长江源区水文气象要素变化及其与大尺度环流因子关系研究

长江源区水文气象要素变化及其归因研究一直备受全球关注,现阶段研究多侧重于水文气象要素时空变化特征分析,针对长江源区水文气象要素与大尺度环流因子相互关系的研究不足。论文利用Mann-Kendall法、去趋势波动分析法和小波分析法,探究长江源区1957—2012年水文气象要素趋势性、波动性和周期性变化规律,分析水文气象要素与大尺度环流因子的相关关系,通过研究水汽通量揭示大尺度环流因子对水文气象要素变化的驱动机制。结果表明：20世纪90年代,长江源区气候暖干化,进入21世纪后,长江源区气候暖湿化趋势明显;长江源区水文气象要素序列具有正长程相关性,长江源区气候未来会继续呈现暖湿化变化趋势。长江源区水文气象要素都存在着1~5、10~24和25~45 a三种时间尺度周期变化规律。南亚季风是影响长江源区降水量和流量较为重要的大气环流因子,南亚季风驱动下的西南方向气流是长江源区主导气流和水汽来源。     

辽东湾潜在褐潮生物时空分布及环境关联

以18S rDNA V4区作为目标基因,利用自行设计的真核浮游植物鉴定引物V4（F/R）,结合高通量测序技术,对辽东湾2014年四季海水中真核浮游植物多样性进行了检测.结果发现了8种潜在褐潮生物：抑食金球藻、金牛微球藻、微拟球藻、颗粒微拟球藻、细小微胞藻、密球藻、普通小球藻、钙质角毛藻,其中前2种生态风险较高,主要分布在辽东湾西南、东南两侧.除抑食金球藻和细小微胞藻为混合营养型外,其他6种均为自养型.细小微胞藻丰度最高（平均161445个/L）,主要分布在秋季;其次是抑食金球藻、金牛微球藻（平均13912,13717个/L）,主要分布在春季;之后为钙质角毛藻、普通小球藻（平均5498,5234个/L）,主要分布在秋季;密球藻（平均1345个/L）,主要分布在夏季;微拟球藻、颗粒微拟球藻最少（平均56,44个/L）,冬季无分布.辽东湾潜在褐潮生物丰度与水温、水深、无机氮、N/P显著相关,其群落结构演替与环境因子关联性有待于进一步研究.     

Potential of secondary aerosol formation from Chinese gasoline engine exhaust

Light-duty gasoline vehicles have drawn public attention in China due to their significant primary emissions of particulate matter and volatile organic compounds(VOCs). However,little information on secondary aerosol formation from exhaust for Chinese vehicles and fuel conditions is available. In this study, chamber experiments were conducted to quantify the potential of secondary aerosol formation from the exhaust of a port fuel injection gasoline engine. The engine and fuel used are common in the Chinese market, and the fuel satisfies the China V gasoline fuel standard. Substantial secondary aerosol formation was observed during a 4–5 hr simulation, which was estimated to represent more than 10 days of equivalent atmospheric photo-oxidation in Beijing. As a consequence, the extreme case secondary organic aerosol(SOA) production was 426 ± 85 mg/kg-fuel, with high levels of precursors and OH exposure. The low hygroscopicity of the aerosols formed inside the chamber suggests that SOA was the dominant chemical composition. Fourteen percent of SOA measured in the chamber experiments could be explained through the oxidation of speciated single-ring aromatics. Unspeciated precursors, such as intermediate-volatility organic compounds and semi-volatile organic compounds, might be significant for SOA formation from gasoline VOCs. We concluded that reductions of emissions of aerosol precursor gases from vehicles are essential to mediate pollution in China.     

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.     

Long-term effects of sliver nanoparticles on the abundance and activity of soil microbiome

正Silver nanoparticles(Ag NPs)are among the most extensively used engineered nanomaterials because of their wellestablished antimicrobial and unique physicochemical properties(Yin et al.,2015).Applications of AgNPs have now been     

Relationship between physicochemical properties and dewaterability of hydrothermal sludge derived from different source

Sewage sludge (SS) and deinking sludge (DS) were used to comparatively study the hydrothermal dewatering of sludge with different components. For a better overview, an insight into the relationship between physicochemical properties and dewaterability of hydrothermal sludge was provided. Results found that not all kinds of sludge were suitably conditioned by hydrothermal treatment (HT) in term of the elevation of dewaterability. Higher hydrothermal temperature tended to enhance the dewaterability of SS rather than DS, which was supported by the variation of their physicochemical properties (including water distribution, bonding energy, extracellular polymeric substance (EPS), particles size, acid functional groups and zeta potential in this study). In addition, the changes in surface morphology suggested that the reverse effect of HT on sludge dewaterability was mainly due to their dewatering behavior. For SS, the destruction of EPS structure leaded to the release of bound water, thereby strengthening sludge dewatering. Conversely, “Bridging effect” generated by lignocellulose in DS was beneficial for sludge dewatering; however, the increasing hydrothermal temperature degraded part of lignocellulose and weakened “bridging effect”, finally resulting in worse dewaterability of DS.     

Investigating the bacterial community and amoebae population in rural domestic wastewater reclamation for irrigation

Reclamation of domestic wastewater for agricultural irrigation is viewed as a sustainable option to create an alternative water source and address water scarcity. Free-living amoebae(FLA), which are amphizoic protozoa, are widely distributed in various environmental sources. The FLA could cause considerable environmental and health risks. However, little information is available on the risk of these protozoa. In this study, we evaluated the feasibility using rural domestic wastewater for agricultural irrigation, and analyzed dynamic changes of the microbial community structure and FLA populations in raw and treated wastewater, as well as the phyllosphere and rhizosphere of lettuce production sites that were irrigated with different water sources. The bacterial community dynamics were analyzed by terminal restriction fragment length polymorphism(T-RFLP). The bacterial community structures in the influent were similar to that in the effluent, while in some cases relative abundances varied significantly. The populations of Acanthamoeba spp. and Hartmannella vermiformis in the anaerobically treated wastewater were significantly higher than in the raw wastewater. The vegetables could harbor diverse amoebae, and the abundances of Acanthamoeba spp. and H. vermiformis in the rhizosphere were significantly higher than in the phyllosphere. Accordingly, our studies show insight into the distribution and dissemination of amoebae in wastewater treatment and irrigation practices.     

Seasonal variation and size distribution of biogenic secondary organic aerosols at urban and continental background sites of China

Size-resolved biogenic secondary organic aerosols(BSOA) derived from isoprene and monoterpene photooxidation in Qinghai Lake, Tibetan Plateau(a continental background site) and five cities of China were measured using gas chromatography/mass spectrometry(GC/MS). Concentrations of the determined BSOA are higher in the cities than in the background and are also higher in summer than in winter. Moreover, strong positive correlations(R2= 0.44–0.90) between BSOA and sulfate were found at the six sites,suggesting that anthropogenic pollution(i.e., sulfate) could enhance SOA formation,because sulfate provides a surface favorable for acid-catalyzed formation of BSOA. Size distribution measurements showed that most of the determined SOA tracers are enriched in the fine mode( 3.3 μm) except for cis-pinic and cis-pinonic acids, both presented a comparable mass in the fine and coarse( 3.3 μm) modes, respectively. Mass ratio of oxidation products derived from isoprene to those from monoterpene in the five urban regions during summer are much less than those in Qinghai Lake region. In addition, in the five urban regions relative abundances of monoterpene oxidation products to SOA are much higher than those of isoprene. Such phenomena suggest that BSOA derived from monoterpenes are more abundant than those from isoprene in Chinese urban areas.     

Regionalization based on spatial and seasonal variation in ground-level ozone concentrations across China

Owing to the vast territory of China and strong regional characteristic of ozone pollution,it's desirable for policy makers to have a targeted and prioritized regulation and ozone pollution control strategy in China based on scientific evidences. It's important to assess its current pollution status as well as spatial and temporal variation patterns across China.Recent advances of national monitoring networks provide an opportunity to insight the actions of ozone pollution. Here, we present rotated empirical orthogonal function(REOF)analysis that was used on studying the spatiotemporal characteristics of daily ozone concentrations. Based on results of REOF analysis in pollution seasons for 3 years' observations, twelve regions with clear patterns were identified in China. The patterns of temporal variation of ozone in each region were separated well and different from each other, reflecting local meteorological, photochemical or pollution features. A rising trend in annual averaged Eight-hour Average Ozone Concentrations(O_3-8 hr) from 2014 to 2016 was observed for all regions, except for the Tibetan Plateau. The mean values of annual and 90 percentile concentrations for all 338 cities were 82.6 ± 14.6 and 133.9 ± 25.8 μg/m~3,respectively, in 2015. The regionalization results of ozone were found to be influenced greatly by terrain features, indicating significant terrain and landform effects on ozone spatial correlations. Among 12 regions, North China Plain, Huanghuai Plain, Central Yangtze River Plain, Pearl River Delta and Sichuan Basin were realized as priority regions for mitigation strategies, due to their higher ozone concentrations and dense population.     

石墨烯在防腐涂料中的研究进展及应用

简要叙述了石墨烯结构性能以及当前主流制备石墨烯的方法。概述了最近几年来石墨烯在防腐涂料中的研究进展情况,包括石墨烯在涂料中的添加量、分散技术、原位改性等对涂料性能的影响。研究表明,在涂层中分散均匀添加量适中的石墨烯可以对防腐涂料性能有较大的提升,探讨了石墨烯在防腐涂层中的应用机理,同时对石墨烯防腐涂料的应用发展进行了展望。