In the study, observational data analyses and the WRF-CHEM model simulations are used to investigate the role of sea-land and mountain-valley breeze circulations in a severe air pollution event occurred in Beijing-Tianjin-Hebei (BTH) during August 9–10, 2013. Both the wind observations and the model simulations have clearly indicated the evolution of the sea-land and mountain-valley breeze circulations during the event. The WRF-CHEM model generally reproduces the local meteorological circulations and also performs well in simulating temporal variations and spatial distributions of fine particulate matters (PM₂.₅) and ozone (O₃) concentrations compared to observations in BTH. The model results have shown that the offshore land breeze transports the pollutants formed in Shandong province to the Bohai Gulf in the morning, causing the formation of high O₃ and PM₂.₅ concentrations over the gulf. The onshore sea breeze not only causes the formation of a convergence zone to induce upward movement, mitigating the surface pollution to some degree, also recirculates the pollutants over the gulf to deteriorate the air quality in the coastal area. The upward valley breeze brings the pollutants in the urban area of Beijing to the mountain area in the afternoon, and the downward mountain breeze transports the pollutants back during nighttime. The intensity of the mountain-valley breeze circulation is weak compared to the land-sea breeze circulation in BTH. It is worth noting that the local circulations play an important role when the large-scale meteorological conditions are relatively weak.

Major sources of petroleum hydrocarbons in the south of Caspian Sea (Anzali city) have been investigated through an approach which combines Gas Chromatography–Mass Spectrometry with Principal Component Analysis (PCA) and Multivariate Curve Resolution-Alternating Least Squares chemometric methods. Terpane, catagenetic hopane and sterane hydrocarbons were analyzed in the street dust, filtered sediments of runoff, soluble runoff water and river sediment samples as well as in automobiles exhaust, tires, asphalt, engine oil, gasoline and diesel samples, as possible sources of these hydrocarbons. PCA and MCR-ALS results showed that a large part of the analyzed hydrocarbons in street dust, runoffs and in some of the river sediment samples can be explained by the proposed known sources, while the observed variation of hydrocarbon concentrations in many of the river sediment samples was not much affected by the proposed known sources, and they were most probably receiving other pollution sources not included in our study. This study also has shown that results obtained from hydrocarbon marker molecular ratios, to identify petroleum pollution sources in the environments, are in agreement with those obtained from pollution sources resolved by MCR-ALS simultaneous analysis of all samples and variables.

Tetracyclines are a class of antimicrobials frequently found in the environment, and have promoted the proliferation of antibiotic resistance. An unanswered research question is whether tetracycline sorbed to soils is still bioavailable to bacteria and exerts selective pressure on the bacterial community for the development of antibiotic resistance. In this study, bioreporter E. coli MC4100/pTGM strain was used to probe the bioavailability of tetracycline sorbed by smectite clay, a class of common soil minerals. Batch sorption experiments were conducted to prepare clay samples with a wide range of sorbed tetracycline concentration. The bioreporter was incubated with tetracycline-sorbed clay at different clay/solution ratios and water contents, as well as using dialysis tubings to prevent the direct contact between bacterial cells and clay particles. The expression of antibiotic resistance genes from the bioreporter was measured using a flow cytometer as a measurement of bioavailability/selective pressure. The direct contact of bioreporter cells to clay surfaces represented an important pathway facilitating bacterial access to clay-sorbed tetracycline. In clay-water suspensions, reducing solution volume rendered more bacteria to attach to clay surfaces enhancing the bioavailability of clay-sorbed tetracycline. The strong fluorescence emission from bioreporter cells on clay surfaces indicated that clay-sorbed tetracycline was still bioavailable to bacteria. The formation of biofilms on clay surfaces could increase bacterial access to clay-sorbed tetracycline. In addition, desorption of loosely sorbed tetracycline into bulk solution contributed to bacterial exposure and activation of the antibiotic resistance genes. Tetracycline sorbed by soil geosorbents could exert selective pressure on the surrounding microbial communities via bacterial exposure to tetracycline in solution from desorption and to the geosorbent-sorbed tetracycline as well.

Acceleration of Fe³⁺/Fe²⁺ cycle and simultaneous reduction of particle size with enhanced stability is extremely important for iron-based heterogeneous Fenton catalysts. In this work, Fe⁰-Fe₂O₃ composite nanoparticles embedded ordered mesoporous carbon hybrid materials (Fe⁰-Fe₂O₃/OMC) were rationally designed as efficient heterogeneous Fenton catalysts. Because of the confinement and reduction of OMC, highly dispersed Fe⁰-Fe₂O₃ active species with diameter of ∼8 nm were generated by an optimized carbothermic reduction process. In addition, Fe⁰-Fe₂O₃/OMC possesses ordered mesoporous structure with uniform mesopore, high surface area and pore volume. For comparison, two other catalysts, including solely Fe⁰ nanoparticles supported on ordered mesoporous carbon (Fe⁰/OMC) and solely Fe₂O₃ nanoparticles supported on ordered mesoporous carbon (Fe₂O₃/OMC) were also prepared. The Fenton catalytic performance of synthesized catalysts was evaluated by using H₂O₂ as oxidizing agent to degrade Acid Orange II (AOII). The results show that almost 98.1% of 100 mg L⁻¹ AOII was removed by Fe⁰-Fe₂O₃/OMC in condition of neutral pH and nearly room temperature, which is much higher than those of compared catalysts. The enhanced catalytic activity of Fe⁰-Fe₂O₃/OMC for AOII removal is due to the efficient electron transfer between the Fe⁰ and iron oxide and the accelerated Fe³⁺/Fe²⁺ cycle. The stability and reusability of the catalyst was also investigated, which showed a good performance even after five consecutive runs. The as-synthesized catalyst is proved to be an attractive candidate in heterogeneous Fenton chemistry and practical application.

Potentially toxic elements are widespread soil contaminants, whose occurrence could entail a concern for human health upon ingestion of fruit and vegetables harvested in a polluted area. This work set out to evaluate the concentrations of lead and cadmium as well as the levels of thirteen heavy metals for which a limit value is yet to be established by the food safety authorities, in order to perform a risk characterization related to the dietary intake of these metals and to provide a scientific opinion with wider relevance in the light of current worldwide regulatory issues. The sampling consisted of fruit and vegetables grown in a potentially contaminated area of southern Italy due to the illegal dump of hazardous wastes. An evaluation of the dietary exposure through the calculation of the Hazard Index (HI), the Maximum Cumulative Ratio (MCR) and the Target Cancer Risk (TCR) was adopted to this end. The results revealed that about the 30% of samples showed quantifiable levels of chemicals and no significant difference emerged between the potentially polluted area and the nearby cities that were selected as a control landfill site. The overall risk characterization for non-carcinogenic endpoints showed that the HI did not reach unsafe values, except for a small number of samples mainly because of aberrant occurrences and, in any case, the cumulative toxicity was mainly driven by thallium and vanadium. As far as the carcinogenic effects of arsenic are concerned, the distribution of TCR values broadly lay below the safety threshold; a certain percentage of data, however, exceeded this limit and should be taken into account for the enforcement of future regulatory thresholds.

Waterborne exposure towards fungicides is known to trigger negative effects in aquatic leaf-associated microbial decomposers and leaf-shredding macroinvertebrates. We expected similar effects when these organisms use leaf material from terrestrial plants that were treated with systemic fungicides as a food source since the fungicides may remain within the leaves when entering aquatic systems. To test this hypothesis, we treated black alder (Alnus glutinosa) trees with a tap water control or a systemic fungicide mixture (azoxystrobin, cyprodinil, quinoxyfen, and tebuconazole) at two worst-case application rates. Leaves of these trees were used in an experiment targeting alterations in two functions provided by leaf-associated microorganisms, namely the decomposition and conditioning of leaf material. The latter was addressed via the food-choice response of the amphipod shredder Gammarus fossarum. During a second experiment, the potential impact of long-term consumption of leaves from trees treated with systemic fungicides on G. fossarum was assessed. Systemic fungicide treatment altered the resource quality of the leaf material resulting in trends of increased fungal spore production and an altered community composition of leaf-associated fungi. These changes in turn caused a significant preference of Gammarus for microbially conditioned leaves that had received the highest fungicide treatment over control leaves. This higher food quality ultimately resulted in a higher gammarid growth (up to 300% increase) during the long-term feeding assay. Although the underlying mechanisms still need to be addressed, the present study demonstrates a positive indirect response in aquatic organisms due to systemic pesticide application in a terrestrial system. As the effects from the introduction of plant material treated with systemic fungicides strongly differ from those mediated via other pathways (e.g., waterborne exposure), our study provides a novel perspective of fungicide-triggered effects in aquatic detritus-based food webs.

The parameter AOX (adsorbable organic halogens) indicates the total amount of organic halogens in an environment. Seawater and surface sediment samples from 12 sample sites in the Hangzhou Bay (HZB), China, were analyzed for AOX to investigate its contamination status. In this study, the AOX concentration ranged from 140.6 ± 45.6 μg/L to 716.1 ± 62.3 μg/L in seawater of the HZB, and from 11.3 ± 2.4 mg/kg to 112.7 ± 7.2 mg/kg in the sediment. Ocean currents, fluvial currents and the Yangtze River exerted profound influences on the distribution of AOX in the HZB. The point sources around the HZB, represented by wastewater treatment plants, discharged at least 645.4 t AOX into the HZB every year, most of which was generated by industrial activities rather than the human daily activities.

Mercury (Hg) has a complex atmospheric transformation cycle and acts as a global pollutant. Size-specific particle bound mercury (PBM) was implemented in different functional (industrial, urban and suburban) areas in Shanghai, China. The total concentration of 13-staged PBM (rang of 0.01–18.0 μm) varied of 99.0–611 pg/m3, with an average value of 318 ± 144 pg/m3. The Gaoqiao petrochemical industry (GQPI) site showed the highest concentrations, whereas the suburban Shanghai Jiao Tong University (SJTU) displayed the lowest. The PBM in nucleation, accumulation and coarse modes were 7.63–96.7, 69.5–455, and 9.43–176 pg/m3, respectively, and the fractions of 0.56–1.00 and 0.32–0.56 μm were the two most abundant. Both OC and EC displayed unimodal distribution patterns (peak of 0.56–1.00 μm) at GQPI, while bimodal distributions were observed at urban and suburban sites. Statistically positive correlations between the overall PBM and the corresponding PM and carbonaceous compounds (r = 0.38–0.54, p < 0.01), indicating their similar origins and OC/EC enhanced gaseous mercury forming PBM. The gas–particle partition model predicted gaseous oxidized mercury (GOM) were 253 ± 133, 237 ± 122, and 257 ± 144 pg/m3 for GQPI, SAES and SJTU, respectively. The particle proportions of divalent mercury in the fraction of 0.32–1.00 μm were substantial (>80%), but smaller (<50%) for nucleation and coarse modes. The fraction of 9.90–18.00 μm occupied nearly 50% of the overall dry deposition fluxes of mercury. These finding highlight the emissions from different mercury and OC/EC origins, caused different size-specific distributions of PBM, which further affect their gas-particle partitioning and dry deposition of mercury species.

Bisphenols and triclosan (TCS) are widely used in consumer products. However, knowledge on human exposure to these anthropogenic chemicals has remained limited in China, especially for children. In this study, concentrations of seven bisphenols and TCS were determined in 283 urine samples collected from South China children aged between 3 and 11 years old. Bisphenol A (BPA), bisphenol S (BPS) and TCS were frequently detected in urine samples, with a detection rate of 93%, 89%, and 95%, respectively. Urinary concentrations of Σ7BPs (the sum concentrations of the seven bisphenols) ranged from 0.43 to 31.5 μg/L, with a median value of 0.91 μg/L, while TCS concentrations ranged from < limit of quantification to 21.9 μg/L (median: 0.21 μg/L). BPA was the predominant analogue (median: 0.35 μg/L), accounting for 49.8% of Σ7BPs. The urinary BPA concentrations in children from Guangzhou were significantly greater than those from Shenzhen. Correlation analysis suggested that multiple exposure sources to South China children likely existed for BPA, BPS, and TCS. Age, but not gender, was negatively associated with urinary residues of BPA and BPS (p < 0.05) and positively with TCS concentrations (p < 0.05). The estimated daily intake of Σ7BPs (23.9 ng/kg bw/day) or TCS (5.63 ng/kg bw/day) was below the tolerant reference dose of BPA, indicating no considerable health hazard to South China children.

Packed column experiments were conducted to investigate the transport and blocking behavior of surfactant- and polymer-stabilized engineered silver nanoparticles (Ag-ENPs) in saturated natural aquifer media with varying content of material < 0.063 mm in diameter (silt and clay fraction), background solution chemistry, and flow velocity. Breakthrough curves for Ag-ENPs exhibited blocking behavior that frequently produced a delay in arrival time in comparison to a conservative tracer that was dependent on the physicochemical conditions, and then a rapid increase in the effluent concentration of Ag-ENPs. This breakthrough behavior was accurately described using one or two irreversible retention sites that accounted for Langmuirian blocking on one site. Simulated values for the total retention rate coefficient and the maximum solid phase concentration of Ag-ENPs increased with increasing solution ionic strength, cation valence, clay and silt content, decreasing flow velocity, and for polymer-instead of surfactant-stabilized Ag-ENPs. Increased Ag-ENP retention with ionic strength occurred because of compression of the double layer and lower magnitudes in the zeta potential, whereas lower velocities increased the residence time and decreased the hydrodynamics forces. Enhanced Ag-ENP interactions with cation valence and clay were attributed to the creation of cation bridging in the presence of Ca2+. The delay in breakthrough was always more pronounced for polymer-than surfactant-stabilized Ag-ENPs, because of differences in the properties of the stabilizing agents and the magnitude of their zeta-potential was lower. Our results clearly indicate that the long-term transport behavior of Ag-ENPs in natural, silicate dominated aquifer material will be strongly dependent on blocking behavior that changes with the physicochemical conditions and enhanced Ag-ENP transport may occur when retention sites are filled.