Journal of environmental sciences最新文献

Paddy soils are an important source of atmospheric nitrous oxide (N₂O). However, numerous studies have focused on N₂O production during the soil tillage period, neglecting the N₂O production during the dry fallow period. In this study, we conducted an incubation experiment using the acetylene inhibition technique to investigate N₂O emission and reduction rates of paddy soil profiles (0-1 m) from Guangdong Province and Jinlin Province in China, with different heavy-metal pollution levels. The abundance and community structures of denitrifying bacteria were determined via quantitative-PCR and Illumina MiSeq sequencing of nosZ, nirK, and nirS genes. Our results showed that the potential N₂O emission rate, N₂O production rate, and denitrification rate have decreased with increasing soil vertical depth and heavy-metal pollution. More importantly, we found that the functional gene type of N₂O reductase switched with the tillage state of paddy soils, which clade Ⅱ nosZ genes were the dominant gene during the tillage period, while clade Ⅰ nosZ genes were the dominant gene during the dry fallow period. The heavy-metal pollution has less effect on the niche differentiation of the nosZ gene. The N₂O emission rate was significantly regulated by the genus Bradyhizobium, which contains both N₂O reductase and nitrite reductase genes. Our findings suggests that the nosZ gene of N₂O reductase can significantly impact the N₂O emission from paddy soils.

Amino acids (AAs) including D- and L- enantiomers are a group of organic nitrogen species in ambient aerosol. Due to the low abundances of AAs (level of ng/m³) and the matrix effects by coexistent components, it is challenging to quantify AA enantiomers in ambient aerosols especially under pollution conditions. In this study, we present an optimized method for analyzing AA enantiomers in atmospheric aerosol samples including a pretreatment process and the detection by high performance liquid chromatography coupled to a fluorescence detector (HPLC-FLD). Matrix effects caused by coexistent chemicals on AA enantiomers analysis in ambient aerosol samples were investigated especially for those collected in pollution episodes. The results revealed that the determination of AA enantiomers is significantly affected by the coexistent organic carbon (as a proxy of organic matter) and water-soluble ion of NH₄⁺. To remove the matrix effects, we applied a pretreatment using the solid phase extraction column coupled with alkaline adjustment to sample extract. After pretreatment, 18 AAs including 6 pairs of D- and L-enantiomers (i.e., leucine, isoleucine, valine, alanine, serine, and aspartic acid) can be successfully separated and quantified in aerosol samples by HPLC-FLD. The recoveries are in the range of 67%-106%. This method was successfully applied to the urban aerosol samples from pollution and non-pollution periods for AA enantiomers determination. We suggest that the concentrations of D-AAs and the ratio of D-AA/L-AA are indicative of the contribution of bacterial sources and the influence of biomass burning.

Antimicrobial resistance in the laying hen production industry has become a serious public health problem. The antimicrobial resistance and phylogenetic relationships of the common conditional pathogen Enterococcus along the laying hen production chain have not been systematically clarified. 105 Enterococcus isolates were obtained from 115 environmental samples (air, dust, feces, flies, sewage, and soil) collected along the laying hen production chain (breeding chicken, chick, young chicken, and commercial laying hen). These Enterococcus isolates exhibited resistance to some clinically relevant antibiotics, such as tetracycline (92.4%), streptomycin (92.4%), and erythromycin (91.4%), and all strains had multidrug resistance phenotypes. Whole genome sequencing characterized 29 acquired antibiotic resistance genes (ARGs) that conferred resistance to 11 classes of antibiotics in 51 pleuromutilin-resistant Enterococcus isolates, and lsa(E), which mediates resistance to pleuromutilins, always co-occurred with lnu(B). Alignments with the Mobile Genetic Elements database identified four transposons (Tn554, Tn558, Tn6261, and Tn6674) with several ARGs (erm(A), ant(9)-la, fex(A), and optrA) that mediated resistance to many clinically important antibiotics. Moreover, we identified two new transposons that carried ARGs in the Tn554 family designated as Tn7508 and Tn7492. A complementary approach based on conventional multi-locus sequence typing and whole genome single nucleotide polymorphism analysis showed that phylogenetically related pleuromutilin-resistant Enterococcus isolates were widely distributed in various environments on different production farms. Our results indicate that environmental contamination by antimicrobial-resistant Enterococcus requires greater attention, and they highlight the risk of pleuromutilin-resistant Enterococcus and ARGs disseminating along the laying hen production chain, thereby warranting effective disinfection.

Tributyltin (TBT), a common organotin environmental pollutant, may pose a threat to human development during critical early-life periods. We aimed to assess the neurodevelopmental intergenerational toxicity of early-life exposure to TBT and the protective effect of DNA methyl donor folic acid (FA). Specifically, after early-life exposure (1–21 days post-fertilization, dpf) to TBT (0, 1, 10 and 100 ng/L), zebrafish (Danio rerio) were cultured in clean medium until sexual maturity. The exposed females were mated with unexposed males to produce embryos (F1). The F1 generation were cultured (4–120 hours post-fertilization, hpf) with and without 1 mmol/L FA. The neurotoxic effects of early-life TBT exposure for zebrafish and their offspring (F1) were significantly enhanced anxiety and reduced aggression, decreased gene expression of DNA methyltransferase in the brain and increased serotonin levels in the body. Moreover, the intergenerational neurodevelopmental toxicity, as manifested in the F1 generation, was attenuated by FA supplementation. In summary, early-life TBT exposure led to intergenerational neurodevelopmental deficits in zebrafish, and DNA methyl donors had a protective effect on F1 neurodevelopment, which can inform the prevention and treatment of intergenerational neurotoxicity due to organotin pollutants.

The rapid deactivation of cost-effective MnO₂-based catalysts in humid air limits their application in practice, and the identification of the role of water in an oxidation process is significant for developing water-resistant MnO₂-based catalysts. Here, CuMnO₂ showed a 20.3% HCHO conversion in 10 hr at room temperature in humid air with relative humidity of 40%, but deactivated in 3 hr in dry air. The excellent activity and stability of HCHO oxidation in humid air were attributed to the positive effect of H₂O on HCHO oxidation to the H₂O-HOCH₂OH supermolecule assemblies via hydrogen bonds formed on CuMnO₂. H₂O-HOCH₂OH supermolecule assemblies tend to be oxidized to carbonate, which is further oxidized to CO₂. Furthermore, CuMnO₂ exhibited a much poorer activity of CO oxidation in humid air, but the CO conversion was still 100% in 10 hr in dry air. H₂O showed a competitive adsorption effect to CO on CuMnO₂. CuMnO₂ could be applied in HCHO elimination in humid air and CO elimination in dry air.

Perfluorinated compounds (PFCs) are toxic and widely present in the environment, and therefore effective adsorbents are required to remove PFCs from environmental water. In the present study, a new type of fluorinated biomass materials was synthesized via an ingenious fluorosilanization reaction. These adsorbents were applied for the adsorption of 13 typical PFCs, including perfluorocarboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs). By comparing their adsorption performance, Fluorinated cedar slag (FCS) was discovered to have the best absorption efficiency and enabled highly efficient enrichment of PFCs. The adsorption recovery of FCS with the investigated PFCs is greater than 90% under the optimal adsorption condition. Ascribed to the high affinity of F-F sorbent-sorbate interaction, FCS had good adsorption capacities of PFCs from aqueous solution, with the maximum adsorption capacity of 15.80 mg/g for PFOS and 10.71 mg/g for PFOA, respectively. Moreover, the adsorption time could be achieved in a short time (8 min). Using the FCS absorbent, an innovative FCS-solid phase extraction assisted with high performance liquid chromatography-electrospray-tandem mass spectrometry (FCS-SPE-HPLC-ESI-MS/MS) method was first developed to sensitively detect PFCs in the environmental water samples. The intra-day and inter-day recovery rates of the 13 compounds ranged from 90.7%-104.3%, with the RSD of 2.1%-4.7% (intra-day) and 2.5%-8.5% (inter-day), respectively. This research demonstrates the potential of the newly fluoro-functionalized plant biomass to adsorb PFCs from environmental water, with the advantages of high adsorption efficiencies, high anti-interference, easy operation and low economic cost.

Biomass burning has been known as one of main sources of Brown Carbon (BrC) in atmosphere. In this study, by controlling the combustion temperature at 250°C, 350°C, and 450°C, the methanol soluble organic carbon (MSOC) and methanol insoluble carbon (MISC) from pine wood burning was collected by impinger. UV–Vis, excitation emission matrix (EEM), TEM and FTIR spectra were applied to investigate the properties of BrC collected. For MSOC at 250°C and 350°C, all the spectral profiles of UV–Vis absorption and excitation emission matrix are almost the same, while the EEM of MSOC at 450°C are different from that of the other two. For MISC fluorescence was observed only in the case of 450°C. In the FTIR spectra, with the temperature increasing the peaks associated to the oxygen-contained functions was weakened, indicating the formation of the fluorophores with larger conjugated system, especially aromatic hydrocarbons. Our results show that biomass combustion at low temperature produces more oxygen-riched BrC, which possesses relatively lower light absorption, while at high temperature produces more aromatics hydrocarbons with relatively strong light absorption. The results of this work are helpful to trace the source of brown carbon and optimize biomass energy utilization.

Nowadays, a large number of compounds with different physical and chemical properties have been determined in soil. Environmental behaviors and source identification of pollutants in soil are the foundation of soil pollution control. Identification and quantitative analysis of potential pollution sources are the prerequisites for its prevention and control. Many efforts have made to develop methods for identifying the sources of soil pollutants. These efforts have involved the measurement of source and receptor parameters and the analysis of their relationships via numerical statistics methods. We have comprehensively reviewed the progress made in the development of source apportionment methodologies to date and present our synthesis. The numerical methods, such as spatial geostatistics analysis, receptor models, and machine learning methods are addressed in depth. In most cases, however, the effectiveness of any single approach for source apportionment remains limited. Combining multiple methods to address soil quality problems can reduce uncertainty about the sources of soil pollution. This review also constructively highlights the key strategies of combining mathematical models with the assessment of chemical profiles to provide more accurate source attribution. This review intends to provide a comprehensive summary of source apportionment methodologies to help promote further development.

Hazardous waste stream needs to be managed so as not to exceed stock- and rate-limited properties of its recipient ecosystems. The co-pyrolysis of Chinese medicine residue (CMR) and textile dyeing sludge (TDS) and its bio-oil, biochar, and ash quality and quantity were characterized as a function of the immersion of K₂CO₃, atmosphere type, blend ratio, and temperature. Compared to the mono-pyrolysis of TDS, its co-pyrolysis performance with CMR (the comprehensive performance index (CPI)) significantly improved by 33.9% in the N₂ atmosphere and 33.2% in the CO₂ atmosphere. The impregnation catalyzed the co-pyrolysis at 370°C, reduced its activation energy by 77.3 kJ/mol in the N₂ atmosphere and 134.6 kJ/mol in the CO₂ atmosphere, and enriched the degree of coke gasification by 44.25% in the CO₂ atmosphere. The impregnation increased the decomposition rate of the co-pyrolysis by weakening the bond energy of fatty side chains and bridge bonds, its catalytic and secondary products, and its bio-oil yield by 66.19%. Its bio-oils mainly contained olefins, aromatic structural substances, and alcohols. The immersion of K₂CO₃ improved the aromaticity of the co-pyrolytic biochars and reduced the contact between K and Si which made it convenient for Mg to react with SiO₂ to form magnesium-silicate. The co-pyrolytic biochar surfaces mainly included -OH, -CH₂, C=C, and Si-O-Si. The main phases in the co-pyrolytic ash included Ca₅(PO₄)₃(OH), Al₂O₃, and magnesium-silicate.

Antibiotic fermentation residue (AFR) is nutrient-rich solid waste generated from fermentative antibiotic production process. It is demonstrated that AFR contains high-concentration of remaining antibiotics, and thus may promote antibiotic resistance development in receiving environment or feeding farmed animals. However, the dominate microorganisms and antibiotic resistance genes (ARGs) in AFRs have not been adequately explored, hampering understanding on the potential antibiotic resistance risk development caused by AFRs. Herein, seven kinds of representative AFRs along their production, storage, and treatment processes were collected, and multiple methods including amplicon sequencing, metagenomic sequencing, and bioinformatic approaches were adopted to explore the biological characteristics of AFRs. As expected, antibiotic fermentation producer was found as the predominant species in raw AFRs, which were collected at the outlet of fermentation tanks. However, except for producer species, more environment-derived species persisted in stored AFRs, which were temporarily stored at a semi-open space. Lactobacillus genus, classified as Firmicutes phylum and Bacilli class, became predominant bacterial taxa in stored AFRs, which might attribute to its tolerance to high concentration of antibiotics. Results from metagenomic sequencing together with assembly and binning approaches showed that these newly-colonizing species (e.g., Lactobacillus genus) tended to carry ARGs conferring resistance to the remaining antibiotic. However, after thermal treatment, remaining antibiotic could be efficiently removed from AFRs, and microorganisms together with DNA could be strongly destroyed. In sum, the main risk from the AFRs was the remaining antibiotic, while environment-derived bacteria which tolerate extreme environment, survived in ARFs with high content antibiotics, and may carry ARGs. Thus, hydrothermal or other harmless treatment technologies are recommended to remove antibiotic content and inactivate bacteria before recycling of AFRs in pharmaceutical industry.