Variations In Trace Element Contents Research Articles

Oblique continental collision and the formation of syn-collisional A-type granites: insights from the Early Jurassic Baoji granite suite in the Qinling orogenic belt, central China

ABSTRACT A-type granites are conventionally interpreted to be formed in late post-collisional or anorogenic settings. However, we firstly identified an Early Jurassic syn-collisional A-type granite suite in the Qinling orogenic belt: the Baoji granite suite. A comprehensive investigation into its mineralogical, petrological, geochronological, and geochemical characteristics can shed light on the genesis of syn-collisional A-type granites and geodynamic evolution of collisional orogeny. The Baoji granite suite contains two types of rocks: (1) A-type granites including biotite syenite, coarse-grained, porphyritic, and fine-grained syenogranites, and alkali-feldspar granite, and (2) magnesian monzodiorite; both types are coeval, with zircon U–Pb ages of ca. 190 Ma. The A-type granites yield A1-type trace element signatures and large variations in trace element contents, with Ba contents of 16.9–762 ppm, Sr of 11.0–211 ppm, Rb of 193–645 ppm, and Eu of 0.08–1.24 ppm. Their radiogenic isotope compositions (87Sr/86Sri = 0.70631–0.70637; εNd = −5.18 to −3.84; εHf = −5.01 to +2.76) are similar, and overlap those of Neoproterozoic OIB-like basic volcanics from the South Qinling belt. These characteristics show that the A-type granites originated from the anatexis of OIB-like lower crust and underwent fractional crystallization in a silicic magma reservoir. The monzodiorite has low SiO2 contents (49.82–53.29 wt.%) and enriched radiogenic isotopic compositions (87Sr/86Sri = 0.70554–0.70638; εNd = −11.0 to −5.28) contains abundant hornblende and biotite (~40%), and exhibits evidence of magma mingling. It also contains two groups of zircon: pristine and unzoned zircon that yields negative Hf isotope compositions (εHf = −9.42 to −3.14), and xenocrystic zircon that yields similar Hf isotope compositions (εHf = −3.54 to +1.85) to the A-type granites. These characteristics demonstrate that the monzodiorite was derived from the differentiation of basaltic partial melts of an enriched mantle source, and mingled with the A-type granitic magma during its ascent and emplacement into a silicic magma reservoir. Along with regional records of the Early Jurassic magmatism, deformation, metamorphism, and sedimentation, the genetic models for the Baoji A-type granites and monzodiorite suggest that the Middle Triassic to Early Jurassic oblique continental collision (ca. 230–190 Ma) produced coupled EW-trending strike-slip and NE-trending extensional faults at crustal levels and Rayleigh–Taylor (gravitational) convective instabilities at mantle depths in the Qinling orogenic belt, which controlled the production of the syn-collisional A-type granite suite. Our work also indicates that the A-type granites can be formed in syn-collisional setting in response to oblique continental collision and the resultant slow foundering of a high-density lithospheric root; therefore, we suggest that the syn-collisional A-type granites are evidence for oblique continental collision.

Improvement of the chemical properties of waste rock deposits at the Agbaou gold mine by the legume Pueraria phasoeloïdes (Center-west Côte d'Ivoire)

Objective: To assess the effects of the legume (Pueraria phasoeloïdes) on the chemical parameters of the waste rock soils (saprolites) at the Agbaou gold mine, in the center-west of Côte d’Ivoire. Methodology and results: Soil samples were taken using the systematic sampling method at regular intervals of 20 m on the ramps and at 20 cm soil depth, using an auger during two consecutive sampling campaigns (2016-2017 and 2017-2018). The geometric coordinates of the sampling points were obtained using a GPS Garming CSX60 type. A total of 20 composite samples were made from 80 collected soil samples. Chemical analyzes were carried out on soil samples obtained. The results show that the contents of total organic carbon (TOC), total organic nitrogen (Nt), the C: N ratio and the pH values of the soils, under Pueraria phaseoloïdes legume were significantly improved between the ramps and between the two campaigns (p <0.05). Conversely, (CEC, exchangeable bases, (Ca2+, Mg2+ and K+) and phosphorus contents decreased significantly (p <0.001) between the ramps and the two campaigns. This reflects the improving effect of the legume on the chemical parameters of the soils. However, variations in trace element content between ramps and across campaigns did not show any significant improvement (p> 0.05).

Serum Levels of Selenium, Zinc, Copper, Manganese, and Iron in Prostate Cancer Patients

Backgrounds: Variations of trace element contents may be associated with several diseases including metabolic disorders, cellular growth disturbance, mutation and tumorigenesis. Prostate cancer is the second most common male cancer worldwide and stand fifth most common male cancer in Saudi Arabia. Objective: In the present study, Serum levels of selenium, zinc, copper, manganese, and iron were measured in patients with BPH and prostate cancer aiming to explore the association between these elements and prostate cancer. Patients and Methods: The study included 40 newly diagnosed prostate cancer patients, 22 patients with BPH and 30 healthy male subjects. All participant groups had similar socio-economic levels. Fasting blood samples were collected from all subjects and before any intervention for the patients. Serum PSA concentrations were analyzed by ELIZA and trace elements Se, Zn, Cu, Mn and Fe were measured by ICP-MS. Results: Serum Se, Zn, and Mn levels of prostate cancer patients were significantly decreased compared to control groups. The levels of serum Cu and Fe were significantly higher in prostate cancer patients than in control groups. Conclusion: In the present study, an association was noticed between serum trace elements disturbance and prostate cancer. The decreased levels of Se, Zn, and Mn, and increased Cu and Fe levels may play significant roles in the initiation of prostate cancer. However, future prospective studies on the causes of trace elements alteration in prostate cancer patients are needed as well as to illustrate the relation between different prostate cancer stages and trace elements concentrations.

Post-crystallization alteration of natural uraninites: Implications for dating, tracing, and nuclear forensics

Abstract This study presents systematic chemical (U, Pb, Ca, Si, Fe) mapping coupled with in situ analyses of major, minor and trace elements, U/Pb, 207Pb/206Pb, and O isotopic compositions of natural uraninites (UO2) from two samples of the high-grade uranium ore from the Cigar Lake unconformity-related uranium deposit (Athabasca Basin, Saskatchewan, Canada). The studied uraninites are characterized by major chemical and isotopic heterogeneities expressed at small scale (µm to tens of µm), from almost pristine zones to strongly altered material. The 206Pb/238U and 207Pb/235U ratios of the different areas are widely spread and depict two similar and well-defined Discordia, providing an upper intercept age of crystallization at ca. 1300 Ma (1299 ± 4 and 1308 ± 14 Ma, respectively) and lower intercepts at 38 ± 13 and 72 ± 22 Ma, respectively. The freshest areas are characterized by sub-concordant 206Pb/238U and 207Pb/235U ratios, identical chemical compositions and similar very low δ18O values (−39.3 to −31.4‰). These data indicate that the two uraninites both crystallized at ca. 1300 Ma, from the same fluid and under identical physico-chemical conditions. Alteration is characterized by (i) the progressive incorporation of Ca, Si, and Fe, reaching several wt.%, which substitute to the radiogenic Pb and cause a progressive decrease in the Pb/U isotopic ratios. The radiogenic Pb is also substituted by water during the alteration, (ii) concomitant variations in trace element contents (As, Mn, V, LREEs, Sr, Th, B, Ba, Nb, for example) and (iii) heavier δ18O signatures (−22.5 to −8.91‰), typical of meteoric waters, in the altered zones. This combined approach demonstrates that fluid-driven post-crystallization exchanges affected each uraninite during recent fluid flow events (ca. 40 Ma and 70 Ma respectively). The relatively high dispersion of the Pb/U ratios in relation to the Discordia for both samples is considered as linked to a local (nm to µm-scale) differential mobility between lead and uranium within the uranium oxides. The chemical changes affecting elements previously considered as immobile in uraninite, such as REEs, indicate that these elements are not preserved during the post-crystallization alteration process studied here. Alteration processes may therefore have a major impact on the classical geochemical tracers, such as REE patterns or LREE/HREE ratios, currently used in nuclear forensic studies. The isotopic and chemical tracers currently used to track back the origin, age and history of natural uraninites should therefore be considered with a high degree of caution to avoid misleading and erroneous conclusions. Moreover, the comparison of calculated U-Th-Pb chemical, 207Pb/206Pb, and Pb/U isotopic ages shows that the use of age clustering for determining U-Th-Pb chemical ages and 206Pb/207Pb ages is not appropriate for constraining crystallization stage(s) of altered uraninites and for deciphering the different fluid events that potentially altered or recrystallized the uraninites over time. This study also indicates that estimation of the crystallization age of uraninite from substitution trends of Pb to Ca is not applicable to unconformity-related U deposits and results in overestimated ages because of an initial integration of calcium in the uraninite lattice at the time of crystallization.

Open-water and under-ice seasonal variations in trace element content and physicochemical associations in fluvial bed sediment.

Across the circumpolar world, intensive anthropogenic activities in the southern reaches of many large, northward-flowing rivers can cause sediment contamination in the downstream depositional environment. The influence of ice cover on concentrations of inorganic contaminants in bed sediment (i.e., sediment quality) is unknown in these rivers, where winter is the dominant season. A geomorphic response unit approach was used to select hydraulically diverse sampling sites across a northern test-case system, the Slave River and delta (Northwest Territories, Canada). Surface sediment samples (top 1 cm) were collected from 6 predefined geomorphic response units (12 sites) to assess the relationships between bed sediment physicochemistry (particle size distribution and total organic carbon content) and trace element content (mercury and 18 other trace elements) during open-water conditions. A subset of sites was resampled under-ice to assess the influence of season on these relationships and on total trace element content. Concentrations of the majority of trace elements were strongly correlated with percent fines and proxies for grain size (aluminum and iron), with similar trace element grain size/grain size proxy relationships between seasons. However, finer materials were deposited under ice with associated increases in sediment total organic carbon content and the concentrations of most trace elements investigated. The geomorphic response unit approach was effective at identifying diverse hydrological environments for sampling prior to field operations. Our data demonstrate the need for under-ice sampling to confirm year-round consistency in trace element-geochemical relationships in fluvial systems and to define the upper extremes of these relationships. Whether contaminated or not, under-ice bed sediment can represent a "worst-case" scenario in terms of trace element concentrations and exposure for sediment-associated organisms in northern fluvial systems. Environ Toxicol Chem 2017;36:2916-2924. © 2017 SETAC.

Seasonal variations of trace element contents in leaves and bark of horse chestnut (Aesculus hippocastanum L.) in urban and industrial regions in Serbia

In this study, we examined the ability of horse chestnut (Aesculus hippocastanum L.) to capture heavy metals, and whether its capacity to absorb metals from soil is associated with surrounding ecological characteristics and sources of pollution. We studied the seasonal accumulation of B, Cu, Sr and Zn in leaves and bark, and the chlorophyll content in the common deciduous tree Aesculus hippocastanum L. in four urban parks in Pancevo, Smederevo, Obrenovac and Belgrade (Serbia) affected by different anthropogenic activities. The research included plants from a control site located within the zone of a former oak forest. Our findings suggest that there are potential ecological risks around Smederevo, Belgrade and Obrenovac due to elevated concentrations of B and Zn relative to the average concentrations described for worldwide soils, as well as national regulations. Substantial and toxic foliar accumulation of B was observed in Smederevo and Belgrade, and of Sr in both plant tissues at all sites. However, the Cu and Zn contents in leaves were not enough to meet the physiological needs of plants. Chlorophyll a and the total carotenoid content peaked in August under the most unfavorable conditions of the year, which may be considered as an adaptive mechanism. The obtained results showed the remarkable complexity of environmental conditions and the difficulties A. hippocastanum, as a species, has to overcome. Under conditions of different types of urban and industrial pollution, A. hippocastanum showed great element accumulation potential and could be regarded as both an accumulator and a response indicator, since its leaves are quite susceptible to damage.

Sedimentary Environment of the Early Ordovician in Danzhai, Guizhou

This study analyzes the variations in trace element contents and ratios, the distribution patterns of rare earth elements, and the sedimentary environment and its evolution in the Early Ordovician. In particular, the analysis is based on measured section of the Qingjiang Village located in Nangao Town, Danzhai County, Guizhou Province. The analysis also considers thin sections and the characteristics of C, O isotopes. The lower part of the Tongzi Formation has a simple lithology and mainly consists of light gray to gray thin-medium bedded muddy dolomite and dolomicrite with a few dolarenites and dolorudites. The upper part of this formation includes gray thin-medium bedded fine crystalline dolomite and gray massive bioclastic limestone. Only a fraction of gray massive fine crystalline limestone, sparry calcarenite, and calcirudite are on top of the upper part. The Honghuayuan Formation is generally composed of light gray to gray medium-thick bedded or massive bioclastic limestone, reef limestone, and calcarenite with a few sandstones at the bottom. The δ18OPDB values of 18 samples are less than -11‰; in addition, the Pr/Pr* and Ce/Ce* ratios are greater and less than 1, respectively. These data reflect a sedimentary environment. The lower part of the Tongzi Formation might have been formed in an evaporite platform, which was then transformed into a restricted one, which featured a dry climate, a shallow water depth, and an insufficient amount of oxygen. By contrast, the upper part of the formation was deposited in an open platform, which featured a humid climate and relatively increased water depth and reducibility. During the sedimentary period of the Honghuayuan Formation, the water energy further increased, the climate became humid, the water depth increased, and the reducibility increased. Correspondingly, the sedimentary environment, which originally comprised littoral facies that slowly developed into an open platform and into a platform marginal bank, gradually evolved into a platform marginal reef.

Biogeochemical Surveys Using Poultry Components from Mangampeta Barite Area, Andhra Pradesh, India

The present work deals with the trace element interactions in excreta, feathers, and eggs of hens of backyard poultry of Mangampeta barite area, Kadapa District, Andhra Pradesh to determine its significance in biogeochemical surveys. For purpose of comparison, excreta, feathers and eggs from the birds of caged system of poultry in Tirupati, Andhra Pradesh are also collected. The excreta and eggs of hens of backyard poultry reflect the composition of their immediate geochemical environment while those of hens of caged system of poultry show their feed composition. Variations in trace element content are observed in poultry components on ash weight and dry weight basis. Organic matter plays an important role in the behavior and distribution of trace elements. The excreta of hens of backyard poultry can be utilized as a tool in biogeochemical orientation surveys as they reflect their surrounding geochemical environment. The biogeochemical investigations of all these biological samples are helpful in the preparation of multi-element atlases for the effective study of environmental geochemistry.

Trace element variation in olivine in the Skaergaard intrusion: petrologic implications

Olivine from the Layered Series (LS), Upper Border Series (UBS), and Marginal Border Series (MBS) of the Skaergaard intrusion was analyzed to examine trace element variations. In general, olivine from all three series shows similar trends in trace elements with differentiation. Ba, Cs, Rb, and Sr, acted as excluded trace elements and the transition elements, Co, Cr, Cu, Ni, Sc, Zn, and V, are included in Skaergaard olivine. Owing to the high DNi in olivine, Ni decreases with differentiation in both olivine and the calculated Skaergaard magma. The low concentration of Cr in olivine is attributable to early depletion of Cr by pyroxene crystallization. Decreases in the abundances of V and Co are related to the onset of magnetite crystallization and the separation of immiscible Co-rich sulphide. In general, calculated partition coefficients (Di) for Skaergaard olivine show similar trends in the LS, UBS, and MBS. Calculated Di’s for Sc, Cr, and Ga in olivine, progressively increase, and Di’s for Zr, Nb, Hf, Cs, Ta, Th, and U progressively decrease, with differentiation. The systematic variation in trace element contents of Skaergaard olivine during differentiation would appear to preclude the possibility of any significant injection of new magma into the chamber during differentiation. The Ni content in Skaergaard olivine systematically decreases with differentiation as would be expected if the intrusion remained a closed system. In fact, no abrupt increases are observed in the abundances of any of the transition metal in olivine during differentiation.

Variation in Trace Element Contents Among Chicken, Turkey, Duck, Goose, and Pigeon Eggs Analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS)

Despite substantial interest in the trace element content of eggs by poultry breeders, nutritionists, and environmental scientists, available data about trace elements levels in eggs are scarce. Trace element contents in yolk and albumen of chicken, turkey, duck, goose, and pigeon eggs were analyzed to establish a baseline dataset and assess differences among trace element content in avian species. We measured the selenium (Se), zinc (Zn), manganese (Mn), cobalt (Co), copper (Cu), molybdenum (Mo), vanadium (V), chromium (Cr), nickel (Ni), arsenic (As), cadmium (Cd), and thallium (Tl) contents in both yolk and albumen by inductively coupled plasma mass spectrometry. One hundred twenty eggs deriving from 24 birds of each species, reared in the same poultry farm in northern Greece, were used; bird feed was common and based on cereals and legumes and contained no added vitamins or microminerals. Trace element contents in yolks were far higher than those in albumen, except for V and Ni. In yolks, the highest content for Se, Mo, and Tl were in pigeon eggs, for Zn, Mn, Cu, and Cr in turkey eggs, and for Co and Ni in goose eggs. In albumen, Se was highest in duck eggs, while Zn, Mn, and Co in pigeon ones. It is concluded that there is a substantial, up to threefold, variation for trace element contents in eggs among different domestic avian species offered the same feed.

Trace elements in supergene phosphorites

Supergene phosphorites were analyzed for Sr, Ba, Zn, Cd, Sc, Cr, Ag, and V, i.e., elements incorporated in carbonate-apatite by isomorphic substitution. The phosphorites were subdivided into four groups: (1) phosphorites related to the weathering of sedimentary rocks, (2) phosphorites related to the weathering of endogenous rocks, (3) lacustrine coprolite phosphorites, and (4) phosphorites of ocean islands. In all the phosphorites groups, Sr, Zn, and Ba were the most abundant of the trace elements, whereas Cd, Ag, and Sc showed the lowest concentrations. Variations in trace element contents between supergene phosphorites of different genetic groups or within a single group can be explained by the different compositions of weathered rocks and geochemical environments of supergene phosphorite formation. At the same time, the contents of some trace elements are correlated with the structural type of phosphorite. In particular, phosphorite crusts or only their outer parts show elevated contents of chalcophile elements (Cd, Zn, and Ag), whereas massive phosphorites and inner parts of crusts are often enriched in such lithophile elements as Sc, V, and Cr. It was found that Cd, Zn, Ag, Sr, and Ba are positively correlated with CO2 but show negligible correlations with other constituents of carbonate-apatite.

Direct major- and trace-element analyses of rock varnish by high resolution laser ablation inductively-coupled plasma mass spectrometry (LA-ICPMS)

Laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) was used to determine major and trace element concentrations in rock varnish samples from the Lahontan Range, near Fallon, NV and from a remote wilderness area near the San Juan River, in southeastern Utah. The data indicate that rapid LA-ICPMS analyses provide ample analytical resolution for semi-quantitative compositional determinations of both trace and major elements in the varnish despite the presence of a rock substrate component in most analyses. The overall major element contents of rock varnish from the two localities are grossly similar to rock varnish from other locations analyzed by solution ICPMS, electron microprobe, and energy dispersive scanning electron microscopy (SEM). Differences between microprobe and LA-ICPMS analyses may stem from different sampling scales and different degrees of substrate involvement. It was possible to detect significant variations in trace element contents in the rock varnish samples. The Lahontan Range is situated within a belt of W mineralization, and varnish from that locality contained significantly higher W and Mo contents than varnish from localities outside the W belt. Lead, Tl, Bi, Cd and As contents of varnish-coated pebbles from near the San Juan River in southeastern Utah, varied by an order of magnitude as a function of the position of the sampling site on the pebble. Elevated heavy element contents on the skyward-facing varnish surfaces indicate that heavy elements may be preferentially scavenged at the locations most likely to receive direct inputs of atmospherically-deposited airborne particulates. The source of metal-rich airborne particulates, in this case, is probably any one of several large coal-fired power plants in the Four Corners region, proximal to the San Juan study area. These patterns indicate that rock varnish chemistry is influenced by atmospherically-derived fluxes of both dissolved and particulate constituents, and that rock varnish can be used as a passive environmental indicator for a wide variety of elements, in much the same manner as moss and lichens.

Sedimentology and trace element geochemistry of shallow-marine carbonates: an approach to paleoenvironmental analysis along the Pagny-sur-Meuse Section (Upper Jurassic, France)

The Middle Oxfordian formations of the eastern edge of the Paris Basin (France) contain mostly shallow-marine carbonate sediments. A detailed sedimentological study of the Pagny-sur-Meuse section reveals five major environments that make up a depositional profile succession grading from tidal-flat to distal lagoon/oolithic shoal. Stratigraphic cycles were established and illustrate variations of the A/S ratio (accommodation rate/sedimentation rate) and hence variations of accommodation space. Geochemical analyses (Sr, Mg, Fe, and Mn) have been conducted along a part of the section. Statistic analysis of the geochemical data (box diagrams and principal component analysis, PCA) are used to investigate similarities between the variations of trace element contents and depositional environments. An analysis of variance (ANOVA) is used to test whether the amounts of trace elements are related to the depositional environments. The relationship is highly significant for Sr, Fe, and Mn. A number of a posteriori tests are performed with this ANOVA to compare the geochemical data for each environment. Tidal-flats and distal lagoon/oolithic shoal transition are the most significantly discriminated environments. Differences among the lagoonal environments are less obvious. Despite (1) an open diagenetic system that explains the low Sr values and (2) the possible influence of clays on Fe–Mn contents in the upper part of the section, some of the variations in Sr and Fe–Mn seem to reflect changes in depositional environment. A number of hypotheses are proposed about the relations between trace elements and paleoenvironmental parameter records: Sr contents may illustrate variations of paleosalinity in depositional environments, whereas Fe and Mn contents seem to record variations of specific low detrital inputs coming from isolated islands submitted to pedogenesis. Low Sr content coupled with relatively high Fe and Mn contents is indicative of low salinity environment near subaerially exposed islands, located in the proximal part of a reconstructed theoretical depositional profile. Conversely, high Sr content coupled with relatively low Fe and Mn contents reflect a more open marine environment in the distal part of the same profile. Such analysis based on trace element geochemistry does not constitute a model but it shows that Sr, Fe, and Mn can partially record indications about paleoenvironmental conditions in shallow-marine carbonates.

Magmatic-to-hydrothermal crystallization in the W–Sn mineralized Mole Granite (NSW, Australia): Part II: Evolving zircon and thorite trace element chemistry

The Sn–W mineralized Mole Granite in Eastern Australia hosts zircon populations that crystallized at several stages during a protracted magmatic to hydrothermal evolution. Thirty-four elements have been quantified by laser-ablation inductively-coupled-plasma mass-spectrometric microanalysis with the aim of relating the chemistry of zircon to its growth environment. Trace element contents are highly variable for all textural occurrences. Zircon inclusions in earliest quartz phenocryst suggest that zircon was a liquidus phase that crystallized probably deep in the crust. Trace element contents are conspicuously high, showing only a slight positive Ce anomaly but a pronounced negative Eu-anomaly. Successive crystallization stages of magmatic zircon are characterized by progressive depletion in trace element contents, notably the rare earth elements, with an increasingly important positive Ce-anomaly. This evolution reflects saturation of REE accepting minerals such as monazite, thorite, xenotime and possibly apatite and is affected little by the exsolution of a magmatic–hydrothermal fluid. Zircon that is interpreted to have precipitated from aqueous fluids in Sn–W-bearing quartz veins shows REE patterns indistinguishable from those of late magmatic zircon. When combined with experimental evidence on the fluid–melt partitioning of REE, it indicates that the REE distribution coefficients for zircon/melt and zircon/fluid are largely comparable. The second example of hydrothermal zircon crystallized some 2 My after the host granite. These crystals reveal an intragranular zonation of increasing trace element concentrations from core to rim. Therefore, REE abundances and patterns alone are not conclusive indicators of the geological environment in which zircon crystallized. Nevertheless, variations in trace element contents of zircon that relate to the chemistry of the melt or fluid from which zircon crystallized, as measured in cogenetic melt and fluid inclusions, are promising for future petrogenetic modeling. Lead and Cs are strongly incompatible in hydrothermal zircon, with estimated zircon–fluid distribution coefficients D ≤ 0.001, while Sn and Li are moderately incompatible, D Sn ∼ 0.6 and D Li ∼ 0.1, and Ce is compatible, D Ce ∼ 14. Moreover, hydrothermal zircon has a more pronounced negative Eu-anomaly and higher Ta/Nb and U/Th ratios than the magmatic zircons of the Mole Granite.

Spatial and Temporal Variations of Trace Element Contents in Xanthoria Parietina Thalli Collected in a Highly Industrialized Area in Northern France as an Element for a Future Epidemiological Study

This work was made in Dunkirk, which is located on the French coast, in the north, near Belgium and Great Britain. The study concerned the industrial and urban surroundings of Dunkirk and Dunkirk itself. Objectives of our study is (1) to monitor spatial patterns and temporal trends (1995–2003) of trace element (As, Cd, Hg, Ni, Pb, V, Zn) deposition and (2) to make a first evaluation of exposed population to highest metals concentrations. This work is the first step of future epidemiological investigation. In 1995, the high lead concentrations were due to industrial emissions and to traffic. Zinc and arsenic concentrations were also high and widespread in the entire studied zone, but higher near industrial area. Mercury concentrations were limited in the western part and clearly revealed the impact of waste incinerator. We did not find any significant difference between trace element contents in lichens between 1995 and 2003 except for mercury, which decreased. In 2003, the contamination by lead was more focused in the biggest metallurgical plant, which is now the predominant source for this element. The traffic impact decreased, but there was still lead remaining. For the other elements the highest concentrations were observed near the industrial zone. Highest contaminations concern 25–33% of the population, who live near industrial zone in districts where annual average incomes are the lowest. Those results confirm the needs for a further epidemiological study, which could take place in priority where population is the most exposed.

Trace elements evaluation of some medicinal herbs by instrumental neutron activation analysis

Abstract Instrumental neutron activation analysis has been used for the analysis of seven varieties of medicinal herbs generally used by the people of South Asian region. Twenty-one trace elements (essential, toxic and non-essential) were determined. This data should not only be helpful in establishing the base-line values in these medicinal herbs but also in correlating their role as therapeutic agents. A comparison of our data with literature values shows variation in trace element contents of same species of different origin which can be attributed to ecological and geographical variations to some extent; however an exact interpretation demands further extensive investigations.

The response of ostracod shell chemistry to seasonal change in a Mediterranean freshwater spring environment

We established the relationships between water chemistry changes in a pool fed by a permanent spring and seasonal variations in trace-element contents (Sr & Mg) in the shells of the ostracod species Herpetocypris intermedia, based on monthly collections of ostracod and water samples. The water chemistry of the investigated pool (Maiques, Valencia, Spain) was dominated by calcium and bicarbonate, and showed marked seasonal variation in alkalinity, Ca2+ content, Sr/Ca and Mg/Ca ratios. Although the variability in the water chemistry was relatively low (similar to 10% relative standard deviation over the entire period), the trace-clement contents: in the ostracod shells tracked the seasonal change in the water chemistry of Maiques pool. Moreover, due to the rapid renewal of H. intermedia population, this species is able to record in its shells the evolution of the water chemistry at a monthly time scale. Our results also showed that, in the Maiques pool system, ostracod Sr/Ca and Mg/Ca ratios increased with the decrease in water salinity. To our knowledge, this is the first geochemical study of ostracods dwelling in spring environments. The results of this study may be applied to paleohydrological reconstruction using ostracods preserved in sediments deposited around springs (i.e., travertine and tufa deposits).

Chemical diagenesis in fossil shells from Baja California, México studied using PIXE and mass spectrometry

In this work we present elemental composition determined by PIXE, and 13C and 18O stable isotope concentrations determined using mass spectrometry for recent and Late Miocene-Pliocene marine shells deposits in Baja California, México. Recent and fossil mollusk shells show large variations in trace element content along growth lines. Diagenesis in fossils mollusks has resulted in different degrees of depletion in Sr, 13C and 18O. An enrichment in Mn, Fe and Zn due to the diagenesis process was not clearly observed.

Trace elements (Zn, Cu, Cd) in fish from rearing ponds of Emilia-Romagna region (Italy)

Significant differences in Zn and Cu content were found between different organs. Zinc reaches its maximum, mean value (929 μg/g dry wt), in the kidney of the common carp and consistently has a high value (276–552 μg/g dry wt) in the ovary of all the species examined; Cu is at its maximum (21 μg/g dry wt) in the liver of goldfish. Zinc concentration in brain tissue is rather constant and is probably well regulated because of a functional role in this organ. Cadmium was only found in the liver and kidney, being approximately four times higher in the latter. Seasonal variations in trace element contents have been demonstrated in some organs of catfish; in the ovary, zinc concentrations could be linked with the reproductive cycle, while in the muscle with a growth cycle.

Trace element geochemistry of ilmenite megacrysts from the Monastery kimberlite, South Africa

Ilmenite megacrysts in the Monastery kimberlite occur both as discrete monomineralic crystals and intergrown with all the other phases of the Cr-poor megacryst suite (cpx, opx, garnet, Fe-rich olivine, phlogopite and zircon). The ilmenites show systematic variations in trace element content which are interpreted in terms of a fractional crystallization model. Covariation of major and trace elements in the ilmenites with respect to their Nb content defines smooth curves, with breaks in the trends corresponding to changes in the inferred cumulate assemblage. Nb apparently behaved as an incompatible element in the megacryst magma throughout its crystallization history, and the Nb content of ilmenite serves as a useful fractionation index. After the appearance of ilmenite, the crystallization sequence of the Monastery megacryst suit is ilmenite+cpx+garnet+opx, followed by ilmenite+phlogopite, then ilmenite+zircon±phlogopite and finally by ilmenite+zircon+olivine+phlogopite. The incompatible behaviour of Nb indicates that ilmenite was overall never a predominant phase in the cumulate assemblage. Elevated Cr contents in late-stage ilmenites cannot be explained by the simple fractional crystallization model, and may require another process such as magma mixing or magma reaction with wall rock. The parent megacryst magma must have been highly magnesian and enriched in incompatible trace elements and in this respect may have been similar to meimechite. The late differentiate of this magma cannot be kimberlite, but must be undersaturated and high in iron, potassium, titanium and incompatible elements.