Topic Review
 Aspergillus and Penicillium Species in Biodegradation of Pesticides
Since filamentous fungi of Penicillium and Aspergillus genera can colonize very diverse niches, and Ascomycota seems to be the dominant phylum within the microbial group in various contaminated substrates, they possess great potential in the remediation of pesticide-contaminated sites. Different species can remove the pesticides at different rates, and to various extents; however, the fungal ability to resist high concentrations of pesticides is almost unparalleled compared to other microbial groups. Their performance may be further improved by applying indigenous strains isolated from pesticide-contaminated soils and sediments. 
  • 192
  • 10 Jul 2023
Topic Review
100,000-Year Problem
The 100,000-year problem ("100 ky problem", "100 ka problem") of the Milankovitch theory of orbital forcing refers to a discrepancy between the reconstructed geologic temperature record and the reconstructed amount of incoming solar radiation, or insolation over the past 800,000 years. Due to variations in the Earth's orbit, the amount of insolation varies with periods of around 21,000, 40,000, 100,000, and 400,000 years. Variations in the amount of incident solar energy drive changes in the climate of the Earth, and are recognised as a key factor in the timing of initiation and termination of glaciations. While there is a Milankovitch cycle in the range of 100,000 years, related to Earth's orbital eccentricity, its contribution to variation in insolation is much smaller than those of precession and obliquity. The 100,000-year-problem refers to the lack of an obvious explanation for the periodicity of ice ages at roughly 100,000 years for the past million years, but not before, when the dominant periodicity corresponded to 41,000 years. The unexplained transition between the two periodicity regimes is known as the Mid-Pleistocene Transition, dated to some 800,000 years ago. The related "400,000-year-problem" refers to the absence of a 400,000-year periodicity due to orbital eccentricity in the geological temperature record over the past 1.2 million years. The transition in periodicity from 41,000 years to 100,000 years can now be reproduced in numerical simulations that include a decreasing trend in carbon dioxide and glacially induced removal of regolith, as explained in more detail in the article Mid-Pleistocene Transition.
  • 711
  • 08 Oct 2022
Topic Review
4.2 Kiloyear Event
The 4.2-kiloyear BP aridification event was one of the most severe climatic events of the Holocene epoch. It defines the beginning of the current Meghalayan age in the Holocene epoch. Starting around 2200 BC, it probably lasted the entire 22nd century BC. It has been hypothesised to have caused the collapse of the Old Kingdom in Egypt as well as the Akkadian Empire in Mesopotamia, and the Liangzhu culture in the lower Yangtze River area. The drought may also have initiated the collapse of the Indus Valley Civilisation, with some of its population moving southeastward to follow the movement of their desired habitat, as well as the migration of Indo-European-speaking people into India. Some scientists disagree with this conclusion and point out that the event was neither a global drought nor did it happen in a clear timeline.
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  • 04 Nov 2022
Topic Review
4D-Based Environmental Impact Analysis of Road Project Variants
Road construction work has a multitude of impacts on its host environment, and the effect of these impacts varies according to the areas it crosses. Taking these impacts into account from the earliest stages of project planning is the ideal approach pursued by planners to ensure that their plans not only take these impacts into account but also mitigate their effects as much as possible. Drawing up a project schedule that considers the impact of the work requires an in-depth understanding of its scale, spatial extent, and timing. 
  • 145
  • 06 Nov 2023
Topic Review
5G for Climate Change Control
Climate change is one of the most challenging problems that humanity has ever faced. With the rapid development in technology, a key feature of 5G networks is the increased level of connectivity between everyday objects, facilitated by faster internet speeds with smart facilities indicative of the forthcoming 5G-driven revolution in Internet of Things (IoT).
  • 1.2K
  • 11 Jan 2022
Topic Review
A Focus on Active Chemicals in Sub-Saharan Africa
Active chemicals are among the contaminants of emerging concern that are rarely covered in regulatory documents in sub-Saharan Africa. 
  • 682
  • 31 Dec 2021
Topic Review
Abandoned Croplands in South Africa
There is no standardised definition of agricultural land abandonment; however, a simple definition is the cessation of agricultural activities on a given surface of land. The term agricultural land abandonment is inclusive of land previously used for crops, vegetables, fruit trees, and cultivated and natural pastures. Other agricultural land abandonment studies specifically focus on crops, hence terms such as cropland abandonment, formerly arable lands, and old arable lands or fields are used. Others specify that for the land to qualify as abandoned, it should not be used for any other activity such as urbanisation or afforestation. Therefore, in the context of the rural areas of Africa wherein the cessation of cropping the land is used for grazing, the definition of cropland abandonment suffices. Baxter and Calvert define cropland abandonment as a process of withdrawing cropland from active agricultural production without a plan for crop cultivation in the immediate future. The cessation is usually due to a decline in economic viability even after changes in farming practices. Cessation results in natural succession wherein grasses, shrubs, and trees colonise former cropping lands; it can also result in land degradation. In the former homeland communal areas of South Africa, where the main agricultural activity involves cropping and livestock production, by default if the land is not used for cropping it turns into a grazing area. The same trend of abandoned cropping lands being used for grazing was also reported in Botswana. Therefore, the definition of abandoned cropping land is land mainly used for grazing. The areas are sometimes also called old fields, fallow, or idle fields. Some have turned to be secondary grasslands.
  • 2.0K
  • 25 May 2022
Topic Review
Abundance of Mycoplankton and Its Ecological Role
Mycoplankton are saprophytic organisms in plankton communities in marine and freshwater ecosystems. They consist of filamentous free-living fungi and yeasts associated with planktonic particles or phytoplankton. Similar to planktonic bacteria, these aquatic fungi play important roles in heterotrophic mineralization and nutrient cycling. Planktonic bacteria can be up to 20 mm in diameter and over 50 mm in length
  • 570
  • 23 May 2022
Topic Review
Achieving Environmental Sustainability in Africa
The concept of sustainability requires that the production of goods and services fulfills present demands without jeopardizing the potential to satisfy the needs of future generations. The environment is a finite resource; a healthy environment benefits the ecosystem and all life. Therefore, to sustain the planet, the ecosystem, and all life on it, it is critical that environmental resources be appropriately managed and preserved. Fighting environmental degradation has been a key priority for advanced and emerging countries. Environmental degradation has posed a danger to the economic well-being of the entire world, as it is linked to the success of various macroeconomic factors.
  • 734
  • 27 Jul 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.
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  • 15 Nov 2022
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