We conducted multiday continuous monitoring of indoor and outdoor particulate matter (PM) in classrooms with fan-assisted natural ventilation (NV) at five primary schools in Singapore. We monitored size-resolved number concentration of PM with diameter 0.3–10 μm at all schools and alveolar deposited surface area concentrations of PM with diameter 0.01–1.0 μm (SA₀.₀₁–₁.₀) at two schools. Results show that, during the monitoring period, schools closer to expressways and in the downtown area had 2–3 times higher outdoor PM₀.₃–₁.₀ number concentrations than schools located in suburban areas. Average indoor SA₀.₀₁–₁.₀ was 115–118 μm² cm⁻³ during periods of occupancy and 72–87 μm² cm⁻³ during unoccupied periods. There were close indoor and outdoor correlations for fine PM during both occupied and unoccupied periods (Pearson’s r = 0.84–1.0) while the correlations for coarse PM were weak during the occupied periods (r = 0.13–0.74). Across all the schools, the size-resolved indoor/outdoor PM ratios (I/O ratios) were 0.81 to 1.58 and 0.61 to 0.95 during occupied and unoccupied periods, respectively, and average infiltration factors were 0.64 to 0.94. Average PM net emission rates, calculated during periods of occupancy in the classrooms, were lower than or in the lower range of emission rates reported in the literature. This study also reveals that indoor fine and submicron PM predominantly come from outdoor sources, while indoor sources associated with occupancy may be important for coarse PM even when the classrooms have high air exchange rates.

This study characterizes a biotensoactive produced by the bacterium Azospirillum lipoferum, which was isolated from the rhizospheres of contaminated plants with oil in the lower basin of the Tonala River, Villa Benito Juarez, municipality of Cardenas, Tabasco, Mexico. The following properties were analyzed: viscosity at 25 °C, elemental analysis (% mol) by scanning electron microscopy, density at different temperatures, molecular weight, acute toxicity, median lethal concentration (LC₅₀), and saponification and acidity indices. The effects of pH (6.0, 7.0, 8.0, and 9.0) and temperature (25, 30, 35, and 40 °C) on the production of the biotensoactive and the effect of NaCl on the surface tension, density, and emulsifying capacity were studied. The results showed that the viscosity remained stable between 1.0914 and 1.1276 mPa-s, so the biotensoactive was classified as low-molecular weight. Toxic effects on the population of Eisenia foetida began at surfactant concentrations above 55,000 ppm, and the LC₅₀ was 96,695 ppm. The highest yield of biotensoactive production was obtained 48 h after the beginning of the treatment at pH 8 and pH 9 and 25 °C. At 25 °C, the surface tension ranged from 44.60 mN/m at a 1 % concentration by weight of NaCl to 51.11 mN/m at 15 % NaCl, while at 60 °C, the surface tension ranged from 34.90 mN/m at 1 % NaCl to 40.22 mN/m at 15 % NaCl. The emulsifying capacity was 70 % (aqueous solution 15 % NaCl).

The spread of antimicrobial resistance (AMR) is a global concern, high research priority being given to the environmental contamination, as the prevalence of organisms exhibiting AMR continues to increase. Multiresistant bacteria carrying different mobile genetic elements have been detected in sites with different degrees of urbanization, surface waters receiving insufficiently treated effluents being at high risk. The aim of the present study was to investigate the loads, antibiotic susceptibility, and class 1 integron carriage of Enterobacteriaceae isolated from surface waters and wastewaters around a large Romanian city. Searching for a valuable genetic marker of the displayed antibiotic resistance, the link between the AMR and the presence of int1I gene was explored in a total of 166 waterborne strains. Overall, amoxicillin-clavulanate resistance displayed the highest frequency (71.1 %), followed by ampicillin (63.9 %), cefuroxime (21.1 %), ciprofloxacin (17.5 %), cefotaxime (15.7 %), ceftriaxone (10.8 %), and gentamicin (6.6 %). The frequencies of isolates resistant to ampicillin, amoxicillin-clavulanate, ciprofloxacin, and gentamicin and also the prevalence of multiresistant strains were greater in surface waters, compared to wastewaters. The Int1I gene was detected in 21.7 % waterborne Enterobacteriaceae. A decrease in coliform counts and intI1-bearing cells, but a general increase in AMR and multiresistant bacteria, occurred during the wastewater treatment. A weak positive correlation was found between multidrug resistance int1I carriage in wastewater effluent but no sufficient evidence of a linkage between phenotypic AMR and int1I, overall. The presence of class 1 integron can be associated with anthropogenic influence, but the simple detection of intI1 gene cannot explain the complex antibiotic resistance phenotype.

Radionuclides were determined in streams and rivers receiving mine drainage from old uranium mines at the center of Portugal. Results showed enhanced radioactivity levels in some areas impacted by uranium mining and milling wastes, but levels were lower than several years ago due to current water treatment of mine drainage. In some areas, such as at the village of Cunha Baixa, water from wells was contaminated by acid mine drainage, and it is not suitable anymore for human consumption and irrigation of horticulture plots. In the present, villages and towns near those old uranium mines have tap water from public networks supplied from artificial lakes built in major rivers of the region. This tap water showed compliance with the recommended limits of total alpha and total beta radioactivity, and it is suitable for human consumption. Radiation exposure of the population was therefore controlled, but current water supply is much more costly than it was with local water sources.

The bulk deposition of both PAHs and metals is a significant, mounting issue for the urban ecological environment. However, studies generally performed on these pollutants have focused on the regions surrounding a pollution source; thus, it most likely overestimated pollutants in the cities. Therefore, 72 atmospheric bulk deposition samples were collected from six sites located along a transect from the suburbs to the city center in Shanghai over a 1-year period (February 1, 2012 to January 31, 2013). The seasonal variation, spatial distribution, and sources of multiple metals (Al, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, Pb, K, Na, and Mg) and 16 polycyclic aromatic hydrocarbon (PAH) compounds were determined. The results indicated that the annual average rate of dust deposition in Shanghai was 43,100 ± 54,800 mg/m²/year. There were significant or high enrichments of Cu, Zn, Cd, and Pb, and higher depositional fluxes were observed for Zn, Pb, and Cd in the Huangpu district and for Cu in the Minhang district. The deposition fluxes of the PAHs exhibited the following order: urban fringe zone > city center > rural zone (background site). However, unlike in northern Chinese cities, the high-molecular-weight PAHs accounted for most of the PAHs. Furthermore, there were higher depositional fluxes of PAHs in March, July, and October. Overall, the factors influencing urban air quality may include construction, fossil fuel combustion, the abrasion of tires and brake linings (directly related to traffic), the corrosion of galvanized protection barriers, and increasing population density.

The effects of soil micro-particles and micro-pores on the release of total petroleum hydrocarbons (TPH) were investigated using long-term weathered, TPH-contaminated soil samples. The TPH concentrations were analyzed using various extraction schemes (i.e., total extraction, weak extraction, solvent extraction with or without ultrasound). The particle size distribution (<2 mm, 0.063–2 mm, <0.063 mm), micro-pore volume (<0.38 mm), and TPH fraction (C8–14, C16–28, C30–40) of selected samples were also determined to better understand the factors controlling TPH release from contaminated soils. TPH concentrations varied greatly among different fractions of each soil sample, but were highest in the micro-fraction (<0.063 mm) of each sample. In weathered soil samples, TPH was not only weakly or strongly adsorbed on soil particles, but also trapped in soil micro-pores. Moreover, heavier fractions of TPH were released slowly and lesser extent from contaminated soils. Results showed that the solvent extraction method with and without ultrasound could be used to assess relative binding strength of TPH to contaminated soils. These findings imply that to achieve a remediation goal, some contaminated soils require only relatively mild extraction with solvent, but soils with TPH trapped in micro-pores require physical destruction along with chemical extraction.

Currently, there are increasing efforts to utilize nanoremediation as an environmental technology for cleaning up polluted environments using nanoscale zero-valent iron (nZVI); however, concerns exist regarding the long-term environmental impact of this strategy. In this study, an innovative methodology for evaluating nZVI impact on soil bacteria is utilized, based on transcriptional analysis of three novel biomakers: tnaA, sodB and trx genes. At the same time, classical toxicological bioassays with the nematode Caenorhabditis elegans were performed. Microcosms treated with 1, 5 and 10 % w/w of nZVI were set up using a commercial standard soil and incubated for 21 days. The tnaA gene, involved in indole production, was significantly upregulated at all assessed nZVI concentrations, suggesting that bacterial cells used this molecule to inform the rest of the community about the changes produced upon nZVI soil treatment. The higher the exposure time, the lower nZVI concentration needed to detect these changes. Consequently, soil bacteria activate a cellular adaptive response to cope with the nZVI-induced oxidative stress, increasing the expression of genes encoding key reactive oxygen species (ROS)-scavenging enzymes; in fact, an upregulation of the sodB and katB genes was recorded upon nZVI exposure. On the contrary, C. elegans survival and growth endpoints were not affected at any nZVI concentration whereas the exposure time significantly increased nematode growth in the soil. Therefore, despite the lack of toxicity revealed by the classical conducted tests, the transcriptional analyses demonstrated the usefulness of combining the set of proposed biomarkers for early detection and monitoring the impact of nZVI on soil bacteria after environmentally important periods of exposure.

In the presented in vitro experiment, the effect of selenite treatment (0.01, 0.1, 1, 10 and 50 mg L⁻¹ Se(IV)) on Berula erecta was investigated with respect to growth, photochemical efficiency, photosynthetic pigments, anthocyanins and low molecular weight thiols. Lower Se(IV) concentrations (0.01, 0.1 and 1 mg L⁻¹) promoted growth, while higher Se(IV) concentrations (10 and 50 mg L⁻¹) negatively affected it. The photochemical efficiency of photosystem II decreased significantly in plants treated with higher Se(IV) concentrations, compared to that in the control plants. The content of pigments decreased in all the Se(IV) treatments. Both cysteine and glutathione showed alterations in their content and redox state depending on the Se concentration. By evaluating the glutathione/cysteine system and their redox, it was possible to identify a threshold Se content (1-mg Se(IV) L⁻¹ treatment), above which the nature of the effects induced changes from antioxidant to pro-oxidant.

Co-digestion of swine manure and crude glycerine from biodiesel production has been successfully attempted by many authors reporting substantial increments in biogas production. However, the effectiveness of this approach has been questioned recently. The addition of glycerol may cause an improvement in biogas production but at the expense of disturbing the degradation of manure. In the present paper, the organic transformations undergone in the anaerobic digestion of pig manure at increasing amounts of glycerine (2–8 % (v/v)) were analysed using spectroscopy techniques (Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (¹H NMR)). An increase in biogas production was observed with the addition of glycerine up to 8 %, resulting in a volumetric production of methane per litre of reactor (Lr) of 1.4 L CH₄/Lr d. However, the subsequent failure of the system was observed at this glycerine content due to the inhibitory effect caused by high H₂S concentration and foam formation. FTIR and ¹H NMR analysis performed on digestate samples showed that the addition of the co-substrate also caused the preferential degradation of glycerine and accumulation of proteins and aliphatic compounds. A post-stabilisation stage was necessary to complete the degradation process. Modifications in organic matter continued under this last stage although in the previous digestion period, a competition for substrate between sulphate reducing bacteria and methanogens was observed.

Present technologies for wastewater treatment do not sufficiently address the increasing pollution situation of receiving water bodies, especially with the growing use of personal care products and pharmaceuticals (PPCP) in the private household and health sector. The relevance of addressing this problem of organic pollutants was taken into account by the Directive 2013/39/EU that introduced (i) the quality evaluation of aquatic compartments, (ii) the polluter pays principle, (iii) the need for innovative and affordable wastewater treatment technologies, and (iv) the identification of pollution causes including a list of principal compounds to be monitored. In addition, a watch list of 10 other substances was recently defined by Decision 2015/495 on March 20, 2015. This list contains, among several recalcitrant chemicals, the painkiller diclofenac and the hormones 17β-estradiol and 17α-ethinylestradiol. Although some modern approaches for their removal exist, such as advanced oxidation processes (AOPs), retrofitting most wastewater treatment plants with AOPs will not be acceptable as consistent investment at reasonable operational cost. Additionally, by-product and transformation product formation has to be considered. The same is true for membrane-based technologies (nanofiltration, reversed osmosis) despite of the incredible progress that has been made during recent years, because these systems lead to higher operation costs (mainly due to higher energy consumption) so that the majority of communities will not easily accept them. Advanced technologies in wastewater treatment like membrane bioreactors (MBR) that integrate biological degradation of organic matter with membrane filtration have proven a more complete elimination of emerging pollutants in a rather cost- and labor-intensive technology. Still, most of the presently applied methods are incapable of removing critical compounds completely. In this opinion paper, the state of the art of European WWTPs is reflected, and capacities of single methods are described. Furthermore, the need for analytical standards, risk assessment, and economic planning is stressed. The survey results in the conclusion that combinations of different conventional and advanced technologies including biological and plant-based strategies seem to be most promising to solve the burning problem of polluting our environment with hazardous emerging xenobiotics.