Polycyclic aromatic hydrocarbon and n-alkane pollution characteristics and structural and functional perturbations to the microbial community: a case-study of historically petroleum-contaminated soil

Characterization of the typical petroleum pollutants, polycyclic aromatic hydrocarbons (PAHs) and n-alkanes, and indigenous microbial community structure and function in historically contaminated soil at petrol stations is critical. Five soil samples were collected from a petrol station in Beijing, China. The concentrations of 16 PAHs and 31 n-alkanes were measured by gas chromatography-mass spectrometry. The total concentrations of PAHs and n-alkanes ranged from 973 ± 55 to 2667 ± 183 μg/kg and 6.40 ± 0.38 to 8.65 ± 0.59 mg/kg (dry weight), respectively, which increased with depth. According to the observed molecular indices, PAHs and n-alkanes originated mostly from petroleum-related sources. The levels of ΣPAHs and the total toxic benzo[a]pyrene equivalent (ranging from 6.41 to 72.54 μg/kg) might exert adverse biological effects. Shotgun metagenomic sequencing was employed to investigate the indigenous microbial community structure and function. The results revealed that Proteobacteria and Actinobacteria were the most abundant phyla, and Nocardioides and Microbacterium were the important genera. Based on COG and KEGG annotations, the highly abundant functional classes were identified, and these functions were involved in allowing microorganisms to adapt to the pressure from contaminants. Five petroleum hydrocarbon degradation-related genes were annotated, revealing the distribution of degrading microorganisms. This work facilitates the understanding of the composition, source, and potential ecological impacts of residual PAHs and n-alkanes in historically contaminated soil.

     

国家运输支撑力下的陆上丝绸之路运输通道风险测算方法

丝绸之路运输通道风险测算可有效分析通道风险因素,为国际运输宏观政策制定及风险管控提供理论支撑。针对25个国家的7条运输通道,结合文献分析法获取国家运输节点风险的影响因素,利用因子分析法量化综合风险;基于运输通道风险构成机制结合多维度的不均衡指数构建国家运输支撑力下的运输通道风险测度模型。结果表明:北线和西1通道风险最小,南线通道风险最大;运输通道风险测度受国家数目、国家参与程度及其影响力及国家风险状态影响;各运输通道内部与通道间均存在风险不均衡现象。     

考虑街区尺寸的应急救援路径选择仿真研究

为分析街区尺寸对应急救援车辆行程时间的影响，基于小（120 m）、中（264 m）、大（440 m）3种典型街区尺寸，将救援车辆行程时间分为街区内、外2部分，以总行程时间最小为目标，构建基于背景流量水平的救援车辆路径选择仿真模型。设置4种救援场景，分别求解各救援场景在不同街区尺寸下的最短路径时间、冗余度及复杂度。结果表明:街区尺寸对街区内、外部救援时间均有影响，而前者在救援路径距离较短、街区尺寸较大的路网中占据较大比例（可达50%以上）；救援路径包含路段的流量较小时，中、大街区尺寸路网表现类似，而高流量下大尺寸具备更优的救援时间；街区尺寸越小，救援路径冗余度与复杂度均越大。     

推荐管理措施情景下黄淮海地区旱地土壤固碳潜力模拟研究——以河南省获嘉县为例

农田土壤固碳不仅可以减缓气候变化,而且能够提高土壤质量。推荐管理措施,如少、免耕和秸秆还田等,具有促进农田土壤有机碳（SOC）增加的巨大潜力。旱地占中国农田面积的70%以上,在固定大气CO2方面可以发挥重要作用。本研究基于黄淮海地区的一个旱地土壤肥力长期监测点数据并运用Century模型模拟了监测期间（1998～2007）土壤有机碳动态变化。在此基础上,设计了1种基础管理措施情景和4种推荐管理措施情景并模拟了它们未来20年的固碳潜力。模拟结果表明,监测期间监测点土壤有机碳密度增加2.72 Mg.hm-2,年均增加0.27 Mg.hm-2。土壤有机碳的增加主要是因为氮肥施用量的增加。模型验证结果表明,Century模型很好地模拟了监测点土壤有机碳的动态变化。各推荐管理措施均具有较大的固碳潜力,其中50%秸秆还田是比少、免耕更有效的固碳措施,而少耕＋50%秸秆还田的固碳潜力最大。因此,在黄淮海地区旱地推广实施推荐管理措施是促进农田土壤固碳的有效策略,有助于减缓大气CO2浓度升高和保障国家粮食安全。     

A critical review on the technique and mechanism of microwave-based denitrification in flue gas

Microwave radiation has received extensive attention due to its significant thermal and non-thermal effects, and the development of MW-based denitrification in flue gas has become one of the most promising methods to avoid the defects of ammonia escape, high temperature and cost in traditional SCR. This review introduces the thermal and non-thermal effects of microwaves and divides MW-based denitrification methods into MW reduction and oxidation denitrification, systematically summarizes these denitrification methods, including MW discharge reduction, MW-induced catalytic reduction using active carbon, molecular sieves, metal oxides (transition metals, perovskites, etc.), MW-induced oxidation denitrification with and without additional oxidant, and discusses their removal pathway and mechanism. Finally, several research prospects and directions regarding the development of microwave-based denitrification methods are provided.     

柳林地区晚中新世 — 上新世红黏土磁性地层学研究

黄土高原巨厚的风成堆积蕴含丰富的古环境变化信息,是研究亚洲内陆干旱化与东亚季风演化的天然载体,对探讨全球气候变化具有重要意义.本文对黄土高原东部的柳林红黏土剖面开展的岩石磁学研究表明该红黏土层序磁性由磁铁矿、磁赤铁矿为主要磁性矿物.高分辨率的磁性地层学研究表明:柳林红黏土记录了C2An.1r?—?C3r的极性序列,结合磁性地层学结果和沉积速率的变化特征,计算得出柳林红黏土的年代跨度约为3.05?—?5.84 Ma.整体上柳林剖面从下至上表现为更高的磁化率值和更低的沉积速率,反映出与晚中新世相比,上新世早期和中期的夏季风有所增加和冬季风有所减弱.剖面中包含晚中新世至早上新世的红黏土沉积中发育的数层砾石层,可能是吕梁山隆升剥蚀的产物,经间歇性流水作用带入到柳林剖面的风成红黏土沉积中.     

Effect of Cu-based metal organic framework (Cu-MOF) loaded with TiO2 on the photocatalytic degradation of rhodamine B dye

Environmental Science and Pollution Research - Using copper nitrate trihydrate as the copper source, TiO2@Cu-MOF nanocomposites were prepared by a one-step crystallization method, and the effect of...     

Changes in ecological networks and eco-environmental effects on urban ecosystem in China’s typical urban agglomerations

Environmental Science and Pollution Research - Exploring the changes in ecological networks (ENs), its eco-environment effects and the differences in urban agglomerations in various urbanization...