城镇污水处理厂进出水对日本青鱂早期阶段亚慢性毒性效应

采用日本青鳉胚胎及幼鱼暴露评估污水处理厂进出水的综合毒性效应。水样采自广州市3个污水处理厂的进水口和出水口。96 h青鳉幼鱼急性毒性试验表明:6个水样均没有对青鳉幼鱼产生急性毒性效应。14 d胚胎暴露试验结果:3个污水处理厂的进水及1号和3号污水处理厂的出水均引起胚胎死亡,胚胎孵化率均低于70%且均与对照组产生了显著性差异(p0.05)。3个厂的进水和1号、2号厂出水的鱼苗畸形率与对照组也有显著差异(p0.05),其中3号厂进水鱼苗畸形率高达(33.73±8.94)%。而6个水样的胚胎孵化时间均与对照组无显著差异(p0.05),均在9 d左右。7 d鱼苗暴露试验结果:1、2、3号3个水厂进水的鱼苗死亡率分别是(30.16±2.75)%,(24.07±1.60)%,(37.90±4.77)%,与对照组产生明显差异(p0.05)。出水对鱼苗的致死效应明显低于进水,但出水对鱼苗的致死效应相对于对照组仍有显著差异(p0.05)。     

Diverse bacterial populations of PM2.5 in urban and suburb Shanghai,China

• Urban aerosols harbour diverse bacterial communities in Shanghai. • The functional groups were associated with nitrogen, carbon, and sulfur cycling. • Temperature, SO₂, and wind speed were key drivers for the bacterial community. Airborne bacteria play key roles in terrestrial and marine ecosystems and human health, yet our understanding of bacterial communities and their response to the environmental variables lags significantly behind that of other components of PM_2.5. Here, atmospheric fine particles obtained from urban and suburb Shanghai were analyzed by using the qPCR and Illumina Miseq sequencing. The bacteria with an average concentration of 2.12 × 10³ cells/m³, were dominated by Sphingomonas, Curvibacter, Acinetobacter, Bradyrhizobium, Methylobacterium, Halomonas, Aliihoeflea, and Phyllobacterium, which were related to the nitrogen, carbon, sulfur cycling and human health risk. Our results provide a global survey of bacterial community across urban, suburb, and high-altitude sites. In Shanghai (China), urban PM_2.5 harbour more diverse and dynamic bacterial populations than that in the suburb. The structural equation model explained about 27%, 41%, and 20%–78% of the variance found in bacteria diversity, concentration, and discrepant genera among urban and suburb sites. This work furthered the knowledge of diverse bacteria in a coastal Megacity in the Yangtze river delta and emphasized the potential impact of environmental variables on bacterial community structure.     

Volatile organic compounds in wintertime North China Plain: Insights from measurements of proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS)

The characteristics of wintertime volatile organic compounds (VOCs) in the North China Plain (NCP) region are complicated and remain obscure. VOC measurements were conducted by a proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS) at a rural site in the NCP from November to December 2018. Uncalibrated ions measured by PTR-ToF-MS were quantified and the overall VOC compositions were investigated by combining the measurements of PTR-ToF-MS and gas chromatography-mass spectrometer/flame ionization detector (GC-MS/FID). The measurement showed that although atmospheric VOCs concentrations are often dominated by primary emissions, the secondary formation of oxygenated VOCs (OVOCs) is non-negligible in the wintertime, i.e., OVOCs accounts for 42% ± 7% in the total VOCs (151.3 ± 75.6 ppbV). We demonstrated that PTR-MS measurements for isoprene are substantially overestimated due to the interferences of cycloalkanes. The chemical changes of organic carbon in a pollution accumulation period were investigated, which suggests an essential role of fragmentation reactions for large, chemically reduced compounds during the heavy-polluted stage in wintertime pollution. The changes of emission ratios of VOCs between winter 2011 and winter 2018 in the NCP support the positive effect of “coal to gas” strategies in curbing air pollutants. The high abundances of some key species (e.g. oxygenated aromatics) indicate the strong emissions of coal combustion in wintertime of NCP. The ratio of naphthalene to C8 aromatics was proposed as a potential indicator of the influence of coal combustion on VOCs.     

混凝处理工艺对再生水水质生物稳定性的影响

再生水在储存、输配过程中微生物的再生长现象给再生水的利用造成不利影响,因此,研究再生水的生物稳定性十分必要.本研究以可同化有机碳(AOC)表征再生水生物稳定性,考察了混凝处理对北京市再生水厂二级出水生物稳定性的影响.研究发现,二级出水中投加聚合氯化铝(PACl)剂量为20~120 mg·L~(-1)混凝处理后,水中溶解性有机碳(DOC)和不饱和有机物、含氮有机物(用UV254表征)的去除率分别为3%~30%和10%~36%,水样中荧光物质的去除效果不明显.分子量为3000~20000 Da的有机物容易被混凝过程去除,但分子量小于3000 Da的有机物在混凝过程中几乎不能被去除.二级出水经混凝处理后,AOC水平有升高的趋势.在PACl投加量为60 mg·L~(-1)时,混凝前后二级出水的AOC水平分别为48~485μg·L~(-1)和121~910μg·L~(-1),变化率为-4%~124%,说明混凝处理导致了水样水质生物稳定性降低.     

新冠疫情管控期间西安细颗粒物中碳组分浓度变化特征

于2019年1月27日—3月18日及2020年1月27日—3月18日对西安市细颗粒物(PM_2.5)的碳组分浓度进行了在线观测,对比分析了非疫情与疫情期间各常规污染因子、气象要素、PM_2.5中有机碳(OC)和元素碳(EC)的污染特征。结果表明：非疫情与疫情期间西安市的气象条件总体水平较为相近。疫情期间的二氧化硫(SO₂)、臭氧(O₃)浓度相对升高。重污染天气下,除PM_2.5外,其他污染物浓度均降低,说明疫情管制对重污染天气污染物浓度的削弱作用明显。疫情期间,PM_2.5中的OC组分浓度及占比有显著升高,与疫情期间的各类交通管制导致的机动车尾气排放量显著降低有关。另外,OC与EC的相关性较强,说明污染来源与人类日常生活有关。疫情期间西安市颗粒物中碳组分主要来自各类生物质燃烧,并且存在SOC污染,SOC在OC中的占比达到37.8%。疫情期间重污染天气下,SOC在OC中的占比达到87.5%,说明SOC对重污染天气OC的贡献较大。     

Tracing the impact of stack configuration on interface resistances in reverse electrodialysis by in situ electrochemical impedance spectroscopy

• RED performance and stack resistance were studied by EIS and LSV. • Interface resistance were discriminated from Ohmic resistance by EIS. • Impacts of spacer shadow effect and concentration polarization were analyzed. • Ionic short current reduced the power density for more cell pairs. • The results enabled to predict RED performance with different configurations. Reverse electrodialysis (RED) is an emerging membrane-based technology for the production of renewable energy from mixing waters with different salinities. Herein, the impact of the stack configuration on the Ohmic and non-Ohmic resistances as well as the performance of RED were systematically studied by using in situ electrochemical impedance spectroscopy (EIS). Three different parameters (membrane type, number of cell pairs and spacer design) were controlled. The Ohmic and non-Ohmic resistances were evaluated for RED stacks equipped with two types of commercial membranes (Type I and Type II) supplied by Fujifilm Manufacturing Europe B.V: Type I Fuji membranes displayed higher Ohmic and non-Ohmic resistances than Type II membranes, which was mainly attributed to the difference in fixed charge density. The output power of the stack was observed to decrease with the increasing number of cell pairs mainly due to the increase in ionic shortcut currents. With the reduction in spacer thickness from 750 to 200 µm, the permselectivity of membranes in the stack decreased from 0.86 to 0.79 whereas the energy efficiency losses increased from 31% to 49%. Overall, the output of the present study provides a basis for understanding the impact of stack design on internal losses during the scaling-up of RED.     

发达国家金属环境风险评估方法研究

金属进入环境后可能会对人体和生态环境造成潜在危害。目前发达国家金属环境风险评估体系已较为完善，而我国尚处于起步阶段。为了科学开展金属环境风险评估，以发达国家金属环境风险评估方法为研究对象，对美国环境保护局(United States Environmental Protection Agency, US EPA)、国际矿业与金属委员会(International Council on Mining and Metals, ICMM)等发达国家或国际组织发布的金属风险评估指南、导则中涉及的研究范围、关键评估要素等方面进行总结和分析。研究发现金属环境风险评估基于危害及效应评估、暴露评估及风险表征3个步骤，但由于在属性等方面的特殊性，在开展金属风险评估时需要考虑自然本底属性、营养属性、金属形态、金属混合物及其相互作用以及地域环境的差异性等要素，本文就上述要素提出了讨论与展望，以期为我国金属环境风险评估指南的建立提供参考。     

西藏自治区“十二五”和“十三五”环境空气质量变化特征

"十二五"以来中国先后颁布了一系列大气污染防治政策并实施相应的大气污染治理措施以提高环境空气质量。为研究西藏自治区"十二五"(2011-2015年)和"十三五"(2016 -2020年)时期环境空气质量变化状况,评估大气污染防治措施实施效果,笔者对2011-2020年西藏自治区7个城市(地区)主要大气污染物浓度和优良天数比例变化进行分析。结果表明:随着一系列大气污染防治措施的实施,西藏自治区环境空气质量显著提升,与"十二五"时期相比,"十三五"时期西藏自治区年平均优良天数比例由97.5%±2.0%提升至99.3%±0.4%,SO₂、 NO₂、 PM₁₀、 PM_2.5浓度年均值和CO 浓度第95百分位数均呈下降趋势,其中CO、PM₁₀和PM_2.5浓度下降幅度较大,O₃日最大8h滑动平均值第90百分位数略有上升。西藏自治区环境空气质量与人口、经济发展程度呈负相关关系。受污染源排放、气象条件和区域传输等因素影响,西藏自治区O₃浓度春、夏季较高,而其余污染物浓度冬季较高。