Determinations of the mobility of metals from tailings is a critical part of any assessment of the environmental impacts of mining activities. The leaching of thorium and uranium from the tailings of different processing stages of a niobium mine was investigated for several pH, ionic strengths and concentrations of natural organic matter (NOM). The pH of the leaching solution did not have a noticeable impact on the extraction of Th, however, for pH values below 4, increased U mobilization was observed. Similarly, only a small fraction of Th (0.05%, ≤15 μg kg⁻¹) and U (1.22%, ≤6 μg kg⁻¹) were mobilized from the tailings in the presence of environmentally relevant concentrations of Ca, Mg or Na. However, in the presence of 10 mg L⁻¹ of fulvic acid, much higher concentrations of ca. 700 μg kg⁻¹ of Th and 35 μg kg⁻¹ of U could be extracted from the tailings. Generally, colloidal forms of Th and dissolved forms of U were mobilized from the tailings, however, in the presence of the fulvic acid, both dissolved and colloidal forms of the two actinides were observed. Single Particle ICP-MS was used to confirm the presence of Th (and U) containing colloids where significant numbers (up to 10⁷ mL⁻¹) of Th and U containing colloids were found, even in 0.2 μm filtered extracts. Although mass equivalent diameters in the range of 6–13 nm Th and 6–9 nm for U could be estimated (based upon the presence of an oxyhydroxide), most of the colloidal mass was attributed to larger (>200 nm) heterocomposite particles.

Nitrate (NO₃⁻) is a key component of secondary inorganic aerosols and PM₂.₅. However, the contributions of nitrogen oxides (NOₓ) emission sources to NO₃⁻ in PM₂.₅ remain poorly constrained. This study measured nitrogen (N) isotopes of NO₃⁻ (hereafter as δ¹⁵N-NO₃⁻) in PM₂.₅ collected at Beijing in 2014. We observed that δ¹⁵N-NO₃⁻ values in PM₂.₅ (−2.3‰ − 19.7‰; 7.3 ± 5.4‰ annually) were significantly higher in winter (11.9 ± 4.4‰) than in summer (2.2 ± 2.5‰). The δ¹⁵N differences between source NOₓ and NO₃⁻ in PM₂.₅ (hereafter as Δ values) were estimated by a computation module as 7.8 ± 2.2‰ − 10.4 ± 1.6‰ (8.8 ± 2.4‰). Using the Δ values and δ¹⁵N values of NOₓ from major fossil (coal combustion, vehicle exhausts) and non-fossil sources (biomass burning, microbial N cycle), contributions of major NOₓ sources to NO₃⁻ in PM₂.₅ were further estimated by the SIAR model. We found that seasonal variations of δ¹⁵N-NO₃⁻ values in PM₂.₅ of Beijing were mainly caused by those of NOₓ contributions from coal combustion (38 ± 10% in winter, 20 ± 9% in summer). Annually, NOₓ from coal combustion, vehicle exhausts, biomass burning, and microbial N cycle contributed 28 ± 12%, 29 ± 17%, 27 ± 15%, and 16 ± 7% to NO₃⁻ in PM₂.₅, respectively, showing actually comparable contributions between non-fossil NOₓ (43 ± 16%) and fossil NOₓ (57 ± 21%). These results are useful for planning the reduction of NOₓ emissions in city environments and for elucidating relationships between regional NOₓ emissions and atmospheric NO₃⁻ pollution or deposition.

Excess ammonia (NH₃) emissions and deposition can have negative effects on air quality and terrestrial ecosystems. Identifying NH₃ sources is a critical step for effectively reducing NH₃ emissions, which are generally unregulated around the world. Stable nitrogen isotopes (δ¹⁵N) of ammonium (NH₄⁺) in precipitation have been directly used to partition NH₃ sources. However, nitrogen isotope fractionation during atmospheric processes from NH₃ sources to sinks has been previously overlooked. Here we measured δ¹⁵NNH₄⁺ in precipitation on a daily basis at a rural forested site in Northeast China over three years to examine its seasonal pattern and attempt to constrain the NH₃ sources. We found that the NH₄⁺ concentrations in precipitation ranged from 5 to 1265 μM, and NH₄⁺ accounted for 65% of the inorganic nitrogen deposition (20.0 kg N ha⁻¹ yr⁻¹) over the study period. The δ¹⁵N values of NH₄⁺ fluctuated from −24.6 to +16.2‰ (average −6.5‰) and showed a repeatable seasonal pattern with higher values in summer (average −2.3‰) than in winter (average −16.4‰), which could not be explained by only the seasonal changes in the NH₃ sources. Our results suggest that in addition to the NH₃ sources, isotope equilibrium fractionation contributed to the seasonal pattern of δ¹⁵NNH₄⁺ in precipitation, and thus, nitrogen isotope fractionation should be considered when partitioning NH₃ sources based on δ¹⁵NNH₄⁺ in precipitation.

Stable isotopes ratios (‰) of Hydrogen (δ2H) and Oxygen (δ1⁸O) were used to trace the groundwater recharge mechanism and geochemistry of arsenic (As) contamination in groundwater from four selected sites (Larkana, Naudero, Ghari Khuda Buksh and Dokri) of Larkana district. The stable isotope values of δ2H and δ1⁸O range from 70.78‰ to −56.01‰ and from −10.92‰ to −7.35‰, relative to Vienna Standard for Mean Ocean Water (VSMOW) respectively, in all groundwater samples, thus indicating the recharge source of groundwater from high-salinity older water. The concentrations of As in all groundwater samples were ranged from 2 μg/L to 318 μg/L, with 67% of samples exhibited As levels exceeding than that of World Health Organization (WHO) permissible limit 10 μg/L and 42% of samples expressed the As level exceeding than that of the National Environmental Quality Standard (NEQS) 50 μg/L. The leaching and vertical mixing with return irrigation water are probably the main processes controlling the enrichment of As in groundwater of Larkana, Naudero, Ghari Khuda Buksh and Dokri. The weathering of minerals mostly controlled the overall groundwater chemistry; rock-water interactions and silicate weathering generated yielded solutions that were saturated in calcite and dolomite in two areas while halite dissolution is prominent with high As area.

A Fenton like advanced oxidation process (AOP) employing scrap zerovalent iron (SZVI) and hydrogen peroxide (H2O2) was studied for industrial textile wastewater treatment from a textile manufacturing plant located at Medellín, Colombia (South America). The wastewater effluent studied contains a mixture of organic compounds resistant to conventional treatments. The effect of initial pH and SZVI concentration and H2O2 concentration were studied by a response surface methodology (RSM) Box-Behnken design of experiment (BBD). The combined SZVI/H2O2 process led to reductions of 95% color, 76% of chemical oxygen demand (COD) and 71% of total organic carbon (TOC) at optimal operating conditions of pH = 3, SZVI = 2000 mg/L and [H2O2] = 24.5 mM. Molecular weight distribution measurement (MWD), ultraviolet–visible (UV–Vis) spectroscopy, HPLC, biodegradability and toxicity were used to characterize the pollutants after the treatment process finding that the resulting effluent was polluted mostly by low molecular weight carboxylic acids. A remarkable biodegradability enhancement of the effluent was evidenced by a BOD5/COD ratio increase from 0.22 to 0.4; also, the SZVI/H2O2 process successfully reduced the toxicity from 60% to 20% of dead A. Salina crustaceans.

There is a growing conservation concern about the possible consequences of environmental contamination in the health of bat communities. Most studies on the effects of contaminants in bats have been focused on organic contaminants, and the consequences of bat exposure to metals and metalloids remain largely unknown. The aim of this study was to evaluate the suitability of external biological matrices (fur and wing membrane) for the assessment of exposure and bioaccumulation of metals in bats. The concentration of arsenic, cadmium, cobalt, chromium, copper, manganese, nickel, lead, selenium and zinc was measured in internal organs (liver, heart, brain), internal (bone) and external tissues (wing membrane, fur) collected from bat carcasses of four species (Hypsugo savii, Nyctalus leisleri, Pipistrellus pipistrellus, Pipistrellus pygmaeus) obtained in windfarm mortality searches. With the exception of zinc (P = 0.223), the results showed significant differences between the concentrations of metals in the analyzed tissues for all metals (P < 0.05). Significant differences were also found between organs/tissues (P < 0.001), metals (P < 0.001) and a significant interaction between organs/tissues and metals was found (P < 0.001). Despite these results, the patterns in terms of metal accumulation were similar for all samples. Depending on the metal, the organ/tissue that showed the highest concentrations varied, but fur and wing had the highest concentrations for most metals. The variability obtained in terms of metal concentrations in different tissues highlights the need to define standardized methods capable of being applied in monitoring bat populations worldwide. The results indicate that wing membrane and fur, biological matrices that may be collected from living bats, yield reliable results and may be useful for studies on bats ecotoxicology, coupled to a standardized protocol for large-scale investigation of metal accumulation.

Bed sediments and a dated sediment core were collected upstream and downstream from the city of Lyon (France) to assess the spatial and temporal trends of contamination by per- and polyfluoroalkyl substances (PFASs) in this section of the Rhône River. Upstream from Lyon, concentrations of total PFASs (ΣPFASs) in sediments are low (between 0.19 and 2.6 ng g⁻¹ dry weight - dw), being characterized by a high proportion of perfluorooctane sulfonate (PFOS). Downstream from Lyon, and also from a fluoropolymer manufacturing plant, ΣPFASs concentrations reach 48.7 ng g⁻¹ dw. A gradual decrease of concentrations is reported at the coring site further downstream (38 km). Based on a dated sediment core, the temporal evolution of PFASs is reconstructed from 1984 to 2013. Prior to 1987, ΣPFASs concentrations were low (≤2 ng g⁻¹ dw), increasing to a maximum of 51 ng g⁻¹ dw in the 1990s and then decreasing from 2002 to the present day (∼10 ng g⁻¹ dw). In terms of the PFAS pattern, the proportion of perfluoroalkyl sulfonic acids (PFSAs) has remained stable since the 1980s (∼10%), whereas large variations are reported for carboxylic acids (PFCAs). Long chain- (C > 8) PFCAs characterized by an even number of perfluorinated carbons represent about 74% of the total PFAS load until 2005. However, from 2005 to 2013, the relative contribution of long chain- (C > 8) PFCAs with an odd number of perfluorinated carbons reaches 80%. Such changes in the PFAS pattern likely highlight a major shift in the industrial production process. This spatial and retrospective study provides valuable insights into the long-term contamination patterns of PFAS chemicals in river basins impacted by both urban and industrial activities.

Many cities fail to meet air quality standards, which results in increased risk for pulmonary disorders, including asthma. Human and experimental studies have shown that diesel exhaust (DE) particles are associated with worsening of allergic asthma. Biodiesel (BD), a cleaner fuel from renewable sources, was introduced in the eighties. Because of the reduction in particulate matter (PM) emissions, BD was expected to cause fewer adverse pulmonary effects. However, only limited data on the effect of BD emissions in asthma are available.Determine whether BD exhaust exposure in allergic sensitized mice leads to different effects on inflammatory and functional responses compared to DE exposure.Balb/C mice were orotracheally sensitized with House Dust Mite (HDM) or a saline solution with 3 weekly instillations. From day 9 until day 17 after sensitization, they were exposed daily to filtered air (FA), DE and BD exhaust (concentration: 600 μg/m³ PM₂.₅). Lung function, bronchoalveolar lavage fluid (BALF) cell counts, cytokine levels (IL-2, IL-4, IL-5, IL-17, TNF-α, TSLP) in the BALF, peribronchiolar eosinophils and parenchymal macrophages were measured.HDM-sensitized animals presented increased lung elastance (p = 0.046), IgG1 serum levels (p = 0.029), peribronchiolar eosinophils (p = 0.028), BALF levels of total cells (p = 0.020), eosinophils (p = 0.028), IL-5 levels (p = 0.002) and TSLP levels (p = 0.046) in BALF. DE exposure alone increased lung elastance (p = 0.000) and BALF IL-4 levels (p = 0.045), whereas BD exposure alone increased BALF TSLP levels (p = 0.004). BD exposure did not influence any parameters after HDM challenge, while DE exposed animals presented increased BALF levels of total cells (p = 0.019), lymphocytes (p = 0.000), neutrophils (p = 0.040), macrophages (p = 0.034), BALF IL-4 levels (p = 0.028), and macrophagic inflammation in the lung tissue (p = 0.037), as well as decreased IgG1 (p = 0.046) and IgG2 (p = 0.043) levels when compared to the HDM group.The results indicate more adverse pulmonary effects of DE compared to BD exposure in allergic sensitized animals.

Urban trees have been assumed to effectively clean air particulate matter (PM), while the inter-species differences are not yet well defined, especially the PM chemical composition. In this study, PM from leaf surface and wax layer of 3 evergreen tree species (Juniper: Juniperus rigida; Black pine: Pinus tabuliformis var. mukdeais; Spruce: Picea koraiensis) were used for finding differences in PM adsorption and its compositional traits (characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectrum and Inductively coupled plasma-optical emission spectrometry). Possible improvement in PM removal was also evaluated by a detail whole city tree census and different scenarios of species adjustment data. We found that: 1) the amount of PM on juniper leaves was 5.73 g m−2, 2–2.5-fold higher than black pine and spruce (p < 0.05). Of them, 38.73%, 38.22%, and 23.11% were in the wax layer. 2) Compared with the explicit interspecies differences in PM quantity, more complex interspecies difference showed different patterns for different compositional traits. In general, leaf surface PM had higher O, Si, Al, Fe, N, Pb, Cu, Ni, Cr, and Cd, while the wax PM had higher C and Na contents (p < 0.05). 3) Association ordination found that the smaller leaf size, lower leaf water content, higher leaf area per unit mass, higher wax content, and larger stomatal openness aligned with the more PM adsorption by leaf, together with the higher amounts of CO stretching, O, Si, Al, N, heavy metals of Pb, Cu, Ni, Cr, and Cd in PM. 4) Compared with the other 2 species, increase of juniper percentage in urban forests is more effective for maximizing PM removal from air, accompanying more heavy metal removal but less crystalized minerals in PM. Our findings highlight that proper species configuration in urban afforestation could maximize the air PM removal capacity.

The concentration and speciation of heavy metals (Cu, Co, Ni, Zn, Cr, Pb and Cd) were studied in surface sediment from the Yangtze River(YR)to the East China Sea (ECS) shelf. The results showed that high contents of metals were found in the YR estuary (YRE) and in the nearshore muddy area, while lower concentrations were found in the YR channel and the ECS shelf. However, after standardization, the total content of most heavy metals from the YR showed little change or slightly increased during the transport process from the river to the estuary but decreased significantly outside the estuary, especially in the sediments of the ECS shelf. The residual fraction is the dominant fraction for all the metals, while the oxidizable and reducible fractions are the most important forms of the nonlithogenic fractions. The total amount of heavy metals from the YR to the continental shelf is mainly affected by the filtration of the estuary and the barrier impacts of the coastal current in the ECS. The environmental physicochemical conditions that vary significantly in the turbidity zone greatly influence the associated forms of metals. The metals in the acid-soluble fraction are mostly affected by the pH change in the sediment and the discharge of human activities, while the reducible fraction is significantly affected by the bottom water DO. The oxidizable fraction was affected by oxidation-reduction potential (ORP), primary productivity, as well as OM content. Therefore, with changes in the physicochemical conditions of the environment, the metals have undergone significant changes in their speciation from the YR to the ECS shelf. Various complex effects in the estuary area have not only a large filtration effect on the total amount of metals but also a major impact on the geochemical forms of the metals.