Abstract:The concentrations of polycyclic aromatic hydrocarbons (PAHs) in the air of Chengdu, a southwest city of China, were determined from March 2015 to February 2016. Here, two diagnostic ratios (DR) were determined and a principal component analysis/multiple linear regression (PCA/MLR) analysis was performed to identify the sources of PAHs during the four seasons. The gaseous and particle phase samples were analyzed separately. The sampled air had a gas-to particle ratio of 4.21, and between 18.7% and 31.3% of the total detected PAHs were found in the particulate phase. The total concentration of all 16-PAHs combined (gas + particles) varied from 176.94 in summer to 458.95 ng·m −3 in winter, with a mean of 300.35 ± 176.6 ng·m −3 . In the gas phase, phenanthrene(Phe) was found at the highest concentrations in all four seasons, while benzo[b]fluoranthene(BbF) and (in winter) chrysene(Chr) were the highest in the particle phase. The DR of Fluroanthene (Flua)/(Flua + Pyrene (Pyr)) was higher in the gas phase than in the particle phase, while the Indeno[1,2,3-cd]pyrene(IcdP)/(IcdP + Benzo[ghi]perylene (BghiP)) ratio was more variable in the gas than that in the particle phase. The main sources for both phases were a mixture of liquid fossil fuel combustion and the burning of biomass and coal, with clear seasonal variation. Principal Component Analysis/Multiple Linear Regression (PCA/MLR) analysis identified the main PAH sources as coal burning (52%) with motor vehicle exhaust and coke (48%) in spring; coal (52%), coke (21%), and motor vehicle exhaust (27%) in summer; coal (47%), vehicle exhaust (34%), and coke (19%) in autumn; and coal (58%) and vehicle exhaust (42%) in winter.

In this study, ultrasonic radiation zero-valent iron is used to remove tetracycline hydrochloride in aqueous solution. Zero-valent iron was characterized by SEM and XRD. The mechanism of tetracycline hydrochloride removal process by zero-valent iron was proposed. The effects of initial pH, zerovalent iron dosage, ultrasonic power and tetracycline hydrochloride concentration on the removal of tetracycline hydrochloride in the US-ZVI system were studied in detail. The US-ZVI system produces strong reducing agent •H and new Fe 2+ , which can rapidly reduce tetracycline hydrochloride. The results show that with the US-ZVI system, a lower initial pH helps accelerate the removal of tetracycline hydrochloride. In addition, with the US-ZVI system, with the increase of initial zero-valent iron dosage can promote the degradation of tetracycline hydrochloride. However, compared with pH, the zerovalent iron dosage has less effect on the degradation of tetracycline hydrochloride. In addition, the ultrasonic wave improves the degradation of tetracycline hydrochloride by zero-valent iron. The higher the ultrasonic power, the better the removal effect of tetracycline hydrochloride. However, the initial tetracycline hydrochloride dosage has hardly affected on the degradation efficiency of tetracycline hydrochloride. And the improvement of degradation rate is mainly due to the synergy between US and ZVI. Then, the recycling experiments were carried out. Finally, according to liquid chromatographymass spectrometry results, the degradation pathway of tetracycline hydrochloride was proposed.

To study the removal performance of a constructed rapid infiltration (CRI) system and its microbial community characteristics, we took the demonstration project of a CRI system that has successfully operated for 15 years as an example, aiming to analyze the CRI system's removal performances for COD, NH 4 +-N, TN and TP. Meanwhile, high-throughput sequencing technology was used for the first time to study the microbial community diversity and structure in the CRI system. The results showed that the average removal efficiencies for COD and NH 4 +-N were 75.52% and 92.94%, and the average removal efficiencies for TN and TP were respectively 39.74% and 42.78%. High-throughput sequencing technology indicated that a variety of bacterial phyla were found in CRI's bacterial communities, including Bacteroidetes, Actinobacteria and Acidobacteria, among which Proteobacteria dominated. At the genus level, a spatial variation was illustrated for the diversity and structure of bacterial communities. The dominant genera on the surface layer (0 cm) of CRI were mainly Nocardioides, Sphingomonas, Bryobacter and other microorganisms that can degrade organic matter, and the dominant genera in the inside (30-120 cm) were mainly microorganisms that play an important role in removing nitrogen. This study provided a theoretical basis for the long-term operation of a CRI system.

Anaerobic ammonium oxidation (anammox) refers to the biological nitrogen removal process in which anaerobic ammonium oxidation bacteria (AnAOB) oxidize NH 4 + directly into N 2 with NO 2 as electron acceptor in anaerobic conditions [1-2]. This technology is very promising, featuring no need for aeration, no need for additional carbon resources, high nitrogen removal efficiency, low sludge yield and small floor area [3-4]. As reported, the cost

In this study, we investigated the effect of dietary methionine restriction (MR) on the antioxidant function and inflammatory responses in lipopolysaccharide (LPS)-challenged broilers reared at high stocking density. A total of 504 one-day-old male Arbor Acre broiler chickens were randomly divided into four treatments: 1) CON group, broilers fed a basal diet; 2) LPS group, LPS-challenged broilers fed a basal diet; 3) MR1 group, LPS-challenged broilers fed a methionine-restricted diet (0.3% methionine); and 4) MR2 group, LPS-challenged broilers fed a methionine-restricted diet (0.4% methionine). LPS-challenged broilers were intraperitoneally injected with 1 mg/kg body weight (BW) of LPS at 17, 19, and 21 days of age, whereas the CON group was injected with sterile saline. The results showed that: LPS significantly increased the liver histopathological score (p < 0.05); LPS significantly decreased the serum total antioxidant capacity (T-AOC), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) activity at 3 h after injection (p < 0.05); the LPS group had a higher content of Interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF)-α, but a lower content of IL-10 than the CON group in serum (p < 0.05). Compared with the LPS group, the MR1 diet increased catalase (CAT), SOD, and T-AOC, and the MR2 diet increased SOD and T-AOC at 3 h after injection in serum (p < 0.05). Only MR2 group displayed a significantly decreased liver histopathological score (p < 0.05) at 3 h, while MR1 and MR2 groups did so at 8 h. Both MR diets significantly decreased serum LPS, CORT, IL-1β, IL-6, and TNF-α contents, but increased IL-10 content (p < 0.05). Moreover, the MR1 group displayed significantly increased expression of nuclear factor erythroid 2-related factor 2 (Nrf2), CAT, and GSH-Px at 3 h; the MR2 group had a higher expression of Kelch-like ECH-associated protein 1 (Keap1), SOD, and GSH-Px at 8 h (p < 0.05). In summary, MR can improve antioxidant capacity, immunological stress, and liver health in LPS-challenged broilers. The MR1 and MR2 groups experienced similar effects on relieving stress; however, MR1 alleviated oxidative stress more rapidly. It is suggested that precise regulation of methionine levels in poultry with stress may improve the immunity of broilers, reduce feed production costs, and increase production efficiency in the poultry industry.