船舶塑料垃圾热解特性及动力学分析

利用热重分析(TGA)研究船舶塑料垃圾在不同升温速率和不同气氛下的热解特性,并得到了热解动力学参数。结果表明,船舶塑料垃圾的热解过程主要有3个阶段,比一般塑料热解复杂;随着升温速率增大,最大热解速率和最大热解速率温度等热解特性参数也增大,反应变得更剧烈;N2/CO2比为4∶1时,热解反应进行得最完全,固体残留率最少。动力学分析表明,采用3个连续一级反应模型能很好地拟合实验数据;不同的升温速率和气氛比对反应各阶段活化能均有不同程度的影响。     

Effect of flue gas recirculation on nitric oxide (NO) emissions during the coal grate-fired process

Flue gas recirculation (FGR) is a low nitrogen oxide (NO_X) combustion technology. The present study used standard gas to simulate the cycle gas (the main ingredients of which are oxygen (O₂), nitrogen (N₂), and carbon dioxide (CO₂)). The coal grate-fired process was divided into three zones, namely (1) volatilization zone, (2) main combustion zone, and (3) char combustion and burn-out zone. The effects of FGR on coal combustion and NO emissions were investigated in these zones of a unit-boiler experimental system. An industrial test was then conducted on a chain boiler that previously used FGR. Data showed that if the cycle gas was directed into the furnace from the volatilization zone, the curve of the coal surface temperature moved backwards, the temperature peak increased, and coal ignition was delayed. When the FGR rate was 20%, NO emissions/g coal was 41.8% less than in the absence of FGR, in the overall combustion process except for the volatilization zone. An industrial test demonstrated that FGR decreased the NO emissions and incomplete-combustion loss of gas. NO and carbon monoxide (CO) emissions were reduced by 26.9 and 38%, respectively. These observations may prove to be beneficial in reducing ambient air pollution and saving energy.     

过硫酸钠-过氧化钙修复多环芳烃污染土壤

采用过硫酸钠-过氧化钙双氧化体系修复多环芳烃(PAHs)污染土壤.通过单因素实验考察了过硫酸钠浓度、过氧化钙质量分数和n(柠檬酸):n(硫酸亚铁)等对土壤中PAHs降解率的影响.通过响应面分析确定,在过氧化钙质量分数为2.7％、过硫酸钠浓度为0.62 mol/L、n(柠檬酸):n(硫酸亚铁)=1:1时,PAHs降解率最...     

稻草经超声波辅助预处理后酶解过程的动力学研究

在功率为120 W、处理时间为30 min的条件下,分别对稻草进行超声波辅助酸碱预处理,与传统化学预处理(碱-预处理、酸-预处理)后稻草的主要化学组成相比较,结果表明超声波技术辅助酸碱预处理可以更为有效地去除半纤维素和木质素,从而提高了稻草基质中纤维素的相对含量,有利于缩短稻草水解时间。在一系列实验研究的基础上,建立了稻草酶水解动力学模型。结果表明,分别经碱、超声波-碱、酸、超声波-酸预处理的稻草在糖化过程中的模型参数(米氏常数KM,速率常数k和抑制常数KI)均不相同,KM分别为17.55、14.14、15.29和15.08 g/L;k分别为15.30、21.32、13.40和15.42 h-1;抑制常数KI变化不明显分别为2.31、2.08、1.81和1.85 g/L。模型及实验方法简便可靠,有较好的拟合性,对稻草酶水解过程工程放大及过程控制都具有一定的参考价值。     

Temporal trends (2005-2009) of PCDD/Fs, PCBs, PBDEs in rice hulls from an e-waste dismantling area after stricter environmental regulations

Primitive e-waste dismantling activities have been of increasing concern due to serious environmental and human health problems, and therefore authorities in China have strengthened the regulations on illegal e-waste recycling activities. In this work, we used rice hull as a passive sampler and investigated temporal trends of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) in areas near e-waste recycling sites after the stricter regulations. Furthermore, the distribution patterns and composition profiles of these contaminants were also discussed. The average concentrations of the three groups of persistent organic pollutants (POPs) in rice hulls have markedly decreased during the period of 2005-2009. Specifically, from 12.9 (average value in 2005) to 0.37 pg WHO-TEQ/g (dry weight, dw) (in 2009) for PCDD/Fs, 47.6 (2005) to 7.10 ng g⁻¹ dw (2009) for PCBs, and 2.51 (2005) to 0.89 ng g⁻¹, dw (2009) for PBDEs. The significant decrease of combustion markers 2,3,4,7,8-PeCDF, 1,2,3,6,7,8HxCDF and PCB126, and the PCDD/PCDF ratio from 1:9 (2005) to 7:3 (2009) is likely a result of stricter regulations on open combustion activities. This study suggests that stricter control measures, strengthened laws and regulations and more environmental friendly techniques could be effective measures in reducing the release and formation of related POPs in typical e-waste dismantling sites, and these measures could further improve the quality of the environment and health of the local inhabitants.     

农业非点源污染模型研究概况

在阐述非点源污染的概念、特点的基础上，对国内外农业环境非点源污染模型研究现状进行了综述。通过分类比较几个常用模型，分析了国内外研究存在的不足讨论了非点源研究的未来发展趋势。     

镉对小鼠骨生物力学及成骨细胞MG-63的影响

为了探讨镉对骨的影响及机制,选取7周龄C57BL/6J小鼠给予氯化镉2 mg.kg-1腹腔注射,每周2次,染毒4周后进行了骨力学参数的测量.结果显示,暴露组股骨的最大弯曲应力及弹性模量降低,骨灰干重比下降.体外结果显示,氯化镉(CdCl2)的暴露影响人成骨肉瘤细胞MG-63的细胞形态、活力及增殖,并且呈剂量依赖性.因此,氯化镉暴露可导致小鼠骨量下降和骨力学性能下降,并对成骨细胞有明显的毒性.     

典型人冠状病毒的环境行为及传播方式

过去二十年来,冠状病毒引起的严重传染性疾病时有发生,急性呼吸系统综合征冠状病毒(SARS-CoV)引起的重症急性呼吸综合征(SARS)、中东呼吸综合征冠状病毒(MERS-CoV)引起的中东呼吸综合征(MERS)以及新型呼吸道冠状病毒(SARS-CoV-2)引发的严重新冠肺炎(COVID-19)疫情,均对公共卫生防控形成巨大挑战.尤其是正在发生的COVID-19疫情,更是遍及全球,造成严重的健康危害和巨大的经济损失.本文总结了几种典型高致病性人冠状病毒在大气、水和土壤环境中的行为特征及主要传播方式,为进一步了解冠状病毒的传播能力和风险提供科学依据.尽管现在仍有新的认识不断出现,探讨SARS-CoV-2冠状病毒环境行为及传播方式,可为疫情控制和冠状病毒污染医疗垃圾等废弃物的处理提供科学指导,具有重要的现实意义.     

Possible role of extracellular vesicles in exogenous chemical exposure-associated health concern

Extracellular vesicles(EVs) are mediators of intercellular message communication by transferring lipids, proteins, genetic materials, and are therefore involved in a wide spectrum of physiological or pathological processes. Exogenous chemicals exposure may affect the function of EVs at the biogenesis, secretion, transport or reception stage, which could further result in abnormal information communication between cells, and thus induce toxicity and diseases. This review briefly explores the role of EVs in chemical exposure-associated health concern and progressive diseases.     

Comprehensive characterization of oil refinery effluent-derived humic substances using various spectroscopic approaches

Refinery effluent-derived humic substances (HS) are important for developing refinery effluent reclamation techniques and studying the environmental chemistry of wastewater effluents. In this study, dissolved organic matter (DOM) from refinery effluent was concentrated using a portable reverse osmosis (RO) system. HS were isolated from RO retentates with XAD-8 resin. A variety of approaches such as specific UV absorbance at 254nm (SUV(254)), elemental analysis, size exclusion chromatography (SEC), solid-state cross polarization magic angle spinning (13)C nuclear magnetic resonance spectrometry ((13)C CPMAS NMR), Fourier transform infrared spectrometry (FTIR), and electrospray ionization/ion trap/mass spectrometry (ESI/ion trap/MS) were employed for characterization of HS. The portable RO system exhibited high yield and recovery of DOM for concentrating refinery effluent. The concentration of dissolved organic carbon (DOC) in the refinery effluent was 9.9mg/l, in which humic acids (HA) and fulvic acids (FA) accounted for 2.3% and 34.6%, respectively. Elemental and SUV(254) analyses indicated relative high amounts of aliphatic structures and low amounts of aromatic structures in refinery effluent-derived HS. Refinery effluent-derived HS displayed lower molecular weight than natural HS. The number-average molecular weight (M(n)) and the weight-average molecular weight (M(w)) of HA were 1069 and 2934, and those of FA were 679 and 1212 by SEC, respectively. By ESI/ion trap/MS, the M(n) and the M(w) of FA were 330 and 383. Four kinds of carbon structures (aliphatic, aromatic, heteroaliphatic, and carboxylic carbons) were found in refinery effluent-derived HS by (13)C NMR analysis. The quantitative results support the interpretation that these HS are rich in aliphatic carbons and poor in aromatic carbons. Proteinaceous materials were identified by FTIR analysis in refinery effluent-derived HS.