This article deals with the state-of-the-art of experimental and numerical studies carried out regarding air pollutant dispersion in urban environments. Since the simulation of the dispersion field around buildings depends strongly on the correct simulation of the wind-flow structure, the studies performed during the past years on the wind-flow field around buildings are reviewed. This work also identifies errors that can produce poor results when numerically modelling wind flow and dispersion fields around buildings in urban environments. Finally, particular attention is paid to the practical guidelines developed by researchers to establish a common methodology for verification and validation of numerical simulations and/or to assist and support the users for a better implementation of the computational fluid dynamics (CFD) approach.

Although water-dispersible engineered nanoparticles (ENPs) have a wide range of applications, the ENPs used in many nanotoxicological studies tend to form micron-sized aggregates in the exposure media and thus cannot reflect the toxicity of real nanoparticles. Here we described the synthesis of bare hematite nanoparticles (HNPs-0) and two poly(acrylic acid) (PAA)-coated forms (HNPs-1 and HNPs-2). All three HNPs were well dispersed in deionized water, but HNPs-0 quickly aggregated in the three culture media tested. By contrast, the suspensions of HNPs-1 and HNPs-2 remained stable, with negligible amounts of PAA and Fe3+ liberated from either one under the investigated conditions. To better quantify the accumulation of the coated HNPs, a relatively innocuous 55Fe-labeled form of HNPs-2 was synthesized as an example and its accumulation in three phytoplankton species was tested. Consistent with the uptake kinetics model for conventional pollutants, the cellular accumulation of HNPs-2 increased linearly with exposure time for two of the three phytoplankton species. These results demonstrate the utility of 55Fe-labeled well-dispersible HNPs as a model material for nanoparticle bioaccumulation studies in nanotoxicology.

With the development of society and the economy, many Chinese cities are shrouded in pollution haze for much of the year. Scientific studies have identified various adverse effects of air pollutants on human beings. However, the relationships between air pollution and blood lipid levels are still unclear. The objective of this study is to explore the short and long-term effects of air pollution on eight blood lipid markers among elderly hypertension inpatients complicated with or without type 2 diabetes (T2D). Blood lipid markers which met the pre-established inclusion criteria were exported from the medical record system. Air pollution data were acquired from the official environmental protection website. Associations between the air quality index and the blood lipid indexes were analyzed by one-way ANOVA and further Bonferroni correction. In an exposure time of 7 days or longer, blood lipid markers were somewhat affected by poor air quality. However, the results could not predict whether atherosclerosis would be promoted or inhibited by poorer air condition. Changes of blood lipid markers of hypertension inpatients with or without T2D were not completely the same, but no blood lipid markers had an opposite trend between the two populations. The air quality index was associated with changes to blood lipid markers to some extent in a population of hypertension inpatients with or without T2D. Further studies are needed to investigate the potential mechanism by which air pollutants induce blood lipids changes.

Long-term air monitoring data for POPs are required to determine the effectiveness of source reduction measures and factors controlling air concentrations. Air samples were collected between 1992 and 2012 at three sites with different geographical characteristics (Burnt Island, Egbert and Point Petre) in the Canadian Great Lakes Basin (GLB) using high-volume samplers and analyzed for organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). Spatial and temporal trends of gas-phase concentrations of OCPs, selected PCB congeners and ƩPCBs (84 congeners) were assessed. Egbert had the highest concentrations of some OCPs due to historical [dichlorodiphenyltrichloroethanes (DDTs), dieldrin, γ-hexachlorocyclohexane (γ-HCH)] and current (endosulfan) applications of these pesticides in the surrounding agricultural cropland. This shows that agricultural areas are a source of OCPs to the GLB. High o,p'-/p,p'-DDT ratios were determined and an increasing trend was observed at Point Petre and Burnt Island up to 2004; indicating that the GLB is influenced by dicofol-type DDT sources, which have higher o,p’-/p,p’-DDT ratios than technical DDT. Atmospheric PCB concentrations at Egbert and Point Petre are higher than those measured at Burnt Island, likely due to urban influence and greater populations. Loadings calculations suggest that the atmosphere is a source of α-endosulfan and p,p’-DDT to the lakes and the opposite is true for p,p’-DDE. Long-term decreasing trends were observed for both OCPs and PCBs; consistent with control measures implemented in North America. Atmospheric PCB concentrations are decreasing relatively slowly, with halflives in the range of 9–39 years. Chlordane, α-endosulfan, β-endosulfan, dieldrin, and DDT-related substances showed halflives in the range of 7–13 years. α-HCH and γ-HCH were decreasing rapidly in air, with halflives of 5 years. Long-term declining trends of PCBs and OCPs suggest that regulatory efforts to reduce emissions to the GLB environment have been effective, but emissions from primary and secondary sources might limit future declines.

Metals and metalloids are natural components of the biosphere, which are not produced per se by human beings, but whose form and distribution can be affected by human activities. Like all substances, they are a contaminant if present in excess compared to background levels and/or in a form that would not normally occur in the environment. Samples of liver, gills, gonads and muscle from European chub, Squalius cephalus, were analyzed for Al, As, B, Ba, Cr, Cu, Fe, Hg, Mn, Mo, Sr and Zn using inductively coupled plasma optical emission spectrometry (ICP-OES) to highlight the importance of tissue selection in monitoring research. The comet assay or single cell gel electrophoresis (SCGE) was selected as an in vivo genotoxicity assay, a rapid and sensitive method for measuring genotoxic effects in blood, liver and gills of the European chub. Microscopic images of comets were scored using Comet IV Computer Software (Perceptive Instruments, UK).The objective of our study was to investigate two reservoirs, Zlatar and Garasi, and one river, Pestan by: (i) determining and comparing metal and metalloid concentrations in sediment, water and tissues of European chub: liver, gills, muscle and gonads (ii) comparing these findings with genotoxicity of water expressed through DNA damage of fish tissues.A clear link between the level of metals in water, sediment and tissues and between metal and genotoxicity levels at examined sites was not found. This suggests that other xenobiotics (possibly the organic compounds), contribute to DNA damage.

Biochar is a porous carbonaceous material with high alkalinity and rich minerals, making it possible for CO2 capture. In this study, biochars derived from pig manure, sewage sludge, and wheat straw were evaluated for their CO2 sorption behavior. All three biochars showed high sorption abilities for CO2, with the maximum capacities reaching 18.2–34.4 mg g−1 at 25 °C. Elevating sorption temperature and moisture content promoted the transition of CO2 uptake from physical to chemical process. Mineral components such as Mg, Ca, Fe, K, etc. in biochar induced the chemical sorption of CO2 via the mineralogical reactions which occupied 17.7%–50.9% of the total sorption. FeOOH in sewage sludge biochar was transformed by sorbed CO2 into Fe(OH)2CO3, while the sorbed CO2 in pig manure biochar was precipitated as K2Ca(CO3)2 and CaMg(CO3)2, which resulted in a dominant increase of insoluble inorganic carbon in both biochars. For wheat straw biochar, sorbed CO2 induced CaCO3 transformed into soluble Ca(HCO3)2, which led to a dominant increase of soluble inorganic carbons. The results obtained from this study demonstrated that biochar as a unique carbonaceous material could distinctly be a promising sorbent for CO2 capture in which chemical sorption induced by mineralogical reactions played an important role.

This study focused on the combined effect of environmental conditions (temperature) and contamination (polycyclic aromatic hydrocarbons, PAHs) on the activity of soil microorganisms (nitrifying bacteria). Phenanthrene (Phe) at five contamination levels (0, 1, 10, 100 and 1000 mg kg−1 dry mass of soil) was employed as a model PAH compound in laboratory experiments that were conducted at three temperatures (i.e., 20 °C (recommended by ISO 15685 method), 15 and 30 °C). Three soils with different properties were used in these studies, and the activity of the nitrifying bacteria was assessed based on nitrification potential (NP) determinations. For the statistical evaluation of the results, the ANCOVA (analysis of covariance) method for three independent variables (i.e., temperature, phenanthrene concentration, soil matrix (as a qualitative variable)) and their interactions was employed. The results indicated on the significant interaction of all studied factors. Temperature influenced the toxicity of Phe towards NP, and this effect was related to the Phe concentration as well as was varied for the different soils. A low content of soil organic matter (controlling bioavailability of phenanthrene to soil microorganisms) enhanced the combined effect of temperature and Phe toxicity, and a high biological activity of the soil (high NP values) increased the effect of high temperature on the Phe stimulatory influence. The results indicate that the temperature should not be neglected in tests evaluating PAH ecotoxicity, especially for reliable ecological risk assessment.

From November 2014 to October 2015, the concentrations of volatile organic compounds (VOCs), O3 and NOx were simultaneously monitored by using online instruments at the air monitoring station belonged to Tianjin Environmental Protection Bureau (TEPB). The results indicated that VOCs concentrations were higher in autumn and lower in spring, while O3 concentrations were higher in summer, and lower in winter. The diurnal variations of VOCs and NOx (NO2 plus NO) showed opposite tendency comparing to that of O3. The concentrations of alkanes were higher (the average of 18.2 ppbv) than that of aromatics (5.3 ppbv) and alkenes (5.2 ppbv), however, the alkenes and aromatics made larger contributions to ozone because of their high reactivity. Tianjin belonged to the VOC-limited region during most of seasons (except summer) according to the VOC/NOx ratios (the 8:1 threshold). The automobile exhaust, industrial emission, liquefied petroleum gas/natural gas (LPG/NG), combustion, gasoline evaporation, internal combustion engine emission and solvent usage were identified as major sources of VOCs by Positive Matrix Factorization (PMF) model in Tianjin, and the contributions to VOCs for the entire year were 23.1%, 19.9%, 18.6%, 10.6%, 8.7%, 5.4% and 4.7%, respectively. The conditional probability function (CPF) analysis indicated that the contributing directions of automobile exhaust and industrial emission were mainly affected by source distributions, and that of other sources might be mainly affected by wind direction. The backward trajectory analysis indicated that the trajectory of air mass originated from Mongolia, which reflected the features of large-scale and long-distance air transport, and that of beginning in Jiangsu, Shandong and Tianjin, which showed the features of small-scale and short-distance. Tianjin, Beijing, Hebei and Northwest of Shandong were identified as major potential source-areas of VOCs by using potential source contribution function (PSCF) and concentration-weighted trajectory (CWT) models.

Understanding the evolution of aerosols in the atmosphere is of great importance for improving air quality and reducing aerosol-related uncertainties in global climate simulations. Here, a unique haze episode at a regional receptor site near the East China Sea was examined as a case study of the aging process of atmospheric aerosols during transport. An increase in photochemical age from 5 h to more than 25 h and a progressive increase in the fitted mean particle diameter from 70 nm to approximately 300 nm were observed. According to the pollution features and meteorology conditions involved, pollution accumulation (PA), sea breeze (SB), and land breeze (LB) periods were identified. Concentrations of black carbon (BC), hydrocarbon-like organic aerosols (HOA), semi-volatile oxidized organic aerosols (SV-OOA), and nitrate increased by 7-fold up to 39-fold when the air masses passed through Taizhou, a nearby city. In addition, nitrate and SV-OOA dominated the aerosol composition in the urban outflow plumes (52% and 18%, respectively), yet they gradually decreased in concentration during transport. In contrast, sulfate and the low-volatile oxidized organic aerosols (LV-OOA) exhibited more regional footprints and potentially have similar formation mechanisms. The atomic oxygen-to-carbon (O/C) ratio also increased from 0.45 to 0.9, thereby suggesting that rapid formation of highly oxidized secondary organic aerosols (SOA) occurred during transport. Overall, these results provide valuable insight into the evolution of the chemical and physical features of aerosol pollution during transport and also highlight the need for regulatory controls of nitrogen oxides, sulfur dioxide, and VOCs to improve air quality on different scales.

In the last decades a dramatic loss of Apis mellifera hives has been reported in both Europe and USA. Research in this field is oriented towards identifying a synergy of contributing factors, i.e. pathogens, pesticides, habitat loss and pollution to the weakening of the hive. Cadmium (Cd) is a hazardous anthropogenic pollutant whose effects are proving to be increasingly lethal. Among the multiple damages related to Cd contamination, some studies report that it causes immunosuppression in various animal species. The aim of this paper is to determine whether contamination by Cd, may have a similar effect on the honey bees’ immunocompetence. Our results, obtained by immune challenge experiments and confirmed by structural and ultrastructural observations show that such metal causes a reduction in immunocompetence in 3 days Cd exposed bees. As further evidence of honey bee response to Cd treatment, Energy Dispersive X-ray Spectroscopy (X-EDS) has revealed the presence of zinc (Zn) in peculiar electron-dense granules in fat body cells. Zn is a characteristic component of metallothioneins (MTs), which are usually synthesized as anti-oxidant and scavenger tools against Cd contamination. Our findings suggest that honey bee colonies may have a weakened immune system in Cd polluted areas, resulting in a decreased ability in dealing with pathogens.