膜生物反应器处理高浓度含酚废水研究

将膜生物反应器(MBR)用于高浓度含酚废水的处理中,探讨了进水中苯酚浓度、水力停留时间和污泥浓度对膜生物反应器处理含酚废水效果的影响。实验结果表明:经过42d驯化后,可以在高浓度含酚废水中正常运行,MBR系统对COD和氨氮的去除率分别可达98%和80.6%。当苯酚浓度为134mg/L时,处理的最佳水力停留时间为3h,最佳污泥浓度(MLSS)为7367mg/L。     

Spatial and temporal variability of agricultural pollutants in an agricultural headwater stream within a multipond system, southeastern China

The spatial and temporal variability of nutrients and suspended solids were investigated for two years in a 1.8 km agricultural headwater stream, located by Chaohu Lake, southeastern China. The stream form was greatly modified by human activities into channelized, pond and estuary shapes. The stream could be divided into 4 channelized reaches(1.3 km), a pond reach(0.15 km) and 3 estuary reaches(0.36 km). It was found that nutrients and TSS concentrations in the stream showed temporal variability, and higher concentrations occurred in months with high precipitation and intensive agricultural activities. And, retention of total nitrogen ( TN ), nitrate ( NO3-N ),ammonium( NH4^ -N) and total suspended solids (TSS) predominantly occurred in the pond reach and estuary reaches with larger width and low current velocity. Pollutants retained in these reaches accounted for more than 50% of those retained in whole stream. The retention mostly happened in the rain-runoff events and it was 7 to 27 times than that in base flow. The results showed that the channelized reach was the most important source for pollutants release under either runoff or base flow, and its release accounted for more than 90% of whole stream release.There was a high spatial variability of nutrients retention in different channelized reaches. The channelized reach directly discharging into the pond did always retain nutrients and TSS under base flow and runoff conditions, whereas the other channelized reaches performed differently in different hydrological conditions. The high spatial and temporal variability of nutrients and TSS in the stream indicated that anthropogenic disturbance of the agricultural headwater stream, such as channelization and excavation, would be expected to decrease the capacity of nutrients retention in the stream.     

Advancing ion-exchange membranes to ion-selective membranes: principles,status, and opportunities

● IEM ion/ion selectivities of charge, valence, & specific ion are critically assessed. ● Ion/molecule selectivities of ion/solvent and ion/uncharged solute are reviewed. ● Approaches to advance the selectivities through sorption and migration are analyzed. ● The permeability-selectivity tradeoff appears to be pervasive. ● Ion/molecule selectivities are comparatively underdeveloped and poorly understood. Ion-exchange membranes (IEMs) are utilized in numerous established, emergent, and emerging applications for water, energy, and the environment. This article reviews the five different types of IEM selectivity, namely charge, valence, specific ion, ion/solvent, and ion/uncharged solute selectivities. Technological pathways to advance the selectivities through the sorption and migration mechanisms of transport in IEM are critically analyzed. Because of the underlying principles governing transport, efforts to enhance selectivity by tuning the membrane structural and chemical properties are almost always accompanied by a concomitant decline in permeability of the desired ion. Suppressing the undesired crossover of solvent and neutral species is crucial to realize the practical implementation of several technologies, including bioelectrochemical systems, hypersaline electrodialysis desalination, fuel cells, and redox flow batteries, but the ion/solvent and ion/uncharged solute selectivities are relatively understudied, compared to the ion/ion selectivities. Deepening fundamental understanding of the transport phenomena, specifically the factors underpinning structure-property-performance relationships, will be vital to guide the informed development of more selective IEMs. Innovations in material and membrane design offer opportunities to utilize ion discrimination mechanisms that are radically different from conventional IEMs and potentially depart from the putative permeability-selectivity tradeoff. Advancements in IEM selectivity can contribute to meeting the aqueous separation needs of water, energy, and environmental challenges.     

Factors affecting the distribution of microplastics in soils of China

● Microplastic (MP) abundance in soil of China was highly heterogeneous. ● MP abundance was higher near large rivers and central land affected by monsoons. ● MP abundance was correlated with longitude, mulching film, and average temperature. ● Factors suitable for predicting MP pollution using models were discussed. Microplastics (MPs) are found worldwide in high abundance, posing a potential threat to ecosystems. Despite the ubiquity of MPs in the environment, very little is known about the regional distribution of MPs and underlying factors affecting this distribution in the field, which likely include human activity, but also features of the environment itself. Here, out of a total of 1157 datapoints investigated in 53 Chinese studies, 9.68% datapoints were removed as outliers in the heterogeneity analysis. This review revealed that the abundance of MPs was highly heterogeneous. In addition, microplastic (MP) distribution maps based on China demonstrated that the highest abundance of MPs tended to occur near large rivers and central land affected by the intersection of two monsoons. The model-fitting and previous studies showed that MP abundance in China was correlated with longitude, agricultural mulching film usage per capita, temperature, and precipitation. However, due to the heterogeneity of MPs and the low matching degree between the current environmental data and the sampling points, this pattern was not as evident as reported in any single study. Factors affecting the distribution of MPs can not be captured by linear relationships alone, and systematic selection of suitable environmental factors and further model optimization are needed to explore the cause of MP pollution in soil. Overall, this review revealed an uneven distribution of MPs and serves as a reference for model prediction to assess and control plastic pollution in natural soil environments.     

珠江河口沉积物中拟除虫菊酯类农药污染及毒性评价

拟除虫菊酯农药是一种广谱、高效、低毒、低残留的亲脂性杀虫剂,它会随农田排水、降雨淋洗进入水体,最终进入沉积环境,故沉积物是其最终归宿之一。本研究针对珠江河口沉积物中菊酯类农药的污染状况进行调查,研究它们的含量、组成比例、污染来源及其潜在毒性,为珠江渔业水生生态环境管理及掌握环境中有机污染情况提供依据,对保护渔业环境安全有十分重要的意义。2012年5月采集珠江河口表层沉积物,采用气相色谱法-电子捕获法（GC-ECD）对表层沉积物中联苯菊酯、甲氰菊酯、高效氯氟氰菊酯、氯菊酯、氯氰菊酯、氰戊菊酯、溴氰菊酯进行残留检测,并利用其对钩虾的生物毒性来评价沉积物的潜在毒性。结果显示,表层沉积物（以干质量计）中7种菊酯类农药质量分数介于ND~6.59μg·kg-1（ND表示未检出）,平均值为0.75μg·kg-1,其总质量分数与有机碳质量分数呈现一定的正相关性;组成比例表明,氯菊酯最多,占总量的57.63%,它的检出率为61.90%,甲氰菊酯其次,约占总量的16.39%,检出率为28.57%,氯菊酯占主要组成部分,可能与其在珠江三角洲居民生活中被大量使用及其降解速率有关;珠江桥采样点高浓度的菊酯类农药的检出（6.59μg·kg-1）,可能与其靠近人口密集和经济发达的广州有关;与国内外其他地区相比,珠江河口沉积物中菊酯农药处于较低水平;采用毒性单元TU（选用钩虾Hyallela Azteca的LC50）进行毒性评估,∑TU值范围为0~0.09,远远低于1,表明珠江河口拟除虫菊酯不存在生态风险。     

基于GIS的上海浦东新区暴雨内涝灾害危险性分析

以上海市浦东新区为例,在修正已有的城市高程模型基础上,结合美国水土保持局SCS水文模型、降雨及排水因素,利用GIS栅格空间分析技术模拟了重现期5年、20年、50年、100年、200年、500年6种暴雨内涝灾害情景下的淹没深度和范围,并以街道(镇)为研究单元对上海浦东新区进行了暴雨内涝危险性评价。结果表明:5年一遇,全集中在0～0.2m;20年一遇,全集中在0～0.2m和0.2～0.6m;50年一遇和100年一遇,主要集中于0.2～0.6m,在此区间内淹没面积各占83.7%和70.8%;200年一遇和500年一遇,主要集中在大于0.6m的范围内,在此区间内淹没面积各占60.1%和66.5%。     

登陆台风低压再度发展引发的特大暴雨诊断分析

利用常规资料和NCEP1°×1°的分析场资料,对2008年8号台风"凤凰"减弱的低气压在滁河地区造成的特大暴雨灾害过程进行了较深入的分析。通过对暴雨期间涡度与垂直速度空间结构变化分析得到:暴雨的增幅发生在正涡度发展和上升运动明显增强的过程中,当上升运动开始减弱时,雨强也开始减小。     

洪水作用下村镇住宅的力学响应试验研究

针对洪水作用下村镇住宅的反应,通过建立房屋模型,研究不同洪水水力条件下,村镇住宅所受的洪水压力、应变等分布规律,并分析了不同房屋结构以及基础对抵抗洪水作用的影响,初步得到了洪水作用下村镇住宅的破坏机理。     

暴风雪作用下轻型钢结构房屋的损伤特征分析

基于雪灾事故的调查研究,对轻钢结构房屋在风荷载、雪荷载不同作用情况下的损伤特征及其结构受力性能进行了有限元分析。结果表明,风力涡旋效应造成屋面雪载的分布极不均匀,受损处常集中在屋面1/4和3/4跨附近;基本风、雪荷载值偏低以及轻型钢结构房屋的鲁棒性差,往往因局部损坏导致整体性坍塌。     

重庆市酸沉降污染经济损失估算

重庆市酸沉降降污染严重,为确定其造成的经济损失,经经济社会发展决策提供依据和拟订,选择满意的防治姑人群健康和农林污染危害调查,材料挂片耐蚀试验,模拟酸沉降实验等基础上,用人力资本法,市场价值法和投入产出损益比较法进行估算。