Nickel and associated metals in New Caledonia: Exposure levels and their determinants

Reference values for metal(loid)s concentrations in the urine samples of healthy Iranian adults: Results from the first nationally representative human biomonitoring study

BACKGROUND

This study measured the concentrations of arsenic (As), aluminum (Al), cadmium (Cd), chromium (Cr), mercury (Hg), nickel (Ni), and lead (Pb) in the urine samples of the Iranian adult population.

METHODS

This nationally representative study was conducted on 490 participants in six provinces of Iran who were selected based on the clustering method. Participants included healthy Iranian adults aged above 25 years without a history of illness and non-smokers. Fasting urine sampling, body composition, and demographic measurements were performed for each participant. Urine samples were analyzed by acid digesting method using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The analysis included descriptive statistics and multiple linear regression using Python programming language.

RESULTS

The geometrical mean (with corresponding reference values, µg/l) concentrations of metal(loid)s in urine for women, men, and both were 198.2 (625.3), 163.5 (486.1), and 192.5(570.4) for Al, 15.6(51.7), 28.8(71.1), and 21.9 (61.64) for As, 18.5(55.2), 20.7(56.5), and 19.22(55.75) for Pb, 17.9(57.6), 17.9 (53.9), and 17.9(56) for Ni, 13.95(47.5), 20.3(62.2) and 16(51.6) for Cr, 3.5(12.2), 2.9(11.5), and 3.3(12) for Hg, 0.74(2.7), 0.95 (3.6), and 0.81(3.1) for Cd. There was a direct relationship between the concentration of metal(loid)s and demographic indicators and body composition (P<0.05). Moreover, there was a direct relationship between the concentration of As, Cr, Hg, Ni, and Pb with age and wealth index (P<0.05).

CONCLUSIONS

The concentrations found could be used as the reference range for As, Al, Cd, Cr, Hg, Ni, and Pb for human biomonitoring studies on the Iranian adult population.

Identification of core carcinogenic elements based on the age-standardized mortality rate of lung cancer in Xuanwei Formation coal in China

In this study, the core carcinogenic elements in Xuanwei Formation coal were identified. Thirty-one samples were collected based on the age-standardized mortality rate (ASMR) of lung cancer; Si, V, Cr, Co, Ni, As, Mo, Cd, Sb, Pb, and rare earth elements and yttrium (REYs) were analyzed and compared; multivariate statistical analyses (CA, PCA, and FDA) were performed; and comprehensive identification was carried out by combining multivariate statistical analyses with toxicology and mineralogy. The final results indicated that (1) the high-concentration Si, Ni, V, Cr, Co, and Cd in coal may have some potential carcinogenic risk. (2) The concentrations of Cr, Ni, As, Mo, Cd, and Pb meet the zoning characteristics of the ASMR, while the Si concentration is not completely consistent. (3) The REY distribution pattern in Longtan Formation coal is lower than that in Xuanwei Formation coal, indicating that the materials of these elements in coal are different. (5) The heatmap divides the sampling sites into two clusters and subtypes in accordance with carcinogenic zoning based on the ASMR. (6) PC1, PC2, and PC3 explain 62.629% of the total variance, identifying Co, Ni, As, Cd, Mo, Cr, and V. (7) Fisher discriminant analysis identifies Ni, Si, Cd, As, and Co based on the discriminant function. (8) Comprehensive identification reveals that Ni is the primary carcinogenic element, followed by Co, Cd, and Si in combination with toxicology. (9) The paragenesis of Si (nanoquartz), Ni, Co, and Cd is an interesting finding. In other words, carcinogenic elements Ni, Co, Cd, and Si and their paragenetic properties should receive more attention.

Tracing nickel smelter emissions using European honey bees

This study investigated trace element contamination in honey bees inhabiting urban areas around the South Pacific's largest and longest operating nickel smelter in Nouméa, New Caledonia. There remains a paucity of research on the environmental impact of nickel smelting, and to date, there has been no assessment of its effects on the popular practice of beekeeping, or whether honey bees are a suitable tracer for nickel smelting emissions. Honey bees and honey were sampled from 15 hives across Nouméa to ascertain linkages between nickel smelter emissions, environmental contamination, and trace element uptake by bees. Comparison of washed and unwashed bees revealed no significant difference in trace element concentrations, indicating trace elements bioaccumulate within the internal tissues of bees over time. Accordingly, trace element concentrations were higher in dead bees than those that were sampled live, with smelter related elements chromium, cobalt and nickel being significantly different at p < 0.05. Except for boron, trace element concentrations were consistently higher in bees than in honey, suggesting that the transfer of trace elements from bees during honey production is negligible. Elevated concentrations of potentially toxic trace elements including cobalt, chromium and nickel in bees declined with distance from smelting operations (Spearman's Rho, p < 0.05), indicating the relationship between environmental contamination and the uptake of trace elements by bees. The findings of this study emphasise potential environmental and human health risks associated with trace element contamination from nickel smelting operations and affirm the use of honey bees as a biomonitor of potentially harmful nickel smelting emissions.

Association of urinary nickel levels with diabetes and fasting blood glucose levels: A nationwide Chinese population-based study

Some epidemiological studies support a relationship between nickel exposure and diabetes in the general population. To address this, we tested the association of nickel exposure with diabetes in 10,890 adults aged ≥ 18 years old from the China National Human Biomonitoring study conducted in 2017-2018. Urinary nickel concentrations and fasting blood glucose (FBG) were measured, and lifestyle and demographic data were collected. Weighted logistic and linear regressions were used to estimate the associations of urinary nickel levels with diabetes prevalence and FBG. Restricted cubic splines (RCS) were used to test for the dose-response relationship. The odd ratio (95% confidence interval [CI]) of diabetes for the highest versus lowest quartiles of urinary nickel concentrations was 1.74 (1.28, 2.36) in the multivariate model (p _trend =0.001). Each one-unit increase in log-transformed urinary nickel concentrations was associated with a 0.36 (0.17, 0.55) mmol/L elevation in FBG. The RCS curves showed a monotonically increasing dose-response relationship of urinary nickel with diabetes as well as FBG levels, and then tended to flatten after about 4.75 μg/L of nickel exposure. The nickel-diabetes association was stronger in individuals with lower than those with higher rice consumption (OR: 2.39 vs. 1.72). Our study supports a positive association between nickel exposure and diabetes prevalence in Chinese adults, especially in individuals with lower rice consumption. Further large-scale prospective studies are needed to validate our findings.

Urinary metals as influencing factors of coronary heart disease among a population in Guangzhou, China

The cardiovascular system is highly sensitive to toxic metal exposure and trace element dysregulation. However, previous findings relating to metal exposure and coronary heart disease (CHD) have partially been conflicting and difficult to exhibit the combined effect of metal mixtures. This case-control study investigated urinary concentrations of ten metal/metalloids among clinically-diagnosed CHD patients and healthy adults during May to December 2021 in Guangzhou, China. We found that cadmium (Cd) status in urine from CHD patients was remarkably higher than its reference, while chromium (Cr), nickel (Ni), copper (Cu) and selenium (Se) concentrations were lower (p < 0.05). Spearman correlation analysis showed that urinary arsenic (As) and Se were highly correlated (r_s=0.830, p < 0.001), indicating their similar sources. Principal component analysis (PCA) exhibited denser distribution of Cd-Sn in cases than in controls. Logistic regression analysis exhibited significant associations between urinary Cd (adjusted OR: 1.965, 95% CI: 1.222-3.162), Se (0.787, 95% CI: 0.695-0.893), Ni (0.493, 95% CI: 0.265-0.916) and CHD risk. Quantile g-computation showed negative joint effect of metal mixtures on CHD (adjusted OR: 0.383, 95% CI: 0.159-0.932) (p < 0.05), suggesting the need for supplementing essential trace elements. The negative partial effect was primarily attributed to Se and Ni, while positive partial effect was mainly due to tin (Sn) and Cd. Nevertheless, we also found a quantile increase of Cd-Sn level was negatively correlated with 8.26% (95% CI: 3.44-13.08%) decrease of high-density lipoprotein cholesterol (p < 0.001), and 71.2% of the joint effect attributed to Cd. Based on random forest, Se, Cd and Ni were found to be the dominant influencing factors of CHD. The role of Ni in CHD is yet to be uncovered, while excessive Cd exposure and low Se status among CHD patients need to be mitigated.

NiONP-Induced Oxidative Stress and Mitochondrial Impairment in an In Vitro Pulmonary Vascular Cell Model Mimicking Endothelial Dysfunction

The development and use of nanomaterials, especially of nickel oxide nanoparticles (NiONPs), is expected to provide many benefits but also has raised concerns about the potential human health risks. Inhaled NPs are known to exert deleterious cardiovascular side effects, including pulmonary hypertension. Consequently, patients with pulmonary hypertension (PH) could be at increased risk for morbidity. The objective of this study was to compare the toxic effects of NiONPs on human pulmonary artery endothelial cells (HPAEC) under physiological and pathological conditions. The study was conducted with an in vitro model mimicking the endothelial dysfunction observed in PH. HPAEC were cultured under physiological (static and normoxic) or pathological (20% cycle stretch and hypoxia) conditions and exposed to NiONPs (0.5–5 μg/cm²) for 4 or 24 h. The following endpoints were studied: (i) ROS production using CM-H₂DCF-DA and MitoSOX probes, (ii) nitrite production by the Griess reaction, (iii) IL-6 secretion by ELISA, (iv) calcium signaling with a Fluo-4 AM probe, and (v) mitochondrial dysfunction with TMRM and MitoTracker probes. Our results evidenced that under pathological conditions, ROS and nitrite production, IL-6 secretions, calcium signaling, and mitochondria alterations increased compared to physiological conditions. Human exposure to NiONPs may be associated with adverse effects in vulnerable populations with cardiovascular risks.

Urinary Metals as a Marker of Exposure in Men and Women in the Welding and Electrical Trades: A Canadian Cohort Study

OBJECTIVES

Men and women working in the welding trades undergo the same apprenticeship training but it is unknown whether, once in the trade, their exposures differ. Comparison of urinary metal concentrations, having adjusted for estimated airborne exposure, may provide an answer.

METHODS

Men and women were recruited to a cohort study of workers in the welding and electrical trades (the Workers Health in Apprenticeship Trades-Metal working and Electrical [WHAT-ME study]). They completed a recruitment questionnaire and further questionnaires every 6 months for up to 5 years. At each follow-up, they gave details on employment and, if welding, answered trade-specific questionnaires. Urine samples were collected by mail. Welding exposure matrices were developed to estimate metal exposures from welding process, base metal, and consumables. Urinary metal concentrations, determined by ICP-MS, were compared by trade (welding or electrical). Within welding, the relation of urinary concentrations to estimated airborne exposure was examined, with adjustment for potential confounders including sex, use of respiratory protective equipment (RPE), and time spent outdoors. Natural logarithms were taken of exposure estimates and urinary concentrations, to reduce skew. All regression analyses included creatinine concentration.

RESULTS

Urinary metal concentrations were analysed for 12 metals in 794 samples. Antimony, arsenic, lead, and mercury had a high proportion of samples with no metal detected and were not considered further. The urinary concentrations of aluminum, cadmium, chromium, cobalt, copper, manganese, nickel, and zinc were compared for welders (434 samples) and electrical workers (360). After adjustment for potential confounders, welders had higher urinary concentrations for aluminum (β = 0.13 95%CI 0.03-0.24) and chromium (β = 0.66 95%CI 0.55-0.77). Of 434 welder urines, 334 could be matched securely to detailed information about the most recent day welding. For these, an estimate of airborne exposure was made for aluminum, chromium, manganese, and nickel. Male welders were estimated to have higher airborne exposure to chromium and nickel than women welders. No difference was seen in the estimated exposures for aluminum or manganese (or total dust). Regression analyses of the relation of urinary metals to estimated exposure showed a good concordance for aluminum (β = 0.09 95%CI 0.04-0.15 (P < 0.001) and chromium (β = 0.11 95%CI 0.05-0.17 P < 0.001). The concordance for manganese and nickel was positive, but much weaker. Urinary concentrations of aluminum and nickel were somewhat lower with increasing time wearing RPE and, for chromium and nickel, with time working outdoors. Having adjusted for estimated exposure, creatinine and other confounders, male welders had lower urine concentrations of aluminum (β = -0.35 95%CI -0.51 to -0.19 P < 0.001) chromium (β = -0.38 95%CI -0.57 to -0.19 P < 0.001) and manganese (β = -0.36 95%CI -0.49 to -0.23 P < 0.001) than female welders.

CONCLUSION

Welders had higher urinary concentrations of aluminum and chromium than electrical workers. Exposure estimates of aluminum and chromium for welders were a valid representation of the airborne exposures to these metals. Although male welders were estimated to have higher exposures of chrome and nickel than female welders, the higher urinary metal concentrations in women welders is of concern, particularly for women who may conceive while in the trade.

Biosorption of nickel ions Ni2+ by natural and modified Pinus caribaea Morelet sawdust

The potential of Pinus caribaea Morelet sawdust for the removal of nickel ions (Ni²⁺) and other metallic trace ions (Co²⁺, Cr³⁺, Mn²⁺) from aqueous solutions was investigated under batch conditions. Several parameters such as size of particles, contact time, pH, initial metal and biomass concentrations, desorption conditions and reusability were evaluated on natural biomass. Biosorption was fast, effective (73%) and biomaterial can be reused after five cycles. To enhance the removal capacity of nickel, pine sawdust was modified by acidic and oxidative treatments. Cellulosic residues from sawdust sequential extraction showed great biosorption capacity (96%). In the presence of a metal mixture, oxidized sawdust had better selectivity for Cr³⁺ ions than for Ni²⁺. Pinus caribaea biomass could be an environmental, inexpensive and renewable material for the depollution of water laden with metallic trace elements.

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Pinus caribaea sawdust is an effective biosorbent of metallic trace elements.

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High Ni²⁺ removal efficiency was observed at pH 8 with 5 g/L of biosorbent.

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Equilibrium adsorption was described by Freundlich and Langmuir isotherms.

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Pine sawdust is a reusable biosorbent with good desorption capacity.

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Efficiency of acidified and oxidized adsorbents.

Biological monitoring of exposure to rare earth elements and selected metals in the Inuit population of Nunavik, Canada

In Nunavik (Northern Quebec, Canada), some mining projects are envisioned, that could increase the contamination of the environment by various chemicals, including rare earth elements (REEs), and implicitly Inuit population exposure. The objective of this study was to determine the baseline biological exposure of the population to these elements, before the potential mining development occurs. In the framework of the 2017 Qanuilirpitaa? Inuit health survey, urine samples were obtained from a representative sample of the adult Nunavik population, which were used to constitute 30 pooled samples according to age, sex and Nunavik subregions. Pooled samples were analyzed using sensitive and accurate methods involving ICP-MS platforms to quantify urinary concentrations of 17 REEs and 7 elements of interest in Nunavik (arsenic, antimony, chromium, cobalt, nickel, thallium and uranium). REEs were mostly not detected in pooled samples from this population. Detectable concentrations were found in some samples for cerium (range: 0.5-0.7 nmol/L; 27% > method detection limit (MDL) and lanthanum (range: 0.2-0.4 nmol/L; 33% > MDL). As for the other elements of interest, antimony, arsenic, cobalt and thallium were detected in 100% of the samples, whereas chromium and nickel were detected in 83% and 80% of the samples, respectively. Concentrations of arsenic (geometric mean (GM) = 0.5 μmol/L) and cobalt (GM = 5.2 nmol/L) were greater than in the general Canadian population; the opposite was observed for nickel (GM = 8.9 nmol/L). Arsenic concentrations increased significantly with age, whereas the opposite trend was observed for nickel and thallium. In this first biomonitoring study focusing on REEs and carried out in a representative sample of the Nunavik population, we found no evidence of significant exposure from pooled samples analysis. These results could eventually be used as baseline values in future studies aiming to assess temporal trends of exposure to REEs.

NiONPs-induced alteration in calcium signaling and mitochondrial function in pulmonary artery endothelial cells involves oxidative stress and TRPV4 channels disruption

In New Caledonia, anthropic activities, such as mining, increase the natural erosion of soils in nickel mines, which in turn, releases nickel oxide nanoparticles (NiONPs) into the atmosphere. Pulmonary vascular endothelial cells represent one of the primary targets for inhaled nanoparticles. The objective of this in vitro study was to assess the cytotoxic effects of NiONPs on human pulmonary artery endothelial cells (HPAEC). Special attention will be given to the level of oxidative stress and calcium signaling, which are involved in the physiopathology of cardiovascular diseases. HPAEC were exposed to NiONPs (0.5-150 μg/cm²) for 4 or 24 h. The following different endpoints were studied: (i) ROS production using CM-H₂DCF-DA probe, electron spin resonance, and MitoSOX probe; the SOD activity was also measured (ii) calcium signaling with Fluo4-AM, Rhod-2, and Fluo4-FF probes; (iii) inflammation by IL-6 production and secretion and, (iv) mitochondrial dysfunction and apoptosis with TMRM and MitoTracker probes, and AnnexinV/PI. Our results have evidenced that NiONPs induced oxidative stress in HPAEC. This was demonstrated by an increase in ROS production and a decrease in SOD activity, the two mechanisms seem to trigger a pro-inflammatory response with IL-6 secretion. In addition, NiONPs exposure altered calcium homeostasis inducing an increased cytosolic calcium concentration ([Ca²⁺]_i) that was significantly reduced by the extracellular calcium chelator EGTA and the TRPV4 inhibitor HC-067047. Interestingly, exposure to NiONPs also altered TRPV4 activity. Finally, HPAEC exposure to NiONPs increased intracellular levels of both ROS and calcium ([Ca²⁺]_m) in mitochondria, leading to mitochondrial dysfunction and HPAEC apoptosis.

International Analysis of Sources and Human Health Risk Associated with Trace Metal Contaminants in Residential Indoor Dust

People spend increasing amounts of time at home, yet the indoor home environment remains understudied in terms of potential exposure to toxic trace metals. We evaluated trace metal (and metalloid) concentrations (As, Cu, Cr, Mn, Ni, Pb, and Zn) and health risks in indoor dust from homes from 35 countries, along with a suite of potentially contributory residential characteristics. The objective was to determine trace metal source inputs and home environment conditions associated with increasing exposure risk across a range of international communities. For all countries, enrichments compared to global crustal values were Zn > Pb > Cu > As > Cr > Ni; with the greatest health risk from Cr, followed by As > Pb > Mn > Cu > Ni > Zn. Three main indoor dust sources were identified, with a Pb-Zn-As factor related to legacy Pb sources, a Zn-Cu factor reflecting building materials, and a Mn factor indicative of natural soil sources. Increasing home age was associated with greater Pb and As concentrations (5.0 and 0.48 mg/kg per year of home age, respectively), as were peeling paint and garden access. Therefore, these factors form important considerations for the development of evidence-based management strategies to reduce potential risks posed by indoor house dust. Recent findings indicate neurocognitive effects from low concentrations of metal exposures; hence, an understanding of the home exposome is vital.

Trace element contamination of soil and dust by a New Caledonian ferronickel smelter: Dispersal, enrichment, and human health risk

Metallurgical industries remain a considerable source of trace element contamination and potential human health risk. Determination of sources is a key challenge. With respect to the South Pacific's largest and longest operating metallurgic smelter in Nouméa, New Caledonia, determining the environmental impact and subsequent human health risk associated with local ferronickel smelting is complicated by natural geological enrichment of Ni and Cr. This study applies a multi-method and multi-matrix approach to disentangle smelter emissions from geogenic sources and model the consequent health risk from industrial activity. Dust wipes (n = 108), roadside soil (n = 91), garden soil (n = 15) and household vacuum dust (n = 39) were assessed to explore geospatial trace element (As, Cr, Cu, Fe, Mn, Ni, Pb, S, V and Zn) variations across outdoor and indoor environments. Enrichment factors (EF) identified elevated levels of smelter-related trace elements: S (EF = 7), Ni (EF = 6) and Cr (EF = 4), as well as Zn (EF = 4). Smelter-related elements in soil and dust deposits were negatively correlated with distance from the facility. Similarity of Pb isotopic compositions between dust wipes, surface soil and vacuum dust indicated that potentially toxic trace elements are being tracked into homes. Non-carcinogenic health risk modelling (Hazard Index, HI) based on 15 spatial nodes across Nouméa revealed widespread exceedance of tolerable risk for children (0-2 years) for Ni (HI 1.3-15.8) and Mn (HI 0.6-1.8). Risk was greatest near the smelter and to the north-west, in the direction of prevailing wind. Given the elevated cancer risk documented in New Caledonia, disentanglement of environmental from industrial sources warrants further attention to ensure community health protection. Our analysis illustrates how the confounding effects from complex environmental factors can be distilled to improve the accuracy of point source apportionment to direct future mitigation strategies.

Development of a bioavailability-based risk assessment framework for nickel in Southeast Asia and Melanesia

Nickel laterite ore deposits are becoming increasingly important sources of Ni for the global marketplace and are found mainly in tropical and subtropical regions, including Indonesia, the Philippines, Papua New Guinea, Cuba, and New Caledonia. There are few legislatively derived standards or guidelines for the protection of aquatic life for Ni in many of these tropical regions, and bioavailability-based environmental risk assessment (ERA) approaches for metals have mainly been developed and tested in temperate regions, such as the United States and Europe. This paper reports on a multi-institutional, 5-y testing program to evaluate Ni exposure, effects, and risk characterization in the Southeast Asia and Melanesia (SEAM) region, which includes New Caledonia, Papua New Guinea, the Philippines, and Indonesia. Further, we have developed an approach to determine if the individual components of classical ERA, including effects assessments, exposure assessments, and risk characterization methodologies (which include bioavailability normalization), are applicable in this region. A main conclusion of this research program is that although ecosystems and exposures may be different in tropical systems, ERA paradigms are constant. A large chronic ecotoxicity data set for Ni is now available for tropical species, and the data developed suggest that tropical ecosystems are not uniquely sensitive to Ni exposure; hence, scientific support exists for combining tropical and temperate data sets to develop tropical environmental quality standards (EQSs). The generic tropical database and tropical exposure scenarios generated can be used as a starting point to examine the unique biotic and abiotic characteristics of specific tropical ecosystems in the SEAM region. Integr Environ Assess Manag 2021;17:802-813. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Ultramafic geoecosystems as a natural source of Ni, Cr, and Co to the environment: A review

Ultramafic soils are in equal parts fascinating and dangerous. Developed on rocks derived predominately from the Earth's mantle and metamorphosed at the ocean floors, ultramafic soils form in the places where tectonic forces brought these rocks from mantle depths to the surface. As it is common in nature, both ultramafic rocks and soils are site-specific, and vary in character and composition; however, they have one thing in common, they are enriched in certain elements and three metals in particular form an "ultramafic" triad: Ni, Cr, and Co. These three metals are far from being human-friendly and strict legislative limits are established for maximum allowable concentrations of these metals in soils, but mostly in the case when the metals are of anthropogenic origin. However, ultramafic soils are a natural phenomenon where increased metal content is not the result of pollution, but rather referred as a peculiar geochemical background, therefore there is no reason for their remediation. At the same time, it is not that easy to actually find an ultramafic soil that does not overstep the limits (for the sake of this paper we use median world Regulatory Guidance Values - RGVs). Often, mobile Ni and Co concentrations are above the guidelines when doing tests to estimate the bioavailable fraction (EDTA and DTPA), and high concentrations of Ni are also commonly present in excluder plants (also edible ones). Also waters in ultramafic areas often exceed Ni and Cr(VI) limits. It is therefore expected that the ultramafic metals are present in the food chain and they might constitute a potential health risk. Thus, there is a need for additional research focused on assessment of the potential health consequences of chronic high exposure on naturally occurring Ni, Cr, and Co.

Nickel spreading assessment in New Caledonia by lichen biomonitoring coupled to air mass history

Lichen biomonitoring and air mass trajectories were used to study the influence of mining activities in the atmospheric dispersion of metallic elements to assess the exposure of the population to dust emitted by mining activities. A map of forward trajectory densities from open mine surfaces throughout New Caledonia was computed and allowed to identify three preferred wind directions (trade wind, bent trade winds and oceanic winds) that could arise in mining particles dispersion all over New Caledonia. Areas where an air quality monitoring would be advisable to evaluate the exposure of the population to the Nickel dusts have been identified. Lichens collected around the industrial mining site KNS and in North Provence of New Caledonia were analysed for their Ni, Co, Cr, Zn and Ti contents. Backward trajectories were simulated from the lichen sampling point using FLEXTRA fed with ECMWF meteorological data, and densities of trajectories having overflown a mine were calculated. Ratio metal/Ti was then plotted as a function of air mass trajectory densities having overflown open pits. A positive correlation between trajectory densities and titanium-normalized metal in lichen for Ni, Co, Cr was highlighted, indicating that mining is a source of dispersion of these metals. For Zn, which is a tracer of fossil fuel or biomass (wood) combustion activity, no correlation was found. Graphical abstract.

Measurement of urinary cobalt as its complex with 2-(5-chloro-2-pyridylazo)-5-diethylaminophenol by liquid chromatography-tandem mass spectrometry for the purpose of anti-doping control

Cobalt is well known for its ability to stimulate erythropoiesis via stabilization of hypoxia-inducible factors. In sports, this can provide a competitive benefit to athletes, so the World Anti-Doping Agency prohibits the use of cobalt in any form except its cobalamin vitamers. As of now, cobalt in biological fluids is detected by inductively coupled plasma mass spectrometry (ICP-MS), a technique which has very limited availability in anti-doping laboratories. Therefore, a quantitative method based on liquid chromatography-tandem mass spectrometry capable of measuring urinary cobalt in the form of its complex with 2-(5-chloro-2-pyridylazo)-5-diethylaminophenol (5-Cl-PADAP) has been developed and validated. A cobalt complex with deuterium-labeled 5-Cl-PADAP was used as internal standard. The method was found linear over the concentration range of 5-500 ng/ml with a combined standard uncertainty less than 10% at 15, 200, and 450 ng/ml. Stability of cobalt ions in urine was investigated over the course of 2 months; the concentration of free Co²⁺ was observed to decline by approximately 50% but restored upon hydrolysis with hydrochloric acid. Unlike ICP-MS, this method is practically unaffected by the presence of cyanocobalamin as the latter is resistant to acid hydrolysis. Notwithstanding the lack of formalized threshold concentration of cobalt in urine, it is highly desirable that more anti-doping laboratories engage in testing for cobalt levels to better understand the prevalence of cobalt misuse in athletes. Given that cobalt salts are inexpensive and easily obtainable, the risk of such abuse should not be underestimated.

Human impacts recorded in chemical and isotopic fingerprints of soils from Dunedin City, New Zealand

We present results from the first urban chemical and isotopic soil baseline survey to be completed for a New Zealand city. The major, minor, trace and isotopic composition of soils from different depths across the city of Dunedin are shown to be spatially variable due to geogenic and anthropogenic influences. Based on Principal component analysis (PCA) for the shallow soil depth, at least 40% (PC1 and PC3) of the dataset variance is attributed to a geogenic source. Soils enriched in Al, Cr, Fe, Hf, Mo, Ni, Th, Ti, U, V and Zr (PC1) are spatially associated with mapped units of the basaltic Dunedin Volcanic Group, indicating a geogenic source. An anthropogenic influence is attributed to at least 23% (PC2 and PC5) of the dataset variance. The chemical elements As, B, Bi, Cd, Cu, P, Pb, Sb, Sn and Zn (PC2) are strongly spatially associated with soils sampled above high-density urban residential, commercial and industrial sites, and are interpreted to reflect heavy metal contamination from human activities. In conjunction with historical vehicle emissions from leaded petrol, we suggest that legacy leaded paint from residential, commercial and industrial buildings flaking into Dunedin City soils is a significant contributor to Pb in the Dunedin urban environment. Median heavy metal contents for shallow soils (0-2 cm) from a variety of land-uses throughout Dunedin City are shown to be almost an order of magnitude greater than median heavy metal concentrations in soils from regional baselines. Significantly, urban anthropogenic sources of heavy metals, and C, N and S isotopes are shown to exert a stronger influence on soil composition than rural anthropogenic sources. Results from this study provide an important case-study for urban soil contamination for a relatively young city from the Southern Hemisphere, for which there are currently few examples.

Concentration decline in response to source shift of trace metals in Elbe River, Germany: A long-term trend analysis during 1998-2016

Monitoring spatial and temporal chemical status of water bodies is crucial to assist environmental policy, identify the chemical fingerprints, and further reduce the source orientated pollutants. Elbe River is one of the major rivers affected by anthropogenic activities in vicinity countries. This study assessed the spatiotemporal changes in response to source shift of Cd, Cu, Ni, Pb, and Zn in the suspended particulate matter (SPM) at upstream, midstream, and downstream of the Elbe River reach in Saxony state, Germany. The average contents of trace metals in SPM was found in the order of Zn (676 mg/kg) » Pb (79 mg/kg) > Cu (74 mg/kg) > Ni (48 mg/kg) » Cd (3.2 mg/kg). According to the Mann-Kendall trend test, Cd, Cu, Pb, and Zn showed significant declines over 1998-2016. The results of source apportionment indicate industrial, urban, natural, and historical mining sources influencing the metal contents in the Elbe River of Saxony. The contributions of industrial and urban pollution decreased by 58.2% from 1998 to 2007 to 2008-2016. The contribution of the natural source was steady over the last two decades.