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1
MIHAIESCU, Tania, Manuela CUC e Mihnea Andrei MIHAIESCU. "The Salty Lakes of Ocna Sibiului. Past. Present. Future". Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture 70, n. 2 (25 novembre 2013): 377–82. http://dx.doi.org/10.15835/buasvmcn-agr:9758.
Testo completoAbstract (sommario):
At the center of the Transyvanian Plateau lies Ocna Sibiului, with its salt deposits which, in places, run up to one thousand meters below the surface. The presence of these deposits has been favored, due the extraction of salt throughout the years causing the formation of the now famous salt lakes. Due to different environmental conditions, lacustrine cuvettes and water quality differ from one lake to another. The studied lakes are considered to be in conection with the salt deposits exposed through minig activities carried on in different time periods. Other lakes in the area already are isolated from salt deposits due to natural sedimentation proceses. The study adresses the lakes which still present a high degree of salinity and are used for balnear purposes, and present, due to various factors, variation of physical-chemical composition throughout the year. Water samples were collected from the main six lakes in Ocna Sibiului (Ocniţa - Avram Iancu; Rândunica; Negru; Fără Fund; Brâncoveanu and Gura Minei). Surveys were carried out in four periods (March-November) during 2012.Water temperature, electrical conductivity (at 25°C) and pH were measured in-situ. The water pH changed from a lake to another. Generally it is within the range of 6.78 to 8.8 highlighting the neutral to slightly alkaline lake water. Salt lake water conductivity values, in the upper layers vary within a wide range, from more than 200 mS cm-1 to 45.7 mS cm-1, with different values from the different lacustrine units. The salt water lakes are characterized by high content of sodium and chlorine ions. The other major ions are present in a small amount. This paper aims to compare the past and present evolution, characteristics and environment of these lakes, , and, based on this and current research, to project a vision of their future and how it will affect the lives of future generations living besides them.
2
Du, Baolong, Liping Zhu, Jianting Ju, Junbo Wang, Qingfeng Ma e Qiangqiang Kou. "A Quantification of Heat Storage Change-Based Evaporation Behavior in Middle–Large-Sized Lakes in the Inland of the Tibetan Plateau and Their Temporal and Spatial Variations". Remote Sensing 15, n. 14 (8 luglio 2023): 3460. http://dx.doi.org/10.3390/rs15143460.
Testo completoAbstract (sommario):
A large number of different-sized lakes exist in the inland area of the Tibetan Plateau (TP), which are examples of the important connection between the atmosphere and hydrosphere through the analysis of lake surface convergence and evaporation processes. The evaporation level changes that occur in middle–large-sized lakes (surface area > 50 km2) in the area directly influence the regional mass and energy balance values, atmospheric boundary layer heat and humidity structures, and weather processes occurring in the lower-reach areas. The studies conducted in the literature at present, concerning lake evaporation processes, generally overlook the differences in lake heat storage behavior due to the reduced amount of data in the literature concerning lake bathymetry. According to the in situ bathymetric data obtained for 68 middle–large-sized lakes in the inner basin of the TP, in this study, we calculated their heat storage (G) change values by using the different vertical-depth water-temperature-change integral method, and we established a regression equation for the heat storage and lake surface net radiation values for 68 lakes. The evaporation rates of 134 middle–large-sized lakes larger than 50 km2 in the inland are of the TP were calculated by obtaining the G regression result and adopting it into the Penman model, as well as estimating the evaporation losses of theses 134 lakes from 2002 to 2018. The result shows that the annual average evaporation rate for these lakes is 927.39 mm/year, with an insignificant upward trend (0.10 mm/year). This method achieved good accuracy compared with the Bowen ratio method, which estimates the evaporation rate during the ice-free season, with a high correlation coefficient (R) value of 0.95 and least root mean square error (RMSE) value of 61 mm. The annual mean evaporation rate can be divided into the southern and northern lake groups along a 34°N line with a difference of 314.41 mm/year. The annual average evaporation volume of these lakes was 25.02 km3 and showed an upward trend of 0.35 km3/year. Among them, the annual average evaporation volume contribution ratio of level-1 lakes (50 km2 ≤ lake’s area < 100 km2, 61 lakes) was 14.04%, showing an upward trend, and the contribution of level-3 lakes (lake’s area ≥ 500 km2, 10 lakes) was 41.50%, showing a downward trend. There were no obvious changes in the level-2 lakes (100 km2 ≤ lake’s area < 500 km2, 63 lakes), which maintained at the same level in approximately 44.46%. Air temperature is the most important factor affecting the evaporation rate of lakes, while the lake surface area is the main factor affecting lake evaporation volume. Our study, considering the actual lake heat storage value, provides a useful reference for further improving lake water budget balance values and watershed hydrologic features in the inland closed lakes located in the TP.
3
Ogutu-Ohwayo, Richard, e R. E. Hecky. "Fish Introductions in Africa and Some of Their implications". Canadian Journal of Fisheries and Aquatic Sciences 48, S1 (19 dicembre 1991): 8–12. http://dx.doi.org/10.1139/f91-299.
Testo completoAbstract (sommario):
Fish introductions in Africa have been made at various spatial scales from small fish ponds to the largest lakes, primarily to sustain or increase production, though some were to develop sport fisheries and to control unwanted organisms. Some introductions have fulfilled their objective in the short term, but several "successful" introductions have created uncertainties about their long-term sustainability. Lates niloticus, Oreochromis niloticus, O. leucostictus, Tilapia melanopleura and T. zilli were introduced into Lakes Victoria and Kyoga in 1950's and early 1960's; by the 1980's L. niloticus and O. niloticus dominated the fisheries, having virtually eliminated a number of endemic species. In Lake Victoria, the loss of genetic diversity has been accompanied by a loss of trophic diversity; the transformation of the fish community coincided with profound eutrophication (algal blooms, fish kills, hypolimnetic anoxia) which might be related to alterations of the lake's food-web structure. By contrast, the introduction of a planktivore, Limnothrissa miodon into Lake Kivu and the Kariba reservoir has established highly successful fisheries with little effect on the pre-existing fish community or trophic ecology. The endemic species-rich African Great Lakes may be particularly sensitive to introductions. Species extinctions, introgressive hybridization and ecosystem alterations may occur following introductions.
4
Pan, Bao Yuan, Guo Ting Yang, Yun Ma e Yi Bin Ren. "Countermeasure and Research of Jingbo Lake Water Environment Rehabilitation". Advanced Materials Research 518-523 (maggio 2012): 164–67. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.164.
Testo completoAbstract (sommario):
China is a country with a large lakes, with the development of social economy, the water pollution of lakes is more serious, lake’s eutrophication has become the major environmental problems of the China's lakes and reservoirs. This document explains through the investigation and evaluation environment to analyze the current situation and the pollution of Jingbo Lake, and puts forward countermeasures and pollution control environmental protection measures for management of Jingbo Lake, develop and provide technical reference of Jingbo Lake.
5
Carignan, Richard, Pierre D'Arcy e Sébastien Lamontagne. "Comparative impacts of fire and forest harvesting on water quality in Boreal Shield lakes". Canadian Journal of Fisheries and Aquatic Sciences 57, S2 (7 settembre 2000): 105–17. http://dx.doi.org/10.1139/f00-125.
Testo completoAbstract (sommario):
Water quality was monitored in Boreal Shield lakes for 3 years following their simultaneous impact by clearcut logging or wildfire. Seventeen similar undisturbed lakes served as references. Dissolved organic carbon (DOC) and the light attenuation coefficient (εPAR) were up to threefold higher in cut lakes than in reference and burnt lakes. Compared with median values for reference lakes, cut and burnt lakes had higher concentrations of total phosphorus (TP) (two- to three-fold), total organic nitrogen (TON) (twofold), and K+, Cl-, and Ca2+ (up to sixfold). NO3- and SO42- concentrations were up to 60- and 6-fold higher, respectively, in burnt lakes than in reference and cut lakes. In most cases, impacts were directly proportional to the area harvested or burnt divided by the lake's volume or area. These simple models correctly predicted the changes observed in three lakes harvested during the study. Some of the ob served effects occur on different time scales. Mobile ions released by fire (K+, Cl-, SO42-, NO3-) or harvesting (K+, Cl-, some DOC) are rapidly flushed out of the watershed (50% decrease in 3 years). Other constituents or properties (TP, TON, DOC, εPAR, Ca2+, Mg2+) show little change or are still increasing after 3 years and will take a longer time to reach normal levels.
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Henny, C., T. Suryono, D. Rohaningsih, GP Yoga, J. Sudarso e A. Waluyo. "The occurrence of microplastics in the surface water of several urban lakes in the Megacity of Jakarta". IOP Conference Series: Earth and Environmental Science 1201, n. 1 (1 giugno 2023): 012023. http://dx.doi.org/10.1088/1755-1315/1201/1/012023.
Testo completoAbstract (sommario):
Abstract Microplastic pollution in the marine and freshwater environment has been a global concern. The pollution in densely populated urban areas may be more severe than in any other environment, especially in areas lacking plastic waste management. Urban lakes in the Megacity of Jakarta, the capital city of Indonesia, and neighboring areas, which is the most populated city in the world, have been severely polluted by plastic waste. The urban lakes studied were located downstream of watershed areas of major rivers that outflow into Jakarta Bay, the Java Sea, and finally the ocean. To our knowledge, no studies have been reported on microplastic pollution in urban lakes in the Megacity of Jakarta. This study investigated the first occurrence of microplastics in the surface water of six urban lakes in the Megacity of Jakarta. Grab water samples were collected in either inlet or outlet areas of lakes. The water samples were pretreated and sieved to separate the microplastics. The quantification and the identification of microplastics were made using a Stereo Microscope. The most downstream urban lakes in the densely populated area close to Jakarta Bay, which is the final disposal of plastic wastes from the river canal and runoff from the surrounding area, had more microplastics than the urban lakes in the area with less population and further from the Bay. The most abundant microplastics found in the lake’s surface water was about 30,000 particles/m3, whereas 300 - 500 µm and the foam were the dominant size and type of microplastics discovered. The concern is that the smallest size of particles of microplastics found in the lake’s water could potentially contaminate aquatic biota, especially fish, not only in the lakes but also in Jakarta Bay, where fishing activities are substantial.
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Brillo, Bing Baltazar C. "Government, Premier Leader and Small Lakes’ People Vis-a-Vis Lake Governance". Social Sciences 11, n. 4 (6 aprile 2022): 165. http://dx.doi.org/10.3390/socsci11040165.
Testo completoAbstract (sommario):
Small lakes within social sciences’ conceptualisation are mostly wanting, less anchored and seldom scrutinised in academic literature as opposed to large lakes and natural sciences. Essentially, small lakes, from a social sciences’ perspective, are about people connecting and enhancing through lake governance. Thus, the main argument is that a small lake’s people must accept, broaden and elevate the prospect of lake governance by focusing on and embracing the central concepts of government—the most compulsory and crucial constituent—as well as premier leader—the most pre-eminent and imperative function. Accordingly, lake governance refers to engaging with and intervening in the collective people of a small lake, to undertake economic development, pursue ecological conservation and manage government. Government refers to steering a small lake’s people towards emphasising executive authority and decision-making power, whether through solutions, policies, regulations and/or implementations. The premier leader refers to the person presiding over a small lake’s people in the critical aspects of resoluteness—in establishing and sustaining the rules—and decisiveness—in settling and determining a community’s issues. Overall, as small lakes’ people are political, lake governance is consequential, and a government/premier leader is evidently the most efficacious outcome, whether for addressing problems, choosing decisions or ameliorating society.
8
Rup, Michael P., Sarah A. Bailey, Chris J. Wiley, Mark S. Minton, A. Whitman Miller, Gregory M. Ruiz e Hugh J. MacIsaac. "Domestic ballast operations on the Great Lakes: potential importance of Lakers as a vector for introduction and spread of nonindigenous species". Canadian Journal of Fisheries and Aquatic Sciences 67, n. 2 (febbraio 2010): 256–68. http://dx.doi.org/10.1139/f09-180.
Testo completoAbstract (sommario):
Ballast water is recognized globally as a major vector of aquatic nonindigenous species (NIS) introductions; domestic ballast water transfers, however, have generally been considered low risk in North America. We characterize ballast operations of domestic ships in the Great Lakes – St. Lawrence River system (Lakers) during 2005–2007 to examine the risk of primary and secondary introductions associated with ballast water transfers over short distances. Results indicate that Lakers transported at least 68 million tonnes of ballast water annually. Approximately 71% of ballast water transfers were interregional, with net movement being from lower to upper lakes. A small proportion of ballast water discharged in the Great Lakes (<1%) originated from ports in the St. Lawrence River that may serve as sources for new NIS. These results indicate that domestic ballast water transfers may contribute to NIS introductions and are likely the most important ballast-mediated pathway of secondary spread within the Great Lakes. Future efforts to reduce invasion impacts should consider both primary and secondary introduction mechanisms.
9
Alvo, Robert. "Common Loon, Gavia immer, Breeding Success in Relation to Lake pH and Lake Size Over 25 Years". Canadian Field-Naturalist 123, n. 2 (1 aprile 2009): 146. http://dx.doi.org/10.22621/cfn.v123i2.693.
Testo completoAbstract (sommario):
I monitored Common Loon (Gavia immer) breeding success in relation to lake pH (range 4.0–8.5) between 1982 and 2007 on 38 single-pair lakes (5–88 ha) in the Sudbury, Ontario, area. No chicks fledged on lakes with pH < 4.4. Chicks fledged on lakes with slightly higher pH only if the lakes were relatively large. Acidic lakes became less acidic as sulphur dioxide emissions from the Sudbury smelters and sulphur deposition from other long-range sources decreased. Two lakes initially too acidic to support successful loon reproduction eventually had successful reproduction. One loon pair used two large acidic lakes (combined area 140 ha) connected by shallow rapids, and one of the adults made extremely long dives (average = 99 s) while foraging for the chicks. One chick died on that lake after apparently ingesting a very large food item; the lack of smaller items was attributed to the lake’s acidity. My results suggest that a shortage of food for chicks is the main reason why low pH reduces breeding success. I suggest that, for lakes without high levels of dissolved organic carbon (DOC), the critical pH for loon breeding success is approximately 4.3, and the suboptimal pH is approximately 4.4–6.0.
10
Thakuri, Sudeep, Basudev Neupane e Nitesh Khadka. "Conservation of Gosainkunda and Associated Lakes: Morphological, Hydrochemistry, and Cultural Perspectives". Journal of Tourism and Himalayan Adventures 3, n. 1 (19 agosto 2021): 74–84. http://dx.doi.org/10.3126/jtha.v3i1.39119.
Testo completoAbstract (sommario):
In this paper, we present the current situation of the Gosainkunda and associated lakes based on the preparation of an inventory of lakes using the Google Earth Engine and 2020 Sentinel 2A satellite imagery. Furthermore, we discuss the hydrology, hydrochemistry, and cultural significance of the lakes based on the systematic review of available literatures. In 2020, there are 22 lakes along with Gosaikunda (12.7±0.4 ha) in the Upper Trishuli watershed (59.2 km2), extending from 1274 to 4993 m elevation and covering a total area of 80 ha. The largest lake is Bhairabkunda, with an area of 15.5±0.5 ha. The water bodies in the region are drying, and some of the lakes have already disappeared from the region. But some lakes in the region are evolving as temporary water bodies. The high-altitude lakes are sensitive indicators of anthropogenic disturbance and changing climate. Though the lakes have better hydrochemical quality than the urban lakes located in the southern part of the country, the evidence shows increasing local and long-range transport and deposition of the pollutants in the lake water. The presence of chemical constituents of anthropogenic sources in the water of oligotrophic lakes is possibly evidence of the long-range transport of pollutants. Considering the cultural importance of the region, the number of visitors is increasing annually. Increasing human activities in and around the lake, long-range transport of pollutants, and changing environment in the area are demanding for the lake's conservation. We suggest regular monitoring of the high-altitude lakes to understand the ongoing climate change and anthropogenic impacts.
11
Fauzi, M., A. Hendrizal e B. Amin. "Morphometric Surface Dimension Analysis of Three Different Oxbow Lakes in Lubuk Siam Village". IOP Conference Series: Earth and Environmental Science 1118, n. 1 (1 dicembre 2022): 012045. http://dx.doi.org/10.1088/1755-1315/1118/1/012045.
Testo completoAbstract (sommario):
Abstract Oxbow lake is usually formed in a meandering river. Lubuk Siam village is one of the places passed by the Kampar River, which has a meander shape. In this study, there are three oxbow lakes to be studied: Lubuk Siam, Selat Panjang, and Putus. Morphometric Surface Dimension data was collected by using geographical information system (GIS). It was then analyzed using GIS data processing software. The results showed that Lake Putus has the most significant area compared to the other two lakes adjacent to each other. The size of Lake Putus is 22.99 Ha. The results showed that three of these lakes’ shoreline development index (SDI) value is less than 1. This SDI value shows that the shape of the lake is regular. The lake’s regular shape indicates the lake’s low productivity as a result of a low number of nutrient inputs.
12
Dickman, M. D. "Evidence of Recent Eutrophication of an Urban Lake in Nanjing, China". Water Quality Research Journal 27, n. 2 (1 maggio 1992): 311–26. http://dx.doi.org/10.2166/wqrj.1992.022.
Testo completoAbstract (sommario):
Abstract There is very little known about urban lakes in China, and for this reason this paper provides a synthesis of palaeolimnological and past and present phytoplankton studies of Xuanwu Lake, an urban lake near the center of Nanjing, in Jiangsu Province, China. Documented changes in biotic species diversity and water chemistry in this urban lake over the last thirty years have been attributed to progressive eutrophication associated with lake in-filling, commercial harvesting of plants and fish and intense industrial and urban activities within the lake's watershed. During the last decade, phytoplankton biomass in Xuanwu Lake has increased ten fold. This has resulted in a steady shallowing of the lake's photic zone to a depth of less than 0.7 m with Secchi transparencies of 0.3 to 0.4 m. Wind-generated currents prevent anoxia from occurring in this shallow wind-swept lake no matter how eutrophic the lake. As a result, many of the negative impacts of hypertrophication, such as anoxia, fish kills and noxious odors, are avoided. Thus, shallow lakes like Xuanwu Lake can become eutrophic without producing long periods of hypolimnetic anoxia such as those frequently reported for deeper eutrophic lakes. It was concluded that it is important to treat deep urban lakes differently from shallow urban lakes as the latter systems rarely display extended periods of anoxia, fish kills and noxious odors.
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Boreux, Maxime P., Scott F. Lamoureux e Brian F. Cumming. "Use of water isotopes and chemistry to infer the type and degree of exchange between groundwater and lakes in an esker complex of northeastern Ontario, Canada". Hydrology and Earth System Sciences 25, n. 12 (13 dicembre 2021): 6309–32. http://dx.doi.org/10.5194/hess-25-6309-2021.
Testo completoAbstract (sommario):
Abstract. While interactions between groundwater and lake-water influence water chemistry, water balance, aquatic organisms, biochemical cycles and contamination levels, they remain a poorly studied component of lake hydrology. Identifying the controls of groundwater and lake-water interactions at the landscape level and classifying lakes into categories based on their degree of interaction with the groundwater can provide insights into a lake's sensitivity and vulnerability to environmental stressors. Such information can also provide baseline conditions for comparison to future changes that are important for water management and conservation. To this end, water chemistry and water isotopic composition were investigated in a set of 50 boreal lakes located at different elevations in an esker system near Timmins, Ontario. Analyses focused on stable isotopic ratios of hydrogen and oxygen and specific conductance as indicators of the position of a lake with respect to the influence of groundwater. Both isotopic composition and specific conductance distinguished higher-elevation groundwater-recharge lakes from lower-elevation groundwater-discharge lakes. Groundwater-recharge lakes were high-elevation lakes characterized by enriched isotopic values and low values of specific conductance. In contrast, groundwater-discharge lakes were isotopically depleted and had higher values of specific conductance and occurred at lower elevations. An intermediate group of lakes was also defined (termed seepage lakes) and had intermediate isotopic and water-chemistry characteristics compared to recharge and discharge lakes. Differences in water geochemistry between field campaigns revealed that upland groundwater-recharge lakes showed evidence of evaporative drawdown, indicating sensitivity to short-term changes in climate, whereas the lower-elevation groundwater-discharge lakes showed little variation between seasonal samples and consequently would likely be affected only by hydroclimatological changes of greater duration and magnitude.
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PURBA, GANDI Y. S., EKO HARYONO, SUNARTO SUNARTO, JEMMY MANAN, LUKAS RUMENTA, PURWANTO PURWANTO e LEONTINE E. BECKING. "Jellyfish Lakes at Misool Islands, Raja Ampat, West Papua, Indonesia". Biodiversitas Journal of Biological Diversity 19, n. 1 (1 gennaio 2018): 172–82. http://dx.doi.org/10.13057/biodiv/d190124.
Testo completoAbstract (sommario):
Purba GYS, Haryono E, Sunarto, Manan J, Rumenta L, Purwanto, Becking LE. 2018. Jellyfish Lakes at Misool Islands, Raja Ampat, West Papua, Indonesia. Biodiversitas 19: 172-182. Misool Islands, located in southern Raja Ampat in West Papua, has dozens of anchihaline lakes (marine lakes). Three of these lakes, Lenmakana, Karawapop, and Keramat, house populations of jellyfish. This study mapped and described the characteristics of the three ‘jellyfish lakes’ during field surveys in October 2015 and May 2016. The lakes ranged in area from 0.5−3.2 hectares. All three lakes harbored Mastigias papua, Lenmakana and Keramat lakes also harbored Aurelia sp., and Keramat had a third jellyfish species Cassiopea ornata. However, at Karawapop the jellyfish were not found on the water surface during the first round of field work because of effects associated with the El Niño phenomenon at that time. As a result of the El Niño effect, at Keramat, brown Mastigias became white in May 2016. The three lakes have different tidal delays (30−120 min) and dampened tidal amplitude (62%) compared to the sea. The benthos was found to be dominated by bivalves (Brachidontes sp.), algae (Cladophora sp., or Halimeda sp.) and sponges (predominantly Haliclona spp. and Tethya spp.). In addition, species of the family Synaptidae (Holothuroidea) were abundant and spread over almost all the bottom of Karawapop Lake, while tube-worms of the Polychaeta class were identified in Keramat Lake. Although these lakes are identified as a conservation area, currently there is no management activity in Lenmakana and Karawapop Lakes, despite the fact that the lakes are growing in popularity as a tourist site. Our paper provides the baseline data for future conservation efforts.
15
Polykarpou, Polina, Matina Katsiapi, Savvas Genitsaris, Natassa Stefanidou, Gerald Dörflinger, Maria Moustaka-Gouni, Athena Economou-Amilli e Dionysios E. Raitsos. "Phytoplankton Diversity and Blooms in Ephemeral Saline Lakes of Cyprus". Diversity 15, n. 12 (7 dicembre 2023): 1204. http://dx.doi.org/10.3390/d15121204.
Testo completoAbstract (sommario):
The ephemeral saline lakes of Cyprus in the Mediterranean, situated in close proximity to each other, demonstrate pronounced seasonal and interannual fluctuations in their environmental conditions. Despite their extreme saline conditions, these lakes support phytoplankton diversity and bloom-forming species. Anthropogenic activities, particularly urban and artificial land uses within their catchments, contribute to eutrophication, warranting conservation attention within the context of European legislation. Over two years (2018–2019), we examined phytoplankton abundance and diversity alongside salinity in six lakes, with samples collected every three weeks. Chlorophytes were the dominant and most diverse group, followed by cyanobacteria and diatoms. Increasing salinity correlated with reduced compositional diversity and species richness. The proximity of lakes to each other suggested airborne microbe colonization from one lake to another as a significant factor in shaping these communities, while similar land use within each lake’s catchment impacted bloom formation. The highly halotolerant chlorophyte Dunaliella frequently dominated phytoplankton blooms, occasionally coexisting with other taxa in less saline lakes. Our findings provide insight into the phytoplankton community dynamics in temporal saline lakes, essential for developing effective conservation strategies and sustainable management practices.
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Bernhardt, E. S. "Cleaner Lakes Are Dirtier Lakes". Science 342, n. 6155 (10 ottobre 2013): 205–6. http://dx.doi.org/10.1126/science.1245279.
Testo completo
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Bowling, LC. "Heat contents, thermal stabilities and Birgean wind work in Dystrophic Tasmanian Lakes and Reservoirs". Marine and Freshwater Research 41, n. 3 (1990): 429. http://dx.doi.org/10.1071/mf9900429.
Testo completoAbstract (sommario):
Values of whole-lake standard energy parameters (heat content, thermal stability and Birge's work of the wind) for ten dystrophic standing waters from western Tasmania were lower than expected for lakes of their depth and area. Although controlled principally by morphometric factors, the degree of shelter from wind and the extent of each lake's dystrophy also had considerable effects. These factors allowed only surface waters to contribute to the annual heat exchange cycle, thereby reducing the magnitude of each lake's heat budgets and influencing stability and wind work values. The lakes show considerable short- and long-term fluctuations in heat content, stability and wind work values in response to the capricious maritime meteorological conditions of the area. However, long periods between successive samplings may have caused some underestimation of the ranges of these three parameters. Despite this, the study reveals that these standard energy parameters are effective in describing the annual energy input and resistance to wind-induced mixing of these dystrophic Tasmanian lakes.
18
Hrdinka, Tomáš, e Miroslav Šobr. "Manifestations and causes of meromixis in lakes resulting from mineral extraction in Czechia". Geografie 115, n. 1 (2010): 96–112. http://dx.doi.org/10.37040/geografie2010115010096.
Testo completoAbstract (sommario):
Anthropogenic lakes (lakes that have developed in mined-out pits as a consequence of mineral raw material mining) exhibit many interesting phenomena. Specific water features are the most remarkable, including physical, chemical and the biological characteristics. Other very specific morphometric feature of anthropogenic lake basins include the unusual location of the lake’s water surface: often several dozen meters below the adjacent terrain and the specific character of the mined-out raw materials. All of these factors affect the qualitative characteristics of lake’s water, even decades after flooding. The interaction of the factors mentioned above has resulted in the creation of a permanent meromixis in some anthropogenic lakes. The author’s primary objectives are to present some physical and chemical symptoms of meromixis at selected localities, to discuss the mutual interaction between the physical and chemical characteristics of lake water and to explore some probable causes of the origin of meromixis at the selected localities.
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Cortés-Guzmán, Daniela, e Javier Alcocer. "Turnover Drives High Benthic Macroinvertebrates’ Beta Diversity in a Tropical Karstic Lake District". Diversity 14, n. 4 (30 marzo 2022): 259. http://dx.doi.org/10.3390/d14040259.
Testo completoAbstract (sommario):
Beta diversity is useful to explain community assembly across landscapes with spatial variation. Its turnover and nestedness components help explain how beta diversity is structured across environmental and spatial gradients. Assessing beta diversity in freshwater ecosystems is essential to conservation, as it reveals the mechanisms that maintain regional diversity. Nonetheless, so far, no studies have examined the beta diversity patterns of benthic macroinvertebrates in tropical lakes. We aimed to examine the beta diversity patterns and components of the deep benthic macroinvertebrate communities of tropical Lakes of Montebello, Mexico, along spatial and environmental gradients. We used presence/absence data of deep benthic macroinvertebrates from 13 lakes distributed along environmental and spatial gradients. We calculated beta diversity indices and correlated them to each lake’s environmental and spatial variables. The macroinvertebrate communities of the Lakes of Montebello showed high beta diversity driven by a turnover pattern that emphasises the importance of regional-scale conservation efforts. Short distances between lakes and high environmental heterogeneity promoted species turnover, resulting in a great singularity level among lakes. We did not find significant correlations between the beta diversity components and the environmental variables, suggesting a random distribution given by the species’ high dispersal capacity in a reduced spatial extent across the lake district.
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Dupont, Andréanne, Morgan Botrel, Nicolas Fortin St-Gelais, Timothée Poisot e Roxane Maranger. "A social–ecological geography of southern Canadian lakes". FACETS 8 (1 gennaio 2023): 1–16. http://dx.doi.org/10.1139/facets-2023-0025.
Testo completoAbstract (sommario):
Anthropogenic pressures, including urban and agricultural expansion, can negatively influence a lake's capacity to provide aquatic ecosystem services (ES). However, identifying lakes most at risk of losing their ES (i.e., higher vulnerability) requires integrating information on lake ecological state, global change threats, and ES use. Here, we provide a social–ecological framework that combines these features within a regional context by evaluating the ecological state of 659 lakes across Canada. Using the deviation of impacted lakes from reference ones, we identified much higher total nitrogen and chloride concentrations as the main indicators of an altered lake ecological state in all regions identified. Lake ecological state was mapped using an additive colour model along with regional scores of threat levels and recreational ES use. Urban and agriculturally developed areas were linked to higher lake vulnerability and ES loss. Lakes in Southern Ontario were most concerning, being highly altered, under threat, and heavily used. Lakes near coastal urban centers were altered and used, but less threatened, whereas those in the Prairies were altered and threatened, but less used. Our novel framework provides the first social–ecological geography of Canadian lakes, and is a promising tool to assess lake state and vulnerability at scales relevant for management.
21
Wilcox, Evan J., Brent B. Wolfe e Philip Marsh. "Assessing the influence of lake and watershed attributes on snowmelt bypass at thermokarst lakes". Hydrology and Earth System Sciences 26, n. 23 (9 dicembre 2022): 6185–205. http://dx.doi.org/10.5194/hess-26-6185-2022.
Testo completoAbstract (sommario):
Abstract. Snow represents the largest potential source of water for thermokarst lakes, but the runoff generated by snowmelt (freshet) can flow beneath lake ice and via the outlet without mixing with and replacing pre-snowmelt lake water. Although this phenomenon, called “snowmelt bypass”, is common in ice-covered lakes, it is unknown which lake and watershed properties cause variation in snowmelt bypass among lakes. Understanding the variability of snowmelt bypass is important because the amount of freshet that is mixed into a lake affects the hydrological and biogeochemical properties of the lake. To explore lake and watershed attributes that influence snowmelt bypass, we sampled 17 open-drainage thermokarst lakes for isotope analysis before and after snowmelt. Isotope data were used to estimate the amount of lake water replaced by freshet and to observe how the water sources of lakes changed in response to the freshet. Among the lakes, a median of 25.2 % of lake water was replaced by freshet, with values ranging widely from 5.2 % to 52.8 %. For every metre that lake depth increased, the portion of lake water replaced by freshet decreased by an average of 13 %, regardless of the size of the lake's watershed. The thickness of the freshet layer was not proportional to maximum lake depth, so that a relatively larger portion of pre-snowmelt lake water remained isolated in deeper lakes. We expect that a similar relationship between increasing lake depth and greater snowmelt bypass could be present at all ice-covered open-drainage lakes that are partially mixed during the freshet. The water source of freshet that was mixed into lakes was not exclusively snowmelt but a combination of snowmelt mixed with rain-sourced water that was released as the soil thawed after snowmelt. As climate warming increases rainfall and shrubification causes earlier snowmelt timing relative to lake ice melt, snowmelt bypass may become more prevalent, with the water remaining in thermokarst lakes post-freshet becoming increasingly rainfall sourced. However, if climate change causes lake levels to fall below the outlet level (i.e., lakes become closed-drainage), more freshet may be retained by thermokarst lakes as snowmelt bypass will not be able to occur until lakes reach their outlet level.
22
Dickman, M., P. Hayes e J. Fortescue. "A Comparison of Two Indices of Diatom Inferred pH". Water Quality Research Journal 20, n. 1 (1 febbraio 1985): 9–24. http://dx.doi.org/10.2166/wqrj.1985.002.
Testo completoAbstract (sommario):
Abstract Autecological studies of diatoms as pH indicators have opened the way to estimating a lake's past pH on the basis of its diatom species compos it ion and relative abundance. Estimating the rate of lake acidification from its sediment subfossil diatoms is possible when these subfossils can be identified and accurately enumerated down the length of the lake sediment core. This technique holds considerable promise in assessing the temporal impact of acid precipitation for acid-sensitive lakes. When diatom inferred pH was regressed against observed pH for 23 lakes located north of Lake Superior a significant (P<0.01) correlation (r=0.71) resulted. Diatom downcore stratigraphy for two of these lakes (lakes Cs & B) indicated that their pH had dropped from 6.3 to 5.3 (Lake Cs) and from 5.6 to 5.3 (Lake B) over the last 20 years. However, when the "B" index was used instead of log alpha, no significant change in downcore diatom inferred pH was apparent for Lake B. We concluded that log alpha was overly sensitive to small changes in the relative abundance of alkaliphilic diatoms. Thus, in lakes where alkaliphilic diatoms are rare, index "B" rather than log alpha should be employed. In lakes of pH 6 or above where the relative abundance of alkaliphilic diatoms is higher (e.g. Cs & Fenton Lakes) index "B" and log alpha provide essentially identical downcore pH profiles.
23
Picazo, Antonio, Juan Antonio Villaescusa, Carlos Rochera, Javier Miralles-Lorenzo, Antonio Quesada e Antonio Camacho. "Functional Metabolic Diversity of Bacterioplankton in Maritime Antarctic Lakes". Microorganisms 9, n. 10 (1 ottobre 2021): 2077. http://dx.doi.org/10.3390/microorganisms9102077.
Testo completoAbstract (sommario):
A summer survey was conducted on the bacterioplankton communities of seven lakes from Byers Peninsula (Maritime Antarctica), differing in trophic and morphological characteristics. Predictions of the metabolic capabilities of these communities were performed with FAPROTAX using 16S rRNA sequencing data. The versatility for metabolizing carbon sources was also assessed in three of the lakes using Biolog Ecoplates. Relevant differences among lakes and within lake depths were observed. A total of 23 metabolic activities associated to the main biogeochemical cycles were foreseen, namely, carbon (11), nitrogen (4), sulfur (5), iron (2), and hydrogen (1). The aerobic metabolisms dominated, although anaerobic respiration was also relevant near the lakes’ bottom as well as in shallow eutrophic lakes with higher nutrient and organic matter contents. Capacity for using carbon sources further than those derived from the fresh autochthonous primary production was detected. Clustering of the lakes based on metabolic capabilities of their microbial communities was determined by their trophic status, with functional diversity increasing with trophic status. Data were also examined using a co-occurrence network approach, indicating that the lakes and their catchments have to be perceived as connected and interacting macrosystems, where either stochastic or deterministic mechanisms for the assembling of communities may occur depending on the lake’s isolation. The hydrological processes within catchments and the potential metabolic plasticity of these biological communities must be considered for future climate scenarios in the region, which may extend the growing season and increase biomass circulation.
24
Locke, A., D. M. Reid, H. C. van Leeuwen, W. G. Sprules e J. T. Carlton. "Ballast Wafer Exchange as a Means of Controlling Dispersal of Freshwater Organisms by Ships". Canadian Journal of Fisheries and Aquatic Sciences 50, n. 10 (1 ottobre 1993): 2086–93. http://dx.doi.org/10.1139/f93-232.
Testo completoAbstract (sommario):
During May–December 1990 and March–May 1991, 546 foreign ocean-going vessels entered the Laurentian Great Lakes and upper St. Lawrence River, areas protected by the Great Lakes Ballast Water Control Guidelines. Between 88 and 94% of the vessels exchanged their ballast water with seawater as required by the guidelines. Living representatives of 11 invertebrate phyla were sampled from ballast tanks. Between 14 and 33% of ships that exchanged freshwater ballast in midocean carried living freshwater-tolerant zooplankton at the time of entry to the Seaway, although these included many taxa already found in the Great Lakes. Four freshwater-tolerant zooplankton species that were identified as living specimens in ballast water have apparently not been recorded from the Great Lakes. Voluntary ballast water controls reduced but did not eliminate the risk of species invasion, since some ships did not comply with the guidelines, and even ships that did exchange ballast water could introduce viable freshwater-tolerant organisms into the Great Lakes. About half of the ballast water carried into the Seaway by ocean-going vessels and lakers each year originates from the St. Lawrence River, portions of which are not yet protected by any ballast controls.
25
Doulgeris, Charalampos, Panagiota Koukouli, Pantazis Georgiou, Paschalis Dalampakis e Dimitrios Karpouzos. "Assessment of Minimum Water Level in Lakes and Reservoirs Based on Their Morphological and Hydrological Features". Hydrology 7, n. 4 (6 novembre 2020): 83. http://dx.doi.org/10.3390/hydrology7040083.
Testo completoAbstract (sommario):
The sustainable management of lakes and reservoirs requires the determination of their minimum environmental water level. Even though the assessment of minimum water level depends on a number of biotic and abiotic factors of the lake ecosystem, in many cases these factors are not entirely known and, furthermore, their evaluation is usually a challenging and laborious task. On the other hand, the lakes/reservoirs may comprise an important water resource to meet the requirements arising from economic activities. In this paper, the morphological and hydrological features of four lakes of northern Greece were analysed in order to assess their minimum environmental water level. The hydromorphological analysis was based on the relationship of the lake surface area and volume with water level as well as the water inflow from the lake’s hydrological catchment area, considering as the lake’s critical volume storage, the annual water volume flowing into a lake from its hydrological catchment area with a probability of exceedance 50% of a long time series of hydrological years. By combining morphological and hydrological features, the proposed methodology aimed to extend the analysis based solely on morphological features, and assess more comprehensively the minimum environmental water level in the four lakes, ensuring also the rising from the minimum level to the maximum (overflow) level for most of the hydrological years.
26
Lisboa, Filipe, Vanda Brotas, Filipe Duarte Santos, Sakari Kuikka, Laura Kaikkonen e Eduardo Eiji Maeda. "Spatial Variability and Detection Levels for Chlorophyll-a Estimates in High Latitude Lakes Using Landsat Imagery". Remote Sensing 12, n. 18 (7 settembre 2020): 2898. http://dx.doi.org/10.3390/rs12182898.
Testo completoAbstract (sommario):
Monitoring lakes in high-latitude areas can provide a better understanding of freshwater systems sensitivity and accrete knowledge on climate change impacts. Phytoplankton are sensitive to various conditions: warmer temperatures, earlier ice-melt and changing nutrient sources. While satellite imagery can monitor phytoplankton biomass using chlorophyll a (Chl) as a proxy over large areas, detection of Chl in small lakes is hindered by the low spatial resolution of conventional ocean color satellites. The short time-series of the newest generation of space-borne sensors (e.g., Sentinel-2) is a bottleneck for assessing long-term trends. Although previous studies have evaluated the use of high-resolution sensors for assessing lakes’ Chl, it is still unclear how the spatial and temporal variability of Chl concentration affect the performance of satellite estimates. We discuss the suitability of Landsat (LT) 30 m resolution imagery to assess lakes’ Chl concentrations under varying trophic conditions, across extensive high-latitude areas in Finland. We use in situ data obtained from field campaigns in 19 lakes and generate remote sensing estimates of Chl, taking advantage of the long-time span of the LT-5 and LT-7 archives, from 1984 to 2017. Our results show that linear models based on LT data can explain approximately 50% of the Chl interannual variability. However, we demonstrate that the accuracy of the estimates is dependent on the lake’s trophic state, with models performing in average twice as better in lakes with higher Chl concentration (>20 µg/L) in comparison with less eutrophic lakes. Finally, we demonstrate that linear models based on LT data can achieve high accuracy (R2 = 0.9; p-value < 0.05) in determining lakes’ mean Chl concentration, allowing the mapping of the trophic state of lakes across large regions. Given the long time-series and high spatial resolution, LT-based estimates of Chl provide a tool for assessing the impacts of environmental change.
27
Qu, Ge, Xiaoai Dai, Junying Cheng, Weile Li, Meilian Wang, Wenxin Liu, Zhichong Yang et al. "Characterization of Long-Time Series Variation of Glacial Lakes in Southwestern Tibet: A Case Study in the Nyalam County". Remote Sensing 14, n. 19 (20 settembre 2022): 4688. http://dx.doi.org/10.3390/rs14194688.
Testo completoAbstract (sommario):
Glacial lakes are important freshwater resources in southern Tibet. However, glacial lake outburst floods have significantly jeopardized the safety of local residents. To better understand the changes in glacial lakes in response to climate change, it is necessary to conduct a long-term evaluation on the areal dynamics of glacial lakes, assisted with local observations. Here, we propose an innovative method of classification and stacking extraction to accurately delineate glacial lakes in southwestern Tibet from 1990 to 2020. Based on Landsat images and meteorological data, we used geographic detectors to detect correlation factors. Multiple regression models were used to analyze the driving factors of the changes in glacier lake area. We combined bathymetric data of the glacial lakes with the changes in climatic variables and utilized HEC-RAS to determine critical circumstances for glacial lake outbursts. The results show that the area of glacial lakes in Nyalam County increased from 27.95 km2 in 1990 to 52.85 km2 in 2020, and eight more glacial lakes were observed in the study area. The glacial lake area expanded by 89.09%, where we found significant growth from 2015 to 2020. The correlation analysis between the glacial lake area and climate change throughout the period shows that temperature and precipitation dominate the expansion of these lakes from 1990 to 2020. We also discover that the progressive increase in water volume of glacial lakes can be attributed to the constant rise in temperature and freeze–thaw of surrounding glaciers. Finally, the critical conditions for the glacial lake’s outburst were predicted by using HEC-RAS combined with the changes in the water volume and climatic factors. It is concluded that GangxiCo endures a maximum water flow of 4.3 × 108 m3, and the glacial lake is in a stable changing stage. This conclusion is consistent with the field investigation and can inform the prediction of glacial lake outbursts in southwestern Tibet in the future.
28
Nabila, Fatima Nur, Md Bodruddoza Mia, Md Yousuf Gazi, Md Mahin Uddin, Md Nahid Al Montakim e Md Mahfuz Alam. "Assessment of Water Quality and Quantity in the Lakes of Dhaka Metropolitan City - Remote Sensing, Field and Laboratory Analyses". Dhaka University Journal of Earth and Environmental Sciences 11, n. 1 (1 febbraio 2023): 27–42. http://dx.doi.org/10.3329/dujees.v11i1.63709.
Testo completoAbstract (sommario):
Lakes in the Dhaka city have been facing extreme deterioration both by quantity and quality due to rapid urban and population growth for several decades. The prime objective is to assess the spatiotemporal changes of water quality and water quantity of the Dhaka city lakes respectively using Sentinel 2B and Landsat satellite images. The study covers the major twelve lakes of the Dhaka city. The four seasonal water qualities such as chlorophyll-a concentration, trophic state index (TSI), Secchi disk depth (SDD) and turbidity were retrieved with the conventional algorithms using Sentinel 2B images. The results showed that the Uttara Park Lake reduced its area dramatically from 1972 to 2020 due to the rapid urbanization in this region. Although the Zoo Lakes areas increased more than three times but the Banani, Hatirjheel and Dhanmondi lakes reduced to about 60-75% from 1972 to 2020 due to the urbanization and filling up the lake’s area. On the other hand, Gulshan, Crescent and Ramna Lakes reduced their area slightly about 10-20% during the study period. The chlorophyll-a concentration from post to pre-monsoon, increased in six lakes (Uttara Park, Zoo North, Gulshan, Old Airport, Dhanmondi and Hatirjheel), declined in six lakes (Zoo South, Banani, Ramna, Uttara, Uttara South and Crescent) of Dhaka city. Although the TSI illustrated all lakes in the eutrophic states from post to pre-monsoon but the value of TSI increased in six lakes and declined six lakes of the twelve point samples within the retrieved spatial distribution of TSI using satellite images of Dhaka city. In case of Secchi depth, the SDD values declined from post-monsoon to pre-monsoon in all of the lakes, indicating the deteriorating water quality of the lakes. On the other hand, the turbidity values increased in all lakes of Dhaka city from post-monsoon to pre-monsoon. We observed pH values ranges from 7-9 in the lakes during the field works early March and May of 2021. The observed EC values of the lakes ranges from 148-730μs/cm and 130-690μs/cm respectively in winter and pre-monsoon seasons. None of the samples of the lakes meets the standard of dissolved oxygen (DO) collected in March, 2021, but Dhanmondi and Uttara Lake samples collected in May, 2021 meet the standard. Biological oxygen demand (BOD) value is extremely high and none of the samples meets the acceptable limit of BOD. Among the cations, only Hatirjheel, Gulshan, Uttara, Uttara South/W, Zoo South and North Lake exceeded the acceptable limit for K⁺. Among the anions, Hatirjheel, Gulshan, Banani, Uttara, Uttara South/W Lake exceed the standard for HCO3− and Hatirjheel, Gulshan, Banani, Old Airport, Uttara Park, Uttara South/W Lake exceed the standard limit for NO3−. Uttara Lake shows the maximum concentration of PO43− and does not meet the standard limit. All the samples meet the standard for Fe and Mn. The outputs of this study could be used to minimize the degradation of Dhaka city lakes both in terms of quantity and quality and will help take necessary measures for healthy and sustainable lake environment.
The Dhaka University Journal of Earth and Environmental Sciences, Vol. 11(1), 2022, P 27-42
29
Field, Hannah R., William H. Armstrong e Matthias Huss. "Gulf of Alaska ice-marginal lake area change over the Landsat record and potential physical controls". Cryosphere 15, n. 7 (15 luglio 2021): 3255–78. http://dx.doi.org/10.5194/tc-15-3255-2021.
Testo completoAbstract (sommario):
Abstract. Lakes in contact with glacier margins can impact glacier evolution as well as the downstream biophysical systems, flood hazard, and water resources. Recent work suggests positive feedbacks between glacier wastage and ice-marginal lake evolution, although precise physical controls are not well understood. Here, we quantify ice-marginal lake area change in understudied northwestern North America from 1984–2018 and investigate climatic, topographic, and glaciological influences on lake area change. We delineate time series of sampled lake perimeters (n=107 lakes) and find that regional lake area has increased 58 % in aggregate, with individual proglacial lakes growing by 1.28 km2 (125 %) and ice-dammed lakes shrinking by 0.04 km2 (−15 %) on average. A statistical investigation of climate reanalysis data suggests that changes in summer temperature and winter precipitation exert minimal direct influence on lake area change. Utilizing existing datasets of observed and modeled glacial characteristics, we find that large, wide glaciers with thick lake-adjacent ice are associated with the fastest rate of lake area change, particularly where they have been undergoing rapid mass loss in recent times. We observe a dichotomy in which large, low-elevation coastal proglacial lakes have changed most in absolute terms, while small, interior lakes at high elevation have changed most in relative terms. Generally, the fastest-changing lakes have not experienced the most dramatic temperature or precipitation change, nor are they associated with the highest rates of glacier mass loss. Our work suggests that, while climatic and glaciological factors must play some role in determining lake area change, the influence of a lake's specific geometry and topographic setting overrides these external controls.
30
Daniels, Robert A., Richard S. Morse, James W. Sutherland, Robert T. Bombard e Charles W. Boylen. "Fish Movement Among Lakes: Are Lakes Isolated". Northeastern Naturalist 15, n. 4 (dicembre 2008): 577–88. http://dx.doi.org/10.1656/1092-6194-15.4.577.
Testo completo
31
Cordeiro, Rita, Rúben Luz, Joana Vilaverde, Vitor Vasconcelos, Amélia Fonseca e Vítor Gonçalves. "Distribution of Toxic Cyanobacteria in Volcanic Lakes of the Azores Islands". Water 12, n. 12 (2 dicembre 2020): 3385. http://dx.doi.org/10.3390/w12123385.
Testo completoAbstract (sommario):
Eutrophication and global climate change gather advantageous conditions for cyanobacteria proliferation leading to bloom formation and cyanotoxin production. In the Azores, eutrophication is a major concern, mainly in lakes where fertilizers and organic matter discharges have increased nutrient concentration. In this study, we focused on understanding the influence of environmental factors and lake characteristics on (i) cyanobacteria diversity and biomass and (ii) the presence of toxic strains and microcystin, saxitoxin, anatoxin-a, and cylindrospermopsin cyanotoxin-producing genes. Fifteen lakes from the Azores Archipelago were sampled seasonally, environmental variables were recorded in situ, cyanobacteria were analyzed with microscopic techniques, and cyanotoxin-producing genes were targeted through conventional PCR. Statistical analysis (DistLM) showed that lake typology-associated variables (lake’s depth, area, and altitude) were the most explanatory variables of cyanobacteria biomass and cyanotoxin-producing genes presence, although trophic variables (chlorophyll a and total phosphorus) influence species distribution in each lake type. Our main results revealed higher cyanobacteria biomass/diversity, and higher toxicity risk in lakes located at lower altitudes, associated with deep anthropogenic pressures and eutrophication scenarios. These results emphasize the need for cyanobacteria blooms control measures, mainly by decreasing anthropogenic pressures surrounding these lakes, thus decreasing eutrophication. We also highlight the potential for microcystin, saxitoxin, and anatoxin-a production in these lakes, hence the necessity to implement continuous mitigation protocols to avoid environmental and public health toxicity events.
32
Bolch, T., M. F. Buchroithner, J. Peters, M. Baessler e S. Bajracharya. "Identification of glacier motion and potentially dangerous glacial lakes in the Mt. Everest region/Nepal using spaceborne imagery". Natural Hazards and Earth System Sciences 8, n. 6 (4 dicembre 2008): 1329–40. http://dx.doi.org/10.5194/nhess-8-1329-2008.
Testo completoAbstract (sommario):
Abstract. Failures of glacial lake dams can cause outburst floods and represents a serious hazard. The potential danger of outburst floods depends on various factors like the lake's area and volume, glacier change, morphometry of the glacier and its surrounding moraines and valley, and glacier velocity. Remote sensing offers an efficient tool for displacement calculations and risk assessment of the identification of potentially dangerous glacial lakes (PDGLs) and is especially helpful for remote mountainous areas. Not all important parameters can, however, be obtained using spaceborne imagery. Additional interpretation by an expert is required. ASTER data has a suitable accuracy to calculate surface velocity. Ikonos data offers more detail but requires more effort for rectification. All investigated debris-covered glacier tongues show areas with no or very slow movement rates. From 1962 to 2003 the number and area of glacial lakes increased, dominated by the occurrence and almost linear areal expansion of the moraine-dammed lakes, like the Imja Lake. Although the Imja Lake will probably still grow in the near future, the risk of an outburst flood (GLOF) is considered not higher than for other glacial lakes in the area. Potentially dangerous lakes and areas of lake development are identified. There is a high probability of further lake development at Khumbu Glacier, but a low one at Lhotse Glacier.
33
Li, Yunliang, Jing Yao e Li Zhang. "Investigation into mixing in the shallow floodplain Poyang Lake (China) using hydrological, thermal and isotopic evidence". Water Science and Technology 74, n. 11 (17 settembre 2016): 2582–98. http://dx.doi.org/10.2166/wst.2016.444.
Testo completoAbstract (sommario):
Although mixing in lakes has significant environmental and ecological implications, knowledge of mixing dynamics for shallow floodplain lakes has received little attention. In this study, hydrological, thermal and isotopic investigations were undertaken to provide evidence for the mixing in the large, shallow floodplain Poyang Lake (China). Depth profiles of water velocity, water temperature and stable hydrogen and oxygen isotope compositions were measured throughout the lake, with results showing that the water velocity differences in depth profiles are generally less than ∼0.2 m/s, indicating weak stratification. Although water temperature differences of up to ∼2 °C are observed occasionally, Poyang Lake appears to have isothermal mixed layers from the epilimnion to the hypolimnion, attributed to the presence of mostly small temperature differences (<1 °C). Additionally, isotope compositions reveal that the lake's water columns are almost homogeneous during various water-level periods. Relative to many lakes exhibiting either no mixing or partial mixing, Poyang Lake appears to be fully mixing on a seasonal basis, depending on hydrological forcings within the lake rather than meteorological conditions. The current study will help to improve our knowledge of water flow patterns and pollutant transport in Poyang Lake and other similar floodplain lakes.
34
Kelso, J. R. M., e M. G. Johnson. "Factors Related to the Biomass and Production of Fish Communities in Small, Oligotrophic Lakes Vulnerable to Acidification". Canadian Journal of Fisheries and Aquatic Sciences 48, n. 12 (1 dicembre 1991): 2523–32. http://dx.doi.org/10.1139/f91-293.
Testo completoAbstract (sommario):
We estimated biomass and production of the fish community in 19 small (<50 ha) lakes from four watersheds in central Ontario. Lake pH ranged from 4.8 to 7.1. We found 19 fish species in these lakes; yellow perch (Perca flavescens), pumpkinseed (Lepomis gibbosus), white sucker (Catostomus commersoni), and largemouth bass (Micropterus salmoides) were the most common. On average, there were 4.5 species per lake. Neither fish community biomass nor production was significantly different among the communities identified by cluster analysis, and the number offish species was not lower at lower pH. More than 75% of each lake's total biomass was confined to less than three fish species. Whole-lake fish biomass was related to the total number of species in the lakes and their average age. Fish community production was related to fish biomass, averge fish size, and acid neutralizing capacity (ANC) with an almost equal influence provided by each factor. At lower ANC and pH, fish were usually smaller in weight and often had lower population growth rates. In these lakes where the influence of lake size and trophic status was minimized, fish community biomass and production were only secondarily related to lake pH or ANC.
35
Olea-Olea, Selene, Raúl A. Silva-Aguilera, Javier Alcocer, Oscar Escolero, Eric Morales-Casique, Jose Roberto Florez-Peñaloza, Kevin Alexis Almora-Fonseca e Luis A. Oseguera. "Water–Rock Interaction Processes in Groundwater and Flows in a Maar Lake in Central Mexico". Water 16, n. 5 (28 febbraio 2024): 715. http://dx.doi.org/10.3390/w16050715.
Testo completoAbstract (sommario):
Tropical maar lakes are distinct ecosystems with unique ecological features. To comprehend, manage, and conserve these lakes, it is essential to understand their water sources, particularly groundwater, and the hydrogeochemical processes shaping their water chemistry. This research focuses on the maar lake Alchichica in central Mexico, known for harboring 18 new and endemic species and a ring of stromatolites. With groundwater discharge as the primary source, concerns arise over anthropic extraction impacts on water levels and stromatolite survival. Sampling six wells and one piezometer revealed major ion (Ca2+, Mg2+, K+, Na+, Cl−, HCO3−, SO42−) and trace element (Fe, Al3+, SiO2) concentrations. Geochemical evolution was explored through diagrams, geological sections, and inverse geochemical models using the PHREEQC code. Findings indicate groundwater evolving along controlled flow paths, and influencing chemical composition through water–rock interactions. The lake’s unique conditions, resulting from the mixing of two flows, enable stromatolite formation. Water level reduction appears unrelated to evaporation at the sampled sites, suggesting a need for a broader study in a larger area. Analyzing the maar lake’s hydrochemistry provides valuable insights into unique characteristics supporting high endemism in this ecosystem. This research enhances our understanding of groundwater’s geochemical processes and hydrogeochemical evolution in maar lakes, with potential applications worldwide.
36
Robertson, Dale M., e Robert A. Ragotzkie. "Thermal Structure of a Multibasin Lake: Influence of Morphometry, Interbasin Exchange, and Groundwater". Canadian Journal of Fisheries and Aquatic Sciences 47, n. 6 (1 giugno 1990): 1206–12. http://dx.doi.org/10.1139/f90-140.
Testo completoAbstract (sommario):
Interbasin differences which develop below the upper mixed layer in small multibasin lakes provide the unique opportunity to examine how a lake's morphometry affects the rates of certain processes and the distribution of certain physical, chemical, and biological parameters without the confounding inter-lake dissimilarities encountered when examining different lakes. To determine if the variability in basin morphometry can be the primary factor causing interbasin differences, we examined the thermal structure of Trout Lake, Wisconsin, during summer and winter stratification and quantitatively explained the observed differences in temperature among basins. Differences in hypolimnetic temperature during summer stratification and differences in the temperature of the entire water column in the winter were primarily due to the morphometric differences among basins. During winter, variations in the temperature among basins were also influenced by interbasin exchange and differences in groundwater inputs. Therefore, this multibasin lake can provide the opportunity to test for morphometric affects without the confounding inter-lake dissimilarities encountered when examining different lakes.
37
Son, Nguyen Hoang, Phuc Chi Lang Le, Van Chan Mai, Ngoc Bay Tran e Nam Le. "Calculating the volume of Tan Mieu lake in Thanh Noi area, Hue City, for the urban stormwater drainage system". Hue University Journal of Science: Earth Science and Environment 131, n. 4B (31 dicembre 2022): 31–41. http://dx.doi.org/10.26459/hueunijese.v131i4b.6855.
Testo completoAbstract (sommario):
Detention lakes, which are effective means of flood control, are highly effective in sustainable drainage solutions. Numerous factors diminish the regulating reservoir's function for urban drainages, such as the lake's small volume, an inadequate drainage system, and restricted outflow from the lake. Therefore, this study applies the method of limited rainfall intensity to calculate the stormwater flow into the lake and determine the volume of the detention lakes according to TCVN 7957: 2008 [1] to the sub-basin of Tan Mieu. It is confirmed that the volume of the lake in the region and the level of outflow from the lake, which are essential factors in flood mitigation, is not suitable for the rainfall characteristics of the area. The results show that with the planned outflow of Qx = 1/3 × Qt, the lake's actual capacity is roughly a half of the required lake capacity. With the option Qx = 1/2 × Qt, the actual volume of the lake is 1.2 times smaller than the calculated capacity. Therefore, increasing the lake's volume and outflow volume from the lake minimizes local flooding.
38
GAVRILESCU, Elena, e Gilda Diana BUZATU. "Water Quality of Some Lakes in Dolj County". Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Agriculture 70, n. 2 (25 novembre 2013): 370–76. http://dx.doi.org/10.15835/buasvmcn-agr:9679.
Testo completoAbstract (sommario):
In Dolj County there are a number of lakes that are particularly important, because they have a large quantity of water, some of them originating from hydrotechnical accumulations, and other from natural waters. In the present study, it was performed the monitoring of the water quality of the lakes in Dolj County, in the year of 2012, namely: Victoria - Geormane, BistreÅ£ and Caraula. The ecological conditions of the natural and artificial lakes was established based on the state of acidification, of the oxygen regime (dissolved oxygen, biochemical oxygen demand and chemical oxygen demand), the degree of eutrophication (biogenic substances, phytoplankton biomass and chlorophyll “aâ€) and also based on transparency. The water samples were taken from three points: tail, middle and upstream of the lake and were analyzed using high performance equipment, namely: pH-meter, spectrophotometer DR 2010, Sechi disc, BOD5 system. In terms of the degree of eutrophication, the water from the studied lakes belongs to the third category of water quality. Geormane is a natural lake which has a very good ecological status, except regarding the eutrophication, which is considerably visible. Bistret lake has a good environmental status and is visible eutrophic. Caraula lake’s water belongs to the third category of water quality, being heavily eutrophic.
39
Rochera, Carlos, Manuel Toro, Eugenio Rico, Eduardo Fernández-Valiente, Juan Antonio Villaescusa, Antonio Picazo, Antonio Quesada e Antonio Camacho. "Structure of planktonic microbial communities along a trophic gradient in lakes of Byers Peninsula, South Shetland Islands". Antarctic Science 25, n. 2 (20 marzo 2013): 277–87. http://dx.doi.org/10.1017/s0954102012000971.
Testo completoAbstract (sommario):
AbstractA systematic limnological survey of water bodies of Byers Peninsula (Livingston Island, South Shetland Islands) was carried out during the summer of 2001/02. Abundances of microbial plankton were determined which allowed a delineation of the pelagic food web structure. We also report the nutrient status of these lakes. We demonstrate the occurrence of a trophic gradient that extended from upland lakes (oligotrophic) to the coastal ones (eutrophic). The study shows that a lake's morphology regulates the relative importance of the pelagic and benthic habitats, whereas nutrient loads mainly determine its trophic status. Yet, some of the variability observed could be also a legacy of the landscape. Photosynthetic pigments analyses by high-performance liquid chromatography of the lake waters revealed a major occurrence of chlorophytes, chrysophytes and diatoms. The chlorophyllaconcentrations in lakes in the central plateau were consistently lower (< 2.5 μg l-1) than coastal sites, which were one order of magnitude higher. Numbers of both bacterioplankton and autotrophic picoplankton also increased from inland to coastal sites. However, the relative role of autotrophic picoplankton in the total phytoplankton assemblage decreased with the increase in nutrients loads. Our results show that the trophic status clearly plays a significant role in structuring the pelagic communities of these lakes despite climatic constraints.
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Miller, Alice. "The Lakes". Iowa Review 42, n. 2 (ottobre 2012): 140–41. http://dx.doi.org/10.17077/0021-065x.7182.
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Simmons, Beth, e Katherine Honda. "Arthur Lakes". Rocks & Minerals 84, n. 5 (settembre 2009): 426–32. http://dx.doi.org/10.3200/rmin.84.5.426-432.
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Melack, John M. "Saline Lakes". Ecology 68, n. 3 (giugno 1987): 755. http://dx.doi.org/10.2307/1938486.
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Picard, M. Dane. "Killer Lakes". Journal of Geological Education 40, n. 2 (marzo 1992): 147–50. http://dx.doi.org/10.5408/0022-1368-40.2.147.
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Siegert, M. "Antarctic Lakes". Ecological Restoration 33, n. 4 (21 ottobre 2015): 426–27. http://dx.doi.org/10.3368/er.33.4.426.
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POZO, JESÚS DEL, CARMEN PEÑA, JESÚS GARCÍA SILVA, JOSE JAIME GODAY e EDUARDO FONSECA. "Venous Lakes". Dermatologic Surgery 29, n. 3 (marzo 2003): 308–10. http://dx.doi.org/10.1097/00042728-200303000-00023.
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Kohler, Jack. "Lubricating lakes". Nature 445, n. 7130 (febbraio 2007): 830–31. http://dx.doi.org/10.1038/445830a.
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NONGWA, G. M. "African lakes". Nature 322, n. 6081 (agosto 1986): 679. http://dx.doi.org/10.1038/322679c0.
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Howard-Williams, Clive. "Antarctic Lakes". Journal of Plankton Research 37, n. 3 (22 aprile 2015): 656–57. http://dx.doi.org/10.1093/plankt/fbv030.
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Mathis, Christian. "Data Lakes". Datenbank-Spektrum 17, n. 3 (6 ottobre 2017): 289–93. http://dx.doi.org/10.1007/s13222-017-0272-7.
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Cowen, Ron. "Titan's Lakes". Science News 170, n. 6 (5 agosto 2006): 83. http://dx.doi.org/10.2307/4017045.
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