The main differences between urban and natural soils result from the accumulation
of anthropogenic materials, which form a cultural layer with specific
properties and composition. Szeged is an ideal sampling area for researching
urban soils due to intensive artificial infill following the 1879 Great Flood as
well as other anthropogenic activities owing to the expansion of urban functions
that define the morphology of soils here. We took samples at 25 sites in 2005
and 2006 from horizons of soil profiles located in city areas and peripheral
profiles of the original genetic soil type for physical and chemical analysis.
Average topsoil samples (0-10 cm depth, 2-4 m2) were taken near the profiles in
order to determine the concentrations of heavy metals (Co, Cu, Ni, Pb, Zn, Cr,
Cd) in these soils so as to classify them according to the toxic properties
described in the World Reference Base for Soil Resources and to identify the
origins of these elements (anthropogenic vs. geogenic). Topsoil samples were
also collected in October 2006 at 10 sites representing three zones (city,
suburban, peripheral zone) to survey some basic biological properties of mesofaunal
elements and their community structure.
We claim that all the soil parameters except total salt content are excellent
markers of human influence. This is well supported by a discriminant analysis of
the above-mentioned parameters. In our analysis of heavy metals, we distinguished
elements of anthropogenic (Cu, Ni, Pb, Zn) and natural or lithogenic
(Co, Cr, Cd) origin. Following a quantitative evaluation of elements, according
to the proposal of the World Reference Base for Soil Resources, profiles where
the concentration of any metal element exceeded the limit values in the topsoil
were marked with the suffix Toxic. According to a mezofauna (oribatid mites,
collembolans) investigation, it seems that the intermediate suburban zone has a
more heterogeneous and stable mezofaunal community structure than the other
two zones. The lowest abundance values were found in the city zone. Based on
our evaluation of diagnostic properties and the results of our discriminant
analysis, four main soil types can be identified in Szeged related to the degree of
human influence
