Toxicity of mercury and its compounds is well known, and they are considered as substances of heightened concern. Though mercury is to some extent released into the environment by natural processes such as volcanic eruptions, additional releases from anthropogenic sources have increased the environmental exposure and deposition significantly. There are many commonly used items containing mercury, for instance, mercury light bulbs, switches, and mercury thermometers, the disposal of which into trashcans can cause an increase of mercury concentration in the air of the local area. The paper reports mercury pollution surveys performed in several districts of Riga (the capital of Latvia). Using an RA 915+ Zeeman atomic absorption spectrometer, the concentration of mercury was measured in the air above objects of interest. The measurements mainly made from driving a car equipped with a GPS receiver have allowed the assignment of Hg concentration to a particular place to provide a digitised pollution database in geographic coordinates at different times. Results of the surveys show the background concentration of atmospheric mercury in Riga generally did not exceed 5 ng/m 3 while some places of increased mercury pollution need particular attention and clean-up. Examples of such surveys are shown.
In this work, the diagnostics using tomography in Hg/Xe and Hg/Ar capillary lamps is presented. First, the imaging of the lamps was performed using selected emission lines of mercury, argon and xenon in different operation conditions. Thus the tomographic reconstruction was made, to determine the spatial distribution of the emitting Hg and rare gas atoms. Significant differences of the distribution of the emitting atoms have been found in vertical and horizontal operation positions. The emitting mercury atoms in the state 73S1 were differently distributed within the lamp in the vertical and horizontal lamp positions. The radial profile has demonstrated a substantial depletion of the population density from the lamp centre in the vertical operating position, whereas the profile had a flat top shape in the horizontally operating lamp. A theoretical hypothesis is proposed to explain the observed phenomenon. Strong inhomogeneous structure of the argon atom distribution was found as well.
Mercury Pollution Exploration in Latvia with High-Sensitivity Zeeman Atomic Absorption Spectrometry
This research presents Hg pollution measurements performed in Latvia with sensitive method using Zeeman AAS analyzer RA-915+ and necessary attachments. Air in Riga city and water samples from a number of rivers and lakes of Latvia were analyzed for presence of low-level Hg concentrations. Ombrotrophic bog peat was analyzed to get insight into long-term trends. Environment in the sites sampled is relatively clean according to the results obtained, but there are local spots of pollution.
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