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The freshwater environment
Published in Andrew Farmer, Managing environmental pollution, 2002
The sediment cores have to be dated in order to determine when changes may have occurred. This is most commonly done using radio-isotope changes to lead-210. This isotope has a half-life of 22.26 years, so levels of lead-210 allow accurate dating. Other components of the sediments can also be incorporated. For example, combustion of fossil fuels results in the production of small carbonaceous particles, and these remain in lake sediments. It is often noted that declines in lake pH do coincide with the appearance and increase in abundance of carbonaceous particles. Figure 4.3 shows an early example of pH reconstruction from the Round Loch of Glenhead in Scotland, showing changes in the abundance of different diatom species groups, lead-210 dates and pH.
Regulatory Framework
Published in Stephen M. Testa, Geological Aspects of Hazardous Waste Management, 2020
Mining in the U.S. on a grand scale commenced in the mid 1800s with such mining districts as Leadville in Colorado, the Tri-State Mining Area (Oklahoma, Kansas, and Missouri), and Anaconda in Montana, among others. In addition, the exploration and production of uranium and other strategic minerals since the 1940s have left a legacy of uranium mill tailing piles, asbestos and metal-contaminated soils, and numerous cases of groundwater contamination. Mining sites can vary in size from less than 1 acre to several square miles, thus producing large volumes of waste. Virtually all of the mining waste generated is disposed of on-site. Overburden and waste rock are typically placed in piles adjacent to the mine or used as backfill. Tailings are commonly disposed of as a slurry in unlined tailing impoundments, covering some 1500 ha within 24 sites in the western states. Primarily derived from extensive mining activities of the 1950s and 1960s, the material is composed of finely comminuted uranium ore in which all the uranium has been removed, but the radioactive daughter elements produced by radioactive decay remain. The most important of the radioactive daughter elements is radium (226Ra). If ingested, Ra can cause damage due to its intense alpha radiation. Ra also decays to produce radon (222Ra), a radioactive gas which can further decay into suspended solid radioactive products such as lead (210Pb) which, if inhaled, can lead to cancer. No longer covered by rock and soil to absorb the radiation and prevent appreciable migration, unconsolidated tailing piles provide an environment for the migration of decay products by dissolving in water and diffusing into air.
Radiation in the World Around Us
Published in Philip T. Underhill, Naturally Occurring Radioactive Material, 2018
Tobacco contains significant levels of lead-210 (210Pb) and polonium-210 (210Po), both alpha emitters. Approximately 50 million people in the United States smoke 20 to 30 cigarettes per day. These individuals receive an estimated annual dose to their lungs of approximately 8000 mrem (80 mSv). This exposure is from radionuclides taken up by the tobacco plant. Many plants are known to absorb lead from the soil and will therefore build up radioactive lead-210 in their tissues.
Ecological risk of heavy metals in sediment of an urban river in Bangladesh
Published in Human and Ecological Risk Assessment: An International Journal, 2018
Md. Saiful Islam, Ram Proshad, Saad Ahmed
Sampling was conducted in February–March 2013 (winter, dry season) and August–September 2013 (summer, wet season), respectively. At each sampling point, composite sediment samples were collected using standard protocol (USEPA 2001). The river bed sediment samples (about 200 g) were collected from 15 locations of the Buriganga River (Figure 1) at a depth of 0 to 5 cm using a portable Ekman grab sampler. For considering the background value of preindustrial sample, sediment was taken by means of a percussion hammer corer (50–80 cm in length) for metal analysis (Schottler and Engstrom, 2006). Sediment sampling was performed as prescribed in the methods manual for the characterization of sediments (Environment Canada and MENV, 1992). Lead-210 dating by alpha spectrometry method was used to determine the age and sediment accumulation rates. Each sediment sample was obtained by mixing sediments randomly collected (3 times) at each sampling point and 18 pairs of composite sediment samples were collected. Sediment samples were then freeze-dried to obtain constant weight. The samples were homogenized by grinding in an agate mortar, sieved through 106 μm aperture nylon sieve and stored in labeled glass bottles until chemical analyses.
Soil depth profile of 137Cs, 210Pb and 40K in Algeria
Published in Radiation Effects and Defects in Solids, 2019
M. Nadri, C.-E. Khairi, A. Ioannidou
Lead-210 is a long-lived radionuclide (T½ = 22.6 y) produced from the decay of 222Rn (T½ = 3.82 d), an inert noble gas, which is produced in the ground from the decay of 226Ra. (14–16). Since part of 222Rn produced in the ground exhales in the atmosphere, 210Pb is produced in the ground and in the lower atmosphere. 210Pb is a beta emitter with a half-life of 22.3 years and decays into 210Bi with a half-life of 5.01 days, which further decays into 210Po with a half-life of 138.4 days (17).
Analysis of the vertical distribution and size fractionation of natural and artificial radionuclides in soils in the vicinity of hot springs
Published in Radiation Effects and Defects in Solids, 2018
S. Padovani, I. Mitsios, M. Anagnostakis, D. Mostacci
Lead–210 shows a decreasing trend up to the depth of ∼18 cm, remaining constant henceforth. The specific activity varies from around 120 Bq/kg on the surface to ∼27 Bq/kg in the deep soil – almost four times lower. It should be mentioned that Lead–210 detected in the soil originates from Radon–222 decay, and therefore part of Lead–210 is produced in the atmosphere from the Radon–222 that has exhaled from the ground. This Lead–210 (referred to as unsupported Lead–210) is then deposited on the ground surface and migrates in the soil. Therefore, the vertical profile presented in Figure 6 is to be expected for Lead–210 and does not indicate any significant disturbance of the soil.The behavior of Radium-226 is more difficult to interpret. The activity concentration is approximately constant at ∼57 Bq/kg in the first 7 cm. In these sections Thorium–234 has an activity concentration of ∼55 Bq/kg, the two radionuclides are in equilibrium. From 7 to 10 cm, the activity concentration of Radium–226 sharply decreases from ∼57 Bq/kg to 17 Bq/kg, whilst from 10 to 20 cm it fluctuates around ∼16 Bq/kg, showing once again an approximately constant value. It is clear that in the deep soil there is significant disruption of equilibrium between Radium–226, Lead–210 and Thorium–234. All these trends cannot be easily explained. The higher values of Radium–226 activity concentration in the ground surface might be related to the addition of water carrying Radium–226. Soil disturbance could also be a reason for this anomalous behavior, yet, a complete explanation of Radium–226 vertical profile cannot be given.