Topic Review
Climate Change (General Concept)
Climate change occurs when changes in Earth's climate system result in new weather patterns that remain in place for an extended period of time. This length of time can be as short as a few decades to as long as millions of years. Scientists have identified many episodes of climate change during Earth's geological history; more recently since the industrial revolution the climate has increasingly been affected by human activities driving global warming, and the terms are commonly used interchangeably in that context. The climate system receives nearly all of its energy from the sun. The climate system also gives off energy to outer space. The balance of incoming and outgoing energy, and the passage of the energy through the climate system, determines Earth's energy budget. When the incoming energy is greater than the outgoing energy, earth's energy budget is positive and the climate system is warming. If more energy goes out, the energy budget is negative and earth experiences cooling. The energy moving through Earth's climate system finds expression in weather, varying on geographic scales and time. Long-term averages and variability of weather in a region constitute the region's climate. Climate change is a long-term, sustained trend of change in climate. Such changes can be the result of "internal variability", when natural processes inherent to the various parts of the climate system alter the distribution of energy. Examples include variability in ocean basins such as the Pacific decadal oscillation and Atlantic multidecadal oscillation. Climate change can also result from external forcing, when events outside of the climate system's components nonetheless produce changes within the system. Examples include changes in solar output and volcanism. Climate change has various consequences for sea level changes, plant life, and mass extinctions; it also affects human societies.
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  • 14 Apr 2023
Topic Review
Urban Remote Sensing with Spatial Big Data
During the past decades, multiple remote sensing data sources, including nighttime light images, high spatial resolution multispectral satellite images, unmanned drone images, and hyperspectral images, among many others, have provided fresh opportunities to examine the dynamics of urban landscapes. In the meantime, the rapid development of telecommunications and mobile technology, alongside the emergence of online search engines and social media platforms with geotagging technology, has fundamentally changed how human activities and the urban landscape are recorded and depicted. The combination of these two types of data sources results in explosive and mind-blowing discoveries in contemporary urban studies, especially for the purposes of sustainable urban planning and development. Urban scholars are now equipped with abundant data to examine many theoretical arguments that often result from limited and indirect observations and less-than-ideal controlled experiments. For the first time, urban scholars can model, simulate, and predict changes in the urban landscape using real-time data to produce the most realistic results, providing invaluable information for urban planners and governments to aim for a sustainable and healthy urban future. 
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  • 14 Apr 2023
Topic Review
Processes Responsible for Nitrate Pollution in Water
Nitrate (NO3−) pollution of surface and groundwater bodies is a global problem of increasing concern, which has stimulated significant research interest. Nitrogen is crucial for life as a macronutrient for living organisms on Earth, but the global nitrogen cycle has been seriously altered by intensification of human activities, leading to eutrophication and hypoxic conditions of aquatic ecosystems. Due to nitrogen overfertilization, intensive agricultural practices generate huge nitrate fluxes that inadvertently deteriorate water quality. Different industrial processes also contribute to NO3− pollution in the environment. 
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  • 14 Apr 2023
Topic Review
Potential Alternative Resources for Rare Earth Elements
Seventeen elements in the periodic table including fifteen lanthanides (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) and Sc, as well as Y are often collectively referred to as rare earth elements (REE). The depleting REE ores and increasing mining costs are prompting us to consider alternative sources for these valuable metals, particularly from waste streams. Although REE concentrations in most of the alternative resources are lower than current REE ores, some sources including marine sediments, coal ash, and industrial wastes, such as red mud, are emerging as promising with significant concentrations of REE.
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  • 13 Apr 2023
Topic Review
Historical Greenhouse Gas Emission Trends in Saudi Arabia
The growth of population, gross domestic product (GDP), and urbanization have led to an increase in greenhouse gas (GHG) emissions in the Kingdom of Saudi Arabia (KSA). The leading GHG-emitting sectors are electricity generation, road transportation, cement, chemicals, refinery, iron, and steel.
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  • 12 Apr 2023
Topic Review
A Thermo-Catalytic Pyrolysis of Polystyrene Waste Review
Global polystyrene (PS) production has been influenced by the lightness and heat resistance this material offers in different applications, such as construction and packaging. However, population growth and the lack of PS recycling lead to a large waste generation, affecting the environment. Pyrolysis has been recognized as an effective recycling method, converting PS waste into valuable products in the chemical industry. The conversion of PS into a liquid with high aromatic content (84.75% of styrene) can be achieved by pyrolysis. In addition, PS favors the production of liquid fuel when subjected to co-pyrolysis with biomass, improving its properties such as viscosity and energy content. 
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  • 12 Apr 2023
Topic Review
Biorefinery of Sewage Sludge
The disposal of excess biological sewage sludge from wastewater treatment is a growing environmental issue due to the vast quantities generated worldwide. Due to its composition, sewage sludge could be potentially exploited as a renewable carbon source, rather than being considered an inevitable “nuisance” linked to the main task of wastewater treatment. Biorefinery encompasses any technology used to process excess biological sewage sludge (EBSS) for biofuel and/or resource recovery: proper process integration can contribute to generating multiple possible final products (energy and/or materials).
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  • 10 Apr 2023
Topic Review
Heavy Metals Biosorption by Algae
Seaweeds are mostly used in the wastewater treatment for removing toxic heavy metals.
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  • 10 Apr 2023
Topic Review
Green Conversion of Carbon Dioxide
Carbon capture and use may provide motivation for the global problem of mitigating global warming from substantial industrial emitters. Captured CO2 may be transformed into a range of products such as methanol as renewable energy sources. Polymers, cement, and heterogeneous catalysts for varying chemical synthesis are examples of commercial goods. Because some of these components may be converted into power, CO2 is a feedstock and excellent energy transporter. By employing collected CO2 from the atmosphere as the primary hydrocarbon source, a carbon-neutral fuel may be created. The fuel is subsequently burned, and CO2 is released into the atmosphere like a byproduct of the combustion process.
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  • 10 Apr 2023
Topic Review
Carbon Capture Technologies
With an increase in the global population and the subsequent rise in energy demands and waste generation, the rate of CO2 release is at a much faster rate than its recycling through photosynthesis or fixation, which increases its net accumulation in the atmosphere. A large amount of CO2 is emitted into the atmosphere from various sources such as the combustion of fossil fuels in power plants, vehicles and manufacturing industries. Thus, carbon capture plays a key role in the race to achieve net zero emissions, paving a path for a decarbonized economy. 
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  • 06 Apr 2023
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