Gross alpha activity in urban sediments as an important indicator of urban environmental processes on the example of three Russian cities

Abstract

The protection of the urban environment from radioactive wastes (including technologically enhanced natural radionuclides) and potentially harmful elements have recently become very critical. Thus, the present study aimed to assess the radioactive levels in low-volume samples of dust and fine sand fractions of the urban surface deposited sediments (USDS) collected in three Russian cities. The detection was conducted via CR-39 and LR-115 type II solid-state nuclear track detectors (SSNTDs) have been used to detect gross alpha activity concentrations. A statistically significant difference was observed between the average gross alpha activity concentrations in the dust fraction and the fine sand fraction in each city. The obtained results also illustrate the gross alpha activity concentration in the dust fraction is higher than in the fine sand fraction. This is consistent with the results of the chemical and mineralogical analysis. The dust fraction size has a higher gross alpha activity concentration than the fine sand fraction due to the natural partitioning of the main minerals constituting USDS with trace uranium and thorium content (feldspar, plagioclase, amphibole and others) and negligible uranium and thorium content (quartz). In some cases, USDS radioactivity is associated with monazite and zircon. A good correlation (0.58) was found between the gross alpha activity concentration and the effective content of uranium and thorium. Finally, an assessment of the gross alpha activity concentrations in the USDS size fractions was considered an essential indicator of environmental processes that are significant in terms of their impact on human health.

Keywords: Gross alpha activity; Minerals; Monazite; Particulate matter (PM); Potentially harmful elements (PHEs); Radioactive.