武汉月湖近代沉积物中的硅藻组合与环境关系研究

采集武汉月湖2处近代沉积物,分析了沉积硅藻组合与其环境关系,共发现24属83种硅藻。结果表明：2个柱状沉积物中硅藻优势属为小环藻属、直链藻属、舟形藻属、Cyclostephanos属。Z-1钻孔共有20属61种硅藻,Z-2钻孔共有24属68种硅藻。Z-1钻孔优势种为梅尼小环藻（Cyclotella meneghiniana）、颗粒直链藻（Aulacoseira granulata）、Navicula porifera、Cyclostephanos tholifomis。Z-2钻孔优势种为梅尼小环藻、颗粒直链藻、舟形藻（Navicula sp.）、Cyclostephanos invisitatus。就硅藻密度分布而言,总趋势上层最多,平均7.14×10^5～58.65×10^5 ind.g-1,中层其次,平均0.08×10^5～13.98×10^5 ind.g-1,下层最少,平均0.24×10^5～0.64×10^5 ind.g-1。硅藻种数最少的样品出现在沉积物中层,梅尼小环藻、颗粒直链藻、舟形藻、Navicula porifera、Cyclostephanos tholifomis、Cyclostephanos invisitatus的组合可以指示湖泊水体环境出现富营养化。通过探讨分析影响硅藻分布的环境因素,为恢复月湖近代水环境演化过程提供了依据。     

水生生物群落所揭示的湖泊水环境状况——以东平湖为例

东平湖作为国家南水北调工程东线的调蓄湖和山东省西水东送的水源地,在国家水资源配置战略中起着重要的作用.为了解其水生生物、水环境质量及湖泊富营养状态,在收集、整理和总结前人历年积累的东平湖水生生物等调查研究资料的基础上,并结合表层沉积硅藻和湖泊水质数据,分析东平湖目前的水环境状况及湖泊环境的潜在威胁.2011-2012年东平湖表层沉积物硅藻属种鉴定显示优势属为Aulacoseira、Synedra、Cyclotella、Navicula和Fragilaria,营养型属种居多,表明湖泊整体营养水平较高.由Shannon-Wiener多样性指数和Pielous种类均匀度指数分析得到东平湖硅藻门生物多样性指数为3.30和0.80,处于轻度污染水平.因此,由水生生物群落所揭示的东平湖环境状况为营养状态从富营养化转变为中营养-轻度富营养化状态,水体由中度污染转变为轻度污染甚至部分区域水体良好,整体处于Ⅲ类水标准.     

呼伦湖水体营养状态特征及其主要影响因子研究

呼伦湖地处中高纬度温带半干旱区,属于中温带大陆性草原气候,湖泊冰封期长达6个月,冰封期和非冰封期湖泊水体的营养状态具有显著的差异性。基于2015—2017年冰封期与非冰封期湖泊水质监测数据,采用综合营养状态指数法分析冰封期与非冰封期呼伦湖湖泊水体营养状态的变化特征,同时通过非线性概率Probit模型建立了呼伦湖富营养化影响因子模型并对湖泊水体富营养化主要影响因子讨论分析,研究结果表明呼伦湖总体上呈现轻度富营养化程度,2015—2017年呼伦湖冰封期内水体富营养化程度变化特征为2015—2017富营养化程度逐年增加,而非冰封期内水体富营养化程度的变化特征呈现2016年富营养化程度最大2017年最小,且冰封期内水体富营养状态程度较非冰封期严重;建立的呼伦湖富营养化影响因子的非线性概率Probit模型表明影响水体富营养化的主要水环境因子为总磷(TP)、pH值、盐度(S)、水深(H)、总氮(TN)及溶解氧(DO),其中总磷(TP)因子的响应概率为65.7%,对呼伦湖湖泊水体富营养化程度影响最大,说明磷是呼伦湖水体富营养化的重要限制因子,并且各主要水环境影响因子与综合营养状态指数间具有显著的相关关系,表明呼伦湖水体营养状态的改善可通过调节水体内各水环境因子维持相对平衡,同时加大对湖周围人类活动的管理,加强对禁牧的宣传来实现。     

武汉月湖水体营养物质的分布与硅藻的生态指示

通过对武汉月湖2007年1-12月水体理化指标(电导率、溶解氧、pH值、水温、透明度、无机氮、无机磷、可溶硅)、生物指标(硅藻、蓝藻、叶绿素a)的监测,结果表明:月湖水体中无机氮、无机磷含量较丰富,可溶硅含量较低;月湖水体初级生产力较高,湖泊中蓝藻密度远大于硅藻密度;月湖水体中浮游植物与生境因素有着复杂的生态网络关系.月湖水体营养盐结构不合理,在硅藻消亡后,湖泊水域中的营养组合(丰富的氮与磷,但缺乏可溶硅),这种特殊生境刺激蓝藻的生长,进一步导致硅藻的减少,使月湖浮游植物的优势种转变成蓝藻类.可溶硅在湖泊浮游植物群落由硅藻型向蓝藻演变的过程中起着重要的作用,可溶硅起始浓度水平不仅决定硅藻生产量最大值的程度,而且制约着硅藻持续时间,补偿湖泊可溶硅可能是防治湖泊富营养化的新路.     

利用多生物学指标评价宝应湖沉积物的环境质量

研究了江苏宝应湖沉积物浸出液对水生生态系统的生产者斜生栅列藻 (Scenedesmusobilquus)、初级消费者大型氵蚤 (Daphniamagna)和高级消费者斑马鱼 (Brachyddaniorerio)的影响。结果表明 ,沉积物浸出液对大型氵蚤和斑马鱼无明显的急性毒性。但与湖水对照相比 ,浸出液对斜生栅列藻的生长有显著促进作用 ,且随浸出液浓度升高 ,对藻类促进作用越大。化学监测结果表明 ,沉积物浸出液中磷浓度明显高于湖水 ,表明沉积物中磷向水体释放 ,可促进湖泊富营养化。     

不同实验规模下底栖藻垫的磷含量变化及其形态组成

底栖藻类的磷滞留作用是影响浅水富营养化湖泊磷循环的重要因素,为了探究浅水湖泊沿岸带不同规模围隔中底栖藻类滞留磷的潜力及磷的组成形态,应用连续提取法测定了东湖不同围隔及大湖水体(对照)中底栖藻垫的磷含量及其赋存形态.试验期间(一年),所有样点底栖藻垫的无机磷占总磷的百分比例(质量分数)均大于60%,是底栖藻垫中磷的主要存在形态;而无机磷主要由钙磷和铁/铝磷组成,其中围隔底栖藻垫的钙磷含量比对照高,但铁/铝磷含量低于对照.各样点藻垫有机磷占总磷的百分比例相对较低.各样点底栖藻垫的总磷浓度均在秋季达到最高,大于5 200μg/g(DW),不同季节之间没有显著差异,对照底栖藻垫的总磷浓度均值(4 983μg/g,DW)高于大、小围隔.综合分析表明,围隔中底栖藻垫滞留的磷及其赋存形态更有利于浅水高营养化湖泊沉水植物的恢复.     

长江中下游湖泊富营养化过程的湖泊沉积记录

长江中下游湖群区，历来是人类最活跃的场所，但由于近年来社会经济的迅速发展，湖泊富营养化问题日趋严重，对湖泊湿地变化与湖泊营养盐状况关系的分析是制定湖泊环境整治和生态修复的重要科学依据。长江中游湖泊——龙感湖的湖中心钻孔沉积物中硅藻组合和总磷变化记录了近百年来龙感湖富营养化过程。沉积物中湿地花粉与人湖营养盐关系以及磁化率的分析表明，流域内人类活动对湖周滩地的改造，破坏了湿地植被，助长了人湖物质的增加，湖泊营养相对富集，而流域农业化肥的使用导致了水质的进一步恶化。     

利用多生物学指标评价宝应湖沉积物的环境质量

研究了江苏宝应湖沉积物浸出液对水生生态系统的生产者斜生栅列藻（Scenedesmus obilquus)，初级消费者大型蚤（Daphnia magna)和高级消费者斑马鱼（Brachyddanio rerio)的影响，结果表明，沉积物浸出液对大型Sao和斑马鱼无明显的急性毒性，但与湖水对照相比，浸出液对斜生栅列藻的生长有显著促进作用，且随浸出液浓度升高，对藻类促进作用越大，化学监测结果表明，沉积物浸出液中磷浓度明显高于湖水，表明沉积物中磷向水体释放，可促进湖泊富营养化。     

新疆博斯腾湖表层沉积物中硅藻分布特征及影响因素分析

通过采集新疆博斯腾湖不同水深、矿化度、营养盐浓度及pH环境下的湖泊表层沉积物,提取硅藻并进行种属组合分析,研究了中国西北干旱区半封闭淡水湖泊中硅藻的分布特征,并且运用降维对应分析（DCA）,探讨了影响博斯腾湖现生硅藻组合特征的主要水质环境因子及硅藻种属对水体理化性质变化的响应。研究结果表明,在博斯腾湖硅藻组合受湖泊水深、矿化度影响明显分区：河口区受水体扰动作用影响明显,硅藻浓度变化大,以Fragilaria属为主;黄水湾区硅藻分布受矿化度及pH影响显著,以Mastogloia smithii、Navicula anglica、Gomphonema parvulum等底栖、喜碱性、微咸水种为主,淡水种Fragilaria属的含量明显低于其它区域,其含量的高低指示了水体矿化度的变化;在湖心区硅藻组合主要响应于水深变化,当水深增加时,Cyclotella radiosa、C.meneghiniana、Fragilaria bidens等浮游种含量显著增加,Mastogloria smithii、Gomphonema parvulum等底栖种含量明显降低或消失,且发现Fragilaria属在5.4～7.8m水深处生长繁盛。研究结果为建立中国西北干旱区的硅藻-环境因子关系数据库、重建本地区过去环境提供了理论依据。     

南亚热带城市浅水湖泊富营养化与浮游植物群落的时空特征：以肇庆星湖为例

星湖位于我国南亚热带地区,为城市浅水湖泊,由5个子湖(仙女湖、波海湖、青莲湖、中心湖和里湖)组成.于2002年的1月、3月、7月、8月、10B和12月对前4个子湖的水质和浮游植物进行了采样分析.星湖的总氮和总磷浓度分布范围分别为0.351～2.488 mg L-1和0.009～0.151 mg L-1,营养盐浓度变化规律均在3月达到最高值,7、8月逐渐降低,10、12月又有所增加.星湖的营养状态(TSI:40～56)整体处于中富营养化向富营养化过渡的阶段,各子湖营养状态存在一定的空间差异,波海湖富营养化程度最高,而仙女湖和青莲湖最低,这种空间差异主要由污染物的入湖位置和子湖的水动力连通特点所决定.从星湖共检到浮游植物128种,其丰度的分布范同为0.85×10644.28×106cells L-1.浮游植物3月丰度最低,7、8月最高.在数量组成上,4个子湖的浮游植物群落有很高相似性,群落结构以蓝藻-绿藻为优势类群.1月以绿藻和硅藻占优势,7、8、10和12月则由蓝藻占绝对优势,平列藻是最主要的优势种.浮游植物丰度的季节变化主要受季节性的降水和湖泊水位调节的影响.图2表6参30     

On the behaviour of the residence time at the bottom of the mixed layer

To understand why the findings of Deleersnijder et al. [(2006), Environ Fluid Mech 6: 25–42]—the residence time in the mixed layer in not necessarily zero at the pycnocline—are consistent with those of Delhez and Deleersnijder [(2006), Ocean Dyn 56:139–150]—the residence time in a control domain vanishes at the open boundaries of this control domain—, it is necessary to consider a control domain that includes part of the pycnocline, in which the eddy diffusivity is assumed to be zero. Then, depending on the behaviour of the eddy diffusivity near the bottom of the mixed layer, the residence time may be seen to exhibit a discontinuity at the interface between the mixed layer and the pycnocline. If such a discontinuity exists, the residence time is non-zero in the former and zero in the latter. This is illustrated by analytical solutions obtained under the assumption that the eddy diffusivity is constant in the mixed layer.     

豪猪消化系统的解剖研究

为了了解豪猪的消化生理,为豪猪的人工饲养技术研究提供基础依据,以达到高效饲养豪猪的目的,笔者对豪猪的消化器官进行了系统解剖研究.结果表明:豪猪的胃为单室胃.盲肠很发达,这与其能够消化植物纤维有关.豪猪肝脏很发达,其重量为402 g,是其体重的4.59%,肝脏分叶多而明显.     

Adjusting the economy to the new energy realities of the second half of the age of oil

Our research indicates that, due to the depletion of conventional, and hence cheap, crude oil supplies (i.e. peak oil), increasing the supply of oil in the future would require exploiting lower quality resources (i.e. expensive), and thus will most likely occur only at high prices. This situation creates a system of feedbacks where economic growth, which requires more oil, would require high oil prices that will undermine that economic growth. We conclude that the economic growth of the past 40 years is unlikely to continue unless there is some remarkable change in how we manage our economy.     

刍议医院资产管理的现状及其对策

医院的固定资产和流动资产是医院赖以生存和发展的基础,是一项非经营性国有资产．目前公立医院固定资产、流动资产管理现状不容乐观,针对这种状况,首先分析问题形成的原因,然后提出管理的措施或建议,从而使资产管理工作规范化、制度化、科学化,使有限的卫生资源发挥出最大的社会效益和经济效益．参3．     

Observations on the function of the glands of the foot of the pediveliger of Ostrea edulis during settlement

The use during settlement of secretions of the 9 different types of gland in the foot of the pediveliger of Ostrea edulis L. was examined experimentally. During settlement, there is a progressive decrease in the crawling speed of the larva and a strengthening of its bond with the substratum. Both changes are related to (a) a change from ciliary to muscular pedal locomotion; (b) the increasing acidity and viscosity of the mucoid secretions used; (c) the secretion of a byssus thread by the glands of the byssus duet; (d) changes in the form and composition of this byssus. At the termination of settlement, the entire contents of 2 types of gland are discharged. Their secretions give rise to the cement which permanently fixes the larva to the substratum. The 9 types of gland are utilised sequentially in a manner closely related to the 6 phases recognised in settlement behaviour.     

The impact of the Jonglei Canal on the economy of the local people

The idea of saving the water lost in the ‘Sudd’ swamp through evaporation was conceived by Egypt and Sudan for their own interests, but not for those of the Nilotic peoples living in the flood plain. Concern for the local development was only taken into consideration after the 1974 Juba riots, when three people were killed and 200 arrested. The canal has caused displacement of people from their settlements and is blocking the seasonal movement of livestock and wildlife. Conflict may arise over the use of land for grazing or irrigation. The Nilotics are concerned about the possible negative environmental impact, and the loss of their cultural identity. They maintain that Egypt should pay them monetary compensation for the disruption that the canal has caused to their livelihood.

This paper assesses the impact that the Jonglei canal project will have on the economy of the Nilotics; traces the historical development of the project; outlines the social, political and economic organization of the Nilotics; and assesses the impact the project will have on the local population. The paper concludes by casting doubt on the benefits the canal will bring to the Nilotics.     

Mining of the forest and the time path of the price of timber

The paper analyzes the effect of transportation (site specific) costs and the effect of mining (depletion) of the forest on the time path of the price and of the net price of timber in two forestry models. The models differ in that one has zero costs and the other has positive costs. The analyses yield the standard mining theory results for certain cases. They also yield extentions of these results for cases with growth of the harvested trees and/or regeneration on the harvested land. The paper concludes, as one would expect, that the theory of the mine is useful in analyzing the time path of the price of timber.     

三峡库区消落带土壤中铅污染调查

报道了三峡库区长江干流及小江支流消落带土壤中重金属铅含量背景值的调查结果。结果表明，目前土壤未被重金属铅污染。     

浅谈校园网ARP欺骗攻击与防御

ARP欺骗木马病毒是校园网络中经常出现的病毒攻击形式．基于ARP协议的概念和工作原理,并通过分析ARP欺骗的工作原理,提出了几种可行的解决ARP欺骗攻击的实用方法,以达到防范并解决ARP欺骗的目的．参5．