| Abstrakt: |
The spatial distribution and temporal dynamics of industrial frequency electric and magnetic fields in St. Petersburg, Kazan, Belgorod and Petrozavodsk has been studied. It is established that electric fields of significant strengths occur near high voltage transmission lines (HVL) only. It is found that sanitary-protection and exclusion zones of the standard size do not always ensure a decrease in electric field strength to maximum allowable levels on their boundaries. Thus, the electric field strength of four HVL in St. Petersburg increases due to the mass construction of high-rise buildings leading to an increase in power consumption. A dependence of the electric field strength on meteorological factors was also determined, primarily on air humidity (direct dependence), and on atmospheric pressure (indirect inverse relationship). The industrial frequency magnetic field produces a variable city-wide background caused by a set of sources. The more intense is the technogenic load, the higher is magnetic induction, which renders it a convenient geoindicator for mapping. Also, the indicators of magnetic induction reflect the characteristics of power networks. Abnormally high values of magnetic induction were recorded in all cities, which are explained by the influence of electric cables. No exceedances of allowable levels of magnetic induction in residential areas were observed. [ABSTRACT FROM AUTHOR] |
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