A large eddy simulation (LES) model coupled with O3-NOx-VOC chemistry is implemented to simulate the coupled effects of emissions, mixing and chemical pre-processing within an idealised deep (aspect ratio = 2) urban street canyon under a weak wind condition. Reactive pollutants exhibit significant spatial variations in the presence of two vertically aligned unsteady vortices formed in the canyon. Comparison of the LES results from two chemical schemes (simple NOx-O3 chemistry and a more comprehensive Reduced Chemical Scheme (RCS) chemical mechanism) shows that the concentrations of NO2 and Ox inside the street canyon are enhanced by approximately 30–40% via OH/HO2 chemistry. NO, NOx, O3, OH and HO2 are chemically consumed, while NO2 and Ox (total oxidant) are chemically produced within the canyon environment. Within-canyon pre-processing increases oxidant fluxes from the canyon to the overlying boundary layer, and this effect is greater for deeper street canyons (as found in many traditional European urban centres) than shallower (lower aspect ratio) streets. There is clear evidence of distinct behaviours for emitted chemical species and entrained chemical species, and positive (or negative) values of intensities of segregations are found between pairs of species with similar (or opposite) behaviour. The simplified two-box model underestimated NO and O3 levels, but overestimated NO2 levels for both the lower and upper canyon compared with the more realistic LES-chemistry model. This suggests that the segregation effect due to incomplete mixing reduces the chemical conversion rate of NO to NO2. This study reveals the impacts of nonlinear O3-NOx-VOC photochemical processes in the incomplete mixing environment and provides a better understanding of the pre-processing of emissions within canyons, prior to their release to the urban boundary layer, through the coupling of street canyon dynamics and chemistry.

High nitrogen (N) inputs in Chinese vegetable and cereal productions played key roles in increasing crop yields. However, emissions of the potent greenhouse gas nitrous oxide (N2O) and atmospheric pollutant nitric oxide (NO) increased too. For lowering the environmental costs of crop production, it is essential to optimize N strategies to maintain high crop productivity, while reducing the associated N losses. We performed a 2 year-round field study regarding the effect of different combinations of poultry manure and chemical N fertilizers on crop yields, N use efficiency (NUE) and N2O and NO fluxes from a Welsh onion-winter wheat system in the North China Plain. Annual N2O and NO emissions averaged 1.14–3.82 kg N ha⁻¹ yr⁻¹ (or 5.54–13.06 g N kg⁻¹ N uptake) and 0.57–1.87 kg N ha⁻¹ yr⁻¹ (or 2.78–6.38 g N kg⁻¹ N uptake) over all treatments, respectively. Both N2O and NO emissions increased linearly with increasing total N inputs, and the mean annual direct emission factors (EFd) were 0.39% for N2O and 0.19% for NO. Interestingly, the EFd for chemical N fertilizers (N2O: 0.42–0.48%; NO: 0.07–0.11%) was significantly lower than for manure N (N2O: 1.35%; NO: 0.76%). Besides, a negative power relationship between yield-scaled N2O, NO or N2O + NO emissions and NUE was observed, suggesting that improving NUE in crop production is crucial for increasing crop yields while decreasing nitrogenous gas release. Compared to the current farmers’ fertilization rate, alternative practices with reduced chemical N fertilizers increased NUE and decreased annual N2O + NO emissions substantially, while crop yields remained unaffected. As a result, annual yield-scaled N2O + NO emissions were reduced by > 20%. Our study shows that a reduction of current application rates of chemical N fertilizers by 30–50% does not affect crop productivity, while at the same time N2O and NO emissions would be reduced significantly.

Environmental pollution by organic pollutants (OPs) has become a global concern due to its detrimental effects on the environment and human health. As plants are used to remediate contaminated sites, understanding the responses of plants to various OPs and fortification of plant tolerance are of great significance. In this work, we studied the biochemical and molecular responses of cucumber plants to three well-known OPs, 2,4,6-trichlorophenol, chlorpyrifos and oxytetracycline in the absence or presence of 24-epibrassinolide (EBR), a potent regulator of plant growth and stress tolerance. The results showed that the selected three OPs retarded root elongation; however, the phytotoxic effects of OPs were attenuated by exogenous EBR. OPs induced accumulations of both hydrogen peroxide (H2O2) and nitric oxide (NO) in root tips and resulted in an increased malondialdehyde (MDA) content, an indicator of membrane lipid peroxidation. Exogenous EBR reduced accumulations of H2O2, NO and MDA in the roots by increasing the expression of antioxidant and detoxification genes and the activities of the corresponding enzymes. Intriguingly, EBR not only promoted the activities of glutathione S-transferase and glutathione reductase, but also increased the content of reduced glutathione without altering the content of oxidized glutathione, which resulted in a reduced redox state under OPs stress. Furthermore, EBR increased the free radical scavenging capacity, flavonoid content and the activity and transcription of secondary metabolism related enzymes. Our results suggest that EBR treatment may fortify secondary metabolism to enhance antioxidant capacity in response to OPs treatment, which might have potential implication in phytoremediation of OPs.

This study investigated the effects of particle-bound polycyclic aromatic hydrocarbons (PAHs) produced from burning three incense types on and their bioreactivity in the RAW 264.7 murine macrophage cell line. Gas chromatography/mass spectrometry was used to determine the levels of 16 identified PAHs. Macrophages were exposed to incense particle extracts at concentrations of 0, 3.125, 6.25, 12.5, 25, 50, and 100 μg/mL for 24 h. After exposure, cell viability and nitric oxide (NO) and inflammatory mediator [tumor necrosis factor (TNF)-α] production of the cells were examined. The mean atomic hydrogen (H) to carbon (C) ratios in the environmentally friendly, binchotan charcoal, and lao shan incenses were 0.69, 1.13, and 1.71, respectively. PAH and total toxic equivalent (TEQ) mass fraction in the incenses ranged from 137.84 to 231.00 and 6.73–26.30 pg/μg, respectively. The exposure of RAW 264.7 macrophages to incense particles significantly increased TNF-α and NO production and reduced cell viability. The cells treated with particles collected from smoldering the environmentally friendly incense produced more NO and TNF-α compared to other incenses. Additionally, the TEQ of fluoranthene (FL), pyrene (Pyr), benzo[a]anthracene (BaA), chrysene (Chr), benzo[b]fluoranthene (BbF), benzo[k]fluoranthene (BkF), benzo[a]pyrene (BaP), indeno[1,2,3-cd]pyrene (INP), dibenz[a,h]anthracene (DBA), and benzo[g,h,i]perylene [B(ghi)P] had a significant correlation (R2 = 0.64–0.98, P < 0.05) with NO and TNF-α production. The current findings indicate that incense particle-bound PAHs are biologically active and that burning an incense with a lower H/C ratio caused higher bioreactivity. The stimulatory effect of PAH-containing particles on molecular mechanisms of inflammation are critical for future study.

The chemical composition of PM2.5 and cellular effects from exposure to fine aerosol extracts were studied for samples collected in Beijing, Tianjin, Shijiazhuang, and Hengshui, China in winter 2015. Effects of priority polycyclic aromatic hydrocarbons (PAHs) and their oxygenated derivatives (OPAHs) in PM2.5 on cell cultures were a major focus of the study. Total quantified PAHs and OPAHs at Shijiazhuang and Hengshui were higher than at Beijing and Tianjin, and benz(a)anthracene, chrysene and 1,8-naphthalic anhydride were the most abundant species. Exposure to PM2.5 extracts caused a concentration-dependent decline in cell viability and a dose-dependent increase in nitric oxide production. Two cytokines, tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6), also increased when A549 test cells were exposed to PM2.5 extracts. PAHs and OPAHs in PM2.5 can potentially cause cell damage and induce cytotoxicity and pro-inflammatory responses: benzo(a)anthracene-7,12-dione was highly correlated with NO production, dibenz(a,h)anthracene and 1,4-chrysenequinone were correlated with TNF-α production, and 1-naphthaldehyde was significantly correlated with IL-6 production. The study provides a new approach for evaluating relationships between air-quality and cell toxicity with respect to specific chemicals.

This study was to evaluate the influence of vehicular emissions on two islands located in the Guanabara Bay, Metropolitan Area of Rio de Janeiro city, one of them without the presence of vehicles (Paquetá Island - PI) and another with a considerable fleet (Governador Island - GI). The data used correspond to the hourly averages of the years 2012 and 2013 for nitrogen oxides (NOx, NO2 and NO), ozone (O3), carbon monoxide (CO), total hydrocarbons (THC), aromatic hydrocarbons (BTEX), as well as meteorological data. To interpret the results, a multivariate statistic was used in order to characterize the impact of the vehicle fleet on air quality. The results showed that CO and NOx levels were 2–6 times higher in GI than PI. On the other hand, THC levels were similar at both sites. Surprisingly, O3 levels were up to 1.5 times greater in PI than in GI. The possible explanation for these higher levels is related to the formation process from THC and NOx in the presence of sunlight. The THC/NOx and NOx/NO ratios for PI are much higher than those found for GI, thus explaining the high ozone values for a location with virtually no vehicle fleet and industrial activities. The benzene, toluene and xylene levels at both sites were of the same magnitude order, however, ethyl benzene was about 7-fold higher in PI.

Ascidians are good monitors for assessing water quality, since they filter large volumes of water; however, little is known about how xenobiotics, including metals, can affect ascidian hemocytes. Metals can be either toxic or beneficial to health, inducing many different responses. The response mechanism depends on the class of metals to which organisms are exposed: essential, nonessential, and borderline. To analyze the influence of metals from different classes on the protective mechanisms of an ascidian, we investigated the production of nitric oxide (NO) after exposure to various concentrations of Mg, Mn and Pb over different time periods. We also determined the amounts of each metal in the hemocytes. Our results indicated that especially Pb could stimulate NO production. Although Pb induced the highest NO production, cell viability was not severely altered in all Pb concentrations and time periods. Ascidians might serve as biomonitor for Pb, since their vanadocytes accumulate Pb.

Mussels (Mytilus spp.) are worldwide utilized in marine biomonitoring by a multi-biomarker approach. However, for a correct interpretation of different biomarker responses, information is needed on their natural seasonal variability due to environmental/physiological factors.In this work, the seasonal variations of different biomarkers were investigated in M. galloprovincialis from 4 different sites from the gulf of La Spezia (Ligurian sea, Italy), an intensive rearing area in the north-western Mediterranean near La Spezia harbor, an important commercial and touristic port. Lysosomal membrane stability-LMS, stress on stress-SoS, phagocytosis, tissue metallothionein-MT content, oxidative stress related enzyme activities (GST, catalase), and nitric oxide (NO) production were evaluated. The results underline the importance of LMS and SoS as core descriptors of the mussel health status in relation to seasonal variations in temperature and reproduction. These data represent the baseline information for ongoing biomonitoring studies related to dredging activities in this area.

In this study, the long-term trend in atmospheric carbon monoxide (CO) concentration was analyzed using the CO levels measured (intermittently) at an air quality monitoring (AQM) station in Seoul, Korea, between the years 1987 and 2013. Temporal trends in CO were analyzed on an annual and seasonal basis in reference to other important air pollutants such as methane (CH4), particulate matter (PM10), sulfur dioxide (SO2), nitrogen monoxide (NO), nitrogen dioxide (NO2), mercury (Hg), and ozone (O3). The annual mean of CO for the entire period was 0.93 ± 0.22 ppm. CO levels were reduced by 83% from 3.25 ± 0.78 ppm (1987) to 0.51 ± 0.31 ppm (2013). Its relative reduction was compared over three periods chosen arbitrarily as period 1 (fast reduction, 1987–1988), period 2 (intermediate reduction, 1999–2000), and period 3 (slow reduction, 2004–2013). The concentrations of CO were strongly correlated with others (e.g., SO2, NO, NO2, O3, and Hg), suggesting the effects of similar source processes (e.g., fuel combustion). The reduction in its level was marginally consistent with the decreasing trend in the total CO column concentration in Seoul by the Measurements of Pollution in the Troposphere (MOPITT) satellite between 2000 and 2013, indicating decreasing anthropogenic CO emissions (despite increasing anthropogenic CO2 emissions). The rapid relative reduction of CO in period 1 and the subsequent slower but moderate reduction thereafter appear to reflect the effects of both enforcement of administrative regulations and advances in emissions control technologies.

Ozone (O3) concentration, along with the concentrations of 10 precursors (acetone, toluene, ethylbenzene, benzene, xylenes, styrene, cyclohexane, NO, NO2, and CO), were measured and characterized at 16 locations in Riyadh, the capital city of Saudi Arabia, for the period of May through August 2012. The results showed that concentrations of all O3 precursors were high in central and industrial areas, owing mainly to road traffic volume and industrial emissions. Except for benzene, all pollutants featured a skewed distribution, which indicates that they might occasionally be influenced by contiguous sources of air pollution and/or by emissions from heavy air polluters. The benzene distribution does not follow this behavior, possibly due to the shortage of substantial stationary benzene emitters. Also, the considerable difference between the median and the mean of both xylene and toluene distributions suggests local emission impacts in Riyadh. O3 concentrations averaged 34.59 ± 24.17 ppb and were a maximum of 277.47 ppb, occasionally violating the 1-h national standard (120 ppb) and frequently exceeding World Health Organization (WHO) and United States Environmental Protection Agency (EPA) standards.