Decomposition of aquatic macrophytes usually generates significant influence on aquatic environment. Study on the aquatic macrophytes decomposition may help reusing the aquatic macrophytes litters, as well as controlling the water pollution caused by the decomposition process. This study verified that the decomposition processes of three different kinds of aquatic macrophytes (water hyacinth, hydrilla and cattail) could exert significant influences on water quality of the receiving water, including the change extent of pH, dissolved oxygen (DO), the contents of carbon, nitrogen and phosphorus, etc. The influence of decomposition on water quality and the concentrations of the released chemical materials both followed the order of water hyacinth > hydrilla > cattail. Greater influence was obtained with higher dosage of plant litter addition. The influence also varied with sediment addition. Moreover, nitrogen released from the decomposition of water hyacinth and hydrilla were mainly NH3-N and organic nitrogen while those from cattail litter included organic nitrogen and NO3⁻-N. After the decomposition, the average carbon to nitrogen ratio (C/N) in the receiving water was about 2.6 (water hyacinth), 5.3 (hydrilla) and 20.3 (cattail). Therefore, cattail litter might be a potential plant carbon source for denitrification in ecological system of a constructed wetland.

There are serious concerns over the adverse impacts of microplastics (MPs) on living organisms. The main objective of this study was to test the effects of MPs on the total length, weight, condition factor (CF), transcriptional level of antioxidant, anti and pro-apoptotic, and neurotransmitter genes, and the histopathology of the gill, liver, brain, kidney, and intestine in the larvae of zebrafish (Danio rerio). Fish were exposed to one of three levels of pristine low-density polyethylene (LDPE) fragments (5, 50, or 500 μg/L) for 10 or 20 days. No significant changes were observed in any of the selected biomarkers across MP concentrations at days 10 or 20. The expression of casp9 (caspase 9, apoptosis-related cysteine protease), casp3a (caspase 3, apoptosis-related cysteine protease a) and cat (catalase), however, were significantly lower in the larvae sampled at day 20 than day 10. We provide evidence that virgin short-term exposure to LDPE fragments has minimal impact on biomarker responses in D. rerio larvae.

This study investigates reaction pathways for the formation of pre-PXDD/F intermediates via a radical/molecule mechanism. Thermodynamic and kinetic parameters for the combination reactions of 2-bromophenol (2-BP) and 2-chlorophenol (2-CP) precursors with key radical species including the phenoxy radicals, the phenyl radicals and the phenoxyl diradicals were calculated in detail. The couplings of phenoxy radicals with 2-B(C)P tend to produce pre-PXDD intermediates of halogenated o-phenoxyphenol. The combinations of phenyl and phenoxyl diradicals with 2-B(C)P produce two types of structures, i.e., dihydroxybiphenyl and o-phenoxyphenyl, which exclusively act as prestructures of PXDFs. These condensation reactions, especially those involving the phenyl C atom sites in phenyl and phenoxyl diradicals, are proven to be both thermodynamically and kinetically favorable and are nearly comparable with the corresponding steps involved in the radical/radical reactions. Most importantly, reactions of phenyl and phenoxyl diradicals with halogenated phenols solely lead to the formation of PXDFs, which to some extent provides a plausible explanation for the high PXDF-to-PXDD ratios in the real environment. Therefore, our study reveals the pivotal role of the radical/molecule mechanism in homogeneous gas-phase PXDD/F formation, especially in PXDF formation. The present results fill in a knowledge gap that has hitherto existed regarding dioxin formation and improve our understanding of PXDD/F formation characteristics in the environment.

Air quality is closely related to quality of life. Air pollution forecasting plays a vital role in air pollution warnings and controlling. However, it is difficult to attain accurate forecasts for air pollution indexes because the original data are non-stationary and chaotic. The existing forecasting methods, such as multiple linear models, autoregressive integrated moving average (ARIMA) and support vector regression (SVR), cannot fully capture the information from series of pollution indexes. Therefore, new effective techniques need to be proposed to forecast air pollution indexes. The main purpose of this research is to develop effective forecasting models for regional air quality indexes (AQI) to address the problems above and enhance forecasting accuracy. Therefore, two hybrid models (EMD-SVR-Hybrid and EMD-IMFs-Hybrid) are proposed to forecast AQI data. The main steps of the EMD-SVR-Hybrid model are as follows: the data preprocessing technique EMD (empirical mode decomposition) is utilized to sift the original AQI data to obtain one group of smoother IMFs (intrinsic mode functions) and a noise series, where the IMFs contain the important information (level, fluctuations and others) from the original AQI series. LS-SVR is applied to forecast the sum of the IMFs, and then, S-ARIMA (seasonal ARIMA) is employed to forecast the residual sequence of LS-SVR. In addition, EMD-IMFs-Hybrid first separately forecasts the IMFs via statistical models and sums the forecasting results of the IMFs as EMD-IMFs. Then, S-ARIMA is employed to forecast the residuals of EMD-IMFs. To certify the proposed hybrid model, AQI data from June 2014 to August 2015 collected from Xingtai in China are utilized as a test case to investigate the empirical research. In terms of some of the forecasting assessment measures, the AQI forecasting results of Xingtai show that the two proposed hybrid models are superior to ARIMA, SVR, GRNN, EMD-GRNN, Wavelet-GRNN and Wavelet-SVR. Therefore, the proposed hybrid models can be used as effective and simple tools for air pollution forecasting and warning as well as for management.

This study examined effects of short-term urban air pollution exposures on inflammation, thrombosis, and autonomic imbalance in subjects at risk for cardiovascular disease (CVD). We enrolled 61 patients with multiple CVD risk factors and measured high sensitive C-reactive protein (hs-CRP), fibrinogen, D-dimer, and heart rate variability (HRV) indices. Two health examinations for each participant were performed during December 2002 through September 2003. Changes in inflammation and thrombotic markers and HRV indices with exposures to PM2.5, organic carbon (OC), elemental carbon (EC), sulfur dioxide (SO2), nitrogen dioxide (NO2), and carbon monoxide (CO) at 1- to 3-day lags were analyzed using mixed models. The results showed inflammatory and thrombotic markers increased with 1- to 3-day lagged PM2.5 components and gaseous pollutants exposures. hs-CRP maximally increased 0.19 [95% confidence interval (CI): 0.07–0.31] and 0.15 (95% CI: 0.05–0.24) mg/L for an interquartile range (IQR) of 1-day lagged SO2 (2.3 ppb) and CO (0.5 ppm), respectively. D-dimer maximally increased 1.05 (95% CI: 0.13–1.75), 0.72 (95% CI: 0.09–1.21), 0.92 (95% CI: 0.13–1.50), and 0.90 (95% CI: 0.07–1.61) mg/dL for an IQR of 1-day lagged OC (3.9 μg/m3), EC (2.0 μg/m3), SO2, and NO2 (13.4 ppb), respectively. The HRV indices, including low frequency, very low frequency, and the ratio of low frequency to high frequency decreased 19.8 (95% CI: 4.4–32.7), 12.9 (95% CI: 0.8–23.4), and 17.6 (95% CI: 5.4–28.2)% for an IQR of 1-day lagged PM2.5 (20.2 μg/m3), respectively. Our findings demonstrated PM2.5 components and gaseous pollutants exert prolonged inflammatory and thrombotic reactions, while PM2.5 exert an immediate autonomic imbalance.

In the last few years, ship emissions have attracted growing attention in the scientific community. The main reason is the constant increase of marine emissions over the last twenty years due to the intensification of port traffic. Thus, this study aimed to evaluate ship emissions (PM10, PM2.5, NOx, SO2, CO, CO2, N2O CH4, NMVOC, and HC) through the activity-based methodology in four of the main ports of Portugal (Leixões, Setúbal, Sines and Viana do Castelo) during 2013 and 2014. The analysis was performed according to ship types (bulk carrier, container, general cargo, passenger, Ro-Ro cargo, tanker and others) and operational modes (manoeuvring, hotelling and during cruising). Results indicated that tankers were the largest emitters in two of the four analysed ports. Regarding cruising emissions, container ships were the largest emitters. . CO2, NOx and SO2 estimated emissions represented more than 95% of the cruising and in-port emissions. Results were also compared with the total national emissions reported by the Portuguese Environment Agency, and if the in-port emissions estimated in the present study would have been taken into account to these totals, emissions of NOx and SO2 would increase 15% and 24% in 2013 and 16% and 28% in 2014. Summing up ships seem to be an important source of air pollution, mainly regarding NOx and SO2.

Benzotriazole ultraviolet stabilizers (BUVSs) are prominent chemicals widely used in industrial and consumer products to protect against ultraviolet radiation. They are becoming contaminants of emerging concern since their residues are frequently detected in multiple environmental matrices and their toxicological implications are increasingly reported. We herein investigated the antiandrogenic activities of eight BUVSs prior to and after human CYP3A4-mediated metabolic activation/deactivation by the two-hybrid recombinant human androgen receptor yeast bioassay and the in vitro metabolism assay. More potent antiandrogenic activity was observed for the metabolized UV-328 in comparison with UV-328 at 0.25 μM ((40.73 ± 4.90)% vs. (17.12 ± 3.00)%), showing a significant metabolic activation. In contrast, the metabolized UV-P at 0.25 μM resulted in a decreased antiandrogenic activity rate from (16.08 ± 0.95)% to (6.91 ± 2.64)%, indicating a metabolic deactivation. Three mono-hydroxylated (OH) and three di-OH metabolites of UV-328 were identified by ultra-performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-Q-TOF-MS/MS), which were not reported previously. We further surmised that the hydroxylation of UV-328 occurs mainly at the alicyclic hydrocarbon atoms based on the in silico prediction of the lowest activation energies of hydrogen abstraction from C-H bond. Our results for the first time relate antiandrogenic activity to human CYP3A4 enzyme-mediated hydroxylated metabolites of BUVSs. The biotransformation through hydroxylation should be fully considered during the health risk assessment of structurally similar analogs of BUVSs and other emerging contaminants.

Data on fine particulate matter (PM2.5) in China were first announced in 2013. The primary objective of this study was to evaluate the acute effects of PM2.5 on asthma morbidity in Beijing, China. A total of 978,658 asthma hospital visits consisting of 928,607 outpatient visits, 40,063 emergency room visits and 9988 hospital admissions from January 1, 2010, to June 30, 2012, were identified from the Beijing Medical Claim Data for Employees. A generalized additive Poisson model was applied to explore the association between PM2.5 and health service use. The mean daily PM2.5 concentration was 99.5 μg/m3 with a range from 7.2 μg/m3 to 492.8 μg/m3. Ambient PM2.5 concentration was significantly associated with increased use of asthma-related health services. Every 10 μg/m3 increase in PM2.5 concentration on the same day was significantly associated with a 0.67% (95% CI, 0.53%–0.81%), 0.65% (95% CI, 0.51%–0.80%), and 0.49% (95% CI, 0.35%–0.64%) increase in total hospital visits, outpatient visits and emergency room visits, respectively. The exposure–response association between PM2.5 concentration and hospital visits for asthma exacerbations was approximately linear. In conclusion, this study found that short-term elevations in PM2.5 concentration may increase the risk of asthma exacerbations. Our findings contribute to the limited scientific literature concerning the acute effects of PM2.5 on asthma morbidity outcomes in developing countries.

Disinfectant used in drinking water treatment and distribution system can induce culturable bacteria, including various kinds of pathogenic bacteria, into viable but non-culturable (VBNC) state. The loss of cultural state, resuscitation and environmental persistence of VBNC bacteria will severely damage drinking water microbiological safety and thus pose a risk to public health. The manner in which chlorination treatment induced a VBNC state in Escherichia coli and the antibiotic persistence of VBNC bacteria was investigated. It was found that low dosage of chlorine (0.5 mg L−1) disinfection effectively reduced the culturability of E. coli and induced a VBNC state, after which metabolic activity was reduced and persistence to 9 typical antibiotics was enhanced. Furthermore, RT-qPCR results showed that stress resistance genes (rpoS, marA, ygfA, relE) and ARGs, especially efflux genes were up-regulated compared with culturable cells. The intracellular concentration was tested and found to be lower in VBNC cells than in actively growing E. coli, which suggested a higher efflux rate. The data presented indicate that VBNC E. coli are more persistent than culturable counterparts to a wide variety of antibiotics. VBNC E. coli constitute a potential source of contamination and should be considered during monitoring of drinking water networks.

Mixed contamination of nitrate and antibiotics/antibiotic-resistant genes (ARGs) is an emerging environmental risk to farmland soil. This is the first study to explore the role of excessive anthropogenic nitrate input in the anoxic dissipation of soil antibiotic/ARGs. During the initial 10 days of incubation, the presence of soil antibiotics significantly inhibited NO3− dissipation, N2O production rate, and denitrifying genes (DNGs) abundance in soil (p < 0.05). Between days 10 and 30, by contrast, enhanced denitrification clearly prompted the decline in antibiotic contents and ARG abundance. Significantly negative correlations were detected between DNGs and ARGs, suggesting that the higher the DNG activity, the more dramatic is the denitrification and the greater are the antibiotic dissipation and ARG abundance. This study provides crucial knowledge for understanding the mutual interaction between soil DNGs and ARGs in the enhanced anoxic denitrification condition.