Multi-isotopic composition of brown crab (Cancer pagurus) and seafloor sediment from a mine tailing sea disposal impacted fjord ecosystem

Sea disposal of mine tailings in fjord ecosystems is an important coastal management issue in Norway and occurs at the land-sea interface. Here we studied accumulation of heavy metals in brown crab (Cancer pagurus) and seafloor sediment from Jøssingfjord, Norway during 2018 to evaluate long-term, legacy pollution effects of coastal mine tailing sea disposal activities. Nickel and copper sediment pollution in the mine tailing sea disposal area was classified as moderate and severe, respectively, under Norwegian environmental quality standards, and highlights the persistent hazard and legacy impacts of heavy metals in these impacted fjord ecosystems. Mercury, zinc, and arsenic had stronger affinities to brown crab muscle likely due to the presence of thiols, and availability of metal binding sites. Our multi-isotopic composition data showed that lead isotopes were the most useful source apportionment tool for this fjord. Overall, our study highlights the importance and value of measuring several different heavy metals and multiple isotopic signatures in different crab organs and seafloor sediment to comprehensively evaluate fjord pollution and kinetic uptake dynamics. Brown crabs were suitable eco-indicators of benthic ecosystem heavy metal pollution in a fjord ecosystem still experiencing short- and long-term physical and chemical impacts from coastal mining sea disposal activities.

Urban vegetable contamination - The role of adhering particles and their significance for human exposure

While urban-grown vegetables could help combat future food insecurity, the elevated levels of toxic metals in urban soils need to be met with measures that minimise transfer to crops. This study firstly examines soil/dust particle inclusion in leafy vegetables and its contribution to vegetable metals (As, Ba, Cd, Co, Cr, Cu, Ni, Pb, Sb, and Zn), using vegetable, soil and dust data from an open-field urban farm in southeastern Sweden. Titanium concentrations were used to assess soil/dust adherence. Results showed that vegetables contained 0.05-1.3 wt% of adhering particles (AP) even after washing. With 0.5 % AP, an adult with an average intake of vegetables could ingest approximately 100 mg of particles per day, highlighting leafy vegetables as a major route for soil/dust ingestion. The presence of adhering particles also significantly contributed to the vegetable concentrations of As (9-20 %), Co (17-20 %), Pb (25-29 %), and Cr (33-34 %). Secondly, data from an indoor experiment was used to characterise root metal uptake from 20 urban soils from Sweden, Denmark, Spain, the UK, and the Czech Republic. Combining particle adherence and root uptake data, vegetable metal concentrations were calculated for the 20 urban soils to represent hypothetical field scenarios for these. Subsequently, average daily doses were assessed for vegetable consumers (adults and 3-6 year old children), distinguishing between doses from adhering particles and root uptake. Risks were evaluated from hazard quotients (HQs; average daily doses/tolerable intakes). Lead was found to pose the greatest risk, where particle ingestion often resulted in HQs > 1 across all assessed scenarios. In summary, since washing was shown to remove only a portion of adhering metal-laden soil/dust particles from leafy vegetation, farmers and urban planners need to consider that measures to limit particle deposition are equally important as cultivating in uncontaminated soil.

137Cs and isotopic ratios of Pu and U in lichens and mosses from Russian Arctic areas

Knowledge of past anthropogenic sources of radionuclide contamination in Russian Arctic areas is important to assess the radioecological situation of these less-studied regions. Therefore, we investigated the sources of radionuclide contamination in Russian Arctic in the 1990s. Lichen and moss samples were collected from 1993 to 1996 in Kola Peninsula, Franz Josef Land, and few other locations. The activity concentration of 137Cs was determined from the archived samples by gamma spectrometry in 2020. After radiochemical separation of Pu and U isotopes from the lichens and mosses, mass ratios 240Pu/239Pu, 234U/238U, 235U/238U, and 236U/238U were determined by mass spectrometry. 137Cs activity concentrations at the sampling date were found to vary from 3.1 ± 1.4 (Inari, Finnish-Russian border) to 303 ± 7 (Kola Peninsula) Bq/kg. The ranges of isotopic ratios were 0.0592 ± 0.0007 to 0.253 ± 0.082 for 240Pu/239Pu, (4.89 ± 3.91) × 10-5 to (6.86 ± 0.04) × 10-5 for 234U/238U, 0.0072104(21) to 0.007376(41) for 235U/238U, and from below 1 × 10-7 to (2.65 ± 0.19) × 10-6 for 236U/238U, respectively. Based on the measured isotopic ratios and characteristic isotopic ratios of known contamination sources, the main Pu and U sources in the sampled lichens and mosses are global fallout, the Chernobyl accident, and possibly local nuclear activities. These results contribute to further understanding of past nuclear events and resulting nuclear contamination in Russian Arctic terrestrial areas.

Lead exposure in brown bears is linked to environmental levels and the distribution of moose kills

Lead (Pb) is heterogeneously distributed in the environment and multiple sources like Pb ammunition and fossil fuel combustion can increase the risk of exposure in wildlife. Brown bears (Ursus arctos) in Sweden have higher blood Pb levels compared to bears from other populations, but the sources and routes of exposure are unknown. The objective of this study was to quantify the contribution of two potential sources of Pb exposure in female brown bears (n = 34 individuals; n = 61 samples). We used multiple linear regressions to determine the contribution of both environmental Pb levels estimated from plant roots and moose (Alces alces) kills to blood Pb concentrations in female brown bears. We found positive relationships between blood Pb concentrations in bears and both the distribution of moose kills by hunters and environmental Pb levels around capture locations. Our results suggest that the consumption of slaughter remains discarded by moose hunters is a likely significant pathway of Pb exposure and this exposure is additive to environmental Pb exposure in female brown bears in Sweden. We suggest that spatially explicit models, incorporating habitat selection analyses of harvest data, may prove useful in predicting Pb exposure in scavengers.

Multi-Element Assessment of Potentially Toxic and Essential Elements in New and Traditional Food Varieties in Sweden

With the global movement toward the consumption of a more sustainable diet that includes a higher proportion of plant-based foods, it is important to determine how such a change could alter the intake of cadmium and other elements, both essential and toxic. In this study, we report on the levels of a wide range of elements in foodstuffs that are both traditional and "new" to the Swedish market. The data were obtained using analytical methods providing very low detection limits and include market basket data for different food groups to provide the general levels in foods consumed in Sweden and to facilitate comparisons among traditional and "new" food items. This dataset could be used to estimate changes in nutritional intake as well as exposure associated with a change in diet. The concentrations of known toxic and essential elements are provided for all the food matrices studied. Moreover, the concentrations of less routinely analyzed elements are available in some matrices. Depending on the food variety, the dataset includes the concentrations of inorganic arsenic and up to 74 elements (Ag, Al, As, Au, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cs, Cu, Fe, Ga, Ge, Hf, Hg, K, Li, Mg, Mn, Mo, Na, Nb, Ni, P, Pb, Rb, S, Sb, Sc, Se, Si, Sn, Sr, Ta, Te, Th, Ti, Tl, U, W, V, Y, Zn, Zr, rare Earth elements (REEs) (Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tb, Tm, and Yb), platinum group elements (PGEs) (Ir, Os, Pd, Pr, Pt, Re, Rh, Ru, and Pr), and halogens (Br, Cl, and I)). The main focus (and thus the most detailed information on variation within a given food group) is on foods that are currently the largest contributors to dietary cadmium exposure in Sweden, such as pasta, rice, potato products, and different sorts of bread. Additionally, elemental concentrations in selected food varieties regarded as relatively new or "novel" to the Swedish market are provided, including teff flour, chia seeds, algae products, and gluten-free products.

Toxic elements in arctic and sub-arctic brown bears: Blood concentrations of As, Cd, Hg and Pb in relation to diet, age, and human footprint

Contamination with arsenic (As), cadmium (Cd), mercury (Hg) and lead (Pb) is a global concern impairing resilience of organisms and ecosystems. Proximity to emission sources increases exposure risk but remoteness does not alleviate it. These toxic elements are transported in atmospheric and oceanic pathways and accumulate in organisms. Mercury accumulates in higher trophic levels. Brown bears (Ursus arctos), which often live in remote areas, are long-lived omnivores, feeding on salmon (Oncorhynchus spp.) and berries (Vaccinium spp.), resources also consumed by humans. We measured blood concentrations of As, Cd, Hg and Pb in bears (n = 72) four years and older in Scandinavia and three national parks in Alaska, USA (Lake Clark, Katmai and Gates of the Arctic) using high-resolution, inductively-coupled plasma sector field mass spectrometry. Age and sex of the bears, as well as the typical population level diet was associated with blood element concentrations using generalized linear regression models. Alaskan bears consuming salmon had higher Hg blood concentrations compared to Scandinavian bears feeding on berries, ants (Formica spp.) and moose (Alces). Cadmium and Pb blood concentrations were higher in Scandinavian bears than in Alaskan bears. Bears using marine food sources, in addition to salmon in Katmai, had higher As blood concentrations than bears in Scandinavia. Blood concentrations of Cd and Pb, as well as for As in female bears increased with age. Arsenic in males and Hg concentrations decreased with age. We detected elevated levels of toxic elements in bears from landscapes that are among the most pristine on the planet. Sources are unknown but anthropogenic emissions are most likely involved. All study areas face upcoming change: Increasing tourism and mining in Alaska and more intensive forestry in Scandinavia, combined with global climate change in both regions. Baseline contaminant concentrations as presented here are important knowledge in our changing world.

Managing health risks in urban agriculture: The effect of vegetable washing for reducing exposure to metal contaminants

A common, yet poorly evaluated, advice to remove contaminants from urban vegetables is to wash the produce before consumption. This study is based on 63 samples of chard, kale, lettuce and parsley that have grown near a heavily trafficked road in the third largest city in Sweden, with one portion of each sample being analysed without first being washed, and the other portion being subjected to common household washing. Concentrations of 71 elements were analysed by ICP-SFMS after a sample digestion that dissolves both the plant tissues and all potentially adhering particles. The results show that the washing effect, or the fraction removed upon washing, varies significantly between elements: from approximately 0 % for K to 68 % for the ∑REEs. Considering traditional metal contaminants, the efficiency decreased from Pb (on average 56 % lost) to Co (56 %) > Cr (55 %) > As (45 %) > Sb (35 %) > Ni (33 %) > Cu (13 %) > Zn (7 %) > Cd (7 %), and Ba (5 %). A clear negative correlation between the washing effect and the different elements' bioconcentration factors shows that the elements' accessibility for plant uptake is a key controlling factor for the degree to which they are removed upon washing. Based on the average washing efficiencies seen in this study, the average daily intake of Pb would increase by 130 % if vegetables are not washed prior to consumption. For the other contaminant metals this increase corresponds to 126 % (Co), 121 % (Cr), 82 % (As), 55 % (Sb), 50 % (Ni), 16 % (Cu), 8 % (Zn), 7 % (Cd) and 5 % (Ba). The advice to wash vegetables is therefore, for many elements, highly motivated for reducing exposure and health risks. For elements which are only slightly reduced when the vegetables are washed, however, advising should rather focus on reducing levels of contamination in the soil itself.

A comprehensive evaluation of sulfur isotopic analysis (δ34S and δ33S) using multi-collector ICP-MS with characterization of reference materials of geological and biological origin

Sulfur isotope ratios are often used as biogeochemical tracers to gain understanding of abiotic and biological processes involved in the sulfur cycle in both modern and ancient environments. There is however a lack of matrix-matched well-characterized isotopic reference materials that are essential for controlling the accuracy and precision. This study therefore focused on expanding and complementing the currently available sulfur isotope ratio data by providing the bulk sulfur isotopic composition, as determined using multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS), for a comprehensive set of commercially and/or readily available biological and geological reference materials. A total 7 isotopic reference materials and 41 elemental reference materials were studied. These reference materials include standards of terrestrial and marine animal origin, terrestrial plant origin, human origin, and geological origin. Different sample preparation protocols, including digestion and subsequent chromatographic isolation of S, were evaluated and the optimum approach selected for each matrix type. For achieving enhanced robustness, the sample preparation and sulfur isotope ratio measurements were done at two different laboratories for selected reference materials, while at one of the laboratories the measurements were additionally performed using two different MC-ICP-MS instruments. Determined δ³⁴S_VCDT and δ³³S_VCDT values compared well between the different laboratories, as well as between the different generation MC-ICP-MS instruments, and for standards that were previously characterized, our data are similar to literature values. The δ³⁴S_VCDT ranges determined for the different categories of the reference materials - terrestrial animal origin: +2 to +9‰, marine animal origin: +15 to +20‰, human origin: +6 to +10‰, terrestrial plant origin: -20 to +7‰, and geological origin: -12 to +21‰ - fit the expected values based on previous studies of similar types of matrices well. No significant mass-independent fractionation is observed when considering the expanded uncertainties for Δ³³S_V-CDT.

Future food contaminants: An assessment of the plant uptake of Technology-critical elements versus traditional metal contaminants

Technology-critical elements (TCEs) include most rare earth elements (REEs), the platinum group elements (PGEs), and Ga, Ge, In, Nb, Ta, Te, and Tl. Despite increasing recognition of their prolific release into the environment, their soil to plant transfer remains largely unknown. This paper provides an approximation of the potential for plant uptake by calculating bioconcentration factors (BCFs), defined as the concentration in edible vegetable tissues relative to that in cultivation soil. Here data were obtained from an indoor cultivation experiment growing lettuce, chard, and carrot on 22 different European urban soils. Values of BCFs were determined from concentrations of TCEs in vegetable samples after digestion with concentrated HNO3, and from concentrations in soil determined after 1) Aqua Regia digestion and, 2) diluted (0.1 M) HNO3 leaching. For comparison, BCFs were also determined for 5 traditional metal contaminants (TMCs; As, Cd, Cu, Pb, and Zn). The main conclusions of the study were that: 1)BCF values for the REEs were consistently low in the studied vegetables;2)the BCFs for Ga and Nb were low as well;3) the BCFs for Tl were high relative to the other measured TCEs and the traditional metal contaminants; and 4) mean BCF values for the investigated TCEs were generally highest in chard and lowest in carrot. These findings provide initial evidence that there are likely to be real and present soil-plant transfer of TCEs, especially in the case of Tl. Improvements in analytical methods and detection limits will allow this to be further investigated in a wider variety of edible plants so that a risk profile may be developed.

Longitudinal isotope ratio variations in human hair and nails

Due to the straightforward and non-invasive sampling, ease of transport and long-term storage and access to time-resolved information, determination of element concentrations and isotope ratios in hair and nails finds increasing use. Multi-isotopic information preserved in keratinous tissues allows one to reveal dietary, physiological and environmental influences, but progress in this area is still limited by complicated and time-consuming analytical procedures and challenges in accuracy assessment. In this study, longitudinal distributions of δ³⁴S, ⁸⁷Sr/⁸⁶Sr, ^207,208Pb/²⁰⁶Pb, δ⁶⁶Zn, δ⁵⁶Fe, δ⁶⁵Cu, δ²⁶Mg, and δ¹¹⁴Cd were obtained for hair and nails collected from nine subjects with different age, biological sex, diet and/or place of residence. For S and Zn, the distribution along hair strands revealed a trend towards a heavier isotopic signature from the proximal to the distal end, with a maximum difference within the hair of a single subject of 1.2‰ (Δ³⁴S) and 0.4‰ (Δ⁶⁶Zn). For Fe, Cu, Mg and Cd, a shift towards either a lighter (Cu) or heavier (Fe, Mg and Cd) isotopic composition is accompanied by increasing concentration towards the distal hair end, indicating possible isotope fractionation during deposition or external contamination with a different isotopic composition. Pb and Sr isotope ratios are relatively stable throughout the hair strands despite notable concentration increases towards the distal end, likely reflecting external contamination. The isotopic composition of Sr points to tap water as a probable main source, explaining the relative stability of the ratio for individuals from the same geographical location. For Pb, isotopic compositions suggest tap water and/or indoor dust as possible sources. Similar δ³⁴S, ⁸⁷Sr/⁸⁶Sr, ^207,208Pb/²⁰⁶Pb, δ⁶⁶Zn, δ⁵⁶Fe, and δ⁶⁵Cu observed for hair, fingernails and toenails sampled from the same individual suggest that keratinous tissues are conservative receivers of internal and external inputs and can be used complementary. Seasonal variation in δ³⁴S, ^207,208Pb/²⁰⁶Pb, and δ⁶⁵Cu was observed for fingernails.

Early diagenesis of anthropogenic uranium in lakes receiving deep groundwater from the Kiruna mine, northern Sweden

The uranium (U) concentrations and isotopic composition of waters and sediment cores were used to investigate the transport and accumulation of U in a water system (tailings pond, two lakes, and the Kalix River) receiving mine waters from the Kiruna mine. Concentrations of dissolved U decrease two orders of magnitude between the inflow of mine waters and in the Kalix River, while the concentration of the element bound to particulate matter increases, most likely due to sorption on iron‑manganese hydroxides and organic matter. The vertical distribution of U in the water column differs between two polluted lakes with a potential indication of dissolved U supply from sediment's pore waters at anoxic conditions. Since the beginning of exposure in the 1950s, U concentrations in lake sediments have increased >20-fold, reaching concentrations above 50 μg g-1. The distribution of anthropogenic U between the lakes does not follow the distribution of other mine water contaminants, with a higher relative proportion of U accumulating in the sediments of the second lake. Concentrations of redox-sensitive elements in the sediment core as well as Fe isotopic composition were used to re-construct past redox-conditions potentially controlling early diagenesis of U in surface sediments. Two analytical techniques (ICP-SFMS and MC-ICP-MS) were used for the determination of U isotopic composition, providing an extra dimension in the understanding of processes in the system. The (234 U)/(238 U) activity ratio (AR) is rather uniform in the tailings pond but varies considerably in water and lake sediments providing a potential tracer for U transport from the Kiruna mine through the water system, and U immobilization in sediments. The U mass balance in the Rakkurijoki system as well as the amount of anthropogenic U accumulated in lake sediments were evaluated, indicating the immobilization in the two lakes of 170 kg and 285 kg U, respectively.

High concentrations of lead (Pb) in blood and milk of free-ranging brown bears (Ursus arctos) in Scandinavia

Exposure to lead (Pb) is a global health problem for both humans and wildlife. Despite a dramatic decline in human Pb exposure following restrictions of leaded gasoline and industry and thereby an overall reduction of Pb entering the environment, Pb exposure continues to be a problem for wildlife species. Literature on scavenging terrestrial mammals, including interactions between Pb exposure and life history, is however limited. We quantified Pb concentration in 153 blood samples from 110 free-ranging Scandinavian brown bears (Ursus arctos), 1-25 years old, using inductively coupled plasma sector field mass spectrometry. We used generalized linear models to test effects of age, body mass, reproduction status and spatial distribution on the blood Pb concentrations of 56 female bears. We sampled 28 females together with 56 dependent cubs and paired their blood Pb concentrations. From 20 lactating females, we measured the Pb concentration in milk. The mean blood Pb concentration was 96.6 μg/L (range: 38.7-220.5 μg/L). Both the mean and range are well above established threshold concentrations for developmental neurotoxicity (12 μg/L), increased systolic blood pressure (36 μg/L) and prevalence of kidney disease in humans (15 μg/L). Lactating females had higher Pb blood concentrations compared to younger, non-lactating females. Blood Pb concentrations of dependent cubs were correlated with their mother's blood Pb concentration, which in turn was correlated with the Pb concentration in the milk. Life-long Pb exposure in Scandinavian brown bears may have adverse effects both on individual and population levels. The high blood Pb concentrations found in brown bears contrast the general reduction in environmental Pb contamination over the past decades in Scandinavia and more research is needed to identify the sources and pathways of Pb exposure in the brown bears.

Low-level environmental metal pollution is associated with altered gut microbiota of a wild rodent, the bank vole (Myodes glareolus)

Mining and related industries are a major source of metal pollution. In contrast to the well-studied effects of exposure to metals on animal physiology and health, the impacts of environmental metal pollution on the gut microbiota of wild animals are virtually unknown. As the gut microbiota is a key component of host health, it is important to understand whether metal pollution can alter wild animal gut microbiota composition. Using a combination of 16S rRNA amplicon sequencing and quantification of metal levels in kidneys, we assessed whether multi-metal exposure (the sum of normalized levels of fifteen metals) was associated with changes in gut microbiota of wild bank voles (Myodes glareolus) from two locations in Finland. Exposure to increased metal load was associated with higher gut microbiota species diversity (α-diversity) and altered community composition (β-diversity), but not dispersion. Multi-metal exposure and increased levels of several metals (Cd, Hg, Pb and Se) were associated with differences in the abundance of microbial taxa, especially those within the families Clostridiales vadinBB60 group, Desulfovibrionaceae, Lachnospiraceae, Muribaculaceae and Ruminococcaceae. Our data indicate that even low-level metal pollution can affect the diversity of microbiota and be associated with deterministic differences in composition of host gut microbiota in wild animal populations. These findings highlight the need to study a broader range of metals and their cocktails that are more representative of the types of environmental exposure experienced by wild animals.

Trace and major elements in food supplements of different origin: Implications for daily intake levels and health risks

As the use of food supplements increases, voices are being raised questioning the safety of these products. As a contribution to understanding the trace and major elemental composition of food supplements and their potential health risks, this study presents concentrations of 71 elements in 138 supplements, categorised into synthetic products and three groups of products with natural ingredients. Concentrations were converted into average daily doses (ADDs) and compared to tolerable daily intakes (TDIs). For elements where we found significant ADDs relative to the TDI a comparison was also made to the normal dietary intake. Our main findings are that: 1) Most elements display highly variable concentrations in food supplements; more so than in normal foodstuff; 2) For ten of the analysed elements some products rendered ADDs > 50 % of the TDI. Half of the elements were essential (Fe, Mn, Se, Mo, Zn), and as such motivated in food supplements. The other half (As, Pb, Cd, Al, Ni) represent non-essential and highly toxic elements, where the occurrence in food supplements ought to be viewed as contamination. Although none of these toxic metals were declared on any product's table of content, several products gave high ADDs - in several cases even exceeding the TDIs; 3) The risk of reaching high ADDs for the toxic elements is strongly associated with products that contain marine ingredients (e.g. algae, mussels etc), and to some degree products of terrestrial plant-based origin. The health of consumers would benefit if food regulatory frameworks were updated to better address the risks of food supplements occasionally being contaminated with different toxic metals, for example by setting maximum permissible concentrations for a longer list of elements.

Spatio-temporal variation of metals and organic contaminants in bank voles (Myodes glareolus)

Environmental contamination with metals and organic compounds is of increasing concern for ecosystem and human health. Still, our knowledge about spatial distribution, temporal changes and ecotoxicological fate of metals and organic contaminants in wildlife is limited. We studied concentrations of 69 elements and 50 organic compounds in 300 bank voles (Myodes glareolus), Europe's most common mammal, sampled in spring and autumn 2017-2018 in five monitoring areas, representing three biogeographic regions. In addition, we compared measured concentrations with previous results from bank voles sampled within the same areas in 1995-1997 and 2001. In general, our results show regional differences, but no consistent patterns among contaminants and study areas. The exception was for the lowest concentrations of organic contaminants (e.g. perfluorooctane sulfonate, PFOS), which were generally found in the northern Swedish mountain area. Concentrations of metals and organic contaminants in adults varied seasonally with most organic contaminants being higher in spring; likely induced by diet shifts but potentially also related to age differences. In addition, metal concentrations varied between organs (liver vs. kidney), age classes (juveniles vs. adults; generally higher in adults) as well as between males and females. Concentrations of chromium and nickel in kidney and liver in the northernmost mountain area were lower in 2017-2018 than in 1995-1997 and in three of four areas, lead concentrations were lower in 2017-2018 than in 2001. Current metal concentrations (except mercury) are not expected to negatively affect the voles. Concentrations of hexachlorobenzene displayed highest concentrations in 2001 in the mountains, while it was close to detection limit in 2017-2018. Likewise, PFOS concentrations decreased in the mountains and in south-central lowland forests between 2001 and 2017-2018. Our results suggest that season, age class and sex need to be considered when designing and interpreting results from monitoring programs targeting inorganic and organic contaminants in wildlife.

Assessment of the LeadCare® Plus for Use on Scandinavian Brown Bears (Ursus arctos)

Lead (Pb) exposure is associated with adverse health effects in both humans and wildlife. Blood lead levels (BLL) of sentinel wildlife species can be used to monitor environmental lead exposure and ecosystem health. BLL analyzers, such as the LeadCare®, are validated for use in humans, assessed for use in some avian species and cattle, and are increasingly being used on wildlife to monitor lead exposure. The LeadCare® analyzers use a technique called anodic stripping voltammetry (ASV). Species-specific conversion equations have been proposed to approximate the levels found with gold standard measuring methods such as inductively coupled plasma mass spectrometry (ICP-MS) because the ASV method has been shown to underestimate BLL in some species. In this study we assessed the LeadCare® Plus (LCP) for use on Scandinavian brown bears (Ursus arctos). LCP measurements were correlated with ICP-MS with a Bland-Altman analyzed bias of 16.3-22.5%, showing a consistent overestimation of BLL analyzed with LCP. Based on this analysis we provide conversion equations for calculating ICP-MS BLL based on the LCP results in Scandinavian brown bears. Our study shows that the LeadCare® Plus can be used for monitoring of lead exposure by approximating gold standard levels using conversion equations. This enables comparison with other gold standard measured BLL within the observed range of this study (38.20-174.00 μg/L). Our study also found that Scandinavian brown bears are highly exposed to environmental lead.

An apple a day? Assessing gardeners' lead exposure in urban agriculture sites to improve the derivation of soil assessment criteria

Globally, many of our urban agriculture sites (UAS) contain high levels of lead (Pb), a contaminant of toxicological concern to humans. To improve the derivation of soil assessment criteria at UAS, and avoid inappropriate closure of these valuable community spaces, we sampled nearly 280 paired soil and crop samples across 31 UAS gardens. This sampling was coupled with an exposure and food frequency questionnaire and participants blood Pb levels (BLL), (43 gardeners and 29 non-gardening neighbours). In 98% of the sampled soils, Pb concentrations were above the current UK soil guideline for UAS (80 mg/kg), however despite the high soil Pb (geometric mean: 324 mg/kg), and high soil bioaccessible Pb (geometric mean: 58.7%), all participants BLL were <4.1 μg/dL (range: 0.6-4.1 μg/dL). Indeed, there was no statistically significant difference between the BLL of the UAS gardeners and those of their non-gardening neighbours (p = 0.569). Pb uptake, however, varied with crop type and our study highlights the suitability of certain crops for growing at UAS with elevated Pb (e.g. tubers, shrub and tree fruit), whilst limiting the consumption of others (selected root vegetables, such as rhubarb, beetroot, parsnips and carrots, with observed Pb concentrations > 0.1 mg/kg FW). The importance of defining the exposure scenario of a specific sub-population (i.e. UAS gardeners) is highlighted. Our preferred models predict site specific assessment criteria (SSAC) of 722-1634 mg/kg. We found fruit and vegetable consumption rates by all participants, and not just the UAS gardeners, to be considerably higher than those currently used to derive the UK's category 4 screening levels (C4SLs). Furthermore, the soil to plant concentration factors (SPCFs) used to derive the UAS C4SL significantly over predict Pb uptake. Our study indicates it may be appropriate to develop a distinct exposure dataset for UAS. In particular we recommend the derivation of SPCFs that are reflective of urban soils, both in terms of the range of soil Pb concentrations typically observed, but also the sources (and hence human oral bioaccessibility and plant-availability) of this Pb.

Seasonal shift of diet in bank voles explains trophic fate of anthropogenic osmium?

Diet shifts are common in mammals and birds, but little is known about how such shifts along the food web affect contaminant exposure. Voles are staple food for many mammalian and avian predators. There is therefore a risk of transfer of contaminants accumulated in voles within the food chain. Osmium is one of the rarest earth elements with osmium tetroxide (OsO₄) as the most toxic vapor-phase airborne contaminant. Anthropogenic OsO₄ accumulates in fruticose lichens that are important winter food of bank voles (Myodes glareolus). Here, we test if a) anthropogenic osmium accumulates in bank voles in winter, and b) accumulation rates and concentrations are lower in autumn when the species is mainly herbivorous. Our study, performed in a boreal forest impacted by anthropogenic osmium, supported the hypotheses for all studied tissues (kidney, liver, lung, muscle and spleen) in 50 studied bank voles. In autumn, osmium concentrations in bank voles were even partly similar to those in the graminivorous field vole (Microtus agrestis; n=14). In autumn but not in late winter/early spring, osmium concentrations were generally negatively correlated with body weight and root length of the first mandible molar, i.e. proxies of bank vole age. Identified negative correlations between organ-to-body weight ratios and osmium concentrations in late winter/early spring indicate intoxication. Our results suggest unequal accumulation risk for predators feeding on different cohorts of bank voles.

Application of double-focusing sector field ICP-MS for determination of ultratrace constituents in samples characterized by complex composition of the matrix

The performance of double focusing, sector field mass spectrometry (ICP-SFMS) for determination of analytes, including technology critical elements (TCE), at ultra-trace levels in environmental and clinical matrices was critically evaluated. Different configurations of the ICP-SFMS introduction system as well as various sample preparations, pre-concentration and matrix separation methods were employed and compared. Factors affecting detection capabilities and accuracy of data produced (instrumental sensitivity, contamination risks, purity of reagents, spectral interferences, matrix effects, analyte recovery and losses) were discussed. Optimized matrix-specific methods were applied to a range of reference and control materials (riverine, brackish and seawaters; whole blood, serum and urine) as well as tap water and snow samples collected in the area of Luleå city, northern Sweden; brackish and seawater from the Laptev Sea; venous blood samples with a special emphasis on determination of Au, Ag, Ir, Os, Pd, Pt, Re, Rh, Ru, Sb and Te. Even though these low abundant elements are relatively under-documented, the results produced were compared with published data, where available.

Heavy metal contamination of prenatal vitamins

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Toxic elements are found in prenatal vitamins with lead at unacceptable levels in more than half of the products tested.

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Arsenic is also found in some products at unsafe levels.

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Thallium is present at levels in some products that are not acceptable.

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Some products have very low level, which are safer, and recommendations are made to have industry (self regulatory) and government oversight to have the least contamination of prenatal vitamins.

Prenatal vitamins are often consumed daily during gestation and postnatally for up to 18–24 months with the belief that supplementation achieves better outcomes. Detrimental effects of gestational exposure to adverse chemical agents are gathering increasing attention. This study was designed to assess toxic element contamination in prenatal supplements.

Twenty-six commonly used prenatal vitamin brands including one prescription brand were collected from Canadian health-food outlets and pharmacies, and tested for toxic element contamination. Results were compared to established endpoints.

All samples contained Lead with average amounts being (0.535 μgm), 20/51 samples exceeded established standards for lead toxicity (0.50 μgm/day), with one sample yielding 4. μgm/day. Three samples registered inorganic arsenic levels above acceptable limits. Cadmium levels did not exceed current standards. Toxic elements such as Aluminum, Nickel, Titanium and Thallium were detected in all samples.

Cumulative intake of prenatal supplement over many months may constitute a significant source of toxic element exposure to the mother and offspring. With several samples exceeding known standards for gestational toxic element exposure, guidelines for routine monitoring and reporting are required. In keeping with recommendations from the International Federation of Obstetrics and Gynecology, industry regulation would be welcomed to protect expectant mothers and their vulnerable offspring.

Sublethal Lead Exposure Alters Movement Behavior in Free-Ranging Golden Eagles

Lead poisoning of animals due to ingestion of fragments from lead-based ammunition in carcasses and offal of shot wildlife is acknowledged globally and raises great concerns about potential behavioral effects leading to increased mortality risks. Lead levels in blood were correlated with progress of the moose hunting season. Based on analyses of tracking data, we found that even sublethal lead concentrations in blood (25 ppb, wet weight), can likely negatively affect movement behavior (flight height and movement rate) of free-ranging scavenging Golden Eagles (Aquila chrysaetos). Lead levels in liver of recovered post-mortem analyzed eagles suggested that sublethal exposure increases the risk of mortality in eagles. Such adverse effects on animals are probably common worldwide and across species, where game hunting with lead-based ammunition is widespread. Our study highlights lead exposure as a considerably more serious threat to wildlife conservation than previously realized and suggests implementation of bans of lead ammunition for hunting.

Feed premix: a difficult matrix for the accurate determination of trace elements - the outcome of IMEP-114 and IMEP-36

This paper presents the outcome of two proficiency tests (IMEP-114/36) running in parallel, which focused on the determination of total As, Cd, Pb, Hg and Sn in feed premixes. Both exercises aimed to test the performance of laboratories measuring trace elements in feed, in compliance with Directive 2002/32/EC of the European Parliament and of the Council on undesirable substances in animal feed. IMEP-114 was run for the European Union National Reference Laboratories, while IMEP-36 was open to all food control laboratories that wished to participate. In total 80 laboratories from 37 countries registered to both proficiency tests, from which 75 laboratories reported results. The test material used in this exercise was commercially available feed premix, which was processed, bottled, labelled and dispatched to participants. The performance of the participating laboratories was similar in both proficiency tests and was very good in the case of total Cd and less satisfactory for total As and total Pb. For total Sn only one-third of the participants reported results, from which 33% performed satisfactorily. Thirty-four participants reported results for total Hg, although the expert laboratories stated that the mass fraction for that measurand was below the limit of detection of the method used. An evaluation of the reasons that could be at the basis of unsatisfactory results has been carried out and is presented here.

The benefits and risks of consuming brewed tea: beware of toxic element contamination

Background. Increasing concern is evident about contamination of foodstuffs and natural health products. Methods. Common off-the-shelf varieties of black, green, white, and oolong teas sold in tea bags were used for analysis in this study. Toxic element testing was performed on 30 different teas by analyzing (i) tea leaves, (ii) tea steeped for 3-4 minutes, and (iii) tea steeped for 15-17 minutes. Results were compared to existing preferred endpoints. Results. All brewed teas contained lead with 73% of teas brewed for 3 minutes and 83% brewed for 15 minutes having lead levels considered unsafe for consumption during pregnancy and lactation. Aluminum levels were above recommended guidelines in 20% of brewed teas. No mercury was found at detectable levels in any brewed tea samples. Teas contained several beneficial elements such as magnesium, calcium, potassium, and phosphorus. Of trace minerals, only manganese levels were found to be excessive in some black teas. Conclusions. Toxic contamination by heavy metals was found in most of the teas sampled. Some tea samples are considered unsafe. There are no existing guidelines for routine testing or reporting of toxicant levels in "naturally" occurring products. Public health warnings or industry regulation might be indicated to protect consumer safety.

The role of bacterial consortium and organic amendment in Cu and Fe isotope fractionation in plants on a polluted mine site

Copper and iron isotope fractionation by plant uptake and translocation is a matter of current research. As a way to apply the use of Cu and Fe stable isotopes in the phytoremediation of contaminated sites, the effects of organic amendment and microbial addition in a mine-spoiled soil seeded with Helianthus annuus in pot experiments and field trials were studied. Results show that the addition of a microbial consortium of ten bacterial strains has an influence on Cu and Fe isotope fractionation by the uptake and translocation in pot experiments, with an increase in average of 0.99 ‰ for the δ(65)Cu values from soil to roots. In the field trial, the amendment with the addition of bacteria and mycorrhiza as single and double inoculation enriches the leaves in (65)Cu compared to the soil. As a result of the same trial, the δ(56)Fe values in the leaves are lower than those from the bulk soil, although some differences are seen according to the amendment used. Siderophores, possibly released by the bacterial consortium, can be responsible for this change in the Cu and Fe fractionation. The overall isotopic fractionation trend for Cu and Fe does not vary for pot and field experiments with or without bacteria. However, variations in specific metabolic pathways related to metal-organic complexation and weathering can modify particular isotopic signatures.

Blood, urine, and sweat (BUS) study: monitoring and elimination of bioaccumulated toxic elements

There is limited understanding of the toxicokinetics of bioaccumulated toxic elements and their methods of excretion from the human body. This study was designed to assess the concentration of various toxic elements in three body fluids: blood, urine and sweat. Blood, urine, and sweat were collected from 20 individuals (10 healthy participants and 10 participants with various health problems) and analyzed for approximately 120 various compounds, including toxic elements. Toxic elements were found to differing degrees in each of blood, urine, and sweat. Serum levels for most metals and metalloids were comparable with those found in other studies in the scientific literature. Many toxic elements appeared to be preferentially excreted through sweat. Presumably stored in tissues, some toxic elements readily identified in the perspiration of some participants were not found in their serum. Induced sweating appears to be a potential method for elimination of many toxic elements from the human body. Biomonitoring for toxic elements through blood and/or urine testing may underestimate the total body burden of such toxicants. Sweat analysis should be considered as an additional method for monitoring bioaccumulation of toxic elements in humans.

Determination of total chlorine and bromine in solid wastes by sintering and inductively coupled plasma-sector field mass spectrometry

A sample preparation method based on sintering, followed by analysis by inductively coupled plasma-sector field mass spectrometry (ICP-SFMS) for the simultaneous determination of chloride and bromide in diverse and mixed solid wastes, has been evaluated. Samples and reference materials of known composition were mixed with a sintering agent containing Na(2)CO(3) and ZnO and placed in an oven at 560 degrees C for 1h. After cooling, the residues were leached with water prior to a cation-exchange assisted clean-up. Alternatively, a simple microwave-assisted digestion using only nitric acid was applied for comparison. Thereafter the samples were prepared for quantitative analysis by ICP-SFMS. The sintering method was evaluated by analysis of certified reference materials (CRMs) and by comparison with US EPA Method 5050 and ion chromatography with good agreement. Median RSDs for the sintering method were determined to 10% for both chlorine and bromine, and median recovery to 96% and 97%, respectively. Limits of detection (LODs) were 200mg/kg for chlorine and 20mg/kg for bromine. It was concluded that the sintering method is suitable for chlorine and bromine determination in several matrices like sewage sludge, plastics, and edible waste, as well as for waste mixtures. The sintering method was also applied for determination of other elements present in anionic forms, such as sulfur, arsenic, selenium and iodine.

Levels of inorganic constituents in raw nuts and seeds on the Swedish market

The levels of approximately 70 elements were determined in different culinary nuts (hazelnuts, walnuts, almonds, bitter almonds, pecans, cashews, Brazil nuts, pistachios, pine nuts, peanuts and coconuts) and seeds (pumpkin and sunflower) available on the Swedish market. The study was limited to raw, virtually unprocessed nuts and seeds (both shelled and unshelled) excluding mixed, roasted or salted products. In total, 44 products from different suppliers were analyzed, with the number of samples per nut/seed variety reflecting the availability of unprocessed products in retail outlets, varying from two for bitter almonds and pistachios to six for hazelnuts and walnuts. This selection includes samples from at least 11 different countries of origin. The optimized analytical procedure consists of microwave-assisted sample digestion using a HNO3/HF mixture, followed by multi-elemental analysis by double focusing, sector field inductively coupled plasma mass spectrometry. The analyses were accompanied by rigorous quality control measures including thorough control of potential sample contamination at all analytical stages, participation in inter-laboratory performance assessment schemes, and the analysis of certified reference materials of plant origin. Concentrations thus obtained were compared with data from product labels (where available), food composition tables and other relevant surveys, demonstrating, depending on the elements in question, close agreement as well as considerable differences.

Osmium in environmental samples from Northeast Sweden. Part I. Evaluation of background status

Osmium (Os) concentrations and (187)Os/(188)Os isotope abundance ratios are presented for sedimentary materials, soils, humus, plants, mushrooms, mosses and lichens collected in the vicinity of the town of Luleå, Northeast Sweden, the data for biological specimens being the first reported. Contributions from sampling and varying exposure time to the observed environmental variability were evaluated. Sedimentary materials (from both fresh and brackish water) are most elevated in radiogenic (187)Os, followed by inorganic soil horizons, mushrooms and humus. The Os isotopic compositions of plants, mosses and lichens are much less radiogenic, with mean (187)Os/(188)Os lying within a relatively narrow 0.3-0.6 range. Significant temporal variations in Os concentrations and isotopic compositions of plant samples are attributed to integrative uptake of airborne Os with non-radiogenic composition. Measured Os concentrations in biological matrices increase in the order: small shrub leaves (blueberry and lingonberry)< or =spruce needles< or =mushrooms< or =tree leaves< or =pine needles<mosses<lichens. The concentrations found in three different species of plant were used to provide the first estimates of gaseous osmium tetroxide (OsO(4)) in the environment. Though the Os content of samples from Northeast Sweden does not differ significantly from matrix-matched international reference materials (not certified for Os) of abiotic origin, the estimates of gaseous OsO(4) concentrations are roughly an order of magnitude higher than have been reported for particle-bound Os in other studies. The pronounced spatial variations between relatively closely situated sites in mean (187)Os/(188)Os ratios for samples of the same species (presumably with the same dominating uptake mechanism) point to the presence of different local Os sources. This study therefore demonstrates that emissions of Os from automobile catalytic converters are not the only source of contemporary environmental contamination.

Osmium in environmental samples from Northeast Sweden. Part II. Identification of anthropogenic sources

Osmium (Os) concentrations and (187)Os/(188)Os isotope abundance ratios measured in epiphytic lichens from Northeast Sweden have been used for the identification of anthropogenic emission sources of this element. Based on isotope abundance ratios and similarities in spatial distributions between Os and chromium, smelters operated on chromium ores from Kemi deposits have shown to be the most important factor affecting the airborne Os burden in the region. The extent of the exposure is reflected by lichen concentrations near the source exceeding those from remote areas by a factor of 1000. Contributions from metal foundries processing iron, copper, lead and zinc ores can also be seen, though, because of lower Os concentrations in the feedstock, on a considerably lower scale. Masked by these industrial emissions in the studied area, the impact of Os originating from automotive catalytic converters cannot be resolved at present.

Ion-specific isotopic fractionation of molybdenum during diffusion in aqueous solutions

Experiments modeling diffusion of Mo in aqueous solutions have been performed and, using multicollector ICP-MS, the ratios of the diffusivities of Mo isotopes, D97Mo/ D95Mo, in aqueous solutions have been determined. Diffusion of MoO42- ions in solution was concomitant with Mo isotopic fractionation with D97Md/D95Mo = 0.99988+/-0.00004 (2sigma for n = 3). In contrast, during diffusion of Mo polyanions, such as Mo70246- and Mo8O264-, no measurable isotope fractionation has been found with D97Mo/D95MO = 1.00000 +/- 0.00002 (2sigma for n = 3). These results indicate the need for due consideration to Mo speciation when attempting to interpret the role of diffusive fluxes in the formation of Mo isotopic signatures in nature. They also raise the possibility that the various chemical forms of other transition metals may be characterized by species-specific isotopic fractionation effects during physicochemical reactions.

Authentication of Kalix (N.E. Sweden) vendace caviar using inductively coupled plasma-based analytical techniques: Evaluation of different approaches

Different analytical approaches for origin differentiation between vendace and whitefish caviars from brackish- and freshwaters were tested using inductively coupled plasma double focusing sector field mass spectrometry (ICP-SFMS) and multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). These approaches involve identifying differences in elemental concentrations or sample-specific isotopic composition (Sr and Os) variations. Concentrations of 72 elements were determined by ICP-SFMS following microwave-assisted digestion in vendace and whitefish caviar samples from Sweden (from both brackish and freshwater), Finland and USA, as well as in unprocessed vendace roe and salt used in caviar production. This data set allows identification of elements whose contents in caviar can be affected by salt addition as well as by contamination during production and packaging. Long-term method reproducibility was assessed for all analytes based on replicate caviar preparations/analyses and variations in element concentrations in caviar from different harvests were evaluated. The greatest utility for differentiation was demonstrated for elements with varying concentrations between brackish and freshwaters (e.g. As, Br, Sr). Elemental ratios, specifically Sr/Ca, Sr/Mg and Sr/Ba, are especially useful for authentication of vendace caviar processed from brackish water roe, due to the significant differences between caviar from different sources, limited between-harvest variations and relatively high concentrations in samples, allowing precise determination by modern analytical instrumentation. Variations in the 87Sr/86Sr ratio for vendace caviar from different harvests (on the order of 0.05-0.1%) is at least 10-fold less than differences between caviar processed from brackish and freshwater roe. Hence, Sr isotope ratio measurements (either by ICP-SFMS or by MC-ICP-MS) have great potential for origin differentiation. On the contrary, it was impossible to differentiate between Swedish caviar processed from brackish water roe and Finnish freshwater caviar based solely on 187Os/188Os ratios.

Methylmercury measurement in whole blood by isotope-dilution GC-ICPMS with 2 sample preparation methods

BACKGROUND

Despite its known toxicity, methylmercury is rarely measured directly in clinical studies; instead, conclusions are based on total mercury measurements. We have developed isotope-dilution-based methods for methylmercury-specific analysis of whole blood by coupled gas chromatography-inductively coupled plasma mass spectrometry (GC-ICPMS).

METHODS

We analyzed animal and human blood samples after alkaline digestion or extraction of methylmercury into dichloromethane and back extraction into water. Methylmercury was converted to the volatile ethyl derivative, purged, and trapped on a solid-phase collection medium, and then introduced into the GC-ICPMS system.

RESULTS

Limits of quantification were 0.4 and 0.03 microg/L at a signal-to-noise ratio of 10 with the alkaline digestion and extraction methods, respectively. Extraction met our selected acceptable total error criterion, with an SD of 0.58 microg/L at the critical maternal blood concentration of 5.8 microg/L. Results obtained with alkaline digestion indicated the need for improved random analytical uncertainty, which was achieved by increasing the enrichment of the isotope dilution. For 37 blood samples, the mean (SD) proportion of total mercury present as methylmercury was 60 (27)%, range 6%-100%.

CONCLUSIONS

The combination of extraction and isotope-dilution GC-ICPMS meets the requirements for use as a reference method for measuring methylmercury in whole blood.

Chromatographic Purification for the Determination of Dissolved Silicon Isotopic Compositions in Natural Waters by High-Resolution Multicollector Inductively Coupled Plasma Mass Spectrometry

A procedure is described for accurate Si isotope ratio measurements by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). Dissolved silicon was preconcentrated and separated from other elements present in natural surface waters using anion-exchange chromatography. The optimized procedure provides virtually complete elimination of major inorganic constituents while maintaining Si recovery in excess of 97%. High-resolution capabilities of MC-ICPMS used in this study allow interference-free measurements of 28Si and 29Si isotopes using conventional solution nebulization sample introduction without aerosol desolvation. Owing to the magnitude of polyatomic ion contributions in the region of mass 30, mostly from 14N16O+, measurements of the 30Si isotope can be affected by tailing of the interference signals, making exact matching of analyte and nitric acid concentrations in all measurement solutions mandatory. Isotope abundance ratio measurements were performed using the bracketing standards approach and on-line correction for mass-bias variations using an internal standard (Mg). Uncertainties, expressed as 95% confidence intervals, for replication of the entire procedure are better than +/-0.18/1000 for delta29Si and +/-0.5/1000 for delta30Si. For the first time with MC-ICPMS, the quality of Si isotope abundance ratio measurements could be verified using a three-isotope plot. All samples studied were isotopically heavier than the IRMM-018 Si isotopic reference material.

Measurement of iron and zinc isotopes in human whole blood: preliminary application to the study of HFE genotypes

Multi-collector inductively coupled plasma--sector field mass spectrometry was applied to the measurement of Fe and Zn isotopes in human whole blood samples. For the Fe present in the blood of healthy adults, enrichment of the lighter isotopes relative to a standard material was observed, in agreement with earlier studies. The level of fractionation was found to be lower in hemochromatosis patients exhibiting homozygous (C282Y/C282Y) mutation of the HFE gene. On the one hand, this reinforces the hypothesis that Fe fractionation in blood decreases with enhanced dietary absorption. On the other hand, this contradicts predictions made on the basis of determinations of Fe fractionation in blood samples collected from subjects characterized by milder HFE mutations. In healthy subjects, the Zn in blood is depleted in lighter isotopes, consistent with the limited number of prior observations. As for Fe, the Zn isotopic composition exhibited a tendency toward lower levels of fractionation in the blood of subjects with hereditary hemochromatosis with homozygous mutation (C282Y/C282Y) of the HFE gene. The results therefore suggest that both Fe and Zn isotopic signatures in whole blood, at least to some extent, reflect polymorphisms in the HFE gene.

Determination of low-abundance elements at ultra-trace levels in urine and serum by inductively coupled plasma?sector field mass spectrometry

A procedure is described for the determination of Y, Zr, Nb, Ru, Rh, Pd, Ag, Sb, Te, Hf, Ta, W, Re, Os, Ir, Pt, Au, Tl, Bi, and U in human urine and serum at concentrations relevant to the occupationally unexposed population. Sample preparation was limited to tenfold dilution with 2% HCl. A combination of a sample-introduction system designed to provide enhanced sensitivity and the use of water and acids of high-purity has resulted in limits of quantification (LOQ) in the sub-nanogram per liter range for 13 analytes. Instrumental background caused by release of analytes (Y, Zr, Ag, Sb, Au, Tl, Bi, U) from different parts of the sample-introduction system was found to be the major limitation in obtaining even better LOQ. Nevertheless, detection capabilities of the proposed procedure were adequate for all elements except Ru, Pd, and Rh. Despite of the use of high-resolution mode for these analytes some unresolved spectral interferences might still be present. For 13 elements an external accuracy assessment was accomplished by participation in proficiency testing and inter-comparison programs. Results obtained for pooled urine and serum were compared with concentrations reported for occupationally unexposed populations in recent publications.

Isotopic Variations of Zn in Biological Materials

Variations in the isotopic composition of Zn present in various biological materials were determined using high-resolution multicollector inductively coupled plasma mass spectrometry (MC-ICPMS), following digestion and purification by anion exchange chromatography. To correct for differences in instrumental mass discrimination effects between samples and standards, Cu was employed as an elemental spike. Complementary analyses of Zn separates by sector field ICPMS instruments revealed that the concentrations of the majority of potentially interfering elements were reduced to negligible levels. Residual spectral interferences resulting from (35)Cl(16)O(2)(+), (40)Ar(14)N(2)(+), and (40)Ar(14)N(16)O(+) could be instrumentally resolved from the (67)Zn, (68)Zn, and (70)Zn ion beams, respectively, during measurement by MC-ICPMS. The only other observed interference in the Cu and Zn mass range that could not be effectively eliminated by high-resolution multicollection resulted from (35)Cl(2)(+), necessitating modification of the sample preparation procedure to allow accurate (70)Zn detection. Complete duplication of the entire analytical procedure for human whole blood and hair, as well as bovine liver and muscle, provided an external reproducibility of 0.05-0.12 per thousand (2sigma) for measured delta(66/64)Zn, delta(67/64)Zn, and delta(68/64)Zn values, demonstrating the utility of the method for the precise isotopic analysis of Zn in biological materials. Relative to the selected Zn isotopic standard, delta(66/64)Zn values for biological samples varied from -0.60 per thousand in human hair to +0.56 per thousand in human whole blood, identifying the former material as the isotopically lightest Zn source found in nature to date.

Isotopic Fractionation during Diffusion of Transition Metal Ions in Solution

Isotope ratios and elemental concentrations were measured in aqueous solutions sampled at varying distances from sources of Fe or Zn ions. The measurements reveal fractionation of isotopes resulting from pure diffusion in solution. Our data demonstrate that diffusion alone can cause changes in (56)Fe/(54)Fe and (66)Zn/(64)Zn isotope ratios in excess of -0.3 per thousand. These findings thus confirm previous suspicions that transport processes contribute to observed variations in isotopic compositions. Diffusion must therefore be considered when attempting to make inferences from isotope measurements on samples originating from aqueous systems where concentration gradients may develop.

Application of double focusing sector field ICP-MS for multielemental characterization of human hair and nails. Part III. Direct analysis by laser ablation

The capabilities of laser ablation double focusing sector field inductively coupled plasma mass spectrometry for the determination of 55 elements in nails and hair were studied. Quantification was performed by external calibration using in-house matrix-matched standards in tablet form following correction for variations in ablation efficiency by internal standardization using a matrix element (S). For nails, intra-individual long- and short-term chronological variations as well as depth distribution patterns were studied. For the majority of elements tested, significant enrichment was found in the surface of the nail. Element distributions along a hair strand were investigated with a spatial resolution of 2.5 mm.

High spatial resolution analysis of ferromanganese concretions by LA-ICP-MS†

A procedure was developed for the determination of element distributions in cross-sections of ferromanganese concretions using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The effects of carrier flow rates, rf forward power, ablation energy, ablation spot size, repetition rate and number of shots per point on analyte intensity were studied. It is shown that different carrier gas flow rates are required in order to obtain maximum sensitivities for different groups of elements, thus complicating the optimisation of ICP parameters. On the contrary, LA parameters have very similar effects on almost all elements studied, thus providing a common optimum parameter set for the entire mass range. However, for selected LA parameters, the use of compromise conditions was necessary in order to compensate for relatively slow data acquisition by ICP-MS and maintain high spatial resolution without sacrificing the multielemental capabilities of the technique. Possible variations in ablation efficiency were corrected for mathematically using the sum of Fe and Mn intensities. Quantification by external calibration against matrix-matched standards was successfully used for more than 50 elements. These standards, in the form of pressed pellets (no binder), were prepared in-house using ferromanganese concentrates from a deep-sea nodule reference material as well as from shallow-marine concretions varying in size and having different proportions of three major phases: aluminosilicates, Fe- and Mn-oxyhydroxides. Element concentrations in each standard were determined by means of conventional solution nebulisation ICP-MS following acid digestion. Examples of selected inter-element correlations in distribution patterns along the cross-section of a concretion are given.

Multielemental analysis of Mn-Fe nodules by ICP-MS: optimisation of analytical method

Two acid digestion procedures (microwave-assisted and room temperature) were developed for the quantitative analysis of ferromanganese nodules by inductively coupled plasma double focusing sector field mass spectrometry (ICP-SFMS). Different compositions of the acid mixture, dilution factors and corrections for spectral interferences were tested. A combination of nitric, hydrochloric and hydrofluoric acids is necessary for complete sample digestion, with lowest acid to sample ratios (v/m) of 15 and 1.5, respectively, for the last two acids. Sample dilution factors higher than 2 x 10(4) should be used in order to decrease matrix effects and provide robust long-term instrumental operation. In spite of high dilution, method detection limits in the sub-microg g(-1) range were obtained for 54 out of 71 elements tested, due to the high detection capability of ICP-SFMS, as well as the special care taken to ensure the purity of reagents, to clean the instrument sample introduction system and to minimise sample handling. Owing to the presence of unresolved (at the resolution available) spectral interferences, accurate determination of Au, Hg, Os, Pd, Re and Rh is impossible without matrix separation. The accuracy of the entire analytical method was tested by the analysis of two nodule reference materials. The results generated agreed to within +/-2% for about 10, within +/-10% for more than 40 and within +/-20% for about 50 of 53 elements for which certified, recommended or literature values are available. A precision better than 3%, expressed as the between-digestion relative standard deviation (n = 4), was obtained for the majority of elements, except in cases limited by low analyte concentrations.

Sources of uncertainty in isotope ratio measurements by inductively coupled plasma mass spectrometry

A model is presented describing the effects of dead time and mass bias correction factor uncertainties, flicker noise, and counting statistics on isotope ratio measurement precision using inductively coupled plasma mass spectrometry (ICPMS) with a single collector. Noise spectral analysis is exploited to enable estimation of the flicker noise parameters. For the instrument used, the flicker noise component exhibited a fairly weak frequency (t) dependence (is proportional to f -0.33+/-0.12), but was directly proportional to the total number of counts, Q. As white noise, determined by counting statistics, is given by Q0.5, the isotope ratio measurement uncertainties will actually cease to improve when Q exceeds a certain threshold. This would suggest that flicker noise could become the limiting factor for the precision with which isotope ratios can be determined by ICPMS. However, under most experimental conditions, uncertainties associated with mass discrimination and dead time correction factors are decisive. For ratios up to approximately 22 (115In/113In), optimum major isotope count rates are generally below 0.3 MHz, for which precision in the mass discrimination factor is limiting. The model derived could be used as a starting point for determining optimum conditions and understanding the limitations of single-collector ICPMS for precise isotope ratio measurements.