Characterization of products of the early stages of pedogenesis in ornithogenic soil from Maritime Antarctica

Abstract

Summary Limited pedogenesis on the Antarctic continent results in unusual, but important, short‐range order inorganic phases and organo‐mineral complexes (both with broad peaks from X‐ray diffraction) in the clay fraction, which can be studied by sequential chemical extractions. We aimed to develop a better sequential extraction procedure to obtain more detailed discrimination of the short‐range order phases (SROP) of the clay fraction of soil from Maritime Antarctica. Selected chemical properties of the soil and clay fraction were related to different phases of these products. The total amount of SROP and organo‐mineral complexes in the clay fraction ranged from 15.1 to 43.9%, with greater occurrence in ornithogenic soil. The continuous incorporation of guano from penguins into the soil profile has contributed to increasing amounts of organo‐mineral complexes. Short‐range order phases have an important effect on soil chemical properties, such as an increase in non‐exchangeable acidity, quantity of hydroxyl groups on the surface of the colloidal fraction, the buffering capacity of Al3+ from non‐exchangeable and structural forms of the element, and a decrease in soil CEC. The greater number of sequential extraction steps enabled the separation of SROP and organo‐mineral complexes into two phases of stability, with a clear predominance of the more soluble forms.

Adsorption of arsenate (HAsO42-) by the clay fraction of soils of the Keller and Barton Peninsulas, King George Island, Maritime Antarctic

“…Detalhes sobre os procedimentos analíticos das extrações sequencias podem ser obtidos em Poggere et al (2016).…”

Do Aggregate Size Classes of the Subsurface Soil Horizon Have Different Chemical/Mineralogical Properties?

“…Comparisons of the means are made only for the aggregates of the same soil. , since the Al-OH group is a weak acid whose pH value of the zero-charge point is between 8 and 9 (Poggere et al, 2016). However, these effects need to be confirmed in future studies, including the cultivation of plants in different classes of soil aggregates.…”

“…This aggregate class had the highest organic carbon content for the Ustrochrept (Table 1). Organic matter slows down the crystallization of Fe oxides and favors the stability of short-range order forms such as ferrihydrite (Kämpf and Schwertmann, 1983;Poggere et al, 2016). The short-range order Fe oxides present a high specific surface area and activity in the soil (Simas et al, 2006;Mendonça et al, 2013).…”

The Use of a Sequential Extraction Technique to Characterize Soil Trace Evidence Recovered from a Spade in a Murder Case in Brazil*

“…Some work in Brazil has concentrated on sequential chemical extraction of short-range order materials (SOR) and crystalline minerals from the clay fraction in forensic cases (16)(17)(18)(19)(20)(21)(22). The sequence of analyses adopted mixed methodologies for extraction of short-range order phase (SOR) and crystalline Fe oxides in nonforensic studies (23)(24)(25)) (with modifications): (i) 0.2 mol/ L pH 3.0 ammonium oxalate (AO); (ii) dithionite-citrate-bicarbonate (DCB); and (iii) 0.5 mol/L NaOH. The main modification used first for (16) in a simulated forensic case in relation to the method proposed by (24) was the inclusion of the extraction step with DCB.…”