Abstract
Studies of gross alpha and gross beta activity in road- and surface-deposited sediments were conducted in three Russian cities in different geographical zones. To perform radiation measurements, new methods were applied which allow dealing with low mass and low volume dust-sized (2–100 μm) samples obtained after the size fractionation procedure. The 2–10 μm fraction size had the highest gross beta activity concentration (GB)—1.32 Bq/g in Nizhny Novgorod and Rostov-On-Don, while the 50–100 μm fraction size was most prominent in Ekaterinburg. This can be attributed to the presence of radionuclides that are transferred through natural and anthropogenic processes. The highest gross alpha activity concentration (GA) in fraction sizes was found in Rostov-on-Don city within the 50–100 μm range—0.22 Bq/g. The fraction sizes 50–100 μm have a higher gross alpha activity concentration than 2–10 μm and 10–50 μm fraction sizes due to natural partitioning of the main minerals constituting the urban surface-deposited sediment (USDS). Observed dependencies reflect the geochemical processes which take place during the formation and transport of urban surface sediments. Developed experimental methods of radiation measurements formed the methodological base of urban geochemical studies.
Highlights
There has been a variety of natural radionuclides in the aquatic and terrestrial ecosystems since Earth’s creation
The objective of the present work is to study the concentration of gross alpha and gross beta activity in size-fractionated samples obtained from the urban surface-deposited sediment (USDS) in three Russian cities: Ekaterinburg, Rostov-On-Don, and Nizhny Novgorod
The chemical analysis illustrated that USDS contains uranium and thorium, which was higher in the fraction 50–100 μm than in the fractions 2–10 and 10–50 μm in the cities under study
Summary
There has been a variety of natural radionuclides in the aquatic and terrestrial ecosystems since Earth’s creation. Many studies have measured radionuclide concentrations in various environmental matrices, such as the crust, rocks, sandy beaches, building materials, and the atmosphere [2,3,4]. Natural radionuclides in minerals and raw materials of natural origin are constantly emitted ionizing radiation that can be exposed to human beings and biota [3,5]. Occurring radioactive materials (NORMs) have resulted from human activities that increase human exposure to Earth’s crust radionuclides and can be found in water, air, food, building materials, and the human body [4,6,7,8]. Radiation hazards are from external and internal exposure to these radioactive isotopes. External exposure is associated with direct gamma radiation emitted from the isotopes in the U and Th series, as well as from 40K. It is suitable to identify the sources of radionuclides, the transportation into the environment, and their migration [13]
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