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Topic Review
Rainfall Threshold
Sediment-related disaster is one of the most significant natural disasters, from the perspective of magnitude, damage and loss to human life and infrastructure, and disruption to socio-economic activities. The rainfall threshold is the condition or amount of rainfall that is likely to initiate sediment-related disasters, it is agreed that the rainfall threshold is the most significant tool to predict impending occurrences.
  • 1.4K
  • 26 Oct 2022
Topic Review
Rainfall Measurement by Commercial Microwave Links
As one of the most critical elements in the hydrological cycle, real-time and accurate rainfall measurement is of great significance to flood and drought disaster risk assessment and early warning. Using commercial microwave links (CMLs) to conduct rainfall measure is a promising solution due to the advantages of high spatial resolution, low implementation cost, near-surface measurement, and so on.
  • 770
  • 29 Jun 2022
Topic Review
Rainfall Data
As is widely recognized, rainfall data is necessary for the mathematical modelling of extreme hydrological events, such as droughts or floods, as well as for evaluating surface and subsurface water resources and their quality. The phase, quantity, and elevation of generic hydrometeors in the atmosphere can be estimated by ground-based radars. Satellites can provide images with visible and infrared radiation, and they can also serve as platforms for radiometers to derive the quantity and phase of hydrometeors. Radars and satellites provide spatial information on precipitation at wide scales, avoiding many problems connected to local ground measurements, including those for the areal inhomogeneity of a network. However, direct rainfall observations at point scale can be obtained only by rain gauges installed at the soil surface.
  • 8.3K
  • 29 Jan 2022
Topic Review
Radon Risk Perception, Awareness and Knowledge
Radon is a natural radioactive gas that is present in buildings and is the second cause of lung cancer after smoking. Risk perception has been studied from multiple perspectives, including social studies, anthropology, and medical disciplines, with psychology playing a primary role. Two main dimensions are involved in risk perception: a cognitive dimension, related to knowledge and understanding of risk, and an emotional dimension, which includes feelings; both are components of the reaction to risks, representations of immediate and/or future consequences and their implications, and how people decide how to behave accordingly. Perceived risk is therefore quantifiable and predictable: the psychometric paradigm has helped to clarify how certain elements and characteristics are specifically influential in people’s perception of the dangerousness of an activity, such as controllability, voluntariness, threat to future generations, and responsibility. The research for the implementation of evidence-based radon communication programs is progressing rapidly. Many countries have issued regulations or recommendations to ensure that radon concentration levels do not exceed certain threshold values. Following the results of numerous epidemiological studies conducted two decades earlier, in 2009 the World Health Organization proposed a reference level of 100 Bq m−3 to minimize health risks from indoor radon, adding that if this level could not be achieved due to country-specific conditions, the chosen reference level should not exceed 300 Bq m−3. According to the 2013 Euratom Directive, radon is an indoor pollutant monitored in workplaces and homes, with established limits and exposure control obligations but exposure continues to be very high in some situations.
  • 385
  • 31 Aug 2022
Topic Review
Radon Flux Characteristics
Radon is a noble radioactive gas, and almost half of the effective doses from all ionising radiation comes from exposure to radon and its short-lived decay products. Radon flux measurements provide information about how much radon rises from the ground toward the atmosphere, thus, they could serve as good predictors of indoor radon concentrations. Although there are many different mapping methods with many different input data, radon flux data are generally missing and are not included for the delineation of radon priority areas (RPA).
  • 571
  • 19 Jan 2023
Topic Review
Radionuclides in Mosses
The science of the mosses, bryology, knows three main categories of mosses according to constitution and habit. Hornworts (anthocerotophyta), liverworts and bryophytes. The latter are most common. Mosses are non-vascular plants. They adsorb water and nutrients mainly through their leaves. They have a rhizoid only for fixation on the substrate. A water conducting function of the rhizoid is not known. Mosses are suitable as bio-indicator plants. They can take up contaminants and radionuclides directly from the air. Compared to other plants they dispose of a higher surface area. Therefore, there is an ability for accumulation effects. Further, mosses dispose of an active metabolism also in winter. The monitoring of mosses and lichens is well described in literature. Focus in the papers about mosses is on heavy metals, nutrients and air contaminants. Only few papers deal with radio contaminants. 
  • 399
  • 09 Jul 2021
Topic Review
Radioactivity in Plastic Materials
All fossil combustible materials, such as coal and crude oil, contain radioactive elements, which origin from the natural decay series of uranium and thorium. The basic material for the synthesis of plastics is crude oil. Therefore, plastics may contain radionuclides. The gamma ray analysis of different rubbish bags used in the city of Basel show a clear contamination with uranium, radium (226Ra and 228Ra) and lead (210Pb), resulting in a yearly charge of 300, 300, 150 and 3,000 MBq each. In comparison with the contamination level of the burning ashes, these charges are not relevant (less than 1% of the content in the slags from the waste incineration). Nonetheless, we note a permanent displacement of long-lived natural radionuclides to landfill-sites.
  • 1.6K
  • 05 Jul 2021
Topic Review
Radioactive Wastewater Treatment Technologies
How to treat radioactive wastewater deeply and efficiently has become the most critical issue in the development of nuclear energy technology. The radioactive wastewater produced after using nuclear technology has the characteristics of many kinds, high concentration, and large quantity. Therefore, it is of great significance to study the treatment technology of radioactive wastewater in reprocessing plants.
  • 993
  • 23 Feb 2023
Topic Review
Radio Atmospheric
A radio atmospheric signal or sferic (sometimes also spelled "spheric") is a broadband electromagnetic impulse that occurs as a result of natural atmospheric lightning discharges. Sferics may propagate from their lightning source without major attenuation in the Earth–ionosphere waveguide, and can be received thousands of kilometres from their source. On a time-domain plot, a sferic may appear as a single high-amplitude spike in the time-domain data. On a spectrogram, a sferic appears as a vertical stripe (reflecting its broadband and impulsive nature) that may extend from a few kHz to several tens of kHz, depending on atmospheric conditions. Sferics received from about 2,000 kilometres' distance or greater have their frequencies slightly offset in time, producing tweeks. When the electromagnetic energy from a sferic escapes the Earth-ionosphere waveguide and enters the magnetosphere, it becomes dispersed by the near-Earth plasma, forming a whistler signal. Because the source of the whistler is an impulse (i.e., the sferic), a whistler may be interpreted as the impulse response of the magnetosphere (for the conditions at that particular instant).
  • 330
  • 25 Nov 2022
Topic Review
Radar-based Rainfall Information
Radar-based rainfall information has been widely used in hydrological and meteorological applications, as it provides data with a high spatial and temporal resolution that improve rainfall representation. However, the broad diversity of studies makes it difficult to gather a condensed overview of the usefulness and limitations of radar technology and its application in particular situations. 
  • 1.4K
  • 22 Feb 2021
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