Secondary enrichment of soil by alkaline emissions: the specific form of
anthropogenic soil degradation near magnesite processing factories and
possibilities of land management
Abstract
Over the past 90 years, anthropogenic degradation of soil caused by
alkaline, magnesium-rich dust deposit has presented a serious problem
near magnesite processing factories in Jelšava and in Lubeník
(Slovakia). The objective of this study was to investigate the chemical
and biological soil properties in 14 sampling sites at different
distances from factories, and based on the results, to propose further
use of affected land. Results revealed that the available Mg 3–68 fold
exceeded very high content for texturally medium soils at all grassland
sampling sites, and areas close factory contained up to 14.4–17.4 g
kg-1. Higher excess of available Mg caused significant increase of soil
pH (up to 9.39) and worsened the conditions for the growth of
vegetation. As a result, lower stock of newly formed organic matter
(0.50–0.96 g kg-1 of labile carbon) with consequently weaker enzymatic
activity occurred. Therefore, enrichment by organic matter provides a
measure to support the biological activity of soil. The content of
monitored heavy metals (Zn, Cu, Pb and Ni) was not related to Mg and did
not influence the enzymatic activity of soil. Because alkaline emissions
have decreased by 99.8% since 1970, the application of classical
measures (mechanical removal of the Mg-rich crust, incorporation of
gypsum and manure to the soil), or newer methods (growing of Mg
hyper-accumulating plants) can offer more lasting positive effects than
those of 50 years ago. This study concluded that Mg-rich, alkaline dust
deposition causes long-lasting anthropogenic soil degradation.