Relation between solid phase speciation and oral/lung bioaccessibility of metal(loid)s polluted soils in inhabited area: Contribution of synchrotron-based experiment.

The presence of contaminated sites/soils in or near cities can pose significant risks to public health. The city of Viviez (France) was taken in reference site bears significant industrial responsibility, particularly in zinc metallurgy, with the presence of a now rehabilitated smelter. This has led to soil contamination by zinc (Zn), lead (Pb), arsenic (As), and cadmium (Cd), with concentrations reaching up to 4856 mg kg-1, 1739 mg kg-1, 195 mg kg-1, and 110 mg kg-1, respectively. The aim of this study is to comprehend the contamination patterns of the site post-rehabilitation, the geochemical behavior of each element, and their speciation (analyzed through BCR, XRD, and XANES) in relation to associated health risks due to metals accessibility for oral ingestion and inhalation by the local population. The findings revealed that elements inducing health risks were not necessarily those with the highest metal contents. All results are discussed in terms of the relationship between element speciation, stability of bearing phases, and their behavior in different media. XANES is an important tool to determine and estimate the Pb-bearing phases in garden soils, as well as the As speciation, which consist of Pb-goethite, anglesite, and Pb-humate, with variations in proportions (the main phases being 66 %, 12 % and 22 % for Pb-goethite, anglesite, and Pb-humate, respectively) whereas As-bearing phase are As(V)-rich ferrihydrite-like. A new aspect lies in the detailed characterization of solid phases before and after bioaccessibility tests, to qualify and quantify the bearing phases involved in the mobility of metallic elements to understand the bioaccessibility behavior. Ultimately, the health risk associated with exposure to inhabitants, in terms of particle ingestion and inhalation, was assessed. Only ingestion-related risk was deemed unacceptable due to the levels of As and Pb.

A fast one-pot synthesize of crystalline anglesite by hydrothermal synthesis for environmental assessment on pure phase.

Anglesite (PbSO4) is a lead sulfate that belongs to the barite group and is naturally ubiquitous in the environment. This work describes a simple way to synthesize crystalline lead sulfate by using a straightforward hydrothermal procedure. Typically, Pb(NO3)2 and Fe2(SO4)3 precursors were mixed and heated at 94 °C for 24 h. The synthesized samples have been characterized by coupling X-Ray diffraction (XRD) to spectroscopic methods (FTIR and micro-Raman), X-ray absorption spectroscopy (XAS), and electronic microscopy (SEM and TEM). In fine, the results about this new well crystalline synthetic anglesite confirm the efficiency and the importance of this cheap protocol and the synthesized phases obtained. Moreover, the environmental stability and bioaccessibility of anglesite have been done to evaluate environmental stability of anglesite under various physico-chemical conditions and sanitary risks. Finally, the paper allows to obtain precise data on a pure phase in order to be able to more easily evaluate and understand the role of anglesite in as-polluted sites and soils.

Investigating the relationship between speciation and oral/lung bioaccessibility of a highly contaminated tailing: contribution in health risk assessment.

Anthropogenic activities such as industrial, mining, or agricultural are the main sources of environmental contamination. One of the most problematic contaminations concerns metals and metalloids from mining activities. This contamination raises the question of the environmental risk induced and the spread of this pollution (geographical and trophic) and the associated health risk. The integrated, multi-analytical approach of this study conducted on the mining district of Cartagena-La Union (Murcia, Spain) as part of the Interreg SUDOE European project "Soil Take Care" aims to (i) precisely define the speciation of contaminants of interest (Zn, Pb, Cd, As), (ii) predict the environmental risk related to storage stability, and (iii) establish the link between the speciation of the bearing phases and the associated health risk. To do this, a representative zone in the Cartagena-La Union mining district close to the populations was chosen. A physic-chemical characterization of the samples was performed (pH, electrical conductivity, CEC, and total metal(loid) concentrations), and the mineralogy was determined using XRD and SEM-EDS. The environmental risk was highlighted from sequential BCR-type extractions and EN-12457 leaching tests. Finally, the health risk was defined using the PSF inhalation bioaccessibility test and UBM bioaccessibility protocol (based on an operational chemical methodology mimicking soil ingestion and its residence in the gastrointestinal tract of the human body). These analyses revealed 2 groups of samples with distinct behavior. The first group of samples presents relatively stable bearing phases, mainly found in the residual fraction (As and Pb), presenting only a low health risk (very low bioaccessible). The second group consists of Cd and/or Zn-bearing phases, mainly labile (resulting from dissolution/precipitation phenomena), while gastric bioaccessibility reaches more than 85%. Note that Pb, Cd, and Zn have the potential to cause non-carcinogenic risks to children and As and Pb present a carcinogenic risk for children and adults even if only the bioaccessible fraction is considered. It has therefore been shown that the meteoric alteration of the tailing induces a change in speciation leads to an increase in environmental and health risks. These results are essential because they highlight the need for an integrated approach in order to clearly highlight the presence of risks but also that this approach will allow a better understanding of the potential rehabilitation path of this site.

Environmental stability and oral bioaccessibility of synthetic Pb-bearing phases to better evaluate soil health risks.

A large amount of contaminated sites is shown around the world which may induce a health risk due to the presence of contaminants such as metal (loïd)s bearing phases. Health risk assessment is based on contaminant bioaccessibility. However, it is needed to understand every contaminant behavior in physiological matrix to be a realistic way to assess and interpret these sanitary risks. Due to the complexity of contaminated soil matrix, the use of synthetic minerals seems to be the better tool to understand their behavior in physiological matrix. Then, this study aims to highlight the environmental stability and the behavior during bioaccessibility ingestion (UBM) of selected synthetic lead-bearing phases. For this purpose, three Pb phases (galena, beudantite, and anglesite) commonly found in contaminated environments (particularly mining sites) were synthesized and characterized (structurally and morphologically). The sequential BCR extractions have shown that most of the lead is in a stable and non-mobilizable form (up to 93%). The lead present in these phases represents very few risks of migrating into the environment during physicochemical condition changes. The results of the bioaccessibility revealed a relatively high stability of the pure bearing phases in the physiological matrix. Lead is stable for 97.0% to 99.2% during the gastric phase and 97.0% to 99.9% during the gastro-intestinal phase. Moreover, the synthetic mixtures of galena/beudantite and anglesite/beudantite have been realized considering the proportions commonly found in the mining contexts. This has shown a similar behavior compared to pure phases except in the case of the anglesite mixture inducing a clear cocktail effect (drastic increase of Pb amount from gastro-intestinal phases). At last, this study is a first and interesting step to assess the behavior of these bearing phases in heterogeneous and complex medium such as soil.