Search results for " lake"

Rumicetum palustris (TIMÁR 1950) W. FISCHER 1978, new plant community from Bidentetea tripartiti R. Tx., LOHM. ET Prsg 1950 class in SW Poland

2016

Natural water reservoirs are very valuable floristic sites in Poland. Among them, the most important for preservation of biodiversity of plant communities are lakes, rivers, oxbow lakes and fishponds. The long-term process of human pressure on habitats of this type caused disturbance to their biological balance. Changes in the water regime, industrial development and chemisation of agriculture, especially in the period of last two hundred years, led to systematic disappearance of localities of many plant communities. Rumicetum palustris (Timár 1950) W. Fischer 1978, of Bidentetea tripartiti R. Tx., Lohm. et Prsg 1950 class, has been described for the first time in Hungary and Germany. This …

Water level regulation in winter triggers fouling of fishing nets by the diatom Aulacoseira islandica in a boreal lake

2015

Water level regulation related to hydroelectric power production and flood prevention is an important hydro-morphological pressure on many watercourses around the world. Fouling of fishing nets in autumn during the open water period and in winter under the ice is a common phenomenon in large Finnish lakes where the water level is regulated. This fouling of fishing nets can sometimes be so extensive that fishing has to be stopped. Based on the practical experiences of fishermen, the main cause for the under-ice fouling has been proposed to be the winter draw-down of water causing low water level and stronger currents in lakes, but no conclusive relationship between fouling and water level re…

Insights on Hydrothermal‐Magmatic Interactions and Eruptive Processes at Poás Volcano (Costa Rica) From High‐Frequency Gas Monitoring and Drone Measu…

2019

Texto completo del documento Identification of unambiguous signals of volcanic unrest is crucial in hazard assessment. Processes leading to phreatic and phreatomagmatic eruptions remain poorly understood, inhibiting effective eruption forecasting. Our 5‐year gas record from Poás volcano, combined with geophysical data, reveals systematic behavior associated with hydrothermal‐magmatic eruptions. Three eruptive episodes are covered, each with distinct geochemical and geophysical characteristics. Periods with larger eruptions tend to be associated with stronger excursions in monitoring data, particularly in SO2/CO2 and SO2 flux. The explosive 2017 phreatomagmatic eruption was the largest erupt…

Volcanic Lakes in Africa: The VOLADA_Africa 2.0 Database, and Implications for Volcanic Hazard

2021

Volcanic lakes pose specific hazards inherent to the presence of water: phreatic and phreatomagmatic eruptions, lahars, limnic gas bursts and dispersion of brines in the hydrological network. Here we introduce the updated, interactive and open-access database for African volcanic lakes, country by country. The previous database VOLADA (VOlcanic LAke DAta Base, Rouwet et al., Journal of Volcanology and Geothermal Research, 2014, 272, 78–97) reported 96 volcanic lakes for Africa. This number is now revised and established at 220, converting VOLADA_Africa 2.0 in the most comprehensive resource for African volcanic lakes: 81 in Uganda, 37 in Kenya, 33 in Cameroon, 28 in Madagascar, 19 in Ethiop…

Multi-component gas emission measurements of the active lava lake of Nyiragongo, DR Congo

2017

Between 2007 and 2011 four measurement campaigns (June 2007, July 2010, June 2011, and December 2011) were carried out at the crater rim of Nyiragongo volcano, DR Congo. Nyiragongo is one of the most active volcanoes in Africa. The ground-based remote sensing technique Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS), which uses scattered sunlight, the in-situ Multi-Component Gas Analyzer System (Multi-GAS) and alkaline impregnated filter were simultaneously applied during all field trips. The bromine monoxide to sulfur dioxide (BrO/SO2) and carbon dioxide to sulfur dioxide (CO2/SO2) molar ratios were determined, among other ratios. During the different field trips variati…

Major and trace element geochemistry of neutral and acidic thermal springs at El Chichón volcano, Mexico

2008

Abstract Four groups of thermal springs with temperatures from 50 to 80 °C are located on the S–SW–W slopes of El Chichon volcano, a composite dome-tephra edifice, which exploded in 1982 with a 1 km wide, 160 m deep crater left. Very dynamic thermal activity inside the crater (variations in chemistry and migration of pools and fumaroles, drastic changes in the crater lake volume and chemistry) contrasts with the stable behavior of the flank hot springs during the time of observations (1974–2005). All known groups of hot springs are located on the contact of the basement and volcanic edifice, and only on the W–SW–S slopes of the volcano at almost same elevations 600–650 m asl and less than 3…

Ledājkušanas ūdeņu baseini Ziemeļlatvijas un Vidusgaujas zemienēs Vēlā Vislas leduslaikmeta beigu posmā

2014

Disertācijā aplūkoti ledājkušanas ūdeņu baseini, kuri eksistēja Ziemeļvidzemes un Vidusgaujas zemienēs vēlā Vislas leduslaikmeta deglaciācijas laikā. Pirmo reizi Latvijā iekšzemes ledājkušanas baseinu rekonstruēšanā ir ņemta vērā Zemes virsmas šķietamā pacelšanās, kā arī pašas rekonstrukcijas ir veiktas ĢIS vidē ar modelēšanas rīku palīdzību. Darbā ir veiktas Vidusgaujas, Smiltenes un Strenču ledāja sprostezeru rekonstrukcijas ūdens līmeņu kritumam no 125 līdz 46 m v.j.l., kuras parāda minēto sprostezeru izplatību, dziļumu, ūdens pieteces un noteces vietas, attīstību laikā un saistību ar citām tālaika ūdenstilpēm. Baseinus veidojošo un tiem sekojošo eolo procesu nogulumu datējumi ar OSL met…

Applicability and consequences of the integration of alternative models for CO2 transfer velocity into a process-based lake model

2019

Freshwater lakes are important in carbon cycling, especially in the boreal zone where many lakes are supersaturated with the greenhouse gas carbon dioxide (CO2) and emit it to the atmosphere, thus ventilating carbon originally fixed by the terrestrial system. The exchange of CO2 between water and the atmosphere is commonly estimated using simple wind-based parameterizations or models of gas transfer velocity (k). More complex surface renewal models, however, have been shown to yield more correct estimates of k in comparison with direct CO2 flux measurements. We incorporated four gas exchange models with different complexity into a vertical process-based physico-biochemical lake model, MyLak…

Sustainability of interlocked fishing district -management concept for commercial fishing in Finnish lake fishery

2012

Regional variations in occupancy frequency distributions patterns between odonate assemblages in Fennoscandia

2018

Odonate (damselfly and dragonfly) species richness and species occupancy frequency distributions (SOFD) were analysed in relation to geographical location in standing waters (lakes and ponds) in Fennoscandia, from southern Sweden to central Finland. In total, 46 dragonfly and damselfly species were recorded from 292 waterbodies. Species richness decreased to the north and increased with waterbody area in central Finland, but not in southern Finland or in Sweden. Species occupancy ranged from 1 up to 209 lakes and ponds. Over 50% of the species occurred in less than 10% of the waterbodies, although this proportion decreased to the north. In the southern lakes and ponds, none of the species o…