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Topic Review
African Humid Period
The African humid period (AHP) is a climate period in Africa during the late Pleistocene and Holocene geologic epochs, when northern Africa was wetter than today. The covering of much of the Sahara desert by grasses, trees and lakes was caused by changes in Earth's orbit around the Sun; changes in vegetation and dust in the Sahara which strengthened the African monsoon; and increased greenhouse gases, which may, or may not imply that anthropogenic global warming could result in a shrinkage of the Sahara desert. During the preceding last glacial maximum, the Sahara contained extensive dune fields and was mostly uninhabited. It was much larger than today, but its lakes and rivers such as Lake Victoria and the White Nile were either dry or at low levels. The humid period began about 14,600–14,500 years ago at the end of Heinrich event 1, simultaneously to the Bølling-Allerød warming. Rivers and lakes such as Lake Chad formed or expanded, glaciers grew on Mount Kilimanjaro and the Sahara retreated. Two major dry fluctuations occurred; during the Younger Dryas and the short 8.2 kiloyear event. The African humid period ended 6,000–5,000 years ago during the Piora Oscillation cold period. While some evidence points to an end 5,500 years ago, in the Sahel, Arabia and East Africa the period appears to have taken place in several steps such as the 4.2 kiloyear event. The AHP led to a widespread settlement of the Sahara and the Arabian Deserts, and had a profound effect on African cultures, such as the birth of the Pharaonic civilization. They lived as hunter-gatherers until the agricultural revolution and domesticated cattle, goats and sheep. They left archeological sites and artifacts such as one of the oldest ships in the world, and rock paintings such as those in the Cave of Swimmers and in the Acacus Mountains. Earlier humid periods in Africa were postulated after the discovery of these rock paintings in now-inhospitable parts of the Sahara. When the period ended, humans gradually abandoned the desert in favour of regions with more secure water supplies, such as the Nile Valley and Mesopotamia, where they gave rise to early complex societies.
  • 3.6K
  • 10 Nov 2022
Topic Review
Agri-Environmental Indicators and Stakeholders’ Assessment of Their Quality
The degree to which economic goals have been prioritized over environmental and social objectives has caused dissatisfaction with conventional agricultural practices and stimulated the adoption of sustainable farming methods. One way to consider the multidimensionality of sustainable agriculture is to refer to indicators, more precisely, to agri-environmental indicators (AEIs). 
  • 355
  • 01 Apr 2022
Topic Review
Agricultural Big Data and Machine Learning
Sustainable agriculture is currently being challenged under climate change scenarios since extreme environmental processes disrupt and diminish global food production. For example, drought-induced increases in plant diseases and rainfall caused a decrease in food production. Machine Learning and Agricultural Big Data are high-performance computing technologies that allow analyzing a large amount of data to understand agricultural production. 
  • 443
  • 21 Dec 2022
Topic Review
Agricultural Water
Monitoring the microbial quality of water used in agriculture is important to reduce the likelihood of produce contamination and possible future foodborne outbreaks. The U.S. Food and Drug Administration has established the Produce Safety Rule as part of the Food Safety Modernization Act to improve the safety of produce that is normally consumed raw during growing, harvesting, packing and holding activities. In order to comply with the rule, growers need to follow some standards for the microbial quality of water that is used on the produce field, however, more information on the water microbial profile is necessary in order to improve the accuracy of the testing.
  • 839
  • 11 Jan 2022
Topic Review
Air Emissions by Canada's Pulp and Paper Mills
The pulp and paper industry is a major contributor to water and air pollution globally. Pulp and paper processing is an intensive energy consuming process that produces multiple contaminants that pollute water, air, and affect ecological and human health. In Canada, the National Pollutant Release Inventory (NPRI) is used to assess the release of air pollutants into the atmosphere from industrial facilities (including pulp and paper mills) and provides a repository of annual emissions reported by individual facilities. 
  • 558
  • 28 Apr 2022
Topic Review
Air Mercury Monitoring
The GMOS (Global Mercury Observation System) project has the overall goal to develop a coordinated observing system to monitor mercury on a global scale. We present the long-term (2011 – 2020) air mercury monitoring data obtained at the Listvyanka station located at a shore of Lake Baikal, Siberia. The long-term monitoring shows obvious seasonal variation of the background mercury concentration in air, which increases in the cold and decreases in the warm season. The short-term anomalies are associated with the wind carrying the air from the industrial areas where several big coal-fired power plants are located. A positive correlation between the mercury, SO2 and NO2 concentrations is observed both in the short-term variations and in the monthly average concentrations. The analysis of forward and backward trajectories obtained with the HYSPLIT model demonstrates revealing of the mercury emissions sources. During the cruise of 2018, the continuous air mercury survey over Lake Baikal covered 1800 km. The average mercury concentration over Baikal is notably less in comparison with the average value obtained at the onshore Listvyanka station during the same days of cruise. That can lead to the conclusion that Baikal is a significant sink of the atmospheric mercury.
  • 551
  • 15 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. 
  • 3.6K
  • 11 Jan 2022
Topic Review
Air Pollution Tolerance Index
Air pollution is a global environmental issue, and there is an urgent need for sustainable remediation techniques. Thus, phytoremediation has become a popular approach to air pollution remediation.
  • 841
  • 29 Mar 2022
Topic Review Peer Reviewed
Air Quality during Covid-19 Lockdown
Air pollution exposure is one of the greatest risks to health worldwide. It is estimated to be responsible for about 4.2 million deaths around the world every year owing to many serious diseases such as heart disease, stroke, acute and chronic respiratory diseases, and lung cancer. The WHO guideline limits are exceeded in several areas around the world, and it is estimated that about 90% of the world’s population is exposed to high air pollution levels, especially in low- and middle-income countries. The COVID-19 pandemic has forced governments to implement severe mobility restriction measures to limit the spread of the virus. This represented a unique opportunity to study the impact of mobility on urban air quality. Several studies which have investigated the relations between the quality of the air and such containment measures have shown the significant reduction of the main pollutants in the urban environment so to encourage the adoption of new approaches for the improvement of the quality of air in the cities. The aims of this entry are both a brief analysis and a discussion of the results presented in several papers to understand the relationships between COVID-19 containment measures and air quality in urban areas.
  • 1.2K
  • 13 Apr 2022
Topic Review
Air Quality in Mainland Southeast Asia
Air pollution, notably particulate matter pollution, has become a serious concern in Southeast Asia. The combustion of biomass has been recognized to considerably increase air pollution problems from particulate matter in this region. Consequently, its effect on people in this area is significant. 
  • 443
  • 28 Jun 2023
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