Science Inventory

The inability to determine metal species in soils hampers efforts to understand the mobility, bioavailability, and fate of contaminant metals in environmental systems, to assess health risks posed by them, and to develop methods to remediate metal contaminated sites. Fortunately,...

METAL SPECIATION IN SOIL, SEDIMENT, AND WATER SYSTEMS VIA SYNCHROTRON RADIATION RESEARCH

EPA Science Inventory

Metal contaminated environmental systems (soils, sediments, and water) have challenged researchers for many years. Traditional methods of analysis have employed extraction methods to determine total metal content and define risk based on the premise that as metal concentration in...

Relationship between the lability of sediment-bound Cd and its bioaccumulation in edible oyster.

PubMed

Chakraborty, Parthasarathi; Ramteke, Darwin; Chakraborty, Sucharita; Chennuri, Kartheek; Bardhan, Pratirupa

2015-11-15

A linkage between Cd speciation in sediments and its bioaccumulation in edible oyster (Crassostrea sp.) from a tropical estuarine system was established. Bioaccumulation of Cd in edible oyster increased with the increasing lability and dissociation rate constants of Cd-sediment complexes in the bottom sediments. Total Cd concentration in sediment was not a good indicator of Cd-bioavailability. Increasing trace metal competition in sediments increased lability and bioavailability of Cd in the tropical estuarine sediment. Low thermodynamic stability and high bioavailability of Cd in the estuarine sediment were responsible for high bioaccumulation of Cd in edible oysters (3.2-12.2mgkg(-1)) even though the total concentration of Cd in the bottom sediment was low (0.17-0.49mgkg(-1)). Copyright © 2015 Elsevier Ltd. All rights reserved.

Chemical imaging analysis of the brain with X-ray methods

NASA Astrophysics Data System (ADS)

Collingwood, Joanna F.; Adams, Freddy

2017-04-01

Cells employ various metal and metalloid ions to augment the structure and the function of proteins and to assist with vital biological processes. In the brain they mediate biochemical processes, and disrupted metabolism of metals may be a contributing factor in neurodegenerative disorders. In this tutorial review we will discuss the particular role of X-ray methods for elemental imaging analysis of accumulated metal species and metal-containing compounds in biological materials, in the context of post-mortem brain tissue. X-rays have the advantage that they have a short wavelength and can penetrate through a thick biological sample. Many of the X-ray microscopy techniques that provide the greatest sensitivity and specificity for trace metal concentrations in biological materials are emerging at synchrotron X-ray facilities. Here, the extremely high flux available across a wide range of soft and hard X-rays, combined with state-of-the-art focusing techniques and ultra-sensitive detectors, makes it viable to undertake direct imaging of a number of elements in brain tissue. The different methods for synchrotron imaging of metals in brain tissues at regional, cellular, and sub-cellular spatial resolution are discussed. Methods covered include X-ray fluorescence for elemental imaging, X-ray absorption spectrometry for speciation imaging, X-ray diffraction for structural imaging, phase contrast for enhanced contrast imaging and scanning transmission X-ray microscopy for spectromicroscopy. Two- and three-dimensional (confocal and tomographic) imaging methods are considered as well as the correlation of X-ray microscopy with other imaging tools.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Valin, R.; Morse, J.W.

The operation of an OTEC plant will result in the mixing of large volumes of seawater from different depths within the ocean. Because suspended particulate material is intimately involved in marine food webs and transition metals, such as copper, can have toxic effects, it is important to develop a sound methodology for characterizing and quantifying transition metal behavior associated with the solid material. The characterization of solid-phase-associated transition metals in the marine environment has largely been directed at marine sediments. These studies have generally indicated that it is not possible to uniquely identify the solid phases or chemical speciation ofmore » a given metal. There are many reasons for this difficulty, but the probable major analytical problems arise from the fact that many of the transition metals of interest are present only in trace concentrations as adsorbed species on amorphous oxides or as coprecipitates. In one approach transition metals are classified according to how easily they are solubilized when exposed to different types of chemical attack, as defined in chemical extraction schemes. In this study, several of the most widely accepted extraction techniques were compared for many of the most commonly measured transition metals to a variety of marine sediments. Based on the results of this study, the sequential extraction scheme of Tessler et al. (1979) is the recommended method for the characterization of solid-phase associated transition metals. An increase of the reducing agent concentration in the intermediate step and temperature decrease with an additional HCl digestion in the residual step are recommended as improvements, based on the results of the individual extraction method studies.« less

Speciation and transformation of heavy metals during vermicomposting of animal manure.

PubMed

Lv, Baoyi; Xing, Meiyan; Yang, Jian

2016-06-01

This work was conducted to evaluate the effects of vermicomposting on the speciation and mobility of heavy metals (Zn, Pb, Cr, and Cu) in cattle dung (CD) and pig manure (PM) using tessier sequential extraction method. Results showed that the pH, total organic carbon and C/N ratio were reduced, while the electric conductivity and humic acid increased after 90days vermicomposting. Moreover, the addition of earthworm could accelerate organic stabilization in vermicomposting. The total heavy metals in final vermicompost from CD and PM were higher than the initial values and the control without worms. Sequential extraction indicated that vermicomposting decreased the migration and availability of heavy metals, and the earthworm could reduce the mobile fraction, while increase the stable fraction of heavy metals. Furthermore, these results indicated that vermicomposting played a positive role in stabilizing heavy metals in the treatment of animal manure. Copyright © 2016 Elsevier Ltd. All rights reserved.

Speciation Mapping of Environmental Samples Using XANES Imaging

EPA Science Inventory

Fast X-ray detectors with large solid angles and high dynamic ranges open the door to XANES imaging, in which millions of spectra are collected to image the speciation of metals at micrometre resolution, over areas up to several square centimetres. This paper explores how such mu...

Organotin speciation in environmental matrices by automated on-line hydride generation-programmed temperature vaporization-capillary gas chromatography-mass spectrometry detection.

PubMed

Serra, H; Nogueira, J M F

2005-11-11

In the present contribution, a new automated on-line hydride generation methodology was developed for dibutyltin and tributyltin speciation at the trace level, using a programmable temperature-vaporizing inlet followed by capillary gas chromatography coupled to mass spectrometry in the selected ion-monitoring mode acquisition (PTV-GC/MS(SIM)). The methodology involves a sequence defined by two running methods, the first one configured for hydride generation with sodium tetrahydroborate as derivatising agent and the second configured for speciation purposes, using a conventional autosampler and data acquisition controlled by the instrument's software. From the method-development experiments, it had been established that injector configuration has a great effect on the speciation of the actual methodology, particularly, the initial inlet temperature (-20 degrees C; He: 150 ml/min), injection volume (2 microl) and solvent characteristics using the solvent venting mode. Under optimized conditions, a remarkable instrumental performance including very good precision (RSD < 4%), excellent linear dynamic range (up to 50 microg/ml) and limits of detection of 0.12 microg/ml and 9 ng/ml, were obtained for dibutyltin and tributyltin, respectively. The feasibility of the present methodology was validated through assays upon in-house spiked water (2 ng/ml) and a certified reference sediment matrix (Community Bureau of Reference, CRM 462, Nr. 330 dibutyltin: 68+/-12 ng/g; tributyltin: 54+/-15 ng/g on dry mass basis), using liquid-liquid extraction (LLE) and solid-phase extraction (SPE) sample enrichment and multiple injections (2 x 5 microl) for sensitivity enhancement. The methodology evidenced high reproducibility, is easy to work-up, sensitive and showed to be a suitable alternative to replace the currently dedicated analytical systems for organotin speciation in environmental matrices at the trace level.

Soil-solution speciation of Cd as affected by soil characteristics in unpolluted and polluted soils.

PubMed

Meers, Erik; Unamuno, Virginia; Vandegehuchte, Michiel; Vanbroekhoven, Karolien; Geebelen, Wouter; Samson, Roeland; Vangronsveld, Jaco; Diels, Ludo; Ruttens, Ann; Du Laing, Gijs; Tack, Filip

2005-03-01

Total metal content by itself is insufficient as a measure to indicate actual environmental risk. Understanding the mobility of heavy metals in the soil and their speciation in the soil solution is of great importance for accurately assessing environmental risks posed by these metals. In a first explorative study, the effects of general soil characteristics on Cd mobility were evaluated and expressed in the form of empirical formulations. The most important factors influencing mobility of Cd proved to be pH and total soil content. This may indicate that current legislation expressing the requirement for soil sanitation in Flanders (Belgium) as a function of total soil content, organic matter, and clay does not successfully reflect actual risks. Current legal frameworks focusing on total content, therefore, should be amended with criteria that are indicative of metal mobility and availability and are based on physicochemical soil properties. In addition, soil-solution speciation was performed using two independent software packages (Visual Minteq 2.23 and Windermere Humic Aqueous model VI [WHAM VI]). Both programs largely were in agreement in concern to Cd speciation in all 29 soils under study. Depending on soil type, free ion and the organically complexed forms were the most abundant species. Additional inorganic soluble species were sulfates and chlorides. Minor species in solution were in the form of nitrates, hydroxides, and carbonates, the relative importance of which was deemed insignificant in comparison to the four major species.

Organochlorines in surface soil at electronic-waste wire burning sites and metal contribution evaluated using quantitative X-ray speciation

NASA Astrophysics Data System (ADS)

Fujimori, Takashi; Takigami, Hidetaka; Takaoka, Masaki

2013-04-01

Heavy metals and toxic chlorinated aromatic compounds (aromatic-Cls) such as dioxins and polychlorinated biphenyls (PCBs) are found at high concentrations and persist in surface soil at wire burning sites (WBSs) in developing countries in which various wire cables are recycled to yield pure metals. Chlorine K-edge near-edge X-ray absorption fine structure (NEXAFS) is used to detect the specific chemical form of Cl and estimate its amount using a spectrum jump in the solid phase. Quantitative X-ray speciation of Cl was applied to study the mechanisms of aromatic-Cls formation in surface soil at WBSs in Southeast Asia. Relationships between aromatic-Cls and chlorides of heavy metals were evaluated because heavy metals are promoters of the thermochemical solid-phase formation of aromatic-Cls.

Chemical Speciation and Metallomics.

PubMed

de Jesus, Jemmyson Romário; da Costa, Luana Ferreira; Lehmann, Eraldo Luiz; Galazzi, Rodrigo Moretto; Madrid, Katherine Chacón; Arruda, Marco Aurélio Zezzi

2018-01-01

Chemical speciation approaches is an inherent part of metallomics, once metals/metalloids and organic structures need to be currently evaluated for attaining metallomics studies. Then, this chapter focuses on the applications of the chemical speciation applied to the human health risk, food and human diet, drugs, forensic, nanoscience, and geological metallomics, also pointing out the advances in such area. Some aspects regarding sample preparation is commented along this chapter, and some strategies for maintaining the integrity of the metallomics information are also emphasized.

The phosphorus speciations in the sediments up- and down-stream of cascade dams along the middle Lancang River.

PubMed

Liu, Qi; Liu, Shiliang; Zhao, Haidi; Deng, Li; Wang, Cong; Zhao, Qinghe; Dong, Shikui

2015-02-01

We detected the longitudinal variability of phosphorus speciations and its relation to metals and grain size distribution of sediments in three cascade canyon reservoirs (Xiaowan, Manwan and Dachaoshan) along Lancang River, China. Five phosphorus speciations including loosely bound P (ex-P), reductant soluble P (BD-P), metal oxide-bound P (NaOH-P) calcium-bound P (HCl-P) and residual-P were extracted and quantified. Results showed that in Manwan Reservoir HCl-P accounted for the largest part of total phosphorus (TP) (49.69%), while in Xiaowan and Dachaoshan reservoirs, NaOH-P was the most abundant speciation which accounted for 57.21% and 55.19% of total phosphorus respectively. Higher contents of bio-available phosphorus in Xiaowan and Dachaoshan reservoirs suggested a high rate of P releasing from sediments. Results also showed ex-P and HCl-P had positive correlation with Ca. Total phosphorus was positively correlated with Fe. The silt/clay contents of the sediments had close relationship with ex-P (r=0.413, p<0.05), NaOH-P (r=0.428, p<0.05) and BAP (r=0.458, p<0.05). The concentration of Ca, Mn and silt/clay speciation in the sediments explained 40%, 10% and 4% of the spatial variation of phosphorus speciations, respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

Pleistocene phylogeographic effects on avian populations and the speciation process.

PubMed Central

Avise, J C; Walker, D

1998-01-01

Pleistocene biogeographic events have traditionally been ascribed a major role in promoting speciations and in sculpting the present-day diversity and distributions of vertebrate taxa. However, this paradigm has recently come under challenge from a review of interspecific mtDNA genetic distances in birds: most sister-species separations dated to the Pliocene. Here we summarize the literature on intraspecific mtDNA phylogeographic patterns in birds and reinterpret the molecular evidence bearing on Pleistocene influences. At least 37 of the 63 avian species surveyed (59%) are sundered into recognizable phylogeographic units, and 28 of these separations (76%) trace to the Pleistocene. Furthermore, use of phylogroup separation times within species as minimum estimates of 'speciation durations' also indicates that many protracted speciations, considered individually, probably extended through time from Pliocene origins to Pleistocene completions. When avian speciation is viewed properly as an extended temporal process rather than as a point event, Pleistocene conditions appear to have played an active role both in initiating major phylogeographic separations within species, and in completing speciations that had been inaugurated earlier. Whether the Pleistocene was exceptional in these regards compared with other geological times remains to be determined. PMID:9569664

Sources, spatial variation, and speciation of heavy metals in sediments of the Tamagawa River in Central Japan.

PubMed

Shikazono, N; Tatewaki, K; Mohiuddin, K M; Nakano, T; Zakir, H M

2012-01-01

Sediments of the Tamagawa River in central Japan were studied to explain the spatial variation, to identify the sources of heavy metals, and to evaluate the anthropogenic influence on these pollutants in the river. Sediment samples were collected from 20 sites along the river (five upstream, four midstream, and 11 downstream). Heavy metal concentrations, viz. chromium, nickel, copper, zinc, lead, cadmium, and molybdenum, in the samples were measured using inductively coupled plasma-mass spectroscopy. The chemical speciations of heavy metals in the sediments were identified by the widely used five-step Hall method. Lead isotopes were analyzed to identify what portion is contributed by anthropogenic sources. The total heavy metal concentrations were compared with global averages for continental crust (shale) and average values for Japanese river sediments. The mean heavy metal concentrations were higher in downstream sediments than in upstream and midstream samples, and the concentrations in the silt samples were higher than those in the sand samples. Speciation results demonstrate that, for chromium and nickel, the residual fractions were dominant. These findings imply that the influence of anthropogenic chromium and nickel contamination is negligible, while copper, zinc, and lead were mostly extracted in the non-residual fraction (metals in adsorbed/exchangeable/carbonate forms or bound to amorphous Fe oxyhydroxides, crystalline Fe oxides, or organic matter), indicating that these elements have high chemical mobility. The proportion of lead (Pb) isotopes in the downstream silt samples indicates that Pb accumulation is primarily derived from anthropogenic sources.

Tracing the recombination and colonization history of hybrid species in space and time.

PubMed

Lexer, C; Stölting, K N

2011-09-01

Hybrid speciation has long fascinated evolutionary biologists and laymen alike, presumably because it challenges our classical view of evolution as a 'one-way street' leading to strictly tree-like patterns of ancestry and descent. Homoploid hybrid speciation (HHS) has been a particularly interesting puzzle, as it appears to occur extremely rapidly, perhaps within less than 50 generations (McCarthy et al. 1995; Buerkle et al. 2000). Nevertheless, HHS may sometimes involve extended or repeated periods of recombination and gene exchange between populations subject to strong divergent natural selection (Buerkle & Rieseberg 2008). Thus, HHS provides a highly interesting setting for understanding the drivers and tempo of adaptive divergence and speciation in the face of gene flow (Arnold 2006; Rieseberg & Willis 2007; Nolte & Tautz 2009). In the present issue of Molecular Ecology, Wang et al. (2011) explore a particularly challenging issue connected to HHS: they attempt to trace the colonization and recombination history of an ancient (several MYA) hybrid species, from admixture and recombination in the ancestral hybrid zone to subsequent range shifts triggered by tectonic events (uplift of the Tibetan plateau) and climatic shifts (Pleistocene ice ages). This work is important because it addresses key issues related to the origin of the standing genetic variation available for adaptive responses (e.g. to climate change) and speciation in temperate species, which are topics of great current interest (Rieseberg et al. 2003; Barrett & Schluter 2008; de Carvalho et al. 2010). © 2011 Blackwell Publishing Ltd.

Speciation of the trivalent f-elements Eu(III) and Cm(III) in digestive media.

PubMed

Wilke, Claudia; Barkleit, Astrid; Stumpf, Thorsten; Ikeda-Ohno, Atsushi

2017-10-01

In case radioactive materials are released into the environment, their incorporation into our digestive system would be a significant concern. Trivalent f-elements, i.e., trivalent actinides and lanthanides, could potentially represent a serious health risk due to their chemo- and radiotoxicity, nevertheless the biochemical behavior of these elements are mostly unknown even to date. This study, therefore, focuses on the chemical speciation of trivalent f-elements in the human gastrointestinal tract. To simulate the digestive system artificial digestive juices (saliva, gastric juice, pancreatic juice and bile fluid) were prepared. The chemical speciation of lanthanides (as Eu(III)) and actinides (as Cm(III)) was determined experimentally by time-resolved laser-induced fluorescence spectroscopy (TRLFS) and the results were compared with thermodynamic modeling. The results indicate a dominant inorganic species with phosphate/carbonate in the mouth, while the aquo ion is predominantly formed with a minor contribution of the enzyme pepsin in the stomach. In the intestinal tract the most significant species are with the protein mucin. We demonstrated the first experimental results on the chemical speciation of trivalent f-elements in the digestive media by TRLFS. The results highlight a significant gap in chemical speciation between experiments and thermodynamic modeling due to the limited availability of thermodynamic stability constants particularly for organic species. Chemical speciation strongly influences the in vivo behavior of metal ions. Therefore, the results of this speciation study will help to enhance the assessment of health risks and to improve decorporation strategies after ingestion of these (radio-)toxic heavy metal ions. Copyright © 2017 Elsevier Inc. All rights reserved.

Mercury behaviour and C, N, and P biogeochemical cycles during ecological restoration processes of old mining sites in French Guiana.

PubMed

Couic, Ewan; Grimaldi, Michel; Alphonse, Vanessa; Balland-Bolou-Bi, Clarisse; Livet, Alexandre; Giusti-Miller, Stéphanie; Sarrazin, Max; Bousserrhine, Noureddine

2018-04-25

Several decades of gold mining extraction activities in the Amazonian rainforest have caused deforestation and pollution. While ecological rehabilitation is essential for restoring biodiversity and decreasing erosion on deforested lands, few studies note the behaviour or toxicity of trace elements during the rehabilitation process. Our original study focused on the potential use of microbial activity and Hg speciation and compared them with As, Cu, Zn and Cr speciation in assessing the chemical and biological quality of ecological restoration efforts. We sampled two sites in French Guyana 17 years after rehabilitation efforts began. The former site was actively regenerated (R) with the leguminous species Clitoria racemosa and Acacia mangium, and the second site was passively regenerated with spontaneous vegetation (Sv). We also sampled soil from a control site without a history of gold mining (F). We performed microcosm soil experiments for 30 days, where trace element speciation and enzyme activities (i.e., FDA, dehydrogenase, β-glucosidase, urease, alkaline and acid phosphatase) were estimated to characterise the behaviour of trace elements and the soil microbial activity. As bioindicators, the use of soil microbial carbon biomass and soil enzyme activities related to the carbon and phosphorus cycles seems to be relevant for assessing soil quality in rehabilitated and regenerated old mining sites. Our results showed that restoration with leguminous species had a positive effect on soil chemical quality and on soil microbial bioindicators, with activities that tended toward natural non-degraded soil (F). Active restoration processes also had a positive effect on Hg speciation by reducing its mobility. While in Sv we found more exchangeable and soluble mercury, in regenerated sites, Hg was mostly bound to organic matter. These results also suggested that enzyme activities and mercury cycles are sensitive to land restoration and must be considered when evaluating the efficiency of restoration processes.

Arsenic speciation and trace element analysis of the volcanic río Agrio and the geothermal waters of Copahue, Argentina.

PubMed

Farnfield, Hannah R; Marcilla, Andrea L; Ward, Neil I

2012-09-01

Surface water originating from the Copahue volcano crater-lake was analysed for total arsenic and four arsenic species: arsenite (iAs(III)), arsenate (iAs(V)), monomethylarsonic acid (MA(V)) and dimethylarsinic acid (DMA(V)) and other trace elements (Fe, Mn, V, Cr, Ni, Zn). A novel in-field technique for the preconcentration and separation of four arsenic species was, for the first time, used for the analysis of geothermal and volcanic waters. Total arsenic levels along the río Agrio ranged from <0.2-3783 μg/l As(T). The highest arsenic levels were recorded in the el Vertedero spring (3783 μg/l As(T)) on the flank of the Copahue volcano, which feeds the acidic río Agrio. Arsenite (H(3)AsO(3)) predominated along the upper río Agrio (78.9-81.2% iAs(III)) but the species distribution changed at lago Caviahue and arsenate (H(2)AsO(4)(-)) became the main species (51.4-61.4% iAs(V)) up until Salto del Agrio. The change in arsenic species is potentially a result of an increase in redox potential and the formation of iron-based precipitates. Arsenic speciation showed a statistically significant correlation with redox potential (r=0.9697, P=0.01). Both total arsenic and arsenic speciation displayed a statistically significant correlation with vanadium levels along the river (r=0.9961, P=0.01 and r=0.8488, P=0.05, respectively). This study highlights that chemical speciation analysis of volcanic waters is important in providing ideas on potential chemical toxicity. Furthermore there is a need for further work evaluating how arsenic (and other trace elements), released in volcanic and geothermal streams/vents, impacts on both biota and humans (via exposure in thermal pools or consuming commercial drinking water). Copyright © 2012 Elsevier B.V. All rights reserved.

Effects of conversion of mangroves into gei wai ponds on accumulation, speciation and risk of heavy metals in intertidal sediments.

PubMed

Li, Rongyu; Qiu, Guo Yu; Chai, Minwei; Shen, Xiaoxue; Zan, Qijie

2018-06-23

Mangroves are often converted into gei wai ponds for aquaculture, but how such conversion affects the accumulation and behavior of heavy metals in sediments is not clear. The present study aims to quantify the concentration and speciation of heavy metals in sediments in different habitats, including gei wai pond, mangrove marsh dominated by Avicennia marina and bare mudflat, in a mangrove nature reserve in South China. The results showed that gei wai pond acidified the sediment and reduced its electronic conductivity and total organic carbon (TOC) when compared to A. marina marsh and mudflat. The concentrations of Cd, Cu, Zn and Pb at all sediment depths in gei wai pond were lower than the other habitats, indicating gei wai pond reduced the fertility and the ability to retain heavy metals in sediment. Gei wai pond sediment also had a lower heavy metal pollution problem according to multiple evaluation methods, including potential ecological risk coefficient, potential ecological risk index, geo-accumulation index, mean PEL quotients, pollution load index, mean ERM quotients and total toxic unit. Heavy metal speciation analysis showed that gei wai pond increased the transfer of the immobilized fraction of Cd and Cr to the mobilized one. According to the acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) analysis, the conversion of mangroves into gei wai pond reduced values of ([SEM] - [AVS])/f oc , and the role of TOC in alleviating heavy metal toxicity in sediment. This study demonstrated the conversion of mangrove marsh into gei wai pond not only reduced the ecological purification capacity on heavy metal contamination, but also enhanced the transfer of heavy metals from gei wai pond sediment to nearby habitats.

Long-term leaching from recycled concrete aggregates applied as sub-base material in road construction.

PubMed

Engelsen, Christian J; van der Sloot, Hans A; Petkovic, Gordana

2017-06-01

In the present study, the metal leaching from recycled concrete aggregates (RCA) used in road sub-base is presented after >10years of exposure. The released levels of inorganic constituents, the effect of small variation of pH and the use of de-icing salt during winter season were studied. In addition, speciation modelling for the major elements has been provided. The pH varied from 7.5 to 8.5 for the sub-base constructed with RCA whereas the pH of around 8 was obtained for the test section not affected by the traffic and de-icing salts. Despite a small variation in pH, the leachability of Al, Ca and Mg was found to be strongly dependent on pH and fair agreement between the measured and predicted concentrations was obtained. The speciation modelling indicated that gibbsite, calcite and magnesite controlled the solubility of Al, Ca and Mg, respectively, which was in agreement with the expected carbonation products. Due to the larger pH fluctuations in the test sections exposed to the road traffic, increased concentrations were observed for the oxyanions. The same effect was not seen for the trace metal cations Cd, Cu, Ni, Pb and Zn. The distinct pH dependent leaching profile (solubility maximum in the mildly basic pH region) for vanadium could be seen after 10years of exposure. The simplified risk assessment showed that the released quantities did not exceed the chosen acceptance criteria for groundwater and fresh water. The results obtained for the test section not influenced by road dust and de-icing salts, complied with these criteria even without considering any dilution effects caused by the mixing of pore water with groundwater. Copyright © 2017 Elsevier B.V. All rights reserved.

Source tracing of fluvial suspended sediments by magnetic and geochemical particle characterization: example of the Canche watershed (Nord-Pas-de-Calais, France)

NASA Astrophysics Data System (ADS)

Patault, Edouard; Alary, Claire; Franke, Christine; Gauthier, Arnaud; Abriak, Nor-Edine

2016-04-01

In France, erosion by water run-off is estimated to 1.5 t ha-1yr-1 and can exceed 10 t ha-1yr-1 in large growing areas, such as the North of France (Nord-Pas-de-Calais). In this region, the Canche watershed (1294 km2) sustains heavy loss of fertile soils. The land use is mainly dominated by arable lands (80%) and in 2013, 104 kt of suspended sediment transited to the estuary. As demonstrated in literature, agricultural soil erosion leads to the gradual disappearance and depletion of fertile soil, which constitute a non-renewable resource at human time scale. Additionally, water erosion can significantly damage the aquatic habitat and can be responsible for the input of nutrients, bacteria, pesticides, heavy metals and radionuclides into surface waters. Conscious of these effects, many programs have emerged in the Nord-Pas-de-Calais to reduce erosion. This study presents a combination of environmental magnetic proxy parameters and geochemical analyses on sediments and suspended particulate matter. The aim is to develop effective tools to trace erosion by water run-off and quantify this process. In order to identify the respective sediment sources in the Canche watershed, sediment trap samples of suspended particulate matter were recovered at key positions along the Canche watershed. The preliminary results show that magnetic concentration (Mrs) shows typical values for the agricultural soils in the region, but these variations in magnetic concentrations and total irons concentrations are not always correlated, which may be explained by the iron speciation. In calculating the so-called S-ratio for each sample we can distinguish changes in magneto-mineralogy (and thus iron speciation) from magnetite-dominated assemblages in the mainstream Canche (naturel background signal) to high-coercivity-dominated assemblages in the tributaries, typical for soil erosion material rich in hematite/goethite. In combination with the element concentrations from ICP analyses, this proxy parameter may give valuable insight into the tracing of the suspended sediment sources. In perspective, the seasonal variability and the discharge in the Canche watershed have to be taken into account.

Biogeochemical redox processes and their impact on contaminant dynamics

USGS Publications Warehouse

Borch, Thomas; Kretzschmar, Ruben; Kappler, Andreas; Van Cappellen, Philippe; Ginder-Vogel, Matthew; Campbell, Kate M.

2010-01-01

Life and element cycling on Earth is directly related to electron transfer (or redox) reactions. An understanding of biogeochemical redox processes is crucial for predicting and protecting environmental health and can provide new opportunities for engineered remediation strategies. Energy can be released and stored by means of redox reactions via the oxidation of labile organic carbon or inorganic compounds (electron donors) by microorganisms coupled to the reduction of electron acceptors including humic substances, iron-bearing minerals, transition metals, metalloids, and actinides. Environmental redox processes play key roles in the formation and dissolution of mineral phases. Redox cycling of naturally occurring trace elements and their host minerals often controls the release or sequestration of inorganic contaminants. Redox processes control the chemical speciation, bioavailability, toxicity, and mobility of many major and trace elements including Fe, Mn, C, P, N, S, Cr, Cu, Co, As, Sb, Se, Hg, Tc, and U. Redox-active humic substances and mineral surfaces can catalyze the redox transformation and degradation of organic contaminants. In this review article, we highlight recent advances in our understanding of biogeochemical redox processes and their impact on contaminant fate and transport, including future research needs.

The flotation tailings of the former Pb-Zn mine of Touiref (NW Tunisia): mineralogy, mine drainage prediction, base-metal speciation assessment and geochemical modeling.

PubMed

Othmani, Mohamed Ali; Souissi, Fouad; Bouzahzah, Hassan; Bussière, Bruno; da Silva, Eduardo Ferreira; Benzaazoua, Mostafa

2015-02-01

The underground extraction of Pb-Zn mineralization in the Touiref area stopped in 1958. A large volume of flotation tailings (more than 500 Mt) containing sulfides were deposited in a tailings impoundment. The goals of this study are to evaluate the neutralization capacity of the unoxidized and oxidized tailings, to assess the speciation of metals between the different components of the tailings material, and to assess the mobility of metals and the secondary minerals' precipitation in pore waters using geochemical modeling. To accomplish these objectives, representative samples from both fresh and oxidized zones were collected along a vertical profile through the tailings pile. Physical, chemical (ICP-MS), and mineralogical characterization (X-ray diffraction (XRD), reflected light microscopy, scanning electron microscope (SEM)) of these samples was performed. Grain size analysis shows that the tailings are dominated by silt- to sand-sized fractions. The microscopic observation highlights the presence of pyrite, marcasite, galena, and sphalerite as primary minerals in a carbonated matrix. The study reveals also the presence of secondary minerals represented by cerussite, smithsonite, anglesite, and Fe oxi-hydroxides as important scavengers for trace elements. The static tests show that the presence of calcite in the tailing samples ensures acid-neutralizing capacity (ANC), which is significantly greater than the acidity potential (PA). The geochemical characterization of the unoxidized samples shows higher Cd, Pb, and Zn concentrations than the oxidized samples containing the highest values for Fe and SO4. Sequential extraction tests show that significant percentages of metals are distributed between the acid-soluble fractions (Cd, Pb, and Zn) and the reducible one (Zn). Pore water analysis indicates that Ca is the dominant cation (8,170 and 6,200 mg L(-1), respectively), whereas sulfate is the principal anion (6,900 and 5,100 mg L(-1), respectively). Saturation index (SI) calculations of minerals in pore water extracted from both the oxidized and unoxidized samples are indicative of gypsum (SI >0) and Fe(III) oxides (SI ≫0) precipitation. The latter controls the Fe concentration in solution.

Chromium speciation, bioavailability, uptake, toxicity and detoxification in soil-plant system: A review.

PubMed

Shahid, Muhammad; Shamshad, Saliha; Rafiq, Marina; Khalid, Sana; Bibi, Irshad; Niazi, Nabeel Khan; Dumat, Camille; Rashid, Muhammad Imtiaz

2017-07-01

Chromium (Cr) is a potentially toxic heavy metal which does not have any essential metabolic function in plants. Various past and recent studies highlight the biogeochemistry of Cr in the soil-plant system. This review traces a plausible link among Cr speciation, bioavailability, phytouptake, phytotoxicity and detoxification based on available data, especially published from 2010 to 2016. Chromium occurs in different chemical forms (primarily as chromite (Cr(III)) and chromate (Cr(VI)) in soil which vary markedly in term of their biogeochemical behavior. Chromium behavior in soil, its soil-plant transfer and accumulation in different plant parts vary with its chemical form, plant type and soil physico-chemical properties. Soil microbial community plays a key role in governing Cr speciation and behavior in soil. Chromium does not have any specific transporter for its uptake by plants and it primarily enters the plants through specific and non-specific channels of essential ions. Chromium accumulates predominantly in plant root tissues with very limited translocation to shoots. Inside plants, Cr provokes numerous deleterious effects to several physiological, morphological, and biochemical processes. Chromium induces phytotoxicity by interfering plant growth, nutrient uptake and photosynthesis, inducing enhanced generation of reactive oxygen species, causing lipid peroxidation and altering the antioxidant activities. Plants tolerate Cr toxicity via various defense mechanisms such as complexation by organic ligands, compartmentation into the vacuole, and scavenging ROS via antioxidative enzymes. Consumption of Cr-contaminated-food can cause human health risks by inducing severe clinical conditions. Therefore, there is a dire need to monitor biogeochemical behavior of Cr in soil-plant system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mobility and fluxes of major, minor and trace metals during basalt weathering and groundwater transport at Mt. Etna volcano (Sicily)

NASA Astrophysics Data System (ADS)

Aiuppa, Alessandro; Allard, Patrick; D'Alessandro, Walter; Michel, Agnes; Parello, Francesco; Treuil, Michel; Valenza, Mariano

2000-06-01

The concentrations and fluxes of major, minor and trace metals were determined in 53 samples of groundwaters from around Mt Etna, in order to evaluate the conditions and extent of alkali basalt weathering by waters enriched in magma-derived CO 2 and the contribution of aqueous transport to the overall metal discharge of the volcano. We show that gaseous input of magmatic volatile metals into the Etnean aquifer is small or negligible, being limited by cooling of the rising fluids. Basalt leaching by weakly acidic, CO 2-charged water is the overwhelming source of metals and appears to be more extensive in two sectors of the S-SW (Paternò) and E (Zafferana) volcano flanks, where out flowing groundwaters are the richest in metals and bicarbonate of magmatic origin. Thermodynamic modeling of the results allows to evaluate the relative mobility and chemical speciation of various elements during their partitioning between solid and liquid phases through the weathering process. The facts that rock-forming minerals and groundmass dissolve at different rates and secondary minerals are formed are taken into account. At Mt. Etna, poorly mobile elements (Al, Th, Fe) are preferentially retained in the solid residue of weathering, while alkalis, alkaline earth and oxo-anion-forming elements (As, Se, Sb, Mo) are more mobile and released to the aqueous system. Transition metals display an intermediate behavior and are strongly dependent on either the redox conditions (Mn, Cr, V) or solid surface-related processes (V, Zn, Cu). The fluxes of metals discharged by the volcanic aquifer of Etna range from 7.0 × 10 -3 t/a (Th) to 7.3 × 10 4 t/a (Na). They are comparable in magnitude to the summit crater plume emissions for a series of elements (Na, K, Ca, Mg, U, V, Li) with lithophile affinity, but are minor for volatile elements. Basalt weathering at Mt Etna also consumes about 2.1 × 10 5 t/a of magma-derived carbon dioxide, equivalent to ca. 7% of contemporaneous crater plume emissions. The considerable transport of some metals in Etna's aquifer reflects a particularly high chemical erosion rate, evaluated at 2.3∗10 5 t/a, enhanced by the initial acidity of magmatic CO 2-rich groundwater.

Humic substances-part 7: the biogeochemistry of dissolved organic carbon and its interactions with climate change.

PubMed

Porcal, Petr; Koprivnjak, Jean-François; Molot, Lewis A; Dillon, Peter J

2009-09-01

Dissolved organic matter, measured as dissolved organic carbon (DOC), is an important component of aquatic ecosystems and of the global carbon cycle. It is known that changes in DOC quality and quantity are likely to have ecological repercussions. This review has four goals: (1) to discuss potential mechanisms responsible for recent changes in aquatic DOC concentrations; (2) to provide a comprehensive overview of the interactions between DOC, nutrients, and trace metals in mainly boreal environments; (3) to explore the impact of climate change on DOC and the subsequent effects on nutrients and trace metals; and (4) to explore the potential impact of DOC cycling on climate change. We review recent research on the mechanisms responsible for recent changes in aquatic DOC concentrations, DOC interactions with trace metals, N, and P, and on the possible impacts of climate change on DOC in mainly boreal lakes. We then speculate on how climate change may affect DOC export and in-lake processing and how these changes might alter nutrient and metal export and processing. Furthermore, the potential impacts of changing DOC cycling patterns on climate change are examined. It has been noted that DOC concentrations in lake and stream waters have increased during the last 30 years across much of Europe and North America. The potential reasons for this increase include increasing atmospheric CO(2) concentration, climate warming, continued N deposition, decreased sulfate deposition, and hydrological changes due to increased precipitation, droughts, and land use changes. Any change in DOC concentrations and properties in lakes and streams will also impact the acid-base chemistry of these waters and, presumably, the biological, chemical, and photochemical reactions taking place. For example, the interaction of trace metals with DOC may be significantly altered by climate change as organically complexed metals such as Cu, Fe, and Al are released during photo-oxidation of DOC. The production and loss of DOC as CO(2) from boreal lakes may also be affected by changing climate. Climate change is unlikely to be uniform spatially with some regions becoming wetter while others become drier. As a result, rates of change in DOC export and concentrations will vary regionally and the changes may be non-linear. Climate change models predict that higher temperatures are likely to occur over most of the boreal forests in North America, Europe, and Asia over the next century. Climate change is also expected to affect the severity and frequency of storm and drought events. Two general climate scenarios emerge with which to examine possible DOC trends: warmer and wetter or warmer and drier. Increasing temperature and hydrological changes (specifically, runoff) are likely to lead to changes in the quality and quantity of DOC export from terrestrial sources to rivers and lakes as well as changes in DOC processing rates in lakes. This will alter the quality and concentrations of DOC and its constituents as well as its interactions with trace metals and the availability of nutrients. In addition, export rates of nutrients and metals will also change in response to changing runoff. Processing of DOC within lakes may impact climate depending on the extent to which DOC is mineralized to dissolved inorganic carbon (DIC) and evaded to the atmosphere or settles as particulate organic carbon (POC) to bottom sediments and thereby remaining in the lake. The partitioning of DOC between sediments and the atmosphere is a function of pH. Decreased DOC concentrations may also limit the burial of sulfate, as FeS, in lake sediments, thereby contributing acidity to the water by increasing the formation of H(2)S. Under a warmer and drier scenario, if lake water levels fall, previously stored organic sediments may be exposed to greater aeration which would lead to greater CO(2) evasion to the atmosphere. The interaction of trace metals with DOC may be significantly altered by climate change. Iron enhances the formation of POC during irradiation of lake water with UV light and therefore may be an important pathway for transfer of allochthonous DOC to the sediments. Therefore, changing Fe/DOC ratios could affect POC formation rates. If climate change results in altered DOC chemistry (e.g., fewer and/or weaker binding sites) more trace metals could be present in their toxic and bioavailable forms. The availability of nutrients may be significantly altered by climate change. Decreased DOC concentrations in lakes may result in increased Fe colloid formation and co-incident loss of adsorbable P from the water column. Climate change expressed as changes in runoff and temperature will likely result in changes in aquatic DOC quality and concentration with concomitant effects on trace metals and nutrients. Changes in the quality and concentration of DOC have implications for acid-base chemistry and for the speciation and bioavailability of certain trace metals and nutrients. Moreover, changes in DOC, metals, and nutrients are likely to drive changes in rates of C evasion and storage in lake sediments. The key controls on allochthonous DOC quality, quantity, and catchment export in response to climate change are still not fully understood. More detailed knowledge of these processes is required so that changes in DOC and its interactions with nutrients and trace metals can be better predicted based on changes caused by changing climate. More studies are needed concerning the effects of trace metals on DOC, the effects of changing DOC quality and quantity on trace metals and nutrients, and how runoff and temperature-related changes in DOC export affect metal and nutrient export to rivers and lakes.

Heavy metal speciation, leaching and toxicity status of a tropical rain-fed river Damodar, India.

PubMed

Pal, Divya; Maiti, Subodh Kumar

2018-03-26

Speciations of metals were assessed in a tropical rain-fed river, flowing through the highly economically important part of the India. The pattern of distribution of heavy metals (Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn) were evaluated in water and sediment along with mineralogical characterization, changes with different water quality parameters and their respective health hazard to the local population along the Damodar River basin during pre-monsoon and post-monsoon seasons. The outcome of the speciation analysis using MINTEQ indicated that free metal ions, carbonate, chloride and sulfate ions were predominantly in anionic inorganic fractions, while in cationic inorganic fractions metal loads were negligible. Metals loads were higher in sediment phase than in the aqueous phase. The estimated values of I geo in river sediment during both the seasons showed that most of the metals were found in the I geo class 0-1 which represents unpolluted to moderately polluted sediment status. The result of partition coefficient indicated the strong retention capability of Cr, Pb, Co and Mn, while Cd, Zn, Cu and Ni have resilient mobility capacity. The mineralogical analysis of sediment samples indicated that in Damodar River, quartz, kaolinite and calcite minerals were dominantly present. The hazard index values of Cd, Co and Cr were > 1 in river water, which suggested potential health risk for the children. A combination of pragmatic, computational and statistical relationship between ionic species and fractions of metals represented a strong persuasion for identifying the alikeness among the different sites of the river.

COMPETITIVE INFLUENCE OF PHOSPHORUS AND CALCIUM ON PB IN-VITRO BIOAVAILABILITY

EPA Science Inventory

The bioavailability of a metal is heavily related to the speciation of the particular metal. Further, the complexity of examining metal bioavailability is compounded by the presence of competitive ions. Thus, equally contaminated soils with varying concentrations of competitive e...

Temporal variability in trace metal solubility in a paddy soil not reflected in uptake by rice (Oryza sativa L.).

PubMed

Pan, Yunyu; Koopmans, Gerwin F; Bonten, Luc T C; Song, Jing; Luo, Yongming; Temminghoff, Erwin J M; Comans, Rob N J

2016-12-01

Alternating flooding and drainage conditions have a strong influence on redox chemistry and the solubility of trace metals in paddy soils. However, current knowledge of how the effects of water management on trace metal solubility are linked to trace metal uptake by rice plants over time is still limited. Here, a field-contaminated paddy soil was subjected to two flooding and drainage cycles in a pot experiment with two rice plant cultivars, exhibiting either high or low Cd accumulation characteristics. Flooding led to a strong vertical gradient in the redox potential (Eh). The pH and Mn, Fe, and dissolved organic carbon concentrations increased with decreasing Eh and vice versa. During flooding, trace metal solubility decreased markedly, probably due to sulfide mineral precipitation. Despite its low solubility, the Cd content in rice grains exceeded the food quality standards for both cultivars. Trace metal contents in different rice plant tissues (roots, stem, and leaves) increased at a constant rate during the first flooding and drainage cycle but decreased after reaching a maximum during the second cycle. As such, the high temporal variability in trace metal solubility was not reflected in trace metal uptake by rice plants over time. This might be due to the presence of aerobic conditions and a consequent higher trace metal solubility near the root surface, even during flooding. Trace metal solubility in the rhizosphere should be considered when linking water management to trace metal uptake by rice over time.

Issue Paper on the Environmental Chemistry of Metals

EPA Pesticide Factsheets

EPA has identified three types of regulatory risk assessments where information regarding speciation of metals is useful and desirable: national hazard/risk ranking and characterization, site-specific assessments, and National Regulatory Assessments.

Bioaccessibility, release kinetics, and molecular speciation of arsenic and lead in geo-dusts from the Iron King Mine Federal Superfund site in Humboldt, Arizona.

PubMed

Menka, Nazune; Root, Rob; Chorover, Jon

2014-01-01

Mine tailings contain multiple toxic metal(loid)s that pose a threat to human health via inhalation and ingestion. The goals of this research include understanding the speciation and molecular environment of these toxic metal(loid)s (arsenic and lead) as well as the impacts particle size and residence time have on their bioaccessibilty in simulated gastric and lung fluid. Additionally, future work will include smaller size fractions (PM10 and PM2.5) of surface mine tailings, with the goal of increasing our understanding of multi-metal release from contaminated geo-dusts in simulated bio-fluids. This research is important to environmental human health risk assessment as it increases the accuracy of exposure estimations to toxic metal(loid)s.

Phosphorus, Barium and Bioactive Metals (Zn, Cu, Co) in Coral Aragonite: Relationships to Upper Ocean Productivity

NASA Astrophysics Data System (ADS)

Sherrell, R. M.; Lavigne, M. G.; Linsley, B. K.

2006-12-01

Coral records of surface ocean properties related to primary productivity could reveal much about the history of upper ocean biogeochemistry over decades to centuries, but are currently relatively undeveloped. This presentation will explore the utility of high-resolution records of P/Ca, Ba/Ca, and the micronutrient metals Zn/Ca, Cu/Ca, and Co/Ca. Using high sensitivity laser ablation ICP-MS, we have obtained multi-year records of these variables with ~ bi-weekly resolution and seasonal dating for Porites corals from Rarotonga (21S, 159W) and Clipperton Atoll (10N, 109W) Results are compared to data for Porites and Acropora spp. grown in culture at Rutgers University, to explore the applicability of cultured corals for quantifying the effects of seawater chemistry on trace elements in coralline aragonite. The P/Ca results suggest lattice-bound incorporation and encourage the development of a surface ocean PO4 proxy details will be presented by LaVigne et al. elsewhere in this session. At Rarotonga, Ba/Ca shows regular, ~ annual, 2-5 week duration spikes a factor of 2-3 higher than the ~ constant background signal, appearing in austral spring- summer. These are not associated with runoff or authigenic mineral incorporation, and are similar to Ba spikes observed at least twice in the literature. We explore the hypothesis that these signals are related to biogenic organically-bound or barite Ba in the ambient surface water, and might therefore serve as a proxy of phytoplankton bloom intensity during the most productive part of the year. Potential mechanisms of incorporation must include the possibility of suspended particulate elements finding a route to permanent sequestration in the skeleton. Laser ablation values for Zn, and Cu are similar at Rarotonga and Clipperton, and higher by factors of 500 and 15 than literature values for cleaned aragonite analyzed in solution, while our Co/Ca values are the lowest ever determined. Seasonal and shorter scale variations at Rarotonga are muted for Zn, but substantial for Cu and Co, possibly reflecting biologically-driven changes in ambient dissolved metal concentration or speciation. Corals grown in non-metal clean artificial seawater are higher for Zn, but surprisingly lower for Cu and Co. We suggest that the distribution coefficient model of metal incorporation may need to be revised to include aspects of dissolved metal speciation and particulate metal sources. In sum, these results will be used to evaluate the utility of laser ablation data for revealing aspects of open ocean biogeochemistry in the past.

Arsenic Speciation and Cadmium Determination in Tobacco Leaves, Ash and Smoke.

PubMed

Iwai, Takahiro; Chiba, Koichi; Narukawa, Tomohiro

2016-01-01

The concentrations of arsenic (As) and cadmium (Cd) in the tobacco leaves, ash and smoke of 10 kinds of cigarettes collected from different countries worldwide were determined by ICP-MS after microwave-assisted digestion. Total As and Cd concentrations in the tobacco leaves ranged from 0.20 to 0.63 and 1.8 to 9.9 mg kg(-1), respectively. By the speciation analysis of As in tobacco leaves and ash by HPLC-ICP-MS following acid extraction, arsenite [As(III)] and arsenate [As(V)] were determined and trace amounts of monomethylarsonic acid (MMAA), dimethylarsinic acid (DMAA), trimethylarsine oxide (TMAO), tetramethylarsonium (TeMA) and some unidentified As species were also found. Arsenic speciation for smoke absorbed in an aqueous solution was carried out. The sum of the As species in tobacco leaves, ash and smoke was in good agreement with the result of total As determination in each sample, and the recoveries of speciation were 100 ± 10%. The distributions and the behaviors of As species were clarified.

Cesium Speciation in Dust from Municipal Solid Waste and Sewage Sludge Incineration by Synchrotron Radiation Micro-X-ray Analysis.

PubMed

Shiota, Kenji; Takaoka, Masaki; Fujimori, Takashi; Oshita, Kazuyuki; Terada, Yasuko

2015-11-17

The chemical behavior of Cs in waste incineration processes is important to consider when disposing of radionuclide-contaminated waste from the Fukushima Daiichi nuclear power plant accident in Japan. To determine the speciation of Cs, we attempted the direct speciation of trace amounts of stable Cs in the dust from municipal solid waste incineration (MSWI) and sewage sludge incineration (SSI) by micro-X-ray fluorescence (μ-XRF) and micro-X-ray absorption fine structure (μ-XAFS) at the SPring-8 facility. The μ-XRF results revealed that locally produced Cs was present in MSWI and SSI dust within the cluster size range of 2-10 μm. The μ-XAFS analysis confirmed that the speciation of Cs in MSWI dust was similar to that of CsCl, while in SSI dusts it was similar to pollucite. The solubility of Cs was considered to be influenced by the exact Cs species present in incineration residue.

BIOCHEM-ORCHESTRA: a tool for evaluating chemical speciation and ecotoxicological impacts of heavy metals on river flood plain systems.

PubMed

Vink, J P M; Meeussen, J C L

2007-08-01

The chemical speciation model BIOCHEM was extended with ecotoxicological transfer functions for uptake of metals (As, Cd, Cu, Ni, Pb, and Zn) by plants and soil invertebrates. It was coupled to the object-oriented framework ORCHESTRA to achieve a flexible and dynamic decision support system (DSS) to analyse natural or anthropogenic changes that occur in river systems. The DSS uses the chemical characteristics of soils and sediments as input, and calculates speciation and subsequent uptake by biota at various scenarios. Biotic transfer functions were field-validated, and actual hydrological conditions were derived from long-term monitoring data. The DSS was tested for several scenarios that occur in the Meuse catchment areas, such as flooding and sedimentation of riverine sediments on flood plains. Risks are expressed in terms of changes in chemical mobility, and uptake by flood plain key species (flora and fauna).

Predicting Metal Speciation & Bioavailability via Estimation of Metal-Organic Thermodynamic Properties

NASA Astrophysics Data System (ADS)

Prasad, A.; Howells, A. E.; Shock, E.

2017-12-01

The biological fate of any metal depends on its chemical form in the environment. Arsenic for example, is extremely toxic in the form of inorganic As+3 but completely benign in the organic form of arsenobetaine. Thus, given an exhaustive set of reactions and their equilibrium constants (logK), the bioavailability of any metal can be obtained for blood plasma, hydrothermal fluids or any system of interest. While many data exist for metal-inorganic ligands, logK data covering the temperature range of life for metal-organic complexes are sparse. Hence, we decided to estimate metal-organic logK values from correlations with the commonly available values of ligand pKa. Metal ion specific correlations were made with ligands classified according to their electron donor atoms, denticity and other chemical factors. While this approach has been employed before (Carbonaro et al. 2007, GCA 71, 3958-3968), new correlations were developed that provide estimates even when no metal-organic logK is available. In addition, we have used the same methods to make estimates of metal-organic entropy of association (ΔaS), which can provide logK for any temperature of biological relevance. Our current correlations employ logK and ΔaS data from 30 metal ions (like the biologically relevant Fe+3 & Zn+2) and 74 ligands (like formate and ethylenediamine), which can be expanded to estimate the metal-ligand reaction properties for these 30 metal ions with a possibly limitless number of ligands that may belong to our categories of ligands. With the help of such data, copper speciation was obtained for a defined growth medium for methanotrophs employed by Morton et al. (2000, AEM 66, 1730-1733) that agrees with experimental measurements showing that the free metal ion may not be the bioavailable form in all conditions. These results encourage us to keep filling the gaps in metal-organic logK data and continue finding relationships between biological responses (like metal-accumulation ratios & metal-induced toxicity) and metal speciation.

EFFECTS OF PH AND PHOSPHATE ON METAL DISTRIBUTION WITH EMPHASIS ON AS SPECIATION AND MOBILIZATION IN SOILS FROM A LEAD SMELTING SITE

EPA Science Inventory

Arsenic in soils from the Asarco Lead Smelter in East Helena, Montana was characterized by X-ray absorption spectroscopy (XAS). As oxidation state and geochemical speciation were analyzed as a function of depth (two sampling sites) and surface distribution. These results were c...

Zinc Speciation in Proximity to Phosphate Application Points in a Lead/Zinc Smelter-Contaminated Soil

EPA Science Inventory

The use of P to immobilize Pb in contaminated soils has been well documented. However, the influence of P on Zn speciation in soils has not been extensively examined, and these two metals often occur as co-contaminants. We hypothesized that additions of P to a Pb/Zn-contaminate...

Preconcentration and speciation of ultra-trace Se (IV) and Se (VI) in environmental water samples with nano-sized TiO2 colloid and determination by HG-AFS.

PubMed

Fu, Jiaqi; Zhang, Xu; Qian, Shahua; Zhang, Lin

2012-05-30

A united method for speciation analysis of Se (IV) and Se (VI) in environmental water samples was developed using nano-sized TiO(2) colloid as adsorbent and hydride generation atomic fluorescence spectrometry (HG-AFS) as determination means. When the pH values of bulk solution were between 6.0 and 7.0, successful adsorption onto 1 mL nano-sized TiO(2) colloid (0.2%) was achieved for more than 97.0% of Se (IV) while Se (VI) barely got adsorbed. Therefore, the method made it possible to preconcentrate and determine Se (IV) and Se (VI) separately. The precipitated TiO(2) with concentrated selenium was directly converted to colloid without desorption. Selenium in the resulting colloid was then determined by HG-AFS. The detection limits (3σ) and relative standard deviations (R.S.D) of this method were 24 ng/L and 42 ng/L, 7.8% (n=6) and 7.0% (n=6) for Se (IV) and Se (VI), respectively. This simple, sensitive, and united method was successfully applied to the separation and speciation of ultra-trace Se (IV) and Se (VI) in environmental water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Ligand exchange in ionic systems and its effect on silver nucleation and growth.

PubMed

Abbott, Andrew P; Azam, Muhammad; Frisch, Gero; Hartley, Jennifer; Ryder, Karl S; Saleem, Saima

2013-10-28

The electrodeposition of metals from ionic solutions is intrinsically linked to the reactivity of the solute ions. When metal salts dissolve, the exchange of the anion with the molecular and ionic components from solution affects the speciation and therefore the characteristics of metal reduction. This study investigates the nucleation mechanism, deposition kinetics, metal speciation and diffusion coefficients of silver salts dissolved in Deep Eutectic Solvents. The electrochemical reduction of AgCl, AgNO3 and Ag2O is studied in 1 : 2 choline chloride : ethylene glycol and 1 : 2 choline chloride : urea. Cyclic voltammetry is used to evaluate electrochemical kinetics. Detailed analysis of chronoamperometric data shows that silver deposits form via multiple 3D nucleation with mass transport controlled hemispherical growth. The nucleation mechanism was found to be potential dependent, varying from progressive to instantaneous as the reduction potential becomes more cathodic. Diffusion coefficients are determined using three different methods. Trends are rationalised in terms of solvent viscosity and silver speciation analysis with EXAFS. The morphology of electroreduced silver is investigated with scanning electron microscopy and shows that deposits from the urea based liquid form more dense morphologies than those from the ethylene glycol based liquid.

Bunker Hill Sediment Characterization Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neal A. Yancey; Debby F. Bruhn

2009-12-01

The long history of mineral extraction in the Coeur d’Alene Basin has left a legacy of heavy metal laden mine tailings that have accumulated along the Coeur d’Alene River and its tributaries (U.S. Environmental Protection Agency, 2001; Barton, 2002). Silver, lead and zinc were the primary metals of economic interest in the area, but the ores contained other elements that have become environmental hazards including zinc, cadmium, lead, arsenic, nickel, and copper. The metals have contaminated the water and sediments of Lake Coeur d’Alene, and continue to be transported downstream to Spokane Washington via the Spokane River. In 1983, themore » EPA listed the Bunker Hill Mining and Metallurgical Complex on the National Priorities List. Since that time, many of the most contaminated areas have been stabilized or isolated, however metal contaminants continue to migrate through the basin. Designation as a Superfund site causes significant problems for the economically depressed communities in the area. Identification of primary sources of contamination can help set priorities for cleanup and cleanup options, which can include source removal, water treatment or no action depending on knowledge about the mobility of contaminants relative to water flow. The mobility of contaminant mobility under natural or engineered conditions depends on multiple factors including the physical and chemical state (or speciation) of metals and the range of processes, some of which can be seasonal, that cause mobilization of metals. As a result, it is particularly important to understand metal speciation (National Research Council, 2005) and the link between speciation and the rates of metal migration and the impact of natural or engineered variations in flow, biological activity or water chemistry.« less

Use of synchrotron radiation to characterize metals in plants: the case of Cd in the hyperacumulator Arabidopsis halleri

NASA Astrophysics Data System (ADS)

Isaure, M.; Sarret, G.; Verbruggen, N.

2010-12-01

Phytoremediation uses plants to extract (phytoextraction) or stabilize (phytostabilization) metals accumulated in soils, and can be an alternative to invasive physico-chemical remediation techniques. Its development requires the knowledge of the mechanisms involved in metal tolerance and accumulation in plants, and particularly the way that plants transfer and store metals. In that context, synchrotron radiation based techniques such as micro-focused X-Ray Fluorescence (µXRF), and micro-focused X-ray Absorption Spectroscopy, including Extended X-ray Absorption Fine Structure and X-ray Absorption Near Edge Structure, are particularly suited to determine the localization and the chemical forms of metals in the different tissues, cells and sub-cellular compartments. Arabidopsis halleri is a Zn, Cd hyperaccumulating plant, naturally growing on contaminated sites, and is a model plant to investigate metal hyperaccumulation. This work presents the application of µXRF and Cd µXANES to determine the distribution and speciation of Cd in this species. Results showed that Cd was mainly located in the mesophyll and veins of leaves. It is bound to S ligands in some leaves and to O/N ligands in other ones, and the observed variations may be related to the age of the leaves. Cd speciation seems to differ from other metals, and particularly Zn, generally encountered in hyperaccumulators. High local Cd concentrations were also detected at the base of trichomes, epidermal hairs of leaves, associated to O/N ligands, probably to the cell wall. This phenomenon was also observed on non-hyperaccumulators and is clearly not the major sink for Cd, but trichomes might play a role in the detoxification process. This study illustrates the suitability of synchrotron radiation based techniques to investigate metal distribution and speciation in plants.

The deposition and fate of trace metals in our environment.

Treesearch

Elon S. Verry; Stephen J. Vermette

1992-01-01

This proceedings contains 14 invited papers from Canada and the United States on trace metal emissions, trace metal measurement in precipitation and dry fall, regional deposition, and the fate of trace metals in soils, plants, waters, and fish. A summary paper integrates the major findings of each paper.

COMPETITIVE INFLUENCE OF PHOSPHORUS AND CALCIUM ON PB IN-VITRO BIOAVAILABILITY (S11-SCHECKEL101231-POSTER)

EPA Science Inventory

The bioavailability of a metal is heavily related to the speciation of the particular metal. Further, the complexity of examining metal bioavailability is compounded by the presence of competitive ions. Thus, equally contaminated soils with varying concentrations of competitive e...

Iron solubility driven by speciation in dust sources to the ocean

USGS Publications Warehouse

Schroth, A.W.; Crusius, John; Sholkovitz, E.R.; Bostick, B.C.

2009-01-01

Although abundant in the Earths crust, iron is present at trace concentrations in sea water and is a limiting nutrient for phytoplankton in approximately 40% of the ocean. Current literature suggests that aerosols are the primary external source of iron to offshore waters, yet controls on iron aerosol solubility remain unclear. Here we demonstrate that iron speciation (oxidation state and bonding environment) drives iron solubility in arid region soils, glacial weathering products (flour) and oil combustion products (oil fly ash). Iron speciation varies by aerosol source, with soils in arid regions dominated by ferric (oxy)hydroxides, glacial flour by primary and secondary ferrous silicates and oil fly ash by ferric sulphate salts. Variation in iron speciation produces systematic differences in iron solubility: less than 1% of the iron in arid soils was soluble, compared with 2-3% in glacial products and 77-81% in oil combustion products, which is directly linked to fractions of more soluble phases. We conclude that spatial and temporal variations in aerosol iron speciation, driven by the distribution of deserts, glaciers and fossil-fuel combustion, could have a pronounced effect on aerosol iron solubility and therefore on biological productivity and the carbon cycle in the ocean. ?? 2009 Macmillan Publishers Limited.

BIOLOGICAL MONITORING OF TOXIC TRACE METALS. VOLUME 2. TOXIC TRACE METALS IN PLANTS AND ANIMALS OF THE WORLD. PART II

EPA Science Inventory

The needs and priorities in using biological accumulator organisms for monitoring toxic trace metals in plants and animals are analyzed. The toxic trace metals selected for study are antimony, arsenic, beryllium, boron, cadmium, chromium, cobalt, copper, lead, mercury, nickel, se...

BIOLOGICAL MONITORING OF TOXIC TRACE METALS. VOLUME 2. TOXIC TRACE METALS IN PLANTS AND ANIMALS OF THE WORLD. PART I

EPA Science Inventory

The needs and priorities in using biological accumulator organisms for monitoring toxic trace metals in plants and animals are analyzed. The toxic trace metals selected for study are antimony, arsenic, beryllium, boron, cadmium, chromium, cobalt, copper, lead, mercury, nickel, se...

Distribution of Cd, Pb, Zn and Cu and their chemical speciations in soils from a peri-smelter area in northeast China

NASA Astrophysics Data System (ADS)

Du, Ping; Xue, Nandong; Liu, Li; Li, Fasheng

2008-07-01

An exploratory study on soil contamination of heavy metals was carried out surrounding Huludao zinc smelter in Liaoning province, China. The distribution of total heavy metals and their chemical speciations were investigated. The correlations between heavy metal speciations and soil pH values in corresponding sites were also analyzed. In general, Cd, Zn, Pb, Cu and As presented a significant contamination in the area near the smelter, comparied with Environmental Quality Standards for Soils in China. The geoaccumulation index showed the degree of contamination: Cd > Zn > Pb > Cu > As. There was no obvious pollution of Cr and Ni in the studied area. The speciation analysis showed that the dominant fraction of Cd and Zn was the acid soluble fraction, and the second was the residual fraction. Pb was mostly associated with the residual fraction, which constituted more than 50% of total concentration in all samples. Cu in residual fraction accounted for a high percentage (40-80%) of total concentration, and the proportion of Cu in the oxidizable fraction is higher than that of other metals. The distribution pattern of Pb and Zn was obviously affected by soil pH. It seemed that Pb and Zn content in acid solution fraction increased with increasing soil pH values, while Cd content in acid soluble fraction accounted for more proportion in neutral and alkaline groups than acidic one. The fraction distribution patterns of Cu in three pH groups were very similar and independent of soil pH values. And the residual fraction of Cu took a predominant part (50%) of the total content.

Ultra-sensitive speciation analysis of mercury by CE-ICP-MS together with field-amplified sample stacking injection and dispersive solid-phase extraction.

PubMed

Chen, YiQuan; Cheng, Xian; Mo, Fan; Huang, LiMei; Wu, Zujian; Wu, Yongning; Xu, LiangJun; Fu, FengFu

2016-04-01

A simple dispersive solid-phase extraction (DSPE) used to extract and preconcentrate ultra-trace MeHg, EtHg and Hg(2+) from water sample, and a sensitive method for the simultaneous analysis of MeHg, EtHg and Hg(2+) by using capillary electrophoresis-inductively coupled plasma mass spectrometry (CE-ICP-MS) with field-amplified sample stacking injection (FASI) were first reported in this study. The DSPE used thiol cotton particles as adsorbent, and is simple and effective. It can be used to extract and preconcentrate ultra-trace mercury compounds in water samples within 30 min with a satisfied recovery and no mercury species alteration during the process. The FASI enhanced the sensitivity of CE-ICP-MS with 25-fold, 29-fold and 27-fold for MeHg, EtHg and Hg(2+) , respectively. Using FASI-CE-ICP-MS together with DSPE, we have successfully determined ultra-trace MeHg, EtHg and Hg(2+) in tap water with a limits of quantification (LOQs) of 0.26-0.45 pg/mL, an RSD (n = 3) < 6% and a recovery of 92-108%. Ultra-high sensitivity, as well as much less sample and reagent consumption and low operating cost, make our method a valuable technique to the speciation analysis of ultra-trace mercury. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Statistical analysis of iron geochemical data suggests limited late Proterozoic oxygenation

NASA Astrophysics Data System (ADS)

Sperling, Erik A.; Wolock, Charles J.; Morgan, Alex S.; Gill, Benjamin C.; Kunzmann, Marcus; Halverson, Galen P.; MacDonald, Francis A.; Knoll, Andrew H.; Johnston, David T.

2015-07-01

Sedimentary rocks deposited across the Proterozoic-Phanerozoic transition record extreme climate fluctuations, a potential rise in atmospheric oxygen or re-organization of the seafloor redox landscape, and the initial diversification of animals. It is widely assumed that the inferred redox change facilitated the observed trends in biodiversity. Establishing this palaeoenvironmental context, however, requires that changes in marine redox structure be tracked by means of geochemical proxies and translated into estimates of atmospheric oxygen. Iron-based proxies are among the most effective tools for tracking the redox chemistry of ancient oceans. These proxies are inherently local, but have global implications when analysed collectively and statistically. Here we analyse about 4,700 iron-speciation measurements from shales 2,300 to 360 million years old. Our statistical analyses suggest that subsurface water masses in mid-Proterozoic oceans were predominantly anoxic and ferruginous (depleted in dissolved oxygen and iron-bearing), but with a tendency towards euxinia (sulfide-bearing) that is not observed in the Neoproterozoic era. Analyses further indicate that early animals did not experience appreciable benthic sulfide stress. Finally, unlike proxies based on redox-sensitive trace-metal abundances, iron geochemical data do not show a statistically significant change in oxygen content through the Ediacaran and Cambrian periods, sharply constraining the magnitude of the end-Proterozoic oxygen increase. Indeed, this re-analysis of trace-metal data is consistent with oxygenation continuing well into the Palaeozoic era. Therefore, if changing redox conditions facilitated animal diversification, it did so through a limited rise in oxygen past critical functional and ecological thresholds, as is seen in modern oxygen minimum zone benthic animal communities.

Competitive adsorption of heavy metals in soil underlying an infiltration facility installed in an urban area.

PubMed

Hossain, M A; Furumai, H; Nakajima, F

2009-01-01

Accumulation of heavy metals at elevated concentration and potential of considerable amount of the accumulated heavy metals to reach the soil system was observed from earlier studies in soakaways sediments within an infiltration facility in Tokyo, Japan. In order to understand the competitive adsorption behaviour of heavy metals Zn, Ni and Cu in soil, competitive batch adsorption experiments were carried out using single metal and binary metal combinations on soil samples representative of underlying soil and surface soil at the site. Speciation analysis of the adsorbed metals was carried out through BCR sequential extraction method. Among the metals, Cu was not affected by competition while Zn and Ni were affected by competition of coexisting metals. The parameters of fitted 'Freundlich' and 'Langmuir' isotherms indicated more intense competition in underlying soil compared to surface soil for adsorption of Zn and Ni. The speciation of adsorbed metals revealed less selectivity of Zn and Ni to soil organic matter, while dominance of organic bound fraction was observed for Cu, especially in organic rich surface soil. Compared to underlying soil, the surface soil is expected to provide greater adsorption to heavy metals as well as provide greater stability to adsorbed metals, especially for Cu.

Kinetics of steel slag leaching: Batch tests and modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Windt, Laurent, E-mail: laurent.dewindt@mines-paristech.fr; Chaurand, Perrine; Rose, Jerome

2011-02-15

Reusing steel slag as an aggregate for road construction requires to characterize the leaching kinetics and metal releases. In this study, basic oxygen furnace (BOF) steel slag were subjected to batch leaching tests at liquid to solid ratios (L/S) of 10 and 100 over 30 days; the leachate chemistry being regularly sampled in time. A geochemical model of the steel slag is developed and validated from experimental data, particularly the evolution with leaching of mineralogical composition of the slag and trace element speciation. Kinetics is necessary for modeling the primary phase leaching, whereas a simple thermodynamic equilibrium approach can bemore » used for secondary phase precipitation. The proposed model simulates the kinetically-controlled dissolution (hydrolysis) of primary phases, the precipitation of secondary phases (C-S-H, hydroxide and spinel), the pH and redox conditions, and the progressive release of major elements as well as the metals Cr and V. Modeling indicates that the dilution effect of the L/S ratio is often coupled to solubility-controlled processes, which are sensitive to both the pH and the redox potential. A sensitivity analysis of kinetic uncertainties on the modeling of element releases is performed.« less

Manipulation and measurement of pH sensitive metal-ligand binding using electrochemical proton generation and metal detection.

PubMed

Read, Tania L; Joseph, Maxim B; Macpherson, Julie V

2016-01-31

Generator-detector electrodes can be used to both perturb and monitor pH dependant metal-ligand binding equilibria, in situ. In particular, protons generated at the generator locally influence the speciation of metal (Cu(2+)) in the presence of ligand (triethylenetetraamine), with the detector employed to monitor, in real time, free metal (Cu(2+)) concentrations.

Geochemical partitioning of Cu and Ni in mangrove sediments: relationships with their bioavailability.

PubMed

Chakraborty, Parthasarathi; Ramteke, Darwin; Chakraborty, Sucharita

2015-04-15

Sequential extraction study was performed to determine the concentrations of non-residual metal-complexes in the mangrove sediments from the Divar Island, (west coast of India). Accumulation of metal in the mangrove roots (from the same location) was determined and used as an indicator of bioavailability of metal. An attempt was made to establish a mechanistic linkage between the non-residual metal complexes and their bioavailability in the mangrove system. The non-residual fractions of Cu and Ni were mainly associated with Fe/Mn oxyhydroxide and organic phases in the sediments. A part of these metal fractions were bioavailable in the system. These two phases were the major controlling factors for Ni speciation and their bioavailability in the studied sediments. However, Cu was found to interact more strongly with the organic phases than Ni in the mangrove sediments. Organic phases in the mangrove sediments acted as buffer to control the speciation and bioavailability of Cu in the system. Copyright © 2015 Elsevier Ltd. All rights reserved.

Speciation and distribution of cadmium and lead in salinized horizons of antrosols

NASA Astrophysics Data System (ADS)

Bulgariu, D.; Bulgariu, L.; Astefanei, D.

2009-04-01

The utilization of intensive technologies for the vegetable cultivation in glass houses by the administration of high doses of organic fertilizes, the supra-dimensional irrigation and the maintaining of soil at high humidity state, in special in case of vicious drainage have as result the rapid degradation of morphological, chemical and physical characteristics of soils, concretized by: (i) decrease of structural aggregates stability; (ii) more dense packing of soil; (iii) accumulation of easy soluble salts (in special at superior horizons level); (iv) limitation of organic compounds and micro-elements biodisponibility. All these determined a significant reduction of productivity and of exploitation duration of soils from glass houses. These phenomena modified continuously the dynamic of speciation processes and inter-phases distribution, of heavy metals in soils from glass houses, and can determined a non-controlled accumulation of heavy metals, in special as mobile forms with high biodisponibility. Ours studied have been performed using soil profiles drawing from Copou-glass house, Iasi (Romania). Has been followed the modification of distribution for speciation forms of cadmium and lead (two heavy metals with high toxicity degree), between hortic antrosol horizons, and between chemical-mineralogical components of this, with the progressive salinization of superior horizons, in 2007-2008 period. The separation, differentiation and determination of cadmium and lead speciation forms was done by combined solid-liquid sequential extraction (SPE) and extraction in aqueous polymer-inorganic salt two-phase systems (ABS) procedure, presented in some of ours previous studies. After extraction, the total contents of the two heavy metals and fractions from these differential bonded by mineral and organic components of hortic antrosol have been determined by atomic absorption spectrometry. The specific interaction mechanisms of Cd and Pb with organic-mineral components of soils have been estimated on the basis of Raman and FT-IR spectra, recorded for fractions obtained after each extraction step. These data were correlated with those obtained by chemical analysis and UV-VIS spectrometry, and were used for to establish the type and weight of Cd and Pb speciation forms in studied antrosol. Our studies have been show that in medium and inferior horizons of hortic antrosols, the heavy metals have a general accumulation tendency, preferential by binding on organic matter and organic-mineral complexes, components with higher abundance in such type of soils. The selectivity and complexation mechanisms are controlled by speciation forms of the two metals. This phenomenon has two important consequences, the strong fixation of heavy metals in hortic antrosol and significant modification of structure and conformation of organic macromolecules. A specific phenomenon of hortic antrosols is that the accumulation rate of heavy metals is higher than levigation rate, and the mobile forms of these have a higher biodisponibility, being relative easy assimilated by plants. The progressive salinization of superior horizons of soils from glass houses, determined a sever perturbation of equilibrium between Cd and Pb speciation forms. In consequence these will have an accentuated migration tendency in superior horizons, as complexes with inorganic ligands, with a high mobility and biodsiponibility. The accumulation of soluble salts in superior horizons, and the formation of frangipane horizon (horizon of geochemical segregation of hortic antrosols) modified the ionic strength from soil solution and the thermodynamic activity of cadmium and lead species. Under these conditions, the levigation rate of cadmium and lead is higher than the accumulation rate, which means that the migration of these metals in soil solution occurs fast and in high concentrations. Acknowledgments The authors would like to acknowledge the financial support from Romanian Ministry of Education and Research (Project PNCDI 2-D5 no. 51045/07 an Project PNCDI 2-D5 no. 52141 / 08).

THE WEATHERING OF A SULFIDE OREBODY: SPECIATION AND FATE OF SOME POTENTIAL CONTAMINANTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Courtin-Nomade, Alexandra; Grosbois, Cecile; Marcus, Matthew A.

2010-07-16

Various potentially toxic trace elements such as As, Cu, Pb and Zn have been remobilized by the weathering of a sulfide orebody that was only partially mined at Leona Heights, California. As a result, this body has both natural and anthropogenically modified weathering profiles only 500 m apart. The orebody is located in a heavily urbanized area in suburban Oakland, and directly affects water quality in at least one stream by producing acidic conditions and relatively high concentrations of dissolved elements (e.g., {approx}500 mg/L Cu, {approx}3700 mg/L Zn). Micrometric-scale mineralogical investigations were performed on the authigenic metal-bearing phases (less thanmore » 10 {mu}m in size) using electron-probe micro-analysis (EPMA), micro-Raman, micro X-ray absorption spectroscopy (mXAS), scanning X-ray diffraction (mSXRD) and scanning X-ray fluorescence (mSXRF) mapping techniques. Those measurements were coupled with classical mineralogical laboratory techniques, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Authigenic metal-bearing phases identified are mainly sulfates (jarosite, epsomite, schwertmannite), Fe (oxy-)hydroxides (goethite, hematite and poorly crystalline Fe products) and poorly crystalline Mn (hydr-)oxides. Sulfates and Fe (oxy-)hydroxides are the two main secondary products at both sites, whereas Mn (hydr-) oxides were only observed in the samples from the non-mining site. In these samples, the various trace elements show different affinities for Fe or Mn compounds. Lead is preferentially associated with Mn (hydr-)oxides and As with Fe (oxy-)hydroxides or sulfates. Copper association with Mn and Fe phases is questionable, and the results obtained rather indicate that Cu is present as individual Cu-rich grains (Cu hydroxides). Some ochreous precipitates were found at both sites and correspond to a mixture of schwertmannite, goethite and jarosite containing some potentially toxic trace elements such as Cu, Pb and Zn. According to the trace element distribution and relative abundance of the unweathered sulfides, this orebody still represents a significant reservoir of potential contaminants for the watershed, especially in the non-mining site, as a much greater proportion of sulfides is left to react and because of the lower porosity in this site.« less

The weathering of a sulfide orebody: Speciation and fate of some potential contaminants

USGS Publications Warehouse

Courtin-Nomade, A.; Grosbois, C.; Marcus, M.A.; Fakra, S.C.; Beny, J.-M.; Foster, A.L.

2009-01-01

Various potentially toxic trace elements such as As, Cu, Pb and Zn have been remobilized by the weathering of a sulfide orebody that was only partially mined at Leona Heights, California. As a result, this body has both natural and anthropogeni- cally modified weathering profiles only 500 m apart. The orebody is located in a heavily urbanized area in suburban Oakland, and directly affects water quality in at least one stream by producing acidic conditions and relatively high concentrations of dissolved elements (e.g., ??500 ??g/L Cu, ??3700 ??g/L Zn). Micrometric-scale mineralogical investigations were performed on the authigenic metal-bearing phases (less than 10 ??m in size) using electron-probe micro-analysis (EPMA), micro-Raman, micro X-ray absorption spectroscopy (??XAS), scanning X-ray diffraction ((??SXRD) and scanning X-ray fluorescence (??-SXRF) mapping techniques. Those measurements were coupled with classical mineralogical laboratory techniques, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Authigenic metal-bearing phases identified are mainly sulfates (jarosite, epsomite, schwertmannite), Fe (oxy-)hydroxides (goethite, hematite and poorly crystalline Fe products) and poorly crystalline Mn (hydr-)oxides. Sulfates and Fe (oxy-)hydroxides are the two main secondary products at both sites, whereas Mn (hydr-) oxides were only observed in the samples from the non-mining site. In these samples, the various trace elements show different affinities for Fe or Mn compounds. Lead is preferentially associated with Mn (hydr-)oxides and As with Fe (oxy-)hydroxides or sulfates. Copper association with Mn and Fe phases is questionable, and the results obtained rather indicate that Cu is present as individual Cu-rich grains (Cu hydroxides). Some ochreous precipitates were found at both sites and correspond to a mixture of schwertmannite, goethite and jarosite containing some potentially toxic trace elements such as Cu, Pb and Zn. According to the trace element distribution and relative abundance of the unweathered sulfides, this orebody still represents a significant reservoir of potential contaminants for the watershed, especially at the non-mining site, as a much greater proportion of sulfides is left to react and because of the lower porosity at this site.

Influence of a soil enzyme on iron-cyanide complex speciation and mineral adsorption.

PubMed

Zimmerman, Andrew R; Kang, Dong-Hee; Ahn, Mi-Youn; Hyun, Seunghun; Banks, M Katherine

2008-01-01

Cyanide is commonly found as ferrocyanide [Fe(II)(CN)(6)](-4) and in the more mobile form, ferricyanide [Fe(III)(CN)(6)](-3) in contaminated soils and sediments. Although soil minerals may influence ferrocyanide speciation, and thus mobility, the possible influence of soil enzymes has not been examined. In a series of experiments conducted under a range of soil-like conditions, laccase, a phenoloxidase enzyme derived from the fungi Trametes versicolor, was found to exert a large influence on iron-cyanide speciation and mobility. In the presence of laccase, up to 93% of ferrocyanide (36-362ppm) was oxidized to ferricyanide within 4h. No significant effect of pH (3.6 and 6.2) or initial ferrocyanide concentration on the extent or rate of oxidation was found and ferrocyanide oxidation did not occur in the absence of laccase. Relative to iron-cyanide-mineral systems without laccase, ferrocyanide adsorption to aluminum hydroxide and montmorillonite decreased in the presence of laccase and was similar to or somewhat greater than that of ferricyanide without laccase. Laccase-catalyzed conversion of ferrocyanide to ferricyanide was extensive though up to 33% of the enzyme was mineral-bound. These results demonstrate that soil enzymes can play a major role in ferrocyanide speciation and mobility. Biotic soil components must be considered as highly effective oxidation catalysts that may alter the mobility of metals and metal complexes in soil. Immobilized enzymes should also be considered for use in soil metal remediation efforts.

Impact of trace metal concentrations on coccolithophore growth and morphology: species-specific responses in past and present ocean

NASA Astrophysics Data System (ADS)

Faucher, Giulia; Hoffmann, Linn; Bach, Lennart Thomas; Bottini, Cinzia; Erba, Elisabetta; Riebesell, Ulf

2017-04-01

The Cretaceous witnessed intervals of profound perturbation named "Oceanic Anoxic Events (OAEs)" characterized by volcanic injection of large amounts of CO2, ocean anoxia, eutrophication, and introduction of biologically relevant metals. Some of these extreme events were characterized by size reduction and/or morphological changes of a number of nannofossil species. To detect the cause/s of such changes in the fossil record is challenging. Evidence of a correspondence between intervals of high trace metals concentrations and nannofossil dwarfism may be suggestive for a negative effect of these elements on nannoplankton biocalcification process. In order to verify the hypothesis that anomalously high quantities of essential and/or toxic metals were the cause of coccolith dwarfism, we explored the toxicities of a mixture of trace metals on four living coccolithophores species, namely Emiliania huxleyi, Gephyrocapsa oceanica, Pleurochrysis carterae and Coccolithus pelagicus. The trace metals tested were chosen based upon concentration peaks identified in the geological record and upon known trace metal interaction with living coccolithophores algae. Our results demonstrate a species-specific response to trace metal enrichment in living coccolithophores: E. huxleyi, G. oceanica and C. pelagicus showed a decrease in their growth rate with progressively and exponentially increased trace metal concentrations, while P. carterae is unresponsive to trace metal content. Furthermore, E. huxleyi, G. oceanica and C. pelagicus evidenced a decrease in the cell diameter. Smaller coccoliths were detected in E. huxleyi and C. pelagicus, while coccolith of G. oceanica showed a decrease in size only at the highest trace metal concentrations tested. P. carterae size was unresponsive for changing trace metal concentration. Our results on living coccolithophore algae, demonstrate that elevated trace metal concentrations not only affect growth but also coccolith size and/or weight and that there are large differences between different species. These species-specific differences must be considered before morphological features of coccoliths are used to reconstruct paleo-chemical conditions. Following the laboratory experiment results, elevated trace metal conditions in the past oceans could have caused at least part of the observed morphological changes detected during some Mesozoic OAEs.

Distribution, speciation, environmental risk, and source identification of heavy metals in surface sediments from the karst aquatic environment of the Lijiang River, Southwest China.

PubMed

Xu, Daoquan; Wang, Yinghui; Zhang, Ruijie; Guo, Jing; Zhang, Wei; Yu, Kefu

2016-05-01

The distribution and speciation of several heavy metals, i.e., As, Cd, Cr, Cu, Hg, Pb, and Zn, in surface sediments from the karst aquatic environment of the Lijiang River, Southwest China, were studied comparatively. The mean contents of Cd, Cu, Hg, Pb, and Zn were 1.72, 38.07, 0.18, 51.54, and 142.16 mg/kg, respectively, which were about 1.5-6 times higher than their corresponding regional sediment background values. Metal speciation obtained by the optimized BCR protocol highlighted the bioavailable threats of Cd, Cu, and Zn, which were highly associated with the exchangeable fraction (the labile phase). Hierarchical cluster analysis indicated that in sediments, As and Cr were mainly derived from natural and industrial sources, whereas fertilizer application might lead to the elevated level of Cd. Besides, Cu, Hg, Pb, and Zn were related to traffic activities. The effects-based sediment quality guidelines (SQGs) showed that Hg, Pb, and Zn could pose occasional adverse effects on sediment-dwelling organisms. However, based on the potential ecological risk assessment (PER) and risk assessment code (RAC), Cd was the most outstanding pollutant and posed the highest ecological hazard and bioavailable risk among the selected metals. Moreover, the metal partitioning between water and sediments was quantified through the calculation of the pseudo-partitioning coefficient (K P), and result implied that the sediments in this karst aquatic environment cannot be used as stable repositories for the metal pollutants.

Resolving colocalization of bacteria and metal(loid)s on plant root surfaces by combining fluorescence in situ hybridization (FISH) with multiple-energy micro-focused X-ray fluorescence (ME μXRF).

PubMed

Honeker, Linnea K; Root, Robert A; Chorover, Jon; Maier, Raina M

2016-12-01

Metal(loid)-contamination of the environment due to anthropogenic activities is a global problem. Understanding the fate of contaminants requires elucidation of biotic and abiotic factors that influence metal(loid) speciation from molecular to field scales. Improved methods are needed to assess micro-scale processes, such as those occurring at biogeochemical interfaces between plant tissues, microbial cells, and metal(loid)s. Here we present an advanced method that combines fluorescence in situ hybridization (FISH) with synchrotron-based multiple-energy micro-focused X-ray fluorescence microprobe imaging (ME μXRF) to examine colocalization of bacteria and metal(loid)s on root surfaces of plants used to phytostabilize metalliferous mine tailings. Bacteria were visualized on a small root section using SytoBC nucleic acid stain and FISH probes targeting the domain Bacteria and a specific group (Alphaproteobacteria, Gammaproteobacteria, or Actinobacteria). The same root region was then analyzed for elemental distribution and metal(loid) speciation of As and Fe using ME μXRF. The FISH and ME μXRF images were aligned using ImageJ software to correlate microbiological and geochemical results. Results from quantitative analysis of colocalization show a significantly higher fraction of As colocalized with Fe-oxide plaques on the root surfaces (fraction of overlap 0.49±0.19) than to bacteria (0.072±0.052) (p<0.05). Of the bacteria that colocalized with metal(loid)s, Actinobacteria, known for their metal tolerance, had a higher correlation with both As and Fe than Alphaproteobacteria or Gammaproteobacteria. This method demonstrates how coupling these micro-techniques can expand our understanding of micro-scale interactions between roots, metal(loid)s and microbes, information that should lead to improved mechanistic models of metal(loid) speciation and fate. Copyright © 2016 Elsevier B.V. All rights reserved.

Source-specific speciation profiles of PM2.5 for heavy metals and their anthropogenic emissions in China.

PubMed

Liu, Yayong; Xing, Jia; Wang, Shuxiao; Fu, Xiao; Zheng, Haotian

2018-08-01

Heavy metals are concerned for its adverse effect on human health and long term burden on biogeochemical cycling in the ecosystem. In this study, a provincial-level emission inventory of 13 kinds of heavy metals including V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Sn, Sb, Ba and Pb from 10 anthropogenic sources was developed for China, based on the 2015 national emission inventory of primary particulate matters and source category-specific speciation profiles collected from 50 previous studies measured in China. Uncertainties associated with the speciation profiles were also evaluated. Our results suggested that total emissions of the 13 types of heavy metals in China are estimated at about 58000 ton for the year 2015. The iron production is the dominant source of heavy metal, contributing 42% of total emissions of heavy metals. The emissions of heavy metals vary significantly at regional scale, with largest amount of emissions concentrated in northern and eastern China. Particular, high emissions of Cr, Co, Ni, As and Sb (contributing 8%-18% of the national emissions) are found in Shandong where has large capacity of industrial production. Uncertainty analysis suggested that the implementation of province-specific source profiles in this study significantly reduced the emission uncertainties from (-89%, 289%) to (-99%, 91%), particularly for coal combustion. However, source profiles for industry sectors such as non-metallic mineral manufacturing are quite limited, resulting in a relative high uncertainty. The high-resolution emission inventories of heavy metals are essential not only for their distribution, deposition and transport studies, but for the design of policies to redress critical atmospheric environmental hazards at local and regional scales. Detailed investigation on source-specific profile in China are still needed to achieve more accurate estimations of heavy metals in the future. Copyright © 2018 Elsevier Ltd. All rights reserved.

Chemical speciation and mobilization of copper and zinc in naturally contaminated mine soils with citric and tartaric acids.

PubMed

Pérez-Esteban, Javier; Escolástico, Consuelo; Moliner, Ana; Masaguer, Alberto

2013-01-01

A one-step extraction procedure and a leaching column experiment were performed to assess the effects of citric and tartaric acids on Cu and Zn mobilization in naturally contaminated mine soils to facilitate assisted phytoextraction. A speciation modeling of the soil solution and the metal fractionation of soils were performed to elucidate the chemical processes that affected metal desorption by organic acids. Different extracting solutions were prepared, all of which contained 0.01 M KNO(3) and different concentrations of organic acids: control without organic acids, 0.5 mM citric, 0.5 mM tartaric, 10 mM citric, 10 mM tartaric, and 5 mM citric +5 mM tartaric. The results of the extraction procedure showed that higher concentrations of organic acids increased metal desorption, and citric acid was more effective at facilitating metal desorption than tartaric acid. Metal desorption was mainly influenced by the decreasing pH and the dissolution of Fe and Mn oxides, not by the formation of soluble metal-organic complexes as was predicted by the speciation modeling. The results of the column study reported that low concentrations of organic acids did not significantly increase metal mobilization and that higher doses were also not able to mobilize Zn. However, 5-10 mM citric acid significantly promoted Cu mobilization (from 1 mg kg(-1) in the control to 42 mg kg(-1) with 10 mM citric acid) and reduced the exchangeable (from 21 to 3 mg kg(-1)) and the Fe and Mn oxides (from 443 to 277 mg kg(-1)) fractions. Citric acid could efficiently facilitate assisted phytoextraction techniques. Copyright © 2012 Elsevier Ltd. All rights reserved.

Sediment quality in Burlington Harbor, Lake Champlain, U.S.A.

USGS Publications Warehouse

Lacey, E.M.; King, J.W.; Quinn, J.G.; Mecray, E.L.; Appleby, P.G.; Hunt, A.S.

2001-01-01

Surface samples and cores were collected in 1993 from the Burlington Harbor region of Lake Champlain. Sediment samples were analyzed for trace metals (cadmium, copper, lead, nickel, silver and zinc), simultaneously extracted metal/acid volatile sulfide (SEM-AVS), grain size, nutrients (carbon and nitrogen) and organic contaminants (polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs)). The concentrations of cadmium, copper, silver and zinc from the partial sediment digestion of the surface samples correlated well with each other (r2 > 0.60) indicating that either a common process, or group of processes determined the sediment concentrations of these metals. In an analysis of the spatial distribution of the trace metals and PAHs, high surficial concentrations were present in the southern portion of the Harbor. The trace metal trend was strengthened when the concentrations were normalized by grain size. A sewage treatment plant outfall discharge was present in the southeastern portion of the Harbor at the time of this study and is the major source of trace metal and PAH contamination. Evaluation of sediment cores provides a proxy record of historical trace metal and organic inputs. The peak accumulation rate for copper, cadmium, lead, and zinc was in the late 1960s and the peak silver accumulation rate was later. The greatest accumulation of trace metals occurred in the late 1960s after discharges from the STP began. Subsequent declines in trace metal concentrations may be attributed to increased water and air regulations. The potential toxicity of trace metals and organic contaminants was predicted by comparing contaminant concentrations to benchmark concentrations and potential trace metal bioavailability was predicted with SEM-AVS results. Surface sample results indicate lead, silver, ???PAHs and ???PCBs are potentially toxic and/or bioavailable. These predictions were supported by studies of biota in the Burlington Harbor watershed. There is a clear trend of decreasing PAH and trace metal contaminant concentrations with distance from the STP outfall.Surface samples and cores were collected in 1993 from the Burlington Harbor region of Lake Champlain. Sediment samples were analyzed for trace metals (cadmium, copper, lead, nickel, silver and zinc), simultaneously extracted metal/acid volatile sulfide (SEM-AVS), grain size, nutrients (carbon and nitrogen) and organic contaminants (polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs)). The concentrations of cadmium, copper, silver and zinc from the partial sediment digestion of the surface samples correlated well with each other (r2>0.60) indicating that either a common process, or group of processes determined the sediment concentrations of these metals. In an analysis of the spatial distribution of the trace metals and PAHs, high surficial concentrations were present in the southern portion of the Harbor. The trace metal trend was strengthened when the concentrations were normalized by grain size. A sewage treatment plant outfall discharge was present in the southeastern portion of the Harbor at the time of this study and is the major source of trace metal and PAH contamination. Evaluation of sediment cores provides a proxy record of historical trace metal and organic inputs. The peak accumulation rate for copper, cadmium, lead, and zinc was in the late 1960s and the peak silver accumulation rate was later. The greatest accumulation of trace metals occurred in the late 1960s after discharges from the STP began. Subsequent declines in trace metal concentrations may be attributed to increased water and air regulations. The potential toxicity of trace metals and organic contaminants was predicted by comparing contaminant concentrations to benchmark concentrations and potential trace metal bioavailability was predicted with SEM-AVS results. Surface sample results indicate lead, silver, ??PAHs and ??PCBs are potentially toxic and/or bi

Particle-size dependence on metal(loid) distributions in mine wastes: Implications for water contamination and human exposure

USGS Publications Warehouse

Kim, C.S.; Wilson, K.M.; Rytuba, J.J.

2011-01-01

The mining and processing of metal-bearing ores has resulted in contamination issues where waste materials from abandoned mines remain in piles of untreated and unconsolidated material, posing the potential for waterborne and airborne transport of toxic elements. This study presents a systematic method of particle size separation, mass distribution, and bulk chemical analysis for mine tailings and adjacent background soil samples from the Rand historic mining district, California, in order to assess particle size distribution and related trends in metal(loid) concentration as a function of particle size. Mine tailings produced through stamp milling and leaching processes were found to have both a narrower and finer particle size distribution than background samples, with significant fractions of particles available in a size range (???250 ??m) that could be incidentally ingested. In both tailings and background samples, the majority of trace metal(loid)s display an inverse relationship between concentration and particle size, resulting in higher proportions of As, Cr, Cu, Pb and Zn in finer-sized fractions which are more susceptible to both water- and wind-borne transport as well as ingestion and/or inhalation. Established regulatory screening levels for such elements may, therefore, significantly underestimate potential exposure risk if relying solely on bulk sample concentrations to guide remediation decisions. Correlations in elemental concentration trends (such as between As and Fe) indicate relationships between elements that may be relevant to their chemical speciation. ?? 2011 Elsevier Ltd.

Advanced Elemental and Isotopic Characterization of Atmospheric Aerosols

NASA Astrophysics Data System (ADS)

Shafer, M. M.; Schauer, J. J.; Park, J.

2001-12-01

Recent sampling and analytical developments advanced by the project team enable the detailed elemental and isotopic fingerprinting of extremely small masses of atmospheric aerosols. Historically, this type of characterization was rarely achieved due to limitations in analytical sensitivity and a lack of awareness concerning the potential for contamination. However, with the introduction of 3rd and 4th generation ICP-MS instrumentation and the application of state-of-the- art "clean-techniques", quantitative analysis of over 40 elements in sub-milligram samples can be realized. When coupled with an efficient and validated solubilization method, ICP-MS approaches provide distinct advantages in comparison with traditional methods; greatly enhanced detection limits, improved accuracy, and isotope resolution capability, to name a few. Importantly, the ICP-MS approach can readily be integrated with techniques which enable phase differentiation and chemical speciation information to be acquired. For example, selective chemical leaching can provide data on the association of metals with major phase-components, and oxidation state of certain metals. Critical information on metal-ligand stability can be obtained when electrochemical techniques, such as adsorptive cathodic stripping voltammetry (ACSV), are applied to these same extracts. Our research group is applying these techniques in a broad range of research projects to better understand the sources and distribution of trace metals in particulate matter in the atmosphere. Using examples from our research, including recent Pb and Sr isotope ratio work on Asian aerosols, we will illustrate the capabilities and applications of these new methods.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nedrich, Sara M.; Chappaz, Anthony; Hudson, Michelle L.

Effects of hydrologic variability on reservoir biogeochemistry are relatively unknown, particularly for less studied metals like vanadium (V). Further, few studies have investigated the fate and effects of sediment-associated V to aquatic organisms in hydrologically variable systems. Our primary objective was to assess effects of hydrologic manipulation on speciation and toxicity of V (range: 635 to 1620 mg kg- 1) and other metals to Hyalella azteca and Daphnia magna. Sediments were collected from a reservoir located in a former mining area and microcosm experiments were conducted to emulate 7-day drying and inundation periods. Despite high sediment concentrations, V bioavailability remainedmore » low with no significant effects to organism survival, growth, or reproduction. The lack of V toxicity was attributed to reduced speciation (III, IV), non-labile complexation, and sorption to Al/Fe/Mn-oxyhydroxides. Zinc (Zn) increased in surface and porewater with inundation, for some sediments exceeding the U.S. EPA threshold for chronic toxicity. While no effects of Zn to organism survival or growth were observed, Zn body concentrations were negatively correlated with H. azteca growth. Results from this study indicate that V bioavailability and environmental risk is dependent on V-speciation, and V is less influenced by hydrologic variability than more labile metals such as Zn.« less

Pilot scale study on the ex situ electrokinetic removal of heavy metals from municipal wastewater sludges.

PubMed

Kim, Soon-Oh; Moon, Seung-Hyeon; Kim, Kyoung-Woong; Yun, Seong-Taek

2002-11-01

In order to remove toxic heavy metals from municipal wastewater sludges, the ex situ electrokinetic technique was studied at pilot scale. This study focused on the feasibility of the electrokinetic removal of heavy metals from sludge and the effectiveness of this technique on the variations of abiotic (physicochemical) and biotic (intracellular and extracellular) speciations of heavy metals using several analytical methods. Even though the sludge used was taken from a municipal wastewater treatment plant, the sludge contained relatively high concentrations of target metal contaminants (Cd = 6.8 mg/kg, Cr = 115.6 mg/kg, Cu = 338.7 mg/kg, and Pb = 62.8 mg/kg). The removal efficiencies of heavy metals were significantly dependent on their speciations in the sludge matrices. The electrokinetic removal efficiencies of abiotic heavy metals exceeded 70% for the mobile and weakly bound fractions, such as, the exchangeable and carbonate fractions and were lower than 35% for the strongly bound fractions, such as, the organic/sulfide and residual fractions. In the case of the biotic heavy metals, the removal efficiencies of the extracellular fractions were slightly higher than those of the intracellular fractions.

Influence of organic matter on trace metal flux in coastal sediments. [Sequim Bay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmidt, R.L.; Gibson, C.I.

1978-05-15

These studies indicate that organic matter in coastal sediment constitutes a primary sink for trace metals, both at natural and amended levels. Organic substances are also involved in controlling the mobility and flux of trace metals from sediments. Further, organically-bound trace metals in sediments appear to be an important source to deposit-feeding organisms.

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

PubMed

van den Berg, G A; Meijers, G G; van der Heijdt, L M; Zwolsman, J J

2001-06-01

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.

THE ADVANTAGE OF ILLINOIS COAL FOR FGD REMOVAL OF MERCURY

EPA Science Inventory

The paper gives results of an investigation conducted to characterize and modify mercury (Hg) speciation in Illinois coal combustion flue gas so that a Hg control strategy can be implemented in conventional flue gas desulfurization (FGD) units. Hg, in trace concentration in coal,...

Correlation between some selected trace metal concentrations in six species of fish from the Arabian Sea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashraf, M.; Jaffar, M.

1988-07-01

The role of trace metals in marine ecosystems has been keenly investigated during recent years. It is known that abundance of essential trace metals regulates the metal content in the organisms by homeostatic control mechanisms, which when cease to function cause essential trace metals to act in an either acutely or chronically toxic manner. Therefore, a correlation study based on essential and non-essential trace metal concentrations is imperative for extending the existing knowledge of bioaccumulation of trace metals in marine organisms. An attempt has been made in the present investigation to bring out quantitative correlations between the concentrations of iron,more » copper, lead and zinc in the edible muscle tissue of six species of marine fish: Salmon (salmon sole); tuna (thunnus thynnus); pomfret silver (pampus argenteus); Pomfret black (formioniger); long tail tuna (thynnus tonggel) and Indian oil sardine (sardinella longiceps). These fish are abundantly available in Pakistan along the coastal line of the Arabian Sea and have great commercial value. The computational analysis on the trace metal correlation was conducted using an MSTAT statistical package.« less

Interactions of trace metals with hydrogels and filter membranes used in DET and DGT techniques.

PubMed

Garmo, Oyvind A; Davison, William; Zhang, Hao

2008-08-01

Equilibrium partitioning of trace metals between bulk solution and hydrogels/filter was studied. Under some conditions, trace metal concentrations were higher in the hydrogels or filter membranes compared to bulk solution (enrichment). In synthetic soft water, enrichment of cationic trace metals in polyacrylamide hydrogels decreased with increasing trace metal concentration. Enrichment was little affected by Ca and Mg in the concentration range typically encountered in natural freshwaters, indicating high affinity but low capacity binding of trace metals to solid structure in polyacrylamide gels. The apparent binding strength decreased in the sequence: Cu > Pb > Ni approximately to Cd approximately to Co and a low concentration of cationic Cu eliminated enrichment of weakly binding trace metal cations. The polyacrylamide gels also had an affinity for fulvic acid and/or its trace metal complexes. Enrichment of cationic Cd in agarose gel and hydrophilic polyethersulfone filter was independent of concentration (10 nM to 5 microM) but decreased with increasing Ca/ Mg concentration and ionic strength, suggesting that it is mainly due to electrostatic interactions. However, Cu and Pb were enriched even after equilibration in seawater, indicating that these metals additionally bind to sites within the agarose gel and filter. Compared to the polyacrylamide gels, agarose gel had a lower affinity for metal-fulvic complexes. Potential biases in measurements made with the diffusive equilibration in thin-films (DET) technique, identified by this work, are discussed.

Chemical behavior of Cu, Zn, Cd, and Pb in a eutrophic reservoir: speciation and complexation capacity.

PubMed

Tonietto, Alessandra Emanuele; Lombardi, Ana Teresa; Choueri, Rodrigo Brasil; Vieira, Armando Augusto Henriques

2015-10-01

This research aimed at evaluating cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) speciation in water samples as well as determining water quality parameters (alkalinity, chlorophyll a, chloride, conductivity, dissolved organic carbon, dissolved oxygen, inorganic carbon, nitrate, pH, total suspended solids, and water temperature) in a eutrophic reservoir. This was performed through calculation of free metal ions using the chemical equilibrium software MINEQL+ 4.61, determination of labile, dissolved, and total metal concentrations via differential pulse anodic stripping voltammetry, and determination of complexed metal by the difference between the total concentration of dissolved and labile metal. Additionally, ligand complexation capacities (CC), such as the strength of the association of metals-ligands (logK'ML) and ligand concentrations (C L) were calculated via Ruzic's linearization method. Water samples were taken in winter and summer, and the results showed that for total and dissolved metals, Zn > Cu > Pb > Cd concentration. In general, higher concentrations of Cu and Zn remained complexed with the dissolved fraction, while Pb was mostly complexed with particulate materials. Chemical equilibrium modeling (MINEQL+) showed that Zn(2+) and Cd(2+) dominated the labile species, while Cu and Pb were complexed with carbonates. Zinc was a unique metal for which a direct relation between dissolved species with labile and complexed forms was obtained. The CC for ligands indicated a higher C L for Cu, followed by Pb, Zn, and Cd in decreasing amounts. Nevertheless, the strength of the association of all metals and their respective ligands was similar. Factor analysis with principal component analysis as the extraction procedure confirmed seasonal effects on water quality parameters and metal speciation. Total, dissolved, and complexed Cu and total, dissolved, complexed, and labile Pb species were all higher in winter, whereas in summer, Zn was mostly present in the complexed form. A high degree of deterioration of the reservoir was confirmed by the results of this study.

Integrated Computational and Experimental Protocol for Understanding Rh(III) Speciation in Hydrochloric and Nitric Acid Solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samuels, Alex C.; Boele, Cherilynn A.; Bennett, Kevin T.

2014-12-01

A combined experimental and theoretical approach has investigated the complex speciation of Rh(III) in hydrochloric and nitric acid media, as a function of acid concentration. This has relevance to the separation and isolation of Rh(III) from dissolved spent nuclear fuel, which is an emergent and attractive alternative source of platinum group metals, relative to traditional mining efforts.

Chromium(III)-imprinted silica gel for speciation analysis of chromium in environmental water samples with ICP-MS detection.

PubMed

Zhang, Nan; Suleiman, Jibrin Sabo; He, Man; Hu, Bin

2008-04-15

A new chromium(III)-imprinted 3-(2-aminoethylamino) propyltrimethoxysilane (AAPTS)-functionalized silica gel sorbent was synthesized by a surface imprinting technique and was employed as a selective solid-phase extraction material for speciation analysis of chromium in environmental water samples prior to its determination by inductively coupled plasma mass spectrometry (ICP-MS). The prepared Cr(III)-imprinted silica gel shows the selectivity coefficient of more than 700 for Cr(III) in the presence of Mn(II). The static adsorption capacity of the ion-imprinted and non-imprinted sorbent for Cr(III) were 30.5 mg g(-1) and 13.4 mg g(-1). It was also found that Cr(VI) could be adsorbed at low pH by the prepared imprinted silica gel, and this finding makes it feasible to enrich and determine Cr(VI) at low pH without adding reducing reagents. The imprinted silica gel sorbent offered a fast kinetics for the adsorption and desorption of both chromium species. Under the optimized conditions, the detection limits of 4.43 pg mL(-1) and 8.30 pg mL(-1) with the relative standard deviations (R.S.D.s) of 4.44% and 4.41% (C=0.5 ng mL(-1), n=7) for Cr(III) and Cr(VI) were obtained, respectively. The proposed method was successfully applied to the speciation of trace chromium in environmental water samples. To validate the proposed method, two certified reference materials were analyzed and the determined values were in a good agreement with the certified values. The developed method is rapid, selective, sensitive and applicable for the speciation of trace chromium in environmental water samples.

Extraction of trace metals from fly ash

DOEpatents

Blander, M.; Wai, C.M.; Nagy, Z.

1983-08-15

A process is described for recovering silver, gallium and/or other trace metals from a fine grained industrial fly ash associated with a process for producing phosphorous. The fly ash has a silicate base and contains surface deposits of the trace metals as oxides, chlorides or the like. The process is carried out by contacting the fly ash with AlCl/sub 3/ in an alkali halide melt to react the trace metals with the AlCl/sub 3/ to form compositions soluble in the melt and a residue containing the silicate and aluminum oxide or other aluminum precipitate, and separating the desired trace metal or metals from the melt by electrolysis or other separation techniques.

Extraction of trace metals from fly ash

DOEpatents

Blander, Milton; Wai, Chien M.; Nagy, Zoltan

1984-01-01

A process for recovering silver, gallium and/or other trace metals from a fine grained industrial fly ash associated with a process for producing phosphorous, the fly ash having a silicate base and containing surface deposits of the trace metals as oxides, chlorides or the like, with the process being carried out by contacting the fly ash with AlCl.sub.3 in an alkali halide melt to react the trace metals with the AlCl.sub.3 to form compositions soluble in the melt and a residue containing the silicate and aluminum oxide or other aluminum precipitate, and separating the desired trace metal or metals from the melt by electrolysis or other separation techniques.

Anaerobic Digestion Alters Copper and Zinc Speciation.

PubMed

Legros, Samuel; Levard, Clément; Marcato-Romain, Claire-Emmanuelle; Guiresse, Maritxu; Doelsch, Emmanuel

2017-09-19

Anaerobic digestion is a widely used organic waste treatment process. However, little is known on how it could alter the speciation of contaminants in organic waste. This study was focused on determining the influence of anaerobic digestion on the speciation of copper and zinc, two metals that generally occur at high concentration in organic waste. Copper and zinc speciation was investigated by X-ray absorption spectroscopy in four different raw organic wastes (predigestion) and their digested counterparts (postdigestion, i.e., digestates). The results highlighted an increase in the digestates of the proportion of amorphous or nanostructured copper sulfides as well as amorphous or nanostructured zinc sulfides and zinc phosphate as compared to raw waste. We therefore suggest that the environmental fate of these elements would be different when spreading either digestates or raw waste on cropland.

Trace metal contamination in surface sediments of intertidal zone from Qinhuangdao, China, revealed by geochemical and magnetic approaches: Distribution, sources, and health risk assessment.

PubMed

Zhu, Zongmin; Xue, Junhui; Deng, Yuzhen; Chen, Lin; Liu, Jiangfeng

2016-04-15

Based on geochemical and magnetic approaches, the distribution, sources, and health risk of trace metals in surface sediments from a seashore tourist city were investigated. A significant correlation was found between magnetic susceptibility (χ) and trace metals, which suggested that levels of trace metals in the sediments can be effectively depicted by the magnetic approach. The spatial distribution of χ and trace metals matched well with the city layout with relatively higher values being found in the port and busy tourist areas. This result, together with enrichment factors (EFs) and Tomlinson pollution load index (PLI) of metals, suggested that the influence of human activities on the coastal environment was noticeable. Principal component analysis (PCA) indicated that trace metals in the sediments were derived from both anthropogenic and natural sources. Noncarcinogenic risk assessment showed that there was no potential health risk of exposure to metals by means of ingestion or inhalation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Speciation Analysis of Trace Mercury in Sea Cucumber Species of Apostichopus japonicus Using High-Performance Liquid Chromatography Conjunction With Inductively Coupled Plasma Mass Spectrometry.

PubMed

Liu, Hao; Luo, Jiaoyang; Ding, Tong; Gu, Shanyong; Yang, Shihai; Yang, Meihua

2018-03-25

In this paper, a simple and cost-effective method using high-performance liquid chromatography in conjunction with inductively coupled plasma mass spectrometry with a rapid ultrasound-assisted extraction was used for analysis speciation of trace mercury in sea cucumber species of Apostichopus japonicus. The effective separation of inorganic mercury, methylmercury, and ethylmercury was achieved within 10 min using Agilent ZORBAX SB-C 18 analytical and guard columns with an isocratic mobile phase consisting of 8% methanol and 92% H 2 O containing 0.12% L-cysteine (m/v) and 0.01 mol/L ammonium acetate. Mercury species were extracted from A. japonicus samples using a solution containing 2-mercaptoethanol, L-cysteine, and hydrochloric acid and sonicating for 0.5 h. The limits of detection of inorganic mercury, methylmercury, and ethylmercury were 0.12, 0.08, and 0.20 μg/L, and the minimum detectable concentrations (measured at 0.500 g sample volume in 10.00 mL) were 2.4, 1.6, and 4.0 μg/kg, respectively. Analysis of a scallop certified reference material (GBW 10024) revealed accordance between the experimental and certified values. This study provides a reference for the evaluation of mercury speciation in sea cucumber and other seafood.

New Insight in Copper-Ion Binding to Human Islet Amyloid: The Contribution of Metal-Complex Speciation To Reveal the Polypeptide Toxicity.

PubMed

Magrì, Antonio; La Mendola, Diego; Nicoletti, Vincenzo Giuseppe; Pappalardo, Giuseppe; Rizzarelli, Enrico

2016-09-05

Type-2 diabetes (T2D) is considered to be a potential threat on a global level. Recently, T2D has been listed as a misfolding disease, such as Alzheimer's and Parkinson's diseases. Human islet amyloid polypeptide (hIAPP) is a molecule cosecreted in pancreatic β cells and represents the main constituent of an aggregated amyloid found in individuals affected by T2D. The trace-element serum level is significantly influenced during the development of diabetes. In particular, the dys-homeostasis of Cu(2+) ions may adversely affect the course of the disease. Conflicting results have been reported on the protective role played by complex species formed by Cu(2+) ions with hIAPP or its peptide fragments in vitro. The histidine (His) residue at position 18 represents the main binding site for the metal ion, but contrasting results have been reported on other residues involved in metal-ion coordination, in particular those toward the N or C terminus. Sequences that encompass regions 17-29 and 14-22 were used to discriminate between the two models of the hIAPP coordination mode. Due to poor solubility in water, poly(ethylene glycol) (PEG) derivatives were synthesized. A peptide fragment that encompasses the 17-29 region of rat amylin (rIAPP) in which the arginine residue at position 18 was substituted by a histidine residue was also obtained to assess that the PEG moiety does not alter the peptide secondary structure. The complex species formed by Cu(2+) ions with Ac-PEG-hIAPP(17-29)-NH2 , Ac-rIAPP(17-29)R18H-NH2 , and Ac-PEG-hIAPP(14-22)-NH2 were studied by using potentiometric titrations coupled with spectroscopic methods (UV/Vis, circular dichroism, and EPR). The combined thermodynamic and spectroscopic approach allowed us to demonstrate that hIAPP is able to bind Cu(2+) ions starting from the His18 imidazole nitrogen atom toward the N-terminus domain. The stability constants of copper(II) complexes with Ac-PEG-hIAPP(14-22)-NH2 were used to simulate the different experimental conditions under which aggregate formation and oxidative stress of hIAPP has been reported. Speciation unveils: 1) the protective role played by increased amounts of Cu(2+) ions on the hIAPP fibrillary aggregation, 2) the effect of adventitious trace amounts of Cu(2+) ions present in phosphate-buffered saline (PBS), and 3) a reducing fluorogenic probe on H2 O2 production attributed to the polypeptide alone. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Assessing the concentration, speciation, and toxicity of dissolved metals during mixing of acid-mine drainage and ambient river water downstream of the Elizabeth Copper Mine, Vermont, USA

USGS Publications Warehouse

Balistrieri, L.S.; Seal, R.R.; Piatak, N.M.; Paul, B.

2007-01-01

The authors determine the composition of a river that is impacted by acid-mine drainage, evaluate dominant physical and geochemical processes controlling the composition, and assess dissolved metal speciation and toxicity using a combination of laboratory, field and modeling studies. Values of pH increase from 3.3 to 7.6 and the sum of dissolved base metal (Cd + Co + Cu + Ni + Pb + Zn) concentrations decreases from 6270 to 100 ??g/L in the dynamic mixing and reaction zone that is downstream of the river's confluence with acid-mine drainage. Mixing diagrams and PHREEQC calculations indicate that mixing and dilution affect the concentrations of all dissolved elements in the reach, and are the dominant processes controlling dissolved Ca, K, Li, Mn and SO4 concentrations. Additionally, dissolved Al and Fe concentrations decrease due to mineral precipitation (gibbsite, schwertmannite and ferrihydrite), whereas dissolved concentrations of Cd, Co, Cu, Ni, Pb and Zn decrease due to adsorption onto newly formed Fe precipitates. The uptake of dissolved metals by aquatic organisms is dependent on the aqueous speciation of the metals and kinetics of complexation reactions between metals, ligands and solid surfaces. Dissolved speciation of Cd, Cu, Ni and Zn in the mixing and reaction zone is assessed using the diffusive gradients in thin films (DGT) technique and results of speciation calculations using the Biotic Ligand Model (BLM). Data from open and restricted pore DGT units indicate that almost all dissolved metal species are inorganic and that aqueous labile or DGT available metal concentrations are generally equal to total dissolved concentrations in the mixing zone. Exceptions occur when labile metal concentrations are underestimated due to competition between H+ and metal ions for Chelex-100 binding sites in the DGT units at low pH values. Calculations using the BLM indicate that dissolved Cd and Zn species in the mixing and reaction zone are predominantly inorganic, which is consistent with the DGT results. Although the DGT method indicates that the majority of aqueous Cu species are inorganic, BLM calculations indicate that dissolved Cu is inorganic at pH 5.5. Integrated dissolved labile concentrations of Cd, Cu and Zn in the mixing and reaction zone are compared to calculated acute toxicity concentrations (LC50 values) for fathead minnows (Pimephales promelas) (Cd, Cu and Zn) and water fleas (Ceriodaphnia dubia) (Cd and Cu) using the BLM, and to national recommended water quality criteria [i.e., criteria maximum concentration (CMC) and criterion continuous concentration (CCC)]. Observed labile concentrations of Cd and Zn are below LC50 values and CMC for Cd, but above CCC and CMC for Zn at sites <30 m downstream of the confluence. In contrast, labile Cu concentrations exceed LC50 values for the organisms as well as CCC and CMC at sites <30 m downstream of the confluence. These results suggest that environmental conditions at sites closest to the confluence of the river and acid-mine drainage should not support healthy aquatic organisms. ?? 2007 Elsevier Ltd. All rights reserved.

Trace metal levels, sources, and ecological risk assessment in a densely agricultural area from Saudi Arabia.

PubMed

Al-Wabel, Mohammad I; Sallam, Abd El-Azeem S; Usman, Adel R A; Ahmad, Mahtab; El-Naggar, Ahmed Hamdy; El-Saeid, Mohammed Hamza; Al-Faraj, Abdulelah; El-Enazi, Khaled; Al-Romian, Fahad A

2017-06-01

The present study was conducted in one of the most densely cultivated area of Al-Qassim region in Kingdom of Saudi Arabia to (i) monitor trace metal (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) contents in surface and subsurface soils, (ii) assess the pollution and potential ecological risk levels of trace metals, and (iii) identify trace metal sources using enrichment factor (EF), correlation matrix, and principal component analysis (PCA). The pollution levels of the analyzed trace metals calculated by the geoaccumulation index (I geo ) and contamination factor (C f ) suggested that the soils were highly contaminated with Cd and moderately contaminated with Pb. Based on the average values of EF, soil samples were found to present extremely high enrichment for Cd, significant enrichment for Pb, moderate enrichment for Zn, and deficient to minimal enrichment for other trace metals. Among the analyzed trace metals, a very high ecological risk was observed only in the case of Cd at some sampling sites. Meanwhile, other investigated trace metals had a low ecological risk. The results of PCA combined with correlation matrix suggested that Fe, Mn, Zn, Cu, Cr Ni, Cu, and Co represent natural abundance in soil, but Cd, Pb, and Cu are of anthropogenic inputs, mainly due to agrochemical and fertilizer applications. It could be generally concluded that the obtained results can be useful for assessing and conducting a future program for trace metal monitoring in agricultural areas of Saudi Arabia.

Comparative characterization of sewage sludge compost and soil: Heavy metal leaching characteristics.

PubMed

Fang, Wen; Wei, Yonghong; Liu, Jianguo

2016-06-05

The leaching and accumulation of heavy metals are major concerns following the land application of sewage sludge compost (SSC). We comparatively characterized SSC, the reference soil, and the SSC amended soil to investigate their similarities and differences regarding heavy metal leaching behavior and then to evaluate the effect of SSC land application on the leaching behavior of soil. Results showed that organic matter, including both of particulate organic matter (POM) and dissolved organic matter (DOM), were critical factors influencing heavy metal leaching from both of SSC and the soil. When SSC was applied to soil at the application rate of 48t/ha, the increase of DOM content slightly enhanced heavy metal leaching from the amended soil over the applicable pH domain (6

In-Situ Analysis Of Metal(loid)s In Plants: State Of The Art And Artefacts

EPA Science Inventory

Metals and metalloids play important roles in plant function and metabolism. Likewise, plants subsequently introduce vital dietary nutrition to people and animals. Understanding the transport, localisation and speciation of these elements is critical for understanding availabil...

Chromium fractionation and speciation in natural waters.

PubMed

Pereira, Catarinie Diniz; Techy, João Gabriel; Ganzarolli, Edgard Moreira; Quináia, Sueli Pércio

2012-05-01

It is common for leather industries to dump chromium-contaminated effluent into rivers and other bodies of water. Thus, it is crucial to know the impacts caused by this practice to the environment. A study on chromium partitioning and speciation, with determination at trace levels, was carried out in a potentially contaminated creek. Chromium fractionation and speciation was performed using a flow-injection preconcentration system and detection by flame atomic absorption spectrometry. High levels of this element were found in the particulate material (449-9320 mg kg(-1)), which indicates its compatibility with this fraction. The concentration of Cr(iii) in the water samples collected ranged from 5.2-105.2 μg L(-1). Cr(vi) was always below of the DL (0.3 μg L(-1)). Chromium accumulation observed in the sediment (873-1691 mg kg(-1)) may confirm contamination due to the long term release of contaminated effluents in the creek.

Investigation of the Matrix Effect on the Accuracy of Quantitative Analysis of Trace Metals in Liquids Using Laser-Induced Breakdown Spectroscopy with Solid Substrates.

PubMed

Xiu, Junshan; Dong, Lili; Qin, Hua; Liu, Yunyan; Yu, Jin

2016-12-01

The detection limit of trace metals in liquids has been improved greatly by laser-induced breakdown spectroscopy (LIBS) using solid substrate. A paper substrate and a metallic substrate were used as a solid substrate for the detection of trace metals in aqueous solutions and viscous liquids (lubricating oils) respectively. The matrix effect on quantitative analysis of trace metals in two types of liquids was investigated. For trace metals in aqueous solutions using paper substrate, the calibration curves established for pure solutions and mixed solutions samples presented large variation on both the slope and the intercept for the Cu, Cd, and Cr. The matrix effects among the different elements in mixed solutions were observed. However, good agreement was obtained between the measured and known values in real wastewater. For trace metals in lubricating oils, the matrix effect between the different oils is relatively small and reasonably negligible under the conditions of our experiment. A universal calibration curve can be established for trace metals in different types of oils. The two approaches are verified that it is possible to develop a feasible and sensitive method with accuracy results for rapid detection of trace metals in industrial wastewater and viscous liquids by laser-induced breakdown spectroscopy. © The Author(s) 2016.

Determining the Chemical and Biological Availability of Zinc in Urban Stormwater Retention Ponds

NASA Astrophysics Data System (ADS)

Camponelli, K.; Casey, R.; Lev, S. M.; Landa, E. R.; Snodgrass, J.

2005-12-01

Highway runoff has the potential to negatively impact receiving systems due to transport of contaminants that accumulate on road surfaces. Metals such as copper and zinc are major components of automobile brake pads and tires, respectively. As these automobile parts are degraded, these metal containing particulates are deposited on the roadway and are washed into storm water retention ponds and surface water bodies during precipitation events. It has been estimated that 15 to 60% of the Zn in urban stormwater runoff comes from tire wear and that tire wear is a significant source of Zn to the environment with release inventories comparable to waste incineration sources. In urban and sub-urban systems, this large source of Zn can accumulate in stormwater retention ponds which serve as habitat for a variety of species. Understanding the chemical and biological availability of Zn to biota is integral to assessing the habitat quality of retention ponds. This study is a first effort to relate the amount and speciation of Zn in a retention pond to Zn inputs through highway-derived runoff events. In addition, results suggest that the chemical speciation and availability of particulate Zn can be related to the bioavailability and toxicity of Zn to pond organisms (i.e. larval amphibians). The study site in Owings Mills, MD is located next to a four-lane highway from which it receives runoff through a single culvert. Five species of anurans are known to utilize the pond as a breeding site and Zn in amphibian tissues and retention pond sediments were highly elevated at this site in 2001 and 2002. A recent analysis of pond sediments, soils, roadway dust and storm water collected at this site suggests that roadway particulate matter transported during runoff events is the dominant source of Zn in this system. Overall, Zn and other trace metals were found to be most abundant in the clay sized faction of pond sediments and soils. The pond cores were found to have higher Zn and Cu concentrations at both the surface and a deeper interval possibly related to a change in land use during the pond's history. Pond sediments are above natural soil background for both Zn and Cu and represent mixing between the roadway particulates and local soils. It is therefore likely that these particulates are the primary source of metals to the pond.

The heavy metal partition in size-fractions of the fine particles in agricultural soils contaminated by waste water and smelter dust.

PubMed

Zhang, Haibo; Luo, Yongming; Makino, Tomoyuki; Wu, Longhua; Nanzyo, Masami

2013-03-15

The partitioning of pollutant in the size-fractions of fine particles is particularly important to its migration and bioavailability in soil environment. However, the impact of pollution sources on the partitioning was seldom addressed in the previous studies. In this study, the method of continuous flow ultra-centrifugation was developed to separate three size fractions (<1 μm, <0.6 μm and <0.2 μm) of the submicron particles from the soil polluted by wastewater and smelter dust respectively. The mineralogy and physicochemical properties of each size-fraction were characterized by X-ray diffraction, transmission electron microscope etc. Total content of the polluted metals and their chemical speciation were measured. A higher enrichment factor of the metals in the fractions of <1 μm or less were observed in the soil contaminated by wastewater than by smelter dust. The organic substance in the wastewater and calcite from lime application were assumed to play an important role in the metal accumulation in the fine particles of the wastewater polluted soil. While the metal accumulation in the fine particles of the smelter dust polluted soil is mainly associated with Mn oxides. Cadmium speciation in both soils is dominated by dilute acid soluble form and lead speciation in the smelter dust polluted soil is dominated by reducible form in all particles. This implied that the polluted soils might be a high risk to human health and ecosystem due to the high bioaccessibility of the metals as well as the mobility of the fine particles in soil. Copyright © 2013 Elsevier B.V. All rights reserved.

Sorption, desorption, and speciation of Cd, Ni, and Fe by four calcareous soils as affected by pH.

PubMed

Tahervand, Samaneh; Jalali, Mohsen

2016-06-01

The sorption, desorption, and speciation of cadmium (Cd), nickel (Ni), and iron (Fe) in four calcareous soils were investigated at the pH range of 2-9. The results indicated that sorption of Fe by four soils was higher than 80 % at pH 2, while in the case of Cd and Ni was less than 30 %. The most common sequence of metal sorption at pH 2-9 for four soils was in the order of Fe ≫ Ni > Cd. Cadmium and Ni sorption as a function of pH showed the predictable trend of increasing metal sorption with increase in equilibrium pH, while the Fe sorption trend was different and characterized by three phases. With regard to the order of Cd, Ni, and Fe sorption on soils, Cd and Ni showed high affinity for organic matter (OM), whereas Fe had high tendency for calcium carbonate (CaCO3). Results of metal desorption using 0.01 M NaCl demonstrated that metal sorption on soils containing high amounts of CaCO3 was less reversible in comparison to soils containing high OM. In general, Cd and Ni desorption curves were characterized by three phases; (1) the greatest desorption at pH 2, (2) the low desorption at pH 3-7, and (3) the least desorption at pH > 7. The MINTEQ speciation solubility program showed that the percentage of free metals declined markedly with increase of pH, while the percentage of carbonate and hydroxyl species increased. Furthermore, MINTEQ predicted that saturation index (SI) of metals increased with increasing pH.

Sulfur, sulfides, oxides and organic matter aggregated in submarine hydrothermal plumes at 9°50‧N East Pacific Rise

NASA Astrophysics Data System (ADS)

Breier, J. A.; Toner, B. M.; Fakra, S. C.; Marcus, M. A.; White, S. N.; Thurnherr, A. M.; German, C. R.

2012-07-01

Deep-sea hydrothermal plume particles are known to sequester seawater trace elements and influence ocean-scale biogeochemical budgets. The relative importance of biotic versus abiotic oxidation-reduction and other particle-forming reaction, however, and the mechanisms of seawater trace element sequestration remain unknown. Suspended particulate material was collected from a non-buoyant hydrothermal plume by in situ filtration at 9°50‧N East Pacific Rise during a 3-day, 24 sample, time-series. Twenty-three samples were digested for total elemental analysis. One representative sample was selected for particle-by-particle geochemical analyses including elemental composition by X-ray fluorescence, speciation of Fe, S, and C by 1s X-ray absorption near edge structure spectroscopy, and X-ray diffraction. Consistent with past studies, positive linear correlations were observed for P, V, As, and Cr with Fe in the bulk chemistry. Arsenic was associated with both Fe oxyhydroxides and sulfides but not uniformly distributed among either mineral type. Particle aggregation was common. Aggregates were composed of minerals embedded in an organic matrix; the minerals ranged from <20 nm to >10 μm in diameter. The speciation of major mineral forming elements (Fe, Mn, S) was complex. Over 20 different minerals were observed, nine of which were either unpredicted by thermodynamic modeling or had no close match in the thermodynamic database. Sulfur-bearing phases consisted of polysulfides (S6, S8), and metal sulfides (Fe, Cu, Zn, Mn). Four dominant species, Fe oxyhydroxide, Fe monosulfide, pyrrhotite, and pyrite, accounted for >80% of the Fe present. Particulate Mn was prevalent in both oxidized and reduced minerals. The organic matrix was: (1) always associated with minerals, (2) composed of biomolecules, and (3) rich in S. Possible sources of this S-rich organic matter include entrained near vent biomass and in situ production by S-oxidizing microorganisms. These results indicate that particle aggregation with organic material is prevalent in dispersing hydrothermal plume fluxes, as well as in sinking particulate matter at this site. Particle aggregation and organic coatings can influence the reactivity, transport, and residence time of hydrothermal particles in the water column. Thus a biogeochemical approach is critical to understanding the net effect of hydrothermal fluxes on ocean and sedimentary trace element budgets.

Selenium, Vanadium, and Chromium as Micronutrients to Improve Metabolic Syndrome.

PubMed

Panchal, Sunil K; Wanyonyi, Stephen; Brown, Lindsay

2017-03-01

Trace metals play an important role in the proper functioning of carbohydrate and lipid metabolism. Some of the trace metals are thus essential for maintaining homeostasis, while deficiency of these trace metals can cause disorders with metabolic and physiological imbalances. This article concentrates on three trace metals (selenium, vanadium, and chromium) that may play crucial roles in controlling blood glucose concentrations possibly through their insulin-mimetic effects. For these trace metals, the level of evidence available for their health effects as supplements is weak. Thus, their potential is not fully exploited for the target of metabolic syndrome, a constellation that increases the risk for cardiovascular disease and type 2 diabetes. Given that the prevalence of metabolic syndrome is increasing throughout the world, a simpler option of interventions with food supplemented with well-studied trace metals could serve as an answer to this problem. The oxidation state and coordination chemistry play crucial roles in defining the responses to these trace metals, so further research is warranted to understand fully their metabolic and cardiovascular effects in human metabolic syndrome.

The effects of the biogeochemical properties of clay minerals on the Pb sorption and desorption in various redox condition

NASA Astrophysics Data System (ADS)

Koo, T. H.; Kim, J. Y.; Kim, J. W.

2016-12-01

The fate and transportation of hazardous trace metal in soil environment can be controlled by various factors including temperature, geological location, properties of bed rock or sediment, human behavior, and biogeochemical reactions. The sorption and desorption process is one of the major process for control the transportation of trace metal in soil-water system. Nonetheless, few studies were focused on the biological controlling parameters, particularly redox reaction of structural metal of clay minerals. Thus, the objective of the present study is to investigate the correlation between the sorption and desorption reaction of Pb and biogeochemical properties of clay minerals. The effects of redox state of structural Fe and layer charge of the minerals on the migration/speciation of Pb at the various geochemical environment will be elucidated. The Fe-rich smectite, nontronite (NAu-1), and bulk soil samples which were collected from abandoned mine areas were reduced by microbial respiration by Shewanella Oneidensis MR-1 and/or Na-dithionite to various oxidation state of structural Fe. Then the Pb-stock solution made with common lead and nitric acid were spiked into the mineral/soil slurry with various Pb concentration to test the sorption and desorption reaction upto 7 days. The reaction was stopped at each time point by freezing the pellet and supernatant separately after centrifugation. Then the concentration and stable isotope ratio of Pb in the supernatant were measured using Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and Multicollector (MC)-ICP-MS. The structural as well as chemical modification on nontronite and bulk soil sample were measured using x-ray diffraction (XRD), scanning electron microscopy (SEM) and wet chemistry analysis. The changes in Pb species in supernatant by sorption and desorption and its consequences on the clay structural/biogeochemical properties will be discussed.

Reconstructing Early Industrial Contributions to Legacy Trace Metal Contamination in Southwestern Pennsylvania.

PubMed

Rossi, Robert J; Bain, Daniel J; Hillman, Aubrey L; Pompeani, David P; Finkenbinder, Matthew S; Abbott, Mark B

2017-04-18

Early industrial trace metal loadings are poorly characterized but potentially substantial sources of trace metals to the landscape. The magnitude of legacy contamination in southwestern Pennsylvania, the cradle of North American fossil fuel industrialization, is reconstructed from trace metal concentrations in a sediment core with proxies including major and trace metal chemistry, bulk density, and magnetic susceptibility. Trace metal chemistry in this sediment record reflects 19th and 20th century land use and industry. In particular, early 19th century arsenic loadings to the lake are elevated from pesticides used by early European settlers at a lakeside tannery. Later, sediment barium concentrations rise, likely reflecting the onset of acidic mine drainage from coal operations. Twentieth century zinc, cadmium, and lead concentrations are dominated by emissions from the nearby, infamous Donora Zinc Works yet record both the opening of a nearby coal-fired power plant and amendments to the Clean Air Act. The impact of early industry is substantial and rivals more recent metal fluxes, resulting in a significant potential source of contaminated sediments. Thus, modern assessments of trace metal contamination cannot ignore early industrial inputs, as the potential remobilization of legacy contamination would impact ecosystem and human health.

Geochemical study of stream waters affected by mining activities in the SE Spain

NASA Astrophysics Data System (ADS)

Garcia-Lorenzo, Maria Luz; Perez-Sirvent, Carmen; Martinez-Sanchez, Maria Jose; Bech, Jaime

2015-04-01

Water pollution by dissolved metals in mining areas has mainly been associated with the oxidation of sulphide-bearing minerals exposed to weathering conditions, resulting in low quality effluents of acidic pH and containing a high level of dissolved metals. According to transport process, three types of pollution could be established: a) Primary contamination, formed by residues placed close to the contamination sources; b) Secondary contamination, produced as a result of transport out of its production areas; c) Tertiary contamination. The aim of this work was to study trace element in water samples affected by mining activities and to apply the MINTEQ model for calculating aqueous geochemical equilibria. The studied area constituted an important mining centre for more than 2500 years, ceasing activity in 1991. The ore deposits of this zone have iron, lead and zinc as the main metal components. As a result, a lot of contaminations sources, formed by mining steriles, waste piles and foundry residues are present. For this study, 36 surficial water samples were collected after a rain episode in 4 different areas. In these samples, the trace element content was determined by by flame atomic absorption spectrometry (Fe and Zn), electrothermal atomization atomic absorption spectrometry (Pb and Cd), atomic fluorescence spectrometry (As) and ICP-MS for Al. MINTEQA2 is a geochemical equilibrium speciation model capable of computing equilibria among the dissolved, adsorbed, solid, and gas phases in an environmental setting and was applied to collected waters. Zone A: A5 is strongly influenced by tailing dumps and showed high trace element content. In addition, is influenced by the sea water and then showed high bromide, chloride, sodium and magnesium content, together with a basic pH. The MINTEQ model application suggested that Zn and Cd could precipitate as carbonate (hidrocincite, smithsonite and otavite). A9 also showed acid pH and high trace element content; is influenced by tailing dumps and also by waters from gully watercourses, transporting materials from Sierra Minera. The MINTEQ simulation showed that Pb and Ca could precipitate as sulphates (anglesite and gypsum). Waters affected by secondary contamination have been mixed with carbonate materials, present in the zone increasing the pH. Some elements have precipitated, such as Cu and Pb, while Cd, Zn and As are soluble. The MINTEQ model results showed that in A10 and A14, Al could precipitate as diaspore but also carbonates could be formed, particularly dolomite. These model in A12 sample showed that soluble Zn could precipitate as carbonate and Al as oxyhydroxide, similarly than in A13. A2 and A6 waters are affected by tertiary contamination and showed basic pH, soluble carbonates and lower trace element content. Only Zn, Cd and Al are present. The speciation model showed that in A2, Cd and Zn could precipitate as carbonates while Al as oxihydroxide. In A6, the model suggested that soluble Pb could precipitate as carbonate (hidrocerusite and cerusite) or as hydroxide; Al as diaspore, Ca as calcite and Fe as hematite. Zone B: All waters are strongly affected by mining activities and showed acid pH, high trace element content and high content of soluble sulphates. The MINTEQ results showed that in B8, Fe could precipitate as hydroxychloride and in B12 could form alunite. In B9, B10, B13 y B14, the model estimates the precipitation of anglesite, gypsum and Fe hydroxichloride (B9 and B10), diaspore in B13 and B14, and gypsum and Fe hydroxychloride in B13. All the sampling points collected in Zone C are affected by primary contamination, because there are a lot of tailing dumps. C1 showed high trace element content because is a reception point of a lot of tailing dumps. Water samples from C3 to C8 also had acid pH and high trace element content, particularly As, Zn and Cd. In addition, they showed high soluble sulphates. C2 water showed neutral pH, soluble carbonate and low trace element content because is influenced by a stabilised tailing dump. In all samples, except C2, the MINTEQ model showed that a lot of efflorescences could be formed, mainly sulphates. Zone D: All waters collected in this zone showed acid pH and high trace element content, mainly Zn, Cd and As. MINTEQ model results showed that elements could precipitate as jarosite but also anglesite in D8 and gypsum in D9, D11 and D12. D1 is affected by secondary contamination, which showed higher pH (still acid) and lower content in soluble salts and trace elements. The MINTEQ model suggested that Al could precipitate as diaspore, gibbsite and alunite. The applied model is an appropriate tool for the analysis of waters affected by mining activities. The obtained simulations confirm natural attenuation processes.

Metal speciation and toxicity of Tamar Estuary water to larvae of the Pacific oyster, Crassostrea gigas.

PubMed

Money, Cathryn; Braungardt, Charlotte B; Jha, Awadhesh N; Worsfold, Paul J; Achterberg, Eric P

2011-07-01

As part of the PREDICT Tamar Workshop, the toxicity of estuarine waters in the Tamar Estuary (southwest England) was assessed by integration of metal speciation determination with bioassays. High temporal resolution metal speciation analysis was undertaken in situ by deployment of a Voltammetric In situ Profiling (VIP) system. The VIP detects Cd (cadmium), Pb (lead) and Cu (copper) species smaller than 4 nm in size and this fraction is termed 'dynamic' and considered biologically available. Cadmium was mainly present in the dynamic form and constituted between 56% and 100% of the total dissolved concentration, which was determined subsequently in the laboratory in filtered discrete samples. In contrast, the dynamic Pb and Cu fractions were less important, with a much larger proportion of these metals associated with organic ligands and/or colloids (45-90% Pb and 46-85% Cu), which probably reduced the toxicological impact of these elements in this system. Static toxicity tests, based on the response of Crassostrea gigas larva exposed to discrete water samples showed a high level of toxicity (up to 100% abnormal development) at two stations in the Tamar, particularly during periods of the tidal cycle when the influence of more pristine coastal water was at its lowest. Competitive ligand-exchange Cu titrations showed that natural organic ligands reduced the free cupric ion concentration to levels that were unlikely to have been the sole cause of the observed toxicity. Nonetheless, it is probable that the combined effect of the metals determined in this work contributed significantly to the bioassay response. Copyright © 2011 Elsevier Ltd. All rights reserved.

Diurnal variations of dissolved and colloidal organic carbon and trace metals in a boreal lake during summer bloom.

PubMed

Pokrovsky, O S; Shirokova, L S

2013-02-01

This work describes variation of element concentration in surface water of a subarctic organic-rich lake during the diurnal cycle of photosynthesis. An unusually hot summer 2010 in European part of subarctic Russia produced elevated surface water temperature (28-30 °C) and caused massive cyanobacterial bloom. Diurnal variation of ~40 dissolved macro and trace elements and organic carbon were recorded in the humic Lake Svyatoe in the White Sea drainage basin. Two days continuous measurements with 3 h sampling steps at the surface (0.5 m) allowed tracing cyanobacterial activity via pH and O₂ measurement and revealed constant concentrations (within ±20-30%) of all major elements (Na, Mg, Cl, SO₄, K, Ca), organic and inorganic carbon and most trace elements (Li, B, Sc, Ti, Ni, Cu, Ga, As, Rb, Sr, Y, Zr, Mo, Sb, medium and heavy REEs, Hf, Pb, Th, U). The concentration of Mn demonstrated a factor of 3 decrease during the day following Mn adsorption onto cyanobacterial cells due to ~1 pH unit raise during the photosynthesis and Mn release during the night due to desorption from the cell surface. The role of Mn(II) photo-oxidation by reactive oxygen species could be also pronounced, although its contribution to Mn diurnal variation was much smaller than the adsorption at the cell surfaces. Similar pattern, but with much lesser variations (c.a., 10-20%), was recorded for Ba and Fe. On-site ultrafiltration technique allowed to distinguish between low molecular weight (LMW) complexes (<1 kDa) and high molecular weight (HMW) colloids (1 kDa-0.22 μm) and to assess their diurnal pattern. Colloidal Al and Fe were the highest during the night, when the contribution of HMW allochthonous colloids was maximal. Typical insoluble trivalent and tetravalent elements exhibited constant complexation (>80-90%) with HMW allochthonous organics, independent on the diel photosynthetic cycle. Finally, biologically-relevant metals (Cu, Co, Cr, V, and Ni) demonstrated significant variations of colloidal fractions (from 10 to 60%) not directly related to the photosynthesis. The majority of possible metal nutrients, being strongly associated with organic and organo-mineral colloids do not exhibit any measurable concentration variation during photosynthesis. The two types of element behavior during cyanobacterial bloom in the water column--constant concentration and sinusoidal variations--likely depend on element speciation in solution and their relative affinity to surfaces of aquatic microorganisms and complexation with authochthonous and allochthonous organic matter. Copyright © 2012 Elsevier Ltd. All rights reserved.

Speciation in Metal Toxicity and Metal-Based Therapeutics

PubMed Central

Templeton, Douglas M.

2015-01-01

Metallic elements, ions and compounds produce varying degrees of toxicity in organisms with which they come into contact. Metal speciation is critical to understanding these adverse effects; the adjectives “heavy” and “toxic” are not helpful in describing the biological properties of individual elements, but detailed chemical structures are. As a broad generalization, the metallic form of an element is inert, and the ionic salts are the species that show more significant bioavailability. Yet the salts and other chelates of a metal ion can give rise to quite different toxicities, as exemplified by a range of carcinogenic potential for various nickel species. Another important distinction comes when a metallic element is organified, increasing its lipophilicity and hence its ability to penetrate the blood brain barrier, as is seen, for example, with organic mercury and tin species. Some metallic elements, such as gold and platinum, are themselves useful therapeutic agents in some forms, while other species of the same element can be toxic, thus focusing attention on species interconversions in evaluating metal-based drugs. The therapeutic use of metal-chelating agents introduces new species of the target metal in vivo, and this can affect not only its desired detoxification, but also introduce a potential for further mechanisms of toxicity. Examples of therapeutic iron chelator species are discussed in this context, as well as the more recent aspects of development of chelation therapy for uranium exposure. PMID:29056656

Heavy metals in the volcanic environment and thyroid cancer.

PubMed

Vigneri, R; Malandrino, P; Gianì, F; Russo, M; Vigneri, P

2017-12-05

In the last two decades thyroid cancer incidence has increased worldwide more than any other cancer. Overdiagnosis of subclinical microcarcinomas has certainly contributed to this increase but many evidences indicate that a true increase, possibly due to environmental factors, has also occurred. Thyroid cancer incidence is markedly increased in volcanic areas. Thus, the volcanic environment is a good model to investigate the possible factors favoring thyroid cancer. In the volcanic area of Mt. Etna in Sicily, as well as in other volcanic areas, a non-anthropogenic pollution with heavy metals has been documented, a consequence of gas, ash and lava emission. Soil, water and atmosphere contamination, via the food chain, biocontaminate the residents as documented by high levels in the urines and the scalp hair compared to individuals living in adjacent non-volcanic areas. Trace amounts of metals are essential nutrients but, at higher concentrations, can be toxic for living cells. Metals can behave both as endocrine disruptors, perturbing the hormonal system, and as carcinogens, promoting malignant transformation. Similarly to other carcinogens, the transforming effect of heavy metals is higher in developing organisms as the fetus (contaminated via the mother) and individuals in early childhood. In the last decades environment metal pollution has greatly increased in industrialized countries. Although still within the "normal" limits for each single metal the hormesis effect (heavy metal activity at very low concentration because of biphasic, non linear cell response) and the possible potentiation effect resulting from the mixture of different metals acting synergistically can explain cell damage at very low concentrations. The effect of metals on the human thyroid is poorly studied: for some heavy metals no data are available. The scarce studies that have been performed mainly focus on metal effect as thyroid endocrine disruptors. The metal concentration in tissues has been rarely measured in the thyroid. Heavy metal accumulation and metabolism in the thyroid or the carcinogenic activity of different doses and different speciation of metals has not been investigated. These studies are now warranted to better understand thyroid biology and heavy metal role in human thyroid carcinogenesis. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Accumulation and trace-metal variability of estuarine sediments, St. Bernard delta geomorphic region, Louisiana

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landrum, K.E.

1995-10-01

Prior to government regulation, little monitoring of metal discharges into the canals, bayous, and rivers that drain estuarine systems occured. Discharges of trace-metals by industries and municipalities into surface water bodies are presently regulated through the use of Federal and State mandated permit programs. Resource management of economically important estuarine systems has fostered increasing concern over the accumulation of trace-metal pollutants in water, sediments, and biota from these dynamic areas. The acid-leachable concentrations of fourteen trace-metals were determined for 125 bottom sediment samples and 50 core interval samples by plasma emission analysis. Bottom sediments of the St. Bernard estuarom complexmore » consist predominantly of silty clays and clayey silts derived from the erosion of the St. Bernard lobe of the Mississippi River delta and sediments associated with historic crevasses along the Mississippi River. Within the 2 cm core intervals, trace-metal concentrations of Ba, Cr, Cd, Pb, and Zn increased by 10% to 18% in sediments accumulated within the last 75 years. Trace-metal concentrations from sediments for the study area tend to have greater mean concentrations than Florida estuarine sediments, basinwide and Gulf Coast trace-metal comparisons, sediment geochronology. Rates varied from 0.12 to 0.21 cm/yr. Within the 2 cm core intervals, trace-metal concentrations of Ba, Cr, Cd, Pb, and Zn increased by 10% to 18% in sediments accumulated within the last 75 years. Natural trace-metal variability was examined through the use of an aluminum normalization model based on Florida and Louisiana estuarine sediments, basinwide and Gulf Coast trace-metal comparisons, sediment geochronology, and grain-size corrected data. Elevated concentrations of As, Ba, Cd, Pb, V and Zn were noted from sediments associated with oil and gas drilling and production, sandblasting and shipbuilding, dredging, and stormwater, municipal, and industrial discharges.« less

Leaching for recovery of copper from municipal solid waste incineration fly ash: influence of ash properties and metal speciation.

PubMed

Lassesson, Henric; Fedje, Karin Karlfeldt; Steenari, Britt-Marie

2014-08-01

Recovery of metals occurring in significant amounts in municipal solid waste incineration fly ash, such as copper, could offer several advantages: a decreased amount of potentially mobile metal compounds going to landfill, saving of natural resources and a monetary value. A combination of leaching and solvent extraction may constitute a feasible recovery path for metals from municipal solid waste incineration fly ash. However, it has been shown that the initial dissolution and leaching is a limiting step in such a recovery process. The work described in this article was focused on elucidating physical and chemical differences between two ash samples with the aim of explaining the differences in copper release from these samples in two leaching methods. The results showed that the chemical speciation is an important factor affecting the release of copper. The occurrence of copper as phosphate or silicate will hinder leaching, while sulphate and chloride will facilitate leaching. © The Author(s) 2014.

Atmospheric trace metals measured at a regional background site (Welgegund) in South Africa

NASA Astrophysics Data System (ADS)

Venter, Andrew D.; van Zyl, Pieter G.; Beukes, Johan P.; Josipovic, Micky; Hendriks, Johan; Vakkari, Ville; Laakso, Lauri

2017-03-01

Atmospheric trace metals can cause a variety of health-related and environmental problems. Only a few studies on atmospheric trace metal concentrations have been conducted in South Africa. Therefore the aim of this study was to determine trace metal concentrations in aerosols collected at a regional background site, i.e. Welgegund, South Africa. PM1, PM1-2. 5 and PM2. 5-10 samples were collected for 13 months, and 31 atmospheric trace metal species were detected. Atmospheric iron (Fe) had the highest concentrations in all three size fractions, while calcium (Ca) was the second-most-abundant species. Chromium (Cr) and sodium (Na) concentrations were the third- and fourth-most-abundant species, respectively. The concentrations of the trace metal species in all three size ranges were similar, with the exception of Fe, which had higher concentrations in the PM1 size fraction. With the exception of titanium (Ti), aluminium (Al) and manganese (Mg), 70 % or more of the trace metal species detected were in the smaller size fractions, which indicated the influence of industrial activities. However, the large influence of wind-blown dust was reflected by 30 % or more of trace metals being present in the PM2. 5-10 size fraction. Comparison of trace metals determined at Welgegund to those in the western Bushveld Igneous Complex indicated that at both locations similar species were observed, with Fe being the most abundant. However, concentrations of these trace metal species were significantly higher in the western Bushveld Igneous Complex. Fe concentrations at the Vaal Triangle were similar to levels thereof at Welgegund, while concentrations of species associated with pyrometallurgical smelting were lower. Annual average Ni was 4 times higher, and annual average As was marginally higher than their respective European standard values, which could be attributed to regional influence of pyrometallurgical industries in the western Bushveld Igneous Complex. All three size fractions indicated elevated trace metal concentrations coinciding with the end of the dry season, which could partially be attributed to decreased wet removal and increases in wind generation of particulates. Principal component factor analysis (PCFA) revealed four meaningful factors in the PM1 size fraction, i.e. crustal, pyrometallurgical-related and Au slimes dams. No meaningful factors were determined for the PM1-2. 5 and PM2. 5-10 size fractions, which was attributed to the large influence of wind-blown dust on atmospheric trace metals determined at Welgegund. Pollution roses confirmed the influence of wind-blown dust on trace metal concentrations measured at Welgegund, while the impact of industrial activities was also substantiated.

INVESTIGATING OXIDATION MECHANISMS OF HGO IN THE FREE TROPOSPHERE AND ITS INFLUENCE ON LONG RANGE MERCURY TRANSPORT

EPA Science Inventory

ORD initiated automated speciated mercury measurements at the NOAA Mauna Loa Observatory (MLO), a high altitude research station (~11,500 feet) in 2001. Mercury monitoring at MLO was supplemented with trace element aerosol, criteria gas, and gas and particulate halide measurement...

Relation between different metal pollution criteria in sediments and its contribution on assessing toxicity.

PubMed

Alves, Cristina M; Ferreira, Carlos M H; Soares, Helena M V M

2018-05-14

Several tools have been developed and applied to evaluate the metal pollution status of sediments and predict their potential ecological risk assessment. To date, a comprehensive relationship between the information given by these sediment tools for predicting metal bioavailability and the effective toxicity observed is lacking. In this work, the possible inter-correlations between the data outcoming from using several qualitative evaluation tools of the sediment contamination (contamination factor, CF, the enrichment factor, EF, or the geoaccumulation index, Igeo), metal speciation on sediments (evaluated by the modified BCR sequential extraction procedure) and free metal concentrations in pore waters were studied. It was also our aim to evaluate if these assessment tools could be used for predicting the pore waters toxicity data as toxicity proxy. Principal component analysis and cluster analysis revealed that two quality indices used (CF and EF) were highly correlatable with the more labile fractions from BCR sediment speciation. However, neither of these parameters did correlate with the toxicity of pore waters measured by the chronic toxicity (72 h) in Pseudokirchneriella subcapitata. In contrast, the toxic effects of the given total metal load in sediments were better evaluated by using an additive metal approach using pore water free metal concentrations. Copyright © 2018 Elsevier Ltd. All rights reserved.

Trace metal concentrations in tropical mangrove sediments, NE Brazil.

PubMed

Miola, Brígida; Morais, Jáder Onofre de; Pinheiro, Lidriana de Souza

2016-01-15

Sediment cores were taken from the mangroves of the Coreaú River estuary off the northeast coast of Brazil. They were analyzed for grain size, CaCO3, organic matter, and trace metal (Cd, Pb, Zn, Cu, Al, and Fe) contents. Mud texture was the predominant texture. Levels of trace metals in surface sediments indicated strong influence of anthropogenic processes, and diagenetic processes controlled the trace metal enrichment of core sediments of this estuary. The positive relationships between trace metals and Al and Fe indicate that Cu, Zn, Pb, and Cd concentrations are associated mainly with Al and Fe oxy-hydroxides and have natural sources. Copyright © 2015 Elsevier Ltd. All rights reserved.

Selenium speciation in acidic environmental samples: application to acid rain-soil interaction at Mount Etna volcano.

PubMed

Floor, Geerke H; Iglesías, Mònica; Román-Ross, Gabriela; Corvini, Philippe F X; Lenz, Markus

2011-09-01

Speciation plays a crucial role in elemental mobility. However, trace level selenium (Se) speciation analyses in aqueous samples from acidic environments are hampered due to adsorption of the analytes (i.e. selenate, selenite) on precipitates. Such solid phases can form during pH adaptation up till now necessary for chromatographic separation. Thermodynamic calculations in this study predicted that a pH<4 is needed to prevent precipitation of Al and Fe phases. Therefore, a speciation method with a low pH eluent that matches the natural sample pH of acid rain-soil interaction samples from Etna volcano was developed. With a mobile phase containing 20mM ammonium citrate at pH 3, selenate and selenite could be separated in different acidic media (spiked water, rain, soil leachates) in <10 min with a LOQ of 0.2 μg L(-1) using (78)Se for detection. Applying this speciation analysis to study acid rain-soil interaction using synthetic rain based on H(2)SO(4) and soil samples collected at the flanks of Etna volcano demonstrated the dominance of selenate over selenite in leachates from samples collected close to the volcanic craters. This suggests that competitive behavior with sulfate present in acid rain might be a key factor in Se mobilization. The developed speciation method can significantly contribute to understand Se cycling in acidic, Al/Fe rich environments. Copyright © 2011 Elsevier Ltd. All rights reserved.

Arsenate reductase from Thermus thermophilus conjugated to polyethylene glycol-stabilized gold nanospheres allow trace sensing and speciation of arsenic ions.

PubMed

Politi, Jane; Spadavecchia, Jolanda; Fiorentino, Gabriella; Antonucci, Immacolata; De Stefano, Luca

2016-10-01

Water sources pollution by arsenic ions is a serious environmental problem all around the world. Arsenate reductase enzyme (TtArsC) from Thermus thermophilus extremophile bacterium, naturally binds arsenic ions, As(V) and As (III), in aqueous solutions. In this research, TtArsC enzyme adsorption onto hybrid polyethylene glycol-stabilized gold nanoparticles (AuNPs) was studied at different pH values as an innovative nanobiosystem for metal concentration monitoring. Characterizations were performed by UV/Vis and circular dichroism spectroscopies, TEM images and in terms of surface charge changes. The molecular interaction between arsenic ions and the TtArsC-AuNPs nanobiosystem was also monitored at all pH values considered by UV/Vis spectroscopy. Tests performed revealed high sensitivities and limits of detection equal to 10 ± 3 M -12 and 7.7 ± 0.3 M -12 for As(III) and As(V), respectively. © 2016 The Author(s).

Application of polyurethane foam as a sorbent for trace metal pre-concentration — A review

NASA Astrophysics Data System (ADS)

Lemos, V. A.; Santos, M. S.; Santos, E. S.; Santos, M. J. S.; dos Santos, W. N. L.; Souza, A. S.; de Jesus, D. S.; das Virgens, C. F.; Carvalho, M. S.; Oleszczuk, N.; Vale, M. G. R.; Welz, B.; Ferreira, S. L. C.

2007-01-01

The first publication on the use of polyurethane foam (PUF) for sorption processes dates back to 1970, and soon after the material was applied for separation processes. The application of PUF as a sorbent for solid phase extraction of inorganic analytes for separation and pre-concentration purposes is reviewed. The physical and chemical characteristics of PUF (polyether and polyester type) are discussed and an introduction to the characterization of these sorption processes using different types of isotherms is given. Separation and pre-concentration methods using unloaded and loaded PUF in batch and on-line procedures with continuous flow and flow injection systems are presented. Methods for the direct solid sampling analysis of the PUF after pre-concentration are discussed as well as approaches for speciation analysis. Thermodynamic proprieties of some extraction processes are evaluated and the interpretation of determined parameters, such as enthalpy, entropy and Gibbs free energy in light of the physico-chemical processes is explained.

Reactive solute transport in streams: 1. Development of an equilibrium- based model

USGS Publications Warehouse

Runkel, Robert L.; Bencala, Kenneth E.; Broshears, Robert E.; Chapra, Steven C.

1996-01-01

An equilibrium-based solute transport model is developed for the simulation of trace metal fate and transport in streams. The model is formed by coupling a solute transport model with a chemical equilibrium submodel based on MINTEQ. The solute transport model considers the physical processes of advection, dispersion, lateral inflow, and transient storage, while the equilibrium submodel considers the speciation and complexation of aqueous species, precipitation/dissolution and sorption. Within the model, reactions in the water column may result in the formation of solid phases (precipitates and sorbed species) that are subject to downstream transport and settling processes. Solid phases on the streambed may also interact with the water column through dissolution and sorption/desorption reactions. Consideration of both mobile (water-borne) and immobile (streambed) solid phases requires a unique set of governing differential equations and solution techniques that are developed herein. The partial differential equations describing physical transport and the algebraic equations describing chemical equilibria are coupled using the sequential iteration approach.

Using portable X-ray fluorescence spectrometry and GIS to assess environmental risk and identify sources of trace metals in soils of peri-urban areas in the Yangtze Delta region, China.

PubMed

Ran, Jing; Wang, Dejian; Wang, Can; Zhang, Gang; Yao, Lipeng

2014-08-01

Portable X-ray fluorescence (PXRF) spectrometry may be very suitable for a fast and effective environmental assessment and source identification of trace metals in soils. In this study, topsoils (0-10 cm) at 139 sites were in situ scanned for total trace metals (Cr, Cu, Ni, Pb and Zn) and arsenic concentrations by PXRF in a typical town in Yangtze Delta region of Jiangsu province, China. To validate the utility of PXRF, 53 samples were collected from the scanning sites for the determination of selected trace metals using conventional methods. Based on trace metal concentrations detected by in situ PXRF, the contamination extent and sources of trace metals were studied via geo-accumulation index, multivariate analysis and geostatistics. The trace metal concentrations determined by PXRF were similar to those obtained via conventional chemical analysis. The median concentration of As, Cr, Cu, Ni, Pb and Zn in soils were 10.8, 56.4, 41.5, 43.5, 33.5, and 77.7 mg kg(-1), respectively. The distribution patterns of Cr, Cu, Ni, Pb, and Zn were mostly affected by anthropogenic sources, while As was mainly derived from lithogenic sources. Overall, PXRF has been successfully applied to contamination assessment and source identification of trace metals in soils.

Trace metals in fugitive dust from unsurfaced roads in the Viburnum Trend resource mining District of Missouri--implementation of a direct-suspension sampling methodology.

PubMed

Witt, Emitt C; Wronkiewicz, David J; Pavlowsky, Robert T; Shi, Honglan

2013-09-01

Fugitive dust from 18 unsurfaced roadways in Missouri were sampled using a novel cyclonic fugitive dust collector that was designed to obtain suspended bulk samples for analysis. The samples were analyzed for trace metals, Fe and Al, particle sizes, and mineralogy to characterize the similarities and differences between roadways. Thirteen roads were located in the Viburnum Trend (VT) mining district, where there has been a history of contaminant metal loading of local soils; while the remaining five roads were located southwest of the VT district in a similar rural setting, but without any mining or industrial process that might contribute to trace metal enrichment. Comparison of these two groups shows that trace metal concentration is higher for dusts collected in the VT district. Lead is the dominant trace metal found in VT district dusts representing on average 79% of the total trace metal concentration, and was found moderately to strongly enriched relative to unsurfaced roads in the non-VT area. Fugitive road dust concentrations calculated for the VT area substantially exceed the 2008 Federal ambient air standard of 0.15μgm(-3) for Pb. The pattern of trace metal contamination in fugitive dust from VT district roads is similar to trace metal concentrations patterns observed for soils measured more than 40years ago indicating that Pb contamination in the region is persistent as a long-term soil contaminant. Published by Elsevier Ltd.

Sampling and analysis of natural gas trace constituents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Attari, A.; Chao, S.

1993-09-01

Major and minor components of natural gas are routinely analyzed by gas chromatography (GC), using a thermal conductivity (TC). The best results obtained by these methods can report no better than 0.01 mole percent of each measured component. Even the extended method of analysis by flame ionization detector (FID) can only improve on the detection limit of hydrocarbons. The gas industry needs better information on all trace constituents of natural gas, whether native or inadvertently added during gas processing that may adversely influence the operation of equipment or the safety of the consumer. The presence of arsenic and mercury inmore » some gas deposits have now been documented in international literature as causing not only human toxicity but also damaging to the field equipment. Yet, no standard methods of sampling and analysis exist to provide this much needed information. In this paper the authors report the results of a three-year program to develop an extensive array of sampling and analysis methods for speciation and measurement of trace constituents of natural gas. A cryogenic sampler operating at near 200 K ({minus}99 F) and at pipeline pressures up to 12.4 {times} 10{sup 6}Pa (1800 psig) has been developed to preconcentrate and recover all trace constituents with boiling points above butanes. Specific analytical methods have been developed for speciating and measurement of many trace components (corresponding to US EPA air toxics) by GC-AED and GC-MS, and for determining various target compounds by other techniques. Moisture, oxygen and sulfur contents are measured on site using dedicated field instruments. Arsenic, mercury and radon are sampled by specific solid sorbents for subsequent laboratory analysis.« less

Indirect effects of climate change on zinc cycling in sediments: The role of changing water levels.

PubMed

Nedrich, Sara M; Burton, G Allen

2017-09-01

Increased variability in lake and river water levels associated with changing climate could impact the fate and effects of metals in redox-sensitive sediments through the alteration of microbial communities and of acid-base and redox chemistry. The objective of the present study was to determine the influence of water level fluctuation on metal speciation in porewater and predict environmental risk to high-carbonate systems. Using experimental microcosms with sediments collected from 4 metal-contaminated coastal freshwater wetlands in Michigan, USA, we conducted water level fluctuation experiments. Porewater and sediment metals (Ca, Cu, Fe, Mg, Mn, Ni, Zn) and important metal binding phases (iron-oxide speciation, acid-volatile sulfide) were quantified. In a short-term drying (seiche) experiment, there were decreases in all porewater metals after inundation of saturated sediments. During a drought experiment, re-inundation of oxidized sediments increased porewater Cu, Zn, Mg, Ca for most sites. Porewater Zn increased after inundation to levels exceeding the US Environmental Protection Agency threshold for chronic toxicity. These data show that the dissolution of metal carbonates and metal sulfates contributes to metal release after re-flooding and indicate that we might expect increased ecological risk to organisms present in drought-sensitive regions where altered hydroperiods are likely to increase metal bioavailability. Environ Toxicol Chem 2017;36:2456-2464. © 2017 SETAC. © 2017 SETAC.

Temporal assessment of copper speciation, bioavailability and toxicity in UK freshwaters using chemical equilibrium and biotic ligand models: Implications for compliance with copper environmental quality standards.

PubMed

Lathouri, Maria; Korre, Anna

2015-12-15

Although significant progress has been made in understanding how environmental factors modify the speciation, bioavailability and toxicity of metals such as copper in aquatic environments, the current methods used to establish water quality standards do not necessarily consider the different geological and geochemical characteristics of a given site and the factors that affect copper fate, bioavailability potential and toxicity. In addition, the temporal variation in the concentration and bioavailable metal fraction is also important in freshwater systems. The work presented in this paper illustrates the temporal and seasonal variability of a range of water quality parameters, and Cu speciation, bioavailability and toxicity at four freshwaters sites in the UK. Rivers Coquet, Cree, Lower Clyde and Eden (Kent) were selected to cover a broad range of different geochemical environments and site characteristics. The monitoring data used covered a period of around six years at almost monthly intervals. Chemical equilibrium modelling was used to study temporal variations in Cu speciation and was combined with acute toxicity modelling to assess Cu bioavailability for two aquatic species, Daphnia magna and Daphnia pulex. The estimated copper bioavailability, toxicity levels and the corresponding ecosystem risks were analysed in relation to key water quality parameters (alkalinity, pH and DOC). Although copper concentrations did not vary much during the sampling period or between the seasons at the different sites; copper bioavailability varied markedly. In addition, through the chronic-Cu BLM-based on the voluntary risk assessment approach, the potential environmental risk in terms of the chronic toxicity was assessed. A much higher likelihood of toxicity effects was found during the cold period at all sites. It is suggested that besides the metal (copper) concentration in the surface water environment, the variability and seasonality of other important water quality parameters should be considered in setting appropriately protective environmental quality standards for metals. Copyright © 2015 Elsevier B.V. All rights reserved.

Source and Cycling of Trace Metals and Nutrients in a Microbial Coalbed Methane System

NASA Astrophysics Data System (ADS)

Earll, M. M.; Barnhart, E. P.; Ritter, D.; Vinson, D. S.; Orem, W. H.; Vengosh, A.; McIntosh, J. C.

2015-12-01

The source and cycling of trace metals and nutrients in coalbed methane (CBM) systems are controlled by both geochemical processes, such as dissolution or precipitation, and biological mediation by microbial communities. CBM production by the microbes is influenced by trace metals and macronutrients such as nitrogen (N) and phosphate (P). Previous studies have shown the importance of these nutrients to both enhance and inhibit methane production; however, it's not clear whether they are sourced from coal via in-situ biodegradation of organic matter or transported into the seams with groundwater recharge. To address this knowledge gap, trace metal and nutrient geochemistry and the organic content of solid coal and associated groundwater will be investigated across a hydrologic gradient in CBM wells in the Powder River Basin, MT. Sequential dissolution experiments (chemical extraction of organic and inorganic constituents) using 8 core samples of coal and sandstone will provide insight into the presence of trace metals and nutrients in coalbeds, the associated minerals present, and their mobilization. If significant concentrations of N, P, and trace metals are present in core samples, in-situ sourcing of nutrients by microbes is highly probable. The biogeochemical evolution of groundwater, as it relates to trace metal and nutrient cycling by microbial consortia, will be investigated by targeting core-associated coal seams from shallow wells in recharge areas to depths of at least 165 m and across a 28 m vertical profile that include overburden, coal, and underburden. If microbial-limiting trace metals and nutrients are transported into coal seams with groundwater recharge, we would expect to see higher concentrations of trace metals and nutrients in recharge areas compared to deeper coalbeds. The results of this study will provide novel understanding of where trace metals and nutrients are sourced and how they are cycled in CBM systems.

Impact of trace metal concentrations on coccolithophore growth and morphology: laboratory simulations of Cretaceous stress

NASA Astrophysics Data System (ADS)

Faucher, Giulia; Hoffmann, Linn; Bach, Lennart T.; Bottini, Cinzia; Erba, Elisabetta; Riebesell, Ulf

2017-07-01

The Cretaceous ocean witnessed intervals of profound perturbations such as volcanic input of large amounts of CO2, anoxia, eutrophication and introduction of biologically relevant metals. Some of these extreme events were characterized by size reduction and/or morphological changes of a few calcareous nannofossil species. The correspondence between intervals of high trace metal concentrations and coccolith dwarfism suggests a negative effect of these elements on nannoplankton biocalcification processes in past oceans. In order to test this hypothesis, we explored the potential effect of a mixture of trace metals on growth and morphology of four living coccolithophore species, namely Emiliania huxleyi, Gephyrocapsa oceanica, Pleurochrysis carterae and Coccolithus pelagicus. The phylogenetic history of coccolithophores shows that the selected living species are linked to Mesozoic species showing dwarfism under excess metal concentrations. The trace metals tested were chosen to simulate the environmental stress identified in the geological record and upon known trace metal interactions with living coccolithophore algae.Our laboratory experiments demonstrated that elevated trace metal concentrations, similarly to the fossil record, affect coccolithophore algae size and/or weight. Smaller coccoliths were detected in E. huxleyi and C. pelagicus, while coccoliths of G. oceanica showed a decrease in size only at the highest trace metal concentrations. P. carterae coccolith size was unresponsive to changing trace metal concentrations. These differences among species allow discriminating the most- (P. carterae), intermediate- (E. huxleyi and G. oceanica) and least-tolerant (C. pelagicus) taxa. The fossil record and the experimental results converge on a selective response of coccolithophores to metal availability.These species-specific differences must be considered before morphological features of coccoliths are used to reconstruct paleo-chemical conditions.

Trace element release from estuarine sediments of South Mosquito Lagoon near Kennedy Space Center

NASA Technical Reports Server (NTRS)

Menon, M. P.; Ghuman, G. S.; Emeh, C. O.

1979-01-01

Analytical partitioning of four trace metals in estuarine sediments collected from eight sites in South Mosquito Lagoon near Kennedy Space Center, in terms of four different categories was accomplished using four different extraction techniques. The concentrations of the four trace metals, Zn, Mn, Cd, and Cu, released in interstitial water extract, 1 N ammonium acetate extract, conc. HCl extract and fusion extract of sediments as well as their concentrations in water samples collected from the same location were determined using flame atomic absorption technique. From the analytical results the percentages of total amount of each metal distributed among four different categories, interstitial water phase, acetate extractable, acid extractable and detrital crystalline material, were determined. Our results suggest that analytical partitioning of trace metals in estuarine sediments may be used to study the mechanism of incorporation of trace metals with sediments from natural waters. A correlation between the seasonal variation in the concentration of acetate extractable trace metals in the sediment and similar variation in their concentration in water was observed. A mechanism for the release of trace metals from estuarine sediments to natural water is also suggested.

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

PubMed

Horsfall, M; Spiff, A I

2002-09-01

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.

Wash effect of atmospheric trace metals wet deposition and its source characteristic in subtropical watershed in China.

PubMed

Gao, Yang; Hao, Zhuo; Yang, Tiantian; He, Nianpeng; Tian, Jing; Wen, Xuefa

2016-10-01

In order to better understand air pollution in deve-loping regions, such as China, it is important to investigate the wet deposition behavior of atmospheric trace metals and its sources in the subtropical watershed. This paper studies the seasonal change of trace metal concentrations in precipitation and other potential sources in a typical subtropical watershed (Jiazhuhe watershed) located in the downstream of the Yangtze River of China. The results show that typical crustal elements (Al, Fe) and trace element (Zn) have high seasonal variation patterns and these elements have higher contents in precipitation as compared to other metals in Jiazhuhe watershed. In addition, there is no observed Pb in base flow in this study, and the concentration magnitudes of Al, Ba, Fe, Mn, Sr, and Zn in base flow are significantly higher than that of other metals. During different rainfall events, the dynamic export processes are also different for trace metals. The various trace metals dynamic export processes lead to an inconsistent mass first flush and a significant accumulative variance throughout the rainfall events. It is found that in this region, most of the trace metals in precipitation are from anthropogenic emission and marine aerosols brought by typhoon and monsoon.

TOXIC TRACE METALS IN MAMMALIAN HAIR AND NAILS

EPA Science Inventory

Data have been compiled from the available world literature on the accumulation and bioconcentration of selected toxic trace metals in human hair and nails and other mammalian hair, fur, nails, claws, and hoofs. The toxic trace metals and metalloids include antimony, arsenic, bor...

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

USGS Publications Warehouse

Long, E.R.; MacDonald, D.D.; Cubbage, J.C.; Ingersoll, C.G.

1998-01-01

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.

Determination of trace metals in drinking water in Irbid City-Northern Jordan.

PubMed

Alomary, Ahmed

2013-02-01

Drinking water samples from Irbid, the second populated city in Jordan were analyzed for trace metals (As, Ba, Cd, Pb, Cr, Cu, Fe, Zn, Mn, Ni, and Se) content. The study was undertaken to determine if the metal concentrations were within the national and international guidelines. A total of 90 drinking water samples were collected from Al-Yarmouk University area. The samples were collected from three different water types: tap water (TW), home-purified water (HPW), and plant-purified water (PPW). All the samples were analyzed for trace metals using an inductively coupled plasma-optical emission spectrometry. All the samples analyzed were within the United States Environmental Protection Agency admissible pH limit (6.5-8.5). The results showed that concentrations of the trace metals vary significantly between the three drinking water types. The results showed that HPW samples have the lowest level of trace metals and the concentrations of some essential trace metals in these samples are less than the recommended amounts. Slight differences in the metal contents were found between HPW samples, little differences between PPW samples; however, significant differences were found between TW samples. Although some TW samples showed high levels of trace metals, however, the mean level of most elements determined in the samples were well within the Jordanian standards as well as the World Health Organization standards for drinking water.

Heavy metals in Lake Balaton: water column, suspended matter, sediment and biota.

PubMed

Nguyen, H L; Leermakers, M; Osán, J; Török, S; Baeyens, W

2005-03-20

During the period 1999-2002, five sampling cruises have been carried out on Lake Balaton to assess trace metal distribution in the lake and to identify major sources. Eighteen elements, including Cr, Co, Ni, Cu, Zn, Cd, Pb (trace metals) and Al, Ba, Ca, Fe, K, Mg, Mn, Na, P, S, Sr (major metals), were determined in one or more of the lake's compartments. Lower trace metal concentrations in rainwater were observed in June and February 2000, while much higher levels were present in September 2001 (during a storm event) and in snow (February 2000). In the Northern and Western parts of the lake, especially at the inflow of river Zala and the locations of the yacht harbours, metal concentrations were higher in almost all compartments. Because the lake is very shallow, storm conditions also change significantly the metal distributions in the dissolved and particulate phases. The Kis-Balaton protection system located on Zala river functions very efficiently for retaining suspended particulate matter (SPM; 72% retention) and associated metals. Metal concentrations in surface sediments of the lake showed a high variability. After normalisation for the fine sediment fraction, only a few stations including Zala mouth appeared to be enriched in trace metals. In zooplankton, Zn seemed to be much more elevated compared to the other trace metals. Based on the molar ratios of the trace metals in the various compartments and input flows of the lake, several trends could be deduced. For example, molar ratios of the trace metals in the dissolved and solid (suspended particulate matter and sediments) phases in the lake are fairly similar to those in Zala River.

IN VIVO SYNCHROTRON STUDY OF THALLIUM SPECIATION AND COMPARTMENTATION IN IBERIS INTERMEDIA

EPA Science Inventory

Thallium (TI) is a metal of great toxicological concern and its prevalence in the natural environment has steadily increased as a result of manufacturing and combustion practices. Due to its low natural abundance and increasing demand, TI is the fourth most expensive metal, thus,...

Iron Drinking Water Pipe Corrosion Products: Concentrators of Toxic Metals

DTIC Science & Technology

2013-01-01

health risk. In addition Pb corrosion products may be sinks for other metals such as chromium (Cr), copper (Cu), manganese (Mn), and zinc (Zn). These...Vanadium K-Edge X-ray Absorption Near-Edge Structure Interpretation: Application to the Speciation of Vanadium in Oxide Phases from Steel Slag ’, Journal

Sample preparation and storage can change arsenic speciation in human urine.

PubMed

Feldmann, J; Lai, V W; Cullen, W R; Ma, M; Lu, X; Le, X C

1999-11-01

Stability of chemical speciation during sample handling and storage is a prerequisite to obtaining reliable results of trace element speciation analysis. There is no comprehensive information on the stability of common arsenic species, such as inorganic arsenite [As(III)], arsenate [As(V)], monomethylarsonic acid, dimethylarsinic acid, and arsenobetaine, in human urine. We compared the effects of the following storage conditions on the stability of these arsenic species: temperature (25, 4, and -20 degrees C), storage time (1, 2, 4, and 8 months), and the use of additives (HCl, sodium azide, benzoic acid, benzyltrimethylammonium chloride, and cetylpyridinium chloride). HPLC with both inductively coupled plasma mass spectrometry and hydride generation atomic fluorescence detection techniques were used for the speciation of arsenic. We found that all five of the arsenic species were stable for up to 2 months when urine samples were stored at 4 and -20 degrees C without any additives. For longer period of storage (4 and 8 months), the stability of arsenic species was dependent on urine matrices. Whereas the arsenic speciation in some urine samples was stable for the entire 8 months at both 4 and -20 degrees C, other urine samples stored under identical conditions showed substantial changes in the concentration of As(III), As(V), monomethylarsonic acid, and dimethylarsinic acid. The use of additives did not improve the stability of arsenic speciation in urine. The addition of 0.1 mol/L HCl (final concentration) to urine samples produced relative changes in inorganic As(III) and As(V) concentrations. Low temperature (4 and -20 degrees C) conditions are suitable for the storage of urine samples for up to 2 months. Untreated samples maintain their concentration of arsenic species, and additives have no particular benefit. Strong acidification is not appropriate for speciation analysis.

Competitive and Cooperative Effects during Nickel Adsorption to Iron Oxides in the Presence of Oxalate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flynn, Elaine D.; Catalano, Jeffrey G.

Iron oxides are ubiquitous in soils and sediments and play a critical role in the geochemical distribution of trace elements and heavy metals via adsorption and coprecipitation. The presence of organic acids may potentially alter how metals associate with iron oxide minerals through a series of cooperative or competitive processes: solution complexation, ternary surface complexation, and surface site competition. The macroscopic and molecular-scale effects of these processes were investigated for Ni adsorption to hematite and goethite at pH 7 in the presence of oxalate. The addition of this organic acid suppresses Ni uptake on both minerals. Aqueous speciation suggests thatmore » this is dominantly the result of oxalate complexing and solubilizing Ni. Comparison of the Ni surface coverage to the concentration of free (uncomplexed) Ni 2+ in solution suggests that the oxalate also alters Ni adsorption affinity. EXAFS and ATR-FTIR spectroscopies indicate that these changes in binding affinity are due to the formation of Ni–oxalate ternary surface complexes. These observations demonstrate that competition between dissolved oxalate and the mineral surface for Ni overwhelms the enhancement in adsorption associated with ternary complexation. Oxalate thus largely enhances Ni mobility, thereby increasing micronutrient bioavailability and inhibiting contaminant sequestration.« less

Distribution and Potential Toxicity of Trace Metals in the Surface Sediments of Sundarban Mangrove Ecosystem, Bangladesh

NASA Astrophysics Data System (ADS)

Kumar, A.; Ramanathan, A.; Mathukumalli, B. K. P.; Datta, D. K.

2014-12-01

The distribution, enrichment and ecotoxocity potential of Bangladesh part of Sundarban mangrove was investigated for eight trace metals (As, Cd, Cr, Cu, Fe, Mn, Pb and Zn) using sediment quality assessment indices. The average concentration of trace metals in the sediments exceeded the crustal abundance suggesting sources other than natural in origin. Additionally, the trace metals profile may be a reflection of socio-economic development in the vicinity of Sundarban which further attributes trace metals abundance to the anthropogenic inputs. Geoaccumulation index suggests moderately polluted sediment quality w.r.t. Ni and As and background concentrations for Al, Fe, Mn, Cu, Zn, Pb, Co, As and Cd. Contamination factor analysis suggested low contamination by Zn, Cr, Co and Cd, moderate by Fe, Mn, Cu and Pb while Ni and As show considerable and high contamination, respectively. Enrichment factors for Ni, Pb and As suggests high contamination from either biota or anthropogenic inputs besides natural enrichment. As per the three sediment quality guidelines, Fe, Mn, Cu, Ni, Co and As would be more of a concern with respect to ecotoxicological risk in the Sundarban mangroves. The correlation between various physiochemical variables and trace metals suggested significant role of fine grained particles (clay) in trace metal distribution whereas owing to low organic carbon content in the region the organic complexation may not be playing significant role in trace metal distribution in the Sundarban mangroves.

The biogeochemical distribution of trace elements in the Indian Ocean

NASA Astrophysics Data System (ADS)

Saager, Paul M.

1994-06-01

The present review deals with the distributions of dissolved trace metals in the Indian Ocean in relation with biological, chemical and hydrographic processes. The literature data-base is extremely limited and almost no information is available on particle processes and input and output processes of trace metals in the Indian Ocean basin and therefore much research is needed to expand our understanding of the marine chemistries of most trace metals. An area of special interest for future research is the Arabian Sea. The local conditions (upwelling induced productivity, restricted bottom water circulation and suboxic intermediate waters) create a natural laboratory for studying trace metal chemistry.

The value of metals bioavailability and speciation information for ecological risk assessment in arid soils.

PubMed

Suedel, Burton C; Nicholson, Andrew; Day, Christopher H; Spicer, James

2006-10-01

When evaluating the risk chemicals may pose to mammals and birds in ecological risk assessments (ERAs), it is common practice to conservatively assume that all (100%) of a chemical in an environmental medium is bioavailable to receptors. This assumption often leads to overestimating ecological risk and may ultimately result in costly and unnecessary risk management actions. While effects of bioavailability and speciation of metals such as arsenic (As) and lead (Pb) have been considered in human health risk assessment, these effects are rarely taken into consideration when assessing risks to mammals and birds. An ERA was conducted at the former Col-Tex refinery site in Colorado City, Texas, USA, to characterize risks to select wildlife species from exposure to chromium (Cr) and Pb found in soils. The focus on these metals was based on results of a screening-level ERA that found that Cr and Pb were posing ecological risks at the site. Soils were analyzed for total Cr and Pb, trivalent Cr (CrIII), hexavalent Cr (CrVI), organic Pb, and the bioavailability and speciation of Pb. Results for Pb and Cr indicated that >94% of the Cr was present as the less toxic and immobile Cr(III) and that >99% of the Pb in soils was present as inorganic Pb. Lead bioaccessibility measured by in vitro testing ranged from 8% to 77.8%, depending on location of individual soil samples. Results demonstrated that Pb and Cr bioavailability and speciation information can raise soil cleanup concentrations while being protective of ecological receptors. The costs of performing the ERA were de minimus compared to the reduction in remediation costs at the site. The refined hazard estimates allowed informed decision making in the management and segregation of soils, allowing for effective risk management at the site.

Aluminum, iron, lead, cadmium, copper, zinc, chromium, magnesium, strontium, and calcium content in bone of end-stage renal failure patients.

PubMed

D'Haese, P C; Couttenye, M M; Lamberts, L V; Elseviers, M M; Goodman, W G; Schrooten, I; Cabrera, W E; De Broe, M E

1999-09-01

Little is known about trace metal alterations in the bones of dialysis patients or whether particular types of renal osteodystrophy are associated with either increased or decreased skeletal concentrations of trace elements. Because these patients are at risk for alterations of trace elements as well as for morbidity from skeletal disorders, we measured trace elements in bone of patients with end-stage renal disease. We analyzed bone biopsies of 100 end-stage renal failure patients enrolled in a hemodialysis program. The trace metal contents of bone biopsies with histological features of either osteomalacia, adynamic bone disease, mixed lesion, normal histology, or hyperparathyroidism were compared with each other and with the trace metal contents of bone of subjects with normal renal function. Trace metals were measured by atomic absorption spectrometry. The concentrations of aluminum, chromium, and cadmium were increased in bone of end-stage renal failure patients. Comparing the trace metal/calcium ratio, significantly higher values were found for the bone chromium/calcium, aluminum/calcium, zinc/calcium, magnesium/calcium, and strontium/calcium ratios. Among types of renal osteodystrophy, increased bone aluminum, lead, and strontium concentrations and strontium/calcium and aluminum/calcium ratios were found in dialysis patients with osteomalacia vs the other types of renal osteodystrophy considered as one group. Moreover, the concentrations of several trace elements in bone were significantly correlated with each other. Bone aluminum was correlated with the time on dialysis, whereas bone iron, aluminum, magnesium, and strontium tended to be associated with patient age. Bone trace metal concentrations did not depend on vitamin D intake nor on the patients' gender. The concentration of several trace elements in bone of end-stage renal failure patients is disturbed, and some of the trace metals under study might share pathways of absorption, distribution, and accumulation. The clinical significance of the increased/decreased concentrations of several trace elements other than aluminum in bone of dialysis patients deserves further investigation.

Arsenic Speciation of Terrestrial Invertebrates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moriarty, M.M.; Koch, I.; Gordon, R.A.

2009-07-01

The distribution and chemical form (speciation) of arsenic in terrestrial food chains determines both the amount of arsenic available to higher organisms, and the toxicity of this metalloid in affected ecosystems. Invertebrates are part of complex terrestrial food webs. This paper provides arsenic concentrations and arsenic speciation profiles for eight orders of terrestrial invertebrates collected at three historical gold mine sites and one background site in Nova Scotia, Canada. Total arsenic concentrations, determined by inductively coupled plasma mass spectrometry (ICP-MS), were dependent upon the classification of invertebrate. Arsenic species were determined by high-performance liquid chromatography (HPLC) ICP-MS and X-ray absorptionmore » spectroscopy (XAS). Invertebrates were found by HPLC ICP-MS to contain predominantly arsenite and arsenate in methanol/water extracts, while XAS revealed that most arsenic is bound to sulfur in vivo. Examination of the spatial distribution of arsenic within an ant tissue highlighted the differences between exogenous and endogenous arsenic, as well as the extent to which arsenic is transformed upon ingestion. Similar arsenic speciation patterns for invertebrate groups were observed across sites. Trace amounts of arsenobetaine and arsenocholine were identified in slugs, ants, and spiders.« less

[XANES study of lead speciation in duckweed].

PubMed

Chu, Bin-Bin; Luo, Li-Qiang; Xu, Tao; Yuan, Jing; Sun, Jian-Ling; Zeng, Yuan; Ma, Yan-Hong; Yi, Shan

2012-07-01

Qixiashan lead-zinc mine of Nanjing was one of the largest lead zinc deposits in East China Its exploitation has been over 50 years, and the environmental pollution has also been increasing. The lead concentration in the local environment was high, but lead migration and toxic mechanism has not been clear. Therefore, biogeochemistry research of the lead zinc mine was carried out. Using ICP-MS and Pb-L III edge XANES, lead concentration and speciation were analyzed respectively, and duckweed which can tolerate and enriched heavy metals was found in the pollution area. The results showed that the lead concentration of duckweed was 39.4 mg x kg(-1). XANES analysis and linear combination fit indicated that lead stearate and lead sulfide accounted for 65% and 36.9% respectively in the lead speciation of duckweed, suggesting that the main lead speciation of duckweed was sulfur-containing lead-organic acid.

Sulfur redox chemistry governs diurnal antimony and arsenic cycles at Champagne Pool, Waiotapu, New Zealand

NASA Astrophysics Data System (ADS)

Ullrich, Maria K.; Pope, James G.; Seward, Terry M.; Wilson, Nathaniel; Planer-Friedrich, Britta

2013-07-01

Champagne Pool, a sulfidic hot spring in New Zealand, exhibits distinct diurnal variations in antimony (Sb) and arsenic (As) concentrations, with daytime high and night-time low concentrations. To identify the underlying mobilization mechanisms, five sites along the drainage channel of Champagne Pool were sampled every 2 h during a 24 h period. Temporal variations in elemental concentrations and Sb, As, and sulfur (S) speciation were monitored in the discharging fluid. Total trace element concentrations in filtered and unfiltered samples were analyzed using ICP-MS, and Sb, As and S species were determined by IC-ICP-MS. Sulfur speciation in the drainage channel was dominated by thiosulfate and sulfide at night, while sulfate dominated during the day. The distinct diurnal changes suggest that the transformations are caused by phototrophic sulfur-oxidizing bacteria. These bacteria metabolize thiosulfate and sulfide in daylight to form sulfate and, as suggested by modeling with PhreeqC, elemental sulfur. Sulfide consumption during the day results in undersaturation of antimony sulfides, which triggers the additional release of dissolved Sb. For As, diurnal cycles were much more pronounced in speciation than in total concentrations, with di- and trithioarsenate forming at night due to excess sulfide, and monothioarsenate forming from arsenite and elemental sulfur during the day. Sulfur speciation was thus found to control Sb and As in terms of both solubility and speciation.

Microbial Influences on Trace Metal Cycling in a Meromictic Lake, Fayetteville Green Lake, NY

NASA Astrophysics Data System (ADS)

Zerkle, A. L.; House, C.; Kump, L.

2002-12-01

Microorganisms can exist in aquatic environments at very high cell densities of up to 1011 cells/L, and can accumulate significant quantities of trace metals. Bacteria actively take up bioactive trace metals, including Fe, Zn, Mn, Co, Ni, Cu, and Mo, which function as catalytic centers in metalloproteins and metal-activated enzymes involved in virtually all cellular functions. In addition, bacteria may catalyze the release of trace metals from inorganic substrates by processes such as the reduction of iron and manganese oxides, suggesting that trace metal distributions within a natural environment dominated by microbial processes may be controlled primarily by microbial ecology. Fayetteville Green Lake (FGL), NY, is a permanently stratified meromictic lake that has a well-oxygenated surface water mass (mixolimnion) overlying a relatively stagnant, anoxic deep water mass (monimolimnion). A chemocline separates the water masses at around 20m depth, where oxygen concentrations decrease and sulfate and methane concentrations increase. In addition, previous studies have indicated that trace metals such as V, Cr, Co, Mn, and Fe reach elevated concentrations at the chemocline. Using fluorescent in situ hybridization (FISH) of FGL samples from depths of up to 40m with bacterial and archaeal probes, we have shown that fluctuating redox conditions within the FGL water column correlate with significant variations in the composition and distribution of microbial populations with depth. The mixolimnion is dominated by Eubacteria, with increasing concentrations of Archaea in the lower anoxic zone. Increases in microbial cell densities coincide with increases in trace metals at the chemocline, suggesting microbial activity may be responsible for trace metal release at this boundary. 16S rRNA PCR cloning techniques are currently being used to identify dominant microbial populations at various levels within the FGL water column. Future studies will focus on the potential for these dominant microorganisms to influence trace metal cycling and bioavailability in the FGL water column.

Use of portable X-ray fluorescence spectroscopy and geostatistics for health risk assessment.

PubMed

Yang, Meng; Wang, Cheng; Yang, Zhao-Ping; Yan, Nan; Li, Feng-Ying; Diao, Yi-Wei; Chen, Min-Dong; Li, Hui-Ming; Wang, Jin-Hua; Qian, Xin

2018-05-30

Laboratory analysis of trace metals using inductively coupled plasma (ICP) spectroscopy is not cost effective, and the complex spatial distribution of soil trace metals makes their spatial analysis and prediction problematic. Thus, for the health risk assessment of exposure to trace metals in soils, portable X-ray fluorescence (PXRF) spectroscopy was used to replace ICP spectroscopy for metal analysis, and robust geostatistical methods were used to identify spatial outliers in trace metal concentrations and to map trace metal distributions. A case study was carried out around an industrial area in Nanjing, China. The results showed that PXRF spectroscopy provided results for trace metal (Cu, Ni, Pb and Zn) levels comparable to ICP spectroscopy. The results of the health risk assessment showed that Ni posed a higher non-carcinogenic risk than Cu, Pb and Zn, indicating a higher priority of concern than the other elements. Sampling locations associated with adverse health effects were identified as 'hotspots', and high-risk areas were delineated from risk maps. These 'hotspots' and high-risk areas were in close proximity to and downwind from petrochemical plants, indicating the dominant role of industrial activities as the major sources of trace metals in soils. The approach used in this study could be adopted as a cost-effective methodology for screening 'hotspots' and priority areas of concern for cost-efficient health risk management. Copyright © 2018 Elsevier Inc. All rights reserved.

Trace metal fractionation as a mean to improve on the management of contaminated sediments from runoff water in infiltration basins.

PubMed

Al Husseini, Amelène El-Mufleh; Béchet, Béatrice; Gaudin, Anne; Ruban, Véronique

2013-01-01

The management of stormwater sediment is a key issue for local authorities due to the pollution load and significant tonnages. In view of reuse, for example for civil engineering, the environmental evaluation of these highly aggregated sediments requires the study of the fractionation and mobility of trace metals. The distribution of trace metals (Cd, Cr, Cu, Ni, Pb, Zn) and their level of lability in three French stormwater sediments was determined using sequential and kinetic extractions (EDTA reagent) associated with mineralogical analysis and scanning electron microscopy observations. Using microanalysis, new data were acquired on the evolution of aggregate state during extractions, and on its significant role in the retention of trace metals. Trace metals were, in particular, observed to be very stable in small aggregates (10-50 microm). Comparison of the two extraction methods revealed that EDTA extraction was not convenient for evaluating the stable fraction of Cr, Ni and Zn. Moreover, the results were relevant for basins presenting similar sources of trace metals, whatever the physicochemical conditions in basins. The results suggest that the management of stormwater sediments could be improved by a better knowledge of metal mobility, as chemical extractions could highlight the localization of the mobile fraction of trace metals. Treatment could be therefore avoided, or specific treatment could be applied to a reduced volume of sediments.

Analytical Methods for Trace Metals. Training Manual.

ERIC Educational Resources Information Center

Office of Water Program Operations (EPA), Cincinnati, OH. National Training and Operational Technology Center.

This training manual presents material on the theoretical concepts involved in the methods listed in the Federal Register as approved for determination of trace metals. Emphasis is on laboratory operations. This course is intended for chemists and technicians with little or no experience in analytical methods for trace metals. Students should have…

Importance of reduced sulfur for the equilibrium chemistry and kinetics of Fe(II), Co(II) and Ni(II) supplemented to semi-continuous stirred tank biogas reactors fed with stillage.

PubMed

Shakeri Yekta, Sepehr; Lindmark, Amanda; Skyllberg, Ulf; Danielsson, Asa; Svensson, Bo H

2014-03-30

The objective of the present study was to assess major chemical reactions and chemical forms contributing to solubility and speciation of Fe(II), Co(II), and Ni(II) during anaerobic digestion of sulfur (S)-rich stillage in semi-continuous stirred tank biogas reactors (SCSTR). These metals are essential supplements for efficient and stable performance of stillage-fed SCSTR. In particular, the influence of reduced inorganic and organic S species on kinetics and thermodynamics of the metals and their partitioning between aqueous and solid phases were investigated. Solid phase S speciation was determined by use of S K-edge X-ray absorption near-edge spectroscopy. Results demonstrated that the solubility and speciation of supplemented Fe were controlled by precipitation of FeS(s) and formation of the aqueous complexes of Fe-sulfide and Fe-thiol. The relatively high solubility of Co (∼ 20% of total Co content) was attributed to the formation of compounds other than Co-sulfide and Co-thiol, presumably of microbial origin. Nickel had lower solubility than Co and its speciation was regulated by interactions with FeS(s) (e.g. co-precipitation, adsorption, and ion substitution) in addition to precipitation/dissolution of discrete NiS(s) phase and formation of aqueous Ni-sulfide complexes. Copyright © 2014 Elsevier B.V. All rights reserved.

Geochemistry of organic carbon and trace elements in boreal stratified lakes during different seasons

NASA Astrophysics Data System (ADS)

Moreva, O. Y.; Pokrovsky, O. S.; Shirokova, L. S.; Viers, J.

2008-12-01

Our knowledge of chemical fluxes in the system rock-soils-rivers-ocean of boreal and glacial landscapes is limited by the least studied part, i.e., the river water transformation between the lake and the river systems. Dissolved organic carbon (DOC), nutrients, major and trace elements are being leached from soil profile to the river but subjected to chemical transformation in the lakes due to phytoplankton and bacterial activity. As a result, many lakes in boreal regions are quite different in chemical composition compared to surrounding rivers and demonstrate important chemical stratification. The main processes responsible for chemical stratification in lakes are considered to be i) diffusion fluxes from the sediment to the bottom water accompanied by sulfate reduction and methanogenesis in the sediments and ii) dissolution/mineralization of precipitating organic matter (mineral fraction, detritus, plankton pellets) in the bottom layer horizons under anoxic conditions. Up to present time, distinguishing between two processes remains difficult. This paper is aimed at filling this gap via detailed geochemical analysis of DOC and trace elements in the water column profiles of three typical stratified lakes of Arkhangelsk region in Kenozersky National Parc (64° N) in winter (glacial) and in summer period. Concentration of most trace elements (Li, B, Al, Ti, V, Cr, Ni, Co, Zn, As, Rb, Sr, Y, Zr, Mo, Sb, Ba, REEs, Th, U) are not subjected to strong variations along the water column, despite the presence of strong or partial redox stratification. Apparently, these elements are not significantly controlled by production/mineralization processes and redox phenomena in the water column, or the influence of these processes is not pronounced under the control by the allochtonous river water input. In particularly, the stability of titanium and aluminum concentration along the depth profile and their independence of iron behavior suggest the important control by dissolved organic matter. Therefore, organo-ferric colloids controlling petrogenic elements speciation in soil and river waters are being replaced by autochthonous organic colloids in the lake system. The same observation is true for some heavy metals such as nickel, copper and zinc, whereas cobalt, as limiting component, is being strongly removed from the photic zone or it is coprecipitating with manganese hydroxide. Results of the present work allow quantitative evaluation of the role of redox processes in the bottom horizons and organic detritus degradation in the creation of chemical stratification of small lakes with high DOC concentration. Further insights on geochemical migration of trace elements in lakes require : i) study of colloidal speciation using in-situ dialysis; ii) monitoring the annual and seasonal dynamics of redox processes and TE concentration variation along the profile; iii) quantitative assessment of bacterial degradation of suspended OM and Mn and Fe redox reactions along the depth profile; iv) setting the sedimentary traps for evaluation of suspended material fluxes, and, v) thorough study of chemical composition of interstitial pore waters.

Factors affecting fixation of heavy metals in solidified/stabilized matrix: a review.

PubMed

Malviya, Rachana; Chaudhary, Rubina

2010-07-01

In this paper, an effort has been made to understand the factors, which affect fixation of heavy metals in solidified/stabilized matrix. Various aspects related to the solidification/stabilization of different heavy metals (Ar, Ba, Cu, Cr, Pb, Zn, Hg) are reviewed. A comparative study of different binders for the fixation of each metal has also been carried out to suggest the most suitable binder, pretreatment required for the metal. Valence, speciation, pH and other factors are also considered while reviewing metal retention capacity of different matrix.

Trace metals in upland headwater lakes in Ireland.

PubMed

Burton, Andrew; Aherne, Julian; Hassan, Nouri

2013-10-01

Trace elements (n = 23) in Irish headwater lakes (n = 126) were investigated to determine their ambient concentrations, fractionation (total, dissolved, and non-labile), and geochemical controls. Lakes were generally located in remote upland, acid-sensitive regions along the coastal margins of the country. Total trace metal concentrations were low, within the range of natural pristine surface waters; however, some lakes (~20 %) had inorganic labile aluminum and manganese at levels potentially harmful to aquatic organisms. Redundancy analysis indicated that geochemical weathering was the dominant controlling factor for total metals, compared with acidity for dissolved metals. In addition, many metals were positively correlated with dissolved organic carbon indicating their affinity (or complexation) with humic substances (e.g., aluminum, iron, mercury, lead). However, a number of trace metals (e.g., aluminum, mercury, zinc) were correlated with anthropogenic acidic deposition (i.e., non-marine sulfate), suggesting atmospheric sources or elevated leaching owing to acidic deposition. As transboundary air pollution continues to decline, significant changes in the cycling of trace metals is anticipated.

Trace metal accumulation in sediments and benthic macroinvertebrates before and after maintenance of a constructed wetland.

PubMed

O'Connor, Thomas P; Muthukrishnan, Swarna; Barshatzky, Kristen; Wallace, William

2012-04-01

Stormwater best management practices (BMPs) require regular maintenance. The impact on trace metal concentrations in a constructed stormwater wetland BMP on Staten Island, New York, was investigated by analyzing sediment concentrations and tissue residues of the dominant macroinvertebrates (Tubifex tubifex) prior and subsequent to maintenance. Trace metal concentrations were assessed using standard serial extraction (for sediment) and acid digestion (for tissue burdens) techniques, followed by quantitative determination using graphite furnace atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry, respectively. The results suggest that disturbance of sediment during maintenance of the BMP resulted in an increase in the most mobile fraction of trace metals, especially those associated with finer grained sediments (< 63 tm), and as a consequence, measured metal concentrations in macroinvertebrates increased. Regressions of a subset of metal concentrations (copper, lead, and zinc) in sediment and the macroinvertebrate tissue burden samples generally increased as a result of maintenance. A follow-up sampling event 9 months after maintenance demonstrated that the most readily available form of trace metal in the BMP was reduced, which supports (1) long-term sequestration of metals in the BMP and (2) that elevated bioavailability following maintenance was potentially a transient feature of the disturbance. This study suggests that in the long-term, performing sediment removal might help reduce bioavailability of trace metal concentrations in both the BMP and the receiving water to which a BMP discharges. However, alternative practices might need to be implemented to reduce trace metal bioavailability in the short-term.

Trace-metal concentrations, waters from selected sky lakes, streams and springs, northern Shawangunk Mountains, New York: geologic and ecologic implications

USGS Publications Warehouse

Friedman, J.D.; Huth, P.C.; Smiley, D.

1990-01-01

Reconnaissance sampling and chemical analysis of water from selected lakes, streams and springs of the northern Shawangunk Mountains in 1987 to 1988 to determine the influence of lithology on trace-metal concentrations in surface water, and to establish a base level of concentration of 27 selected metals by ICP-AES and Hg by cold-vapor AAS methods, for geochemical exploration, ecologic, acid-rain, and climatic-change studies, have yielded trace-metal concentrations greater than detection limits for 10 metallic elements. Eighteen additional metallic elements were also present in trace quantities below the quantitative detection limit. Two distinct geochemical populations are related to source lithology and pH. -from Authors

Comparing WHAM 6 and MINEQL+ 4.5 for the chemical speciation of Cu2+ in the rhizosphere of forest soils.

PubMed

Cloutier-Hurteau, Benoît; Sauvé, Sébastien; Courchesne, François

2007-12-01

Metal speciation data calculated by modeling could give useful information regarding the fate of metals in the rhizospheric environment. However, no comparative study has evaluated the relative accuracy of speciation models in this microenvironment. Consequently, the present study evaluates the reliability of free Cu ion (Cu2+) activity modeled by WHAM 6 and MINEQL+ 4.5 for 18 bulk and 18 rhizospheric soil samples collected in two Canadian forested areas located near industrial facilities. The modeling of Cu speciation was performed on water extracts using pH, dissolved organic carbon (DOC), major ions, and total dissolved Al, Ca, Cu, Mg, and Zn concentrations as input data. Four scenarios representing the composition of dissolved organic substances using fulvic, humic, and acetic acids were derived from the literature and used in the modeling exercise. Different scenarios were used to contrast soil components (rhizosphere vs bulk) and soil pH levels (acidic vs neutral to alkaline). Reference Cu2+ activity values measured by an ion-selective electrode varied between 0.39 and 41 nM. The model MINEQL+ 4.5 provided good predictions of Cu2+ activities [root-mean-square residual (RMSR)= 0.37], while predictions from WHAM 6 were poor (RMSR = 1.74) because they overestimated Cu complexation with DOC. Modeling with WHAM 6 could be improved by adjusting the proportion of inert DOC and the composition of DOC (RMSR = 0.94), but it remained weaker than predictions with MINEQL+ 4.5. These results suggested that the discrepancies between speciation models were attributed to differences in the binding capacity of humic substances with Cu, where WHAM 6 appeared to be too aggressive. Therefore, we concluded that chemical interactions occurring between Cu and DOC were key factors for an accurate simulation of Cu speciation, especially in rhizospheric forest soils, where high variation of the DOC concentration and composition are observed.

Chemical characterization of ambient aerosol collected during the southwest monsoon and intermonsoon seasons over the Arabian Sea: Labile-Fe(II) and other trace metals

NASA Astrophysics Data System (ADS)

Siefert, Ronald L.; Johansen, Anne M.; Hoffmann, Michael R.

1999-02-01

Atmospheric deposition of iron (Fe) to certain regions of the oceans is an important nutrient source of Fe to the biota, and the ability of the biota to uptake Fe is dependent on the speciation of the Fe. Therefore understanding the speciation of Fe in the atmosphere is critical to understanding the role of Fe as a nutrient source in surface ocean waters. Labile ferrous iron (Fe(II)) concentrations as well as total concentrations for Fe and other important trace metals, cations, and anions were determined over the Arabian Sea for two nonconsecutive months during 1995. Ambient aerosol samples were collected during the Indian Ocean intermonsoon and southwest monsoon seasons over the Arabian Sea. Sampling took place aboard the German research vessel Meteor in the months of May (leg M32/3; intermonsoon) and July/August (leg M32/5; southwest monsoon). Both cruise tracks followed the 65th east meridian, traveling for 30 days each (from north to south during leg M32/3 and from south to north during leg M32/5). A high-volume dichotomous virtual impactor with an aerodynamic cutoff size of 3 μm was used to collect the fine and coarse aerosol fractions for metal analysis. A low volume collector was used to collect aerosol samples for anion and cation analysis. The analysis for labile-Fe(II) was done immediately after sample collection to minimize any possible Fe redox reactions which might occur during sample storage. The analytical procedure involved filter extraction in a formate/formic acid buffered solution at pH 4.2 followed by colorimetric quantification of soluble Fe(II). Metals, anions, and cations were analyzed after the cruise. Total atmospheric aqueous-labile-Fe(II) concentrations during the intermonsoon were between 4.75 and <0.4 ng m-3, of which most (>80%) was present in the fine fraction (<3.0 μm). During the southwest monsoon, atmospheric aqueous-labile-Fe(II) concentrations were consistently below the detection limit (<0.34 to <0.089 ng m-3, depending on the volume of air sampled). Air mass back trajectories (5 day, three dimensional) showed that air masses sampled during the southwest monsoon had advected over the open Indian Ocean, while air masses sampled during the intermonsoon had advected over northeast Africa, the Saudi Arabian peninsula, and southern Asia. These calculations were consistent with the results of the statistical analysis performed on the data set which showed that the variance due to crustal species during the intermonsoon samples was greater than the variance due to crustal species during the southwest monsoon. The factor scores for the crustal components were also greater when the back trajectories had advected over the nearby continental masses. Principal component analysis was also performed with the intermonsoon samples where aqueous labile Fe(II) was above the detection limit. Aqueous labile Fe(II) did not correlate well with other species indicating possible atmospheric processing of the iron during advection.

Determination of trace and heavy metals in some commonly used medicinal herbs in Ayurveda.

PubMed

Nema, Neelesh K; Maity, Niladri; Sarkar, Birendra K; Mukherjee, Pulok K

2014-11-01

Traditionally, the herbal drugs are well established for their therapeutic benefits. Depending upon their geographical sources sometimes the trace and heavy metals' content may differ, which may lead to severe toxicity. So, the toxicological and safety assessment of these herbal drugs are one of the major issues in recent days. Eight different plant species including Aloe vera, Centella asiatica, Calendula officinalis, Cucumis sativus, Camellia sinensis, Clitoria ternatea, Piper betel and Tagetes erecta were selected to determine their heavy and trace metals content and thereby to assure their safer therapeutic application. The trace and heavy metals were detected through atomic absorption spectrometry analysis. The selected medicinal plant materials were collected from the local cultivated regions of West Bengal, India, and were digested with nitric acid and hydrochloric acid as specified. Absorbance was measured through atomic absorption spectrometer (AA 303) and the concentration of different trace and heavy metals in the plant samples were calculated. The quantitative determinations were carried out using standard calibration curve obtained by the standard solutions of different metals. The contents of heavy metals were found to be within the prescribed limit. Other trace metals were found to be present in significant amount. Thus, on the basis of experimental outcome, it can be concluded that the plant materials collected from the specific region are safe and may not produce any harmful effect of metal toxicity during their therapeutic application. The investigated medicinal plants contain trace metals such as copper (Cu), chromium (Cr), manganese (Mn), iron (Fe) and nickel (Ni) as well as heavy metals such as arsenic (As), lead (Pb) and mercury (Hg), which were present within the permissible limit. © The Author(s) 2012.

Assessment of the hazard posed by metal forms in water and sediments.

PubMed

Wojtkowska, Małgorzata; Bogacki, Jan; Witeska, Anna

2016-05-01

This study aimed to describe the prevalence heavy metals (Zn, Cu, Pb, and Cd) forms in the ecosystem of the Utrata river in order to determine the mobile forms and bioavailability of metals. To extract the dissolved forms of metals in the water of the Utrata PHREEQC2 geochemical speciation model was used. The river waters show a high percentage of mobile and eco-toxic forms of Zn, Cu and Pb. The percentage of carbonate forms for all the studied metals was low (<1%). The content of carbonates in the water and the prevailing physical and chemical conditions (pH, hardness, alkalinity) reduce the share of toxic metal forms, which precipitate as hardly soluble carbonate salts of Zn, Cu, Cd and Pb. Cu in the water in 90% of cases appeared in the form of hydroxyl compounds. To identify the forms of metal occurrence in the sediments Tessier's sequential extraction was used, allowing to assay bound metals in five fractions (ion exchange, carbonate, adsorption, organic, residual), whose nature and bioavailability varies in aquatic environments. The study has shown a large share of metals in labile and bioavailable forms. The speciation analysis revealed an absolute dominance of the organic fraction in the binding of Cu and Pb. Potent affinity for this fraction was also exhibited by Cd. The rations of exchangeable Zn and Cu forms in the sediments were similar. Both these metals had the lowest share in the most mobile ion exchange fraction. Copyright © 2016. Published by Elsevier B.V.

Heavy Metals and Related Trace Elements.

ERIC Educational Resources Information Center

Leland, Harry V.; And Others

1978-01-01

Presents a literature review of heavy metals and related trace elements in the environment, covering publications of 1976-77. This review includes: (1) trace treatment in natural water and in sediments; and (2) bioaccumulation and toxicity of trace elements. A list of 466 references is presented. (HM)

Characterization of typical heavy metals in pyrolysis MSWI fly ash.

PubMed

Xu, Tengtun; Wang, Li'ao; Zeng, Yunmin; Zhao, Xue; Wang, Lei; Zhan, Xinyuan; Li, Tong; Yang, Lu

2018-06-07

Thermal treatment methods are used extensively in the process of municipal solid waste incineration fly ash. However, the characterization of heavy metals during this process should be understood more clearly in order to control secondary pollution. In this paper, the content, speciation and leaching toxicity of mercury (Hg), plumbum (Pb), cadmium (Cd) and zinc (Zn) in fly ash treated under different temperatures and time were firstly analysed as pre-tests. Later, pilot-scale pyrolysis equipment was used to explore the concentration and speciation changes in the heavy metals of fly ash. Finally, the phase constitution and microstructure changes in fly ash were compared before and after pyrolysis using X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The results showed that (a) The appropriate processing temperature was between 400°C and 450°C, and the processing time should be 1 h. (b) The stability of heavy metals in fly ash increased after pyrolysis. (c) XRD and SEM results indicated that phase constitution changed a little, but the microstructure varied to a porous structure similar to that of a coral reef after pyrolysis. These results suggest that pyrolysis could be an effective method in controlling heavy metal pollution in fly ash.

Inductively coupled plasma mass spectrometry and electrospray mass spectrometry for speciation analysis: applications and instrumentation

NASA Astrophysics Data System (ADS)

Rosen, Amy L.; Hieftje, Gary M.

2004-02-01

To gain an understanding of the function, toxicity and distribution of trace elements, it is necessary to determine not only the presence and concentration of the elements of interest, but also their speciation, by identifying and characterizing the compounds within which each is present. For sensitive detection of compounds containing elements of interest, inductively coupled plasma mass spectrometry (ICP-MS) is a popular method, and for identification of compounds via determination of molecular weight, electrospray ionization mass spectrometry (ESI-MS) is gaining increasing use. ICP-MS and ESI-MS, usually coupled to a separation technique such as chromatography or capillary electrophoresis, have already been applied to a large number of research problems in such diverse fields as environmental chemistry, nutritional science, and bioinorganic chemistry, but a great deal of work remains to be completed. Current areas of research to which ICP-MS and ESI-MS have been applied are discussed, and the existing instrumentation used to solve speciation problems is described.

Changes in metal availability, desorption kinetics and speciation in contaminated soils during repeated phytoextraction with the Zn/Cd hyperaccumulator Sedum plumbizincicola.

PubMed

Li, Zhu; Jia, Mingyun; Wu, Longhua; Christie, Peter; Luo, Yongming

2016-02-01

Phytoextraction is one of the most promising technologies for the remediation of metal contaminated soils. Changes in soil metal availability during phytoremediation have direct effects on removal efficiency and can also illustrate the interactive mechanisms between hyperaccumulators and metal contaminated soils. In the present study the changes in metal availability, desorption kinetics and speciation in four metal-contaminated soils during repeated phytoextraction by the zinc/cadmium hyperaccumulator Sedum plumbizincicola (S. plumbizincicola) over three years were investigated by chemical extraction and the DGT-induced fluxes in soils (DIFS) model. The available metal fractions (i.e. metal in the soil solution extracted by CaCl2 and by EDTA) decreased greatly by >84% after phytoextraction in acid soils and the deceases were dramatic at the initial stages of phytoextraction. However, the decreases in metal extractable by CaCl2 and EDTA in calcareous soils were not significant or quite low. Large decreases in metal desorption rate constants evaluated by DIFS were found in calcareous soils. Sequential extraction indicated that the acid-soluble metal fraction was easily removed by S. plumbizincicola from acid soils but not from calcareous soils. Reducible and oxidisable metal fractions showed discernible decreases in acid and calcareous soils, indicating that S. plumbizincicola can mobilize non-labile metal for uptake but the residual metal cannot be removed. The results indicate that phytoextraction significantly decreases metal availability by reducing metal pool sizes and/or desorption rates and that S. plumbizincicola plays an important role in the mobilization of less active metal fractions during repeated phytoextraction. Copyright © 2015 Elsevier Ltd. All rights reserved.

Risk assessment of trace metal-polluted coastal sediments on Hainan Island: A full-scale set of 474 geographical locations covering the entire island.

PubMed

Li, Feng; Lin, Ze-Feng; Wen, Jia-Sheng; Wei, Yan-Sha; Gan, Hua-Yang; He, Hai-Jun; Lin, Jin-Qin; Xia, Zhen; Chen, Bi-Shuang; Guo, Wen-Jie; Tan, Cha-Sheng; Cai, Hua-Yang

2017-12-15

Hainan Island is the second largest island and one of the most famous tourist destinations in China, but sediment contamination by trace metals in coastal areas is a major issue. However, full-scale risk assessments of trace metal-polluted coastal sediments are lacking. In this study, coastal surface sediments from 474 geographical locations covering almost the entire island were collected to identify risk-related variables. Controlling factors and possible sources of trace metals were identified, and the toxicity effects were carefully evaluated. Our results suggest that trace-metal pollution in coastal sediments, which was mainly caused by Pb, Zn and Cu emissions, has primarily resulted from industrial sewage and shipping activities and has threatened the offshore ecosystem of Hainan Island and warrants extensive consideration. This is the first study that has systematically investigated trace metal-polluted coastal sediments throughout the entirety of Hainan Island and provides solid evidence for sustainable marine management in the region. Copyright © 2017 Elsevier Ltd. All rights reserved.

Speciation of heavy metals Cu, Ni and Zn by modified BCR sequential extraction procedure in sediments from Banten Bay, Banten Province, Indonesia

NASA Astrophysics Data System (ADS)

Lestari; Budiyanto, F.; Hindarti, D.

2018-02-01

Banten Bay is categorized as a marine area that is busy with marine tourism activities, settlements and also industries. One potential impact of the condition is the occurrence of pollution from both industrial and domestic sources, erosion and sedimentation in the coastal environment. Samples were collected from 25 representative stations in April 2016. Chemical speciation of three heavy metals (Cu, Ni, and Zn) was studied using a modified sequential extraction procedure proposed by the European Standard, Measurements and Testing (SM&T) program, formerly the Community Bureau of Reference (BCR). The aims of this study are to determine geochemical speciation of 4 bounds of metal: acid-soluble, reducible, oxidizable and residual, and to assess their impacts in the sediments of Banten Bay, Indonesia. The result shows that the percentage of Copper (45.90-83.75%), Nickel (18.28-65.66%), and Zinc (30.45-79.51%) were mostly accumulated in residual fraction of the total concentrations. The Risk Assessment Code (RAC) reveals that about 0-7.07% of Copper and 1.11-24.35 % of Zinc at sites exist in exchangeable fraction and therefore, they are in low risk category. While 7.34-34.90 of Ni at sites exists in exchangeable fraction and therefore, it is in medium risk category to aquatic environment.

Prediction of toxicity of zinc and nickel mixtures to Artemia sp. at various salinities: From additivity to antagonism.

PubMed

Damasceno, Évila Pinheiro; de Figuerêdo, Lívia Pitombeira; Pimentel, Marcionília Fernandes; Loureiro, Susana; Costa-Lotufo, Letícia Veras

2017-08-01

Few studies have examined the toxicity of metal mixtures to marine organisms exposed to different salinities. The aim of the present study was to investigate the acute toxicity of zinc and nickel exposures singly and in combination to Artemia sp. under salinities of 10, 17, and 35 psu. The mixture concentrations were determined according to individual toxic units (TUs) to follow a fixed ratio design. Zinc was more toxic than nickel, and both their individual toxicities were higher at lower salinities. These changes in toxicity can be attributed to the Biotic Ligand Model (BLM) rather than to metal speciation. To analyze the mixture effect, the observed data were compared with the expected mixture effects predicted by the concentration addition (CA) model and by deviations for synergistic/antagonistic interactions and dose-level and dose-ratio dependencies. For a salinity of 35 psu, the mixture had no deviations; therefore, the effects were additive. After decreasing the salinity to 17 psu, the toxicity pattern changed to antagonism at low concentrations and synergism at higher equivalent LC 50 levels. For the lowest salinity tested (10 psu), antagonism was observed. The speciations of both metals were similar when in a mixture and when isolated, and changes in toxicity patterns are more related to the organism's physiology than metal speciation. Therefore, besides considering chemical interactions in real-world scenarios, where several chemicals can be present, the influence of abiotic factors, such as salinity, should also be considered. Copyright © 2017 Elsevier Inc. All rights reserved.

Implications for metal and volatile cycles from the pH of subduction zone fluids

NASA Astrophysics Data System (ADS)

Galvez, Matthieu E.; Connolly, James A. D.; Manning, Craig E.

2016-11-01

The chemistry of aqueous fluids controls the transport and exchange—the cycles—of metals and volatile elements on Earth. Subduction zones, where oceanic plates sink into the Earth’s interior, are the most important geodynamic setting for this fluid-mediated chemical exchange. Characterizing the ionic speciation and pH of fluids equilibrated with rocks at subduction zone conditions has long been a major challenge in Earth science. Here we report thermodynamic predictions of fluid-rock equilibria that tie together models of the thermal structure, mineralogy and fluid speciation of subduction zones. We find that the pH of fluids in subducted crustal lithologies is confined to a mildly alkaline range, modulated by rock volatile and chlorine contents. Cold subduction typical of the Phanerozoic eon favours the preservation of oxidized carbon in subducting slabs. In contrast, the pH of mantle wedge fluids is very sensitive to minor variations in rock composition. These variations may be caused by intramantle differentiation, or by infiltration of fluids enriched in alkali components extracted from the subducted crust. The sensitivity of pH to soluble elements in low abundance in the host rocks, such as carbon, alkali metals and halogens, illustrates a feedback between the chemistry of the Earth’s atmosphere-ocean system and the speciation of subduction zone fluids via the composition of the seawater-altered oceanic lithosphere. Our findings provide a perspective on the controlling reactions that have coupled metal and volatile cycles in subduction zones for more than 3 billion years7.

Interactions Among Chemical Speciation, Algal Accumulation, and Biogeochemical Cycling of Toxic Metals in a Major U.S. Naval Harbor (Elizabeth River, VA)

DTIC Science & Technology

2000-09-30

the Elizabeth River/Hampton Roads system and algal species grown in metal ion buffer systems: Thalassiosira pseudonana, Emiliania huxleyi , and...metal ion concentration. 1 10 100 1000 -12 -11 -10 -9 -8 -7 Log [Zn2+] C el l Z n: C ( m ol /m ol ) T. pseudonana E. huxleyi I. galbana Elizabeth River

Bioavailability of cyanide and metal-cyanide mixtures to aquatic life.

PubMed

Redman, Aaron; Santore, Robert

2012-08-01

Cyanide can be toxic to aquatic organisms, and the U.S. Environmental Protection Agency has developed ambient water-quality criteria to protect aquatic life. Recent work suggests that considering free, rather than total, cyanide provides a more accurate measure of the biological effects of cyanides and provides a basis for water-quality criteria. Aquatic organisms are sensitive to free cyanide, although certain metals can form stable complexes and reduce the amount of free cyanide. As a result, total cyanide is less toxic when complexing metals are present. Cyanide is often present in complex effluents, which requires understanding how other components within these complex effluents can affect cyanide speciation and bioavailability. The authors have developed a model to predict the aqueous speciation of cyanide and have shown that this model can predict the toxicity of metal-cyanide complexes in terms of free cyanide in solutions with varying water chemistry. Toxicity endpoints based on total cyanide ranged over several orders of magnitude for various metal-cyanide mixtures. However, predicted free cyanide concentrations among these same tests described the observed toxicity data to within a factor of 2. Aquatic toxicity can be well-described using free cyanide, and under certain conditions the toxicity was jointly described by free cyanide and elevated levels of bioavailable metals. Copyright © 2012 SETAC.

Fate of metals before and after chemical extraction of incinerated sewage sludge ash.

PubMed

Li, Jiang-Shan; Tsang, Daniel C W; Wang, Qi-Ming; Fang, Le; Xue, Qiang; Poon, Chi Sun

2017-11-01

Chemical extraction of incinerated sewage sludge ash (ISSA) can effectively recycle P, but it may change the speciation and mobility of the remaining metals. This study investigated the changes of the leaching potential and distribution of metals in the chemically extracted ISSA. Batch extraction experiments with different extractants, including inorganic acids, organic acids, and chelating agents, were conducted on the ISSA collected from a local sewage sludge incinerator. The extraction of Zn, Cu, Pb, Ni, Cd, Ba, Cr and As from the ISSA and the corresponding changes of the mobility and speciation were examined. The results showed that the metals in ISSA were naturally stable because large portions of metals were associated with the residual fraction. The inorganic (HNO 3 and H 2 SO 4 ) and organic acids (citric acid and oxalic acid) significantly co-dissolved the metals through acid dissolution, but the reduction in the total concentrations did not tally the leaching potential of the residual metals. The increase in the exchangeable fraction due to destabilization by the extractants significantly enhanced the mobility and leachability of the metals in the residual ISSA. Chelating agents (EDTA and EDTMP) only extracted a small quantity of metals and had a marginal effect on the fate of the residual metals, but they significantly reduced the Fe/Mn oxide-bound fraction. In comparison, the bioaccessibility of residual metals were reduced to varying extent. Therefore, the disposal or reuse of chemically extracted ISSA should be carefully evaluated in view of possible increase in mobility of residual metals in the environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Risks of using EDTA as an agent for trace metals dosing in anaerobic digestion of olive mill solid waste.

PubMed

Serrano, A; Pinto-Ibieta, F; Braga, A F M; Jeison, D; Borja, R; Fermoso, F G

2017-12-01

Low concentrations of trace elements in many organic wastes recommend their supplementation in order to avoid potential limitations. Different chelating agents have been used to ensure an adequate trace metal pool in the soluble fraction, by forming dissolved complexes. Ethylenediaminetetraacetic acid (EDTA) is probably the most common, although several negative effects could be associated with its usage. Biomethane potential tests were performed using Olive Mill Solid Waste as the substrate, supplementing different combinations of Fe, Co, Ni, Ba, always under the presence of EDTA. Results show that Ni and Co slightly recovered biodegradability. However, Ba supplementation resulted in worsening the methane yield coefficient in all cases. High concentration of EDTA led to decrease in the activity of anaerobic digestion. High availability of EDTA induces the capture of trace metals like Co or Ni, key trace metals for anaerobic biomass activity. While supplementing trace metals, the addition of Ba and/or EDTA must be carefully considered.

Watershed and land use-based sources of trace metals in urban storm water.

PubMed

Tiefenthaler, Liesl L; Stein, Eric D; Schiff, Kenneth C

2008-02-01

Trace metal contributions in urban storm water are of concern to environmental managers because of their potential impacts on ambient receiving waters. The mechanisms and processes that influence temporal and spatial patterns of trace metal loading in urban storm water, however, are not well understood. The goals of the present study were to quantify trace metal event mean concentration (EMC), flux, and mass loading associated with storm water runoff from representative land uses; to compare EMC, flux, and mass loading associated with storm water runoff from urban (developed) and nonurban (undeveloped) watersheds; and to investigate within-storm and within-season factors that affect trace metal concentration and flux. To achieve these goals, trace metal concentrations were measured in 315 samples over 11 storm events in five southern California, USA, watersheds representing eight different land use types during the 2000 through 2005 storm seasons. In addition, 377 runoff samples were collected from 12 mass emission sites (end of watershed) during 15 different storm events. Mean flux at land use sites ranged from 24 to 1,238, 0.1 to 1,272, and 6 to 33,189 g/km(2) for total copper, total lead, and total zinc, respectively. Storm water runoff from industrial land use sites contained higher EMCs and generated greater flux of trace metals than other land use types. For all storms sampled, the highest metal concentrations occurred during the early phases of storm water runoff, with peak concentrations usually preceding peak flow. Early season storms produced significantly higher metal flux compared with late season storms at both mass emission and land use sites.

A primer on trace metal-sediment chemistry

USGS Publications Warehouse

Horowitz, Arthur J.

1985-01-01

In most aquatic systems, concentrations of trace metals in suspended sediment and the top few centimeters of bottom sediment are far greater than concentrations of trace metals dissolved in the water column. Consequently, the distribution, transport, and availability of these constituents can not be intelligently evaluated, nor can their environmental impact be determined or predicted solely through the sampling and analysis of dissolved phases. This Primer is designed to acquaint the reader with the basic principles that govern the concentration and distribution of trace metals associated with bottom and suspended sediments. The sampling and analysis of suspended and bottom sediments are very important for monitoring studies, not only because trace metal concentrations associated with them are orders of magnitude higher than in the dissolved phase, but also because of several other factors. Riverine transport of trace metals is dominated by sediment. In addition, bottom sediments serve as a source for suspended sediment and can provide a historical record of chemical conditions. This record will help establish area baseline metal levels against which existing conditions can be compared. Many physical and chemical factors affect a sediment's capacity to collect and concentrate trace metals. The physical factors include grain size, surface area, surface charge, cation exchange capacity, composition, and so forth. Increases in metal concentrations are strongly correlated with decreasing grain size and increasing surface area, surface charge, cation exchange capacity, and increasing concentrations of iron and manganese oxides, organic matter, and clay minerals. Chemical factors are equally important, especially for differentiating between samples having similar bulk chemistries and for inferring or predicting environmental availability. Chemical factors entail phase associations (with such sedimentary components as interstitial water, sulfides, carbonates, and organic matter) and ways in which the metals are entrained by the sediments (such as adsorption, complexation, and within mineral lattices).

Bioaccumulation of trace metals in octocorals depends on age and tissue compartmentalization

PubMed Central

Hwang, Jiang-Shiou; Huang, Ke Li; Huang, Mu-Yeh; Liu, Xue-Jun; Khim, Jong Seong; Wong, Chong Kim

2018-01-01

Trace metal dynamics have not been studied with respect to growth increments in octocorals. It is particularly unknown whether ontogenetic compartmentalization of trace metal accumulation is species-specific. We studied here for the first time the intracolonial distribution and concentrations of 18 trace metals in the octocorals Subergorgia suberosa, Echinogorgia complexa and E. reticulata that were retrieved from the northern coast of Taiwan. Levels of trace metals were considerably elevated in corals collected at these particular coral habitats as a result of diverse anthropogenic inputs. There was a significant difference in the concentration of metals among octocorals except for Sn. Both species of Echinogorgia contained significantly higher concentrations of Cu, Zn and Al than Subergorgia suberosa. We used for the first time exponential growth curves that describe an age-specific relationship of octocoral trace metal concentrations of Cu, Zn, Cd, Cr and Pb where the distance from the grip point was reflecting younger age as linear regressions. The larger colony (C7) had a lower accumulation rate constant than the smaller one (C6) for Cu, Zn, Cd, Cr and Pb, while other trace metals showed an opposite trend. The Cu concentration declined exponentially from the grip point, whereas the concentrations of Zn, Cd, Cr and Pb increased exponentially. In S. suberosa and E. reticulata, Zn occurred primarily in coenosarc tissues and Zn concentrations increased with distance from the grip point in both skeletal and coenosarc tissues. Metals which appeared at high concentrations (e.g. Ca, Zn and Fe) generally tended to accumulate in the outer coenosarc tissues, while metals with low concentrations (e.g. V) tended to accumulate in the soft tissues of the inner skeleton. PMID:29684058

Hydrogeochemical processes governing the origin, transport and fate of major and trace elements from mine wastes and mineralized rock to surface waters

USGS Publications Warehouse

Nordstrom, D. Kirk

2011-01-01

Mobility of potential or actual contaminants from mining and mineral processing activities depends on (1) occurrence: is the mineral source of the contaminant actually present? (2) abundance: is the mineral present in sufficient quantity to make a difference? (3) reactivity: what are the energetics, rates, and mechanisms of sorption and mineral dissolution and precipitation relative to the flow rate of the water? and (4) hydrology: what are the main flow paths for contaminated water? Estimates of relative proportions of minerals dissolved and precipitated can be made with mass-balance calculations if minerals and water compositions along a flow path are known. Combined with discharge, these mass-balance estimates quantify the actual weathering rate of pyrite mineralization in the environment and compare reasonably well with laboratory rates of pyrite oxidation except when large quantities of soluble salts and evaporated mine waters have accumulated underground. Quantitative mineralogy with trace-element compositions can substantially improve the identification of source minerals for specific trace elements through mass balances. Post-dissolution sorption and precipitation (attenuation) reactions depend on the chemical behavior of each element, solution composition and pH, aqueous speciation, temperature, and contact-time with mineral surfaces. For example, little metal attenuation occurs in waters of low pH (2, and redox-sensitive oxyanions (As, Sb, Se, Mo, Cr, V). Once dissolved, metal and metalloid concentrations are strongly affected by redox conditions and pH. Iron is the most reactive because it is rapidly oxidized by bacteria and archaea and Fe(III) hydrolyzes and precipitates at low pH (1–3) which is related directly to its first hydrolysis constant, pK1 = 2.2. Several insoluble sulfate minerals precipitate at low pH including anglesite, barite, jarosite, alunite and basaluminite. Aluminum hydrolyzes near pH 5 (pK1 = 5.0) and provides buffering and removal of Al by mineral precipitation from pH 4–5.5. Dissolved sulfate behaves conservatively because the amount removed from solution by precipitation is usually too small relative to the high concentrations in the water column and relative to the flow rate of the water.

Assessment of mechanisms of metal-induced reproductive toxicity in aquatic species as a biomarker of exposure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, M.; George, W.; Preslan, J.

1996-05-02

This project discusses the following studies: identification and quantitation of heavy metals and petroleum products present in Bayou Trepagnier relative to control sites; assessment of the uptake and bioaccumulation of metals and organic contaminants of interest in aquatic species; establishment and use of polarographic methods for use in metal speciation studies to identify specific chemical forms present in sediments, waters and organism; and evaluation of contaminants on reproductive function of aquatic species as potential biomarkers of exposure. 14 refs.

Culiseta subochrea as a Bioindicator of Metal Contamination in Shadegan International Wetland, Iran (Diptera: Culicidae)

PubMed Central

Nasirian, Hassan; Vazirianzadeh, Babak; Taghi Sadeghi, Sayyed Mohammad; Nazmara, Shahrokh

2014-01-01

Abstract The quantity of some trace metals of mosquito larvae in Shadegan International Wetland from Iran was evaluated. Water, waterbed sediment, and mosquito larvae samplings were carried out from an urban site in the east of the wetland, using standard methods in December 2011. The identified Culiseta subochrea (Edwards) and Aedes caspius s.l. (Pallas) larvae, water, and waterbed sediment samples were analyzed for As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Pb, and Zn trace metals using standard preparation and isolation procedure. Result showed that the waterbed sediment and Cu. subochrea larvae are polluted with all trace metals investigated except As and Hg. The trace metals bioaccumulated in the Cu. subochrea larvae range from 31.78 at the lowest level for Cr to 3822.7 at the highest level for Cd. In a conclusion, this is the first report confirmed that Cu. subochrea likely used as a bioindicator to trace metal pollution in marine ecosystems in the world, especially wetlands. PMID:25550357

Recovery of Trace and Heavy Metals from Coal Combustion Residues for Reuse and Safe Disposal: A Review

NASA Astrophysics Data System (ADS)

Kumar, Ashvani; Samadder, Sukha Ranjan; Elumalai, Suresh Pandian

2016-09-01

The safe disposal of coal combustion residues (CCRs) will remain a major public issue as long as coal is used as a fuel for energy production. Both dry and wet disposal methods of CCRs create serious environmental problems. The dry disposal method creates air pollution initially, and the wet disposal method creates water pollution as a result of the presence of trace and heavy metals. These leached heavy metals from fly ash may become more hazardous when they form toxic compounds such as arsenic sulfite (As2S3) and lead nitrate (N2O6Pb). The available studies on trace and heavy metals present in CCRs cannot ensure environmentally safe utilization. In this work, a novel approach has been offered for the retrieval of trace and heavy metals from CCRs. If the proposed method becomes successful, then the recovered trace and heavy metals may become a resource and environmentally safe use of CCRs may be possible.

Do trace metals (chromium, copper, and nickel) influence toxicity of diesel fuel for free-living marine nematodes?

PubMed

Hedfi, Amor; Boufahja, Fehmi; Ben Ali, Manel; Aïssa, Patricia; Mahmoudi, Ezzeddine; Beyrem, Hamouda

2013-06-01

The objective of this study was to test the hypotheses that (1) free-living marine nematodes respond in a differential way to diesel fuel if it is combined with three trace metals (chromium, copper, and nickel) used as smoke suppressants and that (2) the magnitude of toxicity of diesel fuel differs according to the level of trace metal mixture added. Nematodes from Sidi Salem beach (Tunisia) were subjected separately for 30 days to three doses of diesel fuel and three others of a trace metals mixture. Simultaneously, low-dose diesel was combined with three amounts of a trace metal mixture. Results from univariate and multivariate methods of data evaluation generally support our initial hypothesis that nematode assemblages exhibit various characteristic changes when exposed to different types of disturbances; the low dose of diesel fuel, discernibly non-toxic alone, became toxic when trace metals were added. For all types of treatments, biological disturbance caused severe specific changes in assemblage structure. For diesel fuel-treated microcosms, Marylynnia bellula and Chromaspirinia pontica were the best positive indicative species; their remarkable presence in given ecosystem may predict unsafe seafood. The powerful toxicity of the combination between diesel fuel and trace metals was expressed with only negative bioindicators, namely Trichotheristus mirabilis, Pomponema multipapillatum, Ditlevsenella murmanica, Desmodora longiseta, and Bathylaimus capacosus. Assemblages with high abundances of these species should be an index of healthy seafood. When nematodes were exposed to only trace metals, their response looks special with a distinction of a different list of indicative species; the high presence of seven species (T. mirabilis, P. multipapillatum, Leptonemella aphanothecae, D. murmanica, Viscosia cobbi, Gammanema conicauda, and Viscosia glabra) could indicate a good quality of seafood and that of another species (Oncholaimellus mediterraneus) appeared an index of the opposite situation.

Speciation of Cu and Zn during composting of pig manure amended with rock phosphate.

PubMed

Lu, Duian; Wang, Lixia; Yan, Baixing; Ou, Yang; Guan, Jiunian; Bian, Yu; Zhang, Yubin

2014-08-01

Pig manure usually contains a large amount of metals, especially Cu and Zn, which may limit its land application. Rock phosphate has been shown to be effective for immobilizing toxic metals in toxic metals contaminated soils. The aim of this study work was to investigate the effect of rock phosphate on the speciation of Cu and Zn during co-composting of pig manure with rice straw. The results showed that composting process and rock phosphate addition significantly affected the changes of metal species. During co-composting, the exchangeable and reducible fractions of Cu were transformed to organic and residue fractions, thus the bioavailable Cu fractions were decreased. The rock phosphate addition enhanced the metal transformation depending on the level of rock phosphate amendment. Zinc was found in the exchangeable and reducible fractions in the compost. The bioavailable Zn fraction changed a little during the composting process. The composting process converted the exchangeable Zn fraction into reducible fraction. Addition of an appropriate amount (5.0%) of rock phosphate could advance the conversion. Rock phosphate could reduce metal availability through adsorption and complexation of the metal ions on inorganic components. The increase in pH and organic matter degradation could be responsible for the reduction in exchangeable and bioavailable Cu fractions and exchangeable Zn fraction in rock phosphate amended compost. Copyright © 2014 Elsevier Ltd. All rights reserved.

Assessing time-integrated dissolved concentrations and predicting toxicity of metals during diel cycling in streams

USGS Publications Warehouse

Balistrieri, Laurie S.; Nimick, David A.; Mebane, Christopher A.

2012-01-01

Evaluating water quality and the health of aquatic organisms is challenging in systems with systematic diel (24 hour) or less predictable runoff-induced changes in water composition. To advance our understanding of how to evaluate environmental health in these dynamic systems, field studies of diel cycling were conducted in two streams (Silver Bow Creek and High Ore Creek) affected by historical mining activities in southwestern Montana. A combination of sampling and modeling tools were used to assess the toxicity of metals in these systems. Diffusive Gradients in Thin Films (DGT) samplers were deployed at multiple time intervals during diel sampling to confirm that DGT integrates time-varying concentrations of dissolved metals. Thermodynamic speciation calculations using site specific water compositions, including time-integrated dissolved metal concentrations determined from DGT, and a competitive, multiple-metal biotic ligand model incorporated into the Windemere Humic Aqueous Model Version 6.0 (WHAM VI) were used to determine the chemical speciation of dissolved metals and biotic ligands. The model results were combined with previously collected toxicity data on cutthroat trout to derive a relationship that predicts the relative survivability of these fish at a given site. This integrative approach may prove useful for assessing water quality and toxicity of metals to aquatic organisms in dynamic systems and evaluating whether potential changes in environmental health of aquatic systems are due to anthropogenic activities or natural variability.

Ce, Ti modified MCM-48 mesoporous photocatalysts: Effect of the synthesis route on support and metal ion properties

NASA Astrophysics Data System (ADS)

Mureseanu, Mihaela; Filip, Mihaela; Somacescu, Simona; Baran, Adriana; Carja, Gabriela; Parvulescu, Viorica

2018-06-01

New Ti-MCM-48 and CeTi-MCM-48 photocatalysts were obtained by impregnation of the MCM-48 silica support synthesized by a hydrothermal process with aqueous solution of Ti and Ce precursors. The immobilization of metal cations presented a low effect on the porosity, morphology and structure of MCM-48 mesoporous silica support as was evidenced by N2 adsorption-desorption, X-ray diffraction, SEM and TEM electron microscopy. EDAX analysis and X-ray photoelectron microscopy (XPS) indicated that titanium cations were present on the mesoporous silica surface only as Ti4+ species and the effect of ceria on titanium speciation was different, compared to the CeTi-MCM-48 sample, previously obtained by direct synthesis. The photocatalytic properties of mono- and bimetallic catalysts were evaluated in degradation of phenol from water and correlated with the active metallic species concentration, distribution, speciation and their interaction with the support or each other. An advanced oxidation mechanism for phenol degradation by radical species was proposed.

Arsenic speciation and heavy metal distribution in polished rice grown in Guangdong Province, Southern China.

PubMed

Ma, Li; Wang, Lin; Tang, Jie; Yang, Zhaoguang

2017-10-15

Arsenic speciation and heavy metal distributions have been investigated in locally grown rice grains from Guangdong Province, Southern China. A total of 41 polished rice grain samples were collected throughout Guangdong Province. Arsenite (As(III)), as the predominant form found in the rice, was positively correlated (p<0.01) with total As (tAs) concentration. However, the percentage of As(III) reduced while tAs concentration increased (r=-0.361, p<0.05), due to restricted accumulation and translocation of As(III) in rice grains at high level of tAs. Statistical and geostatistical analyses were applied to investigate potential origins of heavy metals in rice. Only Cd, Cu and Ni were identified as influenced by anthropogenic sources such as industrial and commercial activities. As and Pb were primarily controlled by natural occurrence. The results of health risk assessment implied that continuous intake of rice grown in Guangdong Province could cause considerably non-carcinogenic and carcinogenic risk to local inhabitants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Assessment of acid leachable trace metals in sediment cores from River Uppanar, Cuddalore, Southeast coast of India.

PubMed

Ayyamperumal, T; Jonathan, M P; Srinivasalu, S; Armstrong-Altrin, J S; Ram-Mohan, V

2006-09-01

An acid leachable technique is employed in core samples (C1, C2 and C3) to develop a baseline data on the sediment quality for trace metals of River Uppanar, Cuddalore, southeast coast of India. Acid leachable metals (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn and Cd) indicate peak values at the sulphidic phase and enrichment of metals in the surface layers are due to the anthropogenic activities. Association of trace metals with Fe, Mn indicates their adsorption onto Fe-Mn oxyhydroxides and their correlation with S indicate that they are precipitated as metal sulphides. Factor analysis identified three possible types of geochemical associations and the supremacy of trace metals along with Fe, Mn, S and mud supports their geochemical associations. Factor analysis also signifies that anthropogenic activities have affected both the estuarine and fresh water regions of River Uppanar.

Water-quality data for the Clark Fork and selected tributaries from Deer Lodge to Milltown, Montana, March 1985 through June 1986

USGS Publications Warehouse

Lambing, J.H.

1987-01-01

A sampling program was conducted at six stream sites. The purpose of the study was to collect baseline data on concentrations of suspended sediment and selected trace metals in streamflow. Included in this report are tables of daily data for mean streamflow, suspended sediment concentration, and suspended sediment discharge at two streamflow gaging stations on the Clark Fork; periodic data for instantaneous streamflow, onsite water quality, and trace metal and suspended sediment concentrations in the Clark Fork and tributaries; and summary statistics for all the water quality data. Also included are graphs for each site showing median concentrations of trace metals, relationship of concentrations of trace metals to suspended sediment, and median concentrations of trace metals in suspended sediments. Hydrographs for two sites on the main stem show daily mean streamflow, suspended sediment concentration, and suspended sediment discharge for the period of study. (Author 's abstract)

Consumer-producer relationships for trace metals in Chorthippus brunneus (Thunberg. )

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, M.S.

1986-08-01

The behavior of trace metals in terrestrial food chains is a subject of ecological interest, particularly in polluted environments where the potential exists for bioconcentration of metals known to be essential in trace amounts for normal plant and animal metabolism, as well as those with no known metabolic function but recognized toxicological properties. Laboratory studies of food chain relationships afford a means by which direct comparisons can be made between trace metals as a basis for interpretation of data collected from wild plant and animal populations. This study compares the behavior of three trace elements, copper, zinc and cadmium, inmore » terms of their assimilation under experimental conditions by the herbivorous common field grasshopper, Chorthippus brunneus (Thunberg.). This voracious orthopteran is widely distributed in Britain and is particularly prominent in the restricted invertebrate community of some metal smelter-affected grasslands where it forms important seasonal prey for insectivorous small mammals.« less

Chemodynamics of heavy metals in long-term contaminated soils: metal speciation in soil solution.

PubMed

Kim, Kwon-Rae; Owens, Gary

2009-01-01

The concentration and speciation of heavy metals in soil solution isolated from long-term contaminated soils were investigated. The soil solution was extracted at 70% maximum water holding capacity (MWHC) after equilibration for 24 h. The free metal concentrations (Cd2+, CU2+, Pb2+, and Zn2+) in soil solution were determined using the Donnan membrane technique (DMT). Initially the DMT was validated using artificial solutions where the percentage of free metal ions were significantly correlated with the percentages predicted using MINTEQA2. However, there was a significant difference between the absolute free ion concentrations predicted by MINTEQA2 and the values determined by the DMT. This was due to the significant metal adsorption onto the cation exchange membrane used in the DMT with 20%, 28%, 44%, and 8% mass loss of the initial total concentration of Cd, Cu, Pb, and Zn in solution, respectively. This could result in a significant error in the determination of free metal ions when using DMT if no allowance for membrane cation adsorption was made. Relative to the total soluble metal concentrations the amounts of free Cd2+ (3%-52%) and Zn2+ (11%-72%) in soil solutions were generally higher than those of Cu2+ (0.2%-30%) and Pb2+ (0.6%-10%). Among the key soil solution properties, dissolved heavy metal concentrations were the most significant factor governing free metal ion concentrations. Soil solution pH showed only a weak relationship with free metal ion partitioning coefficients (K(p)) and dissolved organic carbon did not show any significant influence on K(p).

The transport behavior of As, Cu, Pb, and Zn during electrokinetic remediation of a contaminated soil using electrolyte conditioning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Jung-Seok; Kwon, Man Jae; Choi, Jaeyoung

2014-12-01

Electrokinetic remediation (also known as electrokinetics) is a promising technology for removing metals from fine-grained soils. However, few studies have been conducted regarding the transport behavior of multi-metals during electrokinetics. We investigated the transport of As, Cu, Pb, and Zn from soils during electrokinetics, the metal fractionation before and after electrokinetics, the relationships between metal transport and fractionation, and the effects of electrolyte conditioning. The main transport mechanisms of the metals were electroosmosis and electromigration during the first two weeks and electromigration during the following weeks. The direction of electroosmotic flow was from the anode to the cathode, and themore » metals in the dissolved and reducible-oxides fractions were transported to the anode or cathode by electromigration according to the chemical speciation of the metal ions in the pore water. Moreover, a portion of the metals that were initially in the residual fraction transitioned to the reducible and soluble fractions during electrokinetic treatment. However, this alteration was slow and resulted in decreasing metal removal rates as the electrokinetic treatment progressed. In addition, the use of NaOH, H3PO4, and Na2SO4 as electrolytes resulted in conditions that favored the precipitation of metal hydroxides, phosphates, and sulfates in the soil. These results demonstrated that metal removal was affected by the initial metal fractionation, metal speciation in the pore solution, and the physical–chemical parameters of the electrolytes, such as pH and electrolyte composition. Therefore, the treatment time, use of chemicals, and energy consumption could be reduced by optimizing pretreatment and by choosing appropriate electrolytes for the target metals.« less

Distribution of trace metals in the vicinity of a wastewater treatment plant on the Potomac River, Washington, DC, USA

NASA Astrophysics Data System (ADS)

Smith, J. P.; Muller, A. C.

2013-05-01

Predicting the fate and distribution of anthropogenic-sourced trace metals in riverine and estuarine systems is challenging due to multiple and varying source functions and dynamic physiochemical conditions. Between July 2011 and November 2012, sediment and water column samples were collected from over 20 sites in the tidal-fresh Potomac River estuary, Washington, DC near the outfall of the Blue Plains Advanced Wastewater Treatment Plant (BPWTP) for measurement of select trace metals. Field observations of water column parameters (conductivity, temperature, pH, turbidity) were also made at each sampling site. Trace metal concentrations were normalized to the "background" composition of the river determined from control sites in order to investigate the distribution BPWTP-sourced in local Potomac River receiving waters. Temporal differences in the observed distribution of trace metals were attributed to changes in the relative contribution of metals from different sources (wastewater, riverine, other) coupled with differences in the physiochemical conditions of the water column. Results show that normalizing near-source concentrations to the background composition of the water body and also to key environmental parameters can aid in predicting the fate and distribution of anthropogenic-sourced trace metals in dynamic riverine and estuarine systems like the tidal-fresh Potomac River.

Trace elements in feathers and eggshells of brown booby Sula leucogaster in the Marine National Park of Currais Islands, Brazil.

PubMed

Dolci, Natiely Natalyane; Sá, Fabian; da Costa Machado, Eunice; Krul, Ricardo; Rodrigues Neto, Renato

2017-09-10

Levels of trace elements were investigated in feathers of 51 adults and 47 eggshells of brown boobies Sula leucogaster from one bird colony in the Marine National Park of Currais Islands, Brazil, between December 2013 and October 2014. Average concentrations (μg g -1 , dry weight) in feathers and eggshells, respectively, were Al 50.62-9.58, As 0.35-2.37, Cd 0.05-0.03, Co 0.38-2.1, Cu 15.12-0.99, Fe 47.47-22.92, Mg 815.71-1116.92, Ni 0.29-11.85, and Zn 94.16-1.98. In both arrays, the average concentration of Mg was the highest among all the elements analyzed, while the lowest was recorded for Cd. As and Ni presented levels at which biological impacts might occur. Zn concentrations were higher than those considered normal in other organs. Levels of Al, Fe, Cu, Zn, and Cd were higher in feathers, whereas higher contents of Mg, Co, Ni, and As occurred in eggshells. The comparison between the elements in eggshells collected at different seasons showed no significant difference (p > 0.05) due, probably, to the lack of temporal variation on foraging behavior and/or on bioavailability of trace elements. Metals and arsenic in feathers and eggshells were mostly not correlated. Future studies on Paraná coast should focus on the speciation of the elements, especially As, Ni, and Zn, which proved to be a possible problem for the environment and biota. It is necessary to investigate both matrices, shell and internal contents of the eggs, in order to verify if the differences previously reported in other studies also occur in eggs of brown boobies in the Marine National Park of Currais Islands.

Content of trace elements and chromium speciation in Neem powder and tea infusions.

PubMed

Novotnik, Breda; Zuliani, Tea; Ščančar, Janez; Milačič, Radmila

2015-01-01

Total concentrations of selected trace elements in Neem powder and in Neem tea were determined by inductively coupled plasma mass spectrometry (ICP-MS). The data revealed that despite high total concentrations of the potentially toxic elements Al and Ni in Neem powder, their amounts dissolved in Neem tea were low. Total concentrations of the other toxic elements Pb, As and Cd were also very low and do not represent a health hazard. In contrast, total concentrations of the essential elements Fe, Cu, Zn, Se Mo and Cr in Neem powder were high and also considerable in Neem tea. Consuming one cup of Neem tea (2g per 200 mL of water) covers the recommended daily intakes for Cr and Se and represents an important source of Mo and Cu. Speciation analysis of Cr by high performance liquid chromatography (HPLC) coupled to ICP-MS with the use of enriched Cr isotopic tracers to follow species interconversions during the analytical procedure demonstrated that toxic Cr(VI) was not present either in Neem powder or in Neem tea. Its concentrations were below the limits of detection of the HPLC-ICP-MS procedure applied. The speciation analysis data confirmed that even Cr(VI) was added, it was rapidly reduced by the presence of antioxidants in Neem leaves. By the use of enriched Cr isotopic spike solutions it was also demonstrated that for obtaining reliable analytical data it is essential to apply the extraction procedures which prevent Cr species interconversions, or to correct for species transformation. Copyright © 2015 Elsevier GmbH. All rights reserved.

Trophic transfer of trace metals from the polychaete worm Nereis diversicolor to the polychaete N. virens and the decapod crustacean Palaemonetes varians

USGS Publications Warehouse

Rainbow, P.S.; Poirier, L.; Smith, B.D.; Brix, K.V.; Luoma, S.N.

2006-01-01

Diet is an important exposure route for the uptake of trace metals by aquatic invertebrates, with trace metal trophic transfer depending on 2 stages - assimilation and subsequent accumulation by the predator. This study investigated the trophic transfer of trace metals from the sediment-dwelling polychaete worm Nereis diversicolor from metal-rich estuarine sediments in southwestern UK to 2 predators - another polychaete N. virens (Cu, Zn, Pb, Cd, Fe) and the decapod crustacean Palaemonetes varians (Cu, Zn, Pb, Cd, Fe, Ag, As, Mn). N. virens showed net accumulation of Cu, Zn, Pb and Cd from the prey; accumulation increased with increasing prey concentration, but a coefficient of trophic transfer decreased with increasing prey concentration, probably because a higher proportion of accumulated metal in the prey is bound in less trophically available (insoluble) detoxified forms. The trace metal accumulation patterns of P. varians apparently restricted significant net accumulation of metals from the diet of N. diversicolor to just Cd. There was significant mortality of the decapods fed on the diets of metal-rich worms. Metal-rich invertebrates that have accumulated metals from the rich historical store in the sediments of particular SW England estuaries can potentially pass these metals along food chains, with accumulation and total food chain transfer depending on the metal assimilation efficiencies and accumulation patterns of the animal at each trophic level. This trophic transfer may be significant enough to have ecotoxicological effects. ?? Inter-Research 2006.

Trace-metal and organic constituent concentrations in bed sediment at Big Base and Little Base Lakes, Little Rock Air Force Base, Arkansas—Comparisons to sediment-quality guidelines and indications for timing of exposure

USGS Publications Warehouse

Justus, B.G.; Hays, Phillip D.; Hart, Rheannon M.

2015-09-16

Regarding highest concentrations and associated timing of exposure, trace metals analyzed in the sediment core seem to indicate three fairly distinct exposure patterns. For 11 trace metals that had the highest concentration measured in the shallowest and most recently deposited sediment, the most likely explanation is recent exposure by anthropogenic activities. Most of the 11 trace metals with highest concentrations in shallow sediment are relatively innocuous; however, arsenic, copper, selenium, and zinc are among the U.S. Environmental Protection Agency’s 126 priority pollutants. For three trace metals (cadmium, lead, and mercury), for which concentrations were highest in sediments that were 16–20 centimeters down the core, it is likely that a source associated with those contaminants during the period when those sediments were deposited, was reduced or eliminated. The eight remaining trace metals, for which concentrations were highest in sediments that were just below the prereservoir surface, likely had sources that were eliminated soon after lake construction or occurred at relatively high background concentrations in soils in the area around Little Rock Air Force Base.

Automation of liquid-liquid extraction-spectrophotometry using prolonged pseudo-liquid drops and handheld CCD for speciation of Cr(VI) and Cr(III) in water samples.

PubMed

Chen, Wen; Zhong, Guanping; Zhou, Zaide; Wu, Peng; Hou, Xiandeng

2005-10-01

A simple spectrophotometric system, based on a prolonged pseudo-liquid drop device as an optical cell and a handheld charge coupled device (CCD) as a detector, was constructed for automatic liquid-liquid extraction and spectrophotometric speciation of trace Cr(VI) and Cr(III) in water samples. A tungsten halogen lamp was used as the light source, and a laboratory-constructed T-tube with two open ends was used to form the prolonged pseudo-liquid drop inside the tube. In the medium of perchloric acid solution, Cr(VI) reacted with 1,5-diphenylcarbazide (DPC); the formed complex was automatically extracted into n-pentanol, with a preconcentration ratio of about 5. The organic phase with extracted chromium complex was then pumped through the optical cell for absorbance measurement at 548 nm. Under optimal conditions, the calibration curve was linear in the range of 7.5 - 350 microg L(-1), with a correlation coefficient of 0.9993. The limit of detection (3sigma) was 7.5 microg L(-1). That Cr(III) species cannot react with DPC, but can be oxidized to Cr(VI) prior to determination, is the basis of the speciation analysis. The proposed speciation analysis was sensitive, yet simple, labor-effective, and cost-effective. It has been preliminarily applied for the speciation of Cr(VI) and Cr(III) in spiked river and tap water samples. It can also be used for other automatic liquid-liquid extraction-spectrophotometric determinations.

Understanding how cells allocate metals using metal sensors and metallochaperones.

PubMed

Tottey, Stephen; Harvie, Duncan R; Robinson, Nigel J

2005-10-01

Each metalloprotein must somehow acquire the correct metal. We review the insights into metal specificity in cells provided by studies of ArsR-SmtB DNA binding, metal-responsive transcriptional repressors, and a bacterial copper chaperone. Cyanobacteria are the one bacterial group that have known enzymatic demand for cytoplasmic copper import. The copper chaperone and ATPases that supply cyanobacterial plastocyanin and cytochrome oxidase are reviewed, along with related ATPases for cobalt and zinc. These studies highlight the contributions of protein-protein interactions to metal speciation. Metal sensors and metallochaperones, along with metal transporters and metal-storage proteins, act in concert not only to supply the correct metals but also to withhold the wrong ones.

Spatial distribution of trace metals in the Krka River, Croatia: an example of the self-purification.

PubMed

Cukrov, Neven; Cmuk, Petra; Mlakar, Marina; Omanović, Dario

2008-08-01

The spatial distribution of dissolved and total trace metals (Zn, Cd, Pb and Cu) in the Krka River (partly located in the Krka National Park) has been studied using a "clean" sampling, handling and analysis technique. Differential pulse anodic stripping voltammetry (DPASV) with a hanging mercury drop electrode (HMDE) has been used for trace metal analysis. The Krka River has been divided into the upper and lower flow region with respect to the metals concentration and main physico-chemical parameters. A significant increase in trace metal concentration as the result of the untreated waste water discharge downstream of Knin Town has been registered in the upper flow region. Due to a specific characteristic of the Krka, the so-called self-purification process, a decrease in the elevated trace metals concentration from the water column takes place at numerous small lakes formed by tufa barriers (at the end of the upper flow region). The clean groundwater input at the beginning of the lower flow region additionally contributes to the observed decrease in trace metals concentration in the Krka, maintaining them at a very low level in the remaining region of fresh-water flow. The determined median total concentrations were zinc 120-7400 ng l(-1), cadmium 3-8 ng l(-1), lead 11-250 ng l(-1) and copper 110-440 ng l(-1). Karst rivers, such as the Krka River, with extremely low natural concentrations of trace metals are highly sensitive to the anthropogenic influence. Therefore, such aquatic systems require implementation of strict protection regimes in the entire catchments area.

Determining the speciation of Zn in soils around the sediment ponds of chemical plants by XRD and XAFS spectroscopy and sequential extraction.

PubMed

Minkina, Tatiana; Nevidomskaya, Dina; Bauer, Tatiana; Shuvaeva, Victoria; Soldatov, Alexander; Mandzhieva, Saglara; Zubavichus, Yan; Trigub, Alexander

2018-09-01

For a correct assessment of risk of polluted soil, it is crucial to establish the speciation and mobility of the contaminants. The aim of this study was to investigate the speciation and transformation of Zn in strongly technogenically transformed contaminated Spolic Technosols for a long time in territory of sludge collectors by combining analytical techniques and synchrotron techniques. Sequential fractionation of Zn compounds in studied soils revealed increasing metal mobility. Phyllosilicates and Fe and Mn hydroxides were the main stabilizers of Zn mobility. A high degree of transformation was identified for the composition of the mineral phase in Spolic Technosols by X-ray powder diffraction. Technogenic phases (Zn-containing authigenic minerals) were revealed in Spolic Technosols samples through the analysis of their Zn K-edge EXAFS and XANES spectra. In one of the samples Zn local environment was formed by predominantly oxygen atoms, and in the other one mixed ZnS and ZnO bonding was found. Zn speciation in the studied technogenically transformed soils was due to the composition of pollutants contaminating the floodplain landscapes for a long time, and, second, this is the combination of physicochemical properties controlling the buffer properties of investigated soils. X-ray spectroscopic and X-ray powder diffraction analyses combined with sequential extraction assays is an effective tool to check the affinity of the soil components for heavy metal cations. Copyright © 2018 Elsevier B.V. All rights reserved.

Heavy metal speciation in various grain sizes of industrially contaminated street dust using multivariate statistical analysis.

PubMed

Yıldırım, Gülşen; Tokalıoğlu, Şerife

2016-02-01

A total of 36 street dust samples were collected from the streets of the Organised Industrial District in Kayseri, Turkey. This region includes a total of 818 work places in various industrial areas. The modified BCR (the European Community Bureau of Reference) sequential extraction procedure was applied to evaluate the mobility and bioavailability of trace elements (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in street dusts of the study area. The BCR was classified into three steps: water/acid soluble fraction, reducible and oxidisable fraction. The remaining residue was dissolved by using aqua regia. The concentrations of the metals in street dust samples were determined by flame atomic absorption spectrometry. Also the effect of the different grain sizes (<38µm, 38-53µm and 53-74µm) of the 36 street dust samples on the mobility of the metals was investigated using the modified BCR procedure. The mobility sequence based on the sum of the first three phases (for <74µm grain size) was: Cd (71.3)>Cu (48.9)>Pb (42.8)=Cr (42.1)>Ni (41.4)>Zn (40.9)>Co (36.6)=Mn (36.3)>Fe (3.1). No significant difference was observed among metal partitioning for the three particle sizes. Correlation, principal component and cluster analysis were applied to identify probable natural and anthropogenic sources in the region. The principal component analysis results showed that this industrial district was influenced by traffic, industrial activities, air-borne emissions and natural sources. The accuracy of the results was checked by analysis of both the BCR-701 certified reference material and by recovery studies in street dust samples. Copyright © 2015 Elsevier Inc. All rights reserved.

Uptake of elements from seawater by ferromanganese crusts: Solid-phase associations and seawater speciation

USGS Publications Warehouse

Koschinsky, A.; Hein, J.R.

2003-01-01

Marine Fe-Mn oxyhydroxide crusts form by precipitation of dissolved components from seawater. Three hydrogenetic crust samples (one phosphatized) and two hydrothermal Mn-oxide samples were subjected to a sequential-leaching procedure in order to determine the host phases of 40 elements. Those host-phase associations are discussed with respect to element speciation in seawater. The partitioning of elements between the two major phases, Mn oxide and Fe oxyhydroxide, can in a first-order approximation be explained by a simple sorption model related to the inorganic speciation of the elements in seawater, as has been proposed in earlier models. Free and weakly complexed cations, such as alkali and alkaline earth metals, Mn, Co, Ni, Zn, T1(I), and partly Y, are sorbed preferentially on the negatively charged surface of the MnO2 in hydrogenetic crusts. The driving force is a strong coulombic interaction. All neutral or negatively charged chloro (Cd, Hg, T1), carbonate (Cu, Y, Pb, and U), and hydroxide (Be, Sc, Ti, Fe, Zr, Nb, In, Sn, Sb, Te, Hf, Ta, Bi, Th, and T1(III)) complexes and oxyanions (V, Cr, As, Se, Mo, and W) bind to the slightly positively charged surface of the amorphous FeOOH phase. While coulombic interaction can explain the sorption of the negatively charged species, the binding of neutral species is based on specific chemical interaction. Organic complexation of elements in deep-ocean water seems to be at most of minor importance. Surface oxidation can explain some strong metal associations, e.g. of Co and T1 with the MnO2 and Te with the FeOOH. Sorption reactions initially driven by coulombic forces are often followed by the formation of specific bonds between the adsorbate and the atoms of the oxide surface. Differences in the associations of some metals between the non-phosphatized and phosphatized hydrogenetic crusts and between the hydrogenetic and the hydrothermal samples reflect the different physico-chemical environments of formation and speciations in oxic seawater vs. less-oxic fluids, especially for the redox-sensitive metals such as Mo and V. These environmental-related differences indicate that the methodology of chemical speciation used here in combination with spectroscopic methods may allow for the detection of changes in paleoceanographic conditions recorded during the several tens of millions of years of crust growth. ?? 2003 Elsevier Science B.V. All rights reserved.

Soft X-ray spectromicroscopy for speciation, quantitation and nano-eco-toxicology of nanomaterials.

PubMed

Lawrence, J R; Swerhone, G D W; Dynes, J J; Korber, D R; Hitchcock, A P

2016-02-01

There is a critical need for methods that provide simultaneous detection, identification, quantitation and visualization of nanomaterials at their interface with biological and environmental systems. The approach should allow speciation as well as elemental analysis. Using the intrinsic X-ray absorption properties, soft X-ray scanning transmission X-ray spectromicroscopy (STXM) allows characterization and imaging of a broad range of nanomaterials, including metals, oxides and organic materials, and at the same time is able to provide detailed mapping of biological components. Thus, STXM offers considerable potential for application to research on nanomaterials in biology and the environment. The potential and limitations of STXM in this context are discussed using a range of examples, focusing on the interaction of nanomaterials with microbial cells, biofilms and extracellular polymers. The studies outlined include speciation and mapping of metal-containing nanomaterials (Ti, Ni, Cu) and carbon-based nanomaterials (multiwalled carbon nanotubes, C60 fullerene). The benefits of X-ray fluorescence detection in soft X-ray STXM are illustrated with a study of low levels of Ni in a natural river biofilm. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

[Impact of acid mining drainage on the quality of superficial waters and sediments in the Marrakesh region, Morocco].

PubMed

El Gharmali, A; Rada, A; El Adnani, M; Tahlil, N; El Meray, M; Nejmeddine, A

2004-12-01

The aim of the present study is the evaluation of the effects of the acid drainage of three abandoned mining sites: SB-Othmane, Kettara and Draâ-sfar, on water and sediment quality of the Tensift River and its two temporary tributaries, the Kettara and El-Coudia Oueds. These mining sites located near Marrakesh contain mining residues abandoned for ten to twenty years. They are presently in an agricultural region of the Haouz district. In each site, these uncontrolled mining residues present a high level of metallic sulphide and generate, during rainy periods, leaching products which have physical and chemical characteristics of acid mine drainage (AMD). These percolates display an acidic pH ranging from 2.5 to 5.2, a high electric conductivity, large amounts of sulphate and heavy metals, especially under dissolved form (e.g. Cd: 17.34 mg l(-1); Fe: 1734 mg l(-1); Zn: 3935 mg l(-1)). Except for Pb, the free ionic form is the most abundant metallic form, as showed by calculations using the speciation GEOCHEM program. The analysis of water and sediments of the surrounding superficial aquatic ecosystems shows a modification of water chemical facies and an enrichment in heavy metals, mainly under the solid phase for Fe, Pb, Cu, Co, Cr and Ni, and under dissolved fraction for Cd and Zn. The dissolved fraction of these metals is dominated by the free ionic form, considered as available for organisms. Furthermore, sediments contain important quantities of heavy metals (Pb: 1450 microg g(-1), Zn: 1562 microg g(-1)) with an available fraction which is higher than 40% for the Cd and Zn. The abundance of trace elements (free ionic and available forms) in water and sediment presents a durable risk of their transfer to food chains.

Route and Regulation of Zinc, Cadmium, and Iron Transport in Rice Plants (Oryza sativa L.) during Vegetative Growth and Grain Filling: Metal Transporters, Metal Speciation, Grain Cd Reduction and Zn and Fe Biofortification

PubMed Central

Yoneyama, Tadakatsu; Ishikawa, Satoru; Fujimaki, Shu

2015-01-01

Zinc (Zn) and iron (Fe) are essential but are sometimes deficient in humans, while cadmium (Cd) is toxic if it accumulates in the liver and kidneys at high levels. All three are contained in the grains of rice, a staple cereal. Zn and Fe concentrations in rice grains harvested under different levels of soil/hydroponic metals are known to change only within a small range, while Cd concentrations show greater changes. To clarify the mechanisms underlying such different metal contents, we synthesized information on the routes of metal transport and accumulation in rice plants by examining metal speciation, metal transporters, and the xylem-to-phloem transport system. At grain-filling, Zn and Cd ascending in xylem sap are transferred to the phloem by the xylem-to-phloem transport system operating at stem nodes. Grain Fe is largely derived from the leaves by remobilization. Zn and Fe concentrations in phloem-sap and grains are regulated within a small range, while Cd concentrations vary depending on xylem supply. Transgenic techniques to increase concentrations of the metal chelators (nicotianamine, 2′-deoxymugineic acid) are useful in increasing grain Zn and Fe concentrations. The elimination of OsNRAMP5 Cd-uptake transporter and the enhancement of root cell vacuolar Cd sequestration reduce uptake and root-to-shoot transport, respectively, resulting in a reduction of grain Cd accumulation. PMID:26287170

Speciation of Cu and Zn in drainage water from agricultural soils.

PubMed

Aldrich, Annette P; Kistler, David; Sigg, Laura

2002-11-15

Inputs of copper and zinc from agricultural soils into the aquatic system were investigated in this study, because of their heavy agricultural usage as feed additives and components of fertilizers and fungicides. As the mobility and bioavailability of these metals are affected by their speciation, the lipophilic, colloidal and organic fractions were determined in drainage water from a loamy and a humic soil treated with fungicides or manure. This study therefore investigates the impact of agricultural activity on a natural environment and furthers our understanding of the mobility of metals in agricultural soils and aquatic pollution in rural areas. Marked increases in the total dissolved metal concentrations were observed in the drainage water during rain events with up to 0.3 microM Cu and 0.26 microM Zn depending on the intensity of the rainfall and soil type. The mobile metal fractions were of a small molecular size (<10 kD) and mainly hydrophilic. Lipophilic complexes originating from a dithiocarbamate (DTC) fungicide could not be observed in the drainage water; however, small amounts of lipophilic metal complexes may be of natural origin. Cu was organically complexed to > 99.9% by abundant organic ligands (log K 10.5-11.0). About 50% of dissolved Zn were electrochemically labile, and the other 50% were complexed by strong organic ligands (log K 8.2-8.6). Therefore very little free metal species were found suggesting a low bioavailability of these metals in the drainage water even at elevated metal concentrations.

Route and Regulation of Zinc, Cadmium, and Iron Transport in Rice Plants (Oryza sativa L.) during Vegetative Growth and Grain Filling: Metal Transporters, Metal Speciation, Grain Cd Reduction and Zn and Fe Biofortification.

PubMed

Yoneyama, Tadakatsu; Ishikawa, Satoru; Fujimaki, Shu

2015-08-13

Zinc (Zn) and iron (Fe) are essential but are sometimes deficient in humans, while cadmium (Cd) is toxic if it accumulates in the liver and kidneys at high levels. All three are contained in the grains of rice, a staple cereal. Zn and Fe concentrations in rice grains harvested under different levels of soil/hydroponic metals are known to change only within a small range, while Cd concentrations show greater changes. To clarify the mechanisms underlying such different metal contents, we synthesized information on the routes of metal transport and accumulation in rice plants by examining metal speciation, metal transporters, and the xylem-to-phloem transport system. At grain-filling, Zn and Cd ascending in xylem sap are transferred to the phloem by the xylem-to-phloem transport system operating at stem nodes. Grain Fe is largely derived from the leaves by remobilization. Zn and Fe concentrations in phloem-sap and grains are regulated within a small range, while Cd concentrations vary depending on xylem supply. Transgenic techniques to increase concentrations of the metal chelators (nicotianamine, 2'-deoxymugineic acid) are useful in increasing grain Zn and Fe concentrations. The elimination of OsNRAMP5 Cd-uptake transporter and the enhancement of root cell vacuolar Cd sequestration reduce uptake and root-to-shoot transport, respectively, resulting in a reduction of grain Cd accumulation.

Inert Reassessment Document for Ethylenediaminetetracetric acid (EDTA)

EPA Pesticide Factsheets

EDTA is a chelating agent. Its ability to bind heavy metal ions can be used to sequester these trace metals. However, trace amounts of various metals are necessary for the proper functioning of the body.

Emissions of trace gases and aerosols during the open combustion of biomass in the laboratory

Treesearch

Gavin R. McMeeking; Sonia M. Kreidenweis; Stephen Baker; Christian M. Carrico; Judith C. Chow; Jeffrey L. Collett; Wei Min Hao; Amanda S. Holden; Thomas W. Kirchstetter; William C. Malm; Hans Moosmuller; Amy P. Sullivan; Cyle E. Wold

2009-01-01

We characterized the gas- and speciated aerosol-phase emissions from the open combustion of 33 different plant species during a series of 255 controlled laboratory burns during the Fire Laboratory at Missoula Experiments (FLAME). The plant species we tested were chosen to improve the existing database for U.S. domestic fuels: laboratory-based emission...

Reconnaissance for trace metals in bed sediment, Wright Patman Lake, near Texarkana, Texas

USGS Publications Warehouse

McKee, Paul W.

2001-01-01

Many contaminants can be introduced into the environment by urban and industrial activities. The drainage area of Wright Patman Lake is influenced by these activities. Among the contaminants associated with urban and industrial activities are trace metals such as arsenic, lead, mercury, and zinc. These contaminants are relatively insoluble in water and commonly are found in stream, lake, and reservoir bottom sediment, especially the clays and silts within the sediment.Wright Patman Lake serves as the major potable water supply for the city of Texarkana and surrounding communities. Texarkana, located in the northeastern corner of Texas and the southwestern corner of Arkansas, had a population of about 56,000 in 1998, which reflects an increase of about 3.4 percent from the 1990 census (Ramos, 1999). Texarkana Water Utilities, which manages the water-treatment facilities for Texarkana, proposes to dredge the lake bed near the water intake in the Elliot Creek arm of Wright Patman Lake. It is possible that arsenic, lead, mercury, and other trace metals might be released into the water if the bed sediment is disturbed. Bed sediment in the Elliot Creek arm of the lake, in particular, could contain trace metals because of its proximity to Red River Army Depot and because industrial land use is prevalent in the headwaters of Elliot Creek.The U.S. Geological Survey (USGS), in cooperation with Reconnaissance for Trace Metals in Bed Sediment, Wright Patman Lake, Near Texarkana, Texas In cooperation with the Texarkana Water Utilities conducted a reconnaissance of Wright Patman Lake to collect bed-sediment samples for analysis of trace metals. This report presents trace metal concentrations in bed-sediment samples collected at six sites along the Elliot Creek arm of the lake, one site each in two adjacent arms, and one site near the dam on June 16, 1999 (fig. 1). One bed-sediment sample was collected at each of the nine sites, and one sediment core was collected at each of two of the sites. Trace metal concentrations are compared to sediment-quality guidelines for the protection of aquatic life and to screening levels based on historical trace metal concentrations in bed sediment of Texas reservoirs.

Geochemical Weathering Increases Lead Bioaccessibility in Semi-Arid Mine Tailings

PubMed Central

Hayes, Sarah M.; Webb, Sam M.; Bargar, John R.; O'Day, Peggy A.; Maier, Raina M.; Chorover, Jon

2012-01-01

Mine tailings can host elevated concentrations of toxic metal(loid)s that represent a significant hazard to surrounding communities and ecosystems. Eolian transport, capable of translocating small (micrometer-sized) particles, can be the dominant mechanism of toxic metal dispersion in arid or semi-arid landscapes. Human exposure to metals can then occur via direct inhalation or ingestion of particulates. The fact that measured doses of total lead (Pb) in geomedia correlate poorly with blood Pb levels highlights a need to better resolve the precise distribution of molecularly-speciated metal-bearing phases in the complex particle mixtures. Species distribution controls bioaccessibility, thereby directly impacting health risk. This study seeks to correlate Pb-containing particle size and mineral composition with lability and bioaccessibility in mine tailings subjected to weathering in a semi-arid environment. We employed X-ray absorption spectroscopy (XAS) and X-ray fluorescence (XRF), coupled with sequential chemical extractions, to study Pb speciation in tailings from the semi-arid Arizona Klondyke State Superfund Site. Representative samples ranging in pH from 2.6 to 5.4 were selected for in-depth study of Pb solid-phase speciation. The principle lead-bearing phase was plumbojarosite (PbFe6(SO4)4(OH)12), but anglesite (PbSO4) and iron oxide-sorbed Pb were also observed. Anglesite, the most bioavailable mineral species of lead identified in this study, was enriched in surficial tailings samples, where Pb concentrations in the clay size fraction were 2–3 times higher by mass relative to bulk. A mobile and bioaccessible Pb phase accumulates in surficial tailings, with a corresponding increase in risk of human exposure to atmospheric particles. PMID:22553941

Kinetics of heavy metal adsorption and desorption in soil: Developing a unified model based on chemical speciation

NASA Astrophysics Data System (ADS)

Peng, Lanfang; Liu, Paiyu; Feng, Xionghan; Wang, Zimeng; Cheng, Tao; Liang, Yuzhen; Lin, Zhang; Shi, Zhenqing

2018-03-01

Predicting the kinetics of heavy metal adsorption and desorption in soil requires consideration of multiple heterogeneous soil binding sites and variations of reaction chemistry conditions. Although chemical speciation models have been developed for predicting the equilibrium of metal adsorption on soil organic matter (SOM) and important mineral phases (e.g. Fe and Al (hydr)oxides), there is still a lack of modeling tools for predicting the kinetics of metal adsorption and desorption reactions in soil. In this study, we developed a unified model for the kinetics of heavy metal adsorption and desorption in soil based on the equilibrium models WHAM 7 and CD-MUSIC, which specifically consider metal kinetic reactions with multiple binding sites of SOM and soil minerals simultaneously. For each specific binding site, metal adsorption and desorption rate coefficients were constrained by the local equilibrium partition coefficients predicted by WHAM 7 or CD-MUSIC, and, for each metal, the desorption rate coefficients of various binding sites were constrained by their metal binding constants with those sites. The model had only one fitting parameter for each soil binding phase, and all other parameters were derived from WHAM 7 and CD-MUSIC. A stirred-flow method was used to study the kinetics of Cd, Cu, Ni, Pb, and Zn adsorption and desorption in multiple soils under various pH and metal concentrations, and the model successfully reproduced most of the kinetic data. We quantitatively elucidated the significance of different soil components and important soil binding sites during the adsorption and desorption kinetic processes. Our model has provided a theoretical framework to predict metal adsorption and desorption kinetics, which can be further used to predict the dynamic behavior of heavy metals in soil under various natural conditions by coupling other important soil processes.

Improve regional distribution and source apportionment of PM2.5 trace elements in China using inventory-observation constrained emission factors.

PubMed

Ying, Qi; Feng, Miao; Song, Danlin; Wu, Li; Hu, Jianlin; Zhang, Hongliang; Kleeman, Michael J; Li, Xinghua

2018-05-15

Contributions to 15 trace elements in airborne particulate matter with aerodynamic diameters <2.5μm (PM 2.5 ) in China from five major source sectors (industrial sources, residential sources, transportation, power generation and windblown dust) were determined using a source-oriented Community Multiscale Air Quality (CMAQ) model. Using emission factors in the composite speciation profiles from US EPA's SPECIATE database for the five sources leads to relatively poor model performance at an urban site in Beijing. Improved predictions of the trace elements are obtained by using adjusted emission factors derived from a robust multilinear regression of the CMAQ predicted primary source contributions and observation at the urban site. Good correlations between predictions and observations are obtained for most elements studied with R>0.5, except for crustal elements Al, Si and Ca, particularly in spring. Predicted annual and seasonal average concentrations of Mn, Fe, Zn and Pb in Nanjing and Chengdu are also consistently improved using the adjusted emission factors. Annual average concentration of Fe is as high as 2.0μgm -3 with large contributions from power generation and transportation. Annual average concentration of Pb reaches 300-500ngm -3 in vast areas, mainly from residential activities, transportation and power generation. The impact of high concentrations of Fe on secondary sulfate formation and Pb on human health should be evaluated carefully in future studies. Copyright © 2017 Elsevier B.V. All rights reserved.

Understanding the tissue effects of tribo-corrosion: uptake, distribution, and speciation of cobalt and chromium in human bone cells.

PubMed

Shah, Karan M; Quinn, Paul D; Gartland, Alison; Wilkinson, J Mark

2015-01-01

Cobalt and chromium species are released in the local tissues as a result of tribo-corrosion, and affect bone cell survival and function. However we have little understanding of the mechanisms of cellular entry, intracellular distribution, and speciation of the metals that result in impaired bone health. Here we used synchrotron based X-ray fluorescence (XRF), X-ray absorption spectroscopy (XAS), and fluorescent-probing approaches of candidate receptors P2X7R and divalent metal transporter-1 (DMT-1), to better understand the entry, intra-cellular distribution and speciation of cobalt (Co) and chromium (Cr) in human osteoblasts and primary human osteoclasts. We found that both Co and Cr were most highly localized at nuclear and perinuclear sites in osteoblasts, suggesting uptake through cell membrane transporters, and supported by a finding that P2X7 receptor blockade reduced cellular entry of Co. In contrast, metal species were present at discrete sites corresponding to the basolateral membrane in osteoclasts, suggesting cell entry by endocytosis and trafficking through a functional secretory domain. An intracellular reduction of Cr6+ to Cr3+ was the only redox change observed in cells treated with Co2+, Cr3+, and Cr6+. Our data suggest that the cellular uptake and processing of Co and Cr differs between osteoblasts and osteoclasts. © 2014 The Authors. Journal of Orthopaedic Research published by Wiley Periodicals, Inc. on behalf of the Orthopaedic Research Society.

The Molecular Basis of Memory

PubMed Central

2012-01-01

We propose a tripartite biochemical mechanism for memory. Three physiologic components are involved, namely, the neuron (individual and circuit), the surrounding neural extracellular matrix, and the various trace metals distributed within the matrix. The binding of a metal cation affects a corresponding nanostructure (shrinking, twisting, expansion) and dielectric sensibility of the chelating node (address) within the matrix lattice, sensed by the neuron. The neural extracellular matrix serves as an electro-elastic lattice, wherein neurons manipulate multiple trace metals (n > 10) to encode, store, and decode coginive information. The proposed mechanism explains brains low energy requirements and high rates of storage capacity described in multiples of Avogadro number (NA = 6 × 1023). Supportive evidence correlates memory loss to trace metal toxicity or deficiency, or breakdown in the delivery/transport of metals to the matrix, or its degradation. Inherited diseases revolving around dysfunctional trace metal metabolism and memory dysfunction, include Alzheimer's disease (Al, Zn, Fe), Wilson’s disease (Cu), thalassemia (Fe), and autism (metallothionein). The tripartite mechanism points to the electro-elastic interactions of neurons with trace metals distributed within the neural extracellular matrix, as the molecular underpinning of “synaptic plasticity” affecting short-term memory, long-term memory, and forgetting. PMID:23050060

Ionic liquid-based extraction followed by graphite-furnace atomic absorption spectrometry for the determination of trace heavy metals in high-purity iron metal.

PubMed

Matsumiya, Hiroaki; Kato, Tatsuya; Hiraide, Masataka

2014-02-01

The analysis of high-purity materials for trace impurities is an important and challenging task. The present paper describes a facile and sensitive method for the determination of trace heavy metals in high-purity iron metal. Trace heavy metals in an iron sample solution were rapidly and selectively preconcentrated by the extraction into a tiny volume of an ionic liquid [1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide] for the determination by graphite-furnace atomic absorption spectrometry (GFAAS). A nitrogen-donating neutral ligand, 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ), was found to be effective in the ionic liquid-based selective extraction, allowing the nearly complete (~99.8%) elimination of the iron matrix. The combination with the optimized GFAAS was successful. The detectability reached sub-μg g(-1) levels in iron metal. The novel use of TPTZ in ionic liquid-based extraction followed by GFAAS was successfully applied to the determination of traces of Co, Ni, Cu, Cd, and Pb in certified reference materials for high-purity iron metal. © 2013 Published by Elsevier B.V.

Vegetation and Cold Trapping Modulating Elevation-dependent Distribution of Trace Metals in Soils of a High Mountain in Eastern Tibetan Plateau.

PubMed

Bing, Haijian; Wu, Yanhong; Zhou, Jun; Li, Rui; Luo, Ji; Yu, Dong

2016-04-07

Trace metals adsorbed onto fine particles can be transported long distances and ultimately deposited in Polar Regions via the cold condensation effect. This study indicated the possible sources of silver (Ag), cadmium (Cd), copper (Cu), lead (Pb), antimony (Sb) and zinc (Zn) in soils on the eastern slope of Mt. Gongga, eastern Tibetan Plateau, and deciphered the effects of vegetation and mountain cold condensation on their distributions with elevation. The metal concentrations in the soils were comparable to other mountains worldwide except the remarkably high concentrations of Cd. Trace metals with high enrichment in the soils were influenced from anthropogenic contributions. Spatially, the concentrations of Cu and Zn in the surface horizons decreased from 2000 to 3700 m a.s.l., and then increased with elevation, whereas other metals were notably enriched in the mid-elevation area (approximately 3000 m a.s.l.). After normalization for soil organic carbon, high concentrations of Cd, Pb, Sb and Zn were observed above the timberline. Our results indicated the importance of vegetation in trace metal accumulation in an alpine ecosystem and highlighted the mountain cold trapping effect on trace metal deposition sourced from long-range atmospheric transport.

A XANES Study of Sulfur Speciation and Reactivity in Cokes for Anodes Used in Aluminum Production

NASA Astrophysics Data System (ADS)

Jahrsengene, Gøril; Wells, Hannah C.; Rørvik, Stein; Ratvik, Arne Petter; Haverkamp, Richard G.; Svensson, Ann Mari

2018-03-01

Availability of anode raw materials in the growing aluminum industry results in a wider range of petroleum cokes being used to produce carbon anodes. The boundary between anode grade cokes and what previously was considered non-anode grades are no longer as distinct as before, leading to introduction of cokes with higher sulfur and higher trace metal impurity content in anode manufacturing. In this work, the chemical nature of sulfur in five industrial cokes, ranging from 1.42 to 5.54 wt pct S, was investigated with K-edge XANES, while the reactivity of the cokes towards CO2 was measured by a standard mass loss test. XANES identified most of the sulfur as organic sulfur compounds. In addition, a significant amount is identified (16 to 53 pct) as S-S bound sulfur. A strong inverse correlation is observed between CO2-reactivity and S-S bound sulfur in the cokes, indicating that the reduction in reactivity is more dependent on the amount of this type of sulfur compound rather than the total amount of sulfur or the amount of organic sulfur.

A XANES Study of Sulfur Speciation and Reactivity in Cokes for Anodes Used in Aluminum Production

NASA Astrophysics Data System (ADS)

Jahrsengene, Gøril; Wells, Hannah C.; Rørvik, Stein; Ratvik, Arne Petter; Haverkamp, Richard G.; Svensson, Ann Mari

2018-06-01

Availability of anode raw materials in the growing aluminum industry results in a wider range of petroleum cokes being used to produce carbon anodes. The boundary between anode grade cokes and what previously was considered non-anode grades are no longer as distinct as before, leading to introduction of cokes with higher sulfur and higher trace metal impurity content in anode manufacturing. In this work, the chemical nature of sulfur in five industrial cokes, ranging from 1.42 to 5.54 wt pct S, was investigated with K-edge XANES, while the reactivity of the cokes towards CO2 was measured by a standard mass loss test. XANES identified most of the sulfur as organic sulfur compounds. In addition, a significant amount is identified (16 to 53 pct) as S-S bound sulfur. A strong inverse correlation is observed between CO2-reactivity and S-S bound sulfur in the cokes, indicating that the reduction in reactivity is more dependent on the amount of this type of sulfur compound rather than the total amount of sulfur or the amount of organic sulfur.

Microfluidic high performance liquid chromatography-chip hyphenation to inductively coupled plasma-mass spectrometry.

PubMed

Bishop, David P; Blanes, Lucas; Wilson, Alexander B; Wilbanks, Thor; Killeen, Kevin; Grimm, Rudolf; Wenzel, Ross; Major, Derek; Macka, Mirek; Clarke, David; Schmid, Robin; Cole, Nerida; Doble, Philip A

2017-05-12

The Agilent Chip Cube Interface is a microfluidic chip-based technology originally designed for nanospray molecular mass spectrometry in which the sample enrichment, nano-column, tubing, connectors and spray tip were integrated into a single biocompatible chip. Here we describe the hyphenation of the Chip Cube Interface to ICP-MS via modification of the standard HPLC chip design and a new total consumption nebuliser suitable for flow rates as low as 300nLmin -1 . The potential of the instrument to eliminate common nanoLC - ICP-MS shortcomings such as leaks, blockages and band-broadening was demonstrated via analysis of cyanocobalamin in equine plasma. The method was linear over three orders of magnitude with an r 2 of 0.9999, the peak area repeatability was 1.9% (n=7), and the detection limit was 14ngmL -1 . This novel configuration of the Chip Cube Interface coupled to ICP-MS is a suitable platform for the analysis of biomolecules associated with trace metals and speciation applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Trace elements in agroecosystems and impacts on the environment.

PubMed

He, Zhenli L; Yang, Xiaoe E; Stoffella, Peter J

2005-01-01

Trace elements mean elements present at low concentrations (mg kg-1 or less) in agroecosystems. Some trace elements, including copper (Cu), zinc (Zn), manganese (Mn), iron (Fe), molybdenum (Mo), and boron (B) are essential to plant growth and are called micronutrients. Except for B, these elements are also heavy metals, and are toxic to plants at high concentrations. Some trace elements, such as cobalt (Co) and selenium (Se), are not essential to plant growth but are required by animals and human beings. Other trace elements such as cadmium (Cd), lead (Pb), chromium (Cr), nickel (Ni), mercury (Hg), and arsenic (As) have toxic effects on living organisms and are often considered as contaminants. Trace elements in an agroecosystem are either inherited from soil parent materials or inputs through human activities. Soil contamination with heavy metals and toxic elements due to parent materials or point sources often occurs in a limited area and is easy to identify. Repeated use of metal-enriched chemicals, fertilizers, and organic amendments such as sewage sludge as well as wastewater may cause contamination at a large scale. A good example is the increased concentration of Cu and Zn in soils under long-term production of citrus and other fruit crops. Many chemical processes are involved in the transformation of trace elements in soils, but precipitation-dissolution, adsorption-desorption, and complexation are the most important processes controlling bioavailability and mobility of trace elements in soils. Both deficiency and toxicity of trace elements occur in agroecosystems. Application of trace elements in fertilizers is effective in correcting micronutrient deficiencies for crop production, whereas remediation of soils contaminated with metals is still costly and difficult although phytoremediation appears promising as a cost-effective approach. Soil microorganisms are the first living organisms subjected to the impacts of metal contamination. Being responsive and sensitive, changes in microbial biomass, activity, and community structure as a result of increased metal concentration in soil may be used as indicators of soil contamination or soil environmental quality. Future research needs to focus on the balance of trace elements in an agroecosystem, elaboration of soil chemical and biochemical parameters that can be used to diagnose soil contamination with or deficiency in trace elements, and quantification of trace metal transport from an agroecosystem to the environment.

Trace metals in the brain: allosteric modulators of ligand-gated receptor channels, the case of ATP-gated P2X receptors.

PubMed

Huidobro-Toro, J Pablo; Lorca, Ramón A; Coddou, Claudio

2008-03-01

Zinc and copper are indispensable trace metals for life with a recognized role as catalysts in enzyme actions. We now review evidence supporting the role of trace metals as novel allosteric modulators of ionotropic receptors: a new and fundamental physiological role for zinc and copper in neuronal and brain excitability. The review is focussed on ionotropic receptor channels including nucleotide receptors, in particular the P2X receptor family. Since zinc and copper are stored within synaptic vesicles in selected brain regions, and released to the synaptic cleft upon electrical nerve ending depolarization, it is plausible that zinc and copper reach concentrations in the synapse that profoundly affect ligand-gated ionic channels, including the ATP-gated currents of P2X receptors. The identification of key P2X receptor amino acids that act as ligands for trace metal coordination, carves the structural determinants underlying the allosteric nature of the trace metal modulation. The recognition that the identified key residues such as histidines, aspartic and glutamic acids or cysteines in the extracellular domain are different for each P2X receptor subtype and may be different for each metal, highlights the notion that each P2X receptor subtype evolved independent strategies for metal coordination, which form upon the proper three-dimensional folding of the receptor channels. The understanding of the molecular mechanism of allosteric modulation of ligand-operated ionic channels by trace metals is a new contribution to metallo-neurobiology.

Caddisflies Hydropsyche spp. as biomonitors of trace metal bioavailability thresholds causing disturbance in freshwater stream benthic communities.

PubMed

Awrahman, Zmnako A; Rainbow, Philip S; Smith, Brian D; Khan, Farhan R; Fialkowski, Wojciech

2016-09-01

Demonstration of an ecotoxicological effect of raised toxic metal bioavailabilities on benthic macroinvertebrate communities in contaminated freshwater streams typically requires the labour-intensive identification and quantification of such communities before the application of multivariate statistical analysis. A simpler approach is the use of accumulated trace metal concentrations in a metal-resistant biomonitor to define thresholds that indicate the presence of raised trace metal bioavailabilities causing ecotoxicological responses in populations of more metal-sensitive members of the community. We explore further the hypothesis that concentrations of toxic metals in larvae of species of the caddisfly genus Hydropsyche can be used to predict metal-driven ecotoxicological responses in more metal-sensitive mayflies, especially ephemerellid and heptageniid mayflies, in metal-contaminated rivers. Comparative investigation of two caddisflies, Hydropsyche siltalai and Hydropsyche angustipennis, from metal-contaminated rivers in Cornwall and Upper Silesia, Poland respectively, has provided preliminary evidence that this hypothesis is applicable across caddisfly species and contaminated river systems. Use of a combined toxic unit approach, relying on independent data sets, suggested that copper and probably also arsenic are the drivers of mayfly ecotoxicity in the River Hayle and the Red River in Cornwall, while cadmium, lead and zinc are the toxic agents in the Biala Przemsza River in Poland. This approach has great potential as a simple tool to detect the more subtle effects of mixed trace metal contamination in freshwater systems. An informed choice of suitable biomonitor extends the principle to different freshwater habitats over different ranges of severity of trace metal contamination. Copyright © 2016 Elsevier Ltd. All rights reserved.

Trace metal distribution and control in the pilot-scale bubbling fluidized bed combustor equipped with the pulse-jet fabric filter, limestone injection, and the humidification reactor.

PubMed

Kouvo, Petri

2003-04-01

This work focused on trace metal behavior and removal in a fabric filter or in a humidification reactor during the cofiring of sawdust and refuse-derived fuels (RDFs) in a pilot-scale bubbling fluidized bed (BFB) boiler. Trace metal emissions measurements before and after the fabric filter revealed that removal efficiency in the fabric filter was in the range of 80-100%, and that the European Union (EU) Directive on Incineration of Waste restrictions for trace metal emissions are easily achieved even if addition of RDFs substantially increases the concentration of trace metals in fuel blends. Limestone injection enhanced the removal of As and Se but had no noticeable effect on the removal of other trace metals. Extensive formation of HgCl2 and condensation on fly ash particles during sawdust plus 40% RDF cofiring resulted in a 92% Hg removal efficiency in the fabric filter. Limestone injection had no effect on the Hg removal in the fabric filter but decreased the Hg removal in a humidification reactor from 40 to 28%. Results of the bed material and fly ash analysis suggested capture of Cu, Pb, Mn, Ni, and Zn in the bed material but also suggested that these metals may be released from the bed if the fuel characteristics or process conditions are changed.

Speciation and distribution characteristics of heavy metals and pollution assessments in the sediments of Nashina Lake, Heilongjiang, China.

PubMed

Li, Miao; Zang, Shuying; Xiao, Haifeng; Wu, Changshan

2014-05-01

Sediment core samples from Nashina Lake, Heilongjiang, China were collected using a gravity sampler. The cores were sliced horizontally at 1 cm each to determine the particle size, total concentrations and speciation of Cd, Cr, Cu, Mn, Ni, Pb, and Zn. Total concentrations of heavy metals were extracted using an acid mixture (containing hydro fluoric acid, nitric acid, and sulphuric acid) and analyzed using an inductively coupled plasma spectrometry. A sequential extraction procedure was employed to separate chemical species. Analysis of results indicate that the concentrations of heavy metals in the sediments of Nashina Lake in descending order are Mn, Cr, Zn, Pb, Ni, Cu, and Cd. The ratios of the average concentrations of four heavy metals (e.g.Cr, Cu, Ni, Zn) to their background values were >1; and those of Mn, Cd, and Pb were >1. Moreover, some toxic metals were mainly distributed in bioavailable fractions. For instance, both Cd and Mn were typically found in Acid-extractable species or Fe-Mn oxide species, and thus can be easily remobilized and enter the food chain. Finally, the analysis of geo-accumulation index showed that anthropogenic pollution levels of Cr, Cu, Mn, Ni, Zn were low, but those of Pb and Cd were at the moderate level. As both Pb and Cd are toxic metals, it is highly necessary to prohibit their transformation and accumulation in the sediments.

ENVIRONMENTAL MANAGEMENT SCIENCE PROGRAM PROJECT NUMBER 87016 CO-PRECIPITATION OF TRACE METALS IN GROUNDWATER AND VADOSE ZONE CALCITE: IN SITU CONTAINMENT AND STABILIZATION OF STRONTIUM-90 AND OTHER DIVALENT METALS AND RADIONUCLIDES AT ARID WESTERN DOE SITES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferris, F. Grant; Fujita, Yoshiko; Smith, Robert W.

2004-06-15

Radionuclide and metal contaminants are present in the vadose zone and groundwater throughout the U.S. Department of Energy (DOE) weapons complex. In situ containment and stabilization of these contaminants in vadose zones or groundwater is a cost-effective treatment strategy. Our facilitated approach relies upon the hydrolysis of introduced urea to cause the acceleration of calcium carbonate precipitation (and trace metal coprecipitation) by increasing groundwater pH and alkalinity (Fujita et al., 2000; Warren et al., 2001). Subsurface urea hydrolysis is catalyzed by the urease enzyme, which may be either introduced with the urea or produced in situ by ubiquitous subsurface ureamore » hydrolyzing microorganisms. Because the precipitation processes are irreversible and many western aquifers are saturated with respect to calcite, the co-precipitated metals and radionuclides will be effectively removed from groundwater. The rate at which trace metals are incorporated into calcite is a function of calcite precipitation kinetics, adsorption interactions between the calcite surface and the trace metal in solution (Zachara et al., 1991), solid solution properties of the trace metal in calcite (Tesoriero and Pankow, 1996), and also the surfaces upon which the calcite is precipitating. A fundamental understanding of the coupling of calcite precipitation and trace metal partitioning, and how this occurs in aquifers and vadose environments is lacking. This report summarizes work undertaken during the second year of this project.« less

Chemical speciation and potential mobility of heavy metals in the soil of former tin mining catchment.

PubMed

Ashraf, M A; Maah, M J; Yusoff, I

2012-01-01

This study describes the chemical speciation of Pb, Zn, Cu, Cr, As, and Sn in soil of former tin mining catchment. Total five sites were selected for sampling and subsequent subsamples were collected from each site in order to create a composite sample for analysis. Samples were analysed by the sequential extraction procedure using optical emission spectrometry (ICP OES). Small amounts of Cu, Cr, and As retrieved from the exchangeable phase, the ready available for biogeochemical cycles in the ecosystem. Low quantities of Cu and As could be taken up by plants in these kind of acidic soils. Zn not detected in the bioavailable forms while Pb is only present in negligible amounts in very few samples. The absence of mobile forms of Pb eliminates the toxic risk both in the trophic chain and its migration downwards the soil profile. The results also indicate that most of the metals have high abundance in residual fraction indicating lithogenic origin and low bioavailability of the metals in the studied soil. The average potential mobility for the metals giving the following order: Sn > Cu > Zn > Pb > Cr > As.

Chemical Speciation and Potential Mobility of Heavy Metals in the Soil of Former Tin Mining Catchment

PubMed Central

Ashraf, M. A.; Maah, M. J.; Yusoff, I.

2012-01-01

This study describes the chemical speciation of Pb, Zn, Cu, Cr, As, and Sn in soil of former tin mining catchment. Total five sites were selected for sampling and subsequent subsamples were collected from each site in order to create a composite sample for analysis. Samples were analysed by the sequential extraction procedure using optical emission spectrometry (ICP OES). Small amounts of Cu, Cr, and As retrieved from the exchangeable phase, the ready available for biogeochemical cycles in the ecosystem. Low quantities of Cu and As could be taken up by plants in these kind of acidic soils. Zn not detected in the bioavailable forms while Pb is only present in negligible amounts in very few samples. The absence of mobile forms of Pb eliminates the toxic risk both in the trophic chain and its migration downwards the soil profile. The results also indicate that most of the metals have high abundance in residual fraction indicating lithogenic origin and low bioavailability of the metals in the studied soil. The average potential mobility for the metals giving the following order: Sn > Cu > Zn > Pb > Cr > As. PMID:22566758

Trace Elements in Ovaries: Measurement and Physiology.

PubMed

Ceko, Melanie J; O'Leary, Sean; Harris, Hugh H; Hummitzsch, Katja; Rodgers, Raymond J

2016-04-01

Traditionally, research in the field of trace element biology and human and animal health has largely depended on epidemiological methods to demonstrate involvement in biological processes. These studies were typically followed by trace element supplementation trials or attempts at identification of the biochemical pathways involved. With the discovery of biological molecules that contain the trace elements, such as matrix metalloproteinases containing zinc (Zn), cytochrome P450 enzymes containing iron (Fe), and selenoproteins containing selenium (Se), much of the current research focuses on these molecules, and, hence, only indirectly on trace elements themselves. This review focuses largely on two synchrotron-based x-ray techniques: X-ray absorption spectroscopy and x-ray fluorescence imaging that can be used to identify the in situ speciation and distribution of trace elements in tissues, using our recent studies of bovine ovaries, where the distribution of Fe, Se, Zn, and bromine were determined. It also discusses the value of other techniques, such as inductively coupled plasma mass spectrometry, used to garner information about the concentrations and elemental state of the trace elements. These applications to measure trace elemental distributions in bovine ovaries at high resolutions provide new insights into possible roles for trace elements in the ovary. © 2016 by the Society for the Study of Reproduction, Inc.

Field-scale study of the influence of differing remediation strategies on trace metal geochemistry in metal mine tailings from the Irish Midlands.

PubMed

Perkins, William T; Bird, Graham; Jacobs, Suzanne R; Devoy, Cora

2016-03-01

Mine tailings represent a globally significant source of potentially harmful elements (PHEs) to the environment. The management of large volumes of mine tailings represents a major challenge to the mining industry and environmental managers. This field-scale study evaluates the impact of two highly contrasting remediation approaches to the management and stabilisation of mine tailings. The geochemistry of the tailings, overlying amendment layers and vegetation are examined in the light of the different management approaches. Pseudo-total As, Cd and Pb concentrations and solid-state partitioning (speciation), determined via sequential extraction, were established for two Tailings Management Facilities (TMFs) in Ireland subjected to the following: (1) a 'walk-away' approach (Silvermines) and (2) application of an amendment layer (Galmoy). PHE concentrations in roots and herbage of grasses growing on the TMFs were also determined. Results identify very different PHE concentration profiles with depth through the TMFs and the impact of remediation approach on concentrations and their potential bioavailability in the rooting zone of grass species. Data also highlight the importance of choice of grass species in remediation approaches and the benefits of relatively shallow-rooting Agrostis capillaris and Festuca rubra varieties. In addition, data from the Galmoy TMF indicate the importance of regional soil geochemistry for interpreting the influence of the PHE geochemistry of capping and amendment layers applied to mine tailings.

Levels and distribution of heavy metals in atmospheric particular matters over the northern South China Sea.

PubMed

Xu, Weihai; Yan, Wen; Zhang, Gan; Li, Jun; Miao, Li; Huang, Weixia

2014-01-01

Oceans play a significant role in the cycling of trace metals and persistent organic pollutants. In this study, aerosol samples covering the whole northern South China Sea (SCS) were collected in 2005 and 2007, respectively, for analysis of trace metals and major elements. The levels of trace metals detected ranged from 0.514 to 119 ng/m(3) in 2005 and from 0.130 to 24.2 ng/m(3) in 2007, respectively. Cu, Zn, and Pb were the three predominant metals with high enrichment factors (>10), indicating the strong anthropogenic inputs. The trace metals over SCS were comparable to the values in suburban and background sites of South China, but generally higher than those over other seas and oceans. Considering the fact that they were influenced by their proximity to source regions and air mass origins, the elevated metals in 2005 were probably attributed to the strong wind and long-range atmospheric transport driven by Asian monsoon.

Reconstructing Early Industrial Contributions to Legacy Trace Metal Contamination in Southwestern Pennsylvania

NASA Astrophysics Data System (ADS)

Rossi, R.; Bain, D.; Hillman, A. L.; Pompeani, D. P.; Abbott, M. B.

2015-12-01

The remobilization of legacy contamination stored in floodplain sediments remains a threat to ecosystem and human health, particularly with potential changes in global precipitation patterns and flooding regimes. Vehicular and industrial emissions are often the dominant, recognized source of anthropogenic trace metal loadings to ecosystems today. However, loadings from early industrial activities are poorly characterized and potential sources of trace metal inputs. While potential trace metal contamination from these activities is recognized (e.g., the historical use of lead arsenate as a pesticide), the magnitude and distribution of legacy contamination is often unknown. This presentation reconstructs a lake sediment record of trace metal inputs from an oxbow lake in Southwestern Pennsylvania. Sediment cores were analyzed for major and trace metal chemistry, carbon to nitrogen ratios, bulk density, and magnetic susceptibility. Sediment trace metal chemistry in this approximately 250 year record (180 cm) record changes in land use and industry both in the 19th century and the 20th century. Of particular interest is early 19th century loadings of arsenic and calcium to the lake, likely attributable to pesticides and lime used in tanning processes near the lake. After this period of tanning dominated inputs, sediment barium concentrations rise, likely reflecting the onset of coal mining operations and resulting discharge of acid mine drainage to surface waters. In the 20th century portion of our record (70 -20 cm), patterns in sediment zinc, cadmium, and lead concentrations are dominated by the opening and closing of the nearby Donora Zinc Works and the American Steel & Wire Works, infamous facilities in the history of air quality regulation. The most recent sediment chemistry records periods include the enactment of air pollution legislation (~ 35 cm), and the phase out of tetraethyl leaded gasoline (~30 cm). Our study documents the impact of early industry in the Southwestern Pennsylvania region, as well as early industrial coal production/consumption on legacy trace metal contamination. This record suggests that some early industrial processes can rival more recent metal fluxes and should be carefully considered in modern assessments of legacy sediment metal contamination.

Trace metals accumulation in Bacopa monnieri and their bioaccessibility.

PubMed

Srikanth Lavu, Rama Venkata; Prasad, Majeti Narasimha Vara; Pratti, Varalakshmi Lalithya; Meißner, Ralph; Rinklebe, Jörg; Van De Wiele, Tom; Tack, Filip; Du Laing, Gijs

2013-08-01

Bacopa monnieri is commonly known as "Brahmi" or "Water hyssop" and is a source of nootropic drugs. Aboveground parts of plant samples collected from peri-urban Indian areas were analysed for total trace metal concentrations. Subsequently, three samples with high concentrations of Cd and Pb were subjected to in vitro gastrointestinal digestion to assess the bioaccessibility of the trace metals in these plants. The total concentrations of trace metals on a dry weight basis were 1.3 to 6.7 mg·kg⁻¹ Cd, 1.5 to 22 mg·kg⁻¹ Pb, 36 to 237 mg·kg⁻¹ Cu, and 78 to 186 mg·kg⁻¹ Zn. The majority of Bacopa monnieri samples exceeded threshold limits of Cd, Pb, Cu, and Zn for use as raw medicinal plant material or direct consumption. Therefore, it is necessary to evaluate Bacopa monnieri collected in nature for their trace metal content prior to human consumption and preparation of herbal formulations. Georg Thieme Verlag KG Stuttgart · New York.

How healthy is urban horticulture in high traffic areas? Trace metal concentrations in vegetable crops from plantings within inner city neighbourhoods in Berlin, Germany.

PubMed

Säumel, Ina; Kotsyuk, Iryna; Hölscher, Marie; Lenkereit, Claudia; Weber, Frauke; Kowarik, Ingo

2012-06-01

Food production by urban dwellers is of growing importance in developing and developed countries. Urban horticulture is associated with health risks as crops in urban settings are generally exposed to higher levels of pollutants than those in rural areas. We determined the concentration of trace metals in the biomass of different horticultural crops grown in the inner city of Berlin, Germany, and analysed how the local setting shaped the concentration patterns. We revealed significant differences in trace metal concentrations depending on local traffic, crop species, planting style and building structures, but not on vegetable type. Higher overall traffic burden increased trace metal content in the biomass. The presence of buildings and large masses of vegetation as barriers between crops and roads reduced trace metal content in the biomass. Based on this we discuss consequences for urban horticulture, risk assessment, and planting and monitoring guidelines for cultivation and consumption of crops. Copyright © 2012 Elsevier Ltd. All rights reserved.

Trace metals in sediments and benthic animals from aquaculture ponds near a mangrove wetland in Southern China.

PubMed

Wu, Hao; Liu, Jinling; Bi, Xiangyang; Lin, Guanghui; Feng, Christopher C; Li, Zhengjie; Qi, Fei; Zheng, Tianling; Xie, Liqi

2017-04-15

In this study, we measured the concentrations of trace metals (Cr, Cu, Zn, As, Cd, Pb and Hg) in typical cultured animals (crabs, clams, and shrimps) and sediments from aquaculture ponds nearby mangrove wetlands in Zhangjiang estuary, China. The contents of Cr, Cu, Cd, and Pb in mangrove sediments were significantly higher than those in pond sediments, while an inverse distribution was observed for Zn, As, and Hg. Significantly higher concentrations of trace metals were found in clams from the mangrove mudflats compared to those from the aquaculture ponds. The sources of trace metals in the clams were primarily from organic fertilizer, whereas those in the shrimp were from contaminated sediment. The results of geo-accumulation index and the ecological risk assessment indicated that the aquaculture ponds near the mangrove wetlands in this subtropical estuary posed a special risk of endogenous and exogenous trace metal pollution to nearby systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Assessment of trace metal pollution in sediments and intertidal fauna at the coast of Cameroon.

PubMed

Ngeve, Magdalene N; Leermakers, Martine; Elskens, Marc; Kochzius, Marc

2015-06-01

Coastal systems act as a boundary between land and sea. Therefore, assessing pollutant concentrations at the coast will provide information on the impact that land-based anthropogenic activities have on marine ecosystems. Sediment and fauna samples from 13 stations along the whole coast of Cameroon were analyzed to assess the level of trace metal pollution in sediments and intertidal fauna. Sediments showed enrichment of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn. However, pollution of greater concern was observed for Cd, Cr, Cu, Ni, and Zn at the northern stations. Some sites recorded trace metal levels higher than recommended in sediment quality guidelines. Species diversity was low, and high bioaccumulation of trace metals was observed in biological samples. Some edible gastropod species accumulated trace metals above the safety limits of the World Health Organization, European Medicine Agency, and the US Environment Protection Agency. Although industrial pollution is significant along Cameroon's coast, natural pollution from the volcano Mount Cameroon is also of concern.

PRESERVATION OF TRACE METALS IN WATER SAMPLES

EPA Science Inventory

Questions about trace metal preservation are resurfacing because the health effect risks associated with certain metals continue to drive the required reporting limits lower. Inductively coupled plasma-mass spectrometry was used in this study to analyze preservation of samples co...

Short-term acute hypercapnia affects cellular responses to trace metals in the hard clams Mercenaria mercenaria.

PubMed

Ivanina, Anna V; Beniash, Elia; Etzkorn, Markus; Meyers, Tiffany B; Ringwood, Amy H; Sokolova, Inna M

2013-09-15

Estuarine and coastal habitats experience large fluctuations of environmental factors such as temperature, salinity, partial pressure of CO2 ( [Formula: see text] ) and pH; they also serve as the natural sinks for trace metals. Benthic filter-feeding organisms such as bivalves are exposed to the elevated concentrations of metals in estuarine water and sediments that can strongly affect their physiology. The effects of metals on estuarine organisms may be exacerbated by other environmental factors. Thus, a decrease in pH caused by high [Formula: see text] (hypercapnia) can modulate the effects of trace metals by affecting metal bioavailability, accumulation or binding. To better understand the cellular mechanisms of interactions between [Formula: see text] and trace metals in marine bivalves, we exposed isolated mantle cells of the hard clams (Mercenaria mercenaria) to different levels of [Formula: see text] (0.05, 1.52 and 3.01 kPa) and two major trace metal pollutants - cadmium (Cd) and copper (Cu). Elevated [Formula: see text] resulted in a decrease in intracellular pH (pHi) of the isolated mantle cells from 7.8 to 7.4. Elevated [Formula: see text] significantly but differently affected the trace metal accumulation by the cells. Cd uptake was suppressed at elevated [Formula: see text] levels while Cu accumulation has greatly accelerated under hypercapnic conditions. Interestingly, at higher extracellular Cd levels, labile intracellular Cd(2+) concentration remained the same, while intracellular levels of free Zn(2+) increased suggesting that Cd(2+) substitutes bound Zn(2+) in these cells. In contrast, Cu exposure did not affect intracellular Zn(2+) but led to a profound increase in the intracellular levels of labile Cu(2+) and Fe(2+). An increase in the extracellular concentrations of Cd and Cu led to the elevated production of reactive oxygen species under the normocapnic conditions (0.05 kPa [Formula: see text] ); surprisingly, this effect was mitigated in hypercapnia (1.52 and 3.01 kPa). Overall, our data reveal complex and metal-specific interactions between the cellular effects of trace metals and [Formula: see text] in clams and indicate that variations in environmental [Formula: see text] may modulate the biological effects of trace metals in marine organisms. Copyright © 2013 Elsevier B.V. All rights reserved.

Flotation as a remediation technique for heavily polluted dredged material. 2. Characterisation of flotated fractions.

PubMed

Cauwenberg, P; Verdonckt, F; Maes, A

1998-01-19

The particle size distribution and the metal speciation of the heavy metals were investigated on dredged sediment and on the fractions obtained by mechanical agitated (Denver) flotation. The transition metal ions (cadmium, copper, lead and zinc) were flotated specifically independent of the particle size. Particle size analysis, EDTA extraction and sequential extracts indicated that during flotation a redistribution of metals occurred due to the oxidation of metal sulphides. This oxidation process was more pronounced when the flotation was performed at higher pH values and resulted in a decrease in flotation specificity.

Trace metal accumulation in soil and their phytoavailability as affected by greenhouse types in north China.

PubMed

Yang, Lanqin; Huang, Biao; Mao, Mingcui; Yao, Lipeng; Hickethier, Martina; Hu, Wenyou

2015-05-01

Long-term heavy organic fertilizer application has linked greenhouse vegetable production (GVP) with trace metal contamination in north China. Given that trace metals release from fertilizers and their availability may be affected by discrepant environmental conditions, especially temperature under different greenhouses, this study investigated Cd, Cu, Pb, and Zn accumulation and contamination extent in soil as well as their phytoavailability under two major greenhouses in Tongshan, north China, namely solar greenhouse (SG) and round-arched plastic greenhouse (RAPG), to evaluate their presumed difference. The results showed significant Cd, Cu, Pb, and Zn accumulation in GVP soil by comparing with those in open-field soil, but their accumulation extent and rates were generally greater in SG than those in RAPG. This may be related to more release of trace metals to soil due to the acceleration of decomposition and humification process of organic fertilizers under higher soil temperature in SG relative to that in RAPG. Overall, soil in both greenhouses was generally less polluted or moderately polluted by the study metals. Similarly, decreased soil pH and elevated soil available metals in SG caused higher trace metals in leaf vegetables in SG than those in RAPG, although there was no obvious risk via vegetable consumption under both greenhouses. Lower soil pH may be predominantly ascribed to more intensive farming practices in SG while elevated soil available metals may be attributed to more release of dissolved organic matter-metal complexes from soil under higher temperature in SG. The data provided in this study may assist in developing reasonable and sustainable fertilization strategies to abate trace metal contamination in both greenhouses.

Tolerance to cadmium in plants: the special case of hyperaccumulators.

PubMed

Verbruggen, Nathalie; Juraniec, Michal; Baliardini, Cecilia; Meyer, Claire-Lise

2013-08-01

On sols highly polluted by trace metallic elements the majority of plant species are excluders, limiting the entry and the root to shoot translocation of trace metals. However a rare class of plants called hyperaccumulators possess remarkable adaptation because those plants combine extremely high tolerance degrees and foliar accumulation of trace elements. Hyperaccumulators have recently gained considerable interest, because of their potential use in phytoremediation, phytomining and biofortification. On a more fundamental point of view hyperaccumulators of trace metals are case studies to understand metal homeostasis and detoxification mechanisms. Hyperaccumulation of trace metals usually depends on the enhancement of at least four processes, which are the absorption from the soil, the loading in the xylem in the roots and the unloading from the xylem in the leaves and the detoxification in the shoot. Cadmium is one of the most toxic trace metallic elements for living organisms and its accumulation in the environment is recognized as a worldwide concern. To date, only nine species have been recognized as Cd hyperaccumulators that is to say able to tolerate and accumulate more than 0.01 % Cd in shoot dry biomass. Among these species, four belong to the Brassicaceae family with Arabidopsis halleri and Noccaea caerulescens being considered as models. An update of our knowledge on the evolution of hyperaccumulators will be presented here.

Extension of coupled multispecies metal transport and speciation (TRANSPEC) model to soil.

PubMed

Bhavsar, Satyendra P; Gandhi, Nilima; Diamond, Miriam L

2008-01-01

Atmospheric deposition of metals emitted from mining operations has raised metal concentrations in the surrounding soils. This repository may be remobilized and act as a source of metals to nearby surface aquatic systems. It is important to understand metal dynamics and the impact of various chemistry and fate parameters on metal movement in the soil environment in order to evaluate risk associated with metals in terrestrial ecosystems and accurately establish critical discharge limits that are protective of aquatic biota. Here we extend our previously developed coupled multispecies metal fate-TRANsport and SPECiation/complexation (TRANSPEC) model, which was applicable to surface aquatic systems. The extended TRANSPEC, termed TRANSPEC-II, estimates the partition coefficient, K(d), between the soil-solid and -soluble phases using site-specific data and a semi-empirical regression model obtained from literature. A geochemical model calculates metal and species fractions in the dissolved and colloidal phases of the soil solution. The multispecies fugacity/aquivalence based fate-transport model then estimates inter-media transport rates such as leaching from soil, soil runoff, and water-sediment exchanges of each metal species. The model is illustratively applied to Ni in the Kelly Lake watershed (Sudbury, Ontario, Canada), where several mining operations are located. The model results suggest that the current atmospheric fallout supplies only 4% of Ni removed from soil through soil runoff and leaching. Soil runoff contributes about 20% of Ni entering into Kelly Lake with the rest coming from other sources. Leaching to groundwater, apart from runoff, is also a major loss process for Ni in the soil. A sensitivity analysis indicates that raising soil pH to above 6 may substantially reduce metal runoff and improve water quality of nearby water bodies that are impacted by runoff.

Trace-metal sources and their release from mine wastes: examples from humidity cell tests of hardrock mine waste and from Warrior Basin coal

USGS Publications Warehouse

Diehl, S.F.; Smith, Kathleen S.; Desborough, G.A.; White, W.W.; Lapakko, K.A.; Goldhaber, Martin B.; Fey, David L.

2003-01-01

To assess the potential impact of metal and acid contamination from mine-waste piles, it is important to identify the mineralogic source of trace metals and their mode of occurrence. Microscopic analysis of mine-waste samples from both hard-rock and coalmine waste samples demonstrate a microstructural control, as well as mineralogic control, on the source and release of trace metals into local water systems. The samples discussed herein show multiple periods of sulfide mineralization with varying concentrations of trace metals. In the first case study, two proprietary hard-rock mine-waste samples exposed to a series of humidity cell tests (which simulate intense chemical weathering conditions) generated acid and released trace metals. Some trace elements of interest were: arsenic (45-120 ppm), copper (60-320 ppm), and zinc (30-2,500 ppm). Untested and humidity cell-exposed samples were studied by X-ray diffraction, scanning electron microscope with energy dispersive X-ray (SEM/EDX), and electron microprobe analysis. Studies of one sample set revealed arsenic-bearing pyrite in early iron- and magnesium-rich carbonate-filled microveins, and iron-, copper-, arsenic-, antimony-bearing sulfides in later crosscutting silica-filled microveins. Post humidity cell tests indicated that the carbonate minerals were removed by leaching in the humidity cells, exposing pyrite to oxidative conditions. However, sulfides in the silica-filled veins were more protected. Therefore, the trace metals contained in the sulfides within the silica-filled microveins may be released to the surface and (or) ground water system more slowly over a greater time period. In the second case study, trace metal-rich pyrite-bearing coals from the Warrior Basin, Alabama were analyzed. Arsenic-bearing pyrite was observed in a late-stage pyrite phase in microfaults and microveins that crosscut earlier arsenic.

Accumulation, sources and health risks of trace metals in elevated geochemical background soils used for greenhouse vegetable production in southwestern China.

PubMed

Zhang, Haidong; Huang, Biao; Dong, Linlin; Hu, Wenyou; Akhtar, Mohammad Saleem; Qu, Mingkai

2017-03-01

Greenhouse vegetable cultivation with substantive manure and fertilizer input on soils with an elevated geochemical background can accumulate trace metals in soils and plants leading to human health risks. Studies on trace metal accumulation over a land use shift duration in an elevated geochemical background scenario are lacking. Accumulation characteristics of seven trace metals in greenhouse soil and edible plants were evaluated along with an assessment of the health risk to the consumers. A total of 118 greenhouse surface soils (0-20cm) and 30 vegetables were collected from Kunming City, Yunnan Province, southwestern China, and analyzed for total Cd, Pb, Cu, Zn, As, Hg, and Cr content by ICP-MS and AFS. The trace metals were ordered Cu>Cd>Hg>Zn>Pb>As>Cr in greenhouse soils accumulation level, and the geo-accumulation index suggested the soil more severely polluted with Cd, Cu, Hg and Zn. The greenhouse and open-field soils had significant difference in Cd, Cr and Zn. The duration of shift from paddy to greenhouse land-use significantly influenced trace metal accumulation with a dramatic change during five to ten year greenhouse land-use, and continuous increase of Cd and Hg. A spatial pattern from north to south for Cd and Hg and a zonal pattern for Cu and Zn were found. An anthropogenic source primarily caused trace metal accumulation, where the principal component analysis/multiple linear regression indicated a contribution 61.2%. While the assessment showed no potential risk for children and adults, the hazard health risks index was greater than one for adolescents. The extended duration of land use as greenhouses caused the trace metal accumulation, rotation in land use should be promoted to reduce the health risks. Copyright © 2016. Published by Elsevier Inc.

Surficial weathering of iron sulfide mine tailings under semi-arid climate.

PubMed

Hayes, Sarah M; Root, Robert A; Perdrial, Nicolas; Maier, Raina; Chorover, Jon

2014-09-15

Mine wastes introduce anthropogenic weathering profiles to the critical zone that often remain unvegetated for decades after mining cessation. As such, they are vulnerable to wind and water dispersion of particulate matter to adjacent ecosystems and residential communities. In sulfide-rich ore tailings, propagation to depth of the oxidative weathering front controls the depth-variation in speciation of major and trace elements. Despite the prevalence of surficial mine waste deposits in arid regions of the globe, few prior studies have been conducted to resolve the near-surface profile of sulfide ore tailings weathered under semi-arid climate. We investigated relations between gossan oxidative reaction-front propagation and the molecular speciation of iron and sulfur in tailings subjected to weathering under semi-arid climate at an EPA Superfund Site in semi-arid central Arizona (USA). Here we report a multi-method data set combining wet chemical and synchrotron-based X-ray diffraction (XRD) and X-ray absorption near-edge spectroscopy (XANES) methods to resolve the tight coupling of iron (Fe) and sulfur (S) geochemical changes in the top 2 m of tailings. Despite nearly invariant Fe and S concentration with depth (130-140 and 100-120 g kg -1 , respectively), a sharp redox gradient and distinct morphological change was observed within the top 0.5 m, associated with a progressive oxidative alteration of ferrous sulfides to (oxyhydr)oxides and (hydroxy)sulfates. Transformation is nearly complete in surficial samples. Trends in molecular-scale alteration were co-located with a decrease in pH from 7.3 to 2.3, and shifts in Fe and S lability as measured via chemical extraction. Initial weathering products, ferrihydrite and gypsum, transform to schwertmannite, then jarosite-group minerals with an accompanying decrease in pH. Interestingly, thermodynamically stable phases such as goethite and hematite were not detected in any samples, but ferrihydrite was observed even in the lowest pH samples, indicating its metastable persistence in these semiarid tailings. The resulting sharp geochemical speciation gradients in close proximity to the tailings surface have important implications for plant colonization, as well as mobility and bioavailability of co-associated toxic metal(loid)s.

Surficial weathering of iron sulfide mine tailings under semi-arid climate

PubMed Central

Hayes, Sarah M.; Root, Robert A.; Perdrial, Nicolas; Maier, Raina; Chorover, Jon

2014-01-01

Mine wastes introduce anthropogenic weathering profiles to the critical zone that often remain unvegetated for decades after mining cessation. As such, they are vulnerable to wind and water dispersion of particulate matter to adjacent ecosystems and residential communities. In sulfide-rich ore tailings, propagation to depth of the oxidative weathering front controls the depth-variation in speciation of major and trace elements. Despite the prevalence of surficial mine waste deposits in arid regions of the globe, few prior studies have been conducted to resolve the near-surface profile of sulfide ore tailings weathered under semi-arid climate. We investigated relations between gossan oxidative reaction-front propagation and the molecular speciation of iron and sulfur in tailings subjected to weathering under semi-arid climate at an EPA Superfund Site in semi-arid central Arizona (USA). Here we report a multi-method data set combining wet chemical and synchrotron-based X-ray diffraction (XRD) and X-ray absorption near-edge spectroscopy (XANES) methods to resolve the tight coupling of iron (Fe) and sulfur (S) geochemical changes in the top 2 m of tailings. Despite nearly invariant Fe and S concentration with depth (130–140 and 100–120 g kg−1, respectively), a sharp redox gradient and distinct morphological change was observed within the top 0.5 m, associated with a progressive oxidative alteration of ferrous sulfides to (oxyhydr)oxides and (hydroxy)sulfates. Transformation is nearly complete in surficial samples. Trends in molecular-scale alteration were co-located with a decrease in pH from 7.3 to 2.3, and shifts in Fe and S lability as measured via chemical extraction. Initial weathering products, ferrihydrite and gypsum, transform to schwertmannite, then jarosite-group minerals with an accompanying decrease in pH. Interestingly, thermodynamically stable phases such as goethite and hematite were not detected in any samples, but ferrihydrite was observed even in the lowest pH samples, indicating its metastable persistence in these semiarid tailings. The resulting sharp geochemical speciation gradients in close proximity to the tailings surface have important implications for plant colonization, as well as mobility and bioavailability of co-associated toxic metal(loid)s. PMID:25197102

Surficial weathering of iron sulfide mine tailings under semi-arid climate

NASA Astrophysics Data System (ADS)

Hayes, Sarah M.; Root, Robert A.; Perdrial, Nicolas; Maier, Raina M.; Chorover, Jon

2014-09-01

Mine wastes introduce anthropogenic weathering profiles to the critical zone that often remain unvegetated for decades after mining cessation. As such, they are vulnerable to wind and water dispersion of particulate matter to adjacent ecosystems and residential communities. In sulfide-rich ore tailings, propagation to depth of the oxidative weathering front controls the depth-variation in speciation of major and trace elements. Despite the prevalence of surficial mine waste deposits in arid regions of the globe, few prior studies have been conducted to resolve the near-surface profile of sulfide ore tailings weathered under semi-arid climate. We investigated relations between gossan oxidative reaction-front propagation and the molecular speciation of iron and sulfur in tailings subjected to weathering in a semi-arid climate at an EPA Superfund Site in central Arizona (USA). Here we report a multi-method data set combining wet chemical and synchrotron-based X-ray diffraction (XRD) and X-ray absorption near-edge spectroscopy (XANES) methods to resolve the tight coupling of iron (Fe) and sulfur (S) geochemical changes in the top 2 m of tailings. Despite nearly invariant Fe and S concentration with depth (130-140 and 100-120 g kg-1, respectively), a sharp redox gradient and distinct morphological change was observed within the top 0.5 m, associated with a progressive oxidative alteration of ferrous sulfides to (oxyhydr)oxides and (hydroxy)sulfates. Transformation is nearly complete in surficial samples. Trends in molecular-scale alteration were co-located with a decrease in pH from 7.3 to 2.3, and shifts in Fe and S lability as measured via chemical extraction. Initial weathering products, ferrihydrite and gypsum, transform to schwertmannite, then jarosite-group minerals with an accompanying decrease in pH. Interestingly, thermodynamically stable phases such as goethite and hematite were not detected in any samples, but ferrihydrite was observed even in samples with the lowest pH, indicating its metastable persistence in these semiarid tailings. The resulting sharp geochemical speciation gradients in close proximity to the tailings surface have important implications for plant colonization, as well as mobility and bioavailability of co-associated toxic metal(loid)s.

Toxic metal(loid) speciation during weathering of iron sulfide mine tailings under semi-arid climate

PubMed Central

Root, Robert A.; Hayes, Sarah M.; Hammond, Corin M.; Maier, Raina M.; Chorover, Jon

2015-01-01

Toxic metalliferous mine-tailings pose a significant health risk to ecosystems and neighboring communities from wind and water dispersion of particulates containing high concentrations of toxic metal(loid)s (e.g., Pb, As, Zn). Tailings are particularly vulnerable to erosion before vegetative cover can be reestablished, i.e., decades or longer in semi-arid environments without intervention. Metal(loid) speciation, linked directly to bioaccessibility and lability, is controlled by mineral weathering and is a key consideration when assessing human and environmental health risks associated with mine sites. At the semi-arid Iron King Mine and Humboldt Smelter Superfund site in central Arizona, the mineral assemblage of the top 2 m of tailings has been previously characterized. A distinct redox gradient was observed in the top 0.5 m of the tailings and the mineral assemblage indicates progressive transformation of ferrous iron sulfides to ferrihydrite and gypsum, which, in turn weather to form schwertmannite and then jarosite accompanied by a progressive decrease in pH (7.3 to 2.3). Within the geochemical context of this reaction front, we examined enriched toxic metal(loid)s As, Pb, and Zn with surficial concentrations 41.1, 10.7, 39.3 mM kg-1 (3080, 2200, and 2570 mg kg-1), respectively. The highest bulk concentrations of As and Zn occur at the redox boundary representing a 1.7 and 4.2 fold enrichment relative to surficial concentrations, respectively, indicating the translocation of toxic elements from the gossan zone to either the underlying redox boundary or the surface crust. Metal speciation was also examined as a function of depth using X-ray absorption spectroscopy (XAS). The deepest sample (180 cm) contains sulfides (e.g., pyrite, arsenopyrite, galena, and sphalerite). Samples from the redox transition zone (25-54 cm) contain a mixture of sulfides, carbonates (siderite, ankerite, cerrusite, and smithsonite) and metal(loid)s sorbed to neoformed secondary Fe phases, principally ferrihydrite. In surface samples (0-35 cm), metal(loid)s are found as sorbed species or incorporated into secondary Fe hydroxysulfate phases, such as schwertmannite and jarosites. Metal-bearing efflorescent salts (e.g., ZnSO4·nH2O) were detected in the surficial sample. Taken together, these data suggest the bioaccessibility and lability of metal(loid)s are altered by mineral weathering, which results in both the downward migration of metal(loid)s to the redox boundary, as well as the precipitation of metal salts at the surface. PMID:26549929

Trace metal characterization of aerosol particles and cloud water during HCCT 2010

NASA Astrophysics Data System (ADS)

Fomba, K. W.; van Pinxteren, D.; Müller, K.; Iinuma, Y.; Lee, T.; Collett, J. L., Jr.; Herrmann, H.

2015-08-01

Trace metal characterization of bulk and size-resolved aerosol and cloud water samples were performed during the Hill Cap Cloud Thuringia (HCCT) campaign. Cloud water was collected at the top of Mt. Schmücke while aerosol samples were collected at two stations upwind and downwind of Mt. Schmücke. Fourteen trace metals including Ti, V, Fe, Mn, Co, Zn, Ni, Cu, As, Sr, Rb, Pb, Cr, and Se were investigated during four full cloud events (FCEs) that fulfilled the conditions of a continuous air mass flow through the three stations. Aerosol particle trace metal concentrations were found to be lower than those observed in the same region during previous field experiments but were within a similar range to those observed in other rural regions in Europe. Fe and Zn were the most abundant elements with concentration ranges of 0.2-111.6 and 1.1-32.1 ng m-3, respectively. Fe, Mn, and Ti were mainly found in coarse mode aerosols while Zn, Pb, and As were mostly found in the fine mode. Correlation and enrichment factor analysis of trace metals revealed that trace metals such as Ti and Rb were mostly of crustal origin while trace metals such as Zn, Pb, As, Cr, Ni, V, and Cu were of anthropogenic origin. Trace metals such as Fe and Mn were of mixed origins including crustal and combustion sources. Trace metal cloud water concentration decreased from Ti, Mn, Cr, to Co with average concentrations of 9.18, 5.59, 5.54, and 0.46 μg L-1, respectively. A non-uniform distribution of soluble Fe, Cu, and Mn was observed across the cloud drop sizes. Soluble Fe and Cu were found mainly in cloud droplets with diameters between 16 and 22 μm, while Mn was found mostly in larger drops greater than 22 μm. Fe(III) was the main form of soluble Fe especially in the small and larger drops with concentrations ranging from 2.2 to 37.1 μg L-1. In contrast to other studies, Fe(II) was observed mainly in the evening hours, implying its presence was not directly related to photochemical processes. Aerosol-cloud interaction did not lead to a marked increase in soluble trace metal concentrations; rather it led to differences in the chemical composition of the aerosol due to preferential loss of aerosol particles through physical processes including cloud drop deposition to vegetative surfaces.

Trace metal characterization of aerosol particles and cloud water during HCCT 2010

NASA Astrophysics Data System (ADS)

Fomba, K. W.; van Pinxteren, D.; Müller, K.; Iinuma, Y.; Lee, T.; Collet, J., Jr.; Herrmann, H.

2015-04-01

Trace metal characterization of bulk and size resolved aerosol and cloud water samples were performed during the Hill Cap Cloud Thuringia (HCCT) campaign. Cloud water was collected at the top of Mt. Schmücke while aerosol samples were collected at two stations upwind and downwind of Mt. Schmücke. Fourteen trace metals including Ti, V, Fe, Mn, Co, Zn, Ni, Cu, As, Sr, Rb, Pb, Cr, and Se were investigated during four full cloud events (FCE) that fulfilled the conditions of a continuous air mass flow through the three stations. Aerosol particle trace metal concentrations were found to be lower than those observed in the same region during previous field experiments but were within a similar range to those observed in other rural regions in Europe. Fe and Zn were the most abundant elements with concentration ranges of 0.2-111.6 and 1.1-32.1 ng m-3, respectively. Fe, Mn and Ti were mainly found in coarse mode aerosols while Zn, Pb and As were mostly found in the fine mode. Correlation and enrichment factor analysis of trace metals revealed that trace metals such as Ti and Rb were mostly of crustal origin while trace metals such as Zn, Pb, As, Cr, Ni, V, and Cu were of anthropogenic origin. Trace metals such as Fe, Mn, were of mixed origins including crustal and combustion sources. Trace metal cloud water concentration decreased from Ti, Mn, Cr, to Co with average concentrations of 9.18, 5.59, 5.54, and 0.46 μg L-1, respectively. A non-uniform distribution of soluble Fe, Cu and Mn was observed across the cloud drop sizes. Soluble Fe and Cu were found mainly in cloud droplets with diameters between 16 and 22 μm while Mn was found mostly in larger drops greater than 22 μm. Fe (III) was the main form of soluble Fe especially in the small and larger drops with concentrations ranging from 2.2 to 37.1 μg L-1. In contrast to other studies, Fe (II) was observed mainly in the evening hours, implying its presence was not directly related to photochemical processes. Aerosol cloud interaction did not lead to a mark increase in soluble trace metal concentrations, but led to differences in the chemical composition of the aerosol due to preferential loss of aerosol particles through physical processes including cloud drop deposition to vegetative surfaces.

Laser-Induced Breakdown Spectroscopy of Trace Metals

NASA Technical Reports Server (NTRS)

Simons, Stephen (Technical Monitor); VanderWal, Randall L.; Ticich, Thomas M.; West, Joseph R., Jr.

2004-01-01

An alternative approach for laser-induced breakdown spectroscopy (LIBS) determination of trace metal determination in liquids is demonstrated. The limits of detection (LOD) for the technique ranged from 10 ppb to 10 ppm for 15 metals metals (Mg, Al, Si, Ca, Ti, Cr, Fe, Co, Ni, Cu, Zn, As, Cd, Hg, Pb) tested.

Metal speciation in soil and health risk due to vegetables consumption in Bangladesh.

PubMed

Islam, Md Saiful; Ahmed, Md Kawser; Habibullah-Al-Mamun, Md

2015-05-01

This study was conducted to investigate the contamination level of heavy metals in soil and vegetables, chemical speciation, and their transfer to the edible part of vegetables. Metals were analyzed using inductively coupled plasma mass spectrometer (ICP-MS). The ranges of Cr, Ni, Cu, As, Cd, and Pb in agricultural soils were 3.7-41, 3.9-36, 3.7-46, 2.3-26, 0.6-13, and 4.5-32 mg/kg, respectively. The metals were predominantly associated with the residual fractions of 39, 41, 40, 40, 34, and 41 % for Cr, Ni, Cu, As, Cd, and Pb, respectively. Considering the metal transfer from soil to the edible part of vegetables, the mean transfer factors (TFs) were in the descending order of Cu > Ni > Cr > Pb > As > Cd. In the edible tissues of vegetables, the concentrations of As, Cd, and Pb in most vegetable samples exceeded the maximum permissible levels, indicating not safe for human consumption. Total target hazard quotient (THQ) of the studied metals (except Cr) from all vegetables were higher than 1, indicated that if people consume these types of vegetables in their diet, they might pose risk to these metals. Total values of carcinogenic risk (CR) were 3.2 for As and 0.15 for Pb which were higher than the US Environmental Protection Agency (USEPA) threshold level (0.000001), indicating that the inhabitants consuming these vegetables are exposed to As and Pb with a lifetime cancer risk.

Estuaries as Filters: The Role of Tidal Marshes in Trace Metal Removal

PubMed Central

Teuchies, Johannes; Vandenbruwaene, Wouter; Carpentier, Roos; Bervoets, Lieven; Temmerman, Stijn; Wang, Chen; Maris, Tom; Cox, Tom J. S.; Van Braeckel, Alexander; Meire, Patrick

2013-01-01

Flux calculations demonstrate that many estuaries are natural filters for trace metals. Yet, the underlying processes are poorly investigated. In the present study, it was hypothesized that intertidal marshes contribute significantly to the contaminant filter function of estuaries. Trace metal concentrations and sediment characteristics were measured along a transect from the subtidal, over an intertidal flat and marsh to a restored marsh with controlled reduced tide. Metal concentrations in the intertidal and restored marsh were found to be a factor two to five higher than values in the subtidal and intertidal flat sediments. High metal concentrations and high accretion rates indicate a high metal accumulation capacity of the intertidal marshes. Overbank sedimentation in the tidal marshes of the entire estuary was calculated to remove 25% to 50% of the riverine metal influx, even though marshes comprise less than 8% of the total surface of the estuary. In addition, the large-scale implementation of planned tidal marsh restoration projects was estimated to almost double the trace metal storage capacity of the present natural tidal marshes in the estuary. PMID:23950927

Comment on "Irreversible sorption of trace concentrations of perfluorocarboxylic acids to fiber filters used for air sampling" by Arp and Goss (Atmospheric Environment 42, 6869-6872, 2008)

NASA Astrophysics Data System (ADS)

Barton, Catherine A.; Kaiser, Mary A.; Butler, Larry E.; Botelho, Miguel A.

This discussion paper reflects concerns as to the technical arguments set forth in the Arp and Goss paper. The authors of the paper, Arp and Goss, hypothesize that vapor phase perfluorocarboxylic acids (PFAs) are irreversibly sorbed to the surface of air sampling filters, and that this sorption erroneously biases vapor/particle speciation measurements toward the particle phase. These authors also suggest a surface treatment of the filters is necessary. As authors of some of the experimental data used in the Arp paper, we believe Arp and Goss have misstated the case for irreversible adsorption, and that untreated filters provide adequate vapor/particle speciation results for PFAs. Additional field data are offered to help prove the point.

Characterization and measurement of natural gas trace constituents. Volume 1. Arsenic. Final report, June 1989-October 1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chao, S.S.; Attari, A.

1995-01-01

The discovery of arsenic compounds, as alkylarsines, in natural gas prompted this research program to develop reliable measurement techniques needed to assess the efficiency of removal processes for these environmentally sensitive substances. These techniques include sampling, speciation, quantitation and on-line instrumental methods for monitoring the total arsenic concentration. The current program has yielded many products, including calibration standards, arsenic-specific sorbents, sensitive analytical methods and instrumentation. Four laboratory analytical methods have been developed and successfully employed for arsenic determination in natural gas. These methods use GC-AED and GC-MS instruments to speciate alkylarsines, and peroxydisulfate extraction with FIAS, special carbon sorbent withmore » XRF and an IGT developed sorbent with GFAA for total arsenic measurement.« less

The effect of abandoned mining ponds on trace elements dynamics in the soil-plant system

NASA Astrophysics Data System (ADS)

Gabarrón, María; Faz, Ángel; Zornoza, Raúl; Acosta, Jose A.

2017-04-01

In semiarid climate regions lack of vegetation and dryer climate contribute to erosion of abandoned mining surface areas making them up important potential sources of metal pollution into the environment. The objectives of this study were to determine the influence of mine ponds in agriculture and forest soils, and identify the dynamic of metals in the soil-plant system for native plant species (Ballota hirsuta) and crop species (Hordeum vulgare) in two ancient mining districts: La Unión and Mazarrón. To achieve these objectives, wastes samples from mine ponds and soil samples (rhizosphere and non-rhizosphere soils) from natural and agricultural lands were collected. In addition, six plants (Ballota hirsuta) from natural area and 3 plants (Hordeum vulgare) from crops were collected. Physicochemical properties and total, water soluble and bioavailable metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) and arsenic were measured in waste/soil samples. The chemical speciation of metals in soil was estimated by a sequential extraction procedure. For plants analyses, each plant were divided in roots, stem and leaves and metal content measured by ICP-MS. Results indicated that mine, natural and agricultural soils were contaminated by As, Cd, Cu, Pb, and Zn. Chemical partitioning revealed higher mobility of metals in mine ponds than natural and agriculture soils while only Fe and As are completely bound to the soil matrix due to the mineralogical compositions of soils. The accumulation of metals in Ballota hirsuta in La Union decrease as Fe>As>Cr>Ni>Cu>Zn>Cd>Mn>Co>Pb while in Mazarrón did as As>Fe>Cr>Pb>Cu>Ni>Co>Mn>Zn>Cd. Ballota hirsuta showed high ability to bio-accumulate Cu, Cr, Fe, Ni, and As, transferring a large amount to edible parts without exceeding the toxicity limits for animals. Results for barley plants (Hordeum vulgare) showed the ability to absorb and accumulate As, Fe, Mn, Pb and Zn, although the transfer ability of As, Cd and Pb was lower. Although the behavior of metals reflects a root barrier effect, the amount of Pb in grain overreached the permissible limit in aliments.

pH-dependent phytoavailability and speciation of tungsten (W) in soil affecting growth and N nutrition of soy (Glycine max)

NASA Astrophysics Data System (ADS)

Oburger, Eva; Vergara Cid, Carolina; Preiner, Julian; Hu, Junjian; Hann, Stephan; Wanek, Wolfgang; Richter, Andreas

2017-04-01

Tungsten (W) is an economically important transition metal that finds a broad scope of applications ranging from household appliances to high-end technology goods. However, in the past decades, increasing industrial and military use of W-based products (particularly ammunition, as well as drilling, milling and cutting tools) opened new pathways of W into natural systems and raise the need for a better understanding of the behavior of W in the environment. Soils play an important role in controlling the bioavailability of pollutants and their entry into the food web via plant uptake as they serve as filter and buffer systems. However, compared to other trace metals, knowledge about the fate of W in the plant-soil environment is rather sketchy. The chemical alikeness of W and molybdenum (Mo) suggests not only similar, typical anionic behaviour in soil but also a potential negative effect of W on important plant physiological processes that require Mo. We examined how soil pH dependent solubility and W speciation affected biomass production, W and nutrient uptake by soy (Glycine max cv Primus) and the activity of molybdoenzymes involved in N assimilation (nitrate reductase) and symbiotic N2 fixation (nitrogenase). Increased solubility of mainly monomeric W in high pH soils resulted in increased W plant uptake, demonstrating a greater risk of entry of W into the food web in alkaline soils. Symbiotic nitrogen fixation was able to compensate for reduced nitrate reductase activity until W soil solution concentrations became too phytotoxic, indicating a more efficient detoxification/compartmentalization mechanism in nodules than in soy leaves. The increasing presence of polymeric W species observed in low pH soils spiked with high W concentrations resulted in decreased W uptake but simultaneously had an overall negative effect on nutrient assimilation and plant growth, suggesting a greater phytotoxicity of W polymers. Our results demonstrate the importance of soil pH for the toxicological behaviour of W in the plant-soil environment, which has been completely ignored in the past.

Investigating Planetesimal Evolution by Experiments with Fe-Ni Metallic Melts: Light Element Composition Effects on Trace Element Partitioning Behavior

NASA Astrophysics Data System (ADS)

Chabot, N. L.

2017-12-01

As planetesimals were heated up in the early Solar System, the formation of Fe-Ni metallic melts was a common occurrence. During planetesimal differentiation, the denser Fe-Ni metallic melts separated from the less dense silicate components, though some meteorites suggest that their parent bodies only experienced partial differentiation. If the Fe-Ni metallic melts did form a central metallic core, the core eventually crystallized to a solid, some of which we sample as iron meteorites. In all of these planetesimal evolution processes, the composition of the Fe-Ni metallic melt influenced the process and the resulting trace element chemical signatures. In particular, the metallic melt's "light element" composition, those elements present in the metallic melt in a significant concentration but with lower atomic masses than Fe, can strongly affect trace element partitioning. Experimental studies have provided critical data to determine the effects of light elements in Fe-Ni metallic melts on trace element partitioning behavior. Here I focus on combining numerous experimental results to identify trace elements that provide unique insight into constraining the light element composition of early Solar System Fe-Ni metallic melts. Experimental studies have been conducted at 1 atm in a variety of Fe-Ni systems to investigate the effects of light elements on trace element partitioning behavior. A frequent experimental examination of the effects of light elements in metallic systems involves producing run products with coexisting solid metal and liquid metal phases. Such solid-metal-liquid-metal experiments have been conducted in the Fe-Ni binary system as well as Fe-Ni systems with S, P, and C. Experiments with O-bearing or Si-bearing Fe-Ni metallic melts do not lend themselves to experiments with coexisting solid metal and liquid metal phases, due to the phase diagrams of these elements, but experiments with two immiscible Fe-Ni metallic melts have provided insight into the qualitative effects of O and Si relative to the well-determined effects of S. Together, these experimental studies provide a robust dataset to identify key elements that are predicted to produce distinct chemical signatures as a function of different Fe-Ni metallic melt compositions during planetesimal evolution processes.

Total and water-soluble trace metal content of urban background PM 10, PM 2.5 and black smoke in Edinburgh, UK

NASA Astrophysics Data System (ADS)

Heal, Mathew R.; Hibbs, Leon R.; Agius, Raymond M.; Beverland, Iain J.

Toxicological studies have implicated trace metals in airborne particles as possible contributors to respiratory and/or cardiovascular inflammation. As part of an epidemiological study, co-located 24 h samples of PM 10, PM 2.5 and black smoke (BS) were collected for 1 year at an urban background site in Edinburgh, and each sample sequentially extracted with ultra-pure water, then concentrated HNO 3/HCl, and analysed for Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd and Pb. This yields a comprehensive data set for UK urban airborne trace metal. The median ( n>349) daily water-soluble metal concentration in PM 2.5 ranged from 0.05 ng m -3 for Ti to 5.1 ng m -3 for Pb; and in PM 10 from 0.18 ng m -3 for Ti to 11.7 ng m -3 for Fe. Median daily total (i.e. water+acid-extractable) metal concentration in PM 2.5 ranged from 0.3 ng m -3 for As to 27.6 ng m -3 for Fe; and in PM 10 from 0.37 ng m -3 for As to 183 ng m -3 for Fe. The PM 2.5:PM 10 ratio varied considerably with metal, from <17%, on average, for Ti and Fe, to >70% for V, As, Cd and Pb. The 11 trace metals constituted proportionally more of the PM 10-2.5 fraction than of the PM 2.5 fraction (0.9%). The proportion of water-soluble metal in each size-fraction varied considerably, from <10% water-soluble Fe and Ti in PM 10-2.5, to >50% water-soluble V, Zn, As and Cd in PM 2.5. Although Fe generally dominated the trace metal, water-soluble metal also contained significant Zn, Pb and Cu, and for all size and solubility fractions >90% of trace metal was comprised of Fe, Zn, Pb and Cu. Statistical analyses suggested three main sources: traffic; static combustion; and crustal. The association of metals with traffic (Cu, Fe, Mn, Pb, Zn) was consistent with traffic-induced non-exhaust "resuspension" rather than direct exhaust emission. Meteorology contributed to the wide variation in daily trace metal concentration. The proportion of trace metal in particles varied significantly with the air mass source and was highest on days for trajectories traversing over land. For Mn, Fe, Cu, Zn, As and Pb there was greater correlation of metal concentration with BS mass than with either PM 10 or PM 2.5 mass, suggesting that BS reflectance monitoring could be a cost-effective surrogate measure of particle metal concentration in urban background air.

Mercury transformation and speciation in flue gases from anthropogenic emission sources: a critical review

NASA Astrophysics Data System (ADS)

Zhang, Lei; Wang, Shuxiao; Wu, Qingru; Wang, Fengyang; Lin, Che-Jen; Zhang, Leiming; Hui, Mulin; Yang, Mei; Su, Haitao; Hao, Jiming

2016-02-01

Mercury transformation mechanisms and speciation profiles are reviewed for mercury formed in and released from flue gases of coal-fired boilers, non-ferrous metal smelters, cement plants, iron and steel plants, waste incinerators, biomass burning and so on. Mercury in coal, ores, and other raw materials is released to flue gases in the form of Hg0 during combustion or smelting in boilers, kilns or furnaces. Decreasing temperature from over 800 °C to below 300 °C in flue gases leaving boilers, kilns or furnaces promotes homogeneous and heterogeneous oxidation of Hg0 to gaseous divalent mercury (Hg2+), with a portion of Hg2+ adsorbed onto fly ash to form particulate-bound mercury (Hgp). Halogen is the primary oxidizer for Hg0 in flue gases, and active components (e.g., TiO2, Fe2O3, etc.) on fly ash promote heterogeneous oxidation and adsorption processes. In addition to mercury removal, mercury transformation also occurs when passing through air pollution control devices (APCDs), affecting the mercury speciation in flue gases. In coal-fired power plants, selective catalytic reduction (SCR) system promotes mercury oxidation by 34-85 %, electrostatic precipitator (ESP) and fabric filter (FF) remove over 99 % of Hgp, and wet flue gas desulfurization system (WFGD) captures 60-95 % of Hg2+. In non-ferrous metal smelters, most Hg0 is converted to Hg2+ and removed in acid plants (APs). For cement clinker production, mercury cycling and operational conditions promote heterogeneous mercury oxidation and adsorption. The mercury speciation profiles in flue gases emitted to the atmosphere are determined by transformation mechanisms and mercury removal efficiencies by various APCDs. For all the sectors reviewed in this study, Hgp accounts for less than 5 % in flue gases. In China, mercury emission has a higher Hg0 fraction (66-82 % of total mercury) in flue gases from coal combustion, in contrast to a greater Hg2+ fraction (29-90 %) from non-ferrous metal smelting, cement and iron and/or steel production. The higher Hg2+ fractions shown here than previous estimates may imply stronger local environmental impacts than previously thought, caused by mercury emissions in East Asia. Future research should focus on determining mercury speciation in flue gases from iron and steel plants, waste incineration and biomass burning, and on elucidating the mechanisms of mercury oxidation and adsorption in flue gases.

Mercury transformation and speciation in flue gases from anthropogenic emission sources: a critical review

NASA Astrophysics Data System (ADS)

Zhang, L.; Wang, S. X.; Wu, Q. R.; Wang, F. Y.; Lin, C.-J.; Zhang, L. M.; Hui, M. L.; Hao, J. M.

2015-11-01

Mercury transformation mechanisms and speciation profiles are reviewed for mercury formed in and released from flue gases of coal-fired boilers, non-ferrous metal smelters, cement plants, iron and steel plants, municipal solid waste incinerators, and biomass burning. Mercury in coal, ores and other raw materials is released to flue gases in the form of Hg0 during combustion or smelting in boilers, kilns or furnaces. Decreasing temperature from over 800 °C to below 300 °C in flue gases leaving boilers, kilns or furnaces promotes homogeneous and heterogeneous oxidation of gaseous elemental mercury (Hg0) to gaseous divalent mercury (Hg2+), with a portion of Hg2+ adsorbed onto fly ash to form particulate-bound mercury (Hgp). Halogen is the primary oxidizer for Hg0 in flue gases, and active components (e.g.,TiO2, Fe2O3, etc.) on fly ash promote heterogeneous oxidation and adsorption processes. In addition to mercury removal, mercury transformation also occurs when passing through air pollution control devices (APCDs), affecting the mercury speciation in flue gases. In coal-fired power plants, selective catalytic reduction (SCR) system promotes mercury oxidation by 34-85 %, electrostatic precipitator (ESP) and fabric filter (FF) remove over 99 % of Hgp, and wet flue gas desulfurization system (WFGD) captures 60-95 % of Hg2+. In non-ferrous metal smelters, most Hg0 is converted to Hg2+ and removed in acid plants (APs). For cement clinker production, mercury cycling and operational conditions promote heterogeneous mercury oxidation and adsorption. The mercury speciation profiles in flue gases emitted to the atmosphere are determined by transformation mechanisms and mercury removal efficiencies by various APCDs. For all the sectors reviewed in this study, Hgp accounts for less than 5 % in flue gases. In China, mercury emission has a higher fraction (66-82 % of total mercury) in flue gases from coal combustion, in contrast to a greater Hg2+ fraction (29-90 %) from non-ferrous metal smelting, cement and iron/steel production. The higher Hg2+ fractions shown here than previous estimates may imply stronger local environmental impacts than previously thought, caused by mercury emissions in East Asia. Future research should focus on determining mercury speciation in flue gases from iron and steel plants, waste incineration and biomass burning, and on elucidating the mechanisms of mercury oxidation and adsorption in flue gases.

Whole rock and discrete pyrite geochemistry as complementary tracers of ancient ocean chemistry: An example from the Neoproterozoic Doushantuo Formation, China

NASA Astrophysics Data System (ADS)

Gregory, Daniel D.; Lyons, Timothy W.; Large, Ross R.; Jiang, Ganqing; Stepanov, Aleksandr S.; Diamond, Charles W.; Figueroa, Maria C.; Olin, Paul

2017-11-01

The trace element content of pyrite is a recently developed proxy for metal abundance in paleo-oceans. Previous studies have shown that the results broadly match those of whole rock studies through geologic time. However, no detailed study has evaluated the more traditional proxies for ocean chemistry for comparison to pyrite trace element data from the same samples. In this study we compare pyrite trace element data from 14 samples from the Wuhe section of the Ediacaran-age Doushantuo Formation, south China, measured by laser ablation inductively coupled plasma mass spectrometry with new and existing whole rock trace element concentrations; total organic carbon; Fe mineral speciation; S isotope ratios; and pyrite textural relationships. This approach allows for comparison of data for individual trace elements within the broader environmental context defined by the other chemical parameters. The results for discrete pyrite analyses show that several chalcophile and siderophile elements (Ag, Sb, Se, Pb, Cd, Te, Bi, Mo, Ni, and Au) vary among the samples with patterns that mirror those of the independent whole rock data. A comparison with existing databases for sedimentary and hydrothermal pyrite allows us to discriminate between signatures of changing ocean conditions and those of known hydrothermal sources. In the case of the Wuhe samples, the observed patterns for trace element variation point to primary marine controls rather than higher temperature processes. Specifically, our new data are consistent with previous arguments for pulses of redox sensitive trace elements interpreted to be due to marine oxygenation against a backdrop of mostly O2-poor conditions in the Ediacaran ocean-with important implications for the availability of bioessential elements. The agreement between the pyrite and whole rock data supports the use of trace element content of pyrite as a tracer of ocean chemistry in ways that complement existing approaches, while also opening additional windows of opportunity. For example, unlike the potential vulnerability of whole rock data to secondary alteration, the pyrite record may survive greenschist facies metamorphism. Furthermore, early-formed pyrite can be identified through textural relationships as a proxy of primary marine chemistry even in the presence of hydrothermal overprints on whole rock chemistry via secondary fluids. Finally, pyrite analyses may allow for the possibility of more quantitative interpretations of the ancient ocean once the elemental partitioning between the mineral and host fluids are better constrained. Collectively, these advances can greatly increase the number of basins that may be investigated for early ocean chemistry, especially those of Precambrian age.

Evidence of historical mining inferred from metal concentration of alluvial sediments in the Bernese Alps

NASA Astrophysics Data System (ADS)

Carvalho, Filipe; Schulte, Lothar

2017-04-01

Metal pollution is normally associated with modern day industrialization. However, evidences of anthropogenic metal pollution date back to the Palaeolithic, were the domestication of fire contributed to an increase of trace metals released from the burning wood. Large-scale metal pollution started during the Roman period with the increase of mining and smelting activities. The production of metals during this period was quite rudimentary and highly polluting, contributing to a raise of metal concentrations in the atmosphere and subsequently in sediments and soils. Towards the modern period, production methods were improved, especially since the industrial revolution, but continued to release pollutants to the environment. The aim of this study is to identify periods of increased mining activity though the analysis of sedimentary records. For this purpose, we study the geochemical response of trace metals in sedimentary cores from the Aare and Lütschine delta plains, located at the Bernese Alps. The focus of this analysis is the detection of metal concentration anomalies from the last 3000 years. The analysis is based on the X-Ray Fluorescence (AVATECH XRF core scanner) response of the chemical elements copper (Cu), zinc (Zn) and lead (Pb) contained in eight cores with depths down to 10 meter. All data was filtered in order to remove the noise from natural processes such as the increase of trace metal concentrations in organic rich horizons and to select the highest peaks of these metals. Results show similar trends in all the analysed cores and indicate three major pulses of trace metal concentration during the Roman Period, Early Medieval Age and a general increase of metal concentration during the Modern era, which can evidence mining and smelting activities. Periods of lower trace metal concentrations and shifts in concentration trends relate accurately with central Europe social and economic transitions, migratory events and significant demographic variations. It is also possible to identify some trace metal peaks during the late Neolithic period. The findings of archaeological sites from this region support the assumption of these possible early pollution periods.

Recent Developments in Copper and Zinc Homeostasis in Bacterial Pathogens

PubMed Central

Braymer, Joseph J.; Giedroc, David P.

2014-01-01

Copper and zinc homeostasis systems in pathogenic bacteria are required to resist host efforts to manipulate the availability and toxicity of these metal ions. Central to this microbial adaptive response is the involvement of metal-trafficking and -sensing proteins that ultimately exercise control of metal speciation in the cell. Cu- and Zn-specific metalloregulatory proteins regulate the transcription of metal-responsive genes while metallochaperones and related proteins ensure that these metals are appropriately buffered by the intracellular milieu and delivered to correct intracellular targets. In this review, we summarize recent findings on how bacterial pathogens mount a metal-specific response to derail host efforts to win the “fight over metals.” PMID:24463765

Selective speciation improves efficacy and lowers toxicity of platinum anticancer and vanadium antidiabetic drugs.

PubMed

Doucette, Kaitlin A; Hassell, Kelly N; Crans, Debbie C

2016-12-01

Improving efficacy and lowering resistance to metal-based drugs can be addressed by consideration of the coordination complex speciation and key reactions important to vanadium antidiabetic drugs or platinum anticancer drugs under biological conditions. The methods of analyses vary depending on the specific metal ion chemistry. The vanadium compounds interconvert readily, whereas the reactions of the platinum compounds are much slower and thus much easier to study. However, the vanadium species are readily differentiated due to vanadium complexes differing in color. For both vanadium and platinum systems, understanding the processes as the compounds, Lipoplatin and Satraplatin, enter cells is needed to better combat the disease; there are many cellular metabolites, which may affect processing and thus the efficacy of the drugs. Examples of two formulations of platinum compounds illustrate how changing the chemistry of the platinum will result in less toxic and better tolerated drugs. The consequence of the much lower toxicity of the drug, can be readily realized because cisplatin administration requires hospital stay whereas Lipoplatin can be done in an outpatient manner. Similarly, the properties of Satraplatin allow for development of an oral drug. These forms of platinum demonstrate that the direct consequence of more selective speciation is lower side effects and cheaper administration of the anticancer agent. Therefore we urge that as the community goes forward in development of new drugs, control of speciation chemistry will be considered as one of the key strategies in the future development of anticancer drugs. Copyright © 2016 Elsevier Inc. All rights reserved.

Influence of environmental conditions on the toxicokinetics of cadmium in the marine copepod Acartia tonsa.

PubMed

Pavlaki, Maria D; Morgado, Rui G; van Gestel, Cornelis A M; Calado, Ricardo; Soares, Amadeu M V M; Loureiro, Susana

2017-11-01

mMarine and estuarine ecosystems are highly productive areas that often act as a final sink for several pollutants, such as cadmium. Environmental conditions in these habitats can affect metal speciation, as well as its uptake and depuration by living organisms. The aim of this study was to assess cadmium uptake and depuration rates in the euryhaline calanoid copepod Acartia tonsa under different pH, salinity and temperature conditions. Cadmium speciation did not vary with changing pH or temperature, but varied with salinity. Free Cd 2+ ion activity increased with decreasing salinities resulting in increased cadmium concentrations in A. tonsa. However, uptake rate, derived using free Cd 2+ ion activity, showed no significant differences at different salinities indicating a simultaneous combined effect of Cd 2+ speciation and metabolic rates for osmoregulation. Cadmium concentration in A. tonsa and uptake rate increased with increasing pH, showing a peak at the intermediate pH of 7.5, while depuration rate fluctuated, thus suggesting that both parameters are mediated by metabolic processes (to maintain homeostasis at pH levels lower than normal) and ion competition at membrane binding sites. Cadmium concentration in A. tonsa, uptake and depuration rates increased with increasing temperature, a trend that can be attributed to an increase in metabolic energy demand at higher temperatures. The present study shows that cadmium uptake and depuration rates in the marine copepod A. tonsa is mostly affected by biological processes, mainly driven by metabolic mechanisms, and to a lesser extent by metal speciation in the exposure medium. Copyright © 2017 Elsevier Inc. All rights reserved.

Trace metals partitioning between particulate and dissolved phases along a tropical mangrove estuary (Can Gio, Vietnam).

PubMed

Thanh-Nho, Nguyen; Strady, Emilie; Nhu-Trang, Tran-Thi; David, Frank; Marchand, Cyril

2018-04-01

Mangroves can be considered as biogeochemical reactors along (sub)tropical coastlines, acting both as sinks or sources for trace metals depending on environmental factors. In this study, we characterized the role of a mangrove estuary, developing downstream a densely populated megacity (Ho Chi Minh City, Vietnam), on the fate and partitioning of trace metals. Surface water and suspended particulate matter were collected at four sites along the estuarine salinity gradient during 24 h cycling in dry and rainy seasons. Salinity, pH, DO, TSS, POC, DOC, dissolved and particulate Fe, Mn, Cr, As, Cu, Ni, Co and Pb were measured. TSS was the main trace metals carrier during their transit in the estuary. However, TSS variations did not explain the whole variability of metals distribution. Mn, Cr and As were highly reactive metals while the other metals (Fe, Ni, Cu, Co and Pb) presented stable log K D values along the estuary. Organic matter dynamic appeared to play a key role in metals fractioning. Its decomposition during water transit in the estuary induced metal desorption, especially for Cr and As. Conversely, dissolved Mn concentrations decreased along the estuary, which was suggested to result from Mn oxidative precipitation onto solid phase due to oxidation and pH changes. Extra sources as pore-water release, runoff from adjacent soils, or aquaculture effluents were suggested to be involved in trace metal dynamic in this estuary. In addition, the monsoon increased metal loads, notably dissolved and particulate Fe, Cr, Ni and Pb. Copyright © 2018 Elsevier Ltd. All rights reserved.

Method for removing trace pollutants from aqueous solutions

DOEpatents

Silver, G.L.

A method of substantially removing a trace metallic contaminant from a liquid containing the same comprises: adding an oxidizing agent to a liquid containing a trace amount of a metallic contaminant of a concentration of up to about 0.1 ppM, and separating the homogeneously precipitated product from the liquid.

Vegetation and Cold Trapping Modulating Elevation-dependent Distribution of Trace Metals in Soils of a High Mountain in Eastern Tibetan Plateau

PubMed Central

Bing, Haijian; Wu, Yanhong; Zhou, Jun; Li, Rui; Luo, Ji; Yu, Dong

2016-01-01

Trace metals adsorbed onto fine particles can be transported long distances and ultimately deposited in Polar Regions via the cold condensation effect. This study indicated the possible sources of silver (Ag), cadmium (Cd), copper (Cu), lead (Pb), antimony (Sb) and zinc (Zn) in soils on the eastern slope of Mt. Gongga, eastern Tibetan Plateau, and deciphered the effects of vegetation and mountain cold condensation on their distributions with elevation. The metal concentrations in the soils were comparable to other mountains worldwide except the remarkably high concentrations of Cd. Trace metals with high enrichment in the soils were influenced from anthropogenic contributions. Spatially, the concentrations of Cu and Zn in the surface horizons decreased from 2000 to 3700 m a.s.l., and then increased with elevation, whereas other metals were notably enriched in the mid-elevation area (approximately 3000 m a.s.l.). After normalization for soil organic carbon, high concentrations of Cd, Pb, Sb and Zn were observed above the timberline. Our results indicated the importance of vegetation in trace metal accumulation in an alpine ecosystem and highlighted the mountain cold trapping effect on trace metal deposition sourced from long-range atmospheric transport. PMID:27052807

Humic substances and trace metals associated with Fe and Al oxides deposited in an acidic mountain stream

USGS Publications Warehouse

McKnight, Diane M.; Wershaw, R. L.; Bencala, K.E.; Zellweger, G.W.; Feder, G.L.

1992-01-01

Hydrous iron and aluminum oxides are deposited on the streambed in the confluence of the Snake River and Deer Creek, two streams in the Colorado Rocky Mountains. The Snake River is acidic and has high concentrations of dissolved Fe and Al. These metals precipitate at the confluence with the pristine, neutral pH, Deer Creek because of the greater pH (4.5-6.0) in the confluence. The composition of the deposited oxides changes consistently with distance downstream, with the most upstream oxide samples having the greatest Fe and organic carbon content. Fulvic acid accounts for most of the organic content of the oxides. Results indicate that streambed oxides in the confluence are not saturated with respect to their capacity to sorb dissolved humic substances from streamwater. The contents of several trace metals (Mn, Zn, Cu, Pb, Ni and Co) also decrease with distance downstream and are correlated with both the Fe and organic carbon contents. Strong metal-binding sites associated with the sorbed fulvic acid are more than sufficient to account for the trace metal content of the oxides. Complexation of trace metals by sorbed fulvic acid may explain the observed downstream decrease in trace metal content.

Chromium in urban sediment particulates: an integrated micro-chemical and XANES study

NASA Astrophysics Data System (ADS)

Taylor, Kevin; Byrne, Patrick; Hudson-Edwards, Karen

2015-04-01

Chromium is generally common within the urban sediment cascade as a result of abundant industrial and transport-related sources. The risks that Cr-bearing particles pose to ecosystems and humans depend on the solid phase chemical speciation of Cr in the particles. In this study, we use bulk chemical digests, sequential chemical extraction analysis, electron microscopy, electron microprobe and microfocus XANES analysis to describe the solid-phase speciation of Cr in urban particulate matter from both aquatic sediment and road dust sediment (RDS) in Manchester, UK. Cr-bearing grains within RDS are predominantly iron oxide grains, commonly of goethite or haematite mineralogy, but Cr-bearing silicate glass grains are also present. Iron oxide glass grains most likely have sorbed Cr, and derive from the rusting of Cr-steel particles from vehicles. Electron microprobe analysis indicates concentrations of Cr up to 3200 μg/g in these grains, and XANES analysis indicates that Cr(III) is the dominant oxidation state, with some trace amounts of Cr(VI). Cr-bearing grains within aquatic sediments are dominated by alumino-silicate glass grains derived from industrial waste. These grains contain Cr-rich areas with up to 19% Cr2O3 and XANES analysis indicates that Cr is present as Cr(III). The dominance of Cr(III) in these urban particulate grains suggests limited bioavailability or toxicity. However, the presence within two markedly different grain types (iron oxides and silicate glasses) indicates that the long-term geochemical behaviour and environmental risk of RDS and the aquatic sediments studied are likely to be quite different. These findings highlight the importance of understanding sources of metal contaminants in urban environments and the geochemical processes that affect their transfer through the urban sediment cascade and the wider river basin.

Effects of conversion of mangroves into gei wai ponds on sediment heavy metals accumulation in tidal flat estuary, South China

NASA Astrophysics Data System (ADS)

Li, R.; Qiu, G.; Chai, M.; Li, R.

2017-12-01

Gei wai ponds act as important component in mangrove ecosystem, but the conversion of mangroves into gei wai ponds and its ecological function on heavy metal accumulation is still not clear. The study quantified the sediment heavy metal concentration and speciation in gei wai pond, Avicennia marina marsh and mudflat in Futian mangrove wetlands, South China. The results showed that gei wai pond acidified the sediment and reduced its fertility due to reduced pH, electronic conductivity (EC) and total organic carbon (TOC) compared to A. marina marsh and mudflat. The concentrations of Cd, Cu, Zn and Pb at all depth in gei wai pond sediment were also lower than other sites, indicating reduced storage function on heavy metals. Multiple analysis implied that heavy metals in all sites could be attributed to anthropogenic sources, with Cr as natural and anthropogenic sources in gei wai pond. Gei wai pond sediment had lower heavy metal pollution based on multiple evaluation methods, including potential ecological risk coefficient (Eir), potential ecological risk index (RI), geo-accumulation index (Igeo), mean PEL quotients (m-PEL-q), pollution load index (PLI), mean ERM quotients (m-ERM-q) and total toxic unit (∑TU). Heavy metal speciation analysis indicated that gei wai pond improved the conversion from the immobilized Cd and Cr to the mobilized fraction. SEM-AVS analysis indicated no adverse toxicity occurred in all sites, and the role of TOC in relieving sediment heavy metal toxicity of gei wai pond is limited.

Characterization of changes in floc morphology, extracellular polymeric substances and heavy metals speciation of anaerobically digested biosolid under treatment with a novel chelated-Fe2+ catalyzed Fenton process.

PubMed

He, Juanjuan; Yang, Peng; Zhang, Weijun; Cao, Bingdi; Xia, Hua; Luo, Xi; Wang, Dongsheng

2017-11-01

A novel chelated-Fe 2+ catalyzed Fenton process (CCFP) was developed to enhance dewatering performance of anaerobically digested biosolid, and changes in floc morphology, extracellular polymeric substances (EPS) and heavy metals speciation were also investigated. The results showed that addition of chelating agents caused EPS solubilization by binding multivalent cations. Like traditional Fenton, CCFP performed well in improving anaerobically digested sludge dewatering property. The highly active radicals (OH, O 2 - ) produced in classical Fenton and CCFP were responsible for sludge flocs destruction and consequently degradation of biopolymers into small molecules. Furthermore, more plentiful pores and channels were presented in cake after Fenton treatment, which was conducive to water drainage under mechanical compression. Additionally, a portion of active heavy metals in the form of oxidizable and reducible states were dissolved under CCFP. Therefore, CCFP could greatly simplify the operating procedure of Fenton conditioning and improve its process adaptability for harmless treatment of biological sludge. Copyright © 2017 Elsevier Ltd. All rights reserved.

Environmental and Ecological Risk Assessment of Trace Metal Contamination in Mangrove Ecosystems: A Case from Zhangjiangkou Mangrove National Nature Reserve, China

PubMed Central

Wang, Jun; Du, Huihong; Xu, Ye; Chen, Kai; Liang, Junhua; Ke, Hongwei; Cheng, Sha-Yen; Liu, Mengyang; Deng, Hengxiang; He, Tong; Wang, Wenqing

2016-01-01

Zhangjiangkou Mangrove National Nature Reserve is a subtropical wetland ecosystem in southeast coast of China, which is of dense population and rapid development. The concentrations, sources, and pollution assessment of trace metals (Cu, Cd, Pb, Cr, Zn, As, and Hg) in surface sediment from 29 sites and the biota specimen were investigated for better ecological risk assessment and environmental management. The ranges of trace metals in mg/kg sediment were as follows: Cu (10.79–26.66), Cd (0.03–0.19), Pb (36.71–59.86), Cr (9.67–134.51), Zn (119.69–157.84), As (15.65–31.60), and Hg (0.00–0.08). The sequences of the bioaccumulation of studied metals are Zn > Cu > As > Cr > Pb > Cd > Hg with few exceptions. Cluster analysis and principal component analysis revealed that the trace metals in the studied area mainly derived from anthropogenic activities, such as industrial effluents, agricultural waste, and domestic sewage. Pollution load index and geoaccumulation index were calculated for trace metals in surface sediments, which indicated unpolluted status in general except Pb, Cr, and As. PMID:27795956

Spatial variability and temporal changes in the trace metal content of soils: implications for mine restoration plan.

PubMed

Chandra, Rachna; Prusty, B Anjan Kumar; Azeez, P A

2014-06-01

Trace metals in soils may be inherited from the parent materials or added to the system due to anthropogenic activities. In proposed mining areas, trace metals become an integral part of the soil system. Usually, researchers undertake experiments on plant species selection (for the restoration plan) only after the termination of mining activities, i.e. without any pre-mining information about the soil-plant interactions. Though not shown in studies, it is clear that several recovery plans remain unsuccessful while carrying out restoration experiments. Therefore, we hypothesize that to restore the area effectively, it is imperative to consider the pre-mining scenario of metal levels in parent material as well as the vegetation ecology of the region. With these specifics, we examined the concentrations of trace metals in parent soils at three proposed bauxite locations in the Eastern Ghats, India, and compared them at a spatio-temporal scale. Vegetation quantification and other basic soil parameters accounted for establishing the connection between soil and plants. The study recorded significant spatial heterogeneity in trace metal concentrations and the role of vegetation on metal availability. Oxidation reduction potential (ORP), pH and cation exchange capacity (CEC) directly influenced metal content, and Cu and Ni were lithogenic in origin. It implies that for effective restoration plant species varies for each geological location.

Macroscopic and spectroscopic investigations on Eu(III) and Cm(III) sorption onto bayerite (β-Al(OH)3) and corundum (α-Al2O3).

PubMed

Kupcik, Tomas; Rabung, Thomas; Lützenkirchen, Johannes; Finck, Nicolas; Geckeis, Horst; Fanghänel, Thomas

2016-01-01

The interaction of trivalent Cm and Eu with the aluminum hydroxide bayerite (β-Al(OH)3) and the aluminum oxide corundum (α-Al2O3) was investigated by batch sorption experiments and time resolved laser fluorescence spectroscopy (TRLFS). The experimental methods for both polymorphs show similar pH dependent sorption behavior at trace metal ion concentrations (∼10(-7) M), i.e. similar Eu sorption edges and nearly identical Cm speciation between pH=3 and 13. In this pH range the Cm aquo ion as well as the Cm(III) surface species surface⋯Cm(OH)x(H2O)(5-x) (x=0, 1, 2) can be distinguished by TRLFS. The similar sorption data point to a (surface) transformation of the thermodynamically unstable Al2O3 surface into bayerite, in agreement with the similar isoelectric points obtained for both minerals (pH(IEP)=8.6-8.8). The pH dependent surface charge is most likely due to the protonation/deprotonation of singly coordinated Al-OH surface groups, prevailing on the edge planes of the rod-like bayerite crystals and the surface of the colloidal Al2O3 particles. These surface groups are also believed to act as ligands for lanthanide/actinide(III) surface complexation. In contrast to the similar sorption behavior at trace metal ion concentrations, discrepancies are observed at higher Eu levels. While similar sorption edges occur up to 7×10(-7) M Eu for corundum, the pH edge on bayerite is gradually shifted to higher pH values in this Eu concentration range. The latter behavior may be related either to the existence of multiple sorption sites with different sorption affinities, or to the influence of an additional amorphous Al-phase, forming in the course of the bayerite synthesis. Copyright © 2015 Elsevier Inc. All rights reserved.

Aluminum binding by humus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benedetti, M.F.; Hiemstra, T.; Riemsdijk, W. van

The need for qualitative and quantitative description of the chemical speciation of Al, in particular and other metal ions in general, is stressed by the increased mobilization of metal ions in water and soils due to acid rain deposition. In this paper we present new data of Al binding to two humic acids. These new data sets and the some previously published data will be analyzed with the NICA-Donnan model using one set of parameters to describe the Al binding to the different humic substances. Once the experimental data is described with the NICA-Donnan approach, we will show the effectmore » of Ca on Al binding and surface speciation as well as the effect of Al on the charge of the humic particles. The parameters derived from the laboratory experiments will be used to describe the variation of the field based Al partition coefficient.« less

Polynuclear Speciation of Trivalent Cations near the Surface of an Electrolyte Solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bera, Mrinal K.; Antonio, Mark R.

Despite long-standing efforts, there is no agreed upon structural model for electrolyte solutions at air-liquid interfaces. We report the simultaneous detection of the near-surface and bulk coordination environments of a trivalent metal cation (europium) in an aqueous solution by use of X-ray absorption spectroscopy. Within the first few nanometers of the liquid surface, the cations exhibit oxygen coordination typical of inner-sphere hydration of an aquated Eu3+ cation. Beyond that, outer-sphere ion-ion correlations are observed that are otherwise not present in the bulk electrolyte. The combination of near-surface and bulk sensitivities to probe metal ion speciation in electrolyte solutions is achievedmore » by detecting electron-yield and X-ray fluorescence signals from an inverted pendant drop. The results provide new knowledge about the near-surface chemistry of aqueous solutions of relevance to aerosols and ion transport processes in chemical separations and biological systems.« less

Foliar or root exposures to smelter particles: consequences for lead compartmentalization and speciation in plant leaves.

PubMed

Schreck, Eva; Dappe, Vincent; Sarret, Géraldine; Sobanska, Sophie; Nowak, Dorota; Nowak, Jakub; Stefaniak, Elżbieta Anna; Magnin, Valérie; Ranieri, Vincent; Dumat, Camille

2014-04-01

In urban areas with high fallout of airborne particles, metal uptake by plants mainly occurs by foliar pathways and can strongly impact crop quality. However, there is a lack of knowledge on metal localization and speciation in plants after pollution exposure, especially in the case of foliar uptake. In this study, two contrasting crops, lettuce (Lactuca sativa L.) and rye-grass (Lolium perenne L.), were exposed to Pb-rich particles emitted by a Pb-recycling factory via either atmospheric or soil application. Pb accumulation in plant leaves was observed for both ways of exposure. The mechanisms involved in Pb uptake were investigated using a combination of microscopic and spectroscopic techniques (electron microscopy, laser ablation, Raman microspectroscopy, and X-ray absorption spectroscopy). The results show that Pb localization and speciation are strongly influenced by the type of exposure (root or shoot pathway) and the plant species. Foliar exposure is the main pathway of uptake, involving the highest concentrations in plant tissues. Under atmospheric fallouts, Pb-rich particles were strongly adsorbed on the leaf surface of both plant species. In lettuce, stomata contained Pb-rich particles in their apertures, with some deformations of guard cells. In addition to PbO and PbSO4, chemical forms that were also observed in pristine particles, new species were identified: organic compounds (minimum 20%) and hexagonal platy crystals of PbCO3. In rye-grass, the changes in Pb speciation were even more egregious: Pb-cell wall and Pb-organic acid complexes were the major species observed. For root exposure, identified here as a minor pathway of Pb transfer compared to foliar uptake, another secondary species, pyromorphite, was identified in rye-grass leaves. Finally, combining bulk and spatially resolved spectroscopic techniques permitted both the overall speciation and the minor but possibly highly reactive lead species to be determined in order to better assess the health risks involved. Copyright © 2013 Elsevier B.V. All rights reserved.

National Trends in Trace Metals Concentrations in Ambient Particulate Matter

NASA Astrophysics Data System (ADS)

McCarthy, M. C.; Hafner, H. R.; Charrier, J. G.

2007-12-01

Ambient measurements of trace metals identified as hazardous air pollutants (HAPs, air toxics) collected in the United States from 1990 to 2006 were analyzed for long-term trends. Trace metals analyzed include lead, manganese, arsenic, chromium, nickel, cadmium, and selenium. Visual and statistical analyses were used to identify and quantify temporal variations in air toxics at national and regional levels. Trend periods were required to be at least five years. Lead particles decreased in concentration at most monitoring sites, but trends in other metals were not consistent over time or spatially. In addition, routine ambient monitoring methods had method detection limits (MDLs) too high to adequately measure concentrations for trends analysis. Differences between measurement methods at urban and rural sites also confound trends analyses. Improvements in MDLs, and a better understanding of comparability between networks, are needed to better quantify trends in trace metal concentrations in the future.

Massive sulfide deposition and trace element remobilization in the Middle Valley sediment-hosted hydrothermal system, northern Juan de Fuca Rdge

USGS Publications Warehouse

Houghton, J.L.; Shanks, Wayne C.; Seyfried, W.E.

2004-01-01

The Bent Hill massive sulfide deposit and ODP Mound deposit in Middle Valley at the northernmost end of the Juan de Fuca Ridge are two of the largest modern seafloor hydrothermal deposits yet explored. Trace metal concentrations of sulfide minerals, determined by laser-ablation ICP-MS, were used in conjunction with mineral paragenetic studies and thermodynamic calculations to deduce the history of fluid-mineral reactions during sulfide deposition. Detailed analyses of the distribution of metals in sulfides indicate significant shifts in the physical and chemical conditions responsible for the trace element variability observed in these sulfide deposits. Trace elements (Mn, Co, Ni, As, Se, Ag, Cd, Sb, Pb, and Bi) analyzed in a representative suite of 10 thin sections from these deposits suggest differences in conditions and processes of hydrothermal alteration resulting in mass transfer of metals from the center of the deposits to the margins. Enrichments of some trace metals (Pb, Sb, Cd, Ag) in sphalerite at the margins of the deposits are best explained by dissolution/reprecipitation processes consistent with secondary remineralization. Results of reaction-path models clarify mechanisms of mass transfer during remineralization of sulfide deposits due to mixing of hydrothermal fluids with seawater. Model results are consistent with patterns of observed mineral paragenesis and help to identify conditions (pH, redox, temperature) that may be responsible for variations in trace metal concentrations in primary and secondary minerals. Differences in trace metal distributions throughout a single deposit and between nearby deposits at Middle Valley can be linked to the history of metal mobilization within this active hydrothermal system that may have broad implications for sulfide ore formation in other sedimented and unsedimented ridge systems. ?? 2004 Elsevier Ltd.

[Determination of trace heavy metal elements in cortex Phellodendron chinense by ICP-MS after microwave-assisted digestion].

PubMed

Kou, Xing-Ming; Xu, Min; Gu, Yong-Zuo

2007-06-01

An inductively coupled plasma mass spectrometry (ICP-MS) for determination of the contents of 8 trace heavy metal elements in cortex Phellodendron chinense after microwave-assisted digestion of the sample has been developed. The accuracy of the method was evaluated by the analysis of corresponding trace heavy metal elements in standard reference materials (GBW 07604 and GBW 07605). By applying the proposed method, the contents of 8 trace heavy metal elements in cortex Phellodendron chinense cultivated in different areas (in Bazhong, Yibin and Yingjing, respectively) of Sichuan and different growth period (6, 8 and 10 years of samples from Yingjing) were determined. The relative standard deviation (RSD) is in the range of 3.2%-17.8% and the recoveries of standard addition are in the range of 70%-120%. The results of the study indicate that the proposed method has the advantages of simplicity, speediness and sensitivity. It is suitable for the determination of the contents of 8 trace heavy metal elements in cortex Phellodendron chinense. The results also show that the concentrations of 4 harmful trace heavy metal elements As, Cd, Hg and Pb in cortex Phellodendron chinense are all lower than the limits of Chinese Pharmacopoeia and Green Trade Standard for Importing and Exporting Medicinal Plant and Preparation. Therefore, the cortex Phellodendron chinense is fit for use as medicine and export.

Lead sequestration and species redistribution during soil organic matter decomposition

USGS Publications Warehouse

Schroth, A.W.; Bostick, B.C.; Kaste, J.M.; Friedland, A.J.

2008-01-01

The turnover of soil organic matter (SOM) maintains a dynamic chemical environment in the forest floor that can impact metal speciation on relatively short timescales. Here we measure the speciation of Pb in controlled and natural organic (O) soil horizons to quantify changes in metal partitioning during SOM decomposition in different forest litters. We provide a link between the sequestration of pollutant Pb in O-horizons, estimated by forest floor Pb inventories, and speciation using synchrotron-based X-ray fluorescence and X-ray absorption spectroscopy. When Pb was introduced to fresh forest Oi samples, it adsorbed primarily to SOM surfaces, but as decomposition progressed over two years in controlled experiments, up to 60% of the Pb was redistributed to pedogenic birnessite and ferrihydrite surfaces. In addition, a significant fraction of pollutant Pb in natural soil profiles was associated with similar mineral phases (???20-35%) and SOM (???65-80%). Conifer forests have at least 2-fold higher Pb burdens in the forest floor relative to deciduous forests due to more efficient atmospheric scavenging and slower organic matter turnover. We demonstrate that pedogenic minerals play an important role in surface soil Pb sequestration, particularly in deciduous forests, and should be considered in any assessment of pollutant Pb mobility. ?? 2008 American Chemical Society.

Biogeochemical and hydrological controls on fate and distribution of trace metals in oiled Gulf salt marshes

NASA Astrophysics Data System (ADS)

Keevan, J.; Natter, M.; Lee, M.; Keimowitz, A.; Okeke, B.; Savrda, C.; Saunders, J.

2011-12-01

On April 20, 2010, the drilling rig Deepwater Horizon exploded in the Gulf of Mexico, resulting in the release of approximately 5 million barrels of crude oil into the environment. Oil and its associated trace metals have been demonstrated to have a detrimental effect on coastal wetland ecosystems. Wetlands are particularly susceptible to oil contamination because they are composed largely of fine-grained sediments, which have a high capacity to adsorb organic matter and metals. The biogeochemical cycling of trace metals can be strongly influenced by microbial activity, specifically those of sulfate- and iron-reducing bacteria. Microbial activity may be enhanced by an increase in amounts of organic matter such as oil. This research incorporates an assessment of levels of trace metals and associated biogeochemical changes from ten coastal marshes in Alabama, Mississippi, and Louisiana. These sampling sites range in their pollution levels from pristine to highly contaminated. A total digestion analysis of wetland sediments shows higher concentrations of certain trace metals (e.g., Ni, Cu, Pb, Zn, Sr, Co, V, Ba, Hg, As) in heavily-oiled areas compared to less-affected and pristine sites. Due to chemical complexation among organic compounds and metals, crude oils often contain elevated levels (up to hundreds of mg/kg) of trace metals At the heavily-oiled Louisiana sites (e.g., Bay Jimmy, Bayou Dulac, Bay Batiste), elevated levels of metals and total organic carbon have been found in sediments down to depths of 30 cm. Clearly the contamination is not limited to shallow sediments and oil, along with various associated metals, may be invading into deeper (pre-industrial) portions of the marsh sediments. Pore-waters extracted from contaminated sediments are characterized by very high levels of reduced sulfur (up to 80 mg/kg), in contrast to fairly low ferrous iron concentrations (<0.02 mg/kg). The influx of oil into the wetlands might provide the initial substrate and carbon source for stimulating sulfate-reducing bacteria. The high sulfur levels, coupled with the low levels of iron, indicate that iron-reducing bacteria are outcompeted by sulfate reducers in oiled salt marshes. Moreover, pore-water pH values show a general increasing trend (ranging from 6.6 to 8.0) with depth, possibly reflecting the combined effects of bacterial sulfate reduction and saltwater intrusion at depth. Despite high levels of trace metals in bulk sediments, concentrations of trace metals dissolved in pore-waters are generally low. It is very likely that high organic matter content and bacterially-mediated sulfate reduction promote metal retention through the formation of sulfide solids. Framboidal pyrites, as well as other sulfides, have been identified, and are currently undergoing XRD, SEM, and EDAX analyses. Continued research is needed to monitor possible re-mobilization of trace metals in changing redox and biogeochemical conditions.

Method for chromium analysis and speciation

DOEpatents

Aiken, Abigail M.; Peyton, Brent M.; Apel, William A.; Petersen, James N.

2004-11-02

A method of detecting a metal in a sample comprising a plurality of metal is disclosed. The method comprises providing the sample comprising a metal to be detected. The sample is added to a reagent solution comprising an enzyme and a substrate, where the enzyme is inhibited by the metal to be detected. An array of chelating agents is used to eliminate the inhibitory effects of additional metals in the sample. An enzymatic activity in the sample is determined and compared to an enzymatic activity in a control solution to detect the metal to be detected. A method of determining a concentration of the metal in the sample is also disclosed. A method of detecting a valence state of a metal is also disclosed.

Mercury speciation with fluorescent gold nanocluster as a probe.

PubMed

Yang, Jian-Yu; Yang, Ting; Wang, Xiao-Yan; Chen, Ming-Li; Yu, Yong-Liang; Wang, Jian-Hua

2018-05-11

Fluorescent nanoparticles are widely used for sensing biologically significant species. However, it is rarely reported for the discrimination or speciation of metal species. In this work, we report for the first time the speciation of mercury (Hg 2+ ) and methylmercury (CH 3 Hg + ) by taking advantage of the fluorescence feature of folic acid-capped gold nanoclusters (FA-AuNCs). FA-Au NCs exhibit an average size of 2.08±0.15 nm and a maximum emission at λ ex /λ em = 280/440 nm with a quantum yield of 27.3%. It is interesting that Hg 2+ causes a significant quench on the fluorescence of FA-Au NCs, whereas CH 3 Hg + leads to a remarkable fluorescence enhancement. Based on this discriminative fluorescent response between Hg 2+ and CH 3 Hg + , a novel nanosensor for the speciation of CH 3 Hg + and Hg 2+ was developed, providing limits of detection (LOD) of 28 nM for Hg 2+ and 25 nM for CH 3 Hg + within 100-1000 nM. This sensing system is highly selective to mercury. Its practical applications were further demonstrated by the analysis of CH 3 Hg + and the speciation of mercury (CH 3 Hg + and Hg 2+ ) in environmental water and fish samples.

Determination of trace elements in dairy milk collected from the environment of coal-fired power plant.

PubMed

Ramamurthy, N; Thillaivelavan, K

2005-01-01

In the present study the environmental effects on herbivores mammals in and around Coal-fired power plant were studied by collecting the various milk samples of Cow and Buffalo in clean polyethylene bottles. Milk samples collected at five different locations along the banks of the Paravanaru river in and around Neyveli area. These samples were prepared for trace metal determination. The concentration of trace metals (Cu, Zn, Ni, Cd, Cr, Mn, Co and Hg) were determined by Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and Cold Vapour Atomic Absorption Spectrometry (CVAAS). It is observed that the samples contain greater amounts of trace metals than that in the unexposed areas. Obviously the milk samples are contaminated with these metals due to fly ash released in such environment.

Influence of size-fractioning techniques on concentrations of selected trace metals in bottom materials from two streams in northeastern Ohio

USGS Publications Warehouse

Koltun, G.F.; Helsel, Dennis R.

1986-01-01

Identical stream-bottom material samples, when fractioned to the same size by different techniques, may contain significantly different trace-metal concentrations. Precision of techniques also may differ, which could affect the ability to discriminate between size-fractioned bottom-material samples having different metal concentrations. Bottom-material samples fractioned to less than 0.020 millimeters by means of three common techniques (air elutriation, sieving, and settling) were analyzed for six trace metals to determine whether the technique used to obtain the desired particle-size fraction affects the ability to discriminate between bottom materials having different trace-metal concentrations. In addition, this study attempts to assess whether median trace-metal concentrations in size-fractioned bottom materials of identical origin differ depending on the size-fractioning technique used. Finally, this study evaluates the efficiency of the three size-fractioning techniques in terms of time, expense, and effort involved. Bottom-material samples were collected at two sites in northeastern Ohio: One is located in an undeveloped forested basin, and the other is located in a basin having a mixture of industrial and surface-mining land uses. The sites were selected for their close physical proximity, similar contributing drainage areas, and the likelihood that trace-metal concentrations in the bottom materials would be significantly different. Statistically significant differences in the concentrations of trace metals were detected between bottom-material samples collected at the two sites when the samples had been size-fractioned by means of air elutriation or sieving. Statistical analyses of samples that had been size fractioned by settling in native water were not measurably different in any of the six trace metals analyzed. Results of multiple comparison tests suggest that differences related to size-fractioning technique were evident in median copper, lead, and iron concentrations. Technique-related differences in copper concentrations most likely resulted from contamination of air-elutriated samples by a feed tip on the elutriator apparatus. No technique-related differences were observed in chromium, manganese, or zinc concentrations. Although air elutriation was the most expensive sizefractioning technique investigated, samples fractioned by this technique appeared to provide a superior level of discrimination between metal concentrations present in the bottom materials of the two sites. Sieving was an adequate lower-cost but more laborintensive alternative.

Performance of Raphidocelis subcapitata exposed to heavy metal mixtures.

PubMed

Expósito, Nora; Kumar, Vikas; Sierra, Jordi; Schuhmacher, Marta; Giménez Papiol, Gemma

2017-12-01

Microalgae growth inhibition assays are candidates for referent ecotoxicological assays, and are a fundamental part in the strategy to reduce the use of fish and other animal models in aquatic toxicology. In the present work, the performance of Raphidocelis subcapitata exposed to heavy metals following standardized growth inhibition assays has been assessed in three different scenarios: 1) dilutions of single heavy metals, 2) artificial mixture of heavy metals at similar levels than those found in natural rivers and, 3) natural samples containing known mixtures of contaminants (heavy metals). Chemical speciation of heavy metals has been estimated with Eh-pH diagram and Visual MINTEQ software; heavy metal and free heavy metal ion concentrations were used as input data, together with microalgae growth inhibition, for Dr. Fit software. The final goal was to assess the suitability of the ecotoxicological test based on the growth inhibition of microalgae cultures, and the mathematic models based on these results, for regulatory and decision-making purposes. The toxicity of a given heavy metal is not only determined by its chemical speciation; other chemical and biological interaction play an important role in the final toxicity. Raphidocelis subcapitata 48h-h-EC50 for tested heavy metals (especially Cu and Zn) were in agreement with previous studies, when ion metal bioavailability was assumed to be 100%. Nevertheless, the calculated growth inhibition was not in agreement with the obtained inhibition when exposed to the artificial mixture of heavy metals or the natural sample. Interactions between heavy metal ions and the compounds of the culture media and/or the natural sample determine heavy metal bioavailability, and eventually their toxicity. More research is needed for facing the challenge posed by pollutant mixtures as they are present in natural environments, and make microalgae-based assays suitable for pollution management and regulatory purposes. Copyright © 2017 Elsevier B.V. All rights reserved.

Insights into the chemical partitioning of trace metals in roadside and off-road agricultural soils along two major highways in Attica's region, Greece.

PubMed

Botsou, Fotini; Sungur, Ali; Kelepertzis, Efstratios; Soylak, Mustafa

2016-10-01

We report in this study the magnetic properties and partitioning patterns of selected trace metals (Pb, Zn, Cu, Cd, Ni) in roadside and off-road (>200m distance from the road edge) agricultural soils collected along two major highways in Greece. Sequential extractions revealed that the examined trace metals for the entire data set were predominantly found in the residual fraction, averaging 37% for Cd up to 80% for Cu. Due to the strong influence of lithogenic factors, trace metal pseudototal contents of the roadside soils did not differ significantly to those of the off-road soils. Magnetic susceptibility and frequency dependent magnetic susceptibility determinations showed a magnetic enhancement of soils; however, it was primarily related to geogenic factors and not to traffic-derived magnetic particles. These results highlight that in areas characterized by strong geogenic backgrounds, neither pseudototal trace metal contents nor magnetic properties determinations effectively capture traffic-related contamination of topsoils. The vehicular emission signal was traced by the increased acid-soluble and reducible trace metal contents of the roadside soils compared to their off-road counterparts. In the case of Cu and Zn, changes in the partitioning patterns were also observed between the roadside and off-road soils. Environmental risks associated with agricultural lands extending at the margins of the studied highways may arise from the elevated Ni contents (both pseudototal and potentially mobile), and future studies should investigate Ni levels in the edible parts of plants grown on these agricultural soils. Copyright © 2016 Elsevier Inc. All rights reserved.

Laser Direct Metal Deposition of 2024 Al Alloy: Trace Geometry Prediction via Machine Learning.

PubMed

Caiazzo, Fabrizia; Caggiano, Alessandra

2018-03-19

Laser direct metal deposition is an advanced additive manufacturing technology suitably applicable in maintenance, repair, and overhaul of high-cost products, allowing for minimal distortion of the workpiece, reduced heat affected zones, and superior surface quality. Special interest is growing for the repair and coating of 2024 aluminum alloy parts, extensively utilized for a wide range of applications in the automotive, military, and aerospace sectors due to its excellent plasticity, corrosion resistance, electric conductivity, and strength-to-weight ratio. A critical issue in the laser direct metal deposition process is related to the geometrical parameters of the cross-section of the deposited metal trace that should be controlled to meet the part specifications. In this research, a machine learning approach based on artificial neural networks is developed to find the correlation between the laser metal deposition process parameters and the output geometrical parameters of the deposited metal trace produced by laser direct metal deposition on 5-mm-thick 2024 aluminum alloy plates. The results show that the neural network-based machine learning paradigm is able to accurately estimate the appropriate process parameters required to obtain a specified geometry for the deposited metal trace.

Laser Direct Metal Deposition of 2024 Al Alloy: Trace Geometry Prediction via Machine Learning

PubMed Central

2018-01-01

Laser direct metal deposition is an advanced additive manufacturing technology suitably applicable in maintenance, repair, and overhaul of high-cost products, allowing for minimal distortion of the workpiece, reduced heat affected zones, and superior surface quality. Special interest is growing for the repair and coating of 2024 aluminum alloy parts, extensively utilized for a wide range of applications in the automotive, military, and aerospace sectors due to its excellent plasticity, corrosion resistance, electric conductivity, and strength-to-weight ratio. A critical issue in the laser direct metal deposition process is related to the geometrical parameters of the cross-section of the deposited metal trace that should be controlled to meet the part specifications. In this research, a machine learning approach based on artificial neural networks is developed to find the correlation between the laser metal deposition process parameters and the output geometrical parameters of the deposited metal trace produced by laser direct metal deposition on 5-mm-thick 2024 aluminum alloy plates. The results show that the neural network-based machine learning paradigm is able to accurately estimate the appropriate process parameters required to obtain a specified geometry for the deposited metal trace. PMID:29562682

Zn(II) and Hg(II) binding to a designed peptide that accommodates different coordination geometries.

PubMed

Szunyogh, Dániel; Gyurcsik, Béla; Larsen, Flemming H; Stachura, Monika; Thulstrup, Peter W; Hemmingsen, Lars; Jancsó, Attila

2015-07-28

Designed metal ion binding peptides offer a variety of applications in both basic science as model systems of more complex metalloproteins, and in biotechnology, e.g. in bioremediation of toxic metal ions, biomining or as artificial enzymes. In this work a peptide (HS: Ac-SCHGDQGSDCSI-NH2) has been specifically designed for binding of both Zn(II) and Hg(II), i.e. metal ions with different preferences in terms of coordination number, coordination geometry, and to some extent ligand composition. It is demonstrated that HS accommodates both metal ions, and the first coordination sphere, metal ion exchange between peptides, and speciation are characterized as a function of pH using UV-absorption-, synchrotron radiation CD-, (1)H-NMR-, and PAC-spectroscopy as well as potentiometry. Hg(II) binds to the peptide with very high affinity in a {HgS2} coordination geometry, bringing together the two cysteinates close to each end of the peptide in a loop structure. Despite the high affinity, Hg(II) is kinetically labile, exchanging between peptides on the subsecond timescale, as indicated by line broadening in (1)H-NMR. The Zn(II)-HS system displays more complex speciation, involving monomeric species with coordinating cysteinates, histidine, and a solvent water molecule, as well as HS-Zn(II)-HS complexes. In summary, the HS peptide displays conformational flexibility, contains many typical metal ion binding groups, and is able to accommodate metal ions with different structural and ligand preferences with high affinity. As such, the HS peptide may be a scaffold offering binding of a variety of metal ions, and potentially serve for metal ion sequestration in biotechnological applications.

Speciation of heavy metals in different grain sizes of Jiaozhou Bay sediments: Bioavailability, ecological risk assessment and source analysis on a centennial timescale.

PubMed

Kang, Xuming; Song, Jinming; Yuan, Huamao; Duan, Liqin; Li, Xuegang; Li, Ning; Liang, Xianmeng; Qu, Baoxiao

2017-09-01

Heavy metal contamination is an essential indicator of environmental health. In this work, one sediment core was used for the analysis of the speciation of heavy metals (Cr, Mn, Ni, Cu, Zn, As, Cd, and Pb) in Jiaozhou Bay sediments with different grain sizes. The bioavailability, sources and ecological risk of heavy metals were also assessed on a centennial timescale. Heavy metals were enriched in grain sizes of < 63µm and were predominantly present in residual phases. Moreover, the mobility sequence based on the sum of the first three phases (for grain sizes of < 63µm) was Mn > Pb > Cd > Zn > Cu >Ni > Cr > As. Enrichment factors (EF) indicated that heavy metals in Jiaozhou Bay presented from no enrichment to minor enrichment. The potential ecological risk index (RI) indicated that Jiaozhou Bay had been suffering from a low ecological risk and presented an increasing trend since 1940s owing to the increase of anthropogenic activities. The source analysis indicated that natural sources were primary sources of heavy metals in Jiaozhou Bay and anthropogenic sources of heavy metals presented an increasing trend since 1940s. The principal component analysis (PCA) indicated that Cr, Mn, Ni, Cu and Pb were primarily derived from natural sources and that Zn and Cd were influenced by shipbuilding industry. Mn, Cu, Zn and Pb may originate from both natural and anthropogenic sources. As may be influenced by agricultural activities. Moreover, heavy metals in sediments of Jiaozhou Bay were clearly influenced by atmospheric deposition and river input. Copyright © 2017. Published by Elsevier Inc.

A field survey of metal binding to metallothionein and other cytosolic ligands in liver of eels using an on-line isotope dilution method in combination with size exclusion (SE) high pressure liquid chromatography (HPLC) coupled to Inductively Coupled Plasma time-of-flight Mass Spectrometry (ICP-TOFMS).

PubMed

Van Campenhout, Karen; Goenaga Infante, Heidi; Goemans, Geert; Belpaire, Claude; Adams, Freddy; Blust, Ronny; Bervoets, Lieven

2008-05-15

The effect of metal exposure on the accumulation and cytosolic speciation of metals in livers of wild populations of European eel with special emphasis on metallothioneins (MT) was studied. Four sampling sites in Flanders showing different degrees of heavy metal contamination were selected for this purpose. An on-line isotope dilution method in combination with size exclusion (SE) high pressure liquid chromatography (HPLC) coupled to Inductively Coupled Plasma time-of-flight Mass Spectrometry (ICP-TOFMS) was used to study the cytosolic speciation of the metals. The distribution of the metals Cd, Cu, Ni, Pb and Zn among cytosolic fractions displayed strong differences. The cytosolic concentration of Cd, Ni and Pb increased proportionally with the total liver levels. However, the cytosolic concentrations of Cu and Zn only increased above a certain liver tissue threshold level. Cd, Cu and Zn, but not Pb and Ni, were largely associated with the MT pool in correspondence with the environmental exposure and liver tissue concentrations. Most of the Pb and Ni and a considerable fraction of Cu and Zn, but not Cd, were associated to High Molecular Weight (HMW) fractions. The relative importance of the Cu and Zn in the HMW fraction decreased with increasing contamination levels while the MT pool became progressively more important. The close relationship between the cytosolic metal load and the total MT levels or the metals bound on the MT pool indicates that the metals, rather than other stress factors, are the major factor determining MT induction.

Heavy metal partitioning of suspended particulate matter-water and sediment-water in the Yangtze Estuary.

PubMed

Feng, Chenghong; Guo, Xiaoyu; Yin, Su; Tian, Chenhao; Li, Yangyang; Shen, Zhenyao

2017-10-01

The partitioning of ten heavy metals (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Sb, and Zn) between the water, suspended particulate matter (SPM), and sediments in seven channel sections during three hydrologic seasons in the Yangtze Estuary was comprehensively investigated. Special attention was paid to the role of tides, influential factors (concentrations of SPM and dissolved organic carbon, and particle size), and heavy metal speciation. The SPM-water and sediment-water partition coefficients (K p ) of the heavy metals exhibited similar changes along the channel sections, though the former were larger throughout the estuary. Because of the higher salinity, the K p values of most of the metals were higher in the north branch than in the south branch. The K p values of Cd, Co, and As generally decreased from the wet season to the dry season. Both the diagonal line method and paired samples t-test showed that no specific phase transfer of heavy metals existed during the flood and ebb tides, but the sediment-water K p was more concentrated for the diagonal line method, owing to the relatively smaller tidal influences on the sediment. The partition coefficients (especially the K p for SPM-water) had negative correlations with the dissolved organic carbon (DOC) but positive correlations were noted with the particle size for most of the heavy metals in sediment. Two types of significant correlations were observed between K p and metal speciation (i.e., exchangeable, carbonate, reducible, organic, and residual fractions), which can be used to identify the dominant phase-partition mechanisms (e.g., adsorption or desorption) of heavy metals. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biosorptive recovery of platinum from platinum group metal refining wastewaters by immobilised Saccharomyces cerevisiae.

PubMed

Mack, C L; Wilhelmi, B; Duncan, J R; Burgess, J E

2011-01-01

The process of platinum group metal (PGM) refining can be up to 99.99% efficient at best, and although it may seem small, the amount of valuable metal lost to waste streams is appreciable enough to warrant recovery. The method currently used to remove entrained metal ions from refinery wastewaters, chemical precipitation, is not effective for selective recovery of PGMs. The yeast Saccharomyces cerevisiae has been found capable of sorbing numerous precious and base metals, and is a cheap and abundant source of biomass. In this investigation, S. cerevisiae was immobilised using polyethyleneimine and glutaraldehyde to produce a suitable sorbent, capable of high platinum uptake (150-170 mg/g) at low pH (<2). The sorption mechanism was found to be a chemical reaction, which made effective desorption impossible. When applied to PGM refinery wastewater, two key wastewater characteristics limited the success of the sorption process; high inorganic ion content and complex speciation of the platinum ions. The results proved the concept principle of platinum recovery by immobilised yeast biosorption and indicated that a more detailed understanding of the platinum speciation within the wastewater is required before biosorption can be applied. Overall, the sorption of platinum by the S. cerevisiae sorbent was demonstrated to be highly effective in principle, but the complexity of the wastewater requires that pretreatment steps be taken before the successful application of this process to industrial wastewater.

Trace elements geochemistry of fractured basement aquifer in southern Malawi: A case of Blantyre rural

NASA Astrophysics Data System (ADS)

Mapoma, Harold Wilson Tumwitike; Xie, Xianjun; Nyirenda, Mathews Tananga; Zhang, Liping; Kaonga, Chikumbusko Chiziwa; Mbewe, Rex

2017-07-01

In this study, twenty one (21) trace elements in the basement complex groundwater of Blantyre district, Malawi were analyzed. The majority of the analyzed trace elements in the water were within the standards set by World Health Organization (WHO) and Malawi Standards Board (MSB). But, iron (Fe) (BH16 and 21), manganese (Mn) (BH01) and selenium (Se) (BH02, 13, 18, 19 and 20) were higher than the WHO and MSB standards. Factor analysis (FA) revealed up to five significant factors which accounted for 87.4% of the variance. Factor 1, 2 and 3 suggest evaporite dissolution and silicate weathering processes while the fourth factor may explain carbonate dissolution and pH influence on trace element geochemistry of the studied groundwater samples. According to PHREEQC computed saturation indices, dissolution, precipitation and rock-water-interaction control the levels of trace elements in this aquifer. Elevated concentrations of Fe, Mn and Se in certain boreholes are due to the geology of the aquifer and probable redox status of groundwater. From PHREEQC speciation results, variations in trace element species were observed. Based on this study, boreholes need constant monitoring and assessment for human consumption to avoid health related issues.

WATER, SALT AND CLIMATE CHANGE

EPA Science Inventory

The application of synchrotron based research for understanding the fate of contaminants in water, soil, and atmosphere is proving to be beneficial for scientists and regulators. Drawing the connection of a contaminated site to knowledge of metal speciation provides direct eviden...

Changes in heavy metal mobility and availability from contaminated wetland soil remediated with combined biochar-compost.

PubMed

Liang, Jie; Yang, Zhaoxue; Tang, Lin; Zeng, Guangming; Yu, Man; Li, Xiaodong; Wu, Haipeng; Qian, Yingying; Li, Xuemei; Luo, Yuan

2017-08-01

The combination of biochar and compost has been proven to be effective in heavy metals contaminated wetland soil restoration. However, the influence of different proportions between biochar and compost on immobilization of heavy metals in soil has been less studied up to date. Therefore, we investigated the effect of different ratios of biochar-compost mixtures on availability and speciation distribution of heavy metals (Cd, Zn and Cu) in wetland soil. The results showed that applying all amendment combinations into wetland soil increased gradually the total organic carbon (TOC) and water-extract organic carbon (WEOC) as the compost percentage rose in biochar-composts. The higher pH was obtained in a certain biochar addition (20% and 40%) in combinations due to efficient interaction of biochar with compost. All amendments could significantly decrease availability of Cd and Zn mainly from pH change, but increase available Cu concentration as the result of increased water-extract organic carbon and high total Cu content in compost. Moreover, amendments can decrease easily exchangeable fraction and increase reducible of Cd and Zn greatly with increase of compost content in combinations, while amendments containing compost promote transformation of Cu from Fe/Mn oxide and residual fractions to organic bindings. These results demonstrate that different ratios of biochar and compost have a significant effect on availability and speciation of heavy metals in multi-metal-contaminated wetland soil. Copyright © 2017 Elsevier Ltd. All rights reserved.

Parallel Elemental and Molecular Mass Spectrometry (PEMMS) for Speciation of Metals in Complex Matrices

NASA Astrophysics Data System (ADS)

Derry, L. A.; Sacks, G. L.; Brenna, J. T.

2006-12-01

The mobility, bioavailability, and toxicity of many metals are strongly influenced by their molecular form, or speciation. Many metals (M) in the environment are complexed with organic ligands (L); in some cases such complexed forms comprise virtually all of the dissolved metal. When available, stability constants can be used to model speciation, but only when the identities of species can be known or assumed. In other cases, coupling a separation tool such as HPLC to a metal detection system like ICP-MS can provide information on speciation. But because ICP-MS destroys molecular information the complexing L must be identified by retention time matching of standards. The assumptions inherent in these approaches preclude investigation of unknown compounds. Electrochemical methods can determine conditional stability constants for unknown L but do not provide information on their molecular structure or composition. Molecular MS allows characterization of molecular mass and structure and is a powerful tool for identifying unknown organic compounds. However, sensitivity for M and precision for isotope ratios are often low. We combined HPLC separation with simultaneous parallel detection of metals (M) and ligands (L) by ICP-MS and API-QTOF-MS-MS. The basis of our approach is that the shape of a chromatographic peak is essentially set by interactions with the LC column. The signal of a metal M determined by the ICP-MS in chromatographic mode is fit using an exponentially modified Gaussian function. Peak parameters including retention time, peak width and skew are determined for the M peak. The parallel QTOF signal in full scan mode may show hundreds of peaks in the same time window. The acquired peak library is searched for L peaks that match the parameters determined for the M peak on the ICP-MS. We have found that our system can correctly identify M-L pairs and L in complex samples and generates few false positives. Unknown L can be further interrogated by using the MS-MS product ion scan mode of the QTOF, in which candidate peaks are fragmented in a collision cell after MS1 and the fragments analyzed by MS2. The combination of precise mass determinations, recognition of isotopomers, and product ion scans can often identify unknown M-L in complex natural mixtures without prior knowledge of the sample composition. Data from seleno-compounds illustrate the PEMMS concept. An artificially noisy sample was generated by spiking 30 ppb Se-methionine (SeMet) and 5 ppb Se-methylselenocysteine (SeMSC) with unselenized yeast extract and run by PEMMS. The PEMMS software was able to detect four molecular MS peaks associated with SeMet and two for SeMSC, while filtering out more than 40 co-eluting spectral peaks associated with chemical noise in each sample. Additional data from Cu-thiols produced by marine plankton and soil chelates of Al demonstrate the utility of the PEMMS approach in the study of natural environmental systems.

Interactions Among Chemical Speciation, Algal Accumulation, and Biogeochemical Cycling of Toxic Metals in a Major US Naval Harbor (Elizabeth River, VA)

DTIC Science & Technology

2001-09-30

Elizabeth River/Hampton Roads system and algal species grown in metal ion buff er systems: Emiliania huxleyi , Thalassiosira pseudonana, and... huxleyi -0 o ... • Elizabeth, May E ~ · + Elizabeth, July :::: 100. 6~ ~· 0 0 T. pseuclonana §_ 0 • tJ 0 8 ~ 0 0 0 <>I. galbana - 𔃺~0 0 (.) 10. s

Potentiometric titration of metal ions in ethanol.

PubMed

Gibson, Graham T T; Mohamed, Mark F; Neverov, Alexei A; Brown, R S

2006-09-18

The potentiometric titrations of Zn2+, Cu2+ and 12 Ln3+ metal ions were obtained in ethanol to determine the titration constants (defined as the at which the [-OEt]/[Mx+]t ratios are 0.5, 1.5, and 2.5) and in two cases (La3+ and Zn2+) a complete speciation diagram. Several simple monobasic acids and aminium ions were also titrated to test the validity of experimental titration measurements and to establish new constants in this medium that will be useful for the preparation of buffers and standard solutions. The dependence of the titration constants on the concentration and type of metal ion and specific counterion effects is discussed. In selected cases, the titration profiles were analyzed using a commercially available fitting program to obtain information about the species present in solution, including La3+ for which a dimer model is proposed. The fitting provides the microscopic values for deprotonation of one to four metal-bound ethanol molecules. Kinetics for the La3+-catalyzed ethanolysis of paraoxon as a function of are presented and analyzed in terms of La3+ speciation as determined by the analysis of potentiometric titration curves. The stability constants for the formation of Zn2+ and Cu2+ complexes with 1,5,9-triazacyclododecane as determined by potentiometric titration are presented.

Modeling of phytoextraction efficiency of microbially stimulated Salix dasyclados L. in the soils with different speciation of heavy metals.

PubMed

Złoch, Michał; Kowalkowski, Tomasz; Tyburski, Jarosław; Hrynkiewicz, Katarzyna

2017-12-02

Bioaugmentation of soils with selected microorganisms during phytoextraction can be the key solution for successful bioremediation and should be accurately calculated for different physicochemical soil properties and heavy metal availability to guarantee the universality of this method. Equally important is the development of an accurate prediction tool to manage phytoremediation process. The main objective of this study was to evaluate the role of three metallotolerant siderophore-producing Streptomyces sp. B1-B3 strains in the phytoremediation of heavy metals with the use of S. dasyclados L. growing in four metalliferrous soils as well as modeling the efficiency of this process based on physicochemical and microbiological properties of the soils using artificial neural network (ANN) analysis. The bacterial inoculation of plants significantly stimulated plant biomass and reduced oxidative stress. Moreover, the bacteria affected the speciation of heavy metals and finally their mobility, thereby enhancing the uptake and bioaccumulation of Zn, Cd, and Pb in the biomass. The best capacity for phytoextraction was noted for strain B1, which had the highest siderophore secretion ability. Finally, ANN model permitted to predict efficiency of phytoextraction based on both the physicochemical properties of the soils and the activity of the soil microbiota with high precision.