Heavy metal distribution in some French forest soils: evidence for atmospheric contamination

This study is one of very few dealing with the distribution and the origin of heavy metals in French soils from a priori non-polluted forest areas. The abundance of heavy metals measured in these soils decreases as follows: Cr) Zn)Pb)Ni)Cu)Co4Cd. Total concentrations of Pb, Cr and Ni in some soils exceed the European thresholds for non-polluted soils and even the French association of normalization critical values for sludge spreading. The lowest heavy metal contents are observed in acid soils while the highest concentrations are in the calcaric cambisol and in the mollic andosol, which is rather scarce as compared with the other French forest soils. With the exception of the podzol, Cr and Ni concentrations increase with depth in all soil profiles. The distribution pattern of Co, Cu, Zn depends on the soil characteristics. In some acid soils, however, Cu and Zn decrease with depth. Pb and Cd are accumulated in the upper soil horizons. Heavy metals accumulate in deep soil horizons in relation to important clay content in the dystric planosol and stagnic luvisol. The concentration of each heavy metal is always controlled by different parameters (soil pH, iron and aluminum oxide content, clay content, organic matter and cation exchange capacity), which are heavy metal specific. This study highlights the metal-trapping character of andosol and calcaric soil, the weak heavy metal retention in acid soils, the leaching and trapping character in leached clayed soils, and the migration of heavy metals in the podzol. Pb and Cr concentrations indicate a significant enrichment in surface horizons from various soils in areas which receive significant acid atmospheric pollution. Particularly, the highest Pb content is observed in a soil located in the N-NE part of France. Lead isotope ratios measured in the cambic podzol and the calcaric cambisol, exhibit the importance of the anthropogenic sources and particularly the influence of global atmospheric inputs from leaded gasoline compared to regional and local industrial emissions. The anthropogenic Pb contribution is estimated to 83, 30 and 11%, respectively, for surface, intermediate and deep horizons of the cambic podzol located in the northern part of France, and to 68% in surface horizon of the calcaric cambisol located in the Alps

Photoactive Materials for the Catalytic Decomposition of Water Pollutants

The use of UV and Vis light (in the form of solar energy) in the presence of semiconductor nanostructured materials as photocatalysts is effective for the adequate removal of a wide spectrum of pollutants (resistant to other degradation techniques) in various types of wastewater, which are important elements of the development of science related to photocatalysis [...

Limitation of environmental impact of metallurgical waste by bioleaching

Various bioleaching processes are applied to recover valuable elements from low-grade ores and metallurgical waste. The activity of microorganisms leads to solubilization of metals from solid substrates and, in this way, makes possible recovery of elements from solutions. The study of wastes from the nickel-chromium steelworks in Szklary showed that a mobile fraction of elements remaining in residues from bioleaching process was substantially larger than in raw waste material. The highest mobility was displayed by metals in wastes leached by heterotrophic bacteria prior to autotrophic ones. In that case the mobile fraction makes up 60–80% of the total concentration of Ni, Cr, Cu and Zn. Storage of bioleached mine tailings increases risk of permeation of hazardous matter to aquifers. When this is the case, a careful flushing and use of metal-binding materials such as bentonite, zeolites, cement, and commercial preparations containing these ingredients are recommended. The obtained results showed that concrete, which is the cheapest of the applied materials, bound almost entirely the mobile fractions of Ni, Cr, Co, Pb, Cu and Zn

Photoactive Materials for Decomposition of Organic Matter Prior to Water Analysis—A Review Containing Original Research

Water plays a fundamental role in meeting the basic needs of society. Surface waters contain numerous organic pollutants, such as pesticides, drugs, and surfactants. The use of photolysis processes in organic matter degradation not only has practical applications in wastewater treatment but is also of major importance in the pretreatment of samples prior to the trace analysis of numerous analytes. The heterogeneous degradation is simple to implement prior to ultra-traces determination and is the only one allowed before the speciation analysis. Speciation analysis is currently the most important environmental challenge. The analysis of water, including tests associated with wastewater pretreatment and the monitoring of aqueous ecosystems, is the largest segment of environmental analysis. In the trace analysis of water, organic compounds are the principal interfering compounds reducing the quality of the obtained results or even preventing the determination of the examined analytes altogether. Some analytical techniques do not perform well in the presence, for example, of surfactants, so mineralization is sometimes required. Advanced oxidation processes are used to remove interfering organic compounds. The oxidation can be performed using homogenous photolysis (UV mineralization with hydrogen peroxide addition), while heterogenous photolysis using semiconductors helps to increase the removal efficiency of interferents dissolved in water. Utilizing semiconductor nanostructured materials as photocatalysts has been shown to be effective for the adequate removal of a wide spectrum of pollutants in water. Several semiconductor systems are used in the degradation of organic compounds, e.g., TiO2, Fe3O4, WO3, Fe2O3, ZnO, and mixtures of these oxides enriched with various precious metals, such as silver or gold. It is very challenging to manage the selectivity and reduction power so that organic compounds can be degraded but without disturbing the speciation of As, Cr, or Tl. Chemical modification of samples and the selection of semiconductor layers, light wavelength, and pH allow for the targeted degradation of specific compounds but may also indirectly affect the analysis of water samples. This review is a presentation of the state of the art of photocatalysis as a simple and effective technique for sample pretreatment in ultra-trace and speciation analysis and its critical as well as unpublished data related to this topic

Application of Hierarchical Nanostructured WO3 and Fe2O3 Composites for Photodegradation of Surfactants in Water Samples

This study describes the utilization of hierarchical photoactive surface films for the decomposition of surfactants in water samples (with different pH). Photoactive films, containing tungsten (VI) oxide and iron (III) oxide (hematite), were deposited in a systematic and controlled manner using a layer-by-layer method. Physicochemical properties of the photoactive materials were developed and characterized using XRD analysis, Raman spectroscopy, water contact angle, voltammetry, and microscopic (SEM) techniques. The resulting multilayer films showed attractive performances in the photodegradation of the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant (1,1,3,3-tetramethylbutyl)phenyl-polyethylene glycol (Triton™ X-144) under solar light irradiation. The efficiency of the surfactants’ photodegradation was evaluated with a “test” based on a method, which is extremely sensitive to surfactants’ interference, with trace analysis of Pb using anodic stripping voltammetry on mercury electrodes (recovery study). The usefulness of hierarchical photoactive systems in the photodegradation of both surfactants is demonstrated in the presence and absence of the applied bias voltage. The maximum decomposition times were 2–3 h and 30 min, respectively. Furthermore, a properly designed layer system may be proposed, matching the pH of the water sample (depending on the treatment on the sampling side)