In this study, the phototoxicity of cadmium sulfide (CdS), molybdenum disulfide (MoS2), and tungsten disulfide (WS2) nanoparticles (NPs) toward Escherichia coli (E. coli) under UV irradiation (365 nm) was investigated. At the same mass concentration of NPs, the toxicity of three NPs decreased in the order of CdS > MoS2 > WS2. For example, the death rates of E. coli exposed to 50 mg/L CdS, MoS2, and WS2 were 96.7%, 38.5%, and 31.2%, respectively. Transmission electron microscope and laser scanning confocal microscope images of E. coli exposed to three NPs showed the damage of cell walls and release of intracellular components. The CdS-treated cell wall was more extensively damaged than those of MoS2-treated and WS2-treated bacteria. WS2 and MoS2 generated superoxide radical (O2⁻), singlet oxygen (¹O2), and hydroxyl radical under UV irradiation, CdS produced only O2⁻ and ¹O2. CdS and WS2 released ions under UV irradiation, while MoS2 did not. Reactive oxygen species (ROS) generation and toxic ion release jointly resulted in the antibacterial activities of CdS and WS2. ROS generation was the dominant toxic mechanism of MoS2 toward the bacteria. This study highlighted the importance of considering the hazardous effect of sulfide NPs after their release into natural waters under light irradiation condition.

In this research, adsorption of Cu(II) and Cd(II) by biochars was investigated. To enhance the adsorption of these two metal ions, a simple modification of biochars by phosphoric acid (H(3)PO(4)) was carried out. The surface area was larger and the contents of oxygen-containing functional groups of modified biochars were more than pristine biochars. In comparison with pristine biochar, modified biochars sorbed Cu(II) and Cd(II) much more strongly. Surface area had significant effects on the sorption of Cu(II) and Cd(II) by modified biochars. X-ray photoelectron spectroscopy analyses indicated that the quantities of carboxyl (-COOH) and hydroxyl (-OH) functional groups of modified biochars were larger than those of pristine biochar at the same pyrolysis temperature. Compared with that of pristine biochars, the strong ability of -COOH and -OH of modified biochars to form complexes with Cu(II)/Cd(II) ions resulted in higher adsorption of these two metal ions. The phosphorus-containing groups of modified biochars, such as P=O and P=OOH from the result of Fourier transform infrared spectroscopy, interacted and also formed complexes with metal ions, possibly resulting in the enhanced adsorption of Cu(II) and Cd(II). Thus, sorption of metal ions by modified biochars was controlled by the mechanism of surface complexation between oxygen containing functional groups and metals. In general, the H(3)PO(4) modification was an effective method that prepared biochars with a high affinity for the sorption of heavy metals.

This manuscript evaluates spatial and temporal variations of source contributions to ambient fine particulate matter (PM2.5) in Israeli, Jordanian, and Palestinian cities. Twenty-four hour integrated PM2.5 samples were collected every six days over a 1-year period (January to December 2007) in four cities in Israel (West Jerusalem, Eilat, Tel Aviv, and Haifa), four cities in Jordan (Amman, Aqaba, Rahma, and Zarka), and three cities in Palestine (Nablus, East Jerusalem, and Hebron). The PM2.5 samples were analyzed for major chemical components, including organic carbon and elemental carbon, ions, and metals, and the results were used in a positive matrix factorization (PMF) model to estimate source contributions to PM2.5 mass. Nine sources, including secondary sulfate, secondary nitrate, mobile, industrial lead sources, dust, construction dust, biomass burning, fuel oil combustion and sea salt, were identified across the sampling sites. Secondary sulfate was the dominant source, contributing 35% of the total PM2.5 mass, and it showed relatively homogeneous temporal trends of daily source contribution in the study area. Mobile sources were found to be the second greatest contributor to PM2.5 mass in the large metropolitan cities, such as Tel Aviv, Hebron, and West and East Jerusalem. Other sources (i.e. industrial lead sources, construction dust, and fuel oil combustion) were closely related to local emissions within individual cities. This study demonstrates how international cooperation can facilitate air pollution studies that address regional air pollution issues and the incremental differences across cities in a common airshed. It also provides a model to study air pollution in regions with limited air quality monitoring capacity that have persistent and emerging air quality problems, such as Africa, South Asia and Central America.

In the study, the capability of Paecilomyces lilacinus XLA (CCTCC: M2012135) to reduce Cr6+ and its main antagonistic mechanisms to Cr6+ were experimentally evaluated. Activated growing fungus XLA efficiently reduced over 90% Cr6+ in the media with Cr6+ concentration below 100 mg L−1 at pH 6 after 14 days. After 1-day exposure to 100 mg L−1 Cr6+, nearly 50% of Cr6+ was reduced. Moreover, SO42− stimulated Cr6+ reduction, whereas other interferential ions inhibited Cr6+ reduction. The interaction mechanisms between XLA and Cr6+ mainly involve biotransformation, biosorption, and bioaccumulation, as detected by electron microscopy and chemical methods. The lower concentrations of Cr6+ (5 and 50 mg L−1) stimulated the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) level in XLA, respectively, but the higher concentration of Cr6+ (150 mg L−1) decreased the enzymatic activities and GSH concentration. The results implied that SOD, CAT and GSH were defensive guards to the oxidant stress produced by Cr6+. All these extracellular/intracellular defense systems endowed XLA with the ability to resist and detoxify Cr6+ by transforming its valent species. The fungus XLA could efficiently reduce Cr6+ under different environmental conditions (pH, interferential ions, and concentration). Moreover, XLA could endure the high concentration of Cr6+ probably due to its high biotransformation capability of Cr6+ and intracellular antioxidant systems for the detoxification of ROS generated by external Cr6+. All these results suggested that the fungus XLA can be applied to remediation of Cr6+-contaminated environments.

Heze city, a medium-size city in Shandong province, Eastern China. Ambient PM2.5 samples were collected in urban area of Heze from August 2015 to April 2016, and chemical species and sources of PM2.5 were investigated in this paper. The results indicated that the average concentration of PM2.5 was 100.9 μg/m3 during the sampling period, and the water-soluble ions, carbonaceous species included elemental carbon (EC) and organic carbon (OC), as well as elements contributed 32.7–51.7%, 16.3% and 12.5%, respectively, to PM2.5. Pearson's correlation analysis showed that the existing form of NH4+ was more complex and diverse in spring/summer, and ammonium nitrate, ammonium sulfate and ammonium hydrogen sulfate might be major form of NH4+ in autumn/winter. Correlation analysis between PM2.5 and SO42−/NO3−, PM2.5 and OC/EC during different seasons suggested that mobile sources might make an important impact on the increase of PM2.5 concentrations in spring/summer, and stationary sources might play a critical role on the increase of PM2.5 concentrations in autumn/winter. Seven factors were selected in Positive Matrix Factorization (PMF) models analysis based on the Error Estimation (EE) diagnostics during different seasons. Secondary source had the highest contribution to PM2.5 in Heze for the whole year, and followed by coal combustion, vehicle exhaust, soil dust, construction dust, biomass burning and metal manufacturing, and their annual contributions to PM2.5 were 26.5%, 17.2%, 16.5%, 11.5%, 7.7%, 7.0% and 3.8%, respectively. The air masses that were originated from Mongolia reflected the features of large-scale and long-distance air transport; while the air masses that began in Jiangsu, Shandong and Henan showed the features of small-scale and short-distance. Shandong, Henan and Jiangsu were identified as the major potential sources-areas of PM2.5 by using potential source contribution function (PSCF) and concentration-weighted trajectory (CWT) models.

Measuring black carbon (BC) is critical to understand the impact of combustion aerosols on air quality and climate change. In this study, BC was measured in 2014 at a unique community formed with rapid economic development and urbanization in an urban-rural fringe area of Beijing. Hourly BC concentrations were 0.1–33.5 μg/m3 with the annual average of 4.4 ± 3.7 μg/m3. BC concentrations had clear diurnal, weekly, and seasonal variations, and were closely related with atmospheric visibility. The absorption coefficient of aerosols increased while its contribution to extinction coefficient decreased with the enhancement of PM2.5 concentration. The high mass absorption efficiency (MAE) of EC was attributed to a combination of coal combustion, vehicular emission and rapidly coating by water-soluble ions and organic carbon (OC). BC concentrations followed a typical lognormal pattern, with over 88% samples in 0.1–10.0 μg/m3. Low BC levels were mostly bounded up with winds from north and northwest. Coal combustion and biomass burning were closely associated with severe haze pollution events. Firework discharge had significant UV absorption contribution. During the Asia-Pacific Economic Cooperation (APEC) forum in November 2014, air quality obviously improved due to various control strategies.

The objective of this study was to investigate associations between cardiovascular effects and urban ambient particle constituents using an in vivo crossover experimental design. Ambient particles were introduced to an exposure chamber for whole-body exposure of WKY rats, where the particulate matter with an aerodynamic diameter of <2.5 μm (PM2.5) mass concentration, particle number concentration, and black carbon (BC) were monitored. Organic carbon (OC), elemental carbon (EC), and soluble ions of PM2.5 were determined. In a crossover design, rats were exposed to ambient particles or high-efficiency particle arrestance (HEPA)-filtered control air for 7 days following a 7-day washout interval. The crossover exposure between particles and HEPA-filtered air was repeated 4 times. Radiotelemetric data on blood pressure (BP) [systolic BP (SBP), diastolic BP (DBP), pulse pressure (PP), and mean arterial pressure (MAP)], heart rate (HR), and heart rate viability (HRV) were subsequently obtained during the entire study. Exposure to the PM2.5 mass concentration was associated with decreases in the SBP, DBP, MAP, and HR (p < 0.05), whereas no significant changes in the BP or HR occurred with the particle number or black carbon. For HRV, the ln 5-min standard deviation of the normal-to-normal (NN) interval (LnSDNN) and the ln root mean square of successive differences in adjacent NN intervals (LnRMSSD) were positively associated with the PM2.5 mass concentration (p < 0.05). There were no significant effects of the particle number concentration or BC on HRV. Alterations in the HR were associated with OC, EC, Na⁺, Cl⁻, and NO3⁻. Cl⁻ was associated with the DBP, MAP, HR, SDNN, and RMSSD. NO3⁻ was correlated with the SBP, MAP, HR, SDNN, and RMSSD. In conclusion, we observed cardiovascular responses to ambient particles in vivo using a crossover design which can reduce animal use in future environmental studies.

Many antibiotics, including sulfonamides, are being frequently detected in soil and groundwater. Livestock waste is an important source of antibiotic pollution, and sulfonamides may be present along with organic-rich substances. This study aims to investigate the sorption reaction of two sulfonamides, sulfamethoxazole (SMZ) and sulfapyridine (SPY) in two organic-rich sorbents: a commercial peat soil (38.41% carbon content) and a composted manure (24.33% carbon content). Batch reactions were conducted to evaluate the impacts of pH (4.5–9.5) and background ions (0.001 M–0.1 M CaCl2) on their sorption. Both linear partitioning and Freundlich sorption isotherms fit the reaction well. The n values of Freundlich isotherm were close to 1 in most conditions suggesting that the hydrophobic partition is the major adsorption mechanism. In terms of SMZ, Kd declined with increases in the pH. SPY has a pyridine group that is responsible for adsorption at high pH values, and thus, no significant trend between Kd and pH was observed. At high pH ranges, SPY sorption deviated significantly from linear partitioning. The results suggested the sorption mechanism of these two sulfonamide antibiotics tended to be hydrophobic partitioning under most of the experimental conditions, especially at pH values lower than their corresponding pKa2. The fluorescence excitation emission matrix and dissolved organic carbon leaching test suggested composted manure has higher fulvic acid organics and that peat soil has higher humus-like organics. Small organic molecules showed stronger affinity toward sulfonamide antibiotics and cause the composted manure to exhibit higher sorption capacity. Overall, this study suggests that the chemical structure and properties of sulfonamides antibiotics and the type of organic matter in soils will greatly influence the fate and transport of these contaminants into the environment.

Although leaded gasoline has been banned in some megacities in China since 1997 and nationally since 2000, atmospheric lead (Pb) pollution is still an important issue in China, as its concentration in megacities such as Beijing remains high. To measure the Pb concentration and identify sources of Pb-containing particles in Beijing during January 2013, both an online Single Particle Aerosol Mass Spectrometer (SPAMS) and offline filters analyzed by inductively coupled plasma-mass spectrometer (ICP-MS) were used at a monitoring site on the Peking University (PKU) campus. The average Pb concentration in PM2.5 was 370 ng/m3 in January 2013 and the highest daily concentration was as high as 1.3 μg/m³ during our sampling period. Based on the mass spectra from the SPAMS, these particles were classified into 4 major types, including NO3-rich (61%), ECOC-rich (18%), Fe-rich (14%), and SO4-rich (7%). Results from this study suggest that combustion processes and the iron/steel industry were the major primary sources of Pb in Beijing. On clean days, the importance of the primary combustion particle type (ECOC-rich) increased, while during severe haze episodes, Pb-containing particles mixed with secondary ions and Fe were dominant. Based on estimates from the CMAQ model, on average 45% of Pb in PM2.5 in urban Beijing was transported in January 2013, with a much higher percent transported during the haze episodes. The percentage of transported Pb increased with the concentration of Pb and PM2.5, indicating that emissions from the surrounding areas need to be controlled during high Pb episodes in Beijing in winter.

ZnO nanoparticles (ZnO-NPs) are emerging contaminants that raise the concerns of potential risk in the aquatic environment. It has been estimated that the environmental ZnO-NPs concentration is 76 μg/l in the aquatic environment. Our aim was to determine the aquatic toxicity of ZnO-NPs with chronic exposure at environmentally relevant concentrations using the nematode Caenorhabditis elegans. Two simulated environmentally relevant mediums—moderately hard reconstituted water (EPA water) and simulated soil pore water (SSPW)—were used to represent surface water and pore water in sediment, respectively. The results showed that the ZnO-NPs in EPA water has a much smaller hydrodynamic diameter than that in SSPW. Although the ionic release of Zn ions increased time-dependently in both mediums, the Zn ions concentrations in EPA water increased two-fold more than that in SSPW at 48 h and 72 h. The ZnO-NPs did not induce growth defects or decrease head thrashes in C. elegans in either media. However, chronic exposure to ZnO-NPs caused a significant reduction in C. elegans body bends in EPA water even with a relatively low concentration (0.05 μg/l); similar results were not observed in SSPW. Moreover, at the same concentrations (50 and 500 μg/l), body bends in C. elegans were reduced more severely in ZnO-NPs than in ZnCl2 in EPA water. The ATP levels were consistently and significantly decreased, and ROS was induced after ZnO-NPs exposure (50 and 500 μg/l) in EPA water. Our results provide evidences that chronic exposure to ZnO-NPs under environmentally relevant concentrations causes metabolic and locomotive toxicities implicating the potential ecotoxicity of ZnO-NPs at low concentrations in aquatic environments.