大理西湖流域开发历史与硅藻群落变化的模式识别

有关云南湖泊的研究长期集中于高原九大湖泊和水体富营养化评价,缺少对中小型水体及多重环境压力胁迫的综合研究.本文以大理西湖为例,结合沉积物记录与现代监测资料,甄别了气候变化和人类活动干扰下硅藻群落结构的长期响应模式及其驱动强度.结果表明: 20世纪50年代以前,大理西湖总体处于自然演化阶段;1950年代开始,围湖造田和流域改造的增强导致了水体营养水平增加、水动力条件改变,硅藻优势种由扁圆卵型藻替代为脆杆藻属;而1997年以来营养水平的快速增加和湖泊水动力的改变,促进了浮游藻类大量生长、底栖硅藻持续减少,同时水生植物快速退化、生态系统稳定性明显降低.因此,在长期流域开发的背景下,对云南中小型高山湖泊的有效保护需要评价流域开发类型、强度及全球变暖的长期影响.     

好氧反硝化菌脱氮特性研究进展

好氧反硝化菌的发现,是对传统反硝化理论的丰富与突破. 由于其在脱氮方面的独特优势,已成为目前废水生物脱氮领域研究的热点. 好氧反硝化菌能够在有氧条件下,利用有机碳源生长的同时将含氮化合物反硝化生成N2等气态氮化物,多数还能同时进行异养硝化作用,将铵态氮直接转化为含氮气体. 本文从电子理论、反硝化酶系等方面对目前已分离出的一些好氧反硝化菌的脱氮特性及其脱氮机理进行探讨,分析了溶解氧、碳源类型及C/N等环境条件对其脱氮作用的影响,介绍了好氧反硝化菌的筛选方法及应用现状,对其应用前景和发展方向进行了展望.     

星云湖硅藻群落响应近现代人类活动与气候变化的过程

随着人类活动的增强与全球气候变暖的持续,近年来云南湖泊的生态系统功能持续退化,而目前对云南湖泊生态系统的研究还主要集中于单一环境压力的生态效应。以星云湖为研究对象,通过沉积物记录与现代监测资料,识别在湖泊富营养化、气候变化以及人类强烈干扰下硅藻群落结构响应的过程,并甄别驱动群落变化的主要环境压力及其强度。结果显示随着湖泊生产力水平(如沉积物叶绿素a浓度)的增加,硅藻物种组成发生了明显的变化,主成分分析表明了水体富营养化是驱动群落变化的主要环境因子(r=-0.63,P0.001)。简约模型与方差分解的结果表明近200年来(钻孔长度38cm),湖泊营养水平和水动力是驱动星云湖硅藻群落变化的主要环境因子,分别解释了群落变化的18.8%和2.9%;而1951年以后,湖泊营养水平和温度分别解释了硅藻群落结构变化的31.4%和26.8%。研究结果表明了硅藻群落长期变化的主控因子是湖泊营养水平,而人类活动及气候变化等可以通过改变湖泊水动力及湖水温度来驱动硅藻群落的演替,同时抚仙湖-星云湖的连通性也对硅藻群落的演替产生了一定影响。     

水文气候波动下云南太平水库硅藻群落演替的长期特征

在区域气候变暖的背景下,干旱事件引起的水位频繁波动以及流域开发导致的污染物输入均可以直接威胁水库的生态安全.本研究以云南省太平水库为对象,通过对沉积物的物理(粒度、烧失量)、化学(碳、氮元素)、生物(硅藻群落)等代用指标的分析,并结合监测数据和调查资料,重建了该水库1937-2018年的生态环境变化过程,并识别了硅藻群...     

抚仙湖和滇池硅藻生物多样性与生产力关系的时间格局

目前国内对生产力–生物多样性关系(productivity–diversity relationship,PDR)的研究主要集中于陆地生态系统和空间尺度,少量关于湖泊系统的研究也主要集中于现代调查,缺乏较长时间尺度上的模式探讨。本文应用沉积物色素记录重建了抚仙湖和滇池初级生产力变化历史,对硅藻群落的主成分分析(PCA)表明两个湖泊的初级生产力都是驱动硅藻群落变化的主要环境梯度。进一步分析硅藻群落α与β多样性响应湖泊生产力水平的模式,发现滇池硅藻群落表现为随着系统生产力的上升物种丰富度减少,β多样性降低,而抚仙湖呈现相反的变化模式。两个湖泊β多样性与生产力平均水平的关系均表现出与α多样性相似的特征,但在与生产力变化幅度的关系上,滇池表现出显著的负相关,而抚仙湖则没有显著的变化。滇池硅藻群落生产力随硅藻多样性的降低显著增加(R2=0.597,P0.01),而在抚仙湖无显著变化,表明了滇池群落多样性的维持对群落生产力的影响较弱,如与营养盐富集的促进作用相比。滇池明显的富营养化过程与强烈的人类扰动带来的环境异质性降低可能对群落多样性–生产力的关系产生了明显的控制作用。     

昆明小型城市湖泊叶绿素a浓度与硅藻群落的时空分布及主控因子

水体叶绿素a浓度(Chla)与硅藻群落特征是指示湖泊水质的常用生物指标。本研究于2017年3月—2019年12月调查了昆明市4个小型湖泊(云南师范大学校园内北潭、北湖、南湖、龙潭)的水体环境指标、Chla浓度和硅藻群落的季节变化。结果显示：4个湖泊水体总氮(TN)、总磷(TP)和Chla浓度均呈现明显的季节波动。其中,营养水平最高的南湖水体Chla含量显著高于其他3个湖泊,影响南湖Chla变化的主要因子是TN;而在其他3个水体中,水温的增加显著促进了Chla浓度的上升。水温和TN是4个湖泊水体Chla时空变化的主要驱动因子。北潭、南湖和龙潭的硅藻群落以浮游硅藻占优,水深最浅的北湖以底栖硅藻为主,表明水深影响了硅藻群落的浮游物种占比与优势属种。水深、TN、TP、透明度以及水温驱动了硅藻群落的时空变化,其中,水温是影响硅藻群落季节差异的主要因子,而TN和TP是导致同一季节湖泊间硅藻群落差异的主要因子。     

长期砷胁迫下大屯海浮游植物群落的季节性特征及其驱动因子

重金属是影响湖泊水质和生态健康的重要胁迫因子,系统识别生物对长期污染胁迫的响应模式是开展污染湖泊生态修复的重要基础.本研究以经历持续砷污染的大屯海为研究对象,于2017年6月—2018年3月对水体浮游植物和环境因子开展季节性调查.结果显示:大屯海的浮游植物群落主要由蓝藻门组成,与已有研究反映的长期砷胁迫下浮游植物组成以...     

乌梁素海富营养化湖泊湖滨湿地过渡带细菌群落结构的高通量分析

摘要:【目的】揭示乌梁素海富营养化湖泊湖滨湿地沉积物与土壤过渡带细菌群落的组成、丰度以及多样性变化,结合土壤理化因子探讨其对细菌群落结构的影响。【方法】采用湿地土壤总DNA提取方法提取沉积物和土壤总DNA,对细菌群落的16S rRNA 基因的V1-V3区进行高通量测序,分析各样品中细菌群落结构的组成、丰度以及多样性指标;土壤理化性质采用标准方法测定,分析其对细菌群落结构的驱动作用。【结果】富营养化湖泊湖滨湿地水陆过渡带的芦苇沼泽沉积物、碱蓬群落盐碱化土壤和白刺群落荒漠化土壤中,细菌群落组成和各类群细菌的相对丰度差异较大,门水平上的细菌类群主要有Proteobacteria、Bacteroidetes、Chloroflexi、Actinobacteria、Planctomycetes和Gemmatimonadetes,细菌群落多样性指数随陆向分布依次在增高,门水平上Proteobacteria和属水平上Sulfurimonas对湖泊退化演化敏感;环境因子最佳子集为总磷、水溶盐总量和铵态氮的组合对整个细菌群落结构的影响最为明显,相关系数最高(R=0.8857),Mantel检验结果表明这种相关关系为显著相关(P=0.037)。【结论】乌梁素海富营养化湖泊湖滨湿地过渡带细菌群落结构差异较大,Sulfurimonas属在乌梁素海富营养化湖泊沉积物的生物地球化学循环中扮演着重要的角色,应在以后的研究中得到更多的关注。     

苏州河沉积物中硅藻的垂直分布与水质变化

分析了苏州河2个柱状沉积物样品中硅藻种类和丰度的垂直变化,同时采用210Pb测年法推测沉积物的沉积速率,并进行了有机质含量分析,以了解苏州河在不同年代的水质变化。结果表明,2个柱状沉积物中硅藻的优势属为小环藻属、直链藻属、舟形藻属、圆筛藻属和针杆藻属。优势种为梅尼小环藻、瞳孔舟形藻和变异直链藻。就硅藻丰度而言,总趋势是上层最多,平均4.04~25.18×104ind/g;下层其次,平均1.41~4.43×104ind/g;中层最少,平均0.91~2.30×104ind/g。硅藻种类数变化虽无明显规律,但种类最少的样品仍出现在中层,210Pb测年数据表明中层为20世纪60~80年代。相关分析表明硅藻丰度与有机质含量呈显著正相关(p<0.01))。本文结果表明,沉积物中硅藻可以反映苏州河的污染历程:20世纪40~50年代初,水质尚可,但已有富营养化现象,表现在硅藻数量和丰度均较高;50年代中后期开始出现较严重的工业污染,到20世纪70~80年代污染加重,表现在中层沉积物中硅藻种类和数量均减少;进入20世纪90年代,水质有所改善,上层沉积物中硅藻种类和数量又逐渐增多,这与90年代以后加大对苏州河治理力度有关。     

云南程海湖泊系统响应富营养化与水文调控的长期模式

流域开发和气候变化背景下,逐渐增强的人类活动已经显著影响湖泊系统演替及功能。本研究以云南程海为研究对象,通过对程海湖泊沉积物记录与现代调查数据相结合,重建了程海近250年来的生态环境变化过程,探讨了程海湖泊系统在富营养化以及水文波动等多重环境压力影响下的长期响应模式。结果表明: 1970年之前程海营养水平整体偏低,1970—2000年间缓慢增长,2000年后快速增加,初级生产力呈长期上升趋势。1993—2000年期间,引水工程显著增加了湖泊水动力强度和物种扩散能力,促进了直链藻和菱形藻的增加。程海沉积物记录的碳循环变化主要受内源输入的长期影响。富营养化是硅藻群落长期演替的主要驱动因子,其次是湖泊水动力条件的波动。对程海的生态修复与流域管理不仅需要关注水体营养盐的富集与流域污染物的控制,同时还要考虑到湖泊水文调控和水位波动的影响。     

Predicting dominant phytoplankton quantities in a reservoir by using neural networks

A 14.6 m long profile from the northern part of the Hulun lake, the furthest north of the large lakes of China, has provided a sedimentary and diatom record since the late Glacial. The chronological sequence was established based on 10 radiocarbon dates. Sedimentological study and diatom analysis are synthesized for the reconstruction of the history of lake-level changes. The results show that the Hulun basin was not occupied by a lake during the Last Glaciation. A rapid transition to a deep lake occurred since 12850 yr B.P., and this high level phase lasted to 11200 yr B.P., although there existed several subordinate lake level fluctuations. An abrupt lake level drop and dry climatic conditions occurred during 11200–10600 yr B.P. The lake became deeper again from 10600 yr B.P. to 10300 yr B.P. Hulun lake at the early Holocene was characterized by the low lake-level, and the lake level rose again in 7200–5800 yr B.P., though the lake-levels changed quite variably. A dry condition occurred and lake level declined again during 5800–3000 yr B.P. The presence of the palaeosol on the top of this profile indicates the persistence of low lake levels after 3000 yr B.P. The comparison with the other lake-level records from northern China has suggested that the Hulun Lake shows a different lake level history from the lakes in monsoon areas.     

Interactions of temperature and nutrient changes: effects on phytoplankton in the Piburger See (Tyrol,Austria)

1. Contemporary limnological and palaeolimnological data from Piburger See (Eastern Alps, Austria) allowed the reconstruction of its trophic state since the late 19th century and the assessment of changes in phytoplankton biomass and species composition in relation to selected environmental parameters. 2. A radiometrically dated sediment core from Piburger See was analysed for geochemical parameters, spheroidal carbonaceous particles (SCPs), bacterial and algal pigments, and diatoms. The low SCP sediment inventory assigns Piburger See to the ‘cleaner’ sites in Europe with respect to fossil‐fuel related air pollution. The sedimentary pigment and diatom record reveals moderate eutrophication during the 20th century, followed by a slow re‐oligotrophication since the mid‐1980s because of lake restoration starting in 1970. 3. Epilimnetic temperature for Piburger See was reconstructed using air temperature records. A pronounced temperature increase has been recorded during the mid‐1940s and since the late‐20th century, both promoting algal growth and changes in species composition (e.g. increase in centric diatoms and recent bloom of Asterionella formosa). 4. Climate scenarios project additional substantial warming for this mountain lake by the end of the 21st century which will be most pronounced during the growing season. The predicted change in lake water temperature and thermal dynamics represents a key driver for the trophic and ecological status of Piburger See in the future.     

The phosphorus status of sediments in a hypertrophic impoundment (Hartbeespoort Dam): implications for eutrophication management

The phosphorus status and distribution of sediments in a hypertrophic water supply reservoir (Hartbeespoort Dam) were investigated, with a view to assessing the role of sediments in counteracting the effects of reduced external phosphorus loading as a restoration measure. In comparison with similar water bodies in South Africa, the sediments in Hartbeespoort Dam contained high levels of both total and potentially mobile phosphorus. The potentially mobile fraction constituted about 60% of the total phosphorus content of the sediments, compared with about 11% in other reservoirs. The excessive eutrophication of Hartbeespoort Dam is clearly reflected in the phosphorus status of the sediments. Sediment distribution in the impoundment was found to be extremely heterogeneous, due to the combined influences of morphometry, hydrology and an imbalance in the nutrient loads entering via rivers at remote points in the water body. It is concluded that sufficient mobile phosphorus has accumulated in the sediments to prolong the response time of the impoundment to phosphorus load reductions. Since phosphorus release from sediments is dependent on dynamic processes not addressed in this study, the extent of the delays in trophic response to load reduction cannot be estimated.     

Lake restoration with and without dredging of phosphorus-enriched upper sediment layers

Human activity has been the cause of continuing decline of water quality in most Dutch lakes. Development of lake restoration programmes must take into account the lake functions. Major reduction of the nutrient and pollutant loading is the primary step in lake restoration. Still, the recovery of eutrophic lakes is retarded frequently because of internal phosphorus loading by the lakes' sediments. Sediment dredging, as an additional tool for water quality management to accelerate accomplishing the desired water quality, is studied. In this paper we evaluate the preliminary results of eight lake restoration projects in the Netherlands. The lakes are compared in order to estimate the magnitude of the internal phosphorus loading. Dredging as an additional measure was carried out twice in the peatlake Geerplas. In the Nieuwkoop Lakes only the external phosphorus loading was substantially reduced from 0.9 to 0.2 g P m^–2 y^–1. Provisional results of these two shallow peatlake restoration projects focussed on eutrophication abatement with and without dredging, are presented. Both show a decrease in phosphorus concentration in the lakes. The necessity to dredge the lakes is discussed.     

长白山地区硅藻的研究(英文)

长白山是著名的巨型复式火山, 位于我国吉林省东部, 火山锥顶的火口积水成湖, 名曰天池。天池湖水北下入通天河, 后至二道白河。通天河急流形成瀑布, 瀑布东北有大片温泉, 西有常年滴水的石壁。此地区的硅藻前人尚未研究, 经本文研究, 计有硅藻264分类单位, 分别隶属于34属, 其中包括1新变种、2新变型和1新组合。通过此项研究, 阐明该地区的硅藻区系和生态分布特点, 提供研究长白山地区硅藻的新资料。