Development and Application of Methods for the Assay of Neptunium in Environmental Matrices

Inductively coupled plasma mass-spectrometry (ICP-MS) and neutron activation analysis (NAA) techniques have been investigated as rapid, alternative methods for the analysis of 237 Np and other long-lived actinides in environmental matrices. By comparison to the more routine a-spectrometric method, equivalent, if not improved, detection limits for ICP-MS and NAA have been found. Radiochemical separation and pre-concentration are required for all the methods studied. In this work, anion exchange and TTA solvent extraction of Np IV from hydrochloric acid media were used to separate Np from potential interferences from the naturally occurring nuclides of uranium. The degree of interference was found to vary for each approach and was quite severe in the case of NAA. Analysis by ICP-MS tolerates a lower degree of chemical purification and results in a significant increase in sample throughput. The rapid, mass-scanning facilities of the instrument have allowed multiactinide determination on single samples and have provided important additional information concerning plutonium nuclides in environmental samples. In the absence of suitable certified reference materials, the accuracy and precision of the ICP-MS technique were determined by a series of laboratory intercomparison and replicate analyses. On this basis, the reported measurements of 237Np and plutonium nuclides were considered valid. The ICP-MS method developed here has been applied to the routine analysis of 237Np and plutonium nuclides in samples of soils and sediments from W. Cumbria, known to be contaminated by discharges from the BNFL fuel re-processing plant at Sellafield. Concentrations ranging from 3.16 to 0.004 Bq kg-1 237Np have been measured with excellent precision. Typically, an exponential decrease of 237Np activity with depth has been found in a number of soil profiles. The pattern is the same as that found for other anthropogenic nuclides in the profiles but, when the effect of profile density variation is considered, it appears that a component of the neptunium is present in a more mobile form and is responsible for a degree of smearing of its distribution down the soil profile. During the transfer of Sellafield-derived 237Np from the BNFL, through the marine environment to a number of terrestrial sampling locations in W. Cumbria, the activity ratios of 237Np to 239,240Pu, 241Am and 137Cs change in a manner which implies that there is a loss of neptunium from the solid phase. Detailed studies of the chemical association of neptunium in samples of silt and surface soil show that, compared to the other transuranic nuclides studied, a significant proportion of the element is associated with the more sensitive phases the exchangeable and adsorbed components, including carbonate. The organic matter and residual phases are nevertheless found to be significant and merit further study

It’s time to replace the term “heavy metals” with “potentially toxic elements” when reporting environmental research

International audienceEven if the Periodic Table of Chemical Elements is relatively well defined, some controversial terms are still in use. Indeed, the term "heavy metal" is a common term used for decades in the natural sciences, and even more in environmental sciences, particularly in studies of pollution impacts. As the use of the term appears to have increased, we highlight the relevance of the use of the term "Potentially Toxic Element(s)", which needs more explicit endorsement, and we illustrate the chemical elements that need to be considered

Development and Validation of a Box and Flux Model to Describe Major, Trace and Potentially Toxic Elements ({PTEs}) in Scottish Soils

The box and flux model is a mathematical tool used to describe and forecast the major and trace elements perturbations of the Earth biogeochemical cycles. This mathematical tool describes the biogeochemical cycles, using kinetics of first, second and even third order. The theory and history of the box and flux modeling are shortly revised and discussed within the framework of Jim Lovelok’s Gaia theory. The objectives of the investigation were to evaluate the natural versus anthropic load of Potentially Toxic Elements (PTEs) of the Scottish soils, investigate the soil components adsorbing and retaining the PTEs in non-mobile species, evaluate the aging factor of the anthropic PTEs and develop a model which describes the leaching of PTEs in layered soils. In the Scottish land, the soil-to-rock enrichment factorinversely correlates with the boiling point of the PTEs. The same is observed in NW Italy and USA soils, suggesting the common source of the PTEs. The residence time in soils of the measured PTEs linearly correlates with the Soil Organic Matter (SOM). The element property which mostly explains the adsorption capacity for PTEs’ is the ionic potential (IP). The downward migration rates of the PTEs inversely correlate with SOM, and in Scottish soil, they range from 0.5 to 2.0 cm·year−1. Organic Bentoniteis the most important soil phase adsorbing cation bivalent PTEs. The self-remediation time of the polluted soil examined ranged from 50 to 100 years. The aging factor, the adsorption of PTEs’ into non-mobile species, and occlusion into the soil mineral lattice was not effective. The box and flux model developed, tested and validatedhere does not describe the leaching of PTEs following the typical Gaussian shape distribution of the physical diffusion models. Indeed, the mathematical model proposed is sensitive to the inhomogeneity of the layered soils

A critical review of resistance and oxidation mechanisms of Sb-oxidizing bacteria for the bioremediation of Sb(Ⅲ) pollution

Antimony (Sb) is a priority pollutant in many countries and regions due to its chronic toxicity and potential carcinogenicity. Elevated concentrations of Sb in the environmental originating from mining and other anthropogenic sources are of particular global concern, so the prevention and control of the source of pollution and environment remediation are urgent. It is widely accepted that indigenous microbes play an important role in Sb speciation, mobility, bioavailability, and fate in the natural environment. Especially, antimony-oxidizing bacteria can promote the release of antimony from ore deposits to the wider environment. However, it can also oxidize the more toxic antimonite [Sb(III)] to the less-toxic antimonate [Sb(V)], which is considered as a potentially environmentally friendly and efficient remediation technology for Sb pollution. Therefore, understanding its biological oxidation mechanism has great practical significance to protect environment and human health. This paper reviews studies of the isolation, identification, diversity, Sb(III) resistance mechanisms, Sb(III) oxidation characteristics and mechanism and potential application of Sb-oxidizing bacteria. The aim is to provide a theoretical basis and reference for the diversity and metabolic mechanism of Sb-oxidizing bacteria, the prevention and control of Sb pollution sources, and the application of environment treatment for Sb pollution

Treatment of environmental contamination using sepiolite:current approaches and future potential

To evaluate the potential of sepiolite-based materials to resolve environmental pollution problems, a study is needed which looks at the whole life cycle of material application, including the residual value of material classified as waste from the exploitation of sepiolite deposits in the region or from its processing and purification. This would also maximize value from the exploitation process and provide new potential for local waste management. We review the geographical distribution of sepiolite, its application in the treatment of potentially toxic elements in soil and across the wider landscape, an assessment of modification and compositional variation of sepiolite-based applications within site remediation and wastewater treatment. The potential of sepiolite-based technologies is widespread and a number of processes utilize sepiolite-derived materials. Along with its intrinsic characteristics, both the long-term durability and the cost-effectiveness of the application need to be considered, making it possible to design ready-to-use products with good market acceptance. From a critical analysis of the literature, the most frequently associated terms associated with sepiolite powder are the use of lime and bentonite, while fly ash ranked in the top ten of the most frequently used material with sepiolite. These add improved performance for the inclusion as a soil or wastewater treatment options, alone or applied in combination with other treatment methods. This approach needs an integrated assessment to establish economic viability and environmental performance. Applications are not commonly evaluated from a cost–benefit perspective, in particular in relation to case studies within geographical regions hosting primary sepiolite deposits and wastes that have the potential for beneficial reuse

Removal of manganese(II) from acid mine wastewater:a review of challenges and opportunities with special emphasis on Mn-oxidizing bacteria and microalgae

Many global mining activities release large amounts of acidic mine drainage with high levels of manganese (Mn) having potentially detrimental effects on the environment. This review provides a comprehensive assessment of the main implications and challenges of Mn(II) removal from mine drainage. We first present the sources of contamination from mineral processing, as well as the adverse effects of Mn on mining ecosystems. Then the comparison of several techniques to remove Mn(II) from wastewater, as well as an assessment of the challenges associated with precipitation, adsorption, and oxidation/filtration are provided. We also critically analyze remediation options with special emphasis on Mn-oxidizing bacteria (MnOB) and microalgae. Recent literature demonstrates that MnOB can efficiently oxidize dissolved Mn(II) to Mn(III, IV) through enzymatic catalysis. Microalgae can also accelerate Mn(II) oxidation through indirect oxidation by increasing solution pH and dissolved oxygen production during its growth. Microbial oxidation and the removal of Mn(II) have been effective in treating artificial wastewater and groundwater under neutral conditions with adequate oxygen. Compared to physicochemical techniques, the bioremediation of manganese mine drainage without the addition of chemical reagents is relatively inexpensive. However, wastewater from manganese mines is acidic and has low-levels of dissolved oxygen, which inhibit the oxidizing ability of MnOB. We propose an alternative treatment for manganese mine drainage that focuses on the synergistic interactions of Mn in wastewater with co-immobilized MnOB/microalgae

New models to reduce the health risks of informal WEEE recyclers in MTN phone village, Rumukurushi, Port Harcourt, Nigeria

Waste electrical and electronic equipment (WEEE) management in Port Harcourt, an oil-producing city in Nigeria, has become an environmental challenge for the location. WEEE recycling is predominantly managed by informal recyclers, who lack the skills to perform risk-free recycling, hence raising health risks to individuals in associated communities and degrading the environment. Formal recycling, which embraces the best practices for effective WEEE management, is faced with several limitations, such as a lack of detailed guidelines on waste recycling, reuse, and final disposal techniques, with no opportunities for landfilling. A qualitative approach was adopted for this study. Data were gathered via questionnaires and analysed graphically. A background literature review of the assessment of informal recycling methods and associated challenges was performed. Hence, a new concept for the local management of WEEE processing was introduced. This concept limits the role of informal recyclers to WEEE collection. In this case, informal recyclers are paid for WEEE collection; they no longer engage in further WEEE processing. The results show that 48% and 40% agree to partner and collaborate with government agencies, respectively. Conversely, 52% and 40% agree and strongly agree, respectively, to limit their activities to WEEE collection only if the government is willing to pay for the services