粉煤灰对烟气中CO2的吸收特性及矿物相演变机理研究

粉煤灰矿化CO₂是一种极具前景的减少燃煤电厂CO₂排放的技术.然而,目前还缺乏从矿物学角度对碳酸化反应机理的详细认识.本研究选取了3种粉煤灰开展碳酸化实验和矿物学研究,考察碳酸化过程中温度对碳酸化能力及粉煤灰矿物学变化的影响.结果表明,在任一温度下,BJ粉煤灰的碳酸化率均高于YA和LY粉煤灰,这是由于BJ粉煤灰中硬石膏、钙铁石和无定形相等活性矿物相含量较高,LY粉煤灰缺少高活性的钙、镁结晶相.对YA粉煤灰而言,升高温度可显著提高透辉石、尖晶石、黑钙铁矿和方镁石的转化率.在碳酸化YA粉煤灰中同时检测出碳酸钙和碳酸镁/铁,说明除含钙相其他活性元素(Mg和Fe)也参与了碳酸化过程.因此,需要对每个粉煤灰原始材料的矿物学和操作温度进行具体的个案优化,以最大限度地提高固定CO₂能力和碳酸化率.结果还表明温度对不同晶型碳酸钙的形成具有重要作用.方解石在低温(40和80℃)下形成,而文石在高温(180和220℃)下形成.     

中国室内挥发性有机物污染特征

近年来室内空气污染问题频发,已引起全社会的广泛关注.挥发性有机物(volatile organic compounds,VOCs)是室内空气的主要污染物之一,其成分复杂,来源广泛,严重威胁人体健康.本文综述了中国近十年来室内VOCs在来源、浓度水平、影响因素及健康评价方面的研究进展.研究表明,室内建筑装修材料、人类活动及室外污染等来源都会影响VOCs的室内浓度;中国住宅内甲醛、苯等VOCs污染普遍存在,家具市场是甲醛污染最高的公共场所;VOCs浓度受到温湿度、通风和装修时间等因素影响;中国室内部分VOCs对人体健康影响评估值超过美国环保署可接受水平.调查更全面的室内VOCs数据,探索对各类因素影响机制,提出更有效降低VOCs对人体健康影响的措施将是未来室内空气治理重点发展方向.     

Chemical characterization and source apportionment of PM1 and PM2.5 in Tianjin, China: Impacts of biomass burning and primary biogenic sources

The submicron particulate matter (PM₁) and fine particulate matter (PM_2.5) are very important due to their greater adverse impacts on the natural environment and human health. In this study, the daily PM₁ and PM_2.5 samples were collected during early summer 2018 at a sub-urban site in the urban-industrial port city of Tianjin, China. The collected samples were analyzed for the carbonaceous fractions, inorganic ions, elemental species, and specific marker sugar species. The chemical characterization of PM₁ and PM_2.5 was based on their concentrations, compositions, and characteristic ratios (PM₁/PM_2.5, AE/CE, NO₃^?/SO₄^2?, OC/EC, SOC/OC, OM/TCA, K+/EC, levoglucosan/K⁺, V/Cu, and V/Ni). The average concentrations of PM₁ and PM_2.5 were 32.4 µg/m³ and 53.3 µg/m³, and PM₁ constituted 63% of PM_2.5 on average. The source apportionment of PM₁ and PM_2.5 by positive matrix factorization (PMF) model indicated the main sources of secondary aerosols (25% and 34%), biomass burning (17% and 20%), traffic emission (20% and 14%), and coal combustion (17% and 14%). The biomass burning factor involved agricultural fertilization and waste incineration. The biomass burning and primary biogenic contributions were determined by specific marker sugar species. The anthropogenic sources (combustion, secondary particle formation, etc) contributed significantly to PM₁ and PM_2.5, and the natural sources were more evident in PM_2.5. This work significantly contributes to the chemical characterization and source apportionment of PM₁ and PM_2.5 in near-port cities influenced by the diverse sources.     

Difference in calcium ion precipitation between free and immobilized Halovibrio mesolongii HMY2

Biomineralization has become a research focus in wastewater treatment due to its much lower costs compared to traditional methods. However, the low sodium chloride (NaCl)-tolerance of bacteria limits applications to only water with low NaCl concentrations. Here, calcium ions in hypersaline wastewater (10% NaCl) were precipitated by free and immobilized Halovibrio mesolongii HMY2 bacteria and the differences between them were determined. The results show that calcium ions can be transformed into several types of calcium carbonate with a range of morphologies, abundant organic functional groups (C-H, C-O-C, C=O, etc), protein secondary structures (β-sheet, α-helix, 3₁₀ helix, and β-turn), P=O and S-H indicated by P2p and S2p, and more negative δ¹³C_PDB (‰) values (-16.8‰ to -18.4‰). The optimal conditions for the immobilized bacteria were determined by doing experiments with six factors and five levels and using response surface method. Under the action of two groups of immobilized bacteria prepared under the optimal conditions, by the 10^th day, Ca²⁺ ion precipitation ratios had increased to 79%-89% and 80%-88% with changes in magnesium ion cencentrations. Magnesium ions can significantly inhibit the calcium ion precipitation, and this inhibitory effect can be decreased under the action of immobilized bacteria. Minerals induced by immobilized bacteria always aggregated together, had higher contents of Mg, P, and S, lower stable carbon isotope values and less well-developed protein secondary structures. This study demonstrates an economic and eco-friendly method for recycling calcium ions in hypersaline wastewater, providing an easy step in the process of desalination.     

装备外部冷却方法及在环境试验中的应用概述

首先简述了机载电子装备冷却的基本要素。其次,详细介绍了机载电子装备环控通风冷却、液体冷却方式的具体要求及不同的接口方式。然后,通过实例介绍了装备的不同冷却方式、方法及在实际中的应用。通过试验研究发现,不同的冷却方式不仅对机载电子装备本身有不同程度的影响,还对机载电子装备在环境试验过程中产生极大的影响,从而提出在实际应用中,应着重依据分析的内容考虑机载电子装备需采用的冷却方式,以达到最好的实施效果。     

Soil contamination with antibiotics in a typical peri-urban area in eastern China: Seasonal variation, risk assessment, and microbial responses

The prevalence and persistence of antibiotics in soils has become an emerging environmental issue and an increasing threat to soil security and global public health. The problem is more severe in areas undergoing rapid urbanization; however, the ecological risks of antibiotics, seasonal variability, and associated soil microbial responses in peri-urban soils have not been well-explored. The seasonal soil sampling campaigns were conducted in a typical peri-urban watershed in eastern China to investigate distribution of antibiotics. The results demonstrated higher mean concentrations of most antibiotic compounds in winter than in summer in peri-urban soils. The seasonal variations of norfloxacin, enrofloxacin, and ciprofloxacin were more significant than those of other antibiotics, due to their higher migration ability and bioavailability. An ecological risk assessment demonstrated that chlortetracycline, ciprofloxacin, doxycycline, and ofloxacin can pose high risks to soil microorganisms. Furthermore, the coexistence of multiple antibiotics obviously poses higher risks than individual compounds. A redundancy analysis demonstrated that tetracyclines mainly showed negative correlations with Firmicutes and Chloroflexi, and quinolones showed obviously negative correlations with Acidobacteria, Gemmatimonadetes, and Nitrospirae, suggesting potential inhibition from antibiotics on biological activities or biodegradation processes. However, the persistence of antibiotics in soil results in a significant decrease in bacterial diversity and a change in dominant species. Our results provide an overview of the seasonal variability of antibiotics and the associated effects on bacterial communities in peri-urban soils. The results can provide scientific guidance on decreasing soil contamination with antibiotics to enhance soil security in similar areas.     

Novel chitosan–ethylene glycol hydrogel for the removal of aqueous perfluorooctanoic acid

It is urgent to explore an effective removal method for perfluorooctanoic acid (PFOA) due to its recalcitrant nature. In this study, a novel chitosan-based hydrogel (CEGH) was prepared with a simple method using chitosan and ethylene glycol through a repeated freezing–thawing procedure. The adsorption of PFOA anions to CEGH agreed well to the Freundlich–Langmuir model with a maximum adsorption capacity as high as 1275.9?mg/g, which is higher than reported values of most adsorbents for PFOA. The adsorption was influenced by experimental conditions. Experimental results showed that the main removal mechanism was the ionic hydrogen bond interaction between carbonyl groups (COO^?) of PFOA and protonated amine (NH⁺) of the CEGH adsorbent. Therefore, CEGH is a very attractive adsorbent that can be used to remove PFOA from water in the future.     

Applications of magnetic nanoparticles in surface-enhanced Raman scattering (SERS) detection of environmental pollutants

Environmental pollution, a major problem worldwide, poses considerable threat to human health and ecological environment. Efficient and reliable detection technologies, which focus on the appearance of emerging environmental and trace pollutants, are urgently needed. Surface-enhanced Raman scattering(SERS) has become an attractive analytical tool for sensing trace targets in environmental field because of its inherent molecular fingerprint specificity and high sensitivity. In this review, we focused on the recent developments in the integration of magnetic nanoparticles(MNPs) with SERS for facilitating sensitive detection of environmental pollutants. An overview and classification of different types of MNPs for SERS detection were initially provided, enabling us to categorize the huge amount of literature that was available in the interdisciplinary research field of MNPs based SERS technology. Then, the basic working principles and applications of MNPs in SERS detection were presented. Subsequently, the detection technologies integrating MNPs with SERS that eventually were used for the detection of various environmental pollutions were reviewed. Finally, the advantages of MNP-basedSERS detection technology for environmental pollutants were concluded, and the current challenges and future outlook of this technology in practical applications were highlighted. The application of the MNPsbasedSERS techniques for environmental analysis will be significantly advanced with the great progresses of the nanotechnologies, optics, and materials.     

中国土壤污染防治管理体系思考

对中国土壤污染防治管理体系法律、法规、规范性文件及标准体系等进行了总结和分析,得出中国现行土壤污染防治管理体系存在执法依据空缺、系统性缺乏、可操作性差和协调性弱等问题.在此基础上,对中国土壤污染防治管理体系提出改善建议,如加快立法进度,土壤污染防治法需考虑与其他环境要素保护法律之间的衔接,明确各方责任,完善土壤标准体系等.尽快完善中国土壤污染防治管理体系,为中国土壤污染防治工作提供有力的法律保障.     

主观性在环境侵权案件证据和证明中的作用研究

法院在审理环境侵权案件时,往往依赖于专业鉴定、行政标准、专家意见等等客观依据来确定案件事实.但因为环境问题的复杂性,以及民事主体自身举证能力的限制,经常出现双方举证均不充分,法院无法基于现有事实和证据得出结论的情况.此时,法官应当发挥自身能动性,主动应用主观的、甚至是非科学性的因素和手段,包括容忍义务、经验法则、自由心证等等,这些因素无法被赋予客观的标准,它需要法官基于自身的理性以及经验,结合社会一般观念、习惯等因素进行判断.