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University students are constantly exposed to potential bacterial pathogens and environmental pollutants in indoor environment because they spend most of their time indoors. University dormitory and printing shop are two typical indoor environments frequented by university students. However, little is known about the characteristics of bacterial community as well as the effect of indoor environmental factors on them. 16S rRNA gene sequencing was used to reveal the bacterial community in indoor dust, electronic devices were recorded during dust sampling, and polybrominated diphenyl ethers (PBDEs) were detected by gas chromatography mass spectrometry (GC-MS). Proteobacteria , Actinobacteria and Firmicutes were leading phyla, and Acinetobacter , Paracoccus and Kocuria were dominating genera. The predominant genera showed Acinetobacter > Paracoccus > unidentified Corynebacteriaceae in indoor dusts from university dormitories, whereas Paracoccus > unidentified Cyanobacteria > Acinetobacter in printing shops. The occurrence of Acinetobacter , Kocuria , Corynebacterium , Pseudomonas , and Bacillus suggested the health risks of potential pathogenic bacteria to university students. Significant differences of microbial composition and diversity were proved between university dormitories and printing shops. Chemoheterotrophy and aerobic chemoheterotrophy were dominant bacterial functions, and the seven primary bacterial functions displayed university dormitory > printing shop. BDE 138 and BDE 66 were main environmental parameters affecting the indoor dust bacterial community in university dormitory, while printer and BDE 47 played dominating role in shaping microorganism in printing shop. The complex biotic (potential bacterial pathogens) and abiotic factors (electronic equipment and chemical pollutants) in indoor dusts may pose potential health risks to university students. [Display omitted] • Acinetobacter, Kocuria, Corynebacterium, Pseudomonas, and Bacillus were potential pathogens. • Printer and BDE 47 were crucial factors shaping indoor bacterial community. • Potential pathogens and PBDEs may pose health risks to university students. [ABSTRACT FROM AUTHOR]

The effect of sediment and residual fish feed on aquaculture water bodies has gained increasing attention to alleviate the eutrophication and heavy metals enrichment induced by aquaculture. Thus, this study intended to reveal the possible interactions among nutrients, heavy metals, and Chlorella vulgaris (C. vulgaris) in aquaculture water bodies containing fish feed and sediment. The analyses showed that consistent with the composition of heavy metals in fish feed, manganese (Mn) and zinc (Zn) accounted for the highest proportions (68–78%) of heavy metals in sediment. Meanwhile, sediment in the centre of aquaculture water bodies (S2) contained more heavy metals than those in the perimeter (S1), but the released concentrations and rates (R release) of heavy metals from S1 were higher than those from S2. Moreover, the biomass, growth rate, specific growth rate, and nitrogen and carbon fixation rate of C. vulgaris increased with adding fish feed, whereas superoxide dismutase (SOD) and malondialdehyde (MDA) decreased. In addition, with C. vulgaris , influenced by the release process from sediment and the uptake by C. vulgaris , the concentration and R release of Mn, Pb, Cu, Mn, Cr and Cd from sediments coexisting with fish feed in water first increased and then decreased in general. The C. vulgaris biomass was significantly negatively related to Mn, Pb, Cu, Ni, Cr, and Cd and PO 4 3–P (P < 0.05), which was caused by the uptake of C. vulgaris and indicated that C. vulgaris biomass is easily affected by these factors. Accordingly, the input of residual fish feed and sediment should be controlled. [Display omitted] • Mn and Zn accounted for the highest proportions of heavy metals in sediment. • The toxicity of heavy metals from sediment to algae attenuated by fish feed. • Residual fish feed simulated the fixation of nitrogen and carbon by C. vulgaris. • C. vulgaris growth was easily affected by Mn, Pb, Cu, Ni, Cr, and Cd and PO 4 3–P. [ABSTRACT FROM AUTHOR]

Interactions of microplastics (MPs) biofilm with antibiotic resistance genes (ARGs) and antibiotics in aquatic environments have made microplastic biofilm an issue of keen scholarly interest. The process of biofilm formation and the degree of ARGs enrichment in the presence of antibiotic-selective pressure and the impact on the microbial community need to be further investigated. In this paper, the selective pressure of ciprofloxacin (CIP) and illumination conditions were investigated to affect the physicochemical properties, biomass, and extracellular polymer secretion of polyvinyl chloride (PVC) microplastic biofilm. In addition, relative copy numbers of nine ARGs were analyzed by real-time quantitative polymerase chain reaction (qPCR). In the presence of CIP, microorganisms in the water and microplastic biofilm were more inclined to carry associated ARGs (2–3 times higher), which had a contributing effect on ARGs enrichment. The process of pre-microplastic biofilm formation might have an inhibitory effect on ARGs (total relative abundance up to 0.151) transfer and proliferation compared to the surrounding water (total relative abundance up to 0.488). However, in the presence of CIP stress, microplastic biofilm maintained the abundance of ARGs (from 0.151 to 0.149) better compared to the surrounding water (from 0.488 to 0.386). Therefore, microplastic biofilm act as abundance buffer island of ARGs stabilizing the concentration of ARGs. In addition, high-throughput analyses showed the presence of antibiotic-resistant (Pseudomonas) and pathogenic (Vibrio) microorganisms in biofilm under different conditions. The above research deepens our understanding of ARGs enrichment in biofilm and provides important insights into the ecological risks of interactions between ARGs, antibiotics, and microplastic biofilm. [Display omitted] • Characteristics of PVC biofilm formation by different conditions were summarized. • Selective pressure of CIP had enrichment effect on ARGs in water and biofilm. • PVC biofilm created conditions for selective pressure to generate ARGs. • Biofilm maintained the abundance of ARGs better than the surrounding water. • Characterization of bacterial community composition in PVC biofilm was studied. [ABSTRACT FROM AUTHOR]

Drought conditions and nutrients loss have serious impacts on soil quality as well as crop yields in agroecosystems. New techniques are needed to carry out effective soil water and nutrient conservation and fertilizer application tools. Here, calcium alginate (CA) beads impregnated with ball-milled biochar (BMB) were investigated as a new type of water/nutrients retention agent. Both CA and Ca-alginate/ball milled biochar composite (CA-BMB) beads showed high kinetic swelling ratios in KNO 3 solution and low kinetic swelling ratios in water, indicating that CA-BMB beads have the potential to retain mineral nitrogen and nutrients by ion exchange. Pseudo-second-order kinetic model well-described the swelling kinetics of both beads in KNO 3 solution. Over a range of temperatures, the characteristics of dehydration suggested that impregnation with BMB improved the water holding capacity and postponed the dehydration time of Ca-alginate. The cumulative swelling and release characteristics of water, K + , and NO 3 − indicated that CA-BMB beads have great potential as a soil amendment to improve its nutrient retention and water holding capacity. [ABSTRACT FROM AUTHOR]

Over the past decade, biochar-supported nZVI composites (nZVI/biochar) have been developed and applied to treat various pollutants due to their excellent physical and chemical properties, especially in the field of chromium (VI) removal. This paper reviewed the factors influencing the preparation and experiments of nZVI/biochar composites, optimization methods, column experimental studies and the mechanism of Cr(VI) removal. The results showed that the difference in raw materials and preparation temperature led to the difference in functional groups and electron transfer capabilities of nZVI/biochar materials. In the experimental process, pH and test temperature can affect the surface chemical properties of materials and involve the electron transfer efficiency. Elemental doping and microbial coupling can effectively improve the performance of nZVI/biochar composites. In conclusion, biochar can stabilize nZVI and enhance electron transfer in nZVI/biochar materials, enabling the composite materials to remove Cr(VI) efficiently. The study of column experiments provides a theoretical basis for applying nZVI/biochar composites in engineering. Finally, the future work prospects of nZVI/biochar composites for heavy metal removal are introduced, and the main challenges and further research directions are proposed. [Display omitted] • NZVI/biochar is a highly efficient Cr(VI) removal composite. • Pyrolysis temperature and feedstock affect functional groups and electron transfer ability. • More efficient and stable effects can be achieved by adding stabilizer and element doping. • Flow rate is the key factor affecting removal efficiency in column experiment. • Multiple removal mechanisms coexist in nZVI/biochar Cr(VI) removal. [ABSTRACT FROM AUTHOR]

Chlorella vulgaris (C. vulgaris) was promising microalgae to simultaneously achieve biomass production, carbon dioxide (CO 2) fixation, nutrients removal and proteins production especially under different conditions of CO 2 gas and wastewaters. Results presented that maximal specific growth rate of C. vulgaris was 0.21–0.35 d−1 and 0.33–0.43 d−1 at 0.038% and 10% CO 2 respectively, and corresponding maximal CO 2 fixation rate was attended with 4.51–14.26 and 56.26–85.72 mg CO 2 ·L−1·d−1. C. vulgaris showed good wastewater removal efficiency of nitrogen and phosphorus at 10% CO 2 with 96.12%–99.61% removal rates. Nitrogen fixation amount achieved 41.86 mg L−1 when the initial NH 4 Cl concentration was set at 60 mg L−1 at 10% CO 2. Improved total protein (25.01–365.49 mg) and amino acids (24.56–196.44 mg) contents of C. vulgaris biomass was observed with the increasing of added CO 2 and ammonium concentrations. Moreover, the developed kinetic function of C. vulgaris growth depends on both phosphorus quota and nitrogen quota with correlation coefficient (R 2 ) ranged from 0.68 to 0.97. Computed maximal consumed nutrients concentrations (ΔC max) based on Logistic function are positively related to initial NH 4 +-N concentrations, which indicated that adding ammonium could stimulate the utilization of both phosphorus and nitrogen. Image 1 • CO 2 fixation and nutrients removal by C. vulgaris could be improved at 10% CO 2. • Adding CO 2 and NH 4 +-N promote the production of protein contents in C. vulgaris. • Kinetic function of C. vulgaris growth depends on both P quota and N quota. • Adding NH 4 +-N simulate the utilization of not only phosphorus but also nitrogen. • Higher NH 4 +-N concentrations reduced consumption rate of nitrogen by C. vulgaris. [ABSTRACT FROM AUTHOR]