Revisiting nitrous acid (HONO) emission from on-road vehicles: A tunnel study with a mixed fleet

Nitrous acid (HONO) is an important precursor of OH radicals in the atmosphere. In urban areas, emissions from vehicles are the main source of air pollutants, including reactive nitrogen. Previously reported emission ratios of HONO (HONO/NO_x) from vehicles were measured in the late 1990s and need to be updated due to the significant changes in emission control technologies. We measured the emission ratio of a fleet of vehicles (38% diesel on average) from March 11 to 21, 2015, in a road tunnel in Hong Kong. The emission ratio of 1.24% (±0.35%) obtained is greater than the commonly adopted 0.8% or 0.3%. The elevated emission ratio is found to be related to the presence of vehicles equipped with diesel particle filters (DPFs). Positive correlation between HONO and black carbon (BC) shows that HONO and BC were emitted together, while the lack of correlation or even anticorrelation between HONO/NO_x and BC indicates that the BC-mediated conversion of NO₂ to HONO in the dark was insignificant in the immediate vicinity of the emission sources.

Implications: Vehicular emission is a key source for HONO in the urban atmosphere. However, the most commonly used emission ratio HONO/NO_x in modeling studies was measured more than 15 years ago. Our tunnel study suggests that a mixed fleet nowadays has a higher emission ratio, possibly because of the diesel particle filter (DPF) retrofit program and the growing share of Euro IV or more advanced diesel vehicles. Our study also provides new insight into the role of black carbon in HONO formation from vehicles.     

东营市海岸带区域综合承载力评估

随着人类对海岸带开发强度的不断提高,海岸带资源、环境问题日益突出,海岸带可持续发展成为人类共识,海岸带区域综合承载力研究作为该区域可持续发展的基础性研究,可以为海岸带区域合理开发与管理提供重要理论支撑。本文选取东营市海岸带为研究区域,以海岸带湿地遥感解译数据、浅海水质监测数据及社会经济统计数据为数据源,运用状态空间法计算了研究区2010—2014年海岸带区域的综合承载力;对东营市与潍坊市、滨州市的海岸带区域综合承载力进行了比较分析;预测了2016—2020年东营市海岸带区域综合承载力;依据研究结果探讨了海岸带可持续利用的未来途径。结果表明:在过去的2010—2014年和预测的2016—2020年东营市海岸带区域综合承载力均处于超载状态,但总趋势是向好的;同时,2010—2014年东营市海岸带在吸引外资、港口发展、海岸带生态系统服务价值、浅海海域水环境方面具有明显优势,但社会公共服务投入不平衡、不稳定。与2016—2020年东营市海岸带区域综合承载力预测结果相比较而言,2011年东营市海岸带区域综合承载力超载最明显,与该年环境压力大和社会投入不足有关。2014年东营市各县区海岸带区域综合承载力均处于超载状态,广饶县超载最明显;同时各县区自然、社会、经济发展水平差异较大,市辖区社会经济指标优于各县区。东营市海岸带区域综合承载力相比潍坊市、滨州市在资源、环境、生态方面具有明显优势,但在社会支撑方面投入不足,因此可以通过保持资源、生态优势,弥补社会投入不足等措施提高东营市海岸带可持续利用水平。     

硫酸盐型厌氧氨氧化的反应机理及启动过程影响因素综述

硫酸盐型厌氧氨氧化(S-ANAMMOX)可将废水中的氮硫元素同时去除,避免了氨氮、硫酸盐分别处理时过程不稳定、去除效率低等不足,且不产生二次污染。但该反应的启动耗时长以及机理不明确影响了其应用。本文在探讨S-ANAMMOX反应机理的基础上,对反应器、污泥源、填料、碳源及运行条件等启动过程影响因素进行了阐述,并对今后的研究做出了展望。指出:应在量化反应产物的基础上深入对反应机理和功能微生物特性的研究;分析反应器、污泥源等启动因素的差异性;促进S-ANAMMOX在实际废水处理中的应用。     

Roles of glutathione and L-cysteine in the biomimetic green synthesis of CdSe quantum dots

Biological synthesis of quantum dots (QDs) as an environmental-friendly and facile preparation method has attracted increasing interests. However, it is difficult to distinguish the roles of bio-thiols in QDs synthesis process because of the complex nature in organisms. In this work, the CdSe QDs synthesis conditions in organisms were reconstructed by using a simplified in vitro approach to uncover the roles of two small bio-thiols in the QDs formation. CdSe QDs were synthesized with glutathione (GSH) and L-cysteine (Cys) respectively. Compared with Cys at the same molar concentration, the CdSe QDs synthesized by GSH had a larger and broader particle size distribution with improved optical properties and crystal structure. Furthermore, quantum chemical calculations indicate that the stronger Cd²⁺ binding capacity of GSH contributed a lot to the CdSe QDs formation despite of the greater capability Cys for selenite reduction. This work clearly demonstrates the different roles of small thiols in the Cd²⁺ stabilization in the environment and biomimetic QDs synthesis process.

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Intelligent bio-conversion of food waste by housefly larvae: a small-scale case in Nanjing,China

Journal of Material Cycles and Waste Management - This NOTE summarizes process, practical case, and perspectives of intelligent bioconversion via insect (housefly larvae) for treating food waste...     

Reasonable water replenishment strategies can improve the fermentation efficiency and bacterial community of sheep manure composting on the Qinghai–Tibet Plateau

Journal of Material Cycles and Waste Management - The dry climate of the Qinghai–Tibet Plateau causes the rapid loss of moisture in composting piles, which affects dynamics of the composting...     

加速溶剂萃取—气相色谱法测定土壤中的类二噁英多氯联苯

采用加速溶剂萃取(ASE)—气相色谱法测定土壤中的12种类二噁英多氯联苯。在萃取温度100℃、萃取时间15min、萃取溶剂正己烷与丙酮的体积比1∶1、萃取试样量3g的最佳实验条件下,12种类二噁英多氯联苯的加标回收率为88.5%～109.8%,相对标准偏差为1.1%～6.7%。对小麦田实际土壤试样进行测定,共检出8种类二噁英多氯联苯,含量为50～671pg/g。     

磷酸三丁酯络合萃取邻氨基苯酚及工业废水预处理研究

根据络合萃取的原理,考虑了萃取剂与稀释剂之间的作用,选择磷酸三丁酯(TBP)为萃取剂,以正辛醇和氯仿为极性稀释剂、四氯化碳和煤油为非极性稀释剂,对邻氨基苯酚(OAP)稀溶液进行了探讨,讨论了体系的pH、TBP的浓度、稀释剂种类对萃取分配比(D)的影响.结果表明,TBP主要通过与OAP的中性分子键合作用实现萃取;D值的变化与中性分子的摩尔分数有关,pH是影响D的主要因素;稀释剂的极性对OAP的萃取影响较大,在萃取剂体积分数为10%～30%时,其萃取能力为TBP-正辛醇＞TBP-煤油＞TBP-四氯化碳＞TBP-氯仿;在萃取剂体积分数为30%～50%时,萃取能力为TBP-煤油＞TBP-正辛醇＞TBP-四氯化碳＞TBP-氯仿.进而以30%TBP-煤油为萃取剂,对工业含OAP废水进行了错流萃取实验.实验表明,该方法可以对工业OAP废水进行有效的(94.7%)预处理;工业废水中的甲醇、乙醇,对萃取有较大影响.     

革用水性聚氨酯的研究

为适应可持续发展的需要,有必要寻找水性聚氨酯产品来替代原有产品。通过大量研究试验,对不同原材料进行对比筛选,已经开发出一批在模最、透湿量、耐挠等许多性能方面都较好的溶剂型聚氨酯浆料的水性浆料。     

饮用水中蓝藻毒素污染研究进展

日趋严重的水体富营养化已成为全球性的环境问题,藻类及藻毒素给传统净水工艺带来了诸多不利影响,增加了水处理难度.对饮用水中蓝藻毒素去除技术进行了具体的论述,系统分析了各种技术的去除效果和局限性,并对藻毒素研究前景进行了展望.