The effects of sulfur compounds on the migration of a semi-volatile heavy metal (cadmium) during sludge incineration were investigated with two methods, i.e., experiments in a tubular furnace reactor and thermodynamic equilibrium calculations. The representative typical sludge with and without the addition of sulfur compounds was incinerated at 850 °C. The partitioning of Cd among the solid phase (bottom ash) and gas phase (fly ash and flue gas) was quantified. The results indicate that sulfur compounds in the elemental form and a reduced state could stabilize Cd in the form of CdS, aluminosilicate minerals, and polymetallic sulfides, whereas sulfur in the oxidized forms slightly increases Cd volatilization during incineration. For Cd solidification points, the inhibition effect on the volatilization of Cd is as follows: S > Na₂SO₄> Na₂S. Chemical equilibrium calculations indicate that sulfur binds with Cd and alters Cd speciation at low temperatures (<950 K). Furthermore, SiO₂- and Al₂O₃-containing minerals can function as sorbents stabilizing Cd as condensed phase solids (CdSiO₄and CdAl₂O₄) according to the results of equilibrium calculations. These findings provide useful information for understanding the partitioning of Cd and thus facilitate the development of strategies to control Cd volatilization during sludge incineration.

Brominated flame retardants (BFRs, including polybrominated diphenyl ethers (PBDEs) and tetrabromobisphenol-A (TBBPA)) and metals (Cu, Zn, Pb, Cd, Ni, Hg and As) in sediments, soils and herb plants from unregulated e-waste disposal sites were examined. The metal concentrations, ∑PBDE and TBBPA concentrations in all samples from the examined e-waste dismantling sites were relatively high in comparison with those of rural and urban areas around the world. The PBDE and TBBPA levels in soils significantly decreased with increasing distance from the e-waste dismantling sites, indicating that PBDEs and TBBPA had similar transport potential from the e-waste dismantling process as a point source to the surrounding region. BDE-209 and TBBPA predominated in all samples, which is consistent with the evidence that the deca-BDE and TBBPA commercial mixtures were extensively used in electronic products. Metals, PBDEs and TBBPA displayed significant positive correlations with TOC, whereas the correlations with pH were insignificant, indicating that TOC was a major factor governing the spatial distribution, transportation and fate in sediments and soils. A significant relationship between log-transformed metals and BFR concentrations indicated common pollution sources. Moreover, cluster analysis and principal component analysis further confirmed that the metals and BFRs had a common source, and penta- and deca-BDE commercial products may be two sources of PBDEs in this region.

Concentrations of eight heavy metals (arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb), and zinc (Zn)) were measured in 92 topsoil samples collected from agricultural areas in Daye City to (1) assess the distribution of these heavy metals, (2) discriminate natural and anthropic contributions, and (3) identify possible sources of pollution. Mean concentrations of As, Cd, Cu, and Zn in the investigated soils were 23.8, 1.41, 105, and 159 mg kg⁻¹, respectively. These values were higher, in some cases by several orders of magnitude, than their corresponding background values. Estimated ecological risks, based on contamination factors and potential ecological risk indexes, were mostly low, but were considerable for As and Cd. A range of basic and multivariate statistical analyses (Pearson’s correlation analysis, hierarchical cluster analysis, and principal component analysis) clearly revealed two distinct metal groups, comprising As/Cd/Cu/Zn and Cr/Ni/Hg/Pb, whose concentrations were closely associated with the distribution and pollution characteristics of industries in and around the city. Results demonstrated that As/Cd/Cu/Zn were indicators of anthropic pollution, while Cr/Hg/Ni/Pb were from parent materials. Maps of pollutant distribution compiled for the entire arable area further indicated that non-ferrous metal smelting and mining is the main source of diffuse pollution, and also showed the contribution of point source pollution to metal concentrations in agricultural topsoil. Results of this study will be useful for planning, risk assessment, and decision making by environmental managers in this region.

Precipitation of salts—mainly hydrated Mg-Na sulfates—in building materials is rated as one of the most severe threats to the preservation of our architectural and cultural heritage. Nevertheless, the origin of this pathology is still unknown in many cases. Proper identification of the cause of damage is crucial for correct planning of future restoration actions. The goal of this study is to identify the source of the degradation compounds that are affecting the 15th-century limestone sculptures that decorate the retro-choir of Burgos Cathedral (northern Spain). To this end, detailed characterization of minerals by in situ (Raman spectroscopy) and laboratory techniques (XRD, Raman and FTIR) was followed by major elements (ICP and IC) and isotopic analysis (δ³⁴S and δ¹⁵N) of both the mineral phases precipitated on the retro-choir and the dissolved salts in groundwater in the vicinity of the cathedral. The results reveal unequivocal connection between the damage observed and capillary rise of salts-bearing water from the subsoil. The multianalytical methodology used is widely applicable to identify the origin of common affections suffered by historical buildings and masterpieces.

Volatile organic compounds (VOCs) may be emitted from surfaces indoors leading to compromised air quality. This study scrutinized the influence of relative humidity (RH) on VOC concentrations in a building that had been subjected to water damage. While air samplings in a damp room at low RH (21–22 %) only revealed minor amounts of 2-ethylhexanol (3 μg/m³) and 2,2,4-trimethyl-1,3-pentanediol diisobutyrate (TXIB, 8 μg/m³), measurements performed after a rapid increase of RH (to 58–75 %) revealed an increase in VOC concentrations which was 3-fold for 2-ethylhexanol and 2-fold for TXIB. Similar VOC emission patterns were found in laboratory analyses of moisture-affected and laboratory-contaminated building materials. This study demonstrates the importance of monitoring RH when sampling indoor air for VOCs in order to avoid misleading conclusions from the analytical results.

Natural estrogens are important endocrine disrupting compounds (EDCs), which may pose adverse effects on our environment. To avoid time-consuming sample preparation and chemical analysis, estimation of their concentrations in municipal wastewater based on their human urine/feces excretion rates has been generally adopted. However, the data of excretion rates available are very limited and show significant difference among countries. In the context of increasing reporting on the concentrations of natural estrogens in municipal wastewater around the world, this study presented a simple method to estimate their human excretion rates based on the concentrations of natural estrogens in raw sewage. The estimated human excretion rates of natural estrogens among ten countries were obtained, which totally covered over 33 million population. Among these, Brazilians had the largest excretion rates with estrone (E1) and 17β-estradiol (E2) as 236.9 and 60 μg/day/P, respectively, while Iran had the lowest value of 2 μg/day/P for E1 and 0.5 μg/day/P for E2. The average estimated human excretion rates of E1, E2, and estriol (E3) are 17.3, 6.4, and 39.7 μg/day/P, respectively. When the estimated human excretion rates obtained were applied for prediction, the predicted results showed better accuracies than those based on human urinary/feces excretion rates. The method in this study is simple, cost-effective and time-saving, which may be widely applied.

This study reports the chemical bioavailability of several potentially toxic elements (Zn, Pb, Cd, As, and Sb) in contaminated Technosols from two former smelting and mining areas. Though these elements have long been recognized as potentially harmful elements, understanding of their toxicity and environmental behavior in Technosols developed on former mining and smelting sites are more limited, particularly for As and Sb. Surface soils were sampled from metallophyte grassland contaminated with Zn, Pb, and Cd located at Mortagne-du-Nord (North France) and from a former mining settling basin contaminated with As, Pb, and Sb located at la Petite Faye (Limoges, France). Various selective single extraction procedures (CaCl₂, NaNO₃, NH₄NO₃, DTPA, and EDTA) were used together with germination tests with dwarf beans whose shoots were analyzed for their potentially toxic element concentrations after 21 days of growth. The extraction capacity of the potentially toxic elements followed the order EDTA > DTPA > NH₄NO₃ > CaCl₂ > NaNO₃for both studied areas. Pearson’s correlation coefficient analysis between the concentrations of potentially toxic elements accumulated in bean primary leaves or their mineral mass with their extractable concentrations showed a positive significant correlation with dilute CaCl₂and nitrate solutions extraction procedures. In contrast, for all studied elements, except Pb, the complexing and chelating extractants (EDTA and DTPA) exhibited poor correlation with the dwarf bean leaves concentrations. Moreover, results showed that the 0.01 M CaCl₂extraction procedure was the most suitable and provided the most useful indications of metal phytoavailability for studied elements.

Twenty-four surface sediment samples were collected from Liaohe River in June 2014 for the analysis of total concentrations of Cu, Pb, Zn, Cd, Ni, Fe, and Mn. The spatial distribution of heavy metals in Liaohe River was site specific, with Hun River as the most polluted river mainly affected by industrial and human activities. The contents of acid-volatile sulfide (AVS) and simultaneously extracted metals (SEMs) in Liaohe River varied significantly, ranging from 0.03 to 19.4 μmol/g and 0.14 to 10.8 μmol/g, respectively. Sulfate-reducing bacteria (SRB) community size, organic matter and sulfate availability, and sediment redox status may be the main factors affecting the AVS distribution. Among all the acid-extracted metals, Zn was dominant in all samples, whereas much more toxic Cd contributed less than 1.0 % to the total SEMs. Sediment quality guidelines (SQGs) and AVS-SEM models were used to predict the sediment toxicity. Results revealed that only a small portion of sites exhibited potential metal toxicity to aquatic biota, while adverse effects should rarely occur in majority of sites. Comparison of the two assessment methods showed inconsistent results, indicating that each method had its own limitations. The combination of different methods will be more convincing as to the sediment quality assessment.

A rarely used hydroponic plant root mat filter (PRMF, of 6 m²) and a horizontal subsurface flow constructed wetland (HSSF CW, of 6 m²), operating in continuous flow and discontinuous outflow flushing modes, were investigated for treating sulfate-rich and organic carbon-lean groundwater contaminated with monochlorobenzene (MCB); 1,2-dichlorobenzene (1,2-DCB); 1,4-dichlorobenzene (1,4-DCB); and 2-chlorotoluene. Whereas the mean inflow loads ranged from 1 to 247 mg m⁻²days⁻¹, the range of mean inflow concentrations of the chlorobenzenes recorded over a period of 7 months was within 0.04 and 8 mg L⁻¹. A hydraulic surface loading rate of 30 L m⁻²days⁻¹was obtained in both systems. The mean load removal efficiencies were found to vary between 87 and 93 % in the PRMF after a flow path of 4 m, while the removal efficiencies were found to range between 46 and 70 % and 71 to 73 % in the HSSF CW operating in a continuous flow mode and a discontinuous outflow flushing mode, respectively. Seasonal variations in the removal efficiencies were observed for all low-chlorinated hydrocarbons both in the PRMF and the HSSF CW, whereby the highest removal efficiencies were reached during the summer months. Sulfide formation occurred in the organic carbon-lean groundwater particularly in summer, which is probably due to the plant-derived organic carbon that fostered the microbial dissimilatory sulfate reduction. Higher redox potential in water was observed in the PRMF. In conclusion, the PRMF could be an option for the treatment of water contaminated with compounds which in particular need oxic conditions for their microbial degradation, such as in the case of low-chlorinated benzenes.

Phytoextraction of mercury-contaminated soils is a new strategy that consists of using the higher plants to make the soil contaminant nontoxic. The main problem that occurs during the process is the low solubility and bioavailability of mercury in soil. Therefore, some soil amendments can be used to increase the efficiency of the Hg phytoextraction process. The aim of the investigation was to use the commercial compost from municipal green wastes to increase the efficiency of phytoextraction of mercury-contaminated soil by Lepidium sativum L. plants and determine the leaching of Hg after compost amendment. The result of the study showed that Hg can be accumulated by L. sativum L. The application of compost increased both the accumulation by whole plant and translocation of Hg to shoots. Compost did not affect the plant biomass and its biometric parameters. Application of compost to the soil decreased the leaching of mercury in both acidic and neutral solutions regardless of growing medium composition and time of analysis. Due to Hg accumulation and translocation as well as its potential leaching in acidic and neutral solution, compost can be recommended as a soil amendment during the phytoextraction of mercury-contaminated soil.