Exploration of the key functional strains from an azo dye degradation microbial community by DGGE and high-throughput sequencing technology

Environmental Science and Pollution Research - This study investigated a previously developed thermophilic microbial community with the ability to effectively degrade azo dyes. To identify the key...     

Migration of heavy metals and migration-degradation of phenanthrene in soil using electro kinetic-laccase combined remediation system

Abstract

In order to solve the problem of heavy metal-organic compound soil pollution, in this paper, we developed a highly efficient electro kinetic-laccase combined remediation (EKLCR) system. The results showed that the EKLCR system had an obvious migration effect on heavy metals (copper and cadmium) and good migration-degradation effect on phenanthrene. The migration rates of copper and cadmium were 48.3% and 40.3%, respectively. Especially, with the presence of laccase, the removal rate of phenanthrene on Cu²⁺-contaminated soil was higher than that of Cd²⁺-contaminated soil due to the significant effect of heavy metals on the enzymatic activity of laccase. The average migration-degradation rate of phenanthrene by EKLCR system was 45.4%. Finally, gas chromatography-mass spectrometry (GC/MS) was used to analyze the degradation intermediates of phenanthrene in the soil, which included 9,10-Phenanthrenequinone, phthalic acid, and 2,2-Biphenyldicarboxylic Acid. In addition, we give the possible degradation pathways of phenanthrene, 2,2-Biphenyldicarboxylic Acid is further degraded to produce phthalic acid. The products of the phthalic acid metabolic pathway are protocatechuic acid, pyruvic acid or succinic acid, the final products of these organic acids are carbon dioxide and water.     

Innovation for carbon mitigation: a hoax or road toward green growth? Evidence from newly industrialized economies

Environmental Science and Pollution Research - The research explores the nexus between technological innovation and green growth in nine newly industrialized (NI) countries for the period from 2000...     

Determination of propineb and its metabolites propylenethiourea and propylenediamine in banana and soil using gas chromatography with flame photometric detection and LC–MS/MS analysis

A sensitive and specific method for the determination of propineb and its metabolites, propylenethiourea (PTU) and propylenediamine (PDA), using gas chromatography with flame photometric detection (GC-FPD) and LC–MS/MS was developed and validated. Propineb and its metabolite residue dynamics in supervised field trials under Good Agricultural Practice (GAP) conditions in banana and soil were studied. Recovery of propineb (as CS₂), PDA and PTU ranged from 75.3 to 115.4% with RSD (n = 5) of 1.3–11.1%. The limit of quantification (LOQ) of CS₂, PDA and PTU ranged from 0.005 to 0.01 mg kg^?1, and the limit of detection (LOD) ranged from 0.0015 to 0.0033 mg kg^?1. Dissipation experiments showed that the half-life of propineb in banana and soil ranged from 4.4 to 13.3 days. PTU was found in banana with a half-life of 31.5–69.3 days, while levels of PDA were less than 0.01 mg kg^?1 in banana and soil. It has been suggested that PTU is the major metabolite of propineb in banana. The method was demonstrated to be reliable and sensitive for the routine monitoring of propineb and its metabolites in banana and soil. It also serves as a reference for the detection and monitoring of dithiocarbamates (DTCs) residues and the evaluation of their metabolic pathway.     

Biodegradation of waste refrigerator polyurethane by mealworms

● Waste refrigerator polyurethane (WRPU) was ingested and biodegraded by mealworms. ● The carbon in WRPU-based frass was lower than that in WRPU. ● Urethane groups in WRPU were broken down after ingestion by mealworms. ● Thermal stability of WRPU-based frass were deteriorated compared to that of WRPU. ● Gut microbiomes of mealworms fed using WRPU were distinct from that fed using bran. Refrigerator insulation replacement results in discarding a large amount of waste refrigerator polyurethane (WRPU). Insect larvae like mealworms have been used to biodegrade pristine plastics. However, knowledge about mealworms degrading WRPU is scarce. This study presents an in-depth investigation of the degradation of WRPU by mealworms using the micro-morphology, composition, and functional groups of WRPU and the egested frass characteristics. It was found that the WRPU debris in frass was scoured, implying that WRPU was ingested and degraded by mealworms. The carbon content of WRPU-based frass was lower than that of WRPU, indicating that mealworms utilized WRPU as a carbon source. The urethane groups in WRPU were broken, and benzene rings’ C=C and C–H bonds in the isocyanate disappeared after being ingested by mealworms. Thermal gravimetric-differential thermal gravimetry analysis showed that the weight loss temperature of WRPU-based frass was 300 °C lower than that of WRPU, indicating that the thermal stability of WRPU deteriorated after being ingested. The carbon balance analysis confirmed that carbon in the ingested WRPU released as CO₂ increased from 18.84 % to 29.80 %, suggesting that WRPU was partially mineralized. The carbon in the mealworm biomass ingesting WRPU decreased. The possible reason is that WRPU does not supply sufficient nutrients for mealworm growth, and the impurities and odor present in WRPU affect the appetite of the mealworms. The microbial community analysis indicated that WRPU exerts a considerable effect on the gut microorganism of mealworms. These findings confirm that mealworms degrade WRPU.     

基于改进蝴蝶算法和社会力模型的多出口疏散模型研究*

为提高多出口场景下行人疏散效率和精度,基于蝴蝶算法和社会力模型,提出一种新的应急疏散仿真路径规划方法。在原有社会力模型中,考虑距离出口远近及行人所处位置拥挤度对运动过程中期望速度的影响,引入速度调节因子,描述行人在疏散中的期望速度变化;针对蝴蝶算法中后期收敛速度慢和易陷入局部最优的缺陷,提出自适应感知概率参数以增强局部搜索和全局搜索之间的平衡;在每轮迭代结束时引入迭代局部搜索策略,扰动局部最优解获得中间状态,并重新搜索上述中间状态得到全局最优解。研究结果表明:提出的应急疏散仿真路径规划方法在多出口环境下能够更有效地利用出口资源,提高疏散效率。     

Formation of halonitromethanes from methylamine in the presence of bromide during UV/Cl2 disinfection

The UV/Cl₂ process is commonly used to achieve a multiple-barrier disinfection and maintain residuals. The study chose methylamine as a precursor to study the formation of high-toxic halonitromethanes (HNMs) in the presence of bromide ions (Br⁻) during UV/Cl₂ disinfection. The maximum yield of HNMs increased first and then decreased with increasing concentration of Br⁻. An excessively high concentration of Br⁻ induced the maximum yield of HNMs in advance. The maximum bromine incorporation factor (BIF) increased, while the maximum bromine utilization factor (BUF) decreased with the increase of Br⁻ concentration. The maximum yield of HNMs decreased as pH value increased from 6.0 to 8.0 due to the deprotonation process. The BUF value remained relatively higher under an acidic condition, while pH value had no evident influence on the BIF value. The maximum yield of HNMs and value of BUF maximized at a Cl₂:Br⁻ ratio of 12.5, whereas the BIF value remained relatively higher at low Cl₂:Br⁻ ratios (2.5 and 5). The amino group in methylamine was first halogenated, and then released into solution as inorganic nitrogen by the rupture of C-N bond or transformed to nitro group by oxidation and elimination pathways. The maximum yield of HNMs in real waters was higher than that in pure water due to the high content of dissolved organic carbon. Two real waters were sampled to verify the law of HNMs formation. This study helps to understand the HNMs formation (especially brominated species) when the UV/Cl₂ process is adopted as a disinfection technique.     

Antimony transformation and mobilization from stibnite by an antimonite oxidizing bacterium Bosea sp. AS-1

Soils and waters are heavily contaminated by antimony in Xikuangshan（XKS） mine area.It is widely accepted that oxidative dissolution of sulfide minerals and aqueous dissolution are the most prevalent geochemical mechanisms for the release of Sb to the environment.Bosea sp. AS-1 is an antimonite-oxidizer isolated from the mine slag in Xikuangshan Sb mine. Whole genome sequencing revealed the presence of multiple sulfur-oxidizing genes,antimony（Sb） metabolism genes and carbon fixation genes in AS-...     

Sources of ambient non-methane hydrocarbon compounds and their impacts on O3 formation during autumn, Beijing

The field observation of 54 non-methane hydrocarbon compounds (NMHCs) was conducted from September 1 to October 20 in 2020 during autumn in Haidian District, Beijing. The mean concentration of total NMHCs was 29.81 ± 11.39 ppbv during this period, and alkanes were the major components. There were typical festival effects of NMHCs with lower concentration during the National Day. Alkenes and aromatics were the dominant groups in ozone formation potential (OFP) and OH radical loss rate (L_OH). The positive matrix factorization (PMF) running results revealed that vehicular exhaust became the biggest source in urban areas, followed by liquefied petroleum gas (LPG) usage, solvent usage, and fuel evaporation. The box model coupled with master chemical mechanism (MCM) was applied to study the impacts of different NMHCs sources on ozone (O₃) formation in an O₃ episode. The simulation results indicated that reducing NMHCs concentration could effectively suppress O₃ formation. Moreover, reducing traffic-related emissions of NMHCs was an effective way to control O₃ pollution at an urban site in Beijing.     

A facial strategy to efficiently improve catalytic performance of CoFe2O4 to peroxymonosulfate

Cobalt iron spinel (CoFe₂O₄) has been considered as a good heterogeneous catalysis to peroxymonosulfate (PMS) in the degradation of persistent organic pollutants due to its magnetic properties and good chemical stability. However, its catalytic activity needs to be further improved. Here, a facial strategy, “in-situ substitution”, was adopted to modify CoFe₂O₄ to improve its catalytic performance just by suitably increasing the Co/Fe ratio in synthesis process. Compared with CoFe₂O₄, the newly synthesized Co_1.5Fe_1.5O₄, could not only significantly improve the degradation efficiency of phenol, from 50.69 to 93.6%, but also exhibited more effective mineralization ability and higher PMS utilization. The activation energy advantage for phenol degradation using Co_1.5Fe_1.5O₄ was only 44.2 kJ/mol, much lower than that with CoFe₂O₄ (127.3 kJ/mol). A series of related representations of CoFe₂O₄ and Co_1.5Fe_1.5O₄ were compared to explore the possible reasons for the outstanding catalytic activity of Co_1.5Fe_1.5O₄. Results showed that Co_1.5Fe_1.5O₄ as well represented spinel crystal as CoFe₂O₄ and the excess cobalt just partially replaced the position of iron without changing the original structure. Co_1.5Fe_1.5O₄ had smaller particle size (8.7 nm), larger specific surface area (126.3 m²/g), which was more favorable for exposure of active sites. Apart from the superior physical properties, more importantly, more reactive centers Co (Ⅱ) and surface hydroxyl compounds generated on Co_1.5Fe_1.5O₄, which might be the major reason. Furthermore, Co_1.5Fe_1.5O₄ behaved good paramagnetism, wide range of pH suitability and strong resistance to salt interference, making it a new prospect in environmental application.