The role of mineralogy, geochemistry and grain size in badland development in Pisticci (Basilicata, southern Italy)

Abstract

Mineralogical, geochemical and grain-size composition of soil and pore-water chemistry parameters were characterized on both eroded (south-facing) and non-eroded (north-facing) clayey-silt slopes in the Basilicata region (southern Italy).Only a few grain-size parameters and clay mineralogy discriminate eroded from noneroded substrates. Compared with the latter, the former have fractions of over 63 µ µ µ µ µm and 1-4 µ µ µ µ µm lower and fractions 4-63 µ µ µ µ µm higher. Grain-size characters of crusts did not discriminate with respect to substrate.Bulk rock mineralogy was not distinctive, but the clay mineral assemblage shows that the eroded slope is enriched in kaolinite, mixed layers (illite-smectite) and chlorite, whereas illite decreases, although overlaps are common.Chemical data enable discrimination between eroded and non-eroded slopes. pH, SAR (sodium adsorption ratio), TDS (total dissolved salts) and PS (percentage of sodium) are distinctive parameters for both eroded and non-eroded slopes. TDS increases in depth in the non-eroded slope, whereas the maximum TDS is just below the crust in the eroded one. On average, eroded substrates are higher in pH, SAR and PS than non-eroded ones. The ESP (exchangeable sodium percentage) of the eroded slope has a higher value than the non-eroded one. Crusts are less dispersive than eroded substrates, and non-eroded substrates behave as crusts. This suggests that the portion of the slope most severely exposed to weathering tends to stabilize, due to strong decreases in SAR, PS and ESP. Several diagrams reported in the literature show similarly anomalous crust samples on eroded slopes, compared with other samples coming from greater depths on eroded slopes. In the present case study, the exchangeable form of Na characterizes crusts more than the soluble form.This study describes the erosional mechanism, which involves morphological and geographic exposure and climatic elements, as well as grain size, mineralogy, chemistry and exchangeable processes of soils.

Erosion Related Changes to Physicochemical Properties of Ultisols Distributed on Calcareous

“…The correlation of gully erosion severity with soil intrinsic physico-chemical factors is asserted in the literature (Nordström, 1988;Lal, 2001, Battaglia, et al, 2002Summa et al, 2007, Rienks et al, 2000Piccarreta, 2006;Singh & Prakash, 2000). Further, the state of soil dispersion and erodibility in erosion prone areas has been related to the exchangeable sodium percentage (ESP), the sodium adsorption ratio (SAR), the sodium percentage (PS) and the total amount of dissolved salts (TDS) of the surface soils (Faulkner, 2006;Piccarreta et al, 2006;Torri et al, 1994), although gullying occurs in soils that do not exceed the erosion threshold for these parameters (Rienks, 2000).…”

Early Identification of Land Degradation Hotspots in Complex Bio-Geographic Regions

“…These mixed coniferous forests are sparse and fragmented by the presence of thin ridges and deep valleys (Figure 11a) caused by strong erosion [64,81]. Similar fragmentation processes are also detected within more natural vegetation covers.…”

Mapping badland areas using LANDSAT TM/ETM satellite imagery and morphological data

“…Another important aspect is the mineralogical and grain size composition of clays. Clay minerals, in fact, as the major component of these peculiar erosional landforms, play an important role in determining badland genesis (Battaglia et al, 2002;Summa et al, 2007). The origin of badlands still remains an open question due to the relationship of landform development to processes of different natures such as geological, geomorphological and denudation processes.…”