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Topic Review
Smart Systems and IoT for Aquaponics Automation
Aquaponics is an innovative, smart, and sustainable agricultural technology that integrates aquaculture (farming of fish) with hydroponics in growing vegetable crops symbiotically. The correct implementation of aquaponics helps in providing healthy organic foods with low consumption of water and chemical fertilizers. Numerous research attempts have been directed toward real implementations of this technology feasibly and reliably at large commercial scales and adopting it as a new precision technology. For better management of such technology, there is an urgent need to use the Internet of things (IoT) and smart sensing systems for monitoring and controlling all operations involved in the aquaponic systems.
  • 5.7K
  • 11 Aug 2022
Topic Review
Bioremediation Techniques
Bioremediation is a process that uses biological organisms to remove or re-treat an environmental pollutant through metabolic processes and plants to eradicate hazardous pollutants and restore the ecosystem to its original condition.
  • 5.7K
  • 24 Apr 2023
Topic Review
Food Security
Food security is a measure of the availability of food and individuals' ability to access it. Affordability is only one factor. There is evidence of food security being a concern many thousands of years ago, with central authorities in ancient China and ancient Egypt being known to release food from storage in times of famine. At the 1974 World Food Conference the term "food security" was defined with an emphasis on supply. They said food security is the "availability at all times of adequate, nourishing, diverse, balanced and moderate world food supplies of basic foodstuffs to sustain a steady expansion of food consumption and to offset fluctuations in production and prices". Later definitions added demand and access issues to the definition. The final report of the 1996 World Food Summit states that food security "exists when all people, at all times, have physical and economic access to sufficient, safe and nutritious food to meet their dietary needs and food preferences for an active and healthy life." Household food security exists when all members, at all times, have access to enough food for an active, healthy life. Individuals who are food secure do not live in hunger or fear of starvation. Food insecurity, on the other hand, is defined by the United States Department of Agriculture (USDA) as a situation of "limited or uncertain availability of nutritionally adequate and safe foods or limited or uncertain ability to acquire acceptable foods in socially acceptable ways". Food security incorporates a measure of resilience to future disruption or unavailability of critical food supply due to various risk factors including droughts, shipping disruptions, fuel shortages, economic instability, and wars. In the years 2011–2013, an estimated 842 million people were suffering from chronic hunger. The Food and Agriculture Organization of the United Nations, or FAO, identified the four pillars of food security as availability, access, utilization, and stability. The United Nations (UN) recognized the Right to Food in the Declaration of Human Rights in 1948, and has since said that it is vital for the enjoyment of all other rights. The 1996 World Summit on Food Security declared that "food should not be used as an instrument for political and economic pressure".
  • 5.5K
  • 16 Nov 2022
Topic Review
Greenery Systems
Urbanization, when it is not planned carefully, are highly effecting the urban heat island. To mitigate the problem, urbanization planning must take into consideration the implementation of greenery systems and sustainable ecosystems for buildings as part of the solution in addition to the outer space. The mitigation techniques that are influencing the urban heat index may be the greenery systems applied on buildings, or urban green spaces that include large land and large scale systems, such as lakes and parks. The objective of the current article is to compile, discusses and compare the previous studies on greenery systems, like green roofs and green walls, how they are supporting the energy saving and improve thermal conditions in the building sector, as well as improving the urban heat index. The fundamental  of greenery systems, which are thermal insulation, evapotranspiration, and shading effect, are also discussed. The benefits of greenery systems are including the improvement of stormwater management,  improvement of air quality, the reduction of sound pollution, the reduction of carbon dioxide, and the improvement of aesthetic building value. 
  • 5.5K
  • 29 Oct 2020
Topic Review
Metal Sulfide Precipitation
Metal sulfide precipitation can efficiently recover several metals and metalloids from different aqueous sources, including wastewaters and hydrometallurgical solutions. 
  • 5.5K
  • 04 Jan 2022
Topic Review
Polymers in Wastewater Treatment
The utilization of various types of natural and modified polymers for removing toxicant dyes in wastewater generated by the dye industry is reviewed in this article. Dye wastewater contains large amounts of metals, surfactants, and organic matter, which have adverse effects on human health, potentially causing skin diseases and respiratory problems. The removal of dyes from wastewaters through chemical and physical processes has been addressed by many researchers. Currently, the use of natural and modified polymers for the removal of dyes from wastewater is becoming more common. Although modified polymers are preferred for the removal of dyes, due to their biodegradability and non-toxic nature, large amounts of polymers are required, resulting in higher costs. 
  • 5.4K
  • 20 Oct 2020
Topic Review
Ordovician–Silurian Extinction Events
The Ordovician–Silurian extinction events, when combined, are the second-largest of the five major extinction events in Earth's history in terms of percentage of genera that became extinct. This event greatly affected marine communities, which caused the disappearance of one third of all brachiopod and bryozoan families, and further numerous groups of conodonts, trilobites, and graptolites. The Ordovician–Silurian extinction occurred during the Hirnantian stage of the Ordovician Period and the subsequent Rhuddanian stage of the Silurian Period. The last event, the Late Ordovician mass extinction (LOME), is dated in the interval of 455 to 430 million years ago, lasting from the Middle Ordovician to Early Silurian, thus including the extinction period. This event was the first of the big five Phanerozoic events and was the first to significantly affect animal-based communities. In May 2020, geologists reported that this mass extinction, the Late Ordovician mass extinction, 445 million years ago, may have been the result of global warming. Almost all major taxonomic groups were affected during this extinction event. Extinction was global during this period, eliminating 49–60% of marine genera and nearly 85% of marine species. Brachiopods, bivalves, echinoderms, bryozoans and corals were particularly affected. Before the late Ordovician cooling, temperatures were relatively warm and it is the suddenness of the climate changes and the elimination of habitats due to sea-level fall that are believed to have precipitated the extinctions. The falling sea level disrupted or eliminated habitats along the continental shelves. Evidence for the glaciation was found through deposits in the Sahara Desert. A combination of lowering of sea level and glacially driven cooling were likely driving agents for the Ordovician mass extinction.
  • 5.4K
  • 23 Oct 2022
Topic Review
Sustainable Valorization of Sugarcane Waste from Sugarcane Processing
Sugarcane is a lignocellulosic crop and the juice extracted from its stalks provides the raw material for 86% of sugar production. Globally, sugarcane processing to obtain sugar and/or ethanol generates more than 279 million tons of solid and liquid waste annually, as well as by-products; namely, straws, bagasse, press mud, wastewater, ash from bagasse incineration, vinasse from ethanol distillation, and molasses. If not properly managed, this waste will pose risks to both environmental factors and human health. Valorization of waste has gained momentum, having an important contribution to the fulfillment of policies and objectives related to sustainable development and circular bioeconomy. Various technologies are well-established and implemented for the valorization of waste and by-products from sugarcane processing, while other innovative technologies are still in the research and development stage, with encouraging prospects.
  • 5.3K
  • 19 Sep 2022
Topic Review
Sustainable Tourism in Fiji
The tourism industry has evolved as a major contributor to economic development and employment creation globally. Over the past seven decades, the tourism industry has experienced growth in both developed and developing countries. Although tourism has significant economic benefits, it often compromises environmental quality. Thus, tourism sustainability becomes an important element in managing the industry. Tourism sustainability has emerged as a leading policy paradigm and is important because tourism is a significant contributor to carbon emissions worldwide.
  • 5.3K
  • 02 Jun 2022
Topic Review
Acid Rain
Acid rain has an acidity that is higher than that of normal rainwater. Normal rainwater is not neutral (which would be pH 7) but slightly acidic (it has a pH < 5.5), because some of the carbon dioxide CO2 dissolved in the water is present as carbonic acid H2CO3. In acid rain, chemicals from pollution and natural causes such as volcanic eruptions and emissions from vegetation increase the acidity of the water to as low as pH 4.4 to 4 (as measured in the 1990s in various places). Such acidic rainwater is dangerous for people, vegetation, water bodies including the oceans and its inhabitants, buildings and soil. Since the pH scale is logarithmic, a change from 5.5 to 4.5 means a tenfold increase in acidity. The three main pollutants that cause acid rain are the nitric oxides NO and NO2 (summarized as NOx) and sulfur dioxide SO2. These substances react with water to nitric acid HNO3 and sulfuric acid H2SO4. In the 1980s, in nearly all of Northern Europe and in the Northern United States, suddenly and unexpectedly, whole forests began to die (this effect got to be known as forest dieback). German forests especially experienced severe damage: from 8% in 1982 it increased to 50% in 1984, and stayed as such till 1987. The damage occurred amongst various tree species. Researchers established connections of this damage to acid rain. The mandatory installment of sulfur filters in coal power plants and of catalytic converters in cars in various industrialized countries reduced air pollution with the chemicals related to the formation of acid rain, and, although the forests are still not in perfect shape (about 20% are heavily impaired) a complete death was prevented.
  • 5.2K
  • 15 Nov 2022
Topic Review
Late Devonian Extinction
The Late Devonian extinction was one of five major extinction events in the history of life on Earth. A major extinction, the Kellwasser event, occurred at the boundary that marks the beginning of the last phase of the Devonian period, the Famennian faunal stage (the Frasnian–Famennian boundary), about 376–360 million years ago. Overall, 19% of all families and 50% of all genera became extinct. A second, distinct mass extinction, the Hangenberg event, closed the Devonian period. Although it is clear that there was a massive loss of biodiversity in the Late Devonian, the timespan of this event is uncertain, with estimates ranging from 500,000 to 25 million years, extending from the mid-Givetian to the end-Famennian. Nor is it clear whether there were two sharp mass extinctions or a series of smaller extinctions, though the latest research suggests multiple causes and a series of distinct extinction pulses during an interval of some three million years. Some consider the extinction to be as many as seven distinct events, spread over about 25 million years, with notable extinctions at the ends of the Givetian, Frasnian, and Famennian stages. By the Late Devonian, the land had been colonized by plants and insects. In the oceans were massive reefs built by corals and stromatoporoids. Euramerica and Gondwana were beginning to converge into what would become Pangaea. The extinction seems to have only affected marine life. Hard-hit groups include brachiopods, trilobites, and reef-building organisms; the reef-building organisms almost completely disappeared. The causes of these extinctions are unclear. Leading hypotheses include changes in sea level and ocean anoxia, possibly triggered by global cooling or oceanic volcanism. The impact of a comet or another extraterrestrial body has also been suggested, such as the Siljan Ring event in Sweden. Some statistical analysis suggests that the decrease in diversity was caused more by a decrease in speciation than by an increase in extinctions. This might have been caused by invasions of cosmopolitan species, rather than by any single event. Surprisingly, jawed vertebrates seem to have been unaffected by the loss of reefs or other aspects of the Kellwasser event, while agnathans were in decline long before the end of the Frasnian.
  • 5.2K
  • 30 Nov 2022
Topic Review
Applications of Ant Colony Optimization
Ant-inspired metaheuristic algorithms known as ant colony optimization (ACO) offer an approach that has the ability to solve complex problems in both discrete and continuous domains. ACOs have gained significant attention in the field of water resources management, since many problems in this domain are non-linear, complex, challenging and also demand reliable solutions. 
  • 5.2K
  • 10 May 2023
Topic Review
Satellite-Based Active Fire Detection
Detection of an active wildfire in a satellite image scene relies on an accurate estimation of the background temperature of the scene, which must be compared to the observed temperature, to decide on the presence of fire. The expected background temperature of a pixel is commonly derived based on spatial-contextual information. Multi-temporal information and multi-spectral information have also been exploited in estimation of the background temperature of a pixel. This review discusses different approaches of estimation of background temperature and highlights the potentiality of the estimation of the background temperature using the multi-temporal data for early fire detection and real-time fire monitoring. The perspectives of a proposed multi-temporal approach are also outlined. 
  • 5.2K
  • 06 Dec 2020
Topic Review
Soil Washing
Soil contamination with heavy metals and organic pollutants poses an environmental problem due to their persistence, bioaccumulation and toxicity. Soil washing is one of the most common remediation technologies for permanent removal of undesirable pollutants. The effectiveness of soil washing is affected by many factors such as soil geochemistry, pollutant characteristics, type and chemistry of washing agents, and processing conditions. A variety of washing agents have been tested in soil washing with their different effect on pollutant removal and on the overall quality of treated soil. Development of soil washing is based on searching for an inexpensive, readily-available and environmentally-friendly agents to remediate polluted soils. Despite the unquestionable effectiveness of soil washing, spent washing solutions are generated that need further treatment. This entry presents the principles and application of soil washing technology, as well as the examples of washing agents and methods for liquid waste treatment.  Soil washing is an ex-situ technology, including physical and/or chemical processes that aim to effectively remove pollutants from soil.
  • 5.0K
  • 08 Sep 2020
Topic Review
Spent Oil Bleaching Earths
Spent oil bleaching earth (SOBE) is a waste product obtained in the refining process of oil. It is estimated that 120 million tons of oil are processed with bleaching earth worldwide, generating 2.5 million tons of spent bleaching earth as residue. Moreover, the serious fire and contamination risks that arise during storage and disposal of spent bleaching earth require appropriate technical solutions. The current treatment of SOBE residue is not in line with the new circular economy policies promoted by the European Union, since in most cases it is disposed of in landfills. New technologies that allow oil recovery and treatment of the earths, aiming to convert them into useful products are then needed. 
  • 5.0K
  • 26 Jul 2021
Topic Review
Air pollution and Fuel Combustion
Air pollution is a precursor to many health issues such as difficulty breathing, asthma, lung and heart diseases, and cancer. 
  • 5.0K
  • 11 Jan 2022
Topic Review
Global Warming
Global warming is the ongoing rise of the average temperature of the Earth's climate system. It is a major aspect of climate change which, in addition to rising global surface temperatures, also includes its effects, such as changes in precipitation. While there have been prehistoric periods of global warming, observed changes since the mid-20th century have been unprecedented in rate and scale. The Intergovernmental Panel on Climate Change (IPCC) concluded that "human influence on climate has been the dominant cause of observed warming since the mid-20th century". These findings have been recognized by the national science academies of major nations and are not disputed by any scientific body of national or international standing. The largest human influence has been the emission of greenhouse gases, with over 90% of the impact from carbon dioxide and methane. Fossil fuel burning is the principal source of these gases, with agricultural emissions and deforestation also playing significant roles. Climate sensitivity to these gases is affected by feedbacks, such as loss of snow cover, increased water vapour, and melting permafrost. Land surfaces are heating faster than the ocean surface, leading to heat waves, wildfires, and the expansion of deserts. Increasing atmospheric energy and rates of evaporation are causing more intense storms and weather extremes, damaging infrastructure and agriculture. Surface temperature increases are greatest in the Arctic and have contributed to the retreat of glaciers, permafrost, and sea ice. Environmental impacts include the extinction or relocation of many species as their ecosystems change, most immediately in coral reefs, mountains, and the Arctic. Surface temperatures would stabilize and decline a little if emissions were cut off, but other impacts will continue for centuries, including rising sea levels from melting ice sheets, rising ocean temperatures, and ocean acidification from elevated levels of carbon dioxide. Mitigation efforts to address global warming include the development and deployment of low carbon energy technologies, policies to reduce fossil fuel emissions, reforestation, forest preservation, as well as the development of potential climate engineering technologies. Societies and governments are also working to adapt to current and future global warming impacts, including improved coastline protection, better disaster management, and the development of more resistant crops. Countries work together on climate change under the umbrella of the United Nations Framework Convention on Climate Change (UNFCCC), which has near-universal membership. The goal of the convention is to "prevent dangerous anthropogenic interference with the climate system". The IPCC has stressed the need to keep global warming below 1.5 °C (2.7 °F) compared to pre-industrial levels in order to avoid some irreversible impacts. With current policies and pledges, global warming by the end of the century is expected to reach about 2.8 °C (5.0 °F). At the current greenhouse gas (GHG) emission rate, the carbon budget for staying below 1.5 °C (2.7 °F) would be exhausted by 2028.
  • 5.0K
  • 12 Oct 2022
Topic Review
Production and Use of Typical Rubber Antioxidants
Antioxidants are prevalently used during rubber production to improve rubber performance, delay aging, and extend service life. Studies have revealed that their transformation products (TPs) could adversely affect environmental organisms and even lead to environmental events, which led to great public concern about environmental occurrence and potential impacts of rubber antioxidants and their TPs.
  • 5.0K
  • 22 Dec 2022
Topic Review
Pyrolysis and Gasification Mechanism of Biomass
Biomass can be converted to energy by using thermochemical and biochemical methodsecology; environmental; biomass; pyrolysis. Biochemical methods, including anaerobic digestion and fermentation, constitute the transformation of cellulose and hemicellulose into biofuel at the stages of hydrolysis and fermentation. At present, biochemical methods are cost-intensive, and involve problems with using lignin-rich biomass.
  • 4.9K
  • 26 Nov 2021
Topic Review
Odor Measurement Methods
Odor pollution related to industrial activities (e.g., chemical industries, oil and gas extraction and refining facilities, waste treatment and disposal facilities) is nowadays acknowledged as a serious environmental concern. Indeed, odors are currently subjected to control and regulation in many countries. Such regulations rely on the possibility of measuring odors. The methods that have been developed and standardized over the last years to measure odors, thereby including sensorial and instrumental techniques, are here described, thereby focusing on their applicability and limitations.
  • 4.8K
  • 08 Feb 2022
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