大理西湖湿地景观中水体富营养化及截留功能的季节变化

科学评估湖泊型湿地水体富营养化及截留功能在季节及空间的变化规律对评价湖泊水环境质量、分析污染来源、改善湖泊水体富营养化和湿地/流域生态可持续具有重要意义.以大理洱海流域源区的西湖湿地4种景观分区下的水体为对象,分别于2019年4月(旱季末期)和10月(雨季末期)各采集32个水样,测定其总磷(TP)、总氮(TN)浓度,以...     

多重环境压力下大屯海硅藻群落结构的长期变化

云南亚热带高原湖泊在过去几十年内面临着工业污染、富营养化、滩地围垦、极端干旱等多重环境压力的影响.本研究以大屯海为研究对象,结合沉积物硅藻、粒度、碳氮同位素以及年代序列等数据进行了多指标分析,重建并识别了大屯海近百年来生态环境变化的历史和硅藻群落变化的特征.结果表明： 近百年来硅藻群落组合出现了较大的转变,优势种由连接脆杆藻转变为极细微曲壳藻.结合多指标环境记录(如碳氮同位素)和现代监测记录,采用排序分析以及方差分解发现,工业污染和湖泊营养盐富集是大屯海硅藻群落结构长期变化的主要驱动因子.此外,沉积物粒度分析结果与气象数据显示,由于大屯海受到修建大坝以及多次干旱事件的影响,湖泊水动力与水体交换能力减弱,从而使沉积物硅藻群落结构也发生了相应的变化.     

疏浚后杭州西湖浮游动物群落的变化

2003年1-12月调查了疏浚后杭州两湖(小型、浅水、富营养化湖泊)四个采样站(Ⅰ-Ⅳ)浮游动物群落的变化。研究包括优势种组成、密度和生物量,以及浮游动物生物量与水体叶绿素a、有机物耗氧量、总氮和总磷含量之间的相关分析。疏浚后,Ⅲ-Ⅳ站原生动物第一优势种由似铃壳虫(Tintinnopsis sp.)变为筒壳虫(Tintinnidium sp.);Ⅲ-Ⅳ站轮虫第一优势种由暗小异尾轮虫(Trichocerca pusilla)变为针簇多肢轮虫(Polyarthra trigla);Ⅰ站的长额象鼻溞(Bosmina longirostris)和Ⅲ站的微型裸腹溞(Moina micrura)分别取代了长肢秀体溞(Diaphanosoma leuchtenbergianum)第一优势种的地位;桡足类中,剑水蚤优势种为粗壮温剑水蚤(Thermocyclops dybowskii),哲水蚤优势种为汤匙华哲水蚤(Sinocalanus dorrii)。疏浚后,西湖浮游动物平均密度增加了80.5%,其中原生动物密度增量贡献57.3%。平均生物量增加了49.7%,其中轮虫生物量增量贡献36.5%。西湖浮游动物生物量与水体叶绿素a、有机物耗氧量和总磷含量之间均呈垃著的正相关关系。不同采样站中,以Ⅳ站环境生态因子与浮游动物生物量之间的相关程度最高,其次为Ⅲ站、Ⅰ站和Ⅱ站,水体环境生态因子对浮游动物的影响程度与其优势利演变的体现相一致。在不同浮游动物类群中,枝角类生物量与水质生态因子之间的相关程度最高,其次为轮虫、桡足类和原生动物。     

桂江流域附生硅藻群落特征及影响因素

研究了桂江流域水质、土地利用、地理因素对河流附生硅藻群落的影响。结果显示,桂江流域电导率(Conductivity,Cond.)由下游至源头呈降低趋势,其它水质参数变化趋势不明显。主成分分析(Principle Component Analysis,PCA)显示前两个主成分共解释了56.2%的水质特征,第一轴反映了氨氮(NH4-N)、硝氮(NO3-N)、总氮(Total Nitrogen,TN)的变化梯度,第二轴反映了水温(WT)、pH、Cond.、溶解氧(Dissolve Oxygen,DO)的变化梯度。桂江流域硅藻特定污染敏感指数(Specific PolluoSensitivity Index,IPS)和硅藻生物指数(Biological Diatom Index,IBD)下游低于源头,差异不显著,与多项水质、土地利用以及地理因子呈线性显著相关。24个样地共发现112种硅藻,丰富度大于5%的37种,丰富度最大的几个种类依次为Achnanthidium minutissimum,A.pusilla,A.tropica,Cymbella laevis。对应分析(Corresponding Analysis,CA)显示桂江流域存在3个差异较大的硅藻群落,流域下游以Nitzschia recta为优势种,A.lanceolata、Amphora montan、Planothidium frequentissimum在中下游丰度较高,上游区域种类较多。典型相关分析(Canonical Correspondence Analysis,CCA)排序前两轴解释了硅藻群落变异程度的28.60%,CCA排序轴1与水质(Cond.、WT、NH4-N、NO3-N、TN)和土地利用(城市面积、农田面积、植被覆盖)显著负相关,与地理因素(流域面积、海拔、坡度)显著正相关,第二轴与浊度(NTU)显著正相关(P<0.05)。偏典型相关分析(Partial CCAAnalyses)显示,土地利用、地理因子、水质分别解释了桂江流域硅藻群落变异的7.20%,17.50%,48.50%。结果表明,桂江流域附生硅藻群落结构是水质、地理因子和土地利用共同作用的结果,水质起决定性作用,电导和不同形态的氮是影响附生硅藻群落结构的主要水质因素。     

疏浚工程前后杭州西湖枝角类群落结构的变化

调查了疏浚工程前(1995年)与疏浚工程后(2003年)杭州西湖四个湖区枝角类的群落结构,包括密度、生物量、多样性指数以及优势种组成的变化,并对枝角类生物量与水质理化因子之间的相关关系进行了分析。结果表明：西湖枝角类平均密度由1995年的1．86ind／L上升到2003年的4．53ind/L,生物量由1995年的0．051mg／L上升到2003年的0．093mg/L,而多样性指数平均值则由1995年的10．39下降到2003年的4．33。疏浚后,西湖原第一优势种长肢秀体溞(Diaphanosoma leuchtenbergianum)的优势度明显下降,一些体型较小的优势种,如长额象鼻涵(Bosmina longirostris)、颈沟基合溞(Bosminopsis deitersi)和微型裸腹溞(Moina micrura)的优势度均有不同程度的增加：某些湖区长额象鼻溞和微型裸腹溞取代了长肢秀体溞第一优势种的地位。枝角类年平均生物量与水体年平均叶绿素a和总磷含量之间均有显著的负相关关系,并有随水体透明度提高而增加、随pH值增大而下降的趋势。长肢秀体溞、长额象鼻溞和颈沟基合溞在营养水平较低的湖区具有较大的密度和生物量,而微型裸腹溞则在营养水平较高的湖区具有较大的密度和生物量。水体富营养化程度不同被认为是枝角类在湖区间具有不同分布格局的重要原因。     

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。     

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。     

水质对东江流域附生硅藻群落的影响

运用相关分析(CA),典型对应分析(CCA),加权平均分析(WA)研究了影响东江流域附生硅藻的主要水质因子及对应的最适生态范围。CA显示,13项水质指标中溶解氧(Dissolved Oxygen,DO)、氨氮(NH4-N)、亚硝氮(NO2-N)、氯化物(Cl)、五日生化需氧量(BOD5)、磷酸盐(PO4-P)与其它指标间的相关性较强(P0.05),其余指标间相关性较低(P0.05)。以相关性较弱的p H、电导率(Cond.)、硅酸盐(Si O2)、总磷(TP)、总氮(TN)、硝氮(NO3-N)、化学需氧量(CODKMn O4)进行CCA分析,排序显示影响附生硅藻的水质因子依次为Cond.、NO3-N、CODKMn O4、TP、TN,对应的生态最适范围分别为39.20—642.00μs/cm、0.46—2.77mg/L、1.0—5.5mg/L、0.02—0.64mg/L、0.48—3.43mg/L。研究表明,Cond、NO3-N、CODKMn O4、TP、TN是影响东江附生硅藻分布的主要水质因子,Cyclostephanos invisitatus、Gomphonema olivaceum、Nitzschia acicularis、N.capitellata、N.intermedia可以指示东江较高的电导率,Aulacoseira ambigua、A.lirata、Cyclotella meneghiniana、Cyclostephanos invisitatus、Eunotia minor、Nitzschia acicularis、N.Clausii、Pinnularia subcapitata是东江TN、TP污染的指示种。Nitzschia acicularis对TN、TP的耐受性最高,Navicula eidrigiana对TN、TP敏感性最强。     

利用SOFM网络评价杭州西湖水质的时空变化

根据西湖8个采样点2000年1月至12月的常规监测数据和多次模拟调试找出影响西湖水体的主要水质因子作为自组织人工神经网络的输入变量,利用网络的无差别分类能力,建立多指标水质综合评价的自组织特征映射网络(Self-Organizing Feature Map)模型,探索各个湖区不同时段的富营养化状况.结果表明,利用SOFM人工神经网络对西湖水体进行时空分类的结果直观、清晰,从空间上看,小南湖的水质较好,而北里湖的较差;从时间上看,一、二月份水质较好,五到十月份水质较差.说明人工神经网络模型能有效合理的模拟富营养化进程中的非线性行为,并能准确评价西湖水质的富营养化状况,为及时有效的提出控制措施提供科学的依据.     

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。     

Non-siliceous algae in a five meter core from Lake Kinneret (Israel)

The composition and succession of non-siliceous algae, studied in a five meter core from Lake Kinneret (Israel), are described. Only Chlorophyta species were recorded, probably due to the standard palynological sample processing which was used. In the lower part of the core, from the bottom to 300 cm (interval 5500–2500 years B.P.), Botryococcus braunii was the only common alga. Relevant changes in algal diversity and abundance occur at 300 cm. Many species of green algae were recorded for the first time (Pediastrum, Scenedesmus, Coelastrum, etc.). These changes may be related to an increase in nutrient concentration as a consequence of cultural disturbance. In the interval 300-0 cm, a succession of Pediastrum species is followed. The recovered green algae are extant in the present plankton of Lake Kinneret. They also constitute an important part of the algae found in the profundal sediments today.     

Diatom assemblages in superficial sediments from the Gulf of Riga,eastern Baltic Sea

Twenty one superficial sediment samples from areas of high and moderate eutrophication in the Gulf of Riga were studied with respect to siliceous microfossils, mainly diatoms.The results seem to imply that the number of taxa and the abundance of the frustules are affected by runoff from rivers and the degree of eutrophication in different parts of the Gulf. Areas with high eutrophication, e.g. the river estuaries, have diatom assemblages of varying composition, while in areas with moderate eutrophication the composition is almost constant and the influx of freshwater diatoms and littoral periphyton small. The high abundance and low diversity of brackish-marine and brackish, planktonic diatoms seem to be a result of an influx of nutrients and pollutants in the water and bottom sediments. The sea ice diatoms occurring in the Baltic waters and also in the Gulf of Riga tend to be resistant to eutrophication or are even favoured by it.     

Vertical distribution and release characteristics of phosphorus forms in the sediments from the river inflow area of Dianchi Lake,China

Columnar sediment samples were collected from five representative river inflow areas of Dianchi Lake, China. The vertical distribution of each form of P were tested. Results showed that the concentration of TP in the sediments from areas A, B, C, D and E in the order of D > B > A > C > E, and the average concentration of D, B, A, C and E were 2991, 2064, 1308, 879, and 759 mg?kg^?1, respectively. The concentration of Ex-P, Fe/Al-P, Ca-P and Org-P all decreased with increasing depth. The release of Ex-P was significantly related to TP whereas the Fe/Al-P was not significantly related to TP in the samples from areas polluted by domestic sewage. However, the release of Ex-P and Fe/Al-P were both significantly related to TP in the samples from areas polluted by phosphate mining and phosphate fertilizer application. The results of equilibrium P concentration (EPC0) analysis showed that P in the sediments of areas A, D and E were the source of P in Dianchi Lake, and the P in the sediments of areas B and C were in relative equilibrium with the overlying water.     

Combining limnological and palaeolimnological data to disentangle the effects of nutrient pollution and climate change on lake ecosystems: problems and potential

1. As long‐term observational lake records continue to lengthen, the historical overlap with lake sediment records grows, providing increasing opportunities for placing the contemporary ecological status of lakes in a temporal perspective. 2. Comparisons between long‐term data sets and sediment records, however, require lake sediments to be accurately dated and for sediment accumulation rates to be sufficiently rapid to allow precise matching with observational data. 3. The critical role of the sediment record in this context is its value in tracking the changing impact of human activity on a lake from a pre‐disturbance reference through to the present day. 4. Here, we use data from a range of lakes across Europe presented as case studies in this Special Section. The seven sites considered all possess both long‐term observational records and high‐quality sediment records. Our objective is to assess whether recent climate change is having an impact on their trophic status and in particular whether that impact can be disentangled from the changes associated with nutrient pollution. 5. The palaeo‐data show clear evidence for the beginning of nutrient pollution varying from the mid‐nineteenth century at Loch Leven to the early and middle twentieth century at other sites. The monitoring data show different degrees of recovery when judged against the palaeo‐reference. 6. The reason for limited recovery is attributed to continuing high nutrient concentrations related to an increase in diffuse nutrient loading or to internal P recycling, but there is some evidence that climate change may be playing a role in offsetting recovery at some sites. If this is the case, then lake ecosystems suffering from eutrophication may not necessarily return to their pre‐eutrophication reference status despite the measures that have been taken to reduce external nutrient loading. 7. The extent to which future warming might further limit such recovery can be evaluated only by continued monitoring combined with the use of palaeo‐records that set the pre‐eutrophication reference.     

Diatoms of surface sediments of Utah Lake,Utah, U.S.A.

Diatoms in fifty-seven surface sediment samples from Utah Lake were examined. Three hundred and fifteen taxa in forty-three genera were identified and quantified. Statistical analyses of the data showed that distinct geographical subregions of the lake could be delineated according to population patterns of the bottom sediment diatoms. In particular, both Provo Bay and Goshen Bay were distinct from each other and from other areas of the lake.     

The trophic history of Enäjärvi,SW Finland,with special reference to its restoration problems

The eutrophicated Enäjärvi was studied by paleolimnological analyses and sediment mapping. The sedimentary record indicates that the lake nutrient balance had deteriorated due to lowering of the lake water level in the year 1928. From that event onwards Chironomus plumosus and Cyclotella astraea characterize the chironomid and diatom communities. The concentrations of sedimentary total and mobile phosphorus show that since then the internal load of phosphorus has controlled the nutrient cycle of the lake. The areal distribution of mobile phosphorus can be explained by dominant wind directions and wind resuspension of the sediment is the key factor in the nutrient cycle. Restoration of Enäjärvi must be based on actions which stabilize the surface sediment and improve its natural phosphorus-binding capacity. They include the regulation of lake water to as high a level as possible and the removal of the majority of roach.     

Diatoms from surface sediments of the northern part of Lake Tanganyika

227 Diatom taxa were observed in the surface sediments of the northern part of Lake Tanganyika, including 1 new to science: Amphora tanganyikae. The diatom community of these sediments is mainly composed of benthic organisms while planktonic diatoms are rather rare. Many brackish-water and a few marine organisms were observed. Cosmopolitan organisms (77.1%) dominate the diatom flora but tropical, tropical African and African taxa are also well represented (22.9%)Deceased.Deceased.