淹水时长对3种丛枝菌根(AM)真菌侵染2种湿地植物的影响

以不同淹水时长为唯一影响因子,以香蒲(Typha orientalis)和水稻(Oryza sativa L.)为宿主植物,选用Glomus属的3种AM真菌(F1菌:Glomus intraradices;F2菌:Glomus versiforme;F3菌:Glomus etunicatum),研究淹水时长对3种AM真菌侵染2种湿地植物的影响,以期为阐明淹水对湿地植物AM结构与功能的影响提供参考.结果表明,淹水时间越长,3种AM真菌对2种植物的侵染率越低;相同淹水时间下,F3菌对香蒲、F1菌和F2菌对水稻的侵染率高于其他菌.3种AM真菌的侵染结构分析表明,菌丝侵染是2种湿地植物形成AM的主要途径,而丛枝和泡囊贡献较小;淹水时间越长,香蒲的菌丝侵染比例越高,但水稻的菌丝侵染比例没明显变化规律;淹水时间越长,2种植物的丛枝侵染比例越低,不淹水时最高.AM真菌产孢数分析表明,淹水时间越长,AM真菌的产孢数越多;相同淹水时长下,F3菌产孢数最多.2种植物的湿重变化表明,3种AM真菌在长时间淹水条件下仍能明显促进香蒲地上和地下部分的生长,但对水稻的生长影响不明显.本研究表明,淹水时长影响AM真菌对湿地植物的侵染水平和侵染结构,淹水条件下AM真菌对湿地植物生长仍有促进作用,但这受宿主植物对AM真菌的菌根依赖性影响.所以,在湿地植物上应用AM真菌时,应考虑植物的菌根依赖性和淹水时长对接种效果的影响.     

二硫代氨基甲酸盐絮凝处理模拟油田聚合物驱采油废水的效果研究

在碱性条件下,端氨基聚醚Jeffamine-T403与二硫化碳反应合成了二硫代氨基甲酸盐型絮凝剂DTC(T403).考察了DTC(T403)对模拟聚合物驱采油废水的絮凝除油性能,研究了DTC(T403)、水解聚丙烯酰胺(HPAM)、Fe2+和Fe3+的投加量以及pH值对除油效果的影响.结果发现,DTC(T403)与Fe2+络合形成的网状螯合物通过网捕作用取得良好的絮凝除油效果;HPAM的存在影响絮凝除油效果;在同时投加Fe2+和DTC(T403)且二者的投加量分别为10mg/L和25mg/L的条件下,HPAM含量在0～900mg/L范围和含油量约300mg/L的模拟水样经絮凝处理后其含油量均可降到10mg/L以下.DTC(T403)的絮凝除油效果受pH値的影响,在pH7.5条件下可取得良好的除油效果.DTC(T403)适用于含Fe2+的聚合物驱采油废水的处理.     

Preliminary investigation on cytotoxicity of fluorinated polymer nanoparticles

As well-known persistent organic pollutants(POPs), organofluorine pollutants such as perfluorooctane sulfonate(PFOS) have been proven to be bioaccumulated and harmful to health. However, toxicological assessment of organofluorinated nanoparticles, which have emerged as a novel tool for biomedical and industrial applications, is lacking, to the best of our knowledge. To assess the biological effects and health risk of fluorinated nanoparticles,trifluoroethyl aryl ether-based fluorinated poly(methyl methacrylate) nanoparticles(PTFEPMMA NPs) were synthesized with various fluorine contents(PTFE-PMMA-1 NPs 12.0 wt.%,PTFE-PMMA-2 NPs 6.1 wt.% and PTFE-PMMA-3 NPs 5.0 wt.%), and their cytotoxicity was investigated in this study. The in vitro experimental results indicated that the cytotoxicity of PTFE-PMMA NPs was mild, and was closely related to their fluorine(F) contents and Fcontaining side chains. Specifically, the cytotoxicity of PTFE-PMMA NPs decreased with increasing F content and F-containing side chains. After exposure to PTFE-PMMA NPs at a sublethal dose(50 μg/m L) for 24 hr, the phospholipid bilayer was damaged, accompanied by increasing permeability of the cell membrane. Meanwhile, the intracellular accumulation of reactive oxygen species(ROS) occurred, resulting in the increase of DNA damage, cell cycle arrest and cell death. Overall, the PTFE-PMMA NPs were found to be relatively safe compared with typical engineered nanomaterials(ENMs), such as silver nanoparticles and graphene oxide, for biomedical and industrial applications.     

黄河三角洲不同淹水条件下芦苇和盐地碱蓬凋落物的分解与重金属归还特征

以黄河三角洲芦苇(Phragmites australis)和盐地碱蓬(Suaeda salsa)的凋落物为研究对象,研究不同淹水条件下芦苇和盐地碱蓬凋落物的分解与重金属的归还特征。结果表明:两种淹水条件下,盐地碱蓬凋落物的失重率均高于芦苇凋落物;潮汐淹水条件下芦苇和盐地碱蓬凋落物的失重率均高于短暂淹水处理。在两种淹水条件下,经过分解后芦苇凋落物中As、Cr和Cu的含量增加,潮汐淹水条件下芦苇凋落物的各金属含量均高于短期淹水处理。盐地碱蓬凋落物经过分解后,各重金属含量总体上呈上升变化趋势,潮汐淹水条件下的盐地碱蓬凋落物中As、Cu和Pb的含量均高于短期淹水处理。两种淹水条件下芦苇和盐地碱蓬凋落物中的Pb和Zn,在分解期间均发生了不同程度的释放。研究结果有助于理解潮汐作用对黄河三角洲芦苇和盐地碱蓬凋落物分解和重金属归还的影响。     

Improved Bankfull Discharge Prediction Using 2‐Year Recurrence‐Period Discharge1

Abstract:  Knowledge of bankfull discharge (Q_bf) is essential for planners, engineers, geomorphologists, environmentalists, agricultural interests, developments situated on flood prone lands, surface mining and reclamation activities, and others interested in floods and flooding. In conjunction with estimating Q_bf, regionalized bankfull hydraulic geometry relationships, which relate Q_bf and associated channel dimensions (i.e., width, depth, and cross‐section area) to drainage basin area (A_da), are often used. This study seeks to improve upon the common practice of predicting Q_bf using A_da exclusively. Specifically, we hypothesize that predictions of Q_bf can be improved by including estimates of the 2‐year recurrence‐period discharge (Q₂) in regression models for predicting Q_bf. For testing this hypothesis, we used Q_bf estimates from 30 reports containing data for streams that span 34 hydrologic regions in 16 states. Corresponding values of Q₂ and A_da were compiled from flood‐frequency reports and other sources. By comparing statistical measures (i.e., root mean squared error, coefficient of determination, and Akaike’s information criterion), we determined that predicting Q_bf from Q₂ rather than A_da yields consistently better estimates of Q_bf. Other principal findings are (1) data are needed for at least 12 sites in a region for reliable hydraulic geometry model selection and (2) an approximate range of values for Q_bf/Q₂ is 0.10‐3.0.     

基于洪水过程的农业洪灾变化遥感快速评估模型及其应用

洪涝灾情的准确测度需要同时兼顾淹没区的面积大小和淹水时长信息。利用淹没区内由水和作物等多种地物所组成的"复合水体"不同于水体的波谱时间变化特性,将不同洪灾时期的水体指数和植被指数进行信息复合,以有效凸显水体和洪涝淹没区之间的影像差异,据此进行了灾初期、峰期和中后期等3个时次受淹范围的有效识别。在此基础上,根据洪涝灾情随着淹没时长而加重以及灾区内淹水时长非均匀分布的特性,建立基于淹没时长的受淹面积不等权参与的洪灾扩展动态度指数(Variation Index of Flood,VIF)和区域灾情比较指数(Comparison Index of Flood Disaster,CIFD)两种模型,并将模型应用于鄱阳湖区2016年夏季农业洪涝灾害的时空变化遥感监测。结果显示,应用上述两种模型不仅可以准确获取鄱阳湖区本次农业洪涝灾情的演变趋势,而且能够方便地对比分析区域内不同地方的受灾程度。鄱阳湖区在2016年6月23日~7月25日期间的洪涝灾情具有由弱增强再趋弱的特征,其VIF指数由初始阶段(6月23日~7月9日)的3.75降至后续阶段(7月9日~7月23日)的1.29;鄱阳县是研究区内受灾最严重的区域,其CIFD指数值居于研究区内各受灾县市之首,该县受灾总面积以及多次被淹的灾区面积均高于其他县市。     

城市绿化屋顶的微气候调节与径流削减效应研究

快速城市化与气候变化双重作用下,热岛效应与城市内涝成为最为突出的城市环境问题。绿化屋顶因能有效利用闲置屋面添緑、帮助城市缓解热岛和暴雨径流而受到关注。以往研究较多探讨单种气象条件下、单个小面积实验型绿化屋面的气候水文调节功能,本研究基于夏秋两季的微气候水文观测数据,定量分析不同气象条件下5种典型绿化屋顶的降温和径流削减效应。首先选择晴朗、多云、降雨3种典型夏日天气条件,分析草坪、裸土、菜地、小面积花园、大面积花园5种类型绿化屋顶与对照光屋顶之间的温度差日变化规律,探讨绿化屋顶热效应强度及时空特征;其次,选择暴雨、大雨、中雨及小雨4次典型降雨,分析大面积草坪与花园型绿化屋顶上的降雨-滞蓄过程及径流削减率。研究结果表明:绿化屋顶降温与升温效应并存,晴朗无风天气条件下,距离屋面10 cm和150 cm两个高度上,绿化屋顶最高可降低气温5.3℃和2.5℃,多云及降雨天气条件下降温强度下降,升温时段延长;白天草坪与裸土上的大气温度高于对照光屋顶,其它绿化屋顶的温度低于对照屋顶;夜间5个绿化屋顶的大气温度均低于对照屋顶,且降温效应按照大面积花园、草坪、小面积花园、裸土、菜地的顺序递减。绿化屋顶径流削减效益与绿化类型及降雨强度密切相关,花园型绿化对一次典型暴雨、大雨、中雨、小雨的径流削减率分别为50.8%、78%、100%、100%,简易型绿化的4次径流削减率分别为24.3%,58.6%,98.2%和100%。研究结果可为同气候区其他城市绿化屋顶环境设计及管理提供一定参考价值。     

Does community resilience mitigate loss and damage from climaterelated disasters? Evidence based on survey data

Policy-makers view community resilience as fundamental to mitigating loss and damage from climate-related disasters. Although energy has been devoted to defining resilience, less effort has been devoted to analysing the effects of resilience on loss and damage, which is critical in places with limited capacity for adaptation. We use survey data to develop a composite index of community resilience in Fiji and then evaluate the extent to which community resilience mitigates loss and damage. We find that community resilience is negatively correlated with damages over which human intervention may be effective, but not with damages over which intervention is less effective, suggesting that community resilience may limit impacts. We further find that this result holds for a cyclone (about which communities had substantial advance warning) but not for river flooding (for which communities had little advanced warning), suggesting that early warning is necessary for community resilience to become responsive.     

Physically Based,Hydrologic Model Results Based on Three Precipitation Products1

Abstract: The main objective of the study is to examine the accuracy of and differences among simulated streamflows driven by rainfall estimates from a network of 22 rain gauges spread over a 2,170 km² watershed, NEXRAD Stage III radar data, and Tropical Rainfall Measuring Mission (TRMM) 3B42 satellite data. The Gridded Surface Subsurface Hydrologic Analysis (GSSHA), a physically based, distributed parameter, grid‐structured, hydrologic model, was used to simulate the June‐2002 flooding event in the Upper Guadalupe River watershed in south central Texas. There were significant differences between the rainfall fields estimated by the three types of measurement technologies. These differences resulted in even larger differences in the simulated hydrologic response of the watershed. In general, simulations driven by radar rainfall yielded better results than those driven by satellite or rain‐gauge estimates. This study also presents an overview of effects of land cover changes on runoff and stream discharge. The results demonstrate that, for major rainfall events similar to the 2002 event, the effect of urbanization on the watershed in the past two decades would not have made any significant effect on the hydrologic response. The effect of urbanization on the hydrologic response increases as the size of the rainfall event decreases.