琵琶湖中浊度的季节变化

Seasonal variation of the turbidity (suspended substance) has been investigated in Lake Biwa. During the last five years, vertical and horizontal distributions of water temperature, turbidity, electric conductivity and chlorophyll-a have been obtained both in the south basin and the southern part of the north basin of Lake Biwa. The benthic nepheloid layer (BNL) developed in the seasons of thermal stratification, and is not detectable in the non-stratification period (winter). The BNL is mainly maintained by the organic matter such as phytoplankton under decomposition. However, the turbidity in the nepheloid layer was much affected by the turbid water from rivers after heavy rainfall. In this case, the major component of the suspended substance (SS) in the nepheloid layer was inorganic soil. The particulate P concentration, which is originated from phytoplankton, also increased after a rain fall. This suggests that phytoplankton in the surface layer sinks with clay and silt coming through rivers. From summer to the end of the stratification period, another kind of turbidity appeared in the bottom layer. This is caused by the chemical reaction of manganese under the anoxic condition. The resuspension of bottom sediment by strong currents also occurred, but it is not a major process for maintaining the BNL.     

太湖微囊藻的生长动力学

Following the development of local industries, agriculture and the increase of living standard of people, Lake Taihu is in the meso-eutrophication stage. The main eutrophication part in this lake is the Meiling Bay. The dominant phytoplankton species are Microcystis, Anabena, Melosira, Cyclotella and Cryptomonas. In summer, Microcystis spp. occupys 85% of algae biomass and form the water bloom. This causes the trouble for the people lived around the lake, especially for the drinking water of Wuxi City.The Microcystis intrinsic rate was high, the Max. growth rate 1.27. Besides Microcystis own characteristics, its growth depended on irradiation, temperature and nutrients, especially the phosphorus. This paper also discussed the possibility of biomanipulation for restoration of lake ecology and the control strategy of lake eutrophication.     

后生浮游动物摄食对太湖夏季微囊藻水华形成的作用

为了了解后生浮游动物的摄食作用在太湖夏季微囊藻水华形成中的作用,2009年7月15日至8月14日取太湖梅梁湾湖水开展了后生浮游动物对微囊藻水华形成作用的野外模拟实验.实验期间,未过滤掉后生浮游动物的对照组出现了漂浮在水面、肉眼可见的微囊藻水华,而过滤掉后生浮游动物的实验组没有出现微囊藻水华.结果显示,对照组整个实验期间都有后生浮游动物存在,共发现了9种后生浮游动物;而实验组在实验第6 d发现有后生浮游动物出现,整个实验期间共发现了3种后生浮游动物.浮游动物生物多样性分析显示对照组显著高于实验组.实验后期(21～30 d),对照组微囊藻平均密度显著高于实验组.整个实验期间,惠氏微囊藻(Microcystis wesenbergii)和水华微囊藻(Microcystis flos-aquae)密度均显著高于实验组,且惠氏微囊藻密度占对照组微囊藻总密度的60.79%.研究结果表明,太湖夏季后生浮游动物摄食并不能控制太湖蓝藻水华,相反,后生浮游动物特别是大型浮游动物能促进蓝藻水华的形成.同时表明,后生浮游动物群落结构可能是影响微囊藻水华形成的重要因素.     

武汉东湖微囊藻水华形成及消失原因的探讨——围圈放养实验

采用围圈试验的方法,将东湖微囊藻水华的形成和消失过程重现。根据有关生物调控(Biomanipulation)的原理,我们设计了鲢鳙草鱼的放养试验。实验结果表明:放养鲢鳙的围圈,水华在很短时间(约15天)内消失,放养草鱼的围圈,水华几乎不受影响,而没有放养的围圈,其水华日趋浓厚。这一结果显示出滤食性鱼类对围圈内浮游生物群落结构的影响是巨大的。在实验过程中通过测定碳、氮、磷等营养元素的变化,重点探讨了它们对微囊藻水华形成与消失过程的影响。     

微囊藻水华附生菌的代谢特征及对微囊藻生长的影响

为研究附生细菌对蓝藻水华细胞微环境的影响,从微囊藻水华中分离出34株藻附生细菌,研究其产酶能力.对氮代谢相关的酶活性测定结果显示:其中13株菌具有蛋白酶活性,5株菌具有较强的氨氮脱除能力,1株菌具有强烈的硝酸还原酶活性;4株菌具有较高的碱性磷酸酶活性;11株菌具有产脂酶的活性.通过菌和藻共同培养的方法,观察菌对微囊藻生长的影响,结果显示,有11株菌表现出较明显的促藻生长作用,占总筛选菌株总数的32%;有3株菌表现出较显著的抑制藻生长的作用,占总筛选菌株总数的9.9%.附生菌产酶能力与生长相关性的分析显示,促进微囊藻生长的附生菌都具有蛋白酶或脂酶活性.     

滇池微囊藻水华多糖的提取和化学特征

为了研究"水华"微囊藻多糖及其对水体化学和生态特性的影响,以去离子水、pH5的缓冲液和pH9.2的缓冲液为提取液,分别在4℃和80℃条件下从滇池"水华"微囊藻中提取多糖,并对其所提多糖部分化学特征进行分析.结果表明pH9.2的缓冲液所提多糖总得率最高,为2.25%;pH5的磷酸盐缓冲液所提多糖总得率最低,为0.383%.溶解性分析表明,不同提取液所提多糖在所试验的几种溶剂中表现为不溶、分散或部分溶解,未能找到将多糖完全溶解的溶剂.气相色谱和气-质联用分析表明,不同提取液所提多糖都含有中性单糖鼠李糖、阿拉伯糖、甘露糖、葡萄糖、半乳糖和一个未知糖.硫酸-咔唑法分析显示不同提取液所提多糖含有糖醛酸.电感耦合等离子光谱显示去离子水4℃条件下所提多糖含有很高的金属元素钙和镁,分别为2.15%和0.4%.初步研究显示,"水华"微囊藻多糖为酸性杂多糖,低溶解性显示在自然水体中它易形成多糖颗粒,有较高含量的金属元素说明它会影响到这些金属元素在滇池中的溶解、沉积、生物利用和循环,特别是钙和镁.     

太湖梅梁湾水华微囊藻基因型组成和产毒微囊藻丰度的变化

采用基于ITS序列的PCR-DGGE方法分析了太湖梅粱湾水华暴发过程中(6-11月)微囊藻的不同基因型组成的变化,同时利用针对微囊藻毒素合成酶基因mcyA和微囊藻特异性的16S rDNA部分核苷酸序列的引物,应用实时荧光定量PCR方法(qRT-PCR)分析水华样品中产毒微囊藻与总微囊藻的量.通过两者的比值反映产毒微囊藻丰度.结果表明,在发生水华的不同时期,微囊藻的基因型组成发生了变化,其中以8月末、9月和10月的基因型最多,基因型M5和M10存在于整个水华发展过程中.共检测到12种主要的基因型,每个基因型在水华的不同时期所占的比例互不相同.实时荧光定量PCR结果显示从6月到10月,产毒微囊藻的丰度呈增大的趋势,从0.750%增加到32.16%,而11月产毒微囊藻的丰度显著下降.     

水华微囊藻(Microcystis flos-aquae)生长周期中腐殖酸的释放特性

由于严重的水体富营养化,太湖长期暴发蓝藻水华,这些蓝藻在代谢及消亡过程中大量释放包括腐植酸在内的有机物,不仅影响供水水质,并且进一步加重了水华程度.以太湖水华优势藻种——水华微囊藻(Microcystis flos-aquae T34)为研究对象,对藻株生长周期中的藻细胞、浮游细菌进行计数,并使用TOC仪与三维荧光光谱对培养液中提取的腐殖酸进行定量与定性分析,探究水华微囊藻在生长过程中藻细胞密度、浮游细菌密度与腐殖酸浓度的变化规律.结果表明,培养液中腐殖酸浓度的变化趋势与细菌数量变化趋势一致,但与细菌数量曲线拐点相比,腐殖酸浓度曲线拐点出现两周的延迟.腐殖酸产量在藻细胞对数期较低,当水华微囊藻进入稳定期与衰亡期后,腐殖酸大量产生,其浓度迅速增加,最高可达到28.6 mg/L.根据三维荧光光谱分析,水华微囊藻所产生的腐殖酸特征峰出现在(235~245 nm)/(380~425 nm),属于类富里酸荧光峰.本研究初步探究蓝藻与水体腐殖酸之间的关系,为水体腐殖酸来源的研究提供了新的思路.     

细菌群落组成对微囊藻水华分解过程的响应

为探究细菌群落组成对微囊藻水华腐败分解过程的响应,在太湖梅梁湾沿岸进行为期11 d的原位围隔实验,模拟蓝藻水华聚集分解过程,并监测了此过程中水体环境因子和细菌群落组成.结果表明,水体理化因子和细菌群落组成在微囊藻水华分解的过程中发生了显著变化.冗余分析显示细菌的群落组成与水体氧化还原环境(溶解氧或氧化还原电位)、pH值、浮游植物生物量和营养盐浓度(总磷、硝态氮浓度)密切相关.研究还发现了某些与微囊藻水华分解密切相关的特殊细菌类群,其中隶属于黄杆菌科(拟杆菌门)的一个类群在微囊藻厌氧分解的阶段占据显著优势,其功能有待于进一步研究.     

水华衰亡过程中微囊藻群体胶鞘结构及其元素组成的变化

维系微囊藻群体结构的胶鞘是微囊藻水华维持优势的重要原因之一.为了探讨微囊藻水华的衰亡机理,在太湖梅梁湾水华衰亡过程中(10月至次年1月),对微囊藻群体大小的组成做了统计,同时对单位藻细胞的胶鞘多糖产量变化进行了检测,并对微囊藻群体胶鞘的变化进行了能谱扫描电镜观察和元素组成分析.结果表明,随着水华的衰亡,100~180μm的微囊藻小群体的比例表现出增多的趋势,而大于180μm的大群体逐渐减少,单位藻细胞的多糖含量呈现下降的趋势.扫描电镜结果显示了微囊藻群体的胶鞘从完整到逐渐裂解的变化过程,群体表面的能谱化学元素分析显示,钠和磷元素的百分含量呈下降的趋势,铝和硫元素的百分含量趋于稳定,而钙和硅元素的百分含量呈上升的趋势.以上结果说明了微囊藻群体中单位细胞的多糖产量减少,群体胶鞘裂解,元素组成发生变化,伴随着微囊藻群体的解聚,出现水华的衰亡.     

日本琵琶湖流域大气边界层的三维数值模拟

本文在地形坐标下引入一种水平导数差分近似方法,建立一个适合日本琵琶湖复杂地形、满足静力平衡条件的三维非定常大气边界层数值模式。在弱的背景风场下,模式加入了琵琶湖流域的实际地形,计算结果表明:模式运行十分稳定,且占机内存小,节省计算时间,同时模式还做了流域地形、湖泊本身存在与否等因子对边界层风场影响的数值试验。在强的背景风场下,模式加入了经过适当平滑的琵琶湖流域地形,得出了一些有益的看法。     

太湖、琵琶湖中水平扩散系数的探讨

根据１９９２年和１９９３年在太湖和日本琵琶湖观测到的长序列湖流资料,依据Ｔａｙｌｏｒ扩散理论计算了太湖和琵琶湖中的水平扩散系数,计算结果与通过浓度扩散方程计算基本一致。     

一个三维斜压水动力模型的建立及其在日本琵琶湖中的应用

水温的空间分布对很多湖泊水文现象关系甚大,本文建立了日本琵琶湖的三维斜压水动力数值模式。模拟计算结果表明：１）在不同风速驱动下,湖的上、下两层可形成不同的环流型;２）除形成环流处外,其它部分流速、流向在上、下层表现出明显的垂直切变;３）闭合式温度场储存位能,即使在无风和初始静止流场情况下,也可驱动湖流并形成若干环流特征;４）风对水的驱动作用是形成北湖北部稳定环流的决定性因子,并且本身可构造出温度场     

从居民生活视角谈太湖环境保护与治理——太湖与琵琶湖的比较分析

在环境问题日益受到社会关注的今天,环境研究者有必要从社会学和人文学科的角度来关注太湖的环境问题。本文用“生活环境主义”的观点对近年来在太湖和日本琵琶湖畔实施的调查结果进行分析和比较。得出的基本结论是：两国虽然现代化的时间和经历不同,但居民的生活行为和地域环境变化都有密切的相互影响。在人口稠密地区,只有充分重视生活经验－生活意识－生活行为－地域环境的演进和循环,从技术、经济、居民生活方式等多方面入手才能从根本上解决区域的环境问题。     

日本琵琶湖表面定振波的计算

利用水动力学方程对口本琵琶湖表面定振波进行了计算和分析,结果表明其主要周期约为69．5min,另外,利用实测水位资料,采用最大熵谱法进行分析,得到了主要周期约为68min,两者吻合很好。     

人与自然关系的修复——日本琵琶湖治理与生活环境主义的应用

湖泊的环境、生态问题与流域社会、经济密切相关.如何从社会学的角度认识和解决湖泊所遇到的问题,越来越受到各领域研究者的关注.环境社会学一种理论如何付诸于解决环境问题的实践？尚处于探索过程之中.通过了解日本环境社会学以及生活环境主义的起源和思想,总结日本琵琶湖将生活环境主义思想应用于湖泊治理中的各种方法和实例,分析环境社会学在湖泊治理中发挥的作用.通过环境社会学在琵琶湖的治理中的经验,探讨生活环境主义在湖泊治理中可能发挥的作用.认为在下一阶段的湖泊治理中修复“人与自然的关系”将会成为重要内容.     

Climatic and environmental changes at southeastern coast of Lake Biwa over past 3000 years, inferred from borehole temperature data

In order to infer past climatic change in central Japan, we measured temperatures in a borehole at the Karasuma site, on the southeastern coast of Lake Biwa, and reconstructed sediment surface temperature history during the last 3000 years. The reconstructed temperature history shows apparent Medieval Warm Period, Little Ice Age, and contemporary temperature warming. However, the large amplitude of the temperature changes up to 4-5 K cannot be explained by past climatic change only, suggesting that there was some other cause of the larger amplitude temperature changes. The onsets of temperature decrease in the late 12th century a.d. and temperature increase in the mid 17th century a.d. appear to coincide with occurrences of two destructive earthquakes (1185 and 1662 a.d.) that caused water level changes of Lake Biwa. It suggests that the reconstructed sediment surface temperature history reflects the environmental change due to tectonically induced water level changes of the lake. If the annual mean of the ground surface temperature was higher than that of the bottom water temperature in a shallow part of the lake, which is consistent with the present-day data, the large amplitude of the sediment surface temperature change may be attributed to a combined effect of past climatic and environmental changes. Thus, we suggest that the borehole temperature at the Karasuma site preserves information not only on past climate changes but also on environmental changes due to tectonically induced water level changes.     

Cyanobacterial blooms in Lake Atitlan, Guatemala

Lake Atitlan, one of the most important lakes not only in Central America but in the whole world, is facing serious problems with increasing water pollution. Over the last several decades, the uncontrolled nutrient input into the lake has lead to high P levels and low N:P ratios, initiating cyanobacterial blooms. The first bloom occurred in December of 2008, followed by more extensive bloom in October 2009. The blooms are formed by cyanobacteria from the rare planktic Lyngbya hieronymusii/birgei/robusta complex. Based on the species morphology, the Atitlan population corresponds to L. robusta and this is the first case of reported bloom of this species worldwide. Remote sensing images documented that at the maximum bloom development, 40% of the 137 km² of the lake area were covered by dense patches of Lyngbya, with the chlorophyll a concentration reaching over 100 μg L⁻¹. The only toxins detected in the 2009 bloom were trace levels of cylindrospermopsin and saxitoxin with 12 and 58 ng g⁻¹, respectively. The nitrogen fixation followed a pattern expected in non-heterocytous cyanobacteria, i.e., the nitrogenase activity was minimal during the day, while during the night the activity reached 2.2 nmol C₂H₄ μg Ch a⁻¹ h⁻¹. Delta ¹⁵N of −0.86‰ was well in the range given for nitrogen fixing organisms. The cell C, N and P content was 36.7%, 5.9% and 0.9%, respectively, resulting in the molar ratio of 105:14.4:1. A well designed and executed lake monitoring program, strict control of nutrient input into the lake, and public education are the necessary prerequisites for potential prevention of even more severe blooms than the one from 2009.     

巢湖、太湖蓝藻湖靛及其提取物的动物毒性初步研究

对国内淡水湖泊巢湖、太湖中的蓝藻湖靛及其提取物（藻胆蛋白）,进行了动物毒性实验。实验动物为昆明种小白鼠,采用灌胃法给药。给药后小白鼠均无中毒症状,一周内无死亡。说明巢湖、太湖中蓝藻湖靛及其提取物,对以小白鼠为代表的哺乳类动物消化系统,基本不产生毒性。这对于开发两湖中的蓝藻作为鱼、家禽等饲料和提取其中的植物蛋白（藻胆蛋白）作为营养食品添加剂等有一定意义。