Small-scale spatial variability of Technosol properties in a
chronosequence of reclamation of dredged sediment landfills
Abstract
Active reclamation is often necessary to ensure a transformation of
mining waste into Technosols -“soils dominated or strongly influenced
by human made material” - and restore its utility and environmental
value. The objective of this study was to assess the spatial variation
of the physicochemical properties of a Technosol forming on dredged
sediment landfills left by alluvial gold mining in a chronosequence of
reclamation (0, 4, 8 and 12 years). We hypothesized a higher spatial
dependency of most soil properties with increasing time of Technosol
formation and an overall homogenization of the soil resulting from
pedogenetic processes. Our results showed that most of the investigated
physical and chemical properties changed significantly among Technosols
of different ages. The content of organic matter, phosphorus, and
exchangeable cations showed the highest spatial variability in
Technosols of all ages. In older Technosols, most soil properties showed
less spatial variability than in younger Technosols. A multivariate
geostatistical assessment allowed the delineation of spatial clusters
i.e. homogeneous zones with distinctive physicochemical properties
within areas of the chronosequence. This spatial clustering showed that
reclamation and Technosol formation led to spatially-dependent
fragmentation processes reflected in more and smaller homogeneous zones
in the oldest Technosol assessed in the chronosequence. From the
perspective of reclamation management, understanding the spatial
variability of highly heterogeneous Technosols where substantial changes
can be observed within small distances can support the development of
reclamation strategies suitable to the characteristics of each field as
well as the determination of its potential uses.