scholarly journals The geochemistry of upland ponds, Taylor Valley, Antarctica

2011 ◽  
Vol 24 (1) ◽  
pp. 3-14 ◽  
Author(s):  
W. Berry Lyons ◽  
Kathleen A. Welch ◽  
Christopher B. Gardner ◽  
Chris Jaros ◽  
Daryl L. Moorhead ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Dilution Effect ◽  
Climatic Conditions ◽  
Water Bodies ◽  
Primary Control ◽  
Dry Valleys ◽  
Stream Channels ◽  
Taylor Valley ◽  
Free Region ◽  
The Impact

AbstractThe McMurdo Dry Valleys of Antarctica are the largest ice-free region on the continent. These valleys contain numerous water bodies that receive seasonal melt from glaciers. For forty years, research emphasis has been placed on the larger water bodies, the permanent ice-covered lakes. We present results from the first study describing the geochemistry of ponds in the higher elevations of Taylor Valley. Unlike the lakes at lower elevations, the landscape on which these ponds lie is among the oldest in Taylor Valley. These upland ponds wax and wane in size depending on the local climatic conditions, and their ionic concentrations and isotopic composition vary annually depending on the amount of meltwater generated and their hydrologic connectivity. This study evaluates the impact of changes in summer climate on the chemistry of these ponds. Although pond chemistry reflects the initial meltwater chemistry, dissolution and chemical weathering within the stream channels, and possibly permafrost fluid input, the primary control is the dilution effect of glacier melt during warmer summers. These processes lead to differences in solute concentrations and ionic ratios between ponds, despite their nearby proximity. The change in size of these ponds over time has important consequences on their geochemical behaviour and potential to provide water and solutes to the subsurface.

scholarly journals Environmental Impact Statement on Kolleru Lake Water

2020 ◽  
Vol 8 (6) ◽  
pp. 2509-2512
Keyword(s):  
Surface Water ◽  
Lake Water ◽  
Urban Areas ◽  
Water Source ◽  
Agricultural Runoff ◽  
Climatic Conditions ◽  
Water Bodies ◽  
Surface Water Bodies ◽  
Alternative Water ◽  
The Impact

Catchments are most important for the purpose of practicing irrigation and recharging groundwater by collecting water during the rainy season so that the nearby land will be in surplus quantity of groundwater due to the continues percolation of water from the catchments, even the stored water in the form of catchments will be used as an alternative water source for other requirements apart from the irrigation practices such as for industries and other developmental activities taking place nearby the catchments. Year by year it was noticed that in the world scenario the pollutant concentration is keep on increasing especially water and air pollution due to the excessive load of population that is increasing from the rural to urban areas [10]. Coming to water pollution the major portion of pollution is increasing in the surface water bodies [4] due to various activities like surface runoff, intentionally releasing of untreated effluents from the nearby industries into the catchments [8] and the agricultural runoff etc, whatever the reason there is an immediate need and an emergency to monitor these catchments as the average rainfall is gradually decreasing due to the changing climatic conditions like global warming which leads to the reduced availability of water in the surface water bodies at the other side the existing water is being contaminated [5] by the activities of nearby people. The impact will be severe when the same situation continues in the days to come where the living standards of the people will be decreased at a notable level and the impact will be much more severe on the irrigated land which depends on the catchments. The study has done at Kolleru Lake in west godavari district, Andhra Pradesh. Collected Six Water samples from six locations around the lake for analysis [7] and then the results of the analysis compared with Central Pollution Control Board 1979and Indian standards 1982 guidelines for water in the surface water bodies to find out the present scenario of lake water.

Spread of denudational processes in seepage channels in a postglacial area (north-western Poland)

2020 ◽  
Author(s):  
Małgorzata Mazurek
Keyword(s):  
Mass Movement ◽  
Climatic Conditions ◽  
Stream Channels ◽  
Infiltration Capacity ◽  
Stream Network ◽  
Alluvial Deposits ◽  
Seepage Erosion ◽  
Groundwater Sapping ◽  
The Impact ◽  
North Western

<p>Erosion by emerging groundwater (i.e., seepage erosion or groundwater sapping) is the primary mechanism initiating stream channels (so-called seepage channels) and headward growth in lowland areas with a high infiltration capacity of sediment where the surface runoff is relatively rarely observed. Around groundwater outflows, as a result of the impact of denudational processes, develops an alcove, which is an amphitheatrical depression, often of steep slopes, separated from the slopes of the initial depression with clear edges. A spring-formed alcove is the upper boundary of a concentrated flow of water and sediment transport between well-marked channel margins. The influence of groundwater remains one of the least understood factors in the landform evolution in the postglacial zone of Western Pomerania (north-western Poland).</p><p>Morphometric and lithological surveying of about 80 spring-formed alcoves were studied in the southern part of the Parsęta catchment (NW Poland) made it possible to identify morphological effects of seepage erosion which are combined with surface wash and mass movement processes. The co-occurrence of various denudational processes in the headwater zones produces variations in the accumulation conditions, and as a result, a diversity of deposits. The mineral series includes erosional pavements, colluvium, and alluvial deposits. Changes in hydrodynamic conditions are favourable to organic accumulation (peats and organic-mineral muds) as well as  chemical and biochemical deposition (calcareous tufa and precipitation of Fe-oxides). Seepage channels grow when they attract enough groundwater to remove clastic material from the heads. Depending on the discharge volume of the outflow from the ten observed spring-formed alcoves (1-73 L/s), products of mechanical denudation (4-54 mg/L) are transported from the slope system to the fluvial system.</p><p>The morphometry of the spring-formed alcoves as well as deposits found in them reflect stages of their development. Changes in the development of the channel heads occur as a result of variations in the groundwater table that are due to changes in climatic conditions or land use. The determination of the place and formation of the beginning of a river channel initiated by groundwater outflows is of key importance for the modelling of the development of a stream network.</p>

Morphodynamique fluviale et neotectonique dans la vallee de l'Oise (Bassin parisien, France)

2000 ◽  
Vol 171 (5) ◽  
pp. 577-585 ◽  
Author(s):  
Jean-Pierre Larue
Keyword(s):  
Climatic Conditions ◽  
Dry Valleys ◽  
Fluvial Dynamics ◽  
Longitudinal Profiles ◽  
The Impact

Abstract To show the impact of neotectonics on fluvial morphodynamics, the author presents a geomorphological study of the Oise valley where it crosses the Pays de Bray anticline, and of the gullies and the dry valleys of the Pays de Thelle. The analysis of alluvial and colluvial forms and formations makes it possible to reconstruct the longitudinal profiles of successive river beds, from the valley heads to the Oise valley and thus to reveal anomalies. Tectonics control fluvial dynamics, but impacts are only observed if the climatic conditions are favourable: hence it can be deduced that the gullies were formed during the wet Subboreal period.

scholarly journals The impact of fossil fuel burning related to scientific activities in the McMurdo Dry Valleys, Antarctica: Revisited

Elem Sci Anth ◽  
2018 ◽  
Vol 6 ◽  
Author(s):  
W. Berry Lyons ◽  
Elsa Saelens ◽  
Kathleen A. Welch
Keyword(s):  
Fossil Fuel ◽  
Austral Summer ◽  
Dry Valleys ◽  
Carbon And Nitrogen ◽  
Fossil Fuel Burning ◽  
Taylor Valley ◽  
Fuel Burning ◽  
Field Season ◽  
C And N ◽  
The Impact

Fossil fuel use associated with scientific activities in the Taylor Valley, Antarctic has been examined to determine the fluxes of particulate organic and elemental carbon and nitrogen as well as NOx for the 2015–2016 austral summer field season. These carbon and nitrogen fluxes are compared to our previously published calculations for the 1997–1998 austral summer. In addition, we compile fossil fuel usage and resulting C and N fluxes from the major field camp in Taylor Valley, Lake Hoare Camp (LHC) from the late 1990’s through 2017. In general, the annual fluxes do vary from year to year, but there is no significant trend, at least during the primary summer field season. There is indication that increasing the length of scientific operations does increase the C and N inputs via fossil fuel burning. This works supports our original results demonstrating that over long periods of time the anthropogenic flux of N from local fossil fuel burning could become quantitatively important in the region. Although the particulate C fluxes remain very low, the recent finding of black carbon in the Taylor Valley landscape indicates more on-going monitoring of the source of this material is merited.

scholarly journals Continental weathering using combined Hf-Nd isotope system and clay mineralogy: new insights for the Late Cretaceous climate

2021 ◽  
Author(s):  
Pauline Corentin ◽  
Emmanuelle Puceat ◽  
Pierre Pellenard ◽  
Nicolas Freslon ◽  
Michel Guiraud ◽  
...  
Keyword(s):  
Clay Mineral ◽  
Late Cretaceous ◽  
Chemical Weathering ◽  
Clay Mineralogy ◽  
Global Scale ◽  
Climatic Conditions ◽  
Silicate Weathering ◽  
Nd Isotope ◽  
Continental Weathering ◽  
The Impact

<p>The Late Cretaceous period records a pronounced decrease in marine temperatures at a global scale initiating the last greenhouse-icehouse transition, whose origin still remains enigmatic. Continental weathering represents a major sink of atmospheric CO<sub>2</sub> through silicate weathering reactions yet the importance of this process in the Late Cretaceous cooling has only been scarcely explored.</p><p>In this study we explore the impact of the eastern South American margin uplift, concomitant to the long-term Late Cretaceous cooling, on the evolution of chemical weathering of the Brazilian margin, using a new proxy of silicate weathering based on the coupled Lu-Hf and Sm-Nd isotope systems in clays. This proxy, expressed as Δε<sub>Hf</sub>, has been recently calibrated in modern environments (Bayon et al., 2016) but has only been scarcely applied to deep-time environments. This proxy, applied on sediments from DSDP site 356 on the São Paulo Plateau, highlights a marked increase in silicate chemical weathering of the southeastern Brazilian margin from the Santonian to the Maastrichtian, also supported by the evolution of the chemical index of alteration (CIA) and clay mineralogy.</p><p>This increase follows an episode of enhanced mechanical erosion of the margin revealed in the Turonian to Santonian by an increase of primary clay mineral (illite, chlorite) and Ti/Al ratio, linked to the tectonic uplift of the margin. Clay mineral assemblages additionally point to an evolution of local climatic conditions from arid to a more hydrolysing climate following this episode, that we link to a “rain shadow effect” affecting the eastern side of the newly formed relief that would have enhanced chemical weathering of the margin.</p><p>Importantly the temporal coincidence of the increase in chemical weathering depicted here with the marked acceleration of the global cooling recorded worldwide during the Campanian points to a potentially important role of this process on the overall climate decline initiating the descent into our icehouse climate mode. Although records from additional sites are needed to establish the spatial extent of the margin affected by this process, our new dataset brings new insights about the impact of tectonic forcing on climate.</p><p>Bayon et al. (2016) EPSL 438, p. 25-36.</p>

Geochemistry of the Eocene clastic sediments (Suonahu Formation) in the North Qiangtang Basin, Tibet: implications for paleoclimate conditions, provenance and tectonic setting

2020 ◽  
Vol 57 (1) ◽  
pp. 40-55
Author(s):  
Lijun Shen ◽  
Jian Wang ◽  
Hualiang Shen ◽  
Xiugen Fu ◽  
Youli Wan ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Tectonic Setting ◽  
Major Elements ◽  
Climatic Conditions ◽  
Igneous Rocks ◽  
Source Rocks ◽  
Primary Control ◽  
Element Abundances ◽  
Qiangtang Basin ◽  
Clastic Sediments

The geochemistry of the clastic sedimentary units of the Suonahu Formation from the QD17 well in the northern Qiangtang basin, Tibet, was studied using various chemical analyses. SiO2/Al2O3 ratios indicated that compositional maturity and recycling of the sediments were low to moderate. The total rare earth element (∑REE) contents of the clastic sediments ranged from 29.28 to 191.92 ppm. Element abundances suggest that the studied clastic sediments in the northern Qiangtang Basin were mainly sourced from felsic rocks mixed with small amounts of intermediate rocks, and that they were mostly developed in a continental setting. The REE geochemistry of the clastic sediments suggests that these different lithological samples were derived from a similar terrigenous source and that the Eu anomaly was inherited from the source rocks. The paleoclimate index (C-value) varied from 0.01 to 0.36, reflecting generally arid to semiarid conditions. In addition, Rb/Sr (about 0.41) and Sr/Cu (about 37.02) ratios support the idea that arid conditions prevailed during the deposition of the Suonahu Formation. Sr/Ba ratios (0.48–3.23) suggest a paleoenvironment with variable salinity. The covariation among this factor and paleoclimate indicators suggests that variations in climatic conditions exerted a primary control on salinity. The chemical index of alteration (CIA), A–CN–K ternary diagram, and low Th/U ratios indicate that the parent rocks of the clastic sediments experienced weak chemical weathering. Two multidimensional tectonic discrimination diagrams based on major elements show that the Suonahu Formation was deposited in a rift-related basin. The TiO2 versus Zr, La/Th versus Hf, and Co/Th versus La/Sc bivariate diagrams and multi-major elements discrimination diagram indicate that the detritus was primarily derived from felsic igneous rocks with less contribution from intermediate igneous rocks.

scholarly journals Holstein Friesian dairy cattle edited for diluted coat color as adaptation to climate change

2020 ◽  
Author(s):  
G. Laible ◽  
S-A. Cole ◽  
B. Brophy ◽  
J. Wei ◽  
S. Leath ◽  
...  
Keyword(s):  
Dairy Cattle ◽  
Coat Color ◽  
Dilution Effect ◽  
Climatic Conditions ◽  
White Coat ◽  
Production Traits ◽  
Adaptation To Climate Change ◽  
Black And White ◽  
Holstein Friesian ◽  
The Impact

AbstractHigh-producing Holstein Friesian dairy cattle have a characteristic black and white coat pattern where black frequently comprises a large proportion of the coat. Compared to a light coat color, black absorbs more solar radiation translating into radiative heat gain which is a contributing factor to heat stress in cattle, negatively impacting on their production levels, fertility and welfare. To better adapt dairy cattle to the rapidly changing climatic conditions with predictions for more frequent and prolonged hot temperature patterns, we aimed to lighten their coat color by genome editing. Using gRNA/Cas9-mediated editing, we introduced a three base pair (bp) deletion in the pre-melanosomal protein 17 gene (PMEL) proposed as the causative variant responsible for the semi-dominant color dilution phenotype seen in Galloway and Highland cattle. Calves generated from cells homozygous for the edited mutation revealed a strong color dilution effect. Instead of the characteristic black and white coat color patterning of control calves generated from unedited parental cells, the edited calves displayed a novel pattern of grey and white markings and absence of any black areas. This, for the first time, verified the causative nature of the PMEL mutation for diluting the black coat color in cattle. With these edited animals, it is now possible to dissect the effects of the introgressed edit and other interfering allelic variants that might exist in individual cattle and accurately determine the impact of only the three bp change on important health, welfare and production traits. In addition, our study proved targeted editing as a promising approach for the rapid adaptation of livestock to changing climatic conditions.

scholarly journals The assemblages of transparent heavy minerals in Quaternary sediments of the Kielce-Łagów Valley (Holy Cross Mountains, Poland)

Geologos ◽  
2013 ◽  
Vol 19 (1-2) ◽  
pp. 95-129 ◽  
Author(s):  
Małgorzata Ludwikowska-Kędzia
Keyword(s):  
Chemical Weathering ◽  
Climatic Conditions ◽  
Parent Material ◽  
Heavy Minerals ◽  
Quaternary Sediments ◽  
Quaternary Deposits ◽  
Holy Cross Mountains ◽  
Mineral Assemblages ◽  
Sandy Sediments ◽  
The Impact

Abstract The composition of the transparent heavy-mineral assemblages (0.25-0.1 mm) in Quaternary slope, karst, glacial, fluvioglacial and fluvial deposits with different parent material was investigated in the Kielce-Łagów Valley (the central part of the Palaeozoic core of the Holy Cross Mountains). For the purpose, 93 samples of mostly sandy sediments were examined. Some marker and some supporting minerals can be distinguished. Slope and karst deposits are dominated by the abrasion-resistant minerals zircon, tourmaline, staurolite and rutile. This assemblage points at a source consisting of strongly weathered pre-Quaternary bedrock. Glacial and fluvioglacial deposits are dominated by medium-resistant and non-resistant minerals (garnet, amphibole, pyroxene and biotite). The two types of parent material of the heavy minerals are typical of the Quaternary deposits in the Polish uplands. The two sources are most clear in the younger (Vistulian and Holocene), mostly fluvial sediments. The results of the analysis imply that the impact of Pleistocene glaciers on the central part of the Holy Cross Mountains was neither large enough to hide the local mineralogical background, nor sufficient to dominate over the main processes transforming the mineral composition under the variable climatic conditions of the Quaternary, including aeolian processes and chemical weathering.

Spatial variations in the geochemistry of glacial meltwater streams in the Taylor Valley, Antarctica

2010 ◽  
Vol 22 (6) ◽  
pp. 662-672 ◽  
Author(s):  
Kathleen A. Welch ◽  
W. Berry Lyons ◽  
Carla Whisner ◽  
Christopher B. Gardner ◽  
Michael N. Gooseff ◽  
...  
Keyword(s):  
Chemical Weathering ◽  
Freezing Point ◽  
Mcmurdo Dry Valleys ◽  
Dry Valleys ◽  
Stream Chemistry ◽  
Glacial Meltwater ◽  
Taylor Valley ◽  
Air Temperatures ◽  
Wide Range ◽  
Long Term Ecological Research

AbstractStreams in the McMurdo Dry Valleys, Antarctica, flow during the summer melt season (4–12 weeks) when air temperatures are close to the freezing point of water. Because of the low precipitation rates, streams originate from glacial meltwater and flow to closed-basin lakes on the valley floor. Water samples have been collected from the streams in the Dry Valleys since the start of the McMurdo Dry Valleys Long-Term Ecological Research project in 1993 and these have been analysed for ions and nutrient chemistry. Controls such as landscape position, morphology of the channels, and biotic and abiotic processes are thought to influence the stream chemistry. Sea-salt derived ions tend to be higher in streams that are closer to the ocean and those streams that drain the Taylor Glacier in western Taylor Valley. Chemical weathering is an important process influencing stream chemistry throughout the Dry Valleys. Nutrient availability is dependent on landscape age and varies with distance from the coast. The streams in Taylor Valley span a wide range in composition and total dissolved solids and are surprisingly similar to a wide range of much larger temperate and tropical river systems.

Impact of roof shading on building energy performance in warm & humid climatic places of India

2020 ◽  
pp. 50-64
Author(s):  
Kuladeep Kumar Sadevi ◽  
Avlokita Agrawal
Keyword(s):  
Energy Consumption ◽  
Energy Conservation ◽  
Energy Performance ◽  
General Assumption ◽  
Climatic Conditions ◽  
Building Envelope ◽  
Passive Cooling ◽  
Base Case ◽  
U Value ◽  
The Impact

With the rise in awareness of energy efficient buildings and adoption of mandatory energy conservation codes across the globe, significant change is being observed in the way the buildings are designed. With the launch of Energy Conservation Building Code (ECBC) in India, climate responsive designs and passive cooling techniques are being explored increasingly in building designs. Of all the building envelope components, roof surface has been identified as the most significant with respect to the heat gain due to the incident solar radiation on buildings, especially in tropical climatic conditions. Since ECBC specifies stringent U-Values for roof assembly, use of insulating materials is becoming popular. Along with insulation, the shading of the roof is also observed to be an important strategy for improving thermal performance of the building, especially in Warm and humid climatic conditions. This study intends to assess the impact of roof shading on building’s energy performance in comparison to that of exposed roof with insulation. A typical office building with specific geometry and schedules has been identified as base case model for this study. This building is simulated using energy modelling software ‘Design Builder’ with base case parameters as prescribed in ECBC. Further, the same building has been simulated parametrically adjusting the amount of roof insulation and roof shading simultaneously. The overall energy consumption and the envelope performance of the top floor are extracted for analysis. The results indicate that the roof shading is an effective passive cooling strategy for both naturally ventilated and air conditioned buildings in Warm and humid climates of India. It is also observed that a fully shaded roof outperforms the insulated roof as per ECBC prescription. Provision of shading over roof reduces the annual energy consumption of building in case of both insulated and uninsulated roofs. However, the impact is higher for uninsulated roofs (U-Value of 3.933 W/m2K), being 4.18% as compared to 0.59% for insulated roofs (U-Value of 0.33 W/m2K).While the general assumption is that roof insulation helps in reducing the energy consumption in tropical buildings, it is observed to be the other way when insulation is provided with roof shading. It is due to restricted heat loss during night.

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