Mean Concentrations Of Trace Elements Research Articles

Physicochemical composition, minerals, and pesticide residues in organic grape juices

Demand for organic products is intensified in many countries each year. Following this trend, Brazil produces increasing volumes of organic grape juice. In this way, a survey of organic grape juices made from grapes produced according to this system was carried out where physicochemical composition, minerals, trace elements, and pesticide residues were determined. Variables related to grape juice composition were performed by physicochemical procedures; minerals and trace elements, by inductively plasma optical emission spectrometry; pesticide residues, by liquid chromatography-mass spectrometry. Main results show that the physicochemical composition of organic grape juices was in general in accordance to the Brazilian legislation. The mean concentrations of trace elements were very low, varying from 0.002 (Cd) to 0.970 (Ba) mg L–1. Pesticide residues were not detected in any sample analyzed (MRL= 10 µg L–1). These results show that the Serra Gaúcha viticultural region present conditions to produce organic grape juices, despite the adverse climate factors that occurs in some years. Nevertheless, these products should be made with grape varieties, such as the labrusca ones, less susceptibles to the main grapevine pathogens.

Interspecific Differences in Egg Production Affect Egg Trace Element Concentrations after a Coal Fly Ash Spill

In oviparous vertebrates, trace elements transfer from mother to offspring during egg production. For animals that produce eggs slowly, like turtles, the trace element concentration of each egg reflects an integration of dietary and stored accumulation over the duration of vitellogenesis. Because turtles also produce eggs synchronously, all eggs within a clutch should exhibit uniform trace element concentrations. In contrast, for animals that produce eggs in sequence and primarily from current dietary resources, like many birds, the trace element concentrations of eggs should be less uniform within a clutch, and likely reflect short-term changes in dietary exposure. We tested the hypothesis that stinkpot turtle (Sternotherus odoratus) clutches exhibit lower variability and higher repeatability in barium, selenium, strontium, and thallium concentrations than those of tree swallows (Tachycineta bicolor) from a site impacted by a recent coal ash spill. All four trace elements exhibited significantly lower variability and significantly higher repeatability in stinkpot clutches than in swallow clutches. Mean trace element concentrations of stinkpot eggs were also significantly higher than those of swallow eggs although both species feed primarily on aquatic invertebrates. Variability in swallow egg trace element concentrations was partially due to significant laying order effects. Our results support the hypothesis that interspecific variation in the source of resources and in the synchronicity and rate of egg production can lead to interspecific differences in the variability of egg trace element concentrations.

Toxic Element Concentrations in the Bottlenose (Tursiops truncatus), Striped (Stenella coeruleoalba) and Risso’s (Grampus griseus) Dolphins Stranded in Eastern Adriatic Sea

Concentrations of cadmium (Cd), arsenic (As), mercury (Hg) and lead (Pb) were measured in muscle, liver and kidney of three cetacean species, the bottlenose (Tursiops truncatus), striped (Stenella coeruleoalba) and Risso's (Grampus griseus) dolphins from the Croatian waters of the Adriatic Sea. In all three dolphin species Cd levels decreased in tissues in the order: kidney>liver>muscle, while As and Pb decreased in the order: liver>kidney>muscle for striped and Risso's dolphins, but with the order reversed for liver and kidney in the bottlenose dolphin for Pb. Levels of Hg consistently followed the order: liver>muscle>kidney, with mean concentrations in the liver being 11-34times higher than in the other tissues. The highest mean concentrations of trace elements were measured in Risso's dolphins at 14.9μg/g wet weight, for Cd in the kidney, and concentrations in the liver of 2.41, 1,115 and 0.63μg/g for As, Hg and Pb, respectively. Statistically significant differences between the three dolphin species were determined for Cd, Hg and Pb in liver tissues, for As in muscle and for Cd in kidney. Significant correlations of metals between tissues were determined in all three species. The results presented give an indication of the environmental condition with regard to the content of toxic metals along the eastern coast of the Adriatic Sea.

Trace Element Concentrations in Some Traditional Diets Consumed in Selected Parts of Eastern Province of Kenya

Dietary quality is vital in maintaining sound nutritional status. The ecological conditions thus influence the type of diets and their nutritional quality. The purpose of this study was to determine the trace element/mineral content of some of the commonly consumed diets in Machakos, Kitui, Makueni and Mwingi districts. Decorticated maize, beans and finger millet flour samples were purchased from the local markets. For each category, a total of ten samples were collected from each district. The samples were put in plastic bags, sealed and transported to the laboratory in the Institute of Nuclear Science & Technology, University of Nairobi for preparation and analysis. The cooking of the samples was carried out according to local traditional methods. In the decorticated samples, mean copper concentrations were observed to be below 20 μg·g-1; mean zinc concentrations ranged from 34 to 63 μg·g-1 and mean manganese concentrations were in a similar range of 34 to 78 μg·g-1. The mean iron concentrations were significantly high with a range of 161 μg·g-1 to 287 μg·g-1. A similar trend was observed in the beans where the mean copper concentrations varied from 11 to 33 μg·g-1, mean zinc concentrations ranged from a low value of 24 μg·g-1 to a high value of 35 μg·g-1, mean manganese concentrations varied from 33 μg·g-1 to 98 μg·g-1 and the mean iron concentrations ranged from 227 μg·g-1 to 647 μg·g-1. The cooked Muthokoi samples from Machakos district had relatively high mean trace element concentrations: manganese—109 μg·g-1; iron—280 μg·g-1; copper—19 μg·g-1; and zinc—41 μg·g-1. The only exception was mean iron concentrations which were extremely high in samples from Mwingi District where the concentrations varied from 73 μg·g-1 to 1597 μg·g-1. In finger millet flour, the mean manganese concentrations varied from 95 to 290 μg·g-1, whereas the mean iron concentrations ranged from 127 μg·g-1 to 259 μg·g-1. In contrast, the mean copper and zinc concentrations were low in comparison to the manganese and iron concentrations. As a whole, the mean copper concentrations in the diets are significantly low compared to the other three trace elements. However, the total content is not necessarily a reflection of the amount assimilated in the body. Finger millet was found to be an excellent source of manganese and iron whereas beans were observed to be good sources of iron. All the food crops were observed to poor sources of copper.

Inorganic arsenic and trace elements in Ghanaian grain staples

A total of 549 samples of rice, maize, wheat, sorghum and millet were obtained from markets in Ghana, the EU, US and Asia. Analysis of the samples, originating from 21 countries in 5 continents, helped to establish global mean trace element concentrations in grains; thus placing the Ghanaian data within a global context. Ghanaian rice was generally low in potentially toxic elements, but high in essential nutrient elements. Arsenic concentrations in rice from US (0.22 mg/kg) and Thailand (0.15 mg/kg) were higher than in Ghanaian rice (0.11 mg/kg). Percentage inorganic arsenic content of the latter (83%) was, however, higher than for US (42%) and Thai rice (67%). Total arsenic concentration in Ghanaian maize, sorghum and millet samples (0.01 mg/kg) was an order of magnitude lower than in Ghanaian rice, indicating that a shift from rice-centric to multigrain diets could help reduce health risks posed by dietary exposure to inorganic As.

Bioaccumulation of trace elements in different tissues of three commonly available fish species regarding their gender, gonadosomatic index, and condition factor in a wetland ecosystem

In the present research, accumulation of Cd, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn were determined in sediments and fillet, liver, kidney, gonads, and gills of three commonly fish species in the largest wetland ecosystem that is located in southwest of Iran; Shadegan wetland. Shadegan is one of the most important wetland that posses various fauna and flora but suffers inputs from agricultural and industrial activities. So, sediment samples and fish species including Barbus grypus, Barbus sharpeyi, and Cyprinus carpio were collected during winter 2009. Results showed that mean concentrations of trace elements (except Ni and Co) were high in liver and gills of B. grypus. Also trace elements had the most accumulation in liver of B. sharpeyi except for Cd (0.26 mg kg(- 1) d.w.) and Mn (13.45 mg kg(- 1) d.w.) that were high in gills. Beside, kidney is determined as target tissue for Ni and V in B. grypus and for Pb in C. carpio, due to their high concentration. Zn levels in all tissues of C. carpio showed the highest concentrations in comparison to other fish species. Generally, accumulations of most of the studied elements in B. grypus and B. sharpeyi were higher in females than in males, while in fillet and gonads of C. carpio, this trend was inverted. Bioaccumulation factors (BAFs) were determined for different tissues of fish species with respect to elemental concentrations in sediment. BAFs results indicated that Zn, Pb, and Cu have higher BAF than other elements. Also this investigation demonstrated that trace elements have different affinities with condition factor of studied fish species. Gonadosomatic index (GSI) and Pb showed positive correlation together in both B. sharpeyi and B. grypus, respectively, in females and males. Moreover, females of C. carpio showed significantly positive relation of GSI and all studied elements.

Geochemistry of highly acidic mine water following disposal into a natural lake with carbonate bedrock

Abstract Acid mine drainage (AMD) from the Zn–Pb(–Ag–Bi–Cu) deposit of Cerro de Pasco (Central Peru) and waste water from a Cu-extraction plant has been discharged since 1981 into Lake Yanamate, a natural lake with carbonate bedrock. The lake has developed a highly acidic pH of ∼1. Mean lake water chemistry was characterized by 16,775 mg/L acidity as CaCO3, 4330 mg/L Fe and 29,250 mg/L SO4. Mean trace element concentrations were 86.8 mg/L Cu, 493 mg/L Zn, 2.9 mg/L Pb and 48 mg/L As, which did not differ greatly from the discharged AMD. Most elements showed increasing concentrations from the surface to the lake bottom at a maximal depth of 41 m (e.g. from 3581 to 5433 mg/L Fe and 25,609 to 35,959 mg/L SO4). The variations in the H and O isotope compositions and the element concentrations within the upper 10 m of the water column suggest mixing with recently discharged AMD, shallow groundwater and precipitation waters. Below 15 m a stagnant zone had developed. Gypsum (saturation index, SI ∼ 0.25) and anglesite (SI ∼ 0.1) were in equilibrium with lake water. Jarosite was oversaturated (SI ∼ 1.7) in the upper part of the water column, resulting in downward settling and re-dissolution in the lower part of the water column (SI ∼ −0.7). Accordingly, jarosite was only found in sediments from less than 7 m water depth. At the lake bottom, a layer of gel-like material (∼90 wt.% water) of pH ∼1 with a total organic C content of up to 4.40 wet wt.% originated from the kerosene discharge of the Cu-extraction plant and had contaminant element concentrations similar to the lake water. Below the organic layer followed a layer of gypsum with pH 1.5, which overlaid the dissolving carbonate sediments of pH 5.3–7. In these two layers the contaminant elements were enriched compared to lake water in the sequence As

Air quality assessment in urban areas of Gipuzkoa (Spain)

Objectives To evaluate the air quality to which a population of 90,000 inhabitants in the province of Gipuzkoa (Basque Country, Spain) is exposed. The population resides in a periurban environment, where industrial activity (11 iron and steel foundries) is scattered among residential areas. Methods Throughout 2006 and 2007, levels of particulate matter less than 2.5 mm in diameter (PM 2.5) were quantified and levels of trace elements in PM 2.5 fraction [cadmium (Cd), arsenic (As), manganese (Mn), copper (Cu), chromium (Cr), nickel (Ni), iron (Fe), lead (Pb), mercury (Hg) and zinc (Zn)] were analyzed. The samples were gathered in seven sampling sites using three high-volume Digitel DAH 80 samplers. Annual and seasonal variability were evaluated for the various contaminants in each valley and PM 10 and PM 2.5 samples were also gathered at the same site for a month, with the goal of analyzing the composition of trace elements in each particle size. Finally, the results were compared with those obtained from the same study area by the Basque Government Air Quality Network equipment. Results The observed PM 2.5 concentrations (12.2–28.9 μg/m 3) were similar to those described in urban environments in large European cities, while mean trace element concentrations were significantly higher. The Mn levels observed in all three valleys indicated the influence of the steel and metal industries on air quality. Conclusion The finding that levels of particulate matter and trace elements in the study area were similar to or higher than those found in metropolitan areas has implications for the evaluation of health risks in populations far from large population centers.

Trace elements in urban and suburban rainfall, Mersin, Northeastern Mediterranean

Spatial/temporal variabilities of rainwater constituents are examined based on soluble/insoluble trace elements, pH and electrical conductivity measurements in rainfall sampled during December 2003–May 2005 at two urban and two suburban sites in Mersin, an industrialized city of 850,000 inhabitants on the southern coast of Turkey. In the analyses, backward air mass trajectories for rainy days were used in addition to factor analyses, enrichment factors, phase distributions and correlations between trace elements. The pH varied from 4.8 to 8.5 with an average value of 6.2, reflecting a mainly alkaline regime. Mean concentrations of trace elements collected from urban and suburban sites are spatially variable. Based on the overall data, total concentrations of trace elements were ordered as Ca > Na > Fe > Al > Mg > K > Zn > Mn > Sr > Pb > Ni > Cr > Ba > Cu > Co > Cd. Mainly terrigeneous (Ca, Fe, Al) and, to a lesser extent, sea salt particles (Na, Mg) were shown to be the major source of trace elements. Excluding major cations, the solubilities of trace elements were found to be ordered as Sr > Zn > Ba > Mn > Cu > Ni > Cr > Fe > Al, confirming the lower solubility of crustal elements. Cd, Co and Pb were excluded from the above evaluation because of the low numbers of soluble samples allowing quantitative measurements. The solubilities of Al, Fe, Mn and particularly of Ni were found to be considerably lower than those reported for various sites around the world, most likely due to the effect of pH. During the entire sampling period, a total of 28 dust transport episodes associated with 31 red rain events were identified. Extremely high mean concentration ratios of Al (8.2), Fe (14.4) and Mn (13.1) were observed in red rain, compared to normal rain. The degree of this enhancement displayed a decrease from crustal to anthropogenic origin elements and the lowest enhancements were found for anthropogenic origin elements of Zn and Cd (both having a ratio of 1.1). Aerosol dust was found to be the main source of almost all analyzed elements in Mersin precipitation, regardless that they are crustal or anthropic derived elements. The magnitude of crustal source contribution to trace element budget of precipitation was at its highest levels for crustal originated elements, most probably due to much higher scavenging ratios of crustal elements compared to anthropogenic ones.

Paleozoic plume-lithospheric processes in northeastern Fennoscandia: Evaluation of the composition of the parental mantle melts and magma generation conditions

The paper reports quantitative evaluations of the modal and chemical composition of the mantle whose Paleozoic activation gave rise to the Kola alkaline province in the northeastern Baltic Shield. The volume of alkaline magmatism within the province and the volume of the mantle melts that were generated in the course of the Paleozoic activation cycle were evaluated by three-dimensional density modeling on the basis of gravimetric data. Our studies involved, along with the sampling of alkaline magmatic rocks in the region, the examination of the deep (to a depth of 22.5 km) structure of all alkaline intrusions in the province and the development of their three-dimensional density models. Concentrations of trace elements were precisely analyzed by the ICP-MS technique, and these data were used in order to calculate the weighted mean concentrations of trace elements in rocks of the province, to simulate the melting of mantle sources, and to evaluate the geodynamic sequences of these mantle processes. Our simulations indicate that the total volume of the Paleozoic mantle melts in the northeastern part of the Baltic Shield amounted to 15000 ± 2700 km3. The calculated composition of the partial melts that could be produced by the mantle of average composition shows the necessity for the significant introduction of certain elements into the mantle source. It is demonstrated that primitive melts in the Kola province were highly probably derived at low degrees of melting of the source (0.3–0.5%), whose composition corresponded to phlogopite-bearing (±amphibole) garnet lherzolite under the conditions of the mantle garnet depth facies. The calculated degree of enrichment of this sources was three times higher than the average concentrations of incompatible elements in the primitive mantle. It is demonstrated that magma generating processes affected much of the lithosphere beneath northeastern Fennoscandia and reached a depth of 120 km, i.e., the depth of the mantle facies of garnet lherzolite. The area of this region corresponds to the area of regional Paleozoic magmatism, and its depth correlates with the estimated P-T conditions under which the mantle xenoliths found in regional diatremes were formed.

Relationship between hair elements and severity of atrioventricular block in horses

The aim of this study was to investigate the relationships between the mean concentrations of trace elements and the severity of the second-degree atrioventricular (AV) block in the mane hair of horses. Electrocardiographs of horses were continually recorded for 6 h using a holter cardiac monitor to determine dropped ventricular beats (DVBs) which can be used as an indicator of the severity of the AV block. Mane hair Ca, Cu, Mg, and Zn concentrations were measured by the particle-induced X-ray emission method. The Zn/Cu ratio and Ca concentration in mane hair were significantly and positively correlated with the hourly DVBs in horse with a second-degree AV block (p<0.01, r2=0.485; p<0.05, r2=0.351, respectively). Proposed diagnostic cutoff points for hair Ca concentration and Zn/Cu ratio based on receiver operating characteristics curves analysis in detecting second-degree AV block were set at 1536 microg/g and 26.0, respectively. Those results with horse hair suggest that the evaluation of the Ca, Cu, Mg, and Zn status in mane hair by this method is strongly related to the severity of second-degree AV block and might predict the susceptibility of an individual much before the development of the symptom.

Interannual patterns of variation in concentrations of trace elements in arms of Octopus vulgaris

Concentrations of essential (copper, iron, manganese, selenium, and zinc) and non-essential (arsenic, cadmium, mercury, and lead) trace elements were measured in arms of Octopus vulgaris. The cephalopods were sampled from commercial fishery landings at two sites on the Portuguese coast in spring 2002 and 2003. Mercury was determined using an Advanced Mercury Analyser Spectrophotometer (AMAS) and other trace elements were measured using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Since high levels of arsenic were detected, identification of the forms present was carried out using high performance liquid chromatography (HPLC) followed by ICP-MS. Mean concentrations of trace elements analysed were in the following order: As > Zn > Fe > Cu ≫ Cd > Pb > Se > Mn ≫ Hg. The results of speciation of arsenic demonstrate that virtually all arsenic was in the arsenobetaine form, which is the less toxic form. The concentrations of several trace elements were generally high in samples from Viana in 2002. Cadmium concentrations were above the legal limit for human consumption in samples from Viana in 2002 and two of these animals also had lead concentrations that exceeded legal limits. Mercury appeared in all samples but levels were within legally defined safe limits. No relationship was detected between trace element concentrations and size or maturity of octopus.

Influence of Black Shales on Soils and Edible Plants in the Ankang Area, Shaanxi Province, P. R. of China

The Ankang black shales in P. R. of China provides an important example of natural geological materials containing toxic elements. This paper presents the results of environmental geochemical research on black shales, soils, waters and edible plants in the Ankang area, Shaanxi Province, P. R. of China. The study area lies in the northern margin of the Yangtze Platform; there are black shales which contains black shale, carbonaceous rocks and coal in the Cambrian Donghe Formation throughout the area. Mean trace element concentrations of the coal were high. Soils derived from these rocks tend to reflect their extreme geochemical composition. Chemical analysis of common plant species in the Ankang area showed a heterogeneous distribution of Se, Mo, and V within a single and among plant species. Selenium was more concentrated in radish than in legumes, and in potato more than in green vegetable. High V concentrations were found in two kinds of Chinese tea. Legume had more Mo in the seed than potato, although Mo concentrations in radish vary. Higher concentrations of Se and Mo are present in the leaf of radish.

Monitoring the content and intake of trace elements from food in Denmark

The content of cadmium, lead, nickel, mercury and selenium in 83 foods was monitored from 1993 to 1997. In comparison with similar results from 1988 to 1992, a general decrease in lead levels had occurred, whereas the contents of cadmium, nickel, mercury and selenium were stable or declined only slightly. The distribution in dietary intake of the five trace elements was estimated by combining the mean trace element concentrations with food consumption data from 1837 Danes aged 15–80 years. The lead intake for 1993–97 showed a decrease in comparison with similar estimates from the previous monitoring cycles: 1983–87 and 1988–92. The intake of cadmium and mercury decreased to a lesser extent, whereas the intake of selenium and nickel remained unchanged in the same period. The dietary intake of trace elements was compared with the provisional tolerable weekly intake (PTWI). The 95th percentile of the distribution in cadmium intake amounts to 34% of PTWI, which is relatively high, and therefore calls for a more detailed future risk assessment. The intakes of lead and mercury were 11% of PTWI and, like the intake of nickel, did not cause any health concern in the adult population. The Danes ingest close to 100% of the Nordic Nutrition Recommendation for selenium at 50 μg day-1, and no individuals had an intake less than the lower limit of 20 μg day-1.

Trace Elements in a Pliocene-Pleistocene Lignite Profile from the Afsin-Elbistan Field, Eastern Turkey

We present the results of proximate and ultimate analyses, mineralogical determination, and trace element analysis of a lignite profile from the Afsin-Elbistan field (eastern Turkey). The lignite, which developed during the Pliocene-Pleistocene transition under freshwater lacustrine conditions, contains white gastropod (Planorbidae) shells composed of calcite and a little aragonite. Other identifiable mineral constituents, analyzed by X-ray powder diffraction, include quartz, pyrite, clay minerals, and rare feldspars. Petrographical studies demonstrate the immature nature of these lignites and very low degree of compaction during diagenesis. The mean concentrations of trace elements in the lignite, determined by inductively coupled plasma mass spectrometry (ICP-MS), show relative enrichment in Mo (avg. 20 ppm), W (avg. 15 ppm) and U (avg. 25 ppm) when compared to the global range for most coals, while the others (Ti, P, Sc, Be, Mn, Co, Cu, Zn, Ga, As, Rb, Sr, Zr, Nb, Cs, Ba, Y, Ta, T , Pb, Bi, Th, La, Ce, Pr N , Sm, Eu, Gd, Tb, Dy, Ho Er, Yb, Lu) fall within their global ranges. Many of the trace elements show a good correlation with the ash yield, implying an inorganic affinity. However, Mo and Sr show a negative correlation with the ash yields and are thought to be organically associated. A lack of correlation of U with either the ash yield or the total sulfur content, together with its relative enrichment, suggests secondary mobility of this element.

Survey of trace elements in lake waters of Finnish Lapland using the ICP-MS technique

Water samples for trace element analyses (Cd, Pb, As, Ni, Cu, Cr, Zn, Al) were collected from small Finnish headwater lakes in 1992 in connection with the national monitoring program on, long-range transboundary air pollution (LRTAP) and surface water acidification. The lakes were situated all over the country, mainly in acid-sensitive upland areas. Data from this survey are compared with data from earlier surveys and the differences between northern Finland and other parts of the country are highlighted. Mean trace element concentrations were significantly lower for Cd, As, Zn and Ni in lakes in Lapland, compared with similar lakes in central and southern Finland, and reflected the pattern of atmospheric deposition. Chromium, with lowest concentrations in the south, showed similarities to the recent atmospheric load. No clear differences between areas were observed in concentrations of Pb and Cu. Concentration levels of trace elements in lakes in Lapland were similar to those in northern Sweden and close to the proposed background values. Element concentrations in Lapland correlated with lakewater acidity (Cd, Zn, As P < 0.001) and with the concentration of total organic carbon (TOC) (CrP < 0.001, Ni P < 0.01).

Compositional gradients in large reservoirs of silicic magma as evidenced by ignimbrites versus Taylor Creek Rhyolite lava domes

The Taylor Creek Rhyolite of southwest New Mexico consists of 20 lava domes and flows that were emplaced during a period of a few thousand years or less in late Oligocene time. Including genetically associated pyroclastic deposits, which are about as voluminous as the lava domes and flows, the Taylor Creek Rhyolite represents roughly 100 km3 of magma erupted from vents distributed throughout an area of several hundred square kilometers. Major-element composition is metaluminous to weakly peraluminous high-silica rhyolite and is nearly constant throughout the lava field. The magma reservoir for the Taylor Creek Rhyolite was vertically zoned in trace elements, 87Sr/86Sr, and phenocryst abundance and size. Mean trace-element concentrations, ranges in concentrations, and element-pair correlations are similar to many subalkaline silicic ignimbrites. However, the polarity of the zonation was opposite that in reservoirs for ignimbrites, for most constituents. For example, compared to the Bishop Tuff, only 87Sr/86Sr and Sc increased upward in both reservoirs. Quite likely, a dominant but nonerupted volume of the magma reservoir for the Taylor Creek Rhyolite was zoned like that for the Bishop Tuff, whereas an erupted, few-hundred-meter-thick cap on the magma body was variably contaminated by roof rocks whose contribution to this part of the magma system moderated relatively extreme trace-element concentrations of uncontaminated Taylor Creek Rhyolite but did not change the sense of correlation for most element pairs. The contaminant probably was a Precambrian rock of broadly granitic composition and with very high 87Sr/86Sr. Although examples apparently are not yet reported in the literature, evidence for a similar thin contaminated cap on reservoirs for large-volume silicic ignimbrites may exist in the bottom few meters of ignimbrites or perhaps only in the pumice fallout that normally immediately precedes ignimbrite emplacement. 87Sr/86Sr in sanidine phenocrysts of the Taylor Creek Rhyolite is higher than that of their host whole rocks. Covariation of this isotope ratio with sanidine abundance and size indicates positive correlations for all three features with decreasing distance to the roof of the magma reservoir. The sanidine probably is more radiogenic than host whole rock because growing phenocrysts partly incorporated Sr from the first partial melt of roof rocks, which contained the highly radiogenic Sr of Precambrian biotite ± hornblende, whereas diffusion was too slow for sanidine to incorporate much of the Sr from subsequently produced less radiogenic partial melt of roof rocks, before eruption quenched the magma system. Disequilibrium between feldspar phenocrysts and host groundmass is fairly common for ignimbrites, and a process of contamination similar to that for the Taylor Creek Rhyolite may help explain some of these situations.

Chemical studies of h chondrites: III. Regolith evolution of the fayetteville chondrite parent

Data for Ag, Au, Bi, Cd, Co, Cs, Ga, In, Rb, Sb, Se, Te, Tl, and Zn in consortium samples of solar-gas- and track-rich dark matrix, and dark and light clasts in the Fayetteville H chondrite regolith breccia were determined by radiochemical neutron activation analysis. The matrix proved chemically homogeneous at a level never before observed in an ordinary chondrite. Most dark clasts had similar mean trace element concentrations as matrix but were compositionally much more heterogeneous. Two clasts were unusual, one having apparently formed from impact-melted soil, the other representing a mixture of 90% matrix-10% C2M chondrite. The single light clast proved compositionally similar to H4–6 chondrite falls except for its higher contents of labile Bi, Cd, In, and Tl. Relative to matrix, all other samples seemed Cs-deficient. Other H chondrite regolith breccias studied in the past had shown peculiar Cs and/or Rb contents so that these alkalis seem diagnostic of such breccias. Dark portions of such breccias apparently represent compacted regolith soil produced by isochemical comminution of “normal” dark and light clasts. The dark clasts, in turn, likely represent primordial nebular condensate, although it is possible that they represent planetary “cold traps” that garnered labile elements generated elsewhere in the parent body.

Trace-element source and mobility during limestone burial diagenesis—an example from the Middle Jurassic of eastern England

Summary Two phases of burial calcite from the Lincolnshire Limestone (Bajocian) of central Lincolnshire have been analysed for their trace element (Fe, Mn, Mg, Sr) and strontium isotopic compositions. The earliest, non-ferroan, brightly luminescent phase has the following mean trace element concentrations: Fe- 919 ppm; Mn- 116 ppm: 3 1778 ppm; Sr- 327 ppm. The later, ferroan, dully luminescent phase has the following mean compositions: Fe- 3580 ppm; Mn- 225 ppm; Mg- 1400 ppm; Sr- 318 ppm. The strontium isotopic composition of the two phases is indistinguishable, with a mean 87 Sr/ 86 Sr ratio of 0.70820. This value is considerably more radiogenic than host Bajocian marine carbonate ( 87 Sr/ 86 Sr = 0.70725). The Fe and Mn of the burial calcites were sourced by iron and manganese oxyhydroxides associated with shales bounding (and internal to) the Lincolnshire Limestone. The relatively shallow maximum burial depths (550 m) and low temperatures (maximum of 42°C) attained by the formation in the area of study preclude major clay or sandstone diagenetic transformations as potential sources for Fe and Mn. These trace elements moved into the Limestone in solution via compaction driven cross-formational flow from bounding shale aquicludes. The Sr and Mg trace element components of the burial cements were derived from: (i) remobilized Bajocian marine carbonate, and (ii) remobilized Carboniferous marine carbonate. These sources satisfy the requirements of a linear Sr versus Mg relationship observed for the burial cements, that is, a constant Sr/Mg ratio with time, but highly variable absolute Sr and Mg contents. These sources also satisfy the near constant 87 Sr/ 86 Sr composition of the burial calcites. The burial hydrology required by the trace element budget above is a convective flow system with cross-formational elements as normal bleeder faults connecting the Carboniferous Limestone and the Lincolnshire Limestone. Additional compaction-driven flow occurred from bounding shale formations (chiefly the underlying Grantham Formation and to a lesser extent the Upper Estuarine ‘Series’) to the Lincolnshire Limestone. Up-dip flow within the fully confined Limestone provides an enformational limb to the convective system.

Trace metal distributions in Saint John Harbour sediments

The concentration and areal distribution of selected trace metals (Cu, Zn, Pb, Cd, Mo, Ni, Mn and Hg) in surficial sediments of Saint John Harbour, New Brunswick, Canada, were studied to determine the extent of anthropogenic input and to estimate the effects of dumping dredged material in the outer harbour. Hg and Cd are of especial concern, since the disposal of dredge material containing these two elements is regulated under the Ocean Dumping Control Act. The concentrations of all metals are low: Cu 16, Zn 53, Pb 24, Cd 0.16, Mo 3, Ni 16, Mn 296 and Hg 0.04 μg g −1. Hg and Cd levels in sediments are well below the permissible limits of 0.75 and 0.6 μg g −1, respectively, set by the Ocean Dumping Control Act. The mean concentrations of trace elements are similar to the low mean values in the unpolluted Bay of Fundy. There is an overall decline in concentrations of metals in the sediments from the inner to the outer harbour. Comparison of the metal levels in the sediments from different areas within the harbour indicate that there is a detectable anthropogenic input in the Courtenay Bay area. Trace metal levels at the dumpsite are significantly lower than in the Courtenay Bay area, where the bulk of the dredged material originates.