14C-Photosynthesis of Phytoplankton in an Oligotrophic Alpine Lake (Traunsee,Austria) and its Response to Turbidity Caused by Industrial Tailings

The influence of industrial tailings on the biological integrity of the phytoplankton was assessed from annual measurements of photosynthetic rates in the alpine lake Traunsee. The mean annual integral production of 21 mmol C m^-2 d^-1 corresponded to the oligotrophic nature of the lake. Effects of effluents were tested by comparing photosynthesis at a station close to the industrial outlet (EB) and at a reference site with a maximum depth of 190 m (VI). Between-site optical properties (vertical attenuation coefficient, euphotic depth) were statistically significant different. The euphotic zone at the impacted station was on average 2 m shallower than at the reference site, owing to turbidity emanating from the industrial plant. The adaptation to low light intensities by the algal community at this station was evident from a high maximum light utilisation coefficient (^* at low light saturation (E _K). Algae at the deep reference site were photosynthetically less efficient but adapted to high light intensities. Photosynthetic adaptation to different light climates in the euphotic zone without significant quantitative biomass alterations at the impacted site gave a clear signature of biological integrity of the phytoplankton in the oligotrophic Traunsee.     

Assessment of the Ecological Integrity of Traunsee (Austria) Via Analysis of Sediments and Benthic Microbial Communities

Since nearly one hundred years Traunsee experiences the import of tons of liquid and solid waste originating from salt and soda production. Today, the lake exhibits chloride concentrations of up to 170 mg L^-1 and 19% of the lake floor are directly or indirectly influenced by industrial deposits (ID). Based on the comparison of several microbial parameters in unaffected, directly affected and intermediate lake bottom sediments, the ecological integrity of the lake was evaluated. The highly alkaline ID, which were exclusively colonized by microorganisms, harbored a bacterial community reduced by a factor of 10 in abundance and biomass compared to undisturbed sediment areas within the lake. The bacterial community of ID was furthermore characterized by a reduced content of actively respiring cells (INT-formazan reduction), a lower frequency of dividing cells (FDC) and a significantly reduced cell and biomass production. A 80 to 90% reduction in carbon recycling is estimated for the area exclusively covered by ID. Protists, although occasionally absent from the industrial sediments, were in general found to be less sensitive to the contaminant stress. Differences in alkalinity and dissolved organic carbon (DOC) concentrations of sediment porewaters as well as the total organic content and C/N ratios of sediments partly explain the microbial pattern observed at the various sampling sites. Possible consequences of the continuous industrial tailings for the whole lake ecosystem and the validation of the ecological integrity are discussed.     

Web-Based Information System for Pollution Monitoring of Lake Ohrid

In this paper, we present a Web-based information system for pollution monitoring and analysis of Lake Ohrid. Our work is related to the ecological state of Lake Ohrid, which represents a rare natural ecosystem inhabited by many endemic and relict species. Aim of the study is to present the possibilities offered by the Web application, such as fast information access, support of distributed collaboration by information sharing instead of exchange, acquisition and analysis of pollutant data, database processing based on lake models, as well as GIS analysis. In this way, the data and the analysis are performed in one place and they are available to any user having only a Web browser.     

Watersheds Nutrient Loss and Eutrophication of the Marine Recipients: A Case Study of the Jiaozhou Bay,China

Industrialization and urbanization along the coastal population centers have brought great changes in the land cover and material fluxes from watersheds to receiving bays and estuaries. We have embarked a multiyear research project on “Watersheds Nutrient Loss and Eutrophication of Jiaozhou Bay” for the period of 2000 to 2004, funded by the Natural Science Foundation of China to examine human influence on the marine sector of ecosystem. Jiaozhou Bay, located in the southern part of Shandong Peninsula, was selected because of the existence of long-term hydrographic and meteorological records since the 1930s and recent observations on the marine ecological variables. We have made extensive and periodic measurements on the water movement, nutrients, phytoplankton, and microbe in water column and bottom sediments. Box and 3-dimensional hydrodynamic models were developed and utilized to understand the evolution of eutrophic status with time. It was found that primary productivity has suffered from silica depletion followed by phosphate, and the dominance of large phytoplankton has been replaced by small-size communities. These ecosystem changes were brought by the changes in the relative contribution among major pathways and concentrations, owing to the human activities in the watershed. Eight articles in this volume reported various aspects of the linkage between watershed human activities and ecosystem for the Jiaozhou Bay as the initial outcome of this project.     

In situ Measurement of Daphnia longispina Grazing on Algae and Bacteria in a High Mountain Lake (Lake Paione Superiore,Northern Italy) using Fluorescently Labeled Cells

Grazing impact of Daphnia longispina on phytoplankton and bacteria in Lake Paione Superiore (Northern Italy) was evaluated using fluorescently labeled cells in short-term in situ experiments. Structure and size distribution of Daphnia were studied weekly from its appearance in July to its decline in September. Relative importance of algae and bacteria in the diet varied over time, as did consequently the relative impact of Daphnia on the phytoplankton and bacteria populations. Biomass of bacteria in the diet of Daphnia varied from 1 to 42%, and was highest at the beginning of population development when young individuals dominated. The percent biomass of algae in the diet increased with population development, ranging from 58 to 99%. Daphnia population consumed per hour 0.04–1.8% of bacteria and 0.3–17.6% of phytoplankton abundances.     

Reconstruction of Long-Term Changes in Lake water Chemistry,Zooplankton and Benthos of a Small,Acidified High-Mountain Lake: Magic Modelling and Palaeolimnogical Analysis

Starolesnianske pleso is a small and shallow acid lake in the High Tatra Mountains, situated at 2000 m above sea level, on granitic bedrock, with sparse and thin soil cover. When detailed measurements began in the 1980s Starolesnianske pleso had pH below 5 and only one species of cladoceran zooplankton, the ubiquitous Chydorus sphaericusPalaeolimnological investigations show changes in cladoceran zooplankton and chironomid zoobenthic assemblages since about 1920 and a major change in 1970–1980. The dynamic acidification model MAGIC was used to reconstruct changes in water chemistry over the past 150 years. The results from MAGIC agree well with the sediment record; pH levels gradually decreased from 6.5 in the mid-1800s to about 5.6 in 1920 (first response in biota) to below 5.0 by 1970, and concentrations of inorganic aluminium rose dramatically beginning about 1960. In the 1990s the lake water chemistry showed clear signs of reversal in acidification brought about by a major decline in S deposition.     

Ecological Integrity Assessment of Lakes Using Fish Communities: An Example from Traunsee Exposed to Intensive Fishing and to Effluents from the Soda Industry

In order to analyse potential influences of soda industryeffluents on the ecological integrity of Traunsee (TS) weinvestigated the fish community of the lake in comparison witha reference lake (Hallstättersee HS) and used a reconstructionfrom the (older) literature concerning the original speciescomposition of Traunsee. Published `Index of Biotic Integrity(IBI)' metrics were considered to be of limited value due tothe relatively low species number in the oligotrophic, Alpinelake. Therefore we included, in addition to speciescomposition, studies on egg distribution, larval fishdensities, life-history parameters (i.e. growth, maturity,fecundity, age and size composition), stress levels and heavymetal content of the dominant whitefish (Coregonuslavaretus), as well as overall fish density and biomass (usinghydroacoustics) to assess the ecological status of the fishcommunity. Two of the original 18 species have disappearedfrom the lake, presumably in connection with the introductionof non-native eel (Anguilla anguilla) and theconstruction of a power plant in the outflow. Silt from grindedlimestone together with highly alkaline pore waters is emittedvia industrial wastewater from Sodaworks and covers part of thelake bottom. We observed that eggs of whitefish were spawnedmainly in the main inflowing river and close to the shore, thusavoiding the silty areas and making the anticipated damage tothe reproductive potential of whitefish neglectable. This wascorroborated by larval surveys done weekly on both lakes fromJanuary to May, which showed halve the density of whitefishlarvae in TS compared to HS. Estimates of potentially spawningfish from hydroacoustic surveys resulted in a ratio of 1(TS) :3 (HS). Analysis of whitefish revealed that they are growingfaster in TS and have higher fecundity leading to somecompensation of lower abundance. High levels of fishing in TSmight have led to this pattern and to depressed yields asindicated by the age composition. Level of oxidative stress andheavy metal content were not discernible from the referencelake. Therefore we concluded that negative impacts on theecological status of the fish community resulted from fisheriesmismanagement and a power plant situated in the outflow of thelake, considered to have damaged spawning places for somespecies, but not from soda industry effluents.     

Epilithic Diatoms in an Alpine Lake (Traunsee,Austria) Affected by Soda and Salt Mining Industries

Traunsee, a 191 m deep Alpine lake in Austria, is affected by industrial tailings from the soda and salt mining industries since 1883. In 1998 littoral water chloride concentrations ranged between 40 and 85 mg L^-1 and the highest conductivity was 560 S cm^-1, which is almost double as high as the values reported from the two nearby reference lakes. Chloride concentrations increased towards the location of the industrial salt and soda emission into the lake. Analogously to the chloride gradient, the epilithic littoral diatom flora changes towards the waste inlet. Shifts in the species percentages towards the emission source, a high percentage of taxa with large conductivity tolerances, the presence of a small Achnanthes minutissima Kützing morphotype, and occurrences of taxa focused at habitats of higher electrolyte content, indicate subtle impacts on the epilithic diatom flora. An analysis of the seasonal succession of the epilithic diatoms at the waste inlet compared to a lake intern reference site, reveals that only during the late summer period in 1998 the diatom assemblage at the waste inlet became significantly different, indicating seasonally restricted effects of the industrial emissions.     

Interannual Changes in the C:N:P Ratios of Seston and Zooplankton of a High Mountain Lake in Sierra Nevada,Spain

We investigated the carbon, nitrogen and phosphorus content inthe seston and the zooplankton of a high-mountain lake duringthree years of contrasting physical and chemical conditions.Carbon in seston was ten times higher in 1995 than in 1996 and1997. Phosphorus content in seston was variable for the studyperiod, increasing gradually towards late summer in 1995, butpeaking abruptly in 1996 and 1997, reflecting atmosphericdepositions. Seston C:P were high and did not fit any definitepattern in 1995, and were particularly low after the thaw, increasing towards mid-summer in 1996 and 1997. As the seasonprogressed, major decreases in these ratios occurred coincidingwith important atmospheric inputs in the lake area. ZooplanktonN:P and C:P were negatively associated to the appearance ofrotifers and copepod nauplii in 1995, but positively correlatedto the ontogenetic development of the most abundant species,Mixodiaptomus laciniatus, in 1996. Seasonal variations inzooplankton N:P and C:P ratios showed limited interannual, butlarge intraannual variability. The comparison between the bulkcarbon in seston and zooplankton demands for this elementindicated that zooplankton were above food-quantity thresholdsfor maximum growth in 1995, 1996 and mid-season of 1997,therefore suffering only from food-quantity constraints afterthe thaw (nauplii dominance) and towards late season (adultdominance) in the latter year. The high C:P ratios in sestonrelative to zooplankton in 1995 imply that the zooplankton mayhave faced severe food-quality constraints (in terms ofphosphorus) during this year. Differences between bulkzooplankton and seston elemental nutrients are also discussed inrelation to the competitive abilities of species, andparticularly of Daphnia.     

The Effect of Sediment Source Changes on Pollen Records in Lake Sediments

A major focus of palynological research has been to assess the various pathways by which pollen is delivered to sedimentary archives. In open lake systems, the contribution of streamborne pollen to lake sediments is thought to be highly significant. Despite this, little research has attempted to identify changes in the pollen record that might be attributed to changing sediment pathways rather than to changes in vegetation. This research aims to partially redress this gap by examining a dated pollen sequence from Kyre Pool, Worcestershire, England. The results presented in this paper suggest that some changes in sediment source, as determined by a fingerprinting approach, can influence the pollen record reconstructed from a lake sediment profile.     

Temporal Trends in Mercury Accumulation in Lake Sediments in Sweden

Lake sediment cores were analyzedto study the history of mercury (Hg) pollution andparticularly to determine whether recent sedimentconcentrations have declined in response todeclining atmospheric deposition of Hg. Sedimentcores from 6 forest lakes distributed fromsouthern to northern Sweden and 3 northernmountain lakes were analyzed for Hg using CVAAS. A400 cm sediment profile from Måkevatten insouthwest Sweden indicates that the onset of Hgpollution occurred in the 18th century. Anindisputable increase in Hg concentrationsoccurred concurrent with the appearance ofspheroidal carbonaceous flyash particles (SCP)derived from fossil-fuel combustion, in themid-19th century. There is a strong correlationbetween Hg and SCP concentrations in the sedimentcores (r=0.67 to 0.91), which suggests a strongrelationship between historical Hg pollution andfossil fuel burning. In contrast to sediment corestaken in 1979, maximum Hg concentrations are nowobserved below the sediment surface and declinetowards the sediment surface. This study confirmsthat reductions in atmospheric deposition of Hgover Sweden have resulted in a decreased transferof total Hg to aquatic environments as reflectedby lake sediments, and that lake sediment profilesof Hg concentrations reflect relative trends inthe atmospheric deposition of Hg rather thanpost-depositional diagenetic processes.     

Nutrient export and material recycling using aquatic plants: Lake Kitagata case study

Lake Kitagata in Fukui Prefecture, Japan, was examined to collect fundamental data on nutrient export and material recycling using the native aquatic plants, common reed and wild rice. Common reed was located all over the lake shore, while wild rice was in the upper part of the lake. On average, the nutrient content was nitrogen: 2.1 and 2.6?%, P₂O₅: 0.38 and 0.64?%, K₂O: 2.1 and 2.4?% for common reed and wild rice, respectively, and decreased along with their growth. If harvested in October, the nitrogen and phosphorus exported from the lake were estimated to be only 1.1 and 1.9?% of the inflow, respectively. Methane fermentation of these plants showed an average of 134 and 150?mL-CH₄/g-VS added for common reed and wild rice, respectively, indicating possible use as an auxiliary source. The composting of these plants mixed with chicken manure, bean curd and rice bran was successful, and the products were rich in the major nutrients and well-balanced. A pretreatment method combining sulfuric acid and thermal treatment was able to convert about 50?% of cellulose in common reed to glucose, the precursor for bioethanol production. Therefore, these technologies are demonstrated to be helpful for the beneficial use of the biomass.     

Application of Static Critical Load Models for Acidity to High Mountain Lakes in Europe

Critical load models for acidityprovide a measure of the sensitivity of surfacewaters to acid deposition, and can be used todetermine critical load exceedance and potentiallong-term harmful effects. Three static models,the Steady-State Water Chemistry model, diatommodel and First-order Acidity Balance model, arehere applied to 11 high mountain lakes in Norway,Scotland, the Alps, the Pyrenees and the Tatras.Between five and seven of the lakes show criticalload exceedance, depending on the model used.Nitrogen as well as sulphur deposition isimportant in causing exceedance. Since soil andvegetation cover are generally sparse, geologyand lake retention time appear to be key factorsin the determination of critical load. Retentionof nitrogen is observed, but it is unclearwhether this occurs within the lake or theterrestrial part of the catchment.     

Study of Pollution of the Plitvice Lakes by Water and Sediment Analyses

The process of eutrophication in form of intense plant growth has been observed in some lakes and water streams at the Plitvice Lakes National Park in central Croatia. Here we investigate whether this phenomenon is a consequence of anthropogenic pollution or due to naturally produced organic matter in the lakes. We applied chemical analysis of water at two springs and four lakes (nutrients, dissolved organic carbon (DOC), trace elements) and measurements of surface lake sediments (mineral and organic fraction analyses, trace elements) in four different lakes/five sites. The chemical composition of water does not indicate recent anthropogenic pollution of water because the concentrations of most trace elements are below detection limits. The concentrations of DOC and nutrients are slightly higher in the area of increased eutrophication-plant growth. Also the content of organic matter in the sediment is at the highest level in areas with highest C/N ratio indicating that the organic fraction of this sediment is mainly of terrestrial origin. There is no significant difference among the trace element concentration in the upper segment of all cores, deposited approximately during last 50 years when higher anthropogenic influence is expected due to development and touristic activity, and the lower part of the cores, corresponding to the period approximately 100–200 years before present. The content of trace elements and organic matter in sediments decreases from the uppermost lake downstream. According to our results there is no indication of recent anthropogenic pollution in water and sediment. Higher concentrations of DOC in water as well as phosphorus and some other elements in the lake sediment can be a consequence of input of natural organic matter to the lake water.     

Composite Biofilms grown in Acidic Mining Lakes and assessed by Electron Microscopy and Molecular Techniques

Microbial consortia of composite biofilms, grown in surface water of acidicmining lakes near Lauchhammer, Germany, were investigated. The red-brown colored lake water was acidic (pH 2.5), had high concentrations of Fe(III), Al(III), and sulphate and low concentrations of dissolved organic matter. As a result the abundance of bacteria in the lake is with 10⁴ cells mL^-1 rather low. One input of organic material into the lake are autumnal leaves from trees, growing in the lakeside area. From aliquots of unfixed birch leave biofilms the 16S rRNA genes were amplified by PCR and community fingerprints were determined by single-strand conformation polymorphism (SSCP) analysis. Specific bands within the fingerprints were extracted from SSCP gels and sequenced for the taxonomical affiliation.These results were compared with those from the second type of biofilms which were grown on sterile substrata, floating submersed in surface waters of the lakes. By excising the bands from the gel and sequencing the individual bands bacterial taxa, common to both types of biofilms, were found but also some, which were only present in one type of biofilm. Ultrathin sectioned biofilms often showed bacteria associated with electron dense particles as main inorganic constituents. Elemental microanalysis by energy dispersive X-ray analysis (EDX) revealed them to contain iron, sulfur and oxygen as main elemental fractions and electron diffraction ring pattern analysis classified them to be schwertmannite. These bacteria and their interactions with each other as well as with the inorganic minerals formed in this lake generally is of great interest, in order to use these results for bioremediation applications.     

Tracking of release and remediation progress from large pipeline break east of Dallas,Texas: Protection of Lake Tawakoni water supply

A gasoline pipeline owned by Explorer Pipeline Company ruptured leaking methyl tertiary butyl ether (MTBE), a gasoline additive, into a creek and lake that the city of Dallas used as a water source. Because of the contamination, the city had to build a pipeline (nine feet in diameter, over two and three‐quarters of a mile in length, and built in three months) to another lake, at a cost of about $9 million. The volume of the release was estimated at 1.7 million gallons of gasoline containing MTBE at 9 percent per volume. Thousands of soil, water, and groundwater samples were taken to track the MTBE plume as it migrated from the spill site, through almost 30 miles of creek and throughout a lake containing 700,000 acre‐feet (228 billion gallons) of water. Four years after the spill, MTBE remains throughout the groundwater system, primarily in the drainage basin along the almost 30 miles of creek. This article focuses on the detailed tracking of all sampling data and the impact that the ongoing threat of MTBE contamination had on the water supplier. © 2006 Wiley Periodicals, Inc.     

Deposition and Storage of Spheroidal Carbonaceous Fly-Ash Particles in European Mountain Lake Sediments and Catchment Soils

Spheroidal carbonaceous particles(SCPs) are produced only from high temperaturecombustion of fossil-fuels. In mountain lakesystems, they provide an unambiguous indicator ofatmospheric deposition. In order to comparedepositional fluxes of SCPs between mountainareas experiencing various pollutant regimes,intensive bulk deposition sampling was undertakenat five sites across Europe. Catchment soil coresand lake sediment cores were also taken at eachsite to compare SCP storage over the post-industrial period. Atmospheric, sediment and soilSCP data showed similar patterns. Highestcontamination was found in Scotland, Slovakia andSpain with the Austrian site intermediate and themid-Norwegian site least contaminated. A highproportion of accumulated SCPs were found to bestored in catchment soils at each site.Therefore, a significant increase in soilerosion, possibly as a result of future climatechange, could lead to the input of largequantities of catchment stored SCPs and, byimplication, other atmospherically depositedcontaminants to the lake ecosystem.     

水利水电建设中河流生态用水理论与方法研究

国内外研究表明,除了水质,生态用水也是维持生态系统健康发展的重要因素。因此,在水资源配置中保证一定量的生态用水是保护生态环境的重要措施。生态用水具有时空尺度和阈值范围,而人类大规模的水电开发则会造成其时空尺度的改变,甚至生态阈限难以被满足。统计数字表明,近5年来我国新建水电站下泄生态流量的不满足率达到57％。我国目前急需考虑的生态用水政策是：尽快建立河流最小生态流量的相关标准,制定河流生态用水配套法律法规;同时,通过跨流域调水等水段,加强生态环境需水的宏观调控。建议最小生态用水量不应小于工程所在河流控制断面多年平均流量的10％,当多年平均流量大于80m^3／s时不小于5％;同时根据河流的不同生态环境功能,应积极开展多方法、多方案比选。     

Analysis of land suitability for the siting of inter-municipal landfills in the Cuitzeo Lake Basin, Mexico

This paper presents three spatial decision-support models (Boolean logic, binary evidence and overlapping index of multiple class maps) to perform a land suitability analysis for sanitary landfill siting. The study was carried out in the basin of Lake Cuitzeo, Mexico, with the objective of locating areas that comply with environmental regulations and with the inter-municipality criterion, i.e., that are accessible by at least two municipalities. Biophysical and socio-economic data were processed in a Geographic Information System (GIS). The three models differ in their complexity and restrictiveness. The Boolean logic model is easier to apply and more restrictive than the other two, because it is based on the assessment of single attributes. On the other hand, the binary data and overlapping index methods are relatively more complex because they require attribute weighting. The results showed that 23 of the 28 municipalities included in the basin have at least one area that was classified as highly suitable. The most suitable areas covered from 63.8 to 204.5 km(2) (from 1.5% to 5%), and they are not distributed homogeneously, but clustered around four main sites. The larger and most suitable of these sites is located in the central part of the basin, and it can be accessed by five of the most densely populated municipalities. The proposed approach represents a low-cost alternative to support a common spatial decision-making process in developing countries.     

Distribution of Redox-sensitive Elements in Bottom Waters,Porewaters and Sediments of Rogoznica Lake (Croatia) in Both Oxic and Anoxic Conditions

Geochemical, mineralogical and sedimentological analyses were carried out to contrast two different sites (respectively characterized by permanently oxic and anoxic conditions) in a small, meromictic, seawater lake. In fact, due to relatively high organic matter content, and reduced water exchange, the Rogoznica Lake has almost permanent anoxic conditions below the depth of 12 m, where sediment can be considered an anoxic–sulphidic sedimentary environment. Different water column and sediments redox conditions affect the distribution and speciation of major redox-sensitive metals (Fe, Mn, Mo), reduced sulphur species (RSS) and dissolved organic C (DOC). Trace metals, especially those that accumulate in anoxic–sulphidic environments (Fe, Mo) showed a marked enrichment in the solid phase, whereas the low solubility of sulphides leads to low porewater concentrations. The relatively high sedimentary enrichment of Mo (up to 81 mg/kg) also confirms highly anoxic conditions within the Rogoznica Lake sediments. Results clearly show that chemical species within the sediments will tend towards equilibrium between porewater and solid phase according the prevailing environment conditions such as redox, pH, salinity, DOC.