Search results for: winter precipitation

Authors: T. Deepa, S. R. Inchara, S. V. Venkatesh, Seema Tharannum

Abstract:

Concrete is the most widely used structural material. It is made using locally available materials. However, Concrete has low tensile strength and may crack in the early days with exothermic hydration. Bacillus subtilis bacteria that form endospores is the biological agent considered in this study for Biomineralization or MICP (Microbially Induced Calcite Precipitation) Technique and to address the increased Construction water demand, Recycled Grey Water which is obtained from STP of PES University, opted in place of Potable water. In this work, M30 grade conventional concrete is designed using OPC 53 grade cement, Manufactured Sand, Natural coarse aggregates, and Potable water. Conventional Concrete (CC), Bacterial Concrete with Potable water (BS), and Recycled Grey Water concrete (RGW) are the three different concrete specimens casted. Experimental studies such as the strength test and the surface hardness test are conducted on Conventional and Bacterial concrete samples after 7, 28, and 56 days of curing. Concrete cubes are subjected to a temperature of 50° C to investigate the effect of higher temperature. Cracked cube specimens are observed for Self-healing - as well as microstructure analysis with Scanning Electron Microscope (SEM), Energy Dispersive X-Ray Analysis (EDAX), and X-Ray Diffraction Analysis (XRD).Noticeable Calcium salt deposition is observed on the surface of BS and RGW cracked specimen. Surface hardness and EDAX test gave promising result on the advantage of using spore-forming bacteria in concrete. This is followed by the strength gain in Compression and Flexure. Results also indicate that Recycled Grey Water can be a substitute for Normal water in concrete.

Keywords: bacillus subtilis, bacterial concrete, recycled grey water, self-healing, surface hardness of concrete

Procedia PDF Downloads 111

Authors: Eyob Belew Abebe

Abstract:

Nickel-rich layered oxide cathode materials having a Ni content of ≥ 90% have great potential for use in next-generation lithium-ion batteries (LIBs), due to their high energy densities and relatively low cost. They suffer, however, from poor cycling performance and rate capability, significantly hampering their widespread applicability. In this study we synthesized a Ni-rich precursor through a co-precipitation method and added different amounts of Li-excess on the precursors using a solid-state method to obtain sintered Li1+x(Ni0.9Co0.05Mn0.05)1–xO2 (denoted as L1+x-NCM; x = 0.00, 0.02, 0.04, 0.06, and 0.08) transition metal (TM) oxide cathode materials. The L1+x-NCM cathode having a Li-excess of 4% exhibited a discharge capacity of ca. 216.17 mAh g–1 at 2.7–4.3 V, 0.1C and retained 95.7% of its initial discharge capacity (ca. 181.39 mAh g–1) after 100 cycles of 1C charge/discharge which is the best performance as compared with stoichiometric Li1+x(Ni0.9Co0.05Mn0.05)1-xO2 (i.e. x=0, Li:TM = 1:1). Furthermore, a high-rate capability of ca. 162.92 mAh g–1 at a rate of 10C, led to the 4% Li-excess optimizing the electrochemical performance, relative to the other Li-excess samples. Ex/in-situ X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy revealed that the 4% Li-excess in the Ni-rich NCM90 cathode material: (i). decreased the Li+/Ni2+ disorder by increasing the content of Ni3+ in the TM slab, (ii). increased the crystallinity, and (iii). accelerated Li+ ion transport by widening the Li-slab. Furthermore, electrochemical impedance spectroscopy and cyclic voltammetry confirmed that the appropriate Li-excess lowered the electrochemical impedance and improved the reversibility of the electrochemical reaction. Therefore, our results revealed that NCM90 cathode materials featuring an optimal Li-excess are potential candidates for use in next-generation Li-ion batteries.

Keywords: LiNi₀.₉Co₀.₀₉Mn₀.₀₉O₂, li-excess, cation mixing, structure change, cycle stability, electrochemical properties

Procedia PDF Downloads 143

Authors: Victoria Bessonova, Robert Dorrell, Nina Dethlefs, Evdokia Tapoglou, Katharine York

Abstract:

As the global pursuit of renewable energy intensifies, offshore wind farms have emerged as a promising solution to combat climate change. The global offshore wind installed capacity is projected to increase 56-fold by 2055. However, the impacts of climate change, particularly changes in wave climate, are not widely understood. Offshore wind installation and maintenance activities often require specific weather windows, characterized by calm seas and low wave heights, to ensure safe and efficient operations. However, climate change-induced alterations in wave characteristics can reduce the availability of suitable weather windows, leading to delays and disruptions in project timelines. it applied the operational limits of installation and maintenance vessels to past and future climate wave projections. This revealed changes in the annual and monthly accessibility of offshore wind farms at key global development locations. When accessibility is only defined by significant wave height, spatial patterns in the annual accessibility roughly follow changes in significant wave height, with increased availability where significant wave height is decreasing. This resulted in a 1-6% increase in Europe and North America and a similar decrease in South America, Australia and Asia. Monthly changes suggest unchanged or slightly decreased (1-2%) accessibility in summer months and increased (2-6%) in winter. Further assessment includes assessing the sensitivity of accessibility to operational limits defined by wave height combined with wave period and wave height combined with wind speed. Results of this assessment will be included in the presentation. These findings will help stakeholders inform climate change adaptations in installation and maintenance planning practices.

Keywords: climate change, offshore wind, offshore wind installation, operations and maintenance, wave climate, wind farm accessibility

Procedia PDF Downloads 60

Authors: Kartikey Gupta

Abstract:

Global warming and environmental degradation are at their peak today, with the years after 2000A.D. giving way to 15 hottest years in terms of average temperatures. In India, much of the standard temperature measuring equipment are located in ‘developed’ urban areas, hence showing us an incomplete picture in terms of the climate across many rural areas, which comprises most of the landmass. This study showcases data studied by the author since 3 years at Vatsalya’s Children’s village, in outskirts of Jaipur, Rajasthan, India; in the midst of semi-arid topography, where consistently huge temperature differences of up to 15.8 degrees Celsius from local Jaipur weather only 30 kilometers away, are stunning yet scary at the same time, encouraging analysis of where the natural climatic pattern is heading due to rapid unrestricted urbanization. Record-breaking data presented in this project enforces the need to discuss causes and recovery techniques. This research further explores how and to what extent we are causing phenomenal disturbances in the natural meteorological pattern by urban growth. Detailed data observations using a standardized ambient weather station at study site and comparing it with closest airport weather data, evaluating the patterns and differences, show striking differences in temperatures, wind patterns and even rainfall quantity, especially during high-pressure zone days. Winter-time lows dip to 8 degrees below freezing with heavy frost and ice, while only 30 kms away minimum figures barely touch single-digit temperatures. Human activity is having an unprecedented effect on climatic patterns in record-breaking trends, which is a warning of what may follow in the next 15-25 years for the next generation living in cities, and a serious exploration into possible solutions is a must.

Keywords: climate change, meteorology, urban heat island, urbanization

Procedia PDF Downloads 65

Authors: G. Nampa, M. Ndlovu

Abstract:

Mutualistic relationships amongst organisms drive diversity in terrestrial ecosystems. Yet, few mutual associations have been documented in the semi-arid savannas of Africa. The levels and benefits of association between Carissa bispinosa, a medium-sized evergreen thorny shrub, and Trinervitermes trinervoides, an ecosystem engineer termite species, were studied at a semi-arid savanna setting in Nylsvley nature reserve, South Africa. It was hypothesized that there would be a close plant-insect association since termite mounds provide nutrients for plant growth and, in return, the thorny shrubs protect mounds from predation and also provide a temperature buffer. Comparative plant and mounds measurements were taken from associated and isolated occurrences seasonally. Soil particle size, macro- and micronutrients were also evaluated from mounds and the adjacent topsoil matrix General Additive Mixed Models were used to assess internal mound temperatures in relation to prevailing ambient and plant shade temperatures. Findings revealed that plants growing on mounds were significantly taller with a wider canopy and remained greener in the dry season with more fruits. On the other hand, termite mounds under plants were less prone to be damaged by aardvarks and pangolins and had a significantly wider diameter than exposed mounds. All soil macronutrients except for calcium and phosphorous were enriched in mounds relative to the matrix. Only Manganese was enriched in mounds while the other micronutrients (Cu, Fe, Zn and B) were not. Termite mounds under plants maintained a better constant and higher mean internal temperature during winter compared to exposed mounds. To our best knowledge, the study has revealed a previously undocumented survival mechanism that termites use to escape extreme temperatures and predation in semi-arid savannas.

Keywords: mound, mutualism, soil nutrients, termites, thermoregulation

Procedia PDF Downloads 107

Authors: Sonu Khanal, Mandira Shrestha

Abstract:

Snow and Glaciers are the largest dependable reserved sources of water for the river system originating from the Himalayas so an accurate estimate of the volume of water contained in the snowpack and the rate of release of water from snow and glaciers are, therefore, needed for efficient management of the water resources. This research assess the fusion of energy exchanges between the snowpack, air above and soil below according to mass and energy balance which makes it apposite than the models using simple temperature index for the snow and glacier melt computation. UEBGrid a Distributed energy based model is used to calculate the melt which is then routed by Geo-SFM. The model robustness is maintained by incorporating the albedo generated from the Landsat-7 ETM images on a seasonal basis for the year 2002-2003 and substrate map derived from TM. The Substrate file includes predominantly the 4 major thematic layers viz Snow, clean ice, Glaciers and Barren land. This approach makes use of CPC RFE-2 and MERRA gridded data sets as the source of precipitation and climatic variables. The subsequent model run for the year between 2002-2008 shows a total annual melt of 17.15 meter is generate from the Marshyangdi Basin of which 71% is contributed by the glaciers , 18% by the rain and rest being from the snow melt. The albedo file is decisive in governing the melt dynamics as 30% increase in the generated surface albedo results in the 10% decrease in the simulated discharge. The melt routed with the land cover and soil variables using Geo-SFM shows Nash-Sutcliffe Efficiency of 0.60 with observed discharge for the study period.

Keywords: Glacier, Glacier melt, Snowmelt, Energy balance

Procedia PDF Downloads 437

Authors: Sadia Imran, Zenab Naseem

Abstract:

Dengue fever is one of the most alarming mosquito-borne viral diseases. Dengue virus has been distributed over the years exponentially throughout the world be it tropical or sub-tropical regions of the world, particularly in the last ten years. Changing topography, climate change in terms of erratic seasonal trends, rainfall, untimely monsoon early or late and longer or shorter incidences of either summer or winter. Globalization, frequent travel throughout the world and viral evolution has lead to more severe forms of Dengue. Global incidence of dengue infections per year have ranged between 50 million and 200 million; however, recent estimates using cartographic approaches suggest this number is closer to almost 400 million. In recent years, Pakistan experienced a deadly outbreak of the disease. The reason could be that they have the maximum exposure outdoors. Public organizations have observed that changing climate, especially lower average summer temperature, and increased vegetation have created tropical-like conditions in the city, which are suitable for Dengue virus growth. We will conduct a time-series analysis to study the interrelationship between dengue incidence and diurnal ranges of temperature and humidity in Pakistan, Lahore being the main focus of our study. We have used annual data from 2005 to 2015. We have investigated the relationship between climatic variables and dengue incidence. We used time series analysis to describe temporal trends. The result shows rising trends of Dengue over the past 10 years along with the rise in temperature & rainfall in Lahore. Hence this seconds the popular statement that the world is suffering due to Climate change and Global warming at different levels. Disease outbreak is one of the most alarming indications of mankind heading towards destruction and we need to think of mitigating measures to control epidemic from spreading and enveloping the cities, countries and regions.

Keywords: Dengue, epidemic, globalization, climate change

Procedia PDF Downloads 213

Authors: A. Baaloudj, F. Samraoui, B. Samraoui

Abstract:

We have been studied the reproductive ecology and dispersal of Yellow-legged Gull Larus michahellis for three years 2009-2011. The study of the breeding ecology of the species was undertaken at the Srigina Island (Skikda). The mean clutch size was 2.64±0.62, 2.49±0.72 and 2.37±0.77eggsin the three study years 2009-2011 respectively. Hatching success was similar for the first two years of study (53% in 2009and 54% in 2010) but significantly lower in the third year (27% in 2011). The same trend was found for the fledging success, it was 33% and 32% in 2009and 2010respectivelyandonly 14% in 2011. Cannibalism and predation by cats were the two likely causes of low reproductive success in the third year. Regarding the species dispersal, we started a banding program of the yellow-legged gulls Larus michahellis michahellis in 2009, the first scheme of its kind in North Africa. Banding of chicks was initiated at Skikda and extended, a year later, to four other colonies located along the Algerian coast. Preliminary analysis of ringed yellow-legged gulls from Algerian colonies indicates that juveniles dispersed in a north-westerly direction to the Balearic Sea, the Bay of Biscay, the Alboran Sea and the western Atlantic coast from the Bay of Cadiz to the Galician shores. Preliminary data suggested two distinct routes: gulls from the eastern North African colonies moved N/NW to eastern Spain and overland to the Bay of Biscay, a pattern of dispersal previously reported for birds from Spanish and French western Mediterranean colonies. Juveniles from western colonies seemed also to move N/NW to the Alboran Sea and the Bay of Cadiz. In Spain, where most of the dispersal took place, data suggested that Algerian gulls occupied coastal areas which are used as aestivating refuges before returning to North Africa in late autumn and winter.

Keywords: breeding ecology, population dynamic, dispersal, yellow-legged gull larus michahellis, sea bird, banding scheme, Srigina, Algeria

Procedia PDF Downloads 182

Authors: Strahinja Kovacevic, Milica Karadzic Banjac, Jasmina Vitas, Stefan Vukmanovic, Radomir Malbasa, Lidija Jevric, Sanja Podunavac-Kuzmanovic

Abstract:

The present study deals with chemometric regression analysis of quality parameters and the radical scavenging ability of kombucha fermented kefir-like products obtained with winter savory (WS), peppermint (P), stinging nettle (SN) and wild thyme tea (WT) kombucha inoculums. Each analyzed sample was described by milk fat content (MF, %), total unsaturated fatty acids content (TUFA, %), monounsaturated fatty acids content (MUFA, %), polyunsaturated fatty acids content (PUFA, %), the ability of free radicals scavenging (RSA Dₚₚₕ, % and RSA.ₒₕ, %) and pH values measured after each hour from the start until the end of fermentation. The aim of the conducted regression analysis was to establish chemometric models which can predict the radical scavenging ability (RSA Dₚₚₕ, % and RSA.ₒₕ, %) of the samples by correlating it with the MF, TUFA, MUFA, PUFA and the pH value at the beginning, in the middle and at the end of fermentation process which lasted between 11 and 17 hours, until pH value of 4.5 was reached. The analysis was carried out applying univariate linear (ULR) and multiple linear regression (MLR) methods on the raw data and the data standardized by the min-max normalization method. The obtained models were characterized by very limited prediction power (poor cross-validation parameters) and weak statistical characteristics. Based on the conducted analysis it can be concluded that the resulting radical scavenging ability cannot be precisely predicted only on the basis of MF, TUFA, MUFA, PUFA content, and pH values, however, other quality parameters should be considered and included in the further modeling. This study is based upon work from project: Kombucha beverages production using alternative substrates from the territory of the Autonomous Province of Vojvodina, 142-451-2400/2019-03, supported by Provincial Secretariat for Higher Education and Scientific Research of AP Vojvodina.

Keywords: chemometrics, regression analysis, kombucha, quality control

Procedia PDF Downloads 120

Authors: Weishou Shen, Changxin Zou, Dong Liu

Abstract:

High-mountain environments are experiencing more rapid warming than lowlands. The Tibetan (Qinghai-Xizang, TP) Plateau, known as the “Third Pole” of the Earth and the “Water Tower of Asia,” is the highest plateau in the world, however, ecological response to climate change has been hardly documented in high altitude regions. In this paper, we investigated climate warming induced ecological changes on the Tibetan Plateau over the past 50 years through combining remote sensing data with a large amount of in situ field observation. The results showed that climate warming up to 0.41 °C/10 a has greatly improved the heat conditions on the TP. Lake and river areas exhibit increased trend whereas swamp area decreased in the recent 35 years. The expansion in the area of the lake is directly related to the increase of precipitation as well as the climate warming up that makes the glacier shrink, the ice and snow melting water increase and the underground frozen soil melting water increase. Climate warming induced heat condition growth and reduced annual range of temperature, which will have a positive influence on vegetation, agriculture production and decreased freeze–thaw erosion on the TP. Terrestrial net primary production and farmland area on the TP have increased by 0.002 Pg C a⁻¹ and 46,000 ha, respectively. We also found that seasonal frozen soil depth decreased as the consequence of climate warming. In the long term, accelerated snow melting and thinned seasonal frozen soil induced by climate warming possibly will have a negative effect on alpine ecosystem stability and soil preservation.

Keywords: global warming, alpine ecosystem, ecological response, remote sensing

Procedia PDF Downloads 259

Authors: Kanika S. Raheja, A. Pandey, Shaila Bahl, Pratik Kumar, S. P. Lochab

Abstract:

The subject of undertaking for this paper is the study of BaSO4 nanophosphor doped with Europium in which mainly the concentration of the rare earth impurity Eu (0.05, 0.1, 0.2, 0.5, and 1 mol %) has been varied. A comparative study of the thermoluminescence(TL) properties of the given nanophosphor has also been done using a well-known standard dosimetry material i.e. TLD-100.Firstly, a number of samples were prepared successfully by the chemical co-precipitation method. The whole lot was then compared to a well established standard material (TLD-100) for its TL sensitivity property. BaSO4:Eu ( 0.2 mol%) showed the highest sensitivity out of the lot. It was also found that when compared to the standard TLD-100, BaSo4:Eu (0.2mol%) showed surprisingly high sensitivity for a large range of doses. The TL response curve for all prepared samples has also been studied over a wide range of doses i.e 10Gy to 2kGy for gamma radiation. Almost all the samples of BaSO4:Eu showed a remarkable linearity for a broad range of doses, which is a characteristic feature of a fine TL dosimeter. The graph remained linear even beyond 1kGy for gamma radiation. Thus, the given nanophosphor has been successfully optimised for the concentration of the dopant material to achieve its highest TL sensitivity. Further, the comparative study with the standard material revealed that the current optimised sample shows an astonishingly better TL sensitivity and a phenomenal linear response curve for an incredibly wide range of doses for gamma radiation (Co-60) as compared to the standard TLD-100, which makes the current optimised BaSo4:Eu quite promising as an efficient gamma radiation dosimeter. Lastly, the present phosphor has been optimised for its annealing temperature to acquire the best results while also studying its fading and reusability properties.

Keywords: gamma radiation, nanoparticles, radiation dosimetry, thermoluminescence

Procedia PDF Downloads 413

Authors: P. Mirahmadpour, M. H. Banitaba, D. Nematollahi

Abstract:

The chemistry of coordination polymers in recent years has grown exponentially not only because of their interesting architectures but also due to their various technical applications in many fields including ion exchange, chemical catalysis, small molecule separations, and drug release. The use of bridging ligands for the controlled self-assembly of one, two or three dimensional metallo-supramolecular species is the subject of serious study in last decade. Numerous different synthetic methods have been offered for the preparation of coordination polymers such as (a) diffusion from the gas phase, (b) slow diffusion of the reactants into a polymeric matrix, (c) evaporation of the solvent at ambient or reduced temperatures, (d) temperature controlled cooling, (e) precipitation or recrystallisation from a mixture of solvents and (f) hydrothermal synthesis. The electrosynthetic process suggested several advantages over conventional approaches. A general advantage of electrochemical synthesis is that it allows synthesis under milder conditions than typical solvothermal or microwave synthesis. In this work we have introduced a simple electrochemical method for growing metal coordination polymers based on copper with a flexible 2,2’-thiodiacetic acid (TDA) and rigid 1,2,4,5-benzenetetracarboxylate (BTC) ligands. The structure of coordination polymers were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), elemental analysis, thermal gravimetric (TG) and differential thermal analyses (DTA). The single-crystal X-ray diffraction analysis revealed that different conformations of the ligands and different coordination modes of the carboxylate group as well as different coordination geometries of the copper atoms. Electrochemical synthesis of coordination polymers has different advantages such as faster synthesis at lower temperature in compare with conventional chemical methods and crystallization of desired materials in a single synthetic step.

Keywords: 1, 2, 4, 5-benzenetetracarboxylate, coordination polymer, copper, 2, 2’-thiodiacetic acid

Procedia PDF Downloads 185

Authors: Hossein Mohammadzadeh, Mojtaba Heydarizad

Abstract:

Among various water resources, the surface water has a dominant role in providing water supply in the arid and semi-arid region of Iran. Andarokh-Kardeh basin is located in 50 km from Mashhad city - the second biggest city of Iran (NE of Iran), draining by Kardeh river which provides a significant portion of potable and irrigation water needs for Mashhad. The stable isotopes (¹⁸O, ²H,¹³C-DIC, and ¹³C-DOC), as reliable and precious water fingerprints, have been measured in Kardeh river (Kharket, Mareshk, Jong, All and Kardeh stations) and in Kardeh dam reservoirs (at five different sites S1 to S5) during March to June 2011 and June 2012. On δ¹⁸O vs. δ²H diagram, the river samples were plotted between Global and Eastern Mediterranean Meteoric Water lines (GMWL and EMMWL) which demonstrate that various moisture sources are providing humidity for precipitation events in this area. The enriched δ¹⁸O and δ²H values (-6.5 ‰ and -44.5 ‰ VSMOW) of Kardeh dam reservoir are compared to Kardeh river (-8.6‰and-54.4‰), and its deviation from Mashhad meteoric water line (MMWL- δ²H=7.16δ¹⁸O+11.22) is due to evaporation from the open surface water body. The enriched value of δ ¹³C-DIC and high amount of DIC values (-7.9 ‰ VPDB and 57.23 ppm) in the river and Kardeh dam reservoir (-7.3 ‰ VPDB and 55.53 ppm) is due to dissolution of Mozdooran Carbonate Formation lithology (Jm1 to Jm3 units) (contains enriched δ¹³C DIC values of 9.2‰ to 27.7‰ VPDB) in the region. Because of the domination of C3 vegetations in Andarokh_Kardeh basin, the δ¹³C-DOC isotope of the river (-28.4‰ VPDB) and dam reservoir (-32.3‰ VPDB) demonstrate depleted values. Higher DOC concentration in dam reservoir (2.57 ppm) compared to the river (0.72 ppm) is due to more biologogical activities and organic matters in dam reservoir.

Keywords: Dam reservoir, Iran, Kardeh river, Khorasan razavi, Stable isotopes

Procedia PDF Downloads 252

Authors: Nishi Bhuvandas, P. V. Timbadiya, P. L. Patel, P. D. Porey

Abstract:

Recent perceived climate variability raises concerns with unprecedented hydrological phenomena and extremes. Distribution and circulation of the waters of the Earth become increasingly difficult to determine because of additional uncertainty related to anthropogenic emissions. According to the sixth Intergovernmental Panel on Climate Change (IPCC) Technical Paper on Climate Change and water, changes in the large-scale hydrological cycle have been related to an increase in the observed temperature over several decades. Although many previous research carried on effect of change in climate on hydrology provides a general picture of possible hydrological global change, new tools and frameworks for modelling hydrological series with nonstationary characteristics at finer scales, are required for assessing climate change impacts. Of the downscaling techniques, dynamic downscaling is usually based on the use of Regional Climate Models (RCMs), which generate finer resolution output based on atmospheric physics over a region using General Circulation Model (GCM) fields as boundary conditions. However, RCMs are not expected to capture the observed spatial precipitation extremes at a fine cell scale or at a basin scale. Statistical downscaling derives a statistical or empirical relationship between the variables simulated by the GCMs, called predictors, and station-scale hydrologic variables, called predictands. The main focus of the paper is on the need for using statistical downscaling techniques for projection of local hydrometeorological variables under climate change scenarios. The projections can be then served as a means of input source to various hydrologic models to obtain streamflow, evapotranspiration, soil moisture and other hydrological variables of interest.

Keywords: climate change, downscaling, GCM, RCM

Procedia PDF Downloads 384

Authors: S. Jaikeaw, S. Chavadej

Abstract:

The objective of this study was to determine the effects of COD loading rate on hydrogen and methane production and micronutrient transportation using a two-stage upflow anaerobic sludge blanket (UASB) system under mesophilic temperature (37°C) with a constant recycle ratio of 1:1 (final effluent flow rate: feed flow rate). The first (hydrogen) UASB unit having 4 L liquid holding volume was controlled at pH 5.5 but the second (methane) UASB unit having 24 L liquid holding volume had no pH control. The two-stage UASB system operated at different COD loading rates from 8 to 20 kg/m³d based on total UASB working volume. The results showed that, at the optimum COD loading rate of 13 kg/m³d, the produced gas from the hydrogen UASB unit contained 1.5% H₂, 16.5% CH₄, and 82% CO₂ with H₂S of 252 ppm and also provided a hydrogen yield of 1.66 mL/g COD removed (or 0.56 mL/g COD applied) and a specific hydrogen production rate of 156.85 ml H₂/LRd (or 5.12 ml H₂/g MLVSS d). Under the optimum COD loading rate, the produced gas from the methane UASB unit mainly contained methane and carbon dioxide without hydrogen of 74 and 26%, respectively with hydrogen sulfide of 287 ppm and the system also provided a maximum methane yield of 407.00 mL/g COD removed (or 263.23 mL/g COD applied) and a specific methane production rate of 2081.44 ml CH₄/LRd (or 99.75 ml CH₄/g MLVSS d). Under the optimum COD loading rate, all micronutrients markedly dropped by the sulfide precipitation reactions. The reduction of micronutrients mostly appeared in the methane UASB unit. Under the studied conditions, both Co and Ni were found to be greatly precipitated out, causing the deficiency to microbial activity. It is hypothesized that an addition of both Co and Ni can improve the methanogenic activity.

Keywords: hydrogen and methane production, ethanol wastewater, a two-stage upflow anaerobic blanket (UASB) system, mesophillic temperature, microbial concentration (MLVSS), micronutrients

Procedia PDF Downloads 270

Authors: Amit G. Dhorde

Abstract:

It is now well established that the global surface air temperatures have increased significantly during the period that followed the industrial revolution. One of the main predictions of climate change is that the occurrences of extreme weather events will increase in future. In many regions of the world, high-temperature extremes have already started occurring with rising frequency. The main objective of the present study is to understand spatial and temporal changes in days with heat and cold wave conditions over southern India. The study area includes the region of India that lies to the south of Tropic of Cancer. To fulfill the objective, daily maximum and minimum temperature data for 80 stations were collected for the period 1969-2006 from National Data Center of India Meteorological Department. After assessing the homogeneity of data, 62 stations were finally selected for the study. Heat and cold waves were classified as slight, moderate and severe based on the criteria given by Indias' meteorological department. For every year, numbers of days experiencing heat and cold wave conditions were computed. This data was analyzed with linear regression to find any existing trend. Further, the time period was divided into four decades to investigate the decadal frequency of the occurrence of heat and cold waves. The results revealed that the average annual temperature over southern India shows an increasing trend, which signifies warming over this area. Further, slight cold waves during winter season have been decreasing at the majority of the stations. The moderate cold waves also show a similar pattern at the majority of the stations. This is an indication of warming winters over the region. Besides this analysis, other extreme indices were also analyzed such as extremely hot days, hot days, very cold nights, cold nights, etc. This analysis revealed that nights are becoming warmer and days are getting warmer over some regions too.

Keywords: heat wave, cold wave, southern India, decadal frequency

Procedia PDF Downloads 116

Authors: Tatyana T. Tabakova, Elitsa N. Kolentsova, Dimitar Y. Dimitrov, Krasimir I. Ivanov, Yordanka G. Karakirova, Petya Cv. Petrova, Georgi V. Avdeev

Abstract:

The catalytic oxidation of CO and volatile organic compounds (VOCs) is considered as one of the most efficient ways to reduce harmful emissions from various chemical industries. The effectiveness of gold-based catalysts for many reactions of environmental significance was proven during the past three decades. The aim of this work was to combine the favorable features of Au and Cu-Ce mixed oxides in the design of new catalytic materials of improved efficiency and economic viability for removal of air pollutants in waste gases from formaldehyde production. Supported oxides of copper and cerium with Cu: Ce molar ratio 2:1 and 1:5 were prepared by wet impregnation of g-alumina. Gold (2 wt.%) catalysts were synthesized by a deposition-precipitation method. Catalysts characterization was carried out by texture measurements, powder X-ray diffraction, temperature programmed reduction and electron paramagnetic resonance spectroscopy. The catalytic activity in the oxidation of CO, CH₃OH and (CH₃)₂O was measured using continuous flow equipment with fixed bed reactor. Both Cu-Ce/alumina samples demonstrated similar catalytic behavior. The addition of gold caused significant enhancement of CO and methanol oxidation activity (100 % degree of CO and CH₃OH conversion at about 60 and 140 ^oC, respectively). The composition of Cu-Ce mixed oxides affected the performance of gold-based samples considerably. Gold catalyst on Cu-Ce/γ-Al₂O₃ 1:5 exhibited higher activity for CO and CH₃OH oxidation in comparison with Au on Cu-Ce/γ-Al₂O₃ 2:1. The better performance of Au/Cu-Ce 1:5 was related to the availability of highly dispersed gold particles and copper oxide clusters in close contact with ceria.

Keywords: CO and VOCs oxidation, copper oxide, Ceria, gold catalysts

Procedia PDF Downloads 295

Authors: Kamila Weissova, Jitka Skrabalova, Katerina Skalova, Jana Koprivova, Zdenka Bendova

Abstract:

Any Arctic visitor has to deal with extreme conditions, including constant light during the summer season or constant darkness during winter time. Light/dark cycle is the most powerful synchronizing signal for biological clock and the absence of daily dark period during the polar day can significantly alter the functional state of the internal clock. However, the inner clock can be synchronized by other zeitgebers such as physical activity, food intake or social interactions. Here, we investigated the effect of polar day on circadian clock of 10 researchers attending the polar base station in the Svalbard region during July. The data obtained on Svalbard were compared with the data obtained before the researchers left for the expedition (in the Czech Republic). To determine the state of circadian clock we used wrist actigraphy followed by sleep diaries, saliva, and buccal mucosa samples, both collected every 4 hours during 24h-interval to detect melatonin by radioimmunoassay and clock gene (PER1, BMAL1, NR1D1, DBP) mRNA levels by RT-qPCR. The clock gene expression was analyzed using cosinor analysis. From our results, it is apparent that the constant sunlight delayed melatonin onset and postponed the physical activity in the same order. Nevertheless, the clock gene expression displayed higher amplitude on Svalbard compared to the amplitude detected in the Czech Republic. These results have suggested that the common daily schedule at the Svalbard expedition can strengthen circadian rhythm in the environment that is lacking light/dark cycle. In conclusion, the constant sunlight delays melatonin onset, but it still maintains its rhythmic secretion. The effect of constant sunlight on circadian clock can be minimalized by common daily scheduled activity.

Keywords: actighraph, clock genes, human, melatonin, polar day

Procedia PDF Downloads 146

Authors: Aurora Gitto, Philipp Proksch

Abstract:

The presence of various microorganisms (bacteria, fungi) in surface water and groundwater represents an important issue for human health worldwide. The matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF-MS) has emerged as a promising and reliable tool for bacteria identification in clinical diagnostic microbiology and environmental strains thanks to an ionization technique that uses a laser energy absorbing matrix to create ions from large molecules with minimal fragmentation. The study aims first to conceptualise and set up library information and create a comprehensive database of MALDI-TOF-MS spectra from environmental water samples. The samples were analysed over a year (2021-2022) using membrane filtration methodology (0.45 μm and 0.22 μm) and then isolated on R2A agar for a period of 5 days and Yeast extract agar growing at 22 °C up to 4 days and 37 °C for 48 hours. The undetected organisms by MALDI-TOF-MS were analysed by PCR and then sequenced. The information obtained by the sequencing was further implemented in the MALDI-TOF-MS library. Among the culturable bacteria, the results show how the incubator temperature affects the growth of some genera instead of others, as demonstrated by Pseudomonas sp., which grows at 22 °C, compared to Bacillus sp., which is abundant at 37 °C. The bacteria community shows a variation in composition also between the media used, as demonstrated with R2A agar which has been defined by a higher presence of organisms not detected compared to YEA. Interesting is the variability of the Genus over one year of sampling and how the seasonality impacts the bacteria community; in fact, in some sampling locations, we observed how the composition changed, moving from winter to spring and summer. In conclusion, the bacteria community in groundwater and river bank filtration represents important information that needs to be added to the library to simplify future water quality analysis but mainly to prevent potential risks to human health.

Keywords: water quality, MALDI-TOF-MS, sequencing, library

Procedia PDF Downloads 64

Authors: K. Shimola, M. Krishnaveni

Abstract:

This paper examines vulnerability assessment of water resources in a semi-arid basin using the 4-step approach. The vulnerability assessment framework is developed to study the water resources vulnerability which includes the creation of GIS-based vulnerability maps. These maps represent the spatial variability of the vulnerability index. This paper introduces the 4-step approach to assess vulnerability that incorporates a new set of indicators. The approach is demonstrated using a framework composed of a precipitation data for (1975–2010) period, temperature data for (1965–2010) period, hydrological model outputs and the water resources GIS data base. The vulnerability assessment is a function of three components such as exposure, sensitivity and adaptive capacity. The current water resources vulnerability is assessed using GIS based spatio-temporal information. Rainfall Coefficient of Variation, monsoon onset and end date, rainy days, seasonality indices, temperature are selected for the criterion ‘exposure’. Water yield, ground water recharge, evapotranspiration (ET) are selected for the criterion ‘sensitivity’. Type of irrigation and storage structures are selected for the criterion ‘Adaptive capacity’. These indicators were mapped and integrated in GIS environment using overlay analysis. The five sub-basins, namely Arjunanadhi, Kousiganadhi, Sindapalli-Uppodai and Vallampatti Odai, fall under medium vulnerability profile, which indicates that the basin is under moderate stress of water resources. The paper also explores prioritization of sub-basinwise adaptation strategies to climate change based on the vulnerability indices.

Keywords: adaptive capacity, exposure, overlay analysis, sensitivity, vulnerability

Procedia PDF Downloads 296

Authors: Hui-Chen Tsai, Chien-Jen Ho, Bo-Wei Power Liang, Ying Shen, Yi-Hsin Lai

Abstract:

Former Taiwan Metal Mining Corporation and its associated 3 wasted flue gas tunnels, hereinafter referred to as 'TMMC', was contaminated with heavy metals, Polychlorinated biphenyls (PCBs) and Total Petroleum Hydrocarbons (TPHs) in soil. Since the contamination had been exposed and unmanaged in the environment for more than 40 years, the extent of the contamination area is estimated to be more than 25 acres. Additionally, TMMC is located in a remote, mountainous area where almost no residents are residing in the 1-km radius area. Thus, it was deemed necessary to conduct an ecological risk assessment in order to evaluate the details of future contaminated site management plan. According to the winter and summer, ecological investigation results, one type of endangered, multiple vulnerable and near threaten plant was discovered, as well as numerous other protected species, such as Crested Serpent Eagle, Crested Goshawk, Black Kite, Brown Shrike, Taiwan Blue Magpie were observed. Ecological soil screening level (Eco-SSLs) developed by USEPA was adopted as a reference to conduct screening assessment. Since all the protected species observed surrounding TMMC site were birds, screening ecological risk assessment was conducted on birds only. The assessment was assessed mainly based on the chemical evaluation, which the contamination in different environmental media was compared directly with the ecological impact levels (EIL) of each evaluation endpoints and the respective hazard quotient (HQ) and hazard index (HI) could be obtained. The preliminary ecological risk assessment results indicated HI is greater than 1. In other words, the biological stressors (birds) were exposed to the contamination, which was already exceeded the dosage that could cause unacceptable impacts to the ecological system. This result was mainly due to the high concentration of arsenic, metal and lead; thus it was suggested the above mention contaminants should be remediated as soon as possible or proper risk management measures should be taken.

Keywords: screening, ecological risk assessment, ecological impact levels, risk management

Procedia PDF Downloads 111

Authors: Rajashree Naik, Laxmi Kant Sharma

Abstract:

Sambhar lake is the largest inland Salt Lake of India, declared as a Ramsar site on 23 March 1990. Due to high salinity and alkalinity condition its biodiversity richness is contributed by haloalkaliphilic flora and fauna along with the diverse land cover including waterbody, wetland, salt crust, saline soil, vegetation, scrub land and barren land which welcome large number of flamingos and other migratory birds for winter harboring. But with the gradual increase in the irrational salt extraction activities, the ecological diversity is at stake. There is an urgent need to assess the ecosystem. Advanced technology like remote sensing and GIS has enabled to look into the past, compare with the present for the future planning and management of the natural resources in a judicious way. This paper is a research work intended to present a vegetation in typical inland lake environment of Sambhar wetland using satellite data of NASA’s EO-1 Hyperion sensor launched in November 2000. With the spectral range of 0.4 to 2.5 micrometer at approximately 10nm spectral resolution with 242 bands 30m spatial resolution and 705km orbit was used to produce a vegetation map for a portion of the wetland. The vegetation map was tested for classification accuracy with a pre-existing detailed GIS wetland vegetation database. Though the accuracy varied greatly for different classes the algal communities were successfully identified which are the major sources of food for flamingo. The results from this study have practical implications for uses of spaceborne hyperspectral image data that are now becoming available. Practical limitations of using these satellite data for wetland vegetation mapping include inadequate spatial resolution, complexity of image processing procedures, and lack of stereo viewing.

Keywords: Algal community, NASA’s EO-1 Hyperion, salt-tolerant species, wetland vegetation mapping

Procedia PDF Downloads 109

Authors: Malik Abid Hussain Khokhar, Muhammad Adnan Tahir, Hisham Bin Hafeez Awan

Abstract:

Continuous environmental determinism and climatic change in the entire globe due to increasing land surface temperature (LST) has become a vital phenomenon nowadays. LST is accelerating because of increasing greenhouse gases in the environment which results of melting down ice caps, ice sheets and glaciers. It has not only worse effects on vegetation and water bodies of the region but has also severe impacts on monsoon areas in the form of capricious rainfall and monsoon failure extensive precipitation. Environment can be monitored with the help of various geographic information systems (GIS) based algorithms i.e. SC (Single), DA (Dual Angle), Mao, Sobrino and SW (Split Window). Estimation of LST is very much possible from digital image processing of satellite imagery. This paper will encompass extraction of LST of Abbottabad using SW technique of GIS and Remote Sensing over last ten years by means of Landsat 7 ETM+ (Environmental Thematic Mapper) and Landsat 8 vide their Thermal Infrared (TIR Sensor) and Optical Land Imager (OLI sensor less Landsat 7 ETM+) having 100 m TIR resolution and 30 m Spectral Resolutions. These sensors have two TIR bands each; their emissivity and spectral radiance will be used as input statistics in SW algorithm for LST extraction. Emissivity will be derived from Normalized Difference Vegetation Index (NDVI) threshold methods using 2-5 bands of OLI with the help of e-cognition software, and spectral radiance will be extracted TIR Bands (Band 10-11 and Band 6 of Landsat 7 ETM+). Accuracy of results will be evaluated by weather data as well. The successive research will have a significant role for all tires of governing bodies related to climate change departments.

Keywords: environment, Landsat 8, SW Algorithm, TIR

Procedia PDF Downloads 342

Authors: Morteza Naderi

Abstract:

The Persian fallow deer was considered as a globally extinct species until 1956 when a small population was rediscovered from Dez Wildlife Refuge and Karkheh Wildlife Refuge in southwestern parts of Iran. After long species rehabilitation process, the species was transplanted to Dasht-e-Naz Wildlife Refuge in northern Iran, and from where, follow deer was introduced to the different selected habitats such as Ashk Island in Lake Uromiyeh National Park. During 12 years, (from 1978 to 1989) 58 individuals (25 males and 33 females) were transferred to Ask Island. The main threat to the established population was related to the freshwater shortage and existing just one single trough such as high mortality rate of adult males during rutting season, snake biting and dilutional hyponatremia. Desiccation of Lake Uromiyeh in recent years raised new challenges to the conservation process, as about 80 individuals, nearly one third of the population were died in 2011. Connection of Island to the mainland caused predators’ accessibility (such as wolf and Jackal) to the Ask Island and higher mortality because of follow deer attraction to the surrounding mainland farms. Conservation team faced such new challenges that may cause introduction plan to be probably failed. Investigations about habitat affinities and carrying capacity are the main basic researches in the management and conservation of the species. Logistic regression analysis showed that the presence of the different fresh water resources as well as Allium akaka and Pistacia atlantica are the main environmental variables affect Follow deer habitat selection. Habitat carrying capacity analysis both in summer and winter seasons indicated that Ashk Island can support 240±30 of Persian follow deer.

Keywords: carrying capacity, follow deer, lake Uromiyeh, microhabitat affinities, population oscillation, predation, sex ratio

Procedia PDF Downloads 309

Authors: P. Defossez, J. M. Bonnefond, D. Garrigou, P. Trichet, F. Danjon

Abstract:

Windstorm damage to European forests has ecological, social and economic consequences of major importance. Most trees during storms are uprooted. While a large amount of work has been done over the last decade on understanding the aerial tree response to turbulent wind flow, much less is known about the root-soil interface, and the impact of soil moisture and root-soil system fatiguing on tree uprooting. Anchorage strength is expected to be reduced by water-logging and heavy rain during storms due to soil strength decrease with soil water content. Our paper is focused on the maritime pine cultivated on sandy soil, as a representative species of the Forêt des Landes, the largest cultivated forest in Europe. This study aims at providing knowledge on the effects of soil saturation on root anchorage. Pulling experiments on trees were performed to characterize the resistance to wind by measuring the critical bending moment (Mc). Pulling tests were performed on 12 maritime pines of 13-years old for two unsaturated soil conditions that represent the soil conditions expected in winter when wind storms occur in France (w=11.46 to 23.34 % gg⁻¹). A magnetic field digitizing technique was used to characterize the three-dimensional architecture of root systems. The soil mechanical properties as function of soil water content were characterized by laboratory mechanical measurements as function of soil water content and soil porosity on remolded samples using direct shear tests at low confining pressure ( < 15 kPa). Remarkably Mc did not depend on w but mainly on the root system morphology. We suggested that the importance of soil water conditions on tree anchorage depends on the tree size. This study gives a new insight on young tree anchorage: roots may sustain by themselves anchorage, whereas adhesion between roots and surrounding soil may be negligible in sandy soil.

Keywords: roots, sandy soil, shear strength, tree anchorage, unsaturated soil

Procedia PDF Downloads 271

Authors: Cynthia G. Esquerre, Amparo Iris Zavaleta

Abstract:

Extremophiles constitute a potentially valuable source of proteases for the development of biotechnological processes; however, the number of available studies in the literature is limited compared to mesophilic counterparts. Therefore, in this study, Peruvian halophilic microorganisms were characterized to select suitable proteolytic strains that produce active proteases under exigent conditions. Proteolysis was screened using the streak plate method with gelatin or skim milk as substrates. After that, proteolytic microorganisms were selected for phenotypic characterization and screened by a semi-quantitative proteolytic test using a modified method of diffusion agar. Finally, proteolysis was evaluated using partially purified extracts by ice-cold ethanol precipitation and dialysis. All analyses were carried out over a wide range of NaCl concentrations, pH, temperature and substrates. Of a total of 60 strains, 21 proteolytic strains were selected, of these 19 were extreme halophiles and 2 were moderates. Most proteolytic strains demonstrated differences in their biochemical patterns, particularly in sugar fermentation. A total of 14 microorganisms produced extracellular proteases, 13 were neutral, and one was alkaline showing activity up to pH 9.0. Proteases hydrolyzed gelatin as the most specific substrate. In general, catalytic activity was efficient under a wide range of NaCl (1 to 4 M NaCl), temperature (37 to 55 °C) and after an ethanol exposition performed at -20 °C for 24 hours. In conclusion, this study reported 14 candidates extremely halophiles producing extracellular proteases capable of being stable and active on a wide range of NaCl, temperature and even long lasting ethanol exposition.

Keywords: biotechnological processes, ethanol exposition, extracellular proteases, extremophiles

Procedia PDF Downloads 268

Authors: Lavanya Annadi, Fahimeh Jafari

Abstract:

Transportation brings immense benefits to society, but it also has its costs. Costs include such as the cost of infrastructure, personnel and equipment, but also the loss of life and property in traffic accidents on the road, delays in travel due to traffic congestion and various indirect costs in terms of air transport. More research has been done to identify the various factors that affect road accidents, such as road infrastructure, traffic, sociodemographic characteristics, land use, and the environment. The aim of this research is to predict the probabilistic crash prediction of vehicles using machine learning due to natural and structural reasons by excluding spontaneous reasons like overspeeding etc., in the United States. These factors range from weather factors, like weather conditions, precipitation, visibility, wind speed, wind direction, temperature, pressure, and humidity to human made structures like road structure factors like bump, roundabout, no exit, turning loop, give away, etc. Probabilities are dissected into ten different classes. All the predictions are based on multiclass classification techniques, which are supervised learning. This study considers all crashes that happened in all states collected by the US government. To calculate the probability, multinomial expected value was used and assigned a classification label as the crash probability. We applied three different classification models, including multiclass Logistic Regression, Random Forest and XGBoost. The numerical results show that XGBoost achieved a 75.2% accuracy rate which indicates the part that is being played by natural and structural reasons for the crash. The paper has provided in-deep insights through exploratory data analysis.

Keywords: road safety, crash prediction, exploratory analysis, machine learning

Procedia PDF Downloads 90

Authors: Ibrahim Khan, Waqas Khalid

Abstract:

The Healthcare sector is known to consume a higher proportion of total energy consumption in the HVAC market owing to an excessive cooling and heating requirement in maintaining human thermal comfort in indoor conditions, catering to patients undergoing treatment in hospital wards, rooms, and intensive care units. The indoor thermal comfort conditions in selected hospitals of Islamabad, Pakistan, were measured on a real-time basis with the collection of first-hand experimental data using calibrated sensors measuring Ambient Temperature, Wet Bulb Globe Temperature, Relative Humidity, Air Velocity, Light Intensity and CO2 levels. The Experimental data recorded was analyzed in conjunction with the Thermal Comfort Questionnaire Surveys, where the participants, including patients, doctors, nurses, and hospital staff, were assessed based on their thermal sensation, acceptability, preference, and comfort responses. The Recorded Dataset, including experimental and survey-based responses, was further analyzed in the development of a correlation between operative temperature, operative relative humidity, and other measured operative parameters with the predicted mean vote and adaptive predicted mean vote, with the adaptive temperature and adaptive relative humidity estimated using the seasonal data set gathered for both summer – hot and dry, and hot and humid as well as winter – cold and dry, and cold and humid climate conditions. The Machine Learning Logistic Regression Algorithm was incorporated to train the operative experimental data parameters and develop a correlation between patient sensations and the thermal environmental parameters for which a new ML-based adaptive thermal comfort model was proposed and developed in our study. Finally, the accuracy of our model was determined using the K-fold cross-validation.

Keywords: predicted mean vote, thermal comfort, energy management, logistic regression, machine learning

Procedia PDF Downloads 38

Authors: Md. Kumruzzaman, Anutosh Das, Md. Mosharraf Hossain

Abstract:

Historically, rapid urban growth activities are considered one of the main culprits behind urban floods or waterlogging. The increased unplanned urbanization of many areas of Dhaka has resulted in waterlogging, urban floods, and increasing groundwater depth. To determine potential groundwater recharge from precipitation, the study is being conducted to examine the changes in land use/land cover (LULC) and urban runoff extent based on the NRCS-CN from 2005–2021. Four kinds of land use are used to examine the LULC change: built-up, bare land, vegetation, and water body. These categories are used for the years 2005, 2010, 2015, and 2021. The built-up area is growing at a relatively fast rate: 7.43%, 17.4%, and 5.21%, respectively, between the years 2005 and 2010, 2010 and 2015, and 2015 and 2021. As the amount of impervious surface rose in Dhaka city, stormwater discharge increased from 2005 to 2021. In 2005, 2010, 2015, and 2021, heavy stormwater runoff regions made up around 24.873%, 32.616%, 49.118%, and 55.986% of the entire Dhaka city. Stormwater runoff accounted for around 53.738%, 55.092%, 63.472%, and 67.061% of the total rainfall in 2005, 2010, 2015, and 2021, respectively. Between 2005 and 2021, a significant portion of the natural land cover was altered because of the expanding impervious surface, which also harmed the natural drainage system. Due to careless growth, the potential for stormwater runoff and groundwater recharge in Dhaka city worsens every year. Concerning this situation, a sustainable urban drainage system (SUDS) can be the best possible solution for minimizing the stormwater runoff and groundwater recharge problem.

Keywords: LULC, impervious surface, stormwater runoff, groundwater recharge, SUDS

Procedia PDF Downloads 60

Authors: Yinsheng Zhang

Abstract:

Changes in the extent and amount of snow cover in Eurasia are of great interest because of their vital impacts on the global climate system and regional water resource management. This study investigated the spatial and temporal variability of the snow cover extent (SCE) and snow water equivalent (SWE) of continental Eurasia using the Northern Hemisphere Equal-Area Scalable Earth Grid (EASE-Grid) Weekly SCE data for 1972–2006 and the Global Monthly EASE-Grid SWE data for 1979–2004. The results indicated that, in general, the spatial extent of snow cover significantly decreased during spring and summer, but varied little during autumn and winter over Eurasia in the study period. The date at which snow cover began to disappear in spring has significantly advanced, whereas the timing of snow cover onset in autumn did not vary significantly during 1972–2006. The snow cover persistence period declined significantly in the western Tibetan Plateau as well as the partial area of Central Asia and northwestern Russia but varied little in other parts of Eurasia. ‘Snow-free breaks’ (SFBs) with intermittent snow cover in the cold season were mainly observed in the Tibetan Plateau and Central Asia, causing a low sensitivity of snow cover persistence period to the timings of snow cover onset and disappearance over the areas with shallow snow. The averaged SFBs were 1–14 weeks in the Tibetan Plateau during 1972–2006 and the maximum intermittence could reach 25 weeks in some extreme years. At a seasonal scale, the SWE usually peaked in February or March but fell gradually since April across Eurasia. Both annual mean and annual maximum SWE decreased significantly during 1979–2004 in most parts of Eurasia except for eastern Siberia as well as northwestern and northeastern China.

Keywords: Eurasia, snow cover extent, snow cover persistence period, snow-free breaks, onset and disappearance timings, snow water equivalent

Procedia PDF Downloads 126