贵州农村污水典型抗生素污染水平及生态风险

抗生素残留物是一种新兴的微污染物,广泛存在于各种环境介质及生物样品中,长期暴露在抗生素环境会对人体健康、生态环境产生一定的潜在威胁。由于农村污水排放量逐渐增大、农村地区对抗生素的不合理使用以及受经济、地理地形的限制大部分农村地区都缺乏完整的污水收集管网和污水治理设施,进而导致抗生素通过多种途径进入农村环境,可能会对农村生态环境产生一定的环境风险。为了解贵州农村污水中抗生素的污染水平及处理后污水对环境的影响,作者采用固相萃取—液相色谱—串联质谱(SPE-LC-MS)联用技术,选取贵州省3处典型农村地区,对农村污水治理设施进出水中典型抗生素(包括6种磺胺类、3种四环素类、1种喹诺酮类抗生素)的浓度水平进行分析。结果表明,3处农村污水治理设施进水和出水中均检出不同程度的抗生素,浓度范围分别在ND～417.57 ng/L和ND～253.68 ng/L,其中土霉素浓度最高,进出水的浓度分别为417.57、253.68 ng/L;其次是氧氟沙星,在进出水中的最高浓度分别为278.75、183.73 ng/L。3处农村污水治理设施对抗生素的去除率在-58.32%～45.52%,对目标抗生素的去除率较低。与国内外其他地区农村污水相比,所选地区的进出水中抗生素的浓度较高。通过生态风险评估发现,经处理后的污水中均含有一种RQ≥1的抗生素物质,并且发现氧氟沙星为处理后污水中的高风险污染物,污水的排放会对环境造成一定的生态风险。     

A novel state-of-charge-based method for plug-in hybrid vehicle electric distance analysis validated with actual driving data

Mitigation and Adaptation Strategies for Global Change - Promoting Plug-In Hybrid Vehicles (PHEVs) is viewed as a promising strategy to mitigate the energy consumption and greenhouse gas...     

Well-to-wheels greenhouse gas and air pollutant emissions from battery electric vehicles in China

Mitigation and Adaptation Strategies for Global Change - Electric vehicles (EVs) play a crucial role in addressing climate change and urban air quality concerns. China has emerged as the global...     

Optimal range of plug-in electric vehicles in Beijing and Shanghai

Both China’s national subsidy policies for plug-in electric vehicles (PEVs) purchasers and passenger cars corporate average fuel consumption and new vehicle credit regulation (dual-credit policy) favor long-range 300+ km battery electric vehicles (BEVs) and 80+ km plug-in hybrid electric vehicles (PHEVs). However, these electric vehicles tend to have lower energy efficiency and higher purchase and operation costs. Vehicle with larger batteries can also be less equitable because the subsidies are often provided to more expensive vehicles and wealthier owners. This study takes advantage of a novel dataset of daily driving data from 39,854 conventional gasoline vehicles in Beijing and 4999 PHEVs in Shanghai to determine the optimal range of BEVs and PHEVs within their respective cities. We simulate a model to explore ranges with which PEVs emit less GHGs than that of a baseline hybrid and conventional gasoline vehicle while ensuring that all daily travel demands are met. Our findings indicate that in both cities, the optimal ranges to balance cost and travel demand for BEVs are 350 km or less and for PHEVs are 60 km or less in Beijing and 80 km or less in Shanghai. We also find that to minimize carbon dioxide (CO₂) emissions, the ranges are even lower 10 km in Beijing and 30 km in Shanghai. Our study suggests that instead of encouraging long-range PEVs, governments should subsidize PEV models with shorter ranges. Parallel efforts should also be made to both increase renewable energy over fossil fuels and expand charging facilities. Although individual mobility demand varies, the government could reduce occasional long-distance driving by subsidizing alternative transportation choices. Providing week-long driving trials to consumers before their purchases may help decrease the demand of very long range PEVs by alleviating the range anxiety through a learning process.

     

南京八卦洲农用地表层土壤重金属分布特征及风险评价

为查明南京八卦洲土壤重金属污染物类型及其影响范围,于2017年12月在洲内采集了471个表层土壤样品,测定了pH及As、Cd、Cr、Cu、Hg、Ni、Pb、Zn等8种重金属元素浓度,采用单因子指数法、内梅罗综合指数法和潜在生态危害指数法进行了污染风险评价。研究结果表明:As、Cd、Cr、Cu、Hg、Ni、Pb和Zn平均浓度分别为10.66、0.32、86.74、43.25、0.10、40.34、33.50和108.33 mg·kg-1,除As、Hg元素外,其余6种元素均超过南京市背景值,出现大范围的富集;Cd元素为研究区主要污染物,绝大部分为Ⅱ级轻微污染,均分布于八卦洲服务区附近的中、酸性土覆盖区,需做好安全利用措施。从全区来看研究区大部分农用地土壤处于安全生产级别,仅有少部分区域处于Ⅱ级和Ⅲ级风险水平,总体上潜在生态危害较低。     

基于铁锰泥的除砷吸附剂性能比较及吸附机理

为解决反冲洗铁锰泥粉末吸附剂（BSPA）使用后难以泥水分离问题,将除铁锰水厂生物滤池产生的反冲洗泥制成颗粒吸附剂（GA）和磁性粉末吸附剂（MPA）,并对BSPA、GA和MPA的除砷性能进行了比较,通过SEM、TED、XRD、BET、FTIR等技术对3种材料进行了表征,寻找3种吸附剂之间除砷性能差异的根源.结果表明,BSPA、GA和MPA对As （V）的最大吸附容量分别为40.980,5.048,8.694mg/g,改性后的吸附材料GA和MPA对砷的吸附能力下降.BSPA是一种以纤铁矿为主的无定形结构混合物,并混有针铁矿和结晶度差的水铁矿,GA的XRD图谱中出现石英晶体和少量赤铁矿晶体的衍射峰,而MPA的主要成分为结晶程度较高的磁赤铁矿.3种材料中均存在有利于吸附的含羟基官能团.BSPA、MPA和GA的比表面积分别为253.150,238.660,43.803m²/g.物相改变且结晶程度增加、表面羟基减少和比表面积降低是导致GA和MPA的砷吸附容量比BSPA低的主要因素.     

兰州市南山季节性土壤微生物特征及影响因素

为了探究不同季节和不同植被类型对土壤微生物分布的影响,以兰州市南山不同海拔的两种植被类型为研究对象,采用稀释涂布平板法测定了土壤微生物的季节动态变化特征.结果表明：研究区内细菌数量占微生物总数的96.22%~99.80%,远高于真菌和放线菌数量.土壤微生物类群随季节变化呈现明显差异,其总数整体表现为夏季最高,为89.22×10⁶cfu/g soil,分别是春、秋、冬季的12.02、3.28、2.74倍,其中夏季细菌数量最高,真菌与放线菌数量均在春季达到最大值.人工林样地土壤微生物数量略低于荒坡,环境因子中土壤含水量和有机碳含量高于荒坡.随着海拔的升高,pH值逐渐上升,土壤温度、有机碳与全氮含量逐渐下降,土壤微生物总数则呈现先减少后增加的趋势.相关分析表明,不同季节各微生物类群与环境因子的相关系数各有不同,春季放线菌与有机碳,秋季真菌与有机碳、全氮均呈极显著正相关（P<0.01）.冗余分析表明,环境因子中有机碳与第一物种轴的相关系数最高,为0.520,说明土壤有机碳含量是影响土壤微生物类群分布的主导因素.     

Nanoencapsulation of hexavalent chromium with nanoscale zero-valent iron: High resolution chemical mapping of the passivation layer

Solid phase reactions of Cr(Ⅵ) with Fe(0) were investigated with spherical-aberration-corrected scanning transmission electron microscopy(Cs-STEM) integrated with X-ray energy-dispersive spectroscopy(XEDS). Near-atomic resolution elemental mappings of Cr(Ⅵ)–Fe(0) reactions were acquired. Experimental results show that rate and extent of Cr(Ⅵ) encapsulation are strongly dependent on the initial concentration of Cr(Ⅵ) in solution. Low Cr loading in nZⅥ(1.0 wt%) promotes the electrochemical oxidation and continuous corrosion of n ZⅥ while high Cr loading(1.0 wt%) can quickly shut down the Cr uptake. With the progress of iron oxidation and dissolution, elements of Cr and O counter-diffuse into the nanoparticles and accumulate in the core region at low levels of Cr(Ⅵ)(e.g., 10 mg/L). Whereas the reacted n ZⅥ is quickly coated with a newly-formed layer of 2–4 nm in the presence of concentrated Cr(Ⅵ)(e.g., 100 mg/L). The passivation structure is stable over a wide range of pH unless pH is low enough to dissolve the passivation layer. X-ray photoelectron spectroscopy(XPS) depth profiling reconfirms that the composition of the newly-formed surface layer consists of Fe(Ⅲ)–Cr(Ⅲ)(oxy)hydroxides with Cr(Ⅵ) adsorbed on the outside surface. The insoluble and insulating Fe(Ⅲ)–Cr(Ⅲ)(oxy)hydroxide layer can completely cover the n ZⅥ surface above the critical Cr loading and shield the electron transfer. Thus, the fast passivation of nZⅥ in high Cr(Ⅵ) solution is detrimental to the performance of nZⅥ for Cr(Ⅵ) treatment and remediation.     

The effects of autophagy on vascular endothelial cells induced by airborne PM2.5

The purpose of this study was to examine the direct toxicity of PM2.5 collected from Beijing on human umbilical vein endothelial cells(HUVEC). A Cell Counting Kit 8(CCK8) assay demonstrated that PM2.5 exposure decreased the proliferation of HUVECs in a dosedependent manner. We also found that PM2.5 exposure induced autophagy in HUVECs, as evidenced by:(1) an increased number of double-membrane vesicles;(2) enhanced conversion and punctuation of the microtubule-associated protein light chain 3(LC3); and(3) decreased levels of the selective autophagy substrate p62 in a time-dependent manner.Furthermore, promoting autophagy in PM2.5-exposed HUVECs with rapamycin increased the cell survival rate, whereas inhibiting autophagy via 3-methyladenine significantly decreased cell survival. These results demonstrate that PM2.5 exposure can induce cytotoxicity and autophagy in HUVECs and that autophagy play a protective role against PM2.5-induced cytotoxicity. The findings of the present study imply a direct toxic effect of PM2.5 on HUVECs and provide novel insight into the mechanism of cardiovascular diseases caused by PM2.5 exposure.     

Effect of TiO2 nanoparticle aggregation on marine microalgae Isochrysis galbana

TiO_2 nanoparticles(NPs) could adversely impact aquatic ecosystems. However, the aggregation of these NPs could attenuate this effect. In this work, the biological effects of TiO_2 NPs on a marine microalgae Isochrysis galbana were investigated. The aggregation kinetics of TiO_2 NPs under different conditions was also investigated to determine and understand these effects. Results showed that, though TiO_2 NPs had no obvious impact on the size and reproducibility of algal cells under testing conditions, they caused a negative effect on algal chlorophyll, which led to a reduction in photosynthesis. Furthermore, fast aggregation of TiO_2 NPs occurred under all conditions, especially at the pH close to the p Hzpc. Increasing ionic strength and NP concentration also enhanced the aggregation rate.The aggregation and the following sedimentation of TiO_2 NPs reduced their adverse effects on I. galbana.