The occurrence of magnetotactic bacteria (MTB) on a Tunisian marine coast exposed to heavy metals pollution (Sfax, Gulf of Gabès, Mediterranean Sea) was investigated. The MTB population of this Southern Mediterranean coast was compared to the MTB populations previously investigated on the French Northern Mediterranean coast. A dominant MTB coccus morphotype was observed by microscopy analysis. By pyrosequencing technology, the analysis of the 16S ribosomal RNA (rDNA) revealed as much as 33 operational taxonomic sequence units (OTUs) close to sequences of MTB accessible in the databases. The majority were close to MTB sequences of the “Med group” of α-Proteobacteria. Among them, a dominant OTU_001 (99 % of the MTB sequences) affiliated within the Magnetococcales order was highlighted. Investigating the capacities of this novel bacterium to be used in bioremediation and/or depollution processes could be envisaged.

A comprehensive approach has been developed to the assessment of composition and properties of atmospherically deposited dust in the area affected by a copper smelter. The approach is based on the analysis of initial dust samples, dynamic leaching of water soluble fractions in a rotating coiled column (RCC) followed by the determination of recovered elements and characterization of size, morphology and elemental composition of nano-, submicron, and micron particles of dust separated using field-flow fractionation in a RCC. Three separated size fractions of dust (<0.2, 0.2–2, and >2 μm) were characterized by static light scattering and scanning electron microscopy, whereupon the fractions were analyzed by ICP-AES and ICP-MS (after digestion). It has been evaluated that toxic elements, which are characteristics for copper smelter emissions (As, Cu, Zn), are accumulated in fraction >2 μm. At the same time, up to 2.4, 3.1, 8.2, 6.7 g/kg of As, Cu, Zn, Pb, correspondently, were found in nanoparticles (<0.2 μm). It has been also shown that some trace elements (Sn, Sb, Ag, Bi, and Tl) are accumulated in fraction <0.2, and their content in this fraction may be one order of magnitude higher than that in the fraction >2 μm, or the bulk sample. It may be assumed that Sn, Sb, Ag, Bi, Tl compounds are adsorbed onto the finest dust particles as compared to As, Cu, Zn compounds, which are directly emitted from the copper smelter as microparticles.

Aerosol composition and properties variation under the advection of different air masses were investigated, as case studies, by contemporary measurements over the atmospheric column and at the ground in a semi-rural site in South Italy. The absence of local strong sources in this area allowed to characterize background aerosol and to compare particle mixing effects under various atmospheric circulation conditions. Aerosol optical depth (AOD) and Ǻngström parameters from radiometric measurements allowed the detection and identification of polluted, dust, and volcanic atmospheric conditions. AODs were the input for a suitable model to evaluate the columnar aerosol composition, according to six main tmospheric components (water-soluble, soot, sea salt accumulation, sea salt coarse, mineral dus,t and biological). Scanning electron microscope (SEM) analysis of particulate sampled with a 13-stage impactor at the ground showed not only fingerprints typical of the different air masses but also the effects of transport and aging on atmospheric particles, suggesting processes that changed their chemical and optical properties. Background columnar aerosol was characterized by 72 % of water-soluble and soot, in agreement with ground-based findings that highlighted 60 % of contribution from anthropogenic carbonate particles and soot. In general, a good agreement between ground-based and columnar results was observed. Under the advection of trans-boundary air masses, water-soluble and soot were always present in columnar aerosol, whereas, in variable percentages, sea salt and mineral particles characterized both dust and volcanic conditions. At the ground, sulfates characterized the amorphous matrix produced in finer stages by the evaporation of solutions of organic and inorganic aerosols. Sulfates were also one of the key players involved in heterogeneous chemical reactions, producing complex secondary aerosol, as such clay-sulfate internally mixed particle externally mixed with soot chains.

A 9-year water dataset from the Houston Ship Channel (HSC) was analyzed to understand partitioning in polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/Fs). Total PCBs had more mass as dissolved (74 %) whereas total PCDD/Fs did not (11 %). Generally, the limited number of PCDD/Fs (only 2378 substituted) explained these differences though differences in chemical behavior beyond log K ₒw also likely influence partitioning. The particular fractionation seen in the HSC also seemed related to a wide variation in particulate organic carbon (POC)/dissolved organic carbon (DOC) ratio (0.42–180 %). Published and unaltered linear free energy and linear solvation energy relationships for DOC, POC, and particulate black carbon (BC) resulted in predictions that were at best 27 % (PCB) and 25 % root-mean-square error (RMSE) (PCDD/F) partition fraction compared to observed (using estimated BC/POC fractions of 10 and 25 %, respectively). These results show, at least in light of the uncertainties in this data (e.g., precise fraction of BC), that a 25 % accuracy in model prediction of operationally dissolved or suspended fraction for any one PCB or PCDD/F congener is the best prediction that may be expected. It is therefore recommended that site-specific data be used to calibrate most any water column-partitioning model if it is to be expected to describe what actually occurs in field conditions.

Mercury contents in soil and olive tree leaves have been studied in 69 plots around three different source areas of this element in Spain: Almadén (Ciudad Real), Flix (Tarragona) and Jódar (Jaén). Almadén was the world’s largest cinnabar (HgS) mining district and was active until 2003, Flix is the oldest Spanish chlor-alkali plant (CAP) and has been active from 1898 to the present day and Jódar is a decommissioned CAP that was active for 14 years (1977–1991). Total mercury contents have been measured by high-frequency modulation atomic absorption spectrometry with Zeeman effect (ZAAS-HFM) in the soils and olive tree leaves from the three studied areas. The average soil contents range from 182 μg kg⁻¹ in Flix to 23,488 μg kg⁻¹ in Almadén, while the average leaf content ranges from 161 μg kg⁻¹ in Jódar to 1213 μg kg⁻¹ in Almadén. Despite the wide range of data, a relationship between soil–leaf contents has been identified: in Almadén and Jódar, multiplicative (bilogarithmic) models show significant correlations (R = 0.769 and R = 0.484, respectively). Significant correlations were not identified between soil and leaf contents in Flix. The continuous activity of the Flix CAP, which remains open today, can explain the different uptake patterns for mercury, which is mainly atmospheric in origin, in comparison to the other two sites, where activity ceased more than 10 years ago and only soil uptake patterns based on the Michaelis–Menten enzymatic model curve are observed.

The composition, seasonal variation, and potential sources of sulfate (S) and nitrogen (N) deposition in precipitation in the southwest of China from 2003 to 2013 were investigated. The results showed that the concentration of SO₄²⁻, NO₃⁻, and NH₄⁺ in rainwater were 10.57–1360, 7.16–523.71, and 7.54-1020 μeq l⁻¹, with an annual volume-weighted mean (VWM) concentration of 103.99, 46.73, and 97.30 μeq l⁻¹, respectively. The annual wet deposition of SO₄²⁻, NO₃⁻, and NH₄⁺ was 21.66, 8.16, and 17.49 kg S (N) ha⁻¹, respectively. The temporal variations of the ions showed that the abrupt decreasing breakpoints were in 2008 for SO₄²⁻ and in 2009 for NO₃⁻ and NH₄⁺, and increasing trends were observed after 2010 for the three ions. These trends reflected the effect of economy recession and the policy of controlling SO₂ and NOₓ emissions. The acid rain type of precipitation was shifted from sulfur to a mixed one. The ions of SO₄²⁻, NO₃⁻, and NH₄⁺ presented high values in winter and spring and low values in autumn and summer. A highly positive linear correlation between SO₄²⁻ and NO₃⁻ (R ² = 0.71), SO₄²⁻ and NH₄⁺ (R ² = 0.74), and NO₃⁻ and NH₄⁺ (R ² = 0.84) existed while a strong negative correlation was found between the three main ionic concentrations and precipitation. The SO₄²⁻ was mainly from fossil fuel combustion (60.53 %), aged sea salt (19.03 %), agriculture (11.38 %), crust (6.66 %), and biomass burning (2.40 %); the NO₃⁻ was mainly from fossil fuel combustion (75.41 %), biomass burning (9.67 %), aged sea salt (7.97 %), and agriculture (6.96 %); and the NH₄⁺ was mainly from agriculture (86.38 %), fossil fuel combustion (10.52 %), and aged sea salt (3.09 %).

Zinc oxide (ZnO) nanoparticles were synthesized by precipitation and sol-gel methods. The aim of this study was to understand how different synthetic methods can affect the photocatalytic activity of ZnO nanoparticles. As-synthesized ZnO nanoparticles were characterized by X-ray diffraction (XRD) and UV-Visible spectroscopic techniques. XRD patterns of ZnO powders synthesized by precipitation and sol-gel methods revealed their hexagonal wurtzite structure with crystallite sizes of 30 and 28 nm, respectively. Their photocatalytic activities were evaluated by photocatalytic degradation of methylene blue, a common water pollutant, under UV radiation. The effects of operational parameters such as photocatalyst load and initial concentration of the dye on photocatalytic degradation of methylene blue were investigated. While the degradation of dye decreased over the studied dye concentration range of 20 to 100 mg/L, an optimum photocatalyst load of 250 mg/L was needed to achieve dye degradation as high as 81 and 92.5 % for ZnO prepared by precipitation and sol-gel methods, respectively. Assuming pseudo first-order reaction kinetics, this corresponded to rate constants of 8.4 × 10⁻³ and 12.4 × 10⁻³ min⁻¹, respectively. Hence, sol-gel method is preferred over precipitation method in order to achieve higher photocatalytic activity of ZnO nanostructures. Photocatalytic activity is further augmented by better choice of capping ligand for colloidal stabilization, starch being more effective than polyethylene glycol (PEG).

The nitrogen cycle has been expanded with the recent discovery of Nitrospira strains that can conduct complete ammonium oxidation (commamox). Their importance in the nitrogen cycle within engineered ecosystems has not yet been analyzed. In this research, the community structure of the Bacteria domain of six full-scale activated sludge systems and three autotrophic nitrogen removal systems in the Netherlands and China has been investigated through tag-454-pyrosequencing. The phylogenetic analyses conducted in the present study showed that just a few of the Nitrospira sequences found in the bioreactors were comammox. Multivariate redundancy analysis of nitrifying genera showed an outcompetition of Nitrosomonas and non-comammox Nitrospira. Operational data from the bioreactors suggested that comammox could be favored at low temperature, low nitrogen substrate, and high dissolved oxygen. The non-ubiquity and low relative abundance of comammox in full-scale bioreactors suggested that this phylotype is not very relevant in the nitrogen cycle in wastewater treatment plants.

The purpose of the study was to evaluate the phytoremediation potentiality of a herb named Crotalaria pallida which are abundantly grown on crude oil-contaminated soil of oil field situated at upper Assam, India, so that this plant could be used to remediate hydrocarbon from contaminated soil. To evaluate the potentiality of the plant, a pot culture experiment was conducted taking 3 kg of rice field soil mixed with crude oil at a concentration of 10,000 (10 g/kg), 20,000 (20 g/kg), 30,000 (30 g/kg), 40,000 (40 g/kg), 50,000 (50 g/kg), 60,000 (60 g/kg), 70,000 (70 g/kg), 80,000 (80 g/kg), 90,000 (90 g/kg), and 100,000 (100 g/kg) ppm. Ten numbers of healthy seeds of C. pallida were sown in three pots of each concentration for germination, and after 15 days of germination, single healthy seedling in each pot was kept for the study. A control setup was also maintained without adding crude oil. The duration of the experiment was fixed for 6 months. The results showed that uptake of hydrocarbon by the plants was increased with increasing the concentration of crude oil in the soil up to 60,000 ppm. After that, uptake of hydrocarbon by the plants was found to be lower with increasing doses of crude oil concentration. Uptake of hydrocarbon by the shoot was found to be maximum, i.e., 35,018 ppm in 60,000 ppm concentration. Dissipation of total petroleum hydrocarbon (TPH) from the soil was also gradually increased with increasing concentration of crude oil in the soil up to 60,000 ppm. Maximum dissipation, i.e., 78.66 %, occurred in 60,000 ppm concentration of crude oil-mixed soil. The plant could not survive in 100,000 ppm concentration of crude oil-mixed soil. The results also demonstrated that there was a reduction in plant shoot and root biomass with an increase of crude oil concentration. Furthermore, results revealed that the shoot biomass was higher than root biomass in all the treatments.

In this study, we investigated the impact of potential emission sources and transport pathways on annual and seasonal PM₁₀ loadings in an urban area of Belgrade (Serbia). The analyzed dataset comprised PM₁₀ mass concentrations for the period 2003–2015, as well as their chemical composition (organic/elemental carbon, benzo[a]pyrene, As, Cd, Cr, Mn, Ni, Pb, Cl⁻, Na⁺, Mg²⁺, Ca²⁺, K⁺, NO₃⁻, SO₄²⁻, and NH₄⁺), meteorological parameters, and concentrations of inorganic gaseous pollutants and soot for the period 2011–2015. The combination of different methods, such as source apportionment (Unmix), ensemble learning method (random forest), and multifractal and inverse multifractal analysis, was utilized in order to obtain a detailed description of the PM₁₀ origin and spatio-temporal distribution and to determine their relationship with other pollutants and meteorological parameters. The contribution of long-range and regional transport was estimated by means of trajectory sector analysis, whereas the hybrid receptor models were applied to identify potential areas of concern.