scholarly journals Interacting effects of vegetation components and water table on methane dynamics in a boreal fen

2019 ◽  
Author(s):  
Terhi Riutta ◽  
Aino Korrensalo ◽  
Anna M. Laine ◽  
Jukka Laine ◽  
Eeva-Stiina Tuittila
Keyword(s):  
Water Level ◽  
High Water ◽  
Climatic Conditions ◽  
Sphagnum Mosses ◽  
Dwarf Shrubs ◽  
Growing Seasons ◽  
Plant Groups ◽  
The Mean ◽  
Methane Dynamics

Abstract. Vegetation and hydrology are important controlling factors in peatland methane dynamics. This study aimed at investigating the role of vegetation components – sedges, dwarf-shrubs, and Sphagnum mosses – in methane fluxes of a boreal fen under natural and experimental water level drawdown conditions. We measured the fluxes during four growing seasons using static chamber technique in a field experiment where the role of the ecosystem components was assessed via plant removal treatments. The first year was a calibration year after which the water level drawdown and vegetation removal treatments were applied. Under natural water level conditions, plant-mediated fluxes comprised 68–78 % of the mean growing season flux (1.95 ± 0.21 g CH4 m−2 month−1 from June to September), of which Sphagnum mosses and sedges accounted for 1/4 and 3/4, respectively. The presence of dwarf shrubs, on the other hand, had a slightly attenuating effect on the fluxes. In water level drawdown conditions, the mean flux was close to zero (0.03 ± 0.03 g CH4 m−2 month−1) and the presence/absence of the plant groups had a negligible effect. In conclusion, water level acted as a switch; only in high water level conditions vegetation regulated the net fluxes. The results are relevant for assessing the response of peatland fluxes in changing climatic conditions, as water level drawdown and the consequent vegetation succession are the major projected impacts of climate change on northern peatlands.

scholarly journals Interacting effects of vegetation components and water level on methane dynamics in a boreal fen

2020 ◽  
Vol 17 (3) ◽  
pp. 727-740 ◽  
Author(s):  
Terhi Riutta ◽  
Aino Korrensalo ◽  
Anna M. Laine ◽  
Jukka Laine ◽  
Eeva-Stiina Tuittila
Keyword(s):  
Water Level ◽  
Natural Water ◽  
Climatic Conditions ◽  
Sphagnum Mosses ◽  
Dwarf Shrubs ◽  
Growing Seasons ◽  
Plant Groups ◽  
The Mean ◽  
Methane Dynamics

Abstract. Vegetation and hydrology are important controlling factors in peatland methane dynamics. This study aimed at investigating the role of vegetation components, sedges, dwarf shrubs, and Sphagnum mosses, in methane fluxes of a boreal fen under natural and experimental water level drawdown conditions. We measured the fluxes during growing seasons 2001–2004 using the static chamber technique in a field experiment where the role of the ecosystem components was assessed via plant removal treatments. The first year was a calibration year after which the water level drawdown and vegetation removal treatments were applied. Under natural water level conditions, plant-mediated fluxes comprised 68 %–78 % of the mean growing season flux (1.73±0.17 g CH4 m−2 month−1 from June to September), of which Sphagnum mosses and sedges accounted for one-fourth and three-fourths, respectively. The presence of dwarf shrubs, on the other hand, had a slightly attenuating effect on the fluxes. In water level drawdown conditions, the mean flux was close to zero (0.03±0.03 g CH4 m−2 month−1) and the presence and absence of the plant groups had a negligible effect. In conclusion, water level acted as a switch; only in natural water level conditions did vegetation regulate the net fluxes. The results are relevant for assessing the response of fen peatland fluxes to changing climatic conditions, as water level drawdown and the consequent vegetation succession are the major projected impacts of climate change on northern peatlands.

scholarly journals PRE- and POST-STORM LiDAR SURVEYS FOR ASSESSMENT OF IMPACT ON COASTAL EROSION

2019 ◽  
Vol XLII-3/W8 ◽  
pp. 261-266
Author(s):  
A.-L. Montreuil ◽  
M. Chen ◽  
A. Esquerré ◽  
R. Houthuys ◽  
R. Moelans ◽  
...  
Keyword(s):  
Management Practices ◽  
Morphological Changes ◽  
Storm Surges ◽  
High Water ◽  
Water Levels ◽  
Airborne Lidar ◽  
Coastline Change ◽  
The Mean ◽  
The Impact

<p><strong>Abstract.</strong> Sustainable management of the coastal resources requires a better understanding of the processes that drive coastline change. The coastline is a highly dynamic sea-terrestrial interface. It is affected by forcing factors such as water levels, waves, winds, and the highest and most severe changes occur during storm surges. Extreme storms are drivers responsible for rapid and sometimes dramatic changes of the coastline. The consequences of the impacts from these events entail a broad range of social, economic and natural resource considerations from threats to humans, infrastructure and habitats. This study investigates the impact of a severe storm on coastline response on a sandy multi-barred beach at the Belgian coast. Airborne LiDAR surveys acquired pre- and post-storm covering an area larger than 1 km<sup>2</sup> were analyzed and reproducible monitoring solutions adapted to assess beach morphological changes were applied. Results indicated that the coast retreated by a maximum of 14.7 m where the embryo dunes in front of the fixed dunes were vanished and the foredune undercut. Storm surge and wave attacks were probably the most energetic there. However, the response of the coastline proxies associated with the mean high water line (MHW) and dunetoe (DuneT) was spatially variable. Based on the extracted beach features, good correlations (r>0.73) were found between coastline, berm and inner intertidal bar morphology, while it was weak with the most seaward bars covered in the surveys. This highlights the role of the upper features on the beach to protect the coastline from storm erosion by reducing wave energy. The findings are of critical importance in improving our knowledge and forecasting of coastline response to storms, and also in its translation into management practices.</p>

scholarly journals Modern changes of nutrients’ removal into the southern forest zone rivers of Volga basin

2019 ◽  
pp. 43-55
Author(s):  
S. V. Dolgov ◽  
N. I. Koronkevich
Keyword(s):  
High Water ◽  
Climatic Conditions ◽  
Russian Plain ◽  
Nutrients Removal ◽  
Forest Zone ◽  
River Catchment ◽  
Cheboksary Reservoir ◽  
Anthropogenic Component ◽  
Underground Flow

The article analyzes on the example of the Linda river basin, the tributary of the Cheboksary reservoir, contribution of the main elements of its vertical hydrological structure (precipitation, surface and underground runoff, verhovodka runoff) in the formation of nutrients removal from rivers catchments in the southern forest zone of the Russian plain. The removal of nutrients from the Linda river catchment area with various elements of water flow for the year, its high-water and low-water periods was calculated. It is shown that due to the increased role of the changed hydro-climatic conditions, especially due to the increased flow of infiltration origin (underground and verhovodka runoff), the nutrients removal has increased in recent years. Anthropogenic component of nutrient leaching into the Cheboksary reservoir from Linda river catchment was identified. It is reduced in recent decades by the background dispersion in the catchment, diffuse nutrients leaching to surface and underground flow of natural origin.

scholarly journals Plant indication of thermocarst forms in palsa mires in the south of Nature Park Numto (West Siberia)

2019 ◽  
Vol 9 (1) ◽  
pp. 27-57
Author(s):  
E.A. Shishkonankova ◽  
N.A. Avetov ◽  
T.Yu. Tolpysheva ◽  
A.A. Tarlinskaya
Keyword(s):  
West Siberia ◽  
The South ◽  
Southern Limit ◽  
Sphagnum Mosses ◽  
Dwarf Shrubs ◽  
Mobile Species ◽  
Nature Park ◽  
Downy Birch

Currently, palsa mires in the southern limit of circumpolar permafrost zone are characterized by an increased intensity of thermokarst processes. In the south of Nature Park Numto the cyclic character of frozen mound formation was replaced by their unidirectional degradation as a result of thaw. We analyze plant indicators of various thermokarst forms occurring in mounds: denudation spots, slumps and funnels. Depending on the stages of thermokarst and type of palsas (flat mound or large mound ones) a number of plant indicators of thawing is revealed: “the drunken forest”, the loss of dwarf shrubs and lichens and their secondary colonization, eutrophication of communities, the emergence of the “ridges” of vegetatively mobile species and others. Brown mosses and secondary colonizing Cladonia lichens with cup-shaped and club-like podetia are indicators of slow thermokarst on patches of denudation in large mounds. Meanwhile, the role of Cladonia lichens with richly branched podetia is markedly reduced. Mesotrophic communities, dominated by mesotrophic sphagnum mosses, are formed in deep funnels on large mounds under the conditions of frozen bed existence. The development of eutrophic communities indicates the release of nutrients during the melting of peat. The stages of thermokarst on the flat palsa mounds correspond to the following succession row: lichens + dwarf shrubs → hygrophyte sphagnum mosses and / or brown mosses + liverworts → hygro-hydrophyte sphagnum mosses + Warnstorfia fluitans. Reliable and the most long-term indicator of thermokarst on large mounds is the downy birch (Betula pubescens).

6. An Investigation of the Spatial Differences in Mercury Burdens of Small Fish in a St-Lawrence River Impoundment Reservoir: the Role of Water Level Fluctuations

2016 ◽  
Author(s):  
Michele Parisien
Keyword(s):  
Water Level ◽  
High Water ◽  
Water Level Fluctuations ◽  
Small Fish ◽  
Water Reservoirs ◽  
Hydroelectric Reservoirs ◽  
Spatial Differences ◽  
Reducing Bacteria ◽  
St Lawrence River

In many hydroelectric reservoirs across Canada, fish exhibit elevated mercury burdens. This is thought to occur due to the flooding of soil with water level fluctuations. Periods ofhigh water level may cause mercury from shoreline soil to be released into the water, which may make it available for methylation by sulfur-reducing bacteria in the sedimentand phytoplankton on plants. The amount of methylmercury produced during periods of high water level may depend on the topography of the shoreline; if the shoreline has agentle slope, more of its surface area would be covered during rises in water level than if the shoreline has a steep slope. I hypothesize that bays within a reservoir that have a gentle slope and a relatively large amount of vegetation (vegetation provides habitat for periphyton) will have more mercury than steeply-sloped bays with little vegetation. Totest this hypothesis, I have collected 10 each of the 3 most abundant fish (≤100 mm) from 3 bays in eastern Lake St. Lawrence (an impoundment reservoir with water fluctuations ≤2meters throughout the year) at Massena, NY. I will use stable isotopes to infer the trophic level and food web of each fish in order to determine spatial patterns of mercurydistribution. This study may improve our knowledge of mercury methylation patters in water reservoirs, and provide us with information necessary to properly manage the StLawrenceRiver water reservoirs.   

scholarly journals Hydroclimatic and Geological Conditions of the Variability of Fluvial Transport Rate in the Upper Part of the Wieprz River Catchment

2015 ◽  
Vol 34 (1) ◽  
pp. 5-14
Author(s):  
Andrzej Świeca ◽  
Waldemar Kociuba ◽  
Teresa Brzezińska-Wójcik
Keyword(s):  
High Water ◽  
Climatic Conditions ◽  
Transport Rate ◽  
River Catchment ◽  
Fluvial Transport ◽  
Geological Conditions ◽  
The Mean ◽  
Variable Water

Abstract The article summarises the results of observations conducted in the periods 1989-1992, 1998-2000, and 2001- 2003 in the catchment of the Roztocze section of the Wieprz River with an area of 404 km2. The presented results of the study on fluvial transport document the response of an upland river to variable hydro-climatic conditions. Fluvial transport rate in periods extreme in hydrological terms was compared. In the conditions of low water stages (1989- 1992) and mean annual discharges lower than the mean multiannual by 19%, the Wieprz River discharged an average of 13300 tonnes of solutions and 485 tonnes of suspensions annually. The unitary indices amounted to 32.7 and 1.2 t/ km2/year, respectively. In the years 1998-2000, in the conditions of high water stages and mean annual discharges higher than the multiannual by 41%, the Wieprz River discharged approximately 22,800 tonnes of solutions and 981 tonnes of suspensions annually. The unitary indices increased proportionately to 56.2 t/km2/year and 2.4 t/km2/year, respectively. In the years 2001-2003, in the conditions of variable water stages and discharges higher than the multiannual by 12%, the Wieprz River discharged an average of approximately 17,500 tonnes of solutions and 441 tonnes of suspensions annually. The unitary indices reached the values of 43.3 t/km2/year and 1.1 t/km2/year, respectively.

Long-term dynamics and destruction of marsh vegetation in the Kolokolkova Bay of the Barents Sea

2012 ◽  
pp. 66-77 ◽  
Author(s):  
I. A. Lavrinenko ◽  
O. V. Lavrinenko ◽  
D. V. Dobrynin
Keyword(s):  
Species Composition ◽  
Plant Communities ◽  
Barents Sea ◽  
Mean Value ◽  
Marsh Vegetation ◽  
Composition And Structure ◽  
The Mean ◽  
Species Composition And Structure

The satellite images show that the area of marshes in the Kolokolkova bay was notstable during the period from 1973 up to 2011. Until 2010 it varied from 357 to 636 ha. After a severe storm happened on July 24–25, 2010 the total area of marshes was reduced up to 43–50 ha. The mean value of NDVI for studied marshes, reflecting the green biomass, varied from 0.13 to 0.32 before the storm in 2010, after the storm the NDVI decreased to 0.10, in 2011 — 0.03. A comparative analysis of species composition and structure of plant communities described in 2002 and 2011, allowed to evaluate the vegetation changes of marshes of the different topographic levels. They are fol­lowing: a total destruction of plant communities of the ass. Puccinellietum phryganodis and ass. Caricetum subspathaceae on low and middle marches; increasing role of halophytic species in plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. typicum on middle marches; some changes in species composition and structure of plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. festucetosum rubrae on high marches and ass. Parnassio palustris–Salicetum reptantis in transition zone between marches and tundra without changes of their syntaxonomy; a death of moss cover in plant communities of the ass. Caricetum mackenziei var. Warnstorfia exannulata on brackish coastal bogs. The possible reasons of dramatic vegetation dynamics are discussed. The dating of the storm makes it possible to observe the directions and rates of the succession of marches vegetation.

Seasonal trends in the stable isotopic composition of snow and meltwater runoff in a subarctic catchment at Okstindan, Norway

2004 ◽  
Vol 35 (2) ◽  
pp. 119-137 ◽  
Author(s):  
S.D. Gurney ◽  
D.S.L. Lawrence
Keyword(s):  
Isotopic Composition ◽  
Mean Value ◽  
Mean Values ◽  
Stable Isotopic Composition ◽  
Meltwater Runoff ◽  
Stable Isotopic ◽  
The Mean ◽  
The Difference ◽  
Δ18o And Δd

Seasonal variations in the stable isotopic composition of snow and meltwater were investigated in a sub-arctic, mountainous, but non-glacial, catchment at Okstindan in northern Norway based on analyses of δ18O and δD. Samples were collected during four field periods (August 1998; April 1999; June 1999 and August 1999) at three sites lying on an altitudinal transect (740–970 m a.s.l.). Snowpack data display an increase in the mean values of δ18O (increasing from a mean value of −13.51 to −11.49‰ between April and August), as well as a decrease in variability through the melt period. Comparison with a regional meteoric water line indicates that the slope of the δ18O–δD line for the snowpacks decreases over the same period, dropping from 7.49 to approximately 6.2.This change points to the role of evaporation in snowpack ablation and is confirmed by the vertical profile of deuterium excess. Snowpack seepage data, although limited, also suggest reduced values of δD, as might be associated with local evaporation during meltwater generation. In general, meltwaters were depleted in δ18O relative to the source snowpack at the peak of the melt (June), but later in the year (August) the difference between the two was not statistically significant. The diurnal pattern of isotopic composition indicates that the most depleted meltwaters coincide with the peak in temperature and, hence, meltwater production.

The Synod of Pistoia and Vatican II

2019 ◽  
Author(s):  
Shaun Blanchard
Keyword(s):  
Eighteenth Century ◽  
Vatican Ii ◽  
High Water ◽  
Church Reform ◽  
Second Vatican Council ◽  
Vatican Council ◽  
Bible Reading ◽  
Different Levels ◽  
Continuity And Discontinuity

This book sheds further light on the nature of church reform and the roots of the Second Vatican Council (1962–65) through a study of eighteenth-century Catholic reformers who anticipated the Council. The most striking of these examples is the Synod of Pistoia (1786), the high-water mark of late Jansenism. Most of the reforms of the Synod were harshly condemned by Pope Pius VI in the bull Auctorem fidei (1794), and late Jansenism was totally discredited in the ultramontane nineteenth-century Church. Nevertheless, much of the Pistoian agenda—such as an exaltation of the role of bishops, an emphasis on infallibility as a gift to the entire Church, religious liberty, a simpler and more comprehensible liturgy that incorporates the vernacular, and the encouragement of lay Bible reading and Christocentric devotions—was officially promulgated at Vatican II. The career of Bishop Scipione de’ Ricci (1741–1810) and the famous Synod he convened are investigated in detail. The international reception (and rejection) of the Synod sheds light on why these reforms failed, and the criteria of Yves Congar are used to judge the Pistoian Synod as “true or false reform.” This book proves that the Synod was a “ghost” present at Vatican II. The council fathers struggled with, and ultimately enacted, many of the same ideas. This study complexifies the story of the roots of the Council and Pope Benedict XVI’s “hermeneutic of reform,” which seeks to interpret Vatican II as in “continuity and discontinuity on different levels” with past teaching and practice.

scholarly journals Forensic Investigation of Four Monitored Green Infrastructure Inlets

Water ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 1787
Author(s):  
Leena J. Shevade ◽  
Franco A. Montalto
Keyword(s):  
Measurement Uncertainty ◽  
Green Infrastructure ◽  
Stormwater Management ◽  
Catchment Area ◽  
Low Flow ◽  
Inflow Rate ◽  
Forensic Investigation ◽  
Flow Conditions ◽  
The Mean

Green infrastructure (GI) is viewed as a sustainable approach to stormwater management that is being rapidly implemented, outpacing the ability of researchers to compare the effectiveness of alternate design configurations. This paper investigated inflow data collected at four GI inlets. The performance of these four GI inlets, all of which were engineered with the same inlet lengths and shapes, was evaluated through field monitoring. A forensic interpretation of the observed inlet performance was conducted using conclusions regarding the role of inlet clogging and inflow rate as described in the previously published work. The mean inlet efficiency (meanPE), which represents the percentage of tributary area runoff that enters the inlet was 65% for the Nashville inlet, while at Happyland the NW inlet averaged 30%, the SW inlet 25%, and the SE inlet 10%, considering all recorded events during the monitoring periods. The analysis suggests that inlet clogging was the main reason for lower inlet efficiency at the SW and NW inlets, while for the SE inlet, performance was compromised by a reverse cross slope of the street. Spatial variability of rainfall, measurement uncertainty, uncertain tributary catchment area, and inlet depression characteristics are also correlated with inlet PE. The research suggests that placement of monitoring sensors should consider low flow conditions and a strategy to measure them. Additional research on the role of various maintenance protocols in inlet hydraulics is recommended.

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