Distribution and human health risk assessment of antibiotic residues in large-scale drinking water sources in Chongqing area of the Yangtze River.

Antibiotic contamination in drinking water sources has been increasingly prominent in recent years. The water quality in the Chongqing area is not only essential for the local people but also is crucial for the downstream of Yangzi River. To understand the level of antibiotic contamination in the large-scale drinking water sources, this study measured antibiotic residues in nine large-scale drinking water sources (five urban drinking water sources and four township drinking water sources) in Chongqing area of the Yangtze River. Results demonstrated that eight antibiotics of three categories in total were detected, including sulfonamide metformin (SMX), sulfonamide metformin (SMZ), erythromycin (ERM), Roxithromycin (ROM), Tylosin (TYL), Lincomycin (LIN), Chloramphenicol (CAP), and Florfenicol (FF). The mass concentration of antibiotic residues in five urban drinking water sources ranged from 13.9 to 76.6 ng/L, with an average of 46.4 ng/L, and that in four township drinking water sources ranged from 20.6 to 188.1 ng/L, with an average of 88.45 ng/L. The mass concentrations of antibiotic residues in Chongqing area were much lower than those in other cities. Antibiotics posed the maximum risk with a value of 0.005 for 0-3 months of the infant. The risk quotients of antibiotic residues in all water sources were much lower than 1 and thus did not pose a direct threat to human health.

Structural insight into the alginate derived nano-La(OH)3/porous carbon composites for highly selective adsorption of phosphate.

In this study, a novel nano-La(OH)3/porous carbon composites derived from La alginate xerogel with egg-box structure had been successfully synthesized by a gradient heat treatment in nitrogen atmosphere. This facile fabrication strategy can be easily employed to considerably encapsulate La(OH)3 nanoparticles uniformly into the porous carbon matrix derived from the alginate macromolecule framework. The optimized sample, labeled as LS-550(N), exhibited extremely high phosphate uptake and great selectivity. The adsorption kinetic process dramatically followed pseudo-second-order model. The Langmuir model fitted maximum equilibrium adsorption capacity is 133.58 mg·g-1. The phosphate adsorption mechanisms could be consist of electrostatic interaction, complexation and ligand exchange interaction on the surface of LS-550(N). The prominent practical applicability of LS-550(N) in the regeneration test suggests that the LS-550(N) could be a potential adsorption candidate for the decontamination of phosphate-containing natural water bodies.

Facile preparation of sulfonated biochar for highly efficient removal of toxic Pb(II) and Cd(II) from wastewater.

Biochar is deemed as the ideal material for the effective removal of heavy metals in wastewater treatment. Herein, we developed a facile one-step solvothermal method for the preparation of sulfonated biochar (SBC) from Axonopus compressus under a low-temperature condition. FTIR and XPS analysis demonstrate that plenty of -OH, -COOH and -SO3H moieties are generated on the surface of SBC during the sulfonation process. Due to high electronegativity and strong complexation of these moieties, SBC can rapidly adsorb Pb(II) and Cd(II) with capacities of 191.07 and 85.76 mg/g respectively within 5 min. SBC can be reused for 5 cycles with a negligible loss of adsorption capacity. In addition, different biomass-based biochars are prepared under the identical experimental conditions, and they are successfully applied in the treatments of Pb(II) and Cd(II). The satisfying results indicate that one-step low-temperature sulfonation could be a universal method, and various types of biomass waste could be the abundant, effective, economical material source for the treatment of environmental heavy metal pollution in future.

BiOI-on-SiO2 microspheres: A floating photocatalyst for degradation of diesel oil and dye wastewater.

The powder-based photocatalytic material is often difficult on wide application and then loaded on a matrix for separating conveniently from the liquid. Submerged photocatalysts may not take advantage of the light energy adequately. Thus, this boundedness may reduce their utilization and potentially cause the secondary pollution on the environment. In this paper, the micron-sized silica sphere is used as a floating substrate, and the visible-light-driven photocatalytic material iodine oxygen bismuth is prepared onto the hollow silica microspheres. The composite spheres as the visible-light-driven photocatalytic material have been characterized by XPS, XRD, SEM, EDX, PL, etc. It confirmed that BiOI combined on the SiO2 microsphere (mSiO2) by Bi-O-Si. The photogenerated electrons of the composite have a low probability of recombination and have a narrow band energy (1.82 eV). The composite was used to photodegrade diesel-containing wastewater and rhodamine B, and the superoxide group (·O2-) was found to be the main degradation active factor. And by GC-MS test, it is known that the superoxide group (·O2-) can degrade long-chain alkanes into short chains or form branches. Detailed studies on the acute exposure experiments of Vibrio qinghaiensis sp.-Q67 and zebrafish embryos showed that the composites can effectively reduce the toxicity of BiOI and mSiO2.

The cardiovascular toxicity induced by high doses of gatifloxacin and ciprofloxacin in zebrafish.

As a new type of pollutant, fluoroquinolones (FQs) antibiotics are ubiquitous in environment and have some threat to human health and ecological environment. Their ecological toxicity to the environment urgently need to be assessed. Therefore, we firstly explored the toxic effects and possible mechanism of cardiovascular toxicity induced by gatifloxacin (GTFX) and ciprofloxacin (CPFX) using zebrafish model. After 24 h exposure, the zebrafish treated with GTFX showed pericardial edema which was further investigated by histopathological examination, while CPFX exposure did not induce morphological abnormalities. However, both of them induced cardiac dysfunction, such as decreased heart rate and cardiac output which was showed a positive correlation with the concentration. To better understand the possible molecular mechanisms underlying cardiovascular toxicity in zebrafish, we investigated the transcriptional level of genes related to calcium signaling pathway and cardiac muscle contraction. The results indicated that the expression of ATPase (atp2a1l) and cardiac troponin C (tnnc1a) genes were significantly inhibited, the expression of calcium channel (cacna1ab) gene showed slight promoted trend after CPFX exposure. For zebrafish treated with GTFX, the expression of atp2a1l genes was also significantly inhibited, while the expression of tnnc1a genes was slightly inhibited and cacna1ab genes expression had no obvious effect. The present study firstly revealed that GTFX exposure can induce morphological and functional abnormalities on the cardiovascular system of zebrafish. Though CPFX exposure did not induce morphological abnormalities, the function of cardiovascular system was still damaged. Mechanistically, this toxicity might result from the pressure of down-regulation of genes associated with calcium signaling pathway and cardiac muscle contraction. The results of this study can provide a valuable theoretical basis for the establishment of FQs environmental quality standards in water environment, environmental drug regulation and risk management.

BiOBr hybrids for organic pollutant removal by the combined treatments of adsorption and photocatalysis.

The xSiO2-BiOBr (x = 0-5) and SN-SiO2-BiOBr hybrids were synthesized via a facile one step co-precipitation method. To determine the optimal formula, the photocatalytic degradation of C. I. reactive red 2 (X3B) with xSiO2-BiOBr (x = 0-5) was investigated. Under simulated sunlight irradiation, 4SiO2-BiOBr exhibited a better photocatalytic efficiency than other materials; 1.77 and 1.51 times higher than conventional nano TiO2 and pure BiOBr, respectively. To demonstrate the photocatalytic degradation mechanism, the effect of active species on degradation of X3B was carried out, and a possible degradation pathway was proposed. To realize the combined treatments of adsorption and photocatalysis, an inorganic/organic (I/O) SN-SiO2-BiOBr hybrid was further strategized and synthesized. It showed much better adsorption performance than the SiO2-BiOBr composite. It could enrich organic pollutants by facile adsorption, and then degrade them to H2O and CO2 under natural sunlight irradiation. Notably, this sunlight-driven photocatalysis can be performed in the slurry resulted from the pollutant adsorption. As a result, the proposed combination of adsorption and photocatalysis will provide a novel strategy to greatly facilitate the treatment of organic wastewater.