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Land Contamination
Published in Daniel T. Rogers, Environmental Compliance Handbook, 2023
Radioactive decay occurs when an unstable atomic nucleus spontaneously loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type (parent nuclide) transforming into an atom of a different type (daughter nuclide). All elements with an atomic number greater than 80 possess radioactive isotopes, and all isotopes of elements with an atomic number greater than 83 are radioactive (Kathren 1991).
Chemistry of Contaminants
Published in Daniel T. Rogers, Environmental Compliance Handbook, 2023
Radioactive decay occurs when an unstable atomic nucleus spontaneously loses energy by emitting ionizing particles and radiation. This decay, or loss of energy, results in an atom of one type (parent nuclide) transforming into an atom of a different type (daughter nuclide). All elements with an atomic number greater than 80 possess radioactive isotopes, and all isotopes of elements with an atomic number greater than 83 are radioactive (Kathren 1991).
Planar Scintigraphy and Emission Tomography
Published in Bethe A. Scalettar, James R. Abney, Cyan Cowap, Introductory Biomedical Imaging, 2022
Bethe A. Scalettar, James R. Abney, Cyan Cowap
In many cases, radioactive decay is quantified in terms of activity, A, which is the number of decays per second. In light of Eq. (12.2), we have A=-dNdt=λN0e-λt=A0e-λt
Recent progress in radon-based monitoring as seismic and volcanic precursor: A critical review
Published in Critical Reviews in Environmental Science and Technology, 2020
Nury Morales-Simfors, Ramon A. Wyss, Jochen Bundschuh
Two types of analytical techniques have been developed for measuring radon activity in soil and water: (i) passive mode, in which radon enters to the device by natural diffusion and (ii) active mode, in which radon is pumped into a radon-detecting device. According to the measurement duration (time resolution), three types of sampling methods can be distinguished: (i) instantaneous or grab-sample technique (single-point samples collected over a short time frame), (ii) integrating technique (monthly or annual averages of radon concentrations) and (iii) continuous/active technique (accuracy time series concentrations) (Table 1). Radon measurement techniques are also classified based on three characteristics: (i) whether the technique measures radon or its daughter products, (ii) time resolution (i.e. accuracy and precision) and (iii) type of emission, either alpha, or beta particles or gamma radiation resulting from radioactive decay (Baskaran, 2016).
A mini-review on mechanochemical treatment of contaminated soil: From laboratory to large-scale
Published in Critical Reviews in Environmental Science and Technology, 2018
Giovanni Cagnetta, Jun Huang, Gang Yu
Metals can be divided in two classes: heavy metals and radioactive nuclides. “Heavy metals” is a generic term that indicates metallic and metalloid elements with relatively high atomic number and much higher density compared to water. Their physicochemical and biological properties are strongly influenced by the chemical species. Arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), lead (Pb), nickel (Ni), and zinc (Zn) are examples of heavy metals of major environmental concern (Sungur, Soylak, Yilmaz, Yilmaz, & Ozcan, 2015). Heavy metals produce a broad spectrum of negative effects on life (included genotoxicity and carcinogenicity), even at low doses, despite some of them are essential elements for biological activities (Kungolos, Samaras, Tsiridis, Petala, & Sakellaropoulos, 2006; Tchounwou, Yedjou, Patlolla, & Sutton, 2012). Radioactive nuclides refer to radioactive isotopes of heavy elements, such as cesium (Cs), radium (Ra), radon (Rn), and uranium (U). These elements are naturally found in the environment, but human activities (and also some natural events, like volcanic eruption) can increase their concentrations. Ionizing radiations of radioactive nuclides are well-known to be harmful to life (Meredith, 1960). They cause a large variety of DNA lesions that have major negative consequences on cellular activities of living beings, for example, cell death or carcinogenesis (Gregoire & Cleland, 2006; Little, 2000). Due to extremely long radioactive decay time (up to 100,000 years), radioactive nuclides are a serious threat to human health and the environment. Both heavy metals and radioactive nuclides have a certain mobility in the environment: water (i.e. meteoric precipitation and surface waters) can more or less (according to the chemical specie) transport these contaminants, which accumulate in soils and sediments and can enter the food web through plant up-take. Moreover, metal species are persistent, because they do not undergo natural attenuation processes, like microbial or physicochemical degradation. Hence, remediation of contaminated soil is fundamental to prevent bioaccumulation of such toxic species in crops and fodder, as well as transfer in drinking water (Bolan et al., 2014).