Bracken (Pteridium aquilinum (L.) Kuhn) is a common fern found on all continents except Antarctica. It is under suspicion of causing cancer among people who utilizes it as food. The main carcinogenic compound is thought to be the water-soluble compound ptaquiloside. Ptaquiloside-uptake may occur not only through food, but also via drinking water as ptaquiloside might leach from plant material. The purpose of the study was to identify environmental parameters that correlate with the ptaquiloside-content in fronds, and to quantify the amount of ptaquiloside in the soil environment. The ptaquiloside-content in fronds, Oi/Oe-, and Oa/A-horizons was quantified at end of the growth season at 20 sites in Denmark. The fronds had ptaquiloside-contents between 108 and 3795 microgg(-1). The Oi/Oe-horizons had contents between 0.09 and 7.70 microgg(-1), while Oa/A-horizons had contents between 0.01 and 0.09 microgg(-1). The ptaquiloside-content in the standing biomass, which could be transferred to the soil by the end of the growing season, ranged between 10 and 260 mgm(-2), with nine sites having ptaquiloside loads over 100 mgm(-2). The carbon-content in the O-horizon, the precipitation, the amount of Bracken-litter, the turnover rate and the size of Bracken-stands determined the ptaquiloside-content in the soil materials while the content in fronds was found to be a function of the frond-height and the light-exposure in the ecosystem.
Serum selenium concentration of 220 residents in 11 Astrakhan districts was investigated, the concentration range being 87-133 microg/l. The lowest values were typical for Krasnoyarsk district possessing sandy soils with low content of humus. The highest human selenium status was demonstrated for Volga delta with alluvial saturated salty soils. Correlation coefficient between serum selenium and soils selenium was +0.6226.
The stock and structure of organic substances in the pine tree plantations on the overburden dumps of open-cut coal mines in Middle Siberia have been determined. It has been shown that the forming forest biogeocenoses differ from the natural phytocenoses and soils of the forest landscapes in the structure of the carbon pool and its distribution between the vegetation and soil components. In artificial forest ecosystems, the bulk of the plant component is accumulated in the aboveground part of the forest stand (40-59%). The aboveground grass cover contains only 0.1-1.4% of the total phytomass stock of the ecosystem. The annual accumulation of organic substances in the initial soils amounts to 0.28-1.45 t/ha.
The prevalence of multiple sclerosis (MS) and some physical and chemical properties of soil in two counties of Finland have been compared. In the county where the MS prevalence rate was significantly higher, the pH of the soil was lower, the organic carbon content higher, the concentration of soluble iron, zinc, chromium and aluminium higher and those of soluble potassium, calcium, magnesium, strontium and total selenium lower than in the county with the lower MS-prevalence rate. According to the literature, areas of a high MS prevalence correspond rather closely to the global distribution of mires, particularly to raised bogs in the northern hemisphere.
Selenium has many health effects, both beneficial and harmful. Chemical climatology has been a valuable background for explanation of the geomedical effects of this element. Geomedicine is the science dealing with the influence of ordinary environmental factors on the geographical distribution of health problems in humans and animals.