Academic literature on the topic 'Trace element contents'

Olivine forsterite contents [Fo = 100 × Mg/(Mg + Fe) in mol%] and minor–trace element concentrations can aid our understanding of the Earth’s mantle. Traditionally, these data are obtained by electron probe microanalysis for Fo contents and minor elements, and then by laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS) for trace elements. In this study, we demonstrate that LA–ICP–MS, with a simplified 100% quantification approach, allows the calculation of Fo contents simultaneously with minor–trace elements. The approach proceeds as follows: (1) calculation of Fo contents from measured Fe/Mg ratios; (2) according to the olivine stoichiometric formula [(Mg, Fe)2SiO4] and known Fo contents, contents of Mg, Fe and Si can be computed, which are used as internal standards for minor–trace element quantification. The Fo content of the MongOLSh 11-2 olivine reference material is 89.55 ± 0.15 (2 s; N = 120), which agrees with the recommended values of 89.53 ± 0.05 (2 s). For minor–trace elements, the results matched well with the recommended values, apart from P and Zn data. This technique was applied to olivine phenocrysts in the Lijiang picrites from the Emeishan large igneous province. The olivine compositions suggest that the Lijiang picrites have a peridotitic mantle source.

Nymphs of the burrowing mayfly Hexagenia limbata were collected in the field, returned to the laboratory, and dissected to remove the gut contents. Concentrations of four trace elements (As, Cd, Cu, Zn) were determined both for the gut contents and for the body. Trace elements in gut contents represented up to 22% of whole animal trace element burdens. Studies of depuration of H. limbata nymphs held in water for up to 48 h indicate that individuals vary substantially in the rate at which they egest gut contents and that 48 h is not sufficient to ensure a complete emptying of the gut. A model developed to compensate for the presence of gut contents in the determination of body trace element burdens was applied to H. limbata. Comparisons of model estimates with actual body burdens (without gut contents) show that the model accurately predicts As and Cu concentrations, but overestimates concentrations of Cd and Zn by as much as 20%. We suggest that the biases in the model result from assuming that: (a) trace element concentrations in gut sediments are equivalent to those in sediments sampled from the animal's surroundings, and (b) there is no weight loss of gut contents during sample digestion (a two-thirds weight loss of gut contents was in fact observed). These biases may be minimized by, respectively: (a) measuring trace element burdens of gut contents and (b) compensating for weight loss of gut contents during digestion.

AbstractThe aim of this study was to determine Cu, Fe and Cr contents of three species of fresh mushrooms and canned mushrooms: white and brown champignon (Agaricus bisporus) and Pleurotus Ostreatus. Were analyzed various plant parts: stem, cap and cuticle of fresh mushrooms and only stem and cap for canned mushrooms. The levels of trace metals of mushroom samples collected from regions of Romania, Poland and Turkey were determined by UV/Visible spectrometry - standard addition method after digestion method. The contents of investigated trace metals in mushroom samples were found to be in the range of 0.01 - 2.26 mg/Kg for chromium, 2.02 - 430.67 mg/Kg for copper and 240.40 - 7952.89 mg/Kg for iron. The iron content was found to be higher than those of the other two minerals in all the samples. Mushrooms species in the highest levels of trace elements were found white champignon for Cu and Fe and brown champignon for Cr.

In this paper, the characteristics o f trace metal elements were studied in Elsholtzia harchowensis. The relation of trace elements between plant and soil was studied, and the copper tolerance and mechanism of the plant was discussed in details. The results showed that the trace element contents of the soil was higher, Cu content was highest in these elements, and it was as more 200 times as that of control sites. Cu in the plant was highest in these elements and Cd was lowest. The elements sequence in plant was: Cu> Mn> Zn> Pb> Cd. Element contents in different parts of the plant were: Cu, root> flower> leaf> stem; Cd, leaf> flower> root> stem; Mn, leaf> root > flower> stem; Zn, leaf> flower> stem> root; Pb, root> leaf> stem> flower. There is positive correlation in Cu between plant and soil. The tolerance capacity is higher in the plant.

There are hundreds of years old wild sweet chestnut trees grown among alder, hornbeam, and pine etc. trees in natural forest of Giresun/TURKEY. In this study, trace element contents of chestnuts collected from chestnut trees in these natural forests were investigated. For this purpose, A total of eight elements, manganese (Mn), iron (Fe), zinc (Zn), nickel (Ni), cobalt (Co), selenium (Se) and lead (Pb) were determined by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) in chestnut samples collected from ten chestnut trees. The content of trace elements was determined separately in fruit, bark and pellicle parts of chestnut. In chestnut fruit samples, highest concentration values in mg kg-1 of Mn, Fe, Zn, Ni, Cu, Se, Co and Pb are: 88.29, 72.96, 27.76 8.25, 7.81, 2.28, 0.056 and 0.043 respectively. Chestnut bark has been shown the highest values as Mn 176.01, Fe 96.55, Zn 26.97, Ni 4.33, Cu 8.91, Se 3.08, Co 0.089 and Pb 0.058 mg kg-1. The highest concentrations of trace elements in chestnut pellicle are found as Mn 176.26, Fe 92.98, Zn 60.06, Ni 5.79, Cu 11.4, Se 3.29, Co 0.135 and Pb 0.095 mg kg-1. These results suggest that natural chestnuts grown in the Giresun region are quite rich nutrients in terms of trace element contents.

Des xénolites de péridotite provenant de deux localités du sud du Massif Central Français (Allègre et Mont Coupet), émis avec des modes éruptifs différents, ont été étudiés pour définir l’évolution du manteau sous continental et pour étudier le comportement de Li et H lors des réactions fluides roches lors de leur remonté vers la surface. Un ensemble de 6 xénolites représentatifs a été sélectionné pour chaque localité. La description pétrologique et minéralogique de chaque échantillon a été associée à la mesure des compositions chimiques en éléments majeur (par microsonde électronique) et trace (par LA-ICP-MS) des principales phases minéralogiques (Olivine, Pyroxène, Amphibole). La teneur et la composition isotopique du Li ont été mesurées par microsonde ionique (SIMS), et les teneurs en eau par spectroscopie infrarouge à transformée de Fourrier (FTIR) et SIMS dans les pyroxènes et les olivines. Pour les xénolites d’Allègre, les anomalies négatives en HFSE et les rapports LREE/HREE élevés reflètent un métasomatisme lié à des liquides carbonatitiques, succédant à un processus de fusion partielle du manteau lithosphérique. Pour les échantillons du Mont Coupet, Les anomalies négatives en Ti et Nb des Cpx de tous les échantillons et les anomalies négatives de Zr et Hf pour deux échantillons plus fortement métasomatisés (MC38 et MC34) soulignent également un métasomatisme carbonatitique. Les amphiboles des échantillons MC36 et MC53, dont l'origine doit être associée à des fluides de subduction, sont à l’équilibre avec les Cpx coexistant, ce qui indique que le fluide qui a permis leur formation n’a pas enrichi les Cpx en LREE ou LILE. La composition isotopique de des xénolites d’Allègre montre qu’ils ont été affectés par un métasomatisme en au moins deux étapes par des fluides différents. Les teneurs très élevées en Li des Cpx (jusqu'à 50 ppm) et l’enrichissement même modéré des bordures des olivines sont attribués à un apport de Li par diffusion depuis le magma hôte. Par contre, les compositions isotopiques pauvres en 7Li préservées au coeur des Ol (δ7Li jusqu’à -25‰) suggèrent l’existence d’un autre évènement métasomatique ayant affecté les péridotites avant leur remonté vers la surface. En revanche, les minéraux des xénolites de Mont Coupet ont des concentrations en Li similaires à celles du manteau, avec une répartition à l’équilibre entre les minéraux. Cependant les valeurs de δ7Li négatives observées pour les Cpx et Opx de certains échantillons suggèrent une interaction avec un fluide en quantité limitée et une composition isotopique négative. La préservation du fractionnement isotopique du Li entre les pyroxènes et olivines indique que cette interaction a du avoir lieu peu de temps avant l'entrainement des xénolites vers la surface. Les fluides métasomatiques à l’origine des valeurs de δ7Li négatives observées à Allègre et à Mont Coupet sont liés à un environnement de subduction, probablement lié à l'orogenèse varisque dans le cadre régional du FMC. Les teneurs en eau mesurées dans les xénolites d’Allègre vont de 10,6 à 12,4 ppm, des valeurs beaucoup plus faible que celle du manteau source des MORB. Ceci s’explique par une perte d’eau associée au dégazage du magma lors du refroidissement du lac de lave. L’absence de variation cœur-bord montre une distribution de l’eau à l’équilibre entre les xénolites et la lave hôte. A l’inverse, les xénolites du Mont Coupet ont pu conservé leur teneur en eau acquise en profondeur, contrôlée par les processus de fusion partielle qui ont affecté les péridotites. Cependant, l'échantillon MC34, affecté par le métasomatisme carbonatitique, a la plus haute teneur en eau parmi ces xénolites. Inversement, les échantillons MC36 et MC53 qui contiennent des amphiboles, n’ont pas des teneurs en eau élevées, suggérant que l'agent métasomatique responsable de la formation des amphiboles n'a pas enrichi en eau les autres phases de la péridotite
Peridotite xenoliths sampled from two volcanoes erupting in different modes in two localities, Allègre and Mont Coupet, in the southern domain of the French Massif Central (FMC), have been investigated to constrain the evolution of the sub-continental lithospheric mantle beneath the FMC and the behaviors of Li and H during melt-rock reactions. To answer these questions, a set of 6 representative xenoliths was selected for each locality, and described for their mineralogy and petrography. In-situ measurements were then performed for major and trace elements in Ol, Cpx and Amp when existing, via EPMA and LA-ICP-MS respectively, for Li concentrations and isotopic compositions in pyroxenes and Ol (via SIMS), and water concentrations in minerals (via FTIR and SIMS). Negative HFSE anomalies and markedly high LREE/HREE ratios reflect a carbonatite-related metasomatism following an earlier partial melting process in the lithospheric mantle under Allègre. The Ti and Nb negative anomalies in Cpx from all the Mont Coupet samples and Zr-Hf negative anomalies in Cpx from two most strongly metasomatized samples MC38 and MC34 also point to a carbonatite-related mantle metasomatism. Amp in samples MC36 and MC53, whose origin should be associated with fluids from the subducting slab, have equilibrated most of the trace element composition with coexisting Cpx and the modal metasomatism responsible for the Amp genesis haven’t refertilized Cpx in LREE and LILE. Lithium isotope systematics indicates that Allègre xenoliths were overprinted by (at least) a two-stage metasomatism by melts of different origins. Exceptionally high Li concentrations in Cpx (up to 50 ppm by weight) and slightly increased Li contents at Ol rims are ascribed to a diffusive Li uptake from infiltrating melts derived from the host magma. On the other hand, extremely light Li isotopic compositions preserved in Ol cores (with δ7Li as low as -25‰) suggest another metasomatic event prior to xenolith entrainment by the host magma. In contrast, xenoliths from Mont Coupet have Li concentrations in constituent minerals similar to the normal mantle, and display nearly equilibrated inter-mineral Li partitioning and homogeneous intragranular Li distribution in every phase. The negative δ7Li values of Cpx and Opx in some samples were brought by the exchange with a small-volume melt with Li concentration similar to the normal mantle and light Li isotopic compositions. The preservation of inter-mineral large Li isotopic fractionation currently observed in these samples indicates that the percolation of the melt should occur shortly prior to the entrainment of Mont Coupet peridotite xenoliths by the host magmas. The metasomatic agents, accounting for negative δ7Li values in Ol cores in Allègre xenoliths and in Cpx and Opx in some Mont Coupet xenoliths, are related to a subduction environment. In the regional framework of the FMC, the subduction event most likely occurred during the Variscan orogeny. Water content in Allègre xenoliths ranges from 10.6 to 12.4 ppm in weight, much lower than the water content in the MORB source mantle. It implies that water were lost during the degassing of the host magma during slow cooling of the lava lake. No core-rim variations from profile analysis suggest that xenoliths have achieved water diffusive equilibrium with the host magmas. Peridotite xenoliths from Mont Coupet have retained their original water content from the mantle depths. Partial melting has controlled the water content in most samples from Mont Coupet. However, the subsequent carbonatite-related metasomatism has affected the sample MC34, which had the highest water content among the Mont Coupet xenoliths. And the aqueous agent responsible for presence of Amp in samples MC36 and MC53 has not lead to the considerable increase of water content

Soil quality guidelines are currently based on total trace metal loads. There is a need to define indices of bioavailability to allow reasonable predictions for plant metal uptake and toxicity in soils. Trace metal toxicities to plants often correlate best with free metal ion activities. The first objective was to develop a plant bioassay that is sensitive to trace metals at concentrations realistic for soils. The root elongation of lettuce Lactuca sativa 'Buttercrunch' was used as toxicological endpoint. This endpoint was sensitive and reproducible to environmentally relevant concentrations of Cd, Cu, Ni, Pb and Zn. The second objective was to test whether free metal ion activities are constant predictors of metal toxicities in synthetic solutions and in soil extracts that differ in their concentrations of cations and ligands. The root elongation assay was used to test this hypothesis. In synthetic solutions, the rhizotoxicity of Cd, Cu, Ni, Pb and Zn decreased with increasing Ca and H concentrations. This could not be explained with the effect of higher cationic concentrations on root growth or on solution speciation. It was concluded that Ca and H inhibited the rhizotoxicity of all metals tested. The rhizotoxicity of Cu and Cd was further examined in soil extracts. Both metals became less rhizotoxic at higher H and dissolved organic matter concentrations. The rhizotoxicity endpoints from the experiments in synthetic solution were used to develop parameters for a Biotic Ligand Model (BLM) for Cd, Cu, Ni, Pb and Zn. The BLM accounts for solution speciation and interprets cationic inhibition of rhizotoxicity as competition of metals with Ca and H for potential sites of rhizotoxicity. The BLM predicted metal rhizotoxicity better than the free metal ion activity in synthetic solutions and in soil extracts. Different models were tested against literature rhizotoxicity data for metals at different Ca and H concentrations. Predictions for metal rhizotoxicity given by BLM, Gouy-Chapman-Stern model and Freundlich equation model were compared with predictions based on free metal ion activities in solution. The BLM predicted rhizotoxicity most accurately. The BLM seems promising for predictions of metal toxicity and metal bioavailability in soils to support site-specific environmental risk assessments.

Trace elements added to the soil by human activities could contaminate it and occasionally cause a threat to environmental and human health. The toxicity and mobility of a trace element are affected by the element's solubility, which in turn is influenced by the soil properties. When mobile, trace elements can be leached out of the soil. If leaching occurs at a faster rate than atmospheric deposition, element concentrations in the soil will decrease by natural attenuation.
We analyzed soil properties in 40 soils and their soil solutions to obtain a set of equations with the most significant predictors of As, Cd, Co, Cu, Mo, Ni, Pb and Zn in solution. The total element concentration and the pH were the best predicting variables of the amount of element in solution for all trace elements analyzed, while organic carbon and Al or Mn oxides also influenced the solubility of some trace elements. Using the equations predicting elemental solubility, we wrote a model for natural attenuation in the computer program Stella that considers atmospheric deposition as the input for trace elements and leaching as the output. Simulations were carried out for the 40 soils during 1,000 years with steady deposition inputs.
At current atmospheric deposition rates and the neutral to alkaline pH of these soils, attenuation occurred in most soils for Mo. For As, Cd, Co, Cu and Ni it occurred only in soils with abundant total element concentrations or an acidic pH. Minor retention occurred with Pb and Zn. Only Cd and Cu were of concern in leaching waters. The developed model can serve as a decision making tool in the selection of natural attenuation as a remediation strategy.

The Fäboliden gold deposit is an ore body in northern Sweden’s Bothnian Basin and has been the subject of studies and test mining since the early 2000s when the Gold Line, an area of anomalously high-Au glacial till in Northern Sweden, became a center of economic interest. The deposit is a hypozonal orogenic gold deposit that displays many characteristic features of ore bodies of this type, including the presence of compound sulfide grains composed of a core of löllingite surrounded by a rim of arsenopyrite, and an abundance of pyrrhotite throughout the deposit and surrounding alteration zone. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used to first map the distribution of trace elements in several of the arsenpyrite-löllingite grains, then to perform spot analyses of pyrrhotite grains in samples from across the distal and proximal alteration zones of the deposit. The maps of the trace elements in the compound löllingite-arsenopyrite grains show that: As and Au are found in greater abundance in the löllingite than in the arsenopyrite; Cu, Fe, S, and Ti are found in greater abundance in the arsenopyrite than in the löllingite; and Ag, Au, Bi, La, Mn, Pb, Sr, Ti and Tl are found in zones of secondary enrichment along fractures within the grains. Uranium and V may also be enriched along fractures, although this isn’t clear on all of the maps. Gold is an element of particular interest, because its distribution throughout the sulfide phases can be used to constrain the mechanism and relative timing of mineralization within the deposit. The presence of invisible gold within the löllingite, but not within the arsenopyrite, shows that gold is not incorporated into arsenopyrite at high temperatures and will instead be concentrated in the löllingite core of the composite grain and at the margin between the two sulfide phases as the löllingite is altered to arsenopyrite. Previous research on the Fäboliden gold deposit, including geothermometric analysis of vein-hosted graphite within fluid inclusions and garnet-biotite geothermometry as well as structural evidence provided by regional deformation, indicate that mineralization occurred post-peak metamorphism. The textures seen are therefore not conclusive of mineralization occurring syn- or pre-peak metamorphism, as has previously been proposed based on research of orogenic gold deposits in Western Australia. The spot analysis of pyrrhotite samples from across the deposit shows a distinct decrease in Ni and Co content in the proximal alteration zone, suggesting uptake of these elements by other minerals such as the löllingite and arsenopyrite. Multiple analyses performed on single grains show local variation, but are insufficient to establish the presence or determine the character of growth zonation within pyrrhotite.

Chapter 1 of this thesis is a general review of published work o_ the origins and distribution of Cd, Cu, Fe, Mn and Zn in soils and their uptake and functions in plants. Chapter 2 is a synopsis of the geological history of the Fayoum of relevance to the origins of sediments at the study sties. Previous fractionation procedures, and a proposed modification to improve the determination of carbonate-bound elements are discussed in Chapter 3, while other analytical procedures are described in Chapter 4. Results of general soil analyses, of the fractionation analyses and useful correlation matrices, are tabulated together (for convenience in Chapter 5) and are discussed in detail in the following chapter. Texture was a crucial factor, finer-textured soils generally having lower pH and higher organic matter contents, although the latter were generally greater closer to the surface. Clay and silt contents were highly correlated, probably reflecting water sorting in the Fayoum, which aided the texture/drainage effect. Drainage (i.e. texture) was apparently very important in the fractionation chemistry of elements influenced by redox-reactions, i.e. Fe and Mn, and elements for which distribution depended upon Fe and Mn oxides (e.g., Zn) to a significant extent. Clay was especially important to the concentration of crystalline and amorphous iron oxides. Cd and Cu showed marked surface accumulation, especially in the exchangeable fractions, for many profiles, probably through pollution. The Cu content of organic matter was strikingly uniform at the Fayoum. Amorphous and crystalline Fe oxides seem to be especially important in the distribution of Zn. Clay Cd, Fe and Zn and, to a lesser extent, Cu and Mn contents were relatively constant, suggesting uniform origins. Chapter 7 describes a pot experiment on the soils using barley as a test crop, aimed at relating uptake to the fractionation results. Interpretation was complicated by a dominant effect of soil salinity. Chapter 8 suggests future related research.

Soil samples from 118 sites on 71 geologic units in southwest Oregon were collected and analyzed to determine the background concentrations of metals in soils of the region. Sites were chosen in areas that were relatively undisturbed by human activities. The U.S. Environmental Protection Agency approved total-recoverable method was used to recover metals from samples for analysis. The twenty six metals analyzed were: Ag, AI, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, La, Li, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, Tl, V and Zn. The Klamath Mountains followed by the Coast Range contain the highest soil concentrations of AI, Ca, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Ni, V and Zn. Soils of the Coastal Plain and High Lava Plains contain the lowest concentrations of these metals. Unusually high soil As concentrations are found at two sites in the Klamath Mountains. All Be and Cd values above laboratory's reporting limits are also from the Klamath Mountains and Coast Range. Concentrations of soil Ba and La are fairly uniform throughout the region. Soil Pb levels are generally low with a few exceptions in the Klamath Mountains, Coast and Cascade Ranges. The region west of the Cascade Range has higher soil Hg contents than in the east. Soil metal concentrations are generally much higher in the region west of the Cascade Range, excluding the Coastal Plain, than in the east with the exception ofNa, because of more ultramafic rocks and a wetter climate. Soil metal concentrations are directly related to soil development with the highest concentrations being found in well developed Alfisols and Ultisols and the lowest concentrations in poorly developed Entisols. Most metals have similar averages and ranges of concentration compared to the rest of the United States (U.S.). Metals with high values compared to the rest of the U.S. are Cr, Co, Cu, Mn and Ni. In general, AI, Co, Cr, Cu, Fe, La, Li, Mg, Na, Ni, and V are concentrated in the B horizon while Ba, Ca, Hg, K, Mn, Pb and Zn are concentrated in the A horizon.

El metabolisme monocarbonat i els elements traça essencials afecten al desenvolupament i resultat de l'embaràs. Es desconeixen els efectes de diversos polimorfismes del metabolisme monocarbonat (MTHFR c.665C>T, BHMT c.716G>A, SLC19A1 c.80G>A i MTRR c.66A>G) durant l'embaràs i la seva possible modulació segons l'estat en folat; i quins factors estan associats amb les concentracions d'elements traça (zinc, coure, seleni i ferro) en la placenta. Aquests aspectes dels esmentats polimorfismes i elements traça s’han estudiat en 617 embarassos del Reus-Tarragona Birth Cohort i 218 placentes. Amb alt estat en folat eritrocitàri a ≤12 setmanes gestacionals (SG), i en folat plasmàtic des de les 15SG, l’MTHFR c.665C>T no va haver tenir cap efecte sobre l'homocisteïna plasmàtica. Els genotips variants de BHMT c.716 tenien menor concentració de dimetilglicina des de la meitat de l'embaràs, i a principis de l'embaràs si l'estat en folat plasmàtic era alt. Homozigots variants de MTRR c.66 van tenir major concentració d'homocisteïna plasmàtica a principis de l'embaràs, però això no es veia en els tercils extrems de folat plasmàtic. Les concentracions en placenta de zinc, coure i seleni estaven positivament correlacionades entre si, i negativament associades al pes al néixer. Les fumadores durant l'embaràs van tenir majors concentracions de coure i seleni. La ingesta d'aquests elements traça de la dieta i/o suplements no es va associar amb les seves concentracions en placenta. Les concentracions plasmàtiques de cobalamina a ≤12SG i d'homocisteïna al part es van associar negativa i positivament, respectivament, amb les de coure en la placenta. L'al•lel normal de MTHFR c.665 del neonat i la concentració de coure en la placenta es van associar positivament amb el creixement intrauterí restringit. Els polimorfismes i la seva modulació segons l'estat en folat, i elements traça en placenta estudiats estan associats amb canvis en el metabolisme i resultat de l'embaràs.
El metabolismo monocarbonado y los elementos traza esenciales afectan al desarrollo y resultado del embarazo. Se desconocen los efectos de varios polimorfismos del metabolismo monocarbonado (MTHFR c.665C>T, BHMT c.716G>A, SLC19A1 c.80G>A y MTRR c.66A>G) en el embarazo y su posible modulación según el estado en folato; y qué factores están asociados con las concentraciones de elementos traza (zinc, cobre, selenio y hierro) en la placenta. Se estudiaron estos aspectos de dichos polimorfismos y elementos traza en 617 embarazos del Reus-Tarragona Birth Cohort y 218 placentas. Con alto estado en folato eritrocitario a ≤12 semanas gestacionales (SG), y en folato plasmático desde las 15SG no se observó el efecto de MTHFR c.665C>T en la homocisteína plasmática. Genotipos variantes de BHMT c.716 tuvieron menor concentración de dimetilglicina desde la mitad del embarazo, y esto ocurrió también a principios del embarazo si el estado en folato plasmático era alto. Homozigotos variantes de MTRR c.66 tuvieron mayor concentración de homocisteína plasmática a principios del embarazo, pero esto no ocurría en los terciles extremos de folato plasmático. Las concentraciones en placenta de zinc, cobre y selenio estaban positivamente correlacionadas entre sí, y negativamente asociadas al peso al nacer. Fumadoras durante el embarazo tuvieron mayores concentraciones de cobre y selenio. La ingesta de estos elementos traza de la dieta y/o suplementos no se asoció con sus concentraciones en placenta. Las concentraciones plasmáticas de cobalamina a ≤12SG y de homocisteína en el parto se asociaron negativa y positivamente, respectivamente, con las de cobre en la placenta. El alelo normal de MTHFR c.665 del neonato y la concentración de cobre en la placenta se asociaron positivamente con el crecimiento intrauterino restringido. Los polimorfismos y su modulación según el estado en folato, y elementos traza en placenta estudiados están asociados con cambios en el metabolismo y resultado del embarazo.
One carbon metabolism and essential trace elements affect foetal development and pregnancy outcome. The effects of several highly prevalent one carbon metabolism polymorphisms (MTHFR c.665C>T, BHMT c.716G>A, SLC19A1 c.80G>A and MTRR c.66A>G) in pregnancy and their possible modulation by folate status, and which factors are associated with the placenta trace element concentrations (zinc, copper, selenium and iron), are unknown. These aspects of the aforementioned polymorphisms and trace elements were studied in 617 pregnancies of the Reus-Tarragona Birth Cohort and 218 placentas. With high erythrocyte folate status at ≤12 gestational weeks (GW) and with high plasma folate status from 15GW on, the homocysteine-enhancing effect of MTHFR c.665C>T was not observed. Lower plasma dimethylglycine in BHMT c.716 variant genotypes was found at mid-late pregnancy, and this was also true for early pregnancy if plasma folate status was high. MTRR c.66 variant homozygotes had higher plasma homocysteine concentration at early pregnancy, and after plasma folate status stratification this was not observed in the extreme tertiles. Placenta concentrations of zinc, copper and selenium were positively correlated, and negatively associated with birth weight. Smoking during pregnancy was associated with higher copper and selenium concentrations. Intake of these trace elements from food and/or supplements was not associated with their concentrations in placenta. Plasma cobalamin at ≤12GW and homocysteine at labour were negatively and positively, respectively, associated with placenta copper concentrations. MTHFR c.665 normal allele in the neonate and placenta copper concentration were positively associated with intrauterine growth restriction. These studied polymorphisms and their modulation by folate status, and the placenta trace elements, are associated with metabolic changes and pregnancy outcome.

Innovative means and methods were tested to develop an economical, pragmatic and environmentally sustainable soil remediation process for heavy metal contaminated soils. An unsaturated-flow soil washing procedure was devised to dissolve the soil-bound toxic heavy metals; the latter were extracted by a chemical washing solution that percolated through the soil matrix. Subsequently, the leached toxic heavy metals were selectively concentrated, by a chemical precipitation process, into a solid waste. Thereby, a fraction of the spent ethylenediaminetetraacetic acid (EDTA), within the washing and rinsing leachate, was theoretically regenerated and recycle-ready.
The unsaturated-flow washing procedure was perfected by applying different treatments to a soil from a secure landfill. This soil was contaminated with Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, S and Zn. The major contaminants were Fe, Pb, Zn, S, Cu and Mn, making up 25, 1.9, 1.0, 0.4, 0.4 and 0.2%wt of the soil. The extraction responses of the contaminants and those of Al, Ca, Mg and P were established for citric acid (0.5 M) and different molarities of diammonium EDTA ((NH4)2EDTA). The DOW Chemical Company supplied the (NH4)2EDTA (i.e. VERSENE), a 1.37M industrial cleaner, which roughly costs $1.85kg-1 in bulk. The affordability of VERSENE was a pre-condition for hoping to satisfy the economical feasibility of remediating trace metal contaminated soils.
Ultimately, the developed unsaturated-flow washing procedure was tested in a pilot-scale experiment, for its ability to remediate a soil from an abandoned car battery recycling facility. The latter soil was severely contaminated with Pb (3.9%wt). Drip irrigation was used to apply (NH4) 2EDTA and water-rinsing solutions to the surface of soil heaps that rested atop an impermeable barrier, which permitted the retrieval of the leachate. A cumulative EDTA input to the soil of 10.6% wt extracted 49.4% of the total Pb content of the soil. Alternatively, readily biodegradable citric acid barely extracted 2.2% of the total Pb content of the soil, for a cumulative input of 18.1% weight of soil. Different treatments were tested for their effectiveness in concentrating the leached toxic heavy metals into a solid waste. The Pb was best precipitated with Na2S alone, as it provided the most concentrated solid toxic waste.
The environmental sustainability of remediating trace metal contaminated soils was thoroughly examined, as per the amounts of chemical entrants and toxic waste by-products, and per the post-treatment leaching of toxic levels of the remaining and potentially toxic trace metals. (Abstract shortened by UMI.)

An investigation of heavy metal concentrations in sediments from Coxs River catchment, a tributary of the Hawkesbury-Nepean River system, has been undertaken. A number of digestion methods were assessed for the determination of Pb, Cu, Cd, Zn, Ni, Mn, Fe, Co and Cr in reference materials by flame AAS. The method that produced the best recovery is reverse aqua regia, HNO3-HC1 with ultrasonification followed by heating on a hotplate. Based on analysis of sediments from 133 sites, background concentrations were established. Elevated heavy metal concentrations were recorded in some samples. The three most polluted areas were investigated for heavy metal associations and distributions. Metal bioavailability was assessed from sediment samples by using selective extraction techniques. The association of heavy metals with different solid phases was assessed by a sequential extraction technique involving a series of extraction reagents. Pd, Cu, Fe and Cr were mainly associated with Fe/Mn oxides and organic matter plus sulphide phases. While Cd, Zn, Ni and Co which behave similarly were extracted from each step, the largest percentages of these metals were found in Fe/Mn oxides and organic matter phases. Mn was different to other metals, in that it predominantly associated with the ion exchangeable form.
Master of Science (Hons)

This paper presents the results of coal gasification in a fluidized bed test rig of Xuzhou bituminous coal. The diameter of the fluidized bed combustor is 0.1m and the height is 4.22m. The bed temperature is maintained by a method of high temperature flue gas interline heating to overcome high heat losses associated with a oil burner. Test results are reported for variations in the bed temperature, air to coal, steam to coal and Ca to S ratio and their influence on gas yields and desulphurization efficiency. The distribution of polycyclic aromatic hydrocarbons (PAHs) and heavy metal trace elements into the char and syngas are also presented. The molar contents for CH4 and H2 in the coal syngas are found to decrease with increasing air to coal feed ratio from 2.5 to 5, while the content of CO shows little variation. Increasing the steam to coal feed ratio from 0.4 to 0.65 results in all three of the main gas components measured to form a local maximum content at a steam/coal feed ratio of 0.55. The efficiency of desulphurization improves as the ratio of Ca to S, air to coal and the bed temperature are increased, while decreasing with increasing steam to coal feed ratios. The volatile trace element species in decreasing order of relative mass ratio released into the gas phase are Hg, Se, As, Co, Cr, Cd, Cu, and Zn. Besides Hg, Se, and As, for all other trace heavy metals the majority of their mass distribution remains within the char with the proportion contained within char always greater than their combined yields in the coal syngas and slag. The total PAHs in the coal syngas is greater than that contained in the original coal and this indicates that PAHs are formed during the coal gasification process.

The behavior of 20 trace elements (As, B, Ba, Cd, Co, Cr, Cu, Hg, Li, Mn, Mo, Ni, P, Pb, Sb, Se, Sn, Tl, V, Zn) and 8 major and minor elements (Al, Ca, Fe, K, Mg, Na, Si, Ti) during the combustion of high ash content lignite with and without limestone addition have been investigated in the 0.3 MWt Middle East Technical University (METU) Atmospheric Bubbling Fluidized Bed Combustor (ABFBC) Test Rig. Experiments were performed without fines recycle. Inert bed material utilized in the experiments was bed ash obtained previously from the combustion of the same lignite without limestone addition in the same test rig. Concentrations of trace elements in coal, limestone, bottom ash, cyclone ash and filter ash were determined by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Measurements show that the distribution of major and minor elements follows the ash split between the bottom ash and fly ash and that the major proportion of most of the trace elements (As, Ba, Cr, Hg, Li, Mo, Ni, Sn, V, Zn) are recovered in fly ash. Comparisons between the trace element partitioning of the runs with and without limestone addition reveal that addition of limestone shifts the partitioning of Ba, Cr, Hg, Mo, Ni, Sn, V, Zn from bottom ash to fly ash.

Based on the Modified Geo-chemical Enrichment Factor (MGEF), the contents of As, Cd, Co, Cr, Cu, Mn, Hg, Pb, V, Se, Sr, Zn in coal and coal char were analyzed by using Hydride Generation-Atomic Fluorescence Spectrometry (HG-AFS) and Inductively Couple Plasma-atomic Emission Spectroscopy (ICP-AES). Limestone, dolomite and sodium carbonate were studied to control trace elements during coal gasification. Different additives show different performances in the control of trace elements. The adsorbing capacity of coal char to all of trace elements enhances when coal is mixed with limestone and dolomite. Chemical adsorption and physical adsorption of lime, which is decomposition product of limestone under high gasification temperature, are both important for As, Co, Cr, Se and Zn. The effects of limestone on Cd, Cu, Hg, Pb, V and Sr are merely caused by physical adsorption of CaO and the adsorbing capacity to Cd, Cu, V is much stronger than those to Hg, Pb, Sr. Dolomite has stronger adsorbing capacity to most of elements (except Cu, Se, Sr) than limestone. Addition of Na2CO3 decreases the MGEFs of As, Cd, Cr, Pb and Se while increases the MGEFs of Zn in coal char. Na2CO3 has little effect on the MGEFs of Co, Cu, Hg, V and Sr in coal char.

Heavy minerals (HMs) are minerals with a specific gravity greater than 2.9 g/cm3. They are commonly highly resistant to physical and chemical weathering, and therefore persist in sediments as lasting indicators of the (former) presence of the rocks they formed in. The presence/absence of certain HMs, their associations with other HMs, their concentration levels, and the geochemical patterns they form in maps or 3D models can be indicative of geological processes that contributed to their formation. Furthermore trace element and isotopic analyses of HMs have been used to vector to mineralisation or constrain timing of geological processes. The positive role of HMs in mineral exploration is well established in other countries, but comparatively little understood in Australia. Here we present the results of a pilot project that was designed to establish, test and assess a workflow to produce a HM map (or atlas of maps) and dataset for Australia. This would represent a critical step in the ability to detect anomalous HM patterns as it would establish the background HM characteristics (i.e., unrelated to mineralisation). Further the extremely rich dataset produced would be a valuable input into any future machine learning/big data-based prospectivity analysis. The pilot project consisted in selecting ten sites from the National Geochemical Survey of Australia (NGSA) and separating and analysing the HM contents from the 75-430 µm grain-size fraction of the top (0-10 cm depth) sediment samples. A workflow was established and tested based on the density separation of the HM-rich phase by combining a shake table and the use of dense liquids. The automated mineralogy quantification was performed on a TESCAN® Integrated Mineral Analyser (TIMA) that identified and mapped thousands of grains in a matter of minutes for each sample. The results indicated that: (1) the NGSA samples are appropriate for HM analysis; (2) over 40 HMs were effectively identified and quantified using TIMA automated quantitative mineralogy; (3) the resultant HMs’ mineralogy is consistent with the samples’ bulk geochemistry and regional geological setting; and (4) the HM makeup of the NGSA samples varied across the country, as shown by the mineral mounts and preliminary maps. Based on these observations, HM mapping of the continent using NGSA samples will likely result in coherent and interpretable geological patterns relating to bedrock lithology, metamorphic grade, degree of alteration and mineralisation. It could assist in geological investigations especially where outcrop is minimal, challenging to correctly attribute due to extensive weathering, or simply difficult to access. It is believed that a continental-scale HM atlas for Australia could assist in derisking mineral exploration and lead to investment, e.g., via tenement uptake, exploration, discovery and ultimately exploitation. As some HMs are hosts for technology critical elements such as rare earth elements, their systematic and internally consistent quantification and mapping could lead to resource discovery essential for a more sustainable, lower-carbon economy.

1.1 Macroeconomic summary Economic recovery has consistently outperformed the technical staff’s expectations following a steep decline in activity in the second quarter of 2020. At the same time, total and core inflation rates have fallen and remain at low levels, suggesting that a significant element of the reactivation of Colombia’s economy has been related to recovery in potential GDP. This would support the technical staff’s diagnosis of weak aggregate demand and ample excess capacity. The most recently available data on 2020 growth suggests a contraction in economic activity of 6.8%, lower than estimates from January’s Monetary Policy Report (-7.2%). High-frequency indicators suggest that economic performance was significantly more dynamic than expected in January, despite mobility restrictions and quarantine measures. This has also come amid declines in total and core inflation, the latter of which was below January projections if controlling for certain relative price changes. This suggests that the unexpected strength of recent growth contains elements of demand, and that excess capacity, while significant, could be lower than previously estimated. Nevertheless, uncertainty over the measurement of excess capacity continues to be unusually high and marked both by variations in the way different economic sectors and spending components have been affected by the pandemic, and by uneven price behavior. The size of excess capacity, and in particular the evolution of the pandemic in forthcoming quarters, constitute substantial risks to the macroeconomic forecast presented in this report. Despite the unexpected strength of the recovery, the technical staff continues to project ample excess capacity that is expected to remain on the forecast horizon, alongside core inflation that will likely remain below the target. Domestic demand remains below 2019 levels amid unusually significant uncertainty over the size of excess capacity in the economy. High national unemployment (14.6% for February 2021) reflects a loose labor market, while observed total and core inflation continue to be below 2%. Inflationary pressures from the exchange rate are expected to continue to be low, with relatively little pass-through on inflation. This would be compatible with a negative output gap. Excess productive capacity and the expectation of core inflation below the 3% target on the forecast horizon provide a basis for an expansive monetary policy posture. The technical staff’s assessment of certain shocks and their expected effects on the economy, as well as the presence of several sources of uncertainty and related assumptions about their potential macroeconomic impacts, remain a feature of this report. The coronavirus pandemic, in particular, continues to affect the public health environment, and the reopening of Colombia’s economy remains incomplete. The technical staff’s assessment is that the COVID-19 shock has affected both aggregate demand and supply, but that the impact on demand has been deeper and more persistent. Given this persistence, the central forecast accounts for a gradual tightening of the output gap in the absence of new waves of contagion, and as vaccination campaigns progress. The central forecast continues to include an expected increase of total and core inflation rates in the second quarter of 2021, alongside the lapse of the temporary price relief measures put in place in 2020. Additional COVID-19 outbreaks (of uncertain duration and intensity) represent a significant risk factor that could affect these projections. Additionally, the forecast continues to include an upward trend in sovereign risk premiums, reflected by higher levels of public debt that in the wake of the pandemic are likely to persist on the forecast horizon, even in the context of a fiscal adjustment. At the same time, the projection accounts for the shortterm effects on private domestic demand from a fiscal adjustment along the lines of the one currently being proposed by the national government. This would be compatible with a gradual recovery of private domestic demand in 2022. The size and characteristics of the fiscal adjustment that is ultimately implemented, as well as the corresponding market response, represent another source of forecast uncertainty. Newly available information offers evidence of the potential for significant changes to the macroeconomic scenario, though without altering the general diagnosis described above. The most recent data on inflation, growth, fiscal policy, and international financial conditions suggests a more dynamic economy than previously expected. However, a third wave of the pandemic has delayed the re-opening of Colombia’s economy and brought with it a deceleration in economic activity. Detailed descriptions of these considerations and subsequent changes to the macroeconomic forecast are presented below. The expected annual decline in GDP (-0.3%) in the first quarter of 2021 appears to have been less pronounced than projected in January (-4.8%). Partial closures in January to address a second wave of COVID-19 appear to have had a less significant negative impact on the economy than previously estimated. This is reflected in figures related to mobility, energy demand, industry and retail sales, foreign trade, commercial transactions from selected banks, and the national statistics agency’s (DANE) economic tracking indicator (ISE). Output is now expected to have declined annually in the first quarter by 0.3%. Private consumption likely continued to recover, registering levels somewhat above those from the previous year, while public consumption likely increased significantly. While a recovery in investment in both housing and in other buildings and structures is expected, overall investment levels in this case likely continued to be low, and gross fixed capital formation is expected to continue to show significant annual declines. Imports likely recovered to again outpace exports, though both are expected to register significant annual declines. Economic activity that outpaced projections, an increase in oil prices and other export products, and an expected increase in public spending this year account for the upward revision to the 2021 growth forecast (from 4.6% with a range between 2% and 6% in January, to 6.0% with a range between 3% and 7% in April). As a result, the output gap is expected to be smaller and to tighten more rapidly than projected in the previous report, though it is still expected to remain in negative territory on the forecast horizon. Wide forecast intervals reflect the fact that the future evolution of the COVID-19 pandemic remains a significant source of uncertainty on these projections. The delay in the recovery of economic activity as a result of the resurgence of COVID-19 in the first quarter appears to have been less significant than projected in the January report. The central forecast scenario expects this improved performance to continue in 2021 alongside increased consumer and business confidence. Low real interest rates and an active credit supply would also support this dynamic, and the overall conditions would be expected to spur a recovery in consumption and investment. Increased growth in public spending and public works based on the national government’s spending plan (Plan Financiero del Gobierno) are other factors to consider. Additionally, an expected recovery in global demand and higher projected prices for oil and coffee would further contribute to improved external revenues and would favor investment, in particular in the oil sector. Given the above, the technical staff’s 2021 growth forecast has been revised upward from 4.6% in January (range from 2% to 6%) to 6.0% in April (range from 3% to 7%). These projections account for the potential for the third wave of COVID-19 to have a larger and more persistent effect on the economy than the previous wave, while also supposing that there will not be any additional significant waves of the pandemic and that mobility restrictions will be relaxed as a result. Economic growth in 2022 is expected to be 3%, with a range between 1% and 5%. This figure would be lower than projected in the January report (3.6% with a range between 2% and 6%), due to a higher base of comparison given the upward revision to expected GDP in 2021. This forecast also takes into account the likely effects on private demand of a fiscal adjustment of the size currently being proposed by the national government, and which would come into effect in 2022. Excess in productive capacity is now expected to be lower than estimated in January but continues to be significant and affected by high levels of uncertainty, as reflected in the wide forecast intervals. The possibility of new waves of the virus (of uncertain intensity and duration) represents a significant downward risk to projected GDP growth, and is signaled by the lower limits of the ranges provided in this report. Inflation (1.51%) and inflation excluding food and regulated items (0.94%) declined in March compared to December, continuing below the 3% target. The decline in inflation in this period was below projections, explained in large part by unanticipated increases in the costs of certain foods (3.92%) and regulated items (1.52%). An increase in international food and shipping prices, increased foreign demand for beef, and specific upward pressures on perishable food supplies appear to explain a lower-than-expected deceleration in the consumer price index (CPI) for foods. An unexpected increase in regulated items prices came amid unanticipated increases in international fuel prices, on some utilities rates, and for regulated education prices. The decline in annual inflation excluding food and regulated items between December and March was in line with projections from January, though this included downward pressure from a significant reduction in telecommunications rates due to the imminent entry of a new operator. When controlling for the effects of this relative price change, inflation excluding food and regulated items exceeds levels forecast in the previous report. Within this indicator of core inflation, the CPI for goods (1.05%) accelerated due to a reversion of the effects of the VAT-free day in November, which was largely accounted for in February, and possibly by the transmission of a recent depreciation of the peso on domestic prices for certain items (electric and household appliances). For their part, services prices decelerated and showed the lowest rate of annual growth (0.89%) among the large consumer baskets in the CPI. Within the services basket, the annual change in rental prices continued to decline, while those services that continue to experience the most significant restrictions on returning to normal operations (tourism, cinemas, nightlife, etc.) continued to register significant price declines. As previously mentioned, telephone rates also fell significantly due to increased competition in the market. Total inflation is expected to continue to be affected by ample excesses in productive capacity for the remainder of 2021 and 2022, though less so than projected in January. As a result, convergence to the inflation target is now expected to be somewhat faster than estimated in the previous report, assuming the absence of significant additional outbreaks of COVID-19. The technical staff’s year-end inflation projections for 2021 and 2022 have increased, suggesting figures around 3% due largely to variation in food and regulated items prices. The projection for inflation excluding food and regulated items also increased, but remains below 3%. Price relief measures on indirect taxes implemented in 2020 are expected to lapse in the second quarter of 2021, generating a one-off effect on prices and temporarily affecting inflation excluding food and regulated items. However, indexation to low levels of past inflation, weak demand, and ample excess productive capacity are expected to keep core inflation below the target, near 2.3% at the end of 2021 (previously 2.1%). The reversion in 2021 of the effects of some price relief measures on utility rates from 2020 should lead to an increase in the CPI for regulated items in the second half of this year. Annual price changes are now expected to be higher than estimated in the January report due to an increased expected path for fuel prices and unanticipated increases in regulated education prices. The projection for the CPI for foods has increased compared to the previous report, taking into account certain factors that were not anticipated in January (a less favorable agricultural cycle, increased pressure from international prices, and transport costs). Given the above, year-end annual inflation for 2021 and 2022 is now expected to be 3% and 2.8%, respectively, which would be above projections from January (2.3% and 2,7%). For its part, expected inflation based on analyst surveys suggests year-end inflation in 2021 and 2022 of 2.8% and 3.1%, respectively. There remains significant uncertainty surrounding the inflation forecasts included in this report due to several factors: 1) the evolution of the pandemic; 2) the difficulty in evaluating the size and persistence of excess productive capacity; 3) the timing and manner in which price relief measures will lapse; and 4) the future behavior of food prices. Projected 2021 growth in foreign demand (4.4% to 5.2%) and the supposed average oil price (USD 53 to USD 61 per Brent benchmark barrel) were both revised upward. An increase in long-term international interest rates has been reflected in a depreciation of the peso and could result in relatively tighter external financial conditions for emerging market economies, including Colombia. Average growth among Colombia’s trade partners was greater than expected in the fourth quarter of 2020. This, together with a sizable fiscal stimulus approved in the United States and the onset of a massive global vaccination campaign, largely explains the projected increase in foreign demand growth in 2021. The resilience of the goods market in the face of global crisis and an expected normalization in international trade are additional factors. These considerations and the expected continuation of a gradual reduction of mobility restrictions abroad suggest that Colombia’s trade partners could grow on average by 5.2% in 2021 and around 3.4% in 2022. The improved prospects for global economic growth have led to an increase in current and expected oil prices. Production interruptions due to a heavy winter, reduced inventories, and increased supply restrictions instituted by producing countries have also contributed to the increase. Meanwhile, market forecasts and recent Federal Reserve pronouncements suggest that the benchmark interest rate in the U.S. will remain stable for the next two years. Nevertheless, a significant increase in public spending in the country has fostered expectations for greater growth and inflation, as well as increased uncertainty over the moment in which a normalization of monetary policy might begin. This has been reflected in an increase in long-term interest rates. In this context, emerging market economies in the region, including Colombia, have registered increases in sovereign risk premiums and long-term domestic interest rates, and a depreciation of local currencies against the dollar. Recent outbreaks of COVID-19 in several of these economies; limits on vaccine supply and the slow pace of immunization campaigns in some countries; a significant increase in public debt; and tensions between the United States and China, among other factors, all add to a high level of uncertainty surrounding interest rate spreads, external financing conditions, and the future performance of risk premiums. The impact that this environment could have on the exchange rate and on domestic financing conditions represent risks to the macroeconomic and monetary policy forecasts. Domestic financial conditions continue to favor recovery in economic activity. The transmission of reductions to the policy interest rate on credit rates has been significant. The banking portfolio continues to recover amid circumstances that have affected both the supply and demand for loans, and in which some credit risks have materialized. Preferential and ordinary commercial interest rates have fallen to a similar degree as the benchmark interest rate. As is generally the case, this transmission has come at a slower pace for consumer credit rates, and has been further delayed in the case of mortgage rates. Commercial credit levels stabilized above pre-pandemic levels in March, following an increase resulting from significant liquidity requirements for businesses in the second quarter of 2020. The consumer credit portfolio continued to recover and has now surpassed February 2020 levels, though overall growth in the portfolio remains low. At the same time, portfolio projections and default indicators have increased, and credit establishment earnings have come down. Despite this, credit disbursements continue to recover and solvency indicators remain well above regulatory minimums. 1.2 Monetary policy decision In its meetings in March and April the BDBR left the benchmark interest rate unchanged at 1.75%.