A HYDROCLIMATOLOGICAL ANALYSIS OF THE RED RWER OF THE NORTH SNOWMELT FLOOD CATASTROPHE OF 19971

ABSTRACT: The flood hydroclimatology of the Grand Forks flood of April 1997, the most costly flood on a per capita basis for a major metropolitan area in United States history, is analyzed in terms of the natural processes that control spring snowmelt flooding in the region. The geomorphological characteristics of the basin are reviewed, and an integrated assessment of the hydroclimatological conditions during the winter of 1996 to 1997 is presented to gain a real‐world understanding of the physical basis of this catastrophic flood event. The Grand Forks flood resulted from the principal flood‐producing factors occurring at either historic or extreme levels, or at levels conducive to severe flooding. Above normal fall precipitation increased the fall soil moisture storage and reduced the spring soil moisture storage potential. A concrete frost layer developed that effectively reduced the soil infiltration capacity to zero. Record snowfall totals and snow cover depths occurred across the basin because of the unusual persistence of a blocking high circulation pattern throughout the winter. A severe, late spring blizzard delayed the snowmelt season and replenished the snow cover to record levels for early April. This blizzard was followed by a sudden transition to an extreme late season thaw due to the abrupt breakdown of the blocking circulation pattern. The presence of river ice contributed to backwater effects and affected the timing of tributary inflows to the main stem of the Red River. Only the absence of spring rains prevented an even more catastrophic flood disaster from taking place. This paper contributes to our understanding of the flood hydroclimatology of catastrophic flood events in an unusual flood hazard region that possesses relatively flat terrain, a north‐flowing river, and an annual peak discharge time series dominated by spring snowmelt floods.     

Water Discoloration in Alexandria, Egypt, April 1993. I. Occurrence of Prorocentrum Triestinum Schiffer (Red Tide) Bloom and Associated Physical and Chemical Conditions

A yellow-brown coloration of water developed in the Eastern Harbour of Alexandria (Egypt) during April 1993. the dinoflagellate Prorocentrum triestinum, the causative organism, culminated in a population peak of 71-10⁶ cells 1^-1, chlorophyll a nearly 361 μgl^-1. the bloom occurred with a thermohaline stratified water column and low surface nutrient levels. Water temperature was considered a crucial environmental factor controlling the occurrence of P. triestinum and nitrate was significantly correlated with its counts. the high relative growth constant (3.4 d^-1), calculated just prior to the massive occurrence of the species, explains the rapid development of the bloom. A comparison with the earlier phytoplankton studies in the harbour is made.     

复合材料BiOI/BiOCl的制备及可见光催化降解活性艳红X-3B

以乙二醇为溶剂,利用溶剂热方法制备了不同I/Cl比的BiOI/BiOCl可见光催化材料.同时,采用X射线衍射光谱(XRD)、X射线光电子能谱(XPS)、紫外可见漫反射光谱(DRS)和光致荧光光谱(PL)对所制备材料的晶相、元素价态和光学性质等进行了表征,并以活性艳红X-3B为目标化合物,研究了不同I/Cl比对X-3B光催化降解动力学的影响.分析结果表明,BiOI和BiOCl能够得到很好的复合,在可见光范围内有很好的吸收.降解实验结果表明,I/Cl摩尔比为9∶1时,复合材料对X-3B的可见光降解效率最高,一级反应动力学速率为0.0133 min-1;TOC和COD在3 h内分别降低28%和25%左右,证明能够对所选目标染料在一定程度上实现矿化;在光催化降解活性艳红X-3B过程中起主要作用的为光生空穴.此外,还对复合材料光催化性能提高机理进行了探索与推测.     

我国赤泥环境管理现状分析

针对中国氧化铝行业日益严重的赤泥排放及堆存污染防治问题,本文简要介绍了国内赤泥产生、综合利用和堆存的环境管理现状,总结分析了目前赤泥环境管理存在的主要问题,进而提出了相应的对策建议。     

γ-Al2 O3 负载磷钨酸催化强化电化学法处理水中酸性大红3R的研究

采用浸渍法制备γ-Al2O3负载磷钨酸(HPW/γ-Al2O3)催化剂.运用红外光谱(FTIR)、X射线衍射(XRD)、热重-差热分析(TG-DTA)、扫描电镜(SEM)对催化剂的微观结构、形貌进行表征.结果表明杂多阴离子保持Keggin结构.将HPW/γ-Al2O3负载型催化剂填充于电化学反应器中,考察催化剂强化电化学法降解酸性大红3R染料的效果.研究表明,HPW/γ-Al2O3催化剂对酸性大红3R溶液显示了良好的催化活性,催化剂负载量为4.6%时,在pH为3、槽电压25.0 V、空气流速0.04 m3.h-1、极板间距3.0 cm反应条件下,60 min后,色度去除率达到97.6%.催化剂重复使用10次后,体系脱色率仍可达到80%左右,但会出现部分活性组分的流失现象.采用可见-紫外光谱对反应中间产物进行定性分析显示,在脱色反应过程中,染料分子中的共轭体系已基本被破坏.     

生态经济观是实现资源与环境良性循环的理论依据

本文根据资源与环境的对立统一规律,探讨了生态经济生产观、需求观和价值观的内容,从而揭示出生态经济观是实现资源与环境良性循环的理论依据。     

Stable-isotope probing of bacterial community for dissolved inorganic carbon utilization in Microcystis aeruginosa-dominated eutrophic water

Dissolved inorganic carbon (DIC) is an important source of carbon in aquatic ecosystems, especially under conditions of increased frequency of cyanobacterial bloom. However, the importance of bacteria in direct or indirect utilization of DIC has been widely overlooked in eutrophic freshwater. To identify the functional bacteria that can actively utilize DIC in eutrophic freshwater during cyanobacterial bloom, stable-isotope probing (SIP) experiments were conducted on eutrophic river water with or without inoculation with cyanobacteria (Microcystis aeruginosa). Our 16S rRNA sequencing results revealed the significance of Betaproteobacteria, with similar relative abundance as Alphaproteobacteria, in the active assimilation of H¹³CO₃^? into their DNA directly or indirectly, which include autotrophic genera Betaproteobacterial ammonia-oxidizing bacteria. Other bacterial groups containing autotrophic members, e.g. Planctomycetes and Nitrospira, also presented higher abundance among free-living bacteria in water without cyanobacteria. Microcystis aggregates showed a preference for some specific bacterial members that may utilize H¹³CO₃^? metabolized by Microcystis as organic matter, e.g. Bacteroidetes (Cytophagales, Sphingobacteriales), and microcystin-degrading bacteria Betaproteobacteria (Paucibacter/Burkholderiaceae). This study provides some valuable information regarding the functional bacteria that can actively utilize DIC in eutrophic freshwater.     

Profiles of and variations in aluminum species in PAC-MC used for the removal of blooming microalgae

Polyaluminum chloride modified clay (PAC-MC) is a safe and efficient red tide control agent that has been studied and applied worldwide. Although it is well known that the distribution of hydrolytic aluminum species in PAC affects its flocculation, little is known about the influence of particulars aluminum species on the microalgae removal efficiency of PAC-MC; this lack of knowledge creates a bottleneck in the development of more efficient MCs based on aluminum salts. The ferron method was used in this study to quantitatively analyze the distributions of and variations in different hydrolytic aluminum species during the process of microalgae removal by PAC-MC. The results showed that Al_a, which made up 5%–20% of the total aluminum, and Al_p, which made up 15%–55% of the total aluminum, significantly affected microalgae removal, with Pearson's correlation coefficients of 0.83 and 0.89, respectively. Most of the aluminum in the PAC-MC sank rapidly into the sediments, but the rate and velocity of settlement were affected by the dose of modified clay. The optimal dose of PAC-MC for precipitating microalgae was determined based on its aluminum profile. These results provide guidance for the precise application of PAC-MC in the control of harmful algal blooms.     

Identifying Anomalous Reports of Putatively Extinct Species and Why It Matters

Abstract:  As species become very rare and approach extinction, purported sightings can stir controversy, especially when scarce management resources are at stake. We used quantitative methods to identify reports that do not fit prior sighting patterns. We also examined the effects of including records that meet different evidentiary standards on quantitative extinction assessments for four charismatic bird species that might be extinct: Eskimo Curlew ( Numenius borealis ), Ivory-billed Woodpecker ( Campephilus principalis ), Nukupu`u ( Hemignathus lucidus ), and O`ahu `Alauahio ( Paroreomyza maculata ). For all four species the probability of there being a valid sighting today, given the past pattern of verified sightings, was estimated to be very low. The estimates of extinction dates and the chance of new sightings, however, differed considerably depending on the criteria used for data inclusion. When a historical sighting record lacked long periods without sightings, the likelihood of new sightings declined quickly with time since the last confirmed sighting. For species with this type of historical record, therefore, new reports should meet an especially high burden of proof to be acceptable. Such quantitative models could be incorporated into the International Union for Conservation of Nature's Red List criteria to set evidentiary standards required for unconfirmed sightings of "possibly extinct" species and to standardize extinction assessments across species.     

三十年来中国自然资源学会的发展与展望

中国自然资源学会迎来了30周年的大喜日子。论文系统地回顾了30 a来学会的发展历程,分析了存在的主要问题,对未来发展前景进行了展望。30 a来,学会经历了开创、发展和壮大的不同阶段,在为国家经济社会发展提供重要的资源科技支撑的同时,不断丰富资源科学研究的实践经验,并初步建立了中国特色的资源科学理论和方法体系框架。目前,学会已经拥有5 000多名会员、16个专业委员会、3个工作委员会、6个省级学会,成为中国科协下属的全国201个科技社团中的优秀学会之一。通过了国家民政部组织的中国社会组织评估并获得全国社会组织4A 级等级证书;获得了中国科协组织评审的优秀科技社团三等奖。但是,一些根本性问题仍然存在,包括:基本确立了资源科学但尚不牢靠;强调资源综合研究但分支学科分散;国内学术交流活跃但国际交流薄弱。未来学会将继续完善现有的理论方法体系,开拓资源学科研究的新领域;加强世界资源研究和国际合作交流;围绕国民经济应用性强的重大资源科学问题开展决策咨询;狠抓学科建设和资源科技人才培养;搭建"自然资源态势分析与学科发展信息平台"。