近40年洞庭湖区内湖水面面积变化及其驱动因素

选择1979-2016年间多时期、多类型、多光谱遥感数据,分析评价洞庭湖区内湖近40年的面积变化.结果表明,最近40年洞庭湖区内湖面积保持相对稳定,丰水期间呈上升趋势,枯水期间波动下降,2016年内湖总面积比1980s初减少3.94%.随着湖泊面积增加,湖泊水面面积变化的比例和幅度逐渐减小,大型湖泊（>10 km²）和中型湖泊（5~10 km²）面积相对稳定,小型内湖（<5 km²）面积变化尤为剧烈.内湖水面面积主要受降雨、蒸发等气候因素和生产生活取水、防洪排涝和退田还湖等人为活动调控.1980-2000年和2001-2015年两个时期,洞庭湖区多年平均降雨量呈现不同程度的下降趋势,多年平均蒸发量明显上升.三峡工程运行后,三口分流衰减,但水资源需求量不断增长,退田还湖和留蓄雨洪作为水资源使得丰水期间内湖水面面积增长,气候变化和水资源开发利用导致枯水期水面面积趋于减少.有必要加强洞庭湖区内湖的研究和保护,适当退田还湖提高湖泊率,优化三口水系格局,实施河湖水系连通工程,缓解洞庭湖区季节性水资源紧张问题.     

城市湖泊水环境修复组合工艺效果研究——以深圳市荔枝湖治理工程为例

以深圳市荔枝湖为例,通过历时9个月的水质连续监测,研究该湖水污染综合治理工程实施后不同治理工艺的处理效果.研究表明,自动过滤工艺TP和COD平均去除率分别为33.6%和16.2%;生物砾石床工艺TP和COD平均去除率分别为39.O%和21.3%;人工湿地工艺TP和COD平均去除率分别为80.2%和56.1%.通过荔枝湖四湖总磷串联模型,计算在设计初始条件下,采用组合治理工艺时湖水恢复为地表Ⅳ类水所需要的时间.计算表明工艺每天运行24h,需要2.5d可将各湖TP浓度降至O.1mg/L以下,TP总去除量为7.27kg,去除率为46.%.     

Development of microsatellite loci for two Agabus diving beetle species from the pooled DNA and testing their utility in mountain lake populations

Diving beetles (Dytiscidae) are the most speciose water beetle group, occurring on all continents except Antarctica. They inhabit various lotic and lentic habitats and play an important role in ecosystem functioning. In this study, we developed functional polymorphic microsatellites for two widely distributed species from one of the most diversified dytiscid genus Agabus: Agabus bipustulatus (Linnaeus, 1767) and Agabus cf. guttatus from the Agabus guttatus group sensu Foster and Bilton (1997). For microsatellites development, pooled DNA and NGS pyrosequencing were used. Microsatellites are still very useful genetic markers for studying recent population changes, but for dytiscids, highly diversified and ecologically important group of freshwater invertebrates, only 8 microsatellite loci are available for one North American species. To test utility of the developed markers, we used several populations of alpine lakes, situated in the Tatra Mountains (Western Carpathians). From the 60 tested markers, 13 loci for Agabus bipustulatus and 8 loci for A. cf. guttatus showed polymorphism. The number of alleles per locus varied from 2 to 10 and no significant linkage disequilibrium was observed. Observed/expected heterozygosity varied from 0/0.077 to 1/0.834 within populations of A. cf. guttatus and from 0/0.056 to 1/0.837 within populations of A. bipustulatus. The significant deviation from HWE was probably caused by presence of null alleles or undetected biological processes. Bayesian cluster analysis revealed differences in the cluster proportions, confirming applicability of the developed markers for future studies of population structure of both Agabus species.     

营养状态指数在长江下游小型浅水湖泊富营养化水平评价中的局限及改进建议

基于多个环境变量、以等权或者加权平均法获得的综合营养状态指数（Carlson指数：TSIc;修正后的Carlson指数：TSImc;综合营养状态指数：TLIc;湖库营养状态指数：EIc）得分是当前评价湖泊营养水平的主要依据,其值计算时先要获得基于单个环境变量的营养状态指数分值。若基于总氮（TN）、总磷（TP）和透明度（SD）等的单个理化指标与基于叶绿素a(Chl.a)的营养状态指数得分间存在显著差异,表明依据理化指标的评估结果低估或者高估湖泊的实际营养水平。长江下游分布大量的小型浅水富营养化湖泊,但基于理化指标的评估结果是否会误判湖泊的实际富营养化水平的研究很少。本研究以长江下游的14个浅水富营养化湖泊为对象,于2019 2020年按照季度采集水样并测定水环境因子,分析基于理化指标和基于Chl.a的各营养状态指数（TSI、TSIm、TLI和EI）得分间的差异。结果表明,基于SD的TSI、TSIm、TLI和EI的年均得分均显著高于基于Chl.a的相应营养状态指数的年均值;除TSI(TP)vs.TSI(Chl.a)外,基于TP与基于Chl.a的其他营养指数的年均得分间均有显著性差异;仅TL...     

Modelling climate change impacts on hydropower lake inflows and braided rivers in a mountain basin

This study models climate change impacts on the natural flow regime of braided rivers and inflows to hydropower lakes in a New Zealand mountain basin. Flow metrics include the magnitude, frequency, timing and duration of unaltered flows. The TopNet hydrological model was used to simulate impacts in the Upper Waitaki Basin of the South Island for the 1990s, 2040s and 2090s. An average emissions scenario and results from 12 global circulation models were used as input. Indicators of hydrological alteration and Kruskal-Wallis tests were used to evaluate flow differences. Modelled total inflows increase over time for all lakes, with most increases in winter/early spring and small decreases in summer/autumn. High flows generally increase, while low flows decrease. Although these changes may benefit hydropower and floodplain ecology, they may increase flood risk in winter and spring and drought risk in summer and autumn, causing additional challenges managing hydropower operations.

EDITOR M.C. Acreman

ASSOCIATE EDITOR S. Kanae     

Can be the environmental and biotic factors responsible for macroinvertebrate communities’ alterations in Portuguese alpine ponds?

Alpine ponds are shallow waterbodies formed in alpine zones characterized by usual pristine conditions, however subject to harsh conditions that enable the emergence of unique communities with high conservational value. Therefore, it is important to gather information about these ecosystems and understand the changes in the biota. This work aimed to use Portugal’s alpine ponds as a case of study in assessed the macroinvertebrates communities in the Mediterranean ecozone. To fulfill this goal, we aimed to understand the alterations on macroinvertebrates community and how are they modulated by environmental variables. Five alpine ponds in Serra da Estrela (Portugal) were studied for one year. Macroinvertebrate communities and physical and chemical water parameters were determined in June/16, October/16, and April/17. Water chemistry values were similar to other studied lentic waterbodies in alpine zones in Europe, with slightly acidic water and low conductivity. Although accentuated macroinvertebrates differences between ponds, no significant differences in diversity were recorded, indeed the main differences recorded were influenced by ponds habitat types and environmental variables. Canonical Correspondence Analysis showed differences in the communities between ponds, namely the high influence of several physical and chemical parameters (conductivity, phosphate content, and pH) in the macroinvertebrates community composition. Indeed, Spearman’s correlation revealed significant interaction in diversity, abundance and richness of macroinvertebrates and several physical and chemical parameters (pH, dissolved oxygen and nitrates concentration).     

Delineating extent and magnitude of river flooding to lakes across a northern delta using water isotope tracers

Hydrological monitoring in complex, dynamic northern floodplain landscapes is challenging, but increasingly important as a consequence of multiple stressors. The Peace-Athabasca Delta in northern Alberta, Canada, is a Ramsar Wetland of International Importance reliant on episodic river ice-jam flood events to recharge abundant perched lakes and wetlands. Improved and systematic monitoring of landscape-scale hydrological connectivity among freshwater ecosystems (rivers, channels, wetlands, and lakes) is needed to guide stewardship decisions in the face of climate change and upstream industrial development. Here, we use water isotope compositions, supplemented by measurements of specific conductivity and field observations, from 68 lakes and 9 river sites in May 2018 to delineate the extent and magnitude of spring ice-jam induced flooding along the Peace and Athabasca rivers. Lake-specific estimates of input water isotope composition (δ_I) were modelled after accounting for influence of evaporative isotopic enrichment. Then, using the distinct isotopic signature of input water sources, we develop a set of binary mixing models and estimate the proportion of input to flooded lakes attributable to river floodwater and precipitation (snow or rain). This approach allowed identification of areas and magnitude of flooding that were not captured by other methods, including direct observations from flyovers, and to demarcate flow pathways in the delta. We demonstrate water isotope tracers as an efficient and effective monitoring tool for delineating spatial extent and magnitude of an important hydrological process and elucidating connectivity in the Peace-Athabasca Delta, an approach that can be readily adopted at other floodplain landscapes.     

Distinction between the Storegga tsunami and the holocene marine transgression in coastal basin deposits of western Norway

Many coastal lakes were inundated by both the Storegga tsunami (7000 ¹⁴C yr BP) and the mid-Holocene sea-level rise (the Tapes transgression) in western Norway. The tsunami eroded lake bottoms and deposited graded and/or massive beds of sand, rip-up clasts, and coarse plant material. By contrast, when the rising sea entered the lakes, it deposited only gyttja, silt and fine sand, without causing much erosion of the underlying lake sediments. Storegga tsunami deposits in some coastal lakes were interpreted previously as ordinary marine sediments from the Tapes transgression. Our reinterpretation of these deposits shows that the transgression maximum phase was reached after 6500 yr BP, more than 1000 yr later than previously inferred for the coast of Sunnmøre. The new data cannot be combined in a shoreline diagram without showing the 6000 yr BP and 7000 yr BP shorelines as slightly warped. © 1998 John Wiley & Sons, Ltd.     

Environmental change in Northern Egyptian Delta lakes during the late Holocene,based on diatom analysis

Quantitative and qualitative diatom analyses from the north Nile Delta lakes sediments of Egypt were used to evaluate the paleoenvironmental development of the lakes and climatic changes during the late Holocene. We analyzed 565 samples taken from 19 cores from Manzala, Burullus and Edku lakes. A total of 263 diatom species and varieties were identified. Multivariate statistical analyses distinguished 17 ecological groups that reflect changes in water salinity, lake-level and trophic state of the lakes, which in turn are mainly related to climatic changes and anthropogenic impacts. Manzala and Burullus lakes experienced a series of alternation between fresh, brackish and marine episodes, which were associated with wet and dry climates. Edku Lake cores, however, contained only three ecological groups that are characteristic of brackish water conditions. The general depositional regime in the lakes indicated five environmental phases: (a) a deep freshwater phase when the Nile flood water reach the lakes during humid warm climate; (b) a shallow freshwater phase with some macrophytes during a dry climate; (c) a shallow brackish water phase when Nile floodwater ceased during a dry climate and the lakes shifted to brackish conditions; (d) a mixed environmental phase when the seawater mixed with freshwater from drains and canals (water salinity fluctuated widely from freshwater to estuarine and full marine conditions); (e) a fully marine phase when seawater entered the lakes at all stages of the tide.