Recent advances in analysis of trace elements in environmental samples by X-ray based techniques (IUPAC Technical Report)

Environmental health science research: opportunities and challenges for some developing countries in Africa

Due to ongoing developmental projects, there is a need for regular monitoring of the impact of pollutants on the environment. This review documented the challenges and opportunities in the field of environmental health sciences in some African countries. A systematic review was used to investigate opportunities and challenges in the field of environmental health science in Africa by examining published work with a specific focus on Africa. The reports showed that funding and infrastructure as the major problems. The study also highlighted recruiting study participants, retention, and compensation as a bane in the field in Africa. The absence of modern equipment also hinders research. The review, however, noted research collaboration from the region including studies on emerging pollutants such as pharmaceuticals, per and polyfluoroalkyl substances (PFAS), and microplastic (MPs) as great opportunities. The study concluded that collaboration with other continents, exchange programs and improved governmental interventions may help.

Quantification of [99Tc]TcO4- in urine by means of anion-exchange chromatography-aerosol desolvation nebulization-inductively coupled plasma-mass spectrometry

To sensitively determine 99Tc, a new method for internal quantification of its most common and stable species, [99Tc]Tc O 4 - , was developed. Anion-exchange chromatography (IC) was coupled to inductively coupled plasma-mass spectrometry (ICP-MS) and equipped with an aerosol desolvation system to provide enhanced detection power. Due to a lack of commercial Tc standards, an isotope dilution-like approach using a Ru spike and called isobaric dilution analysis (IBDA) was used for internal quantification of 99Tc. This approach required knowledge of the sensitivities of 99Ru and 99Tc in ICP-MS. The latter was determined using an in-house prepared standard manufactured from decayed medical 99mTc-generator eluates. This standard was cleaned and preconcentrated using extraction chromatography with TEVA resin and quantified via total reflection X-ray fluorescence (TXRF) analysis. IC coupled to ICP-MS enabled to separate, detect and quantify [99Tc]Tc O 4 - as most stable Tc species in complex environments, which was demonstrated in a proof of concept. We quantified this species in untreated and undiluted raw urine collected from a patient, who previously underwent scintigraphy with a 99mTc-tracer, and determined a concentration of 19.6 ± 0.5 ng L-1. The developed method has a high utility to characterize a range of Tc-based radiopharmaceuticals, to determine concentrations, purity, and degradation products in complex samples without the need to assess activity parameters of 99(m)Tc.

Changes in chemical fractionation of copper and zinc in soil as a function of incubation moisture content and organic matter amendments

Copper and zinc are essential micronutrients that are potentially toxic when present in excess in soils. Their bioavailability depends on their speciation in soil, but this may vary with environmental conditions. Aeration and hence redox conditions, and organic matter amendments are among the factors likely to cause variation on metal fractionation. We have monitored the chemical fractionation of both native and added copper and zinc in a clay loam top soil during a 5-month laboratory incubation. The effects of aeration (moist soil or flooded) and addition of two organic matter amendments, alfalfa straw or leaf compost, were studied. Metal spike was more labile than legacy metal, and was slowly redistributed over the incubation period. Organic matter caused short-lived flushes of metals, attributed to metal chelation with soluble organic matter. This effect was greater for straw than for more stable compost. There was no evidence that added organic matter increased the capacity of soil organic matter to immobilise metal. Flooding solubilized soil metal (hydr)oxides, releasing legacy Cu and Zn, but with less effect on the capacity to immobilise metal spike. Effects of flooding and organic matter addition were not additive. Both metals appear to be precipitated as sulphides under reducing conditions, and accounted for in the acid soluble phase. Monitoring the dynamics of metal distribution gives a more comprehensive understanding of underlying processes than would a single measurement, and is closer to in campo conditions than slurry microcosms.

Suitability and Applications of Total-Reflection X-Ray Fluorescence Spectrometry for Analytical Characterization of Nuclear Materials

The suitability and applications of Total reflection X-ray Fluorescence (TXRF) for characterization of nuclear materials are numerous. TXRF has been successfully applied for trace, minor and major determinations of constituents in nuclear materials such as fuel, clad, control rod, coolant, etc. The two major advantages of TXRF i.e. requirement of very small sample for analysis and non-requirement of matrix matched standards, make this technique further more attractive and suitable for nuclear industry. The applications of TXRF for trace analysis in nuclear materials such as fuel, clad, coolant and control rods are described in detail along with its applications for determination of major and speciation studies in TXRF mode.

Elucidating uranium interactions with synthetic Na-P1 zeolite/Ca2+-substituted alginate composite granules through batch and spectroscopic studies: Emphasizing the significance of ion exchange and complexation

Uranium, a key member of the actinides series, is radioactive and may cause severe environmental hazards once discharged into the water due to high toxicity. Removal of uranium via adsorption by applying tailored, functional adsorbents is at the forefront of tackling such pollution. Here, we report the optimized functionalization of the powder coal fly-ash (CFA) derived Na-P1 synthetic zeolite to the form of granules by employing the biodegradable polymer-calcium alginate (CA) and their application to remove aqueous U. The optimized synthesis showed that granules are formed at the CA concentration equals to 0.5 % wt., and that application of 1% wt. solution renders the most effective U scavengers. The maximum U adsorption capacity (qmax) increases significantly after CA modification from 44.48 mgU/g for native, powder Na-P1 zeolite to 62.53 mg U/g and 76.70 mg U/g for 0.5 % wt. and 1 % wt. CA respectively. The U adsorption follows the Radlich-Peterson isotherm model, being the highest at acidic pH (pHeq∼4). The U adsorption kinetics reveals swift U uptake, reaching equilibrium after 2h for 1 % ZACB and 3 h for 0.5 % wt. ZACB following the pseudo-second-order (PSO) kinetic model. SEM-EDXS investigation elucidates that adsorbed U occurs onto materials as an inhomogenous, well-dispersed, and micrometer-scale aggregate. Further, XPS and μ-XRF spectroscopies complementarily confirmed the hexavalent oxidation state of adsorbed U and its altered distribution on ZACBs with varying CA concentrations. U distribution was probed "in-situ" onto materials while correlations between the major elements (Al, Si, Ca, U) contributing to U scavenging were calculated and compared. Finally, a real-life coal mine wastewater (CMW) polluted by 238U and 228,226Ra was successfully purified, satisfying WHO guidelines after treatment using ZACBs. These findings offer new insights on successful yet optimized Na-P1 zeolite modification using biodegradable polymer (Ca2+-exchanged alginate) aimed at efficient U removal, displaying a near-zero environmental impact.

Combining micro- and portable-XRF as a tool for fast identification of virus infections in plants: The case study of ASa-Virus in Fraxinus ornus L

Plant viruses can affect micro- and macro-nutrients homeostasis in woody plants, with fluctuation in the concentration of some elements at the leaf level due to the pathogen activity and/or the plant physiological response to the infection.Leaves of Fraxinus ornus L. (flowering ash) were sampled for three consecutive years in the city of Hamburg (Germany), from both trees showing the typical symptoms of the ash shoestring associated virus infection (ASaV+) and healthy trees (ASaV-). Such leaves were analyzed by μ-XRF, using both laboratory and synchrotron X-ray sources, and large differences between symptomatic and not symptomatic leaves were observed: ASaV+ samples showed uneven element distribution and regions of the lamina with severe depletions of P, S, and Ca. Differently, K appeared more concentrated. Thus, 139 leaflets sampled from various healthy and infected ash trees over the three-year period were analyzed for K and Ca concentration with a portable XRF instrument. We found that the K:Ca concentration ratio was always significantly higher in ASaV+ samples, and this trend was verified for all the samplings over the tree years. We conclude that the K:Ca ratio parameter has potential in the frame of trendsetting diagnostics and could be used, together with visual symptoms, for a rapid, non-destructive, on-site and cheap indirect ASaV detection.

Trace-element XAFS sensitivity: a stress test for a new XRF multi-detector

X-ray absorption fine-structure (XAFS) spectroscopy can assess the chemical speciation of the elements providing their coordination and oxidation state, information generally hidden to other techniques. In the case of trace elements, achieving a good quality XAFS signal poses several challenges, as it requires high photon flux, counting statistics and detector linearity. Here, a new multi-element X-ray fluorescence detector is presented, specifically designed to probe the chemical speciation of trace 3d elements down to the p.p.m. range. The potentialities of the detector are presented through a case study: the speciation of ultra-diluted elements (Fe, Mn and Cr) in geological rocks from a calcareous formation related to the dispersal processes from Ontong (Java) volcanism (mid-Cretaceous). Trace-elements speciation is crucial in evaluating the impact of geogenic and anthropogenic harmful metals on the environment, and to evaluate the risks to human health and ecosystems. These results show that the new detector is suitable for collecting spectra of 3d elements in trace amounts in a calcareous matrix. The data quality is high enough that quantitative data analysis could be performed to determine their chemical speciation.

Vocabulary of radioanalytical methods (IUPAC Recommendations 2020)

These recommendations are a vocabulary of basic radioanalytical terms which are relevant to radioanalysis, nuclear analysis and related techniques. Radioanalytical methods consider all nuclear-related techniques for the characterization of materials where ‘characterization’ refers to compositional (in terms of the identity and quantity of specified elements, nuclides, and their chemical species) and structural (in terms of location, dislocation, etc. of specified elements, nuclides, and their species) analyses, involving nuclear processes (nuclear reactions, nuclear radiations, etc.), nuclear techniques (reactors, accelerators, radiation detectors, etc.), and nuclear effects (hyperfine interactions, etc.). In the present compilation, basic radioanalytical terms are included which are relevant to radioanalysis, nuclear analysis and related techniques.

Assessing chromium pollution and natural stabilization processes in agricultural soils by bulk and micro X-ray analyses

A combined approach based on multiple X-ray analytical techniques and conventional methods was adopted to investigate the distribution and speciation of Cr in a polluted agricultural soil, from the bulk-scale down to the (sub)micro-level. Soil samples were collected from two different points, together with a control sample taken from a nearby unpolluted site. The bulk characterization revealed that the polluted soils contained much higher concentrations of organic matter (OM) and potentially toxic elements (PTE) than the control. Chromium was the most abundant PTE (up to 5160 g kg^-1), and was present only as Cr(III), as its oxidation to Cr(VI) was hindered by the high OM content. According to sequential extractions, Cr was mainly associated to the soil oxidisable fraction (74%) and to the residual fraction (25%). The amount of Cr potentially bioavailable for plant uptake (DTPA-extractable) was negligible. Characterization of soil thin sections by micro X-ray fluorescence (μXRF) and field emission scanning electron microscopy coupled with microanalysis (FEGSEM-EDX) showed that Cr was mainly distributed in aggregates ranging from tens micrometres to few millimetres in size. These aggregates were coated with an aluminosilicate layer and contained, in the inner part, Cr, Ca, Zn, P, S and Fe. Hyperspectral elaboration of μXRF data revealed that polluted soils were characterised by an exogenous organic-rich fraction containing Cr (not present in the control), and an endogenous aluminosilicate fraction (present also in the control), coating the Cr-containing aggregates. Analyses by high-resolution micro X-ray computed tomography (μCT) revealed a different morphology of the soil aggregates in polluted soils compared with the control. The finding of microscopic leather residues, combined with the results of bulk- and micro-characterizations, suggested that Cr pollution was likely ascribable to soil amendment with tannery waste-derived matrices. However, over the years, a natural process of Cr stabilization occurred in the soil thus reducing the environmental risks.