Charge fingerprint in relation to mineralogical composition of Quaternary volcanic ash along a climatic gradient on Java Island, Indonesia

Journal Article · Wed Jan 02 00:00:00 EST 2019 · CATENA

DOI:https://doi.org/10.1016/j.catena.2018.09.024· OSTI ID:1510977

Utami, S. R. ^[1]; Mees, Florias ^[2]; Dumon, Mathijs ^[3]; Qafoku, Nikolla  ^[4]; Van Ranst, Eric ^[5]

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1. <-- Click to select University
2. Royal Museum for Central Africa, Tervuren, Belgium
3. Ghent University
4. BATTELLE (PACIFIC NW LAB)
5. Laboratory of Soil Science, University of Gent, Belgium

We studied the relationship between the mineralogical composition and surface charge properties of representative Quaternary volcanic ash soils, classified as Andosols, along an East-West sequence on Java Island in Indonesia. Most of the studied soils have a limited ability to retain cations under their forest or grass vegetation. The surface charge properties of these soils are mainly controlled by the relative amounts of nanocrystalline minerals, mainly allophane and to a lesser extent ferrihydrite, in addition to organic matter (especially Al- and Fe-humus complexes), crystalline Fe oxides, gibbsite, and layer silicates (e.g., halloysite, smectite, kaolinite). Based on the composition of their clay fraction, the studied soils can be grouped in two categories: (i) allophane-poor Andosols of East Java, which contain a considerable amount of either halloysite or a mixture of 2:1 and 1:1 layer silicates; and (ii) allophane-rich Andosols dominated either by kaolinitic clays, gibbsitic material or a mixture of 1:1 and 2:1 layer silicate clays, which are more prominent in West and also occur in Central Java. Differences between both groups are attributed mainly to more pronounced seasonality in East Java, with variations in parent ash composition, becoming more acidic from east to west, as subordinate factor. The more severely leaching environment in West Java results in a higher degree of desilication , which led to a higher point of zero net charge (PZNC) and pHo in the allophane-rich soils. The soils belonging to this group exhibit extreme variable charge characteristics, and a net ‘positive’ variable surface charge at soil pH.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1510977
• Report Number(s): PNNL-SA-135121
• Journal Information: CATENA, Vol. 172
• Country of Publication: United States
• Language: English