The fluid mechanics of arthropod sniffing in turbulent odor plumes

Many arthropods capture odorant molecules from the environment using antennae or antennules bearing arrays of chemosensory hairs. The penetration of odorant-carrying water or air into the spaces between these chemosensory hairs depends on the speed at which they are moved through the surrounding fluid. Therefore, antennule flicking by crustaceans and wing fanning by insects can have a profound impact on the odorant encounter rates of the chemosensory sensilla they bear; flicking and fanning are examples of sniffing. Odors are dispersed in the environment by turbulent wind or water currents. On the scale of an antenna or antennule, an odor plume is not a diffuse cloud but rather is a series of fine filaments of scent swirling in odor-free water. The spatiotemporal pattern of these filaments depends on distance from the odor source. The physical interaction of a hair-bearing arthropod antennule with the surrounding fluid affects the temporal patterns of odor concentration an animal intercepts when it sniffs in a turbulent odor plume.     

从源头防治制浆造纸废水污染的新策略

制浆造纸工业废水对环境造成了严重污染。本文概述了微生物生物技术在防治造纸污染中的应用,同时着重介绍了木质素生物合成途径与转基因植物降低造纸原料木质素含量的研究进展,对我国发展从源头防治制浆造纸污染的策略提出了建议     

农业面源污染管理政策调控仿真模型研究进展

农业面源污染因其分散性、滞后性和不确定性而成为环境治理的难点。面源污染物迁移转化过程的模拟模型发展迅速,而农业面源污染管理政策仿真评估模型研究相对较为滞后。系统梳理与分析了自上而下宏观目标约束、自下而上微观行为传导及宏观与微观上下耦合三类政策仿真模型研究进展,总结了当前模型的基础理论与方法的优势与不足。本文提出了融合流域水系统过程规律认知,构建宏观政策目标自上而下约束与微观主体行为自下而上传导耦合的农业面源污染政策仿真模型,实现政策仿真模拟在国家、区域、流域与栅格跨尺度上的嵌套传导、参数互验与系统预测,以解决因农业面源污染防治主体的多元性与防治对象的广泛性特征所导致的复杂性系统难题,使得政策效应模拟仿真结果空间显性化,进而实现农业面源污染控制的政策管理由粗放型向精准化方向迈进。     

Internal model sliding mode control approach for glucose regulation in type 1 diabetes

Patients with type 1 diabetes require insulin therapy to maintain blood glucose levels within safe ranges since their pancreas is unable to complete its function. The development of a closed-loop artificial pancreas capable of maintaining normoglycemia during daily life will dramatically improve the quality of life for insulin-dependent diabetic patients. In this work, a closed-loop control strategy for blood glucose level regulation in type 1 diabetic patients is presented. A robust controller is designed using a combination of internal model and sliding mode control techniques. Also, the controller is provided with a feedforward loop to improve meal compensation. A simulation environment designed for testing the artificial pancreas control algorithms has been used to evaluate the controller. The simulation results show a good controller performance in fasting conditions and meal disturbance rejection, and robustness against model–patient mismatch and meal estimation errors.     

中国农业生态效率评价方法与实证——基于非期望产出的SBM模型分析

生态效率是衡量经济与资源环境协调发展的重要指标.基于将农业面源污染作为非期望产出的考量,在对传统DEA模型进行修正的基础上,采用非径向、非角度的SBM模型对中国30个省份的农业生态效率进行了测算,并给出了农业生态效率的改善途径.研究结果表明:1998-2009年中国农业生态效率虽然呈现缓慢上升态势,但整体仍处于较低水平,除北京、上海、海南、重庆外,其余省市都需要改变投入和产出来优化农业生态效率;资源的过度消耗和环境污染物的过量排放是农业生态效率损失的主要原因.提高资源利用效率、降低资源消耗量和环境污染物的排放量是农业生态效率改善的重要途径.     

海河流域面源污染风险格局识别与模拟优化

面源污染是海河流域面临的主要水生态环境问题,如何通过流域景观格局优化实现对面源污染的控制一直是研究的热点问题。通过最小累积阻力模型,以海河流域为研究对象,将流域景观要素及影响流域景观过程的外部因子相结合,对海河流域面源污染风险格局进行了识别,并将阻力格局与海河流域实测水环境指标进行相关性分析及验证,在此基础上对流域污染风险进行识别与优化模拟。结果表明海河流域有40%以上(130380 km2)区域面临高污染风险,集中分布在中南部平原地区以及山区河谷地带;对此设置河流植被缓冲带进行格局优化模拟分析,通过比较不同措施格局优化阻力值变化趋势表明,对于二级河流水系,加强河流两岸600—1600 m范围的人类活动管控,可以有效降低污染物输出,显著降低流域面源污染发生的风险。在面源污染风险等级较高的平原地区,设置300—400 m植被缓冲带,可将风险等级降低50%,设置700—800 m岸边植被缓冲带即可达到最佳效果;而在山区地区因风险较低,设置400—500 m的植被缓冲带即可达到最佳效果,能够将污染风险在现有基础上降低30%—40%。这一研究结果对海河流域景观格局优化和面源污染风险控制提供科学参考。     

Geographical variation in ribotype profiles of Escherichia coli isolates from humans,swine, poultry,beef, and dairy cattle in Florida

Waters impacted by fecal pollution can exact high risks to human health and can result in financial losses due to closures of water systems used for recreation and for harvesting seafood. Identifying the sources of fecal pollution in water is paramount in assessing the potential human health risks involved as well as in assessing necessary remedial action. Recently, various researchers have used the ribotyping method to identify sources of bacterial indicators (Escherichia coli and enterococci) in environmental waters. While these studies have identified genotypic differences between human- and animal-derived indicators that are capable of differentiating organisms isolated from humans and various animal hosts, most have focused on organisms collected from a confined geographic area and have not addressed the question of whether these ribotype profiles are watershed specific or if they can be applied universally to organisms from other geographic locations. In this study, E. coli isolates were obtained from humans, beef cattle, dairy cattle, swine, and poultry from locations in northern, central, and southern Florida and were subjected to ribotyping analysis. The intent was to determine (i) if ribotype profiles are capable of discriminating the source of E. coli at the host species level and (ii) if the resulting fingerprints are uniform over an extended geographic area or if they can be applied only to a specific watershed. Our research indicated that, using a single restriction enzyme (HindIII), the ribotyping procedure is not capable of differentiating E. coli isolates from the different animal species sampled in this study. Results indicate, however, that this procedure can still be used effectively to differentiate E. coli as being either human or animal derived when applied to organisms isolated from a large geographic region.     

Distribution of bacteria with nitrilotriacetate-degrading potential in an estuarine environment.

Attempts to isolate estaurine bacteria capable of metabolizing nitrilotriacetate (NTA) as a sole carbon source from areas within Escambia Bay, Fla., were unsuccessful; however, bacteria from freshwater streams and from estaurine surface microlayers were easily adapted to degradation of NTA in freshwater medium. A Pseudomonas sp. strain (ATCC 29600), capable of growth on NTA as a sole carbon source, metabolized NTA at a reduced rate in a saline medium (15%), compared with a freshwater medium (0 to 15%). Microorganisms capable of degrading NTA exist in estuarine surface microlayers and in fresh subsurface waters just before entering the estuary; these data indicate an interference with NTA catabolism by some unknown factors of the estuarine environment rather than an absence of potential NTA-degrading bacteria.     

Molecular characterization of sulfate-reducing bacteria in anaerobic hydrocarbon-degrading consortia and pure cultures using the dissimilatory sulfite reductase (dsrAB) genes

The characterization of sulfate-reducing bacteria (SRBs) is presented using the dissimilatory sulfite reductase (dsrAB) gene from various samples capable of mineralizing petroleum components. These samples include several novel, sulfidogenic pure cultures which degrade alkanes, toluene, and tribromophenol. Additionally, we have sulfidogenic consortia which re-mineralize benzene, naphthalene, 2-methylnaphthalene, and phenanthrene as a sole carbon source. In this study, 22 new dsrAB genes were cloned and sequenced. The dsrAB genes from our pollutant-degrading cultures or consortia were distributed among known SRBs and previously described dsrAB environmental clones, suggesting that many biodegradative SRBs are phylogenetically distinct and geographically wide spread. Specifically, the same dsrAB gene was discovered in independently established consortia capable of benzene, phenanthrene, and methylnaphthalene degradation, indicating that this particular SRB may be a key player in anaerobic degradation of hydrocarbons in the environment.     

Application of PFGE to source tracking of faecal pollution in coastal recreation area: a case study in Aoshima Beach, Japan

Aims: The development of a microbial source tracking (MST) method is strongly desired to ensure public health and bacteriological safety in coastal recreation areas. We try to specify the source of faecal pollution by applying pulsed‐field gel electrophoresis (PFGE) to the study of the aquatic environment on Aoshima Beach, Japan. Methods and Results: Enterococcus faecium, an enterococcus, was used as a faecal indicator bacterium in this study. Enterococcus faecium strains were isolated and identified from each water sample collected from Aoshima Beach and five rivers (Oyodo, Kiyotake, Kaeda, Chifuku and Tsukunami Rivers) that might be potential sources of faecal pollution. Enterococcus faecium strains collected from water samples were analysed using PFGE. The similarities of all the PFGE types of the Ent. faecium strains were compared using dendrogram analysis. The PFGE types of the strains isolated from Aoshima Beach showed a high similarity to those of the strains isolated from the Oyodo River at a 0·9 similarity level. It was suggested that the Oyodo River is the source of faecal pollution on Aoshima Beach. Conclusions: The PFGE analysis using enterococci is a potential tool for the MST of faecal indicator bacteria that can be applied to the study of the coastal environment. Significance and Impact of the Study: This is one of the studies that PFGE was applied to the coastal environment. The approach using PFGE could estimate the river that is source of faecal pollution in Aoshima Beach. By applying PFGE as a tool of MST method, detailed information of faecal pollution in coastal area can be provided.     

半干旱半湿润地区流域非点源污染负荷模型研究进展

受特殊的地理环境和气候条件影响,半干旱半湿润地区具有较复杂的水文循环过程及非点源污染发生和迁移转化机制。流域非点源污染负荷模型是定量化描述流域系统复杂水文循环及污染物迁移转化过程的有效手段,也是流域生态系统管理的重要工具。本文从半干旱半湿润地区特殊的气候、水文特征及下垫面情况出发,详细阐述了非点源污染的发生机理,系统总结了流域非点源污染负荷模型在解决水环境重要问题中研究与应用的现状、进展与不足,提出了适用于半干旱半湿润地区的非点源污染负荷模型的构建思路,并展望了流域非点源污染负荷模型的发展趋势。     

高效石油降解菌群的构建及对芳香烃化合物萘的协同降解性能

【背景】石油作为一类混杂有机化合物,一旦产生污染就会对人类和环境造成严重的危害。【目的】从新疆石油污染土壤中分离筛选石油降解菌,为石油污染土壤的生物修复提供数据支持及技术参考。【方法】以石油为唯一碳源,通过富集培养、筛选分离得到123株单菌,根据菌落形态挑选出30个不同形态菌株,通过16S rRNA基因序列确定其种属,构建系统发育树;通过原油降解实验筛选出高效石油降解菌,以芳香烃的标志化合物萘为唯一碳源筛选出高效降解菌株,并分别筛选可降解水杨酸、邻苯二酚的菌株。【结果】分离筛选出5株高效石油降解菌,降解率高于85%;萘、水杨酸和邻苯二酚降解菌株各获得一株,将3种菌株按照1:1:1的接种比例对萘进行降解,萘的降解率从单菌60.74%提升到89.40%,菌株间的分工协作可以提高有机物的降解效率。【结论】筛选得到的菌株丰富了石油降解微生物菌种库,不同微生物菌株之间的分工协作为石油污染物的降解提供了新思路,为进一步研究石油污染治理提供参考。     

基于径流路径的分布式面源污染模型研发与应用进展

精准刻画地表径流的路径及其所携带的面源污染物随径流的输移过程是准确估算面源污染入水体量、污染关键源区辨识和高效防控的关键,在我国以小农户种植为主、景观特征复杂的地理条件下尤为重要。鉴于目前常用的面源污染模型大都起源于国外,往往对径流路径的空间差异性及污染物陆面输移过程进行概化,介绍了一个基于径流路径的分布式面源污染模型(STEM-NPS)及其研发与应用进展。阐述了该模型的研发背景、模型原理和结构,说明了STEM-NPS模型对地表径流汇流及其所携带的污染物输移过程的精细化表达方法;介绍了该模型在不同地理环境及尺度的应用进展,展示了其在地块尺度的面源污染关键源区辨识,关键过程和关键影响因素解析及面源污染监管决策支持等方面的功能;探讨了STEM-NPS模型与其他常用模型的异同,并结合生态学研究和面源污染精准防控的需求,提出模型的应用前景及进一步发展的方向。     

Bacteriological aspects of pollution in the Jukskei — Crocodile river system in the Transvaal,South Africa

A combination of routine methods of bacteriological analysis has been utilised to investigate conditions in a river system which in part is subject to the effects of the discharge of appreciable quantities of sewage effluents which, during the dry season, may constitute the major part of the total flow. Other parts of the river system are free from gross pollution, and results obtained from these sections served as a basis for comparison. The river system is capable of coping with most of the detrimental effects of direct faecal pollution in varying form. But under no circumstances do these findings imply that the river system is capable of dealing with unrestricted quantities of sewage effluents for an unlimited period of time. Industrial pollution of varying character has been found to have little, if any, effect on bacterial numbers. The effect these effluents may have on the composition of the bacterial population as a whole has not been investigated, but this influence would be of local significance only. The methods used and the interpretations applied to the results seem to constitute a valuable instrument in the detailed study and assessment of bacteriological quality of the waters in a natural river system which is subject to severe pollution from sewage and industrial effluents of varying character.     

Geographical Variation in Ribotype Profiles of Escherichia coli Isolates from Humans, Swine, Poultry, Beef, and Dairy Cattle in Florida

Waters impacted by fecal pollution can exact high risks to human health and can result in financial losses due to closures of water systems used for recreation and for harvesting seafood. Identifying the sources of fecal pollution in water is paramount in assessing the potential human health risks involved as well as in assessing necessary remedial action. Recently, various researchers have used the ribotyping method to identify sources of bacterial indicators (Escherichia coli and enterococci) in environmental waters. While these studies have identified genotypic differences between human- and animal-derived indicators that are capable of differentiating organisms isolated from humans and various animal hosts, most have focused on organisms collected from a confined geographic area and have not addressed the question of whether these ribotype profiles are watershed specific or if they can be applied universally to organisms from other geographic locations. In this study, E. coli isolates were obtained from humans, beef cattle, dairy cattle, swine, and poultry from locations in northern, central, and southern Florida and were subjected to ribotyping analysis. The intent was to determine (i) if ribotype profiles are capable of discriminating the source of E. coli at the host species level and (ii) if the resulting fingerprints are uniform over an extended geographic area or if they can be applied only to a specific watershed. Our research indicated that, using a single restriction enzyme (HindIII), the ribotyping procedure is not capable of differentiating E. coli isolates from the different animal species sampled in this study. Results indicate, however, that this procedure can still be used effectively to differentiate E. coli as being either human or animal derived when applied to organisms isolated from a large geographic region.     

基于“源-汇”景观的典型半城市化小流域非点源污染风险评价

小流域的水质恶化主要由点源污染和非点源污染引起,随着点源污染控制水平达到一定程度后,非点源污染已成为首要污染源。当前对非点源污染的管控仍存在难监测和难治理的问题,明晰非点源污染发生风险以及背后的原因是亟需解决的问题,因此开展非点源污染风险分析和评价具有重要意义。采用高分辨率影像解译了2010年、2015年和2020年三期厦门市后溪流域土地利用数据;基于"源-汇"景观格局方法计算研究区网格单元的网格污染指数（GPI）;结合土地利用变化数据分析非点源污染风险的时空变异,对风险区成因进行了分析。研究结果表明：当前,"汇"景观占流域面积的67.86%,非点源污染发生风险分布呈现北低南高;十年中,非点源污染风险呈现上升趋势,目前非点源污染发生风险处于低风险水平（GPI=0.27）。通过分析风险区的土地利用构成发现耕地面积的缩减（减少67.08%）和建设用地面积扩张（增加43.02%）是污染风险发生变动的主要原因。计算了风险区转移矩阵,发现非点源污染发生风险区呈现出中高风险区向低风险区和"汇"景观区域转移的趋势。基于"源-汇"景观格局理论计算的网格污染指数（GPI）可以有效地对流域非点源污染风险值进行表征,是评价和分析流域非点源污染发生风险的可用方法。     

Anaerobes in waters

The classification of anaerobic bacteria in the aquatic environment with regard to their ability to survive in extreme environments (such as high or low temperatures, high salinity and pH) as well as the pathogenicity of Clostridia are presented briefly in this article. The importance of anaerobic bacteria in environmental pollution and several types of corrosion is discussed. The usefulness of anaerobic bacteria as pollution indicators of pollution in the aquatic environment and the methods used for their isolation, enumeration and identification are also presented.     

基于“源-汇”景观的饮用水源地非点源污染风险遥感识别与评价

非点源污染因分布广泛、产生过程复杂、防治困难,近年成为影响饮用水源地水环境的重要污染源。以海南三亚赤田水库为例,开展了基于"源-汇"景观的非点源污染风险遥感识别与评价分析。首先,采用高分辨率遥感影像分类提取水源地不同类型景观分布信息;结合"源-汇"对污染的促进\\阻碍作用,在考虑影响污染物迁移的"河道距离"因子、坡度因子情况下,利用非点源污染风险指数的计算实现对区域非点源污染风险的快速识别;并基于洛伦兹曲线分析水源地景观空间分布对非点源污染的影响。结果表明:一方面,流域非点源污染风险总体较低,"汇"景观占主导作用的子流域占整个区域的76.50%;污染风险呈现东高西低的特点,极高风险区主要分布于以居住用地、建设用地等"源"景观类型为主的流域东南部区域,占整体区域面积的1.28%,而西部以林地为主污染风险小;另一方面,基于坡度因子的"源""汇"景观污染负荷之比值大于1,"源"景观在低坡度区域分布范围广,景观布局较合理;基于"河道距离"因子的"源""汇"景观污染负荷之比值为2.30,"源"景观在距河道近的区域分布范围大,对污染影响大,近河道区域需进一步调整景观格局以降低对非点源污染的影响。基于遥感与"源-汇"景观指数计算是一种快速、客观、有效的饮用水源地的非点源污染风险识别与评价方法。     

我国城市地表径流污染治理技术探讨

城市地表径流是典型的非点源污染,具有地域范围广、随机性强、成因复杂等特点,已成为水环境污染的重要因素之一。本文提出由源处理、输移控制和汇处理组成的城市地表径流污染控制对策,并探讨了各种具体的城市径流污染控制与治理技术,认为初期雨水的有效截留将成为下一步的研究重点。