Chemical conditions in acidic water in the Plain of Reeds, Viet Nam

Tin, Nguyen Thanh; Wilander, Anders

doi:10.1016/0043-1354(94)00287-h

Cited by 20 publications

(5 citation statements)

References 13 publications

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“…In the dry season, water table depletion results in strong acid soil reactions as a result of oxidation of reduced sulfur compounds (Hanhart et al 1997;Tipping et al 2003). The subsequent recovery of the water table with high rainfall in an early wet season can flush out a lot of acids and soluble metals into adjacent aquifers (Minh et al 2002;Tin and Wilander 1995). Inundation by flooding in the mid rainy season improves the strong acid conditions, probably because of the consumption of protons during the iron-reducing process that is frequently accompanied by the decomposition of labile organic matter (Johnston et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Effects of drying on the release of solutes from acid sulfate soils distributed in the Mekong Delta, Vietnam

Kawahigashi¹,

Minh²,

Nguyen³

et al. 2008

Soil Science and Plant Nutrition

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Acids and soluble metal loads resulting from strong acidification preceded by severe drying of acid sulfate soils are fatal soil conditions for agricultural productivity and aquaculture environments. A greater concentration of dissolved Al and Fe after seasonal drought was confirmed in our previous paper using acid sulfate soils in the Mekong Delta. Furthermore, moisture desiccation resulting from land-use change and subsoil excavation for drainage probably promotes soil oxidation followed by acidification. We prepared air-dried soil moisture condition actual acid sulfate soils in the Mekong Delta to evaluate acidification and the release of acids and metals with drying. The pH values of the deepest horizon in the Hydroaquentic Sulfaquepts drastically dropped and greater concentrations of Al and Fe were released with drying. It was a common change from the sulfidic horizon to the sulfuric horizon. A large increase in Al release without a drop in pH after drying was observed in the sulfuric horizons of the Typic Sulfaquept, which developed on the oldest land in the Mekong Delta. Acidification by oxidation of reduced sulfur compounds might be compensated mainly by exchangeable Al and/or by the dissolution of Fe and Al oxides. In contrast, the concentration of Al increased slightly by drying in the sulfuric horizons in the Hydroaquentic Sulfaquept, which developed in the newer delta. The exchangeable basic cations in these soil horizons might still be effective in compensating for the protons produced by the oxidation of pyrite. The difference in the Al released by drying between the two sulfuric horizons might be attributed to the ripeness of the acid sulfate soils. The ripeness of the soil on the older delta might be higher than that on the younger delta. In this study, drying of acid sulfate soils, even in the sulfuric horizon, can promote metal release due to the exchange by protons derived from the oxidation of reduced sulfur compounds. However, further acidification might be compensated by a substantial amount of exchangeable cation and oxide dissolution.

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Section: Introductionmentioning

confidence: 99%

Effects of drying on the release of solutes from acid sulfate soils distributed in the Mekong Delta, Vietnam

Kawahigashi¹,

Minh²,

Nguyen³

et al. 2008

Soil Science and Plant Nutrition

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“…These saturated soils have low bulk densities and volumetric water contents around 80%. They are frequently gel‐like and pose considerable engineering and environmental problems because they shrink significantly on drying, deform and flow under surface loads, and export highly acidic groundwaters following drainage and subsequent sulfide oxidation [ Willett et al , 1993; Tin and Wilander , 1995; Wilson et al , 1999]. Oxidation of sulfides and ensuing soil acidification produce high concentrations of dissolved multivalent aluminum and iron in pore waters that react with the soil's exchange complex.…”

Section: Introductionmentioning

confidence: 99%

Dewatering and the hydraulic properties of soft, sulfidic, coastal clay soils

White

Smiles

Santomartino

et al. 2003

Water Resources Research

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[1] Dewatering and consolidation of saturated swelling soils are governed by pressuredependent soil hydraulic properties. Existing measurement techniques are difficult and slow. We illustrate a simple, rapid desorption technique, developed for industrial slurries, to measure hydraulic properties of a gel-like sulfidic, estuarine soil ($70% water content). Measured hydraulic conductivities, K(ψ), were very small, $10 À10 m/s, giving a representative capillary fringe thickness of $7 m and characteristic gravity drainage times around 40 years. Capillarity therefore dominates flow in these soils. Estimated times for dewatering this soil under surface loading with closely spaced, vertical wick drains, are 2 to 70 years, consistent with experience. A Netherlands marine clay soil, saturated with seawater, is unexpectedly wetter than the brackish estuarine soil here at the same matric potential, ψ. However, K(ψ) for both soils overlap, suggesting the engineering approximation, K(ψ) / jψj À1 , for marine-deposited clays. The functional dependencies of hydraulic properties surprisingly are not consistent with similar-media or double-layer theories.

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“…It is easy to see that leachate solutions were undersaturated with respect to alunite, basaluminite, and diaspore, but might have been in equilibrium with a jurbanite‐like solid phase. We do not know whether our leachates were in a true equilibrium with the minespoil material, but many other studies have shown the possibility of jurbanite controlling Al 3+ activity in acidic and acid sulfate soils (Evans, 1991; Menzies et al, 1994; Tin and Wilander, 1995; Vogt et al, 2001). Karathanasis et al (1988), who found very conclusive solution data evidence for the presence of a jurbanite solid phase, were unable to find jurbanite peaks in X‐ray diffraction experiments in the corresponding soil material.…”

Section: Resultsmentioning

confidence: 88%

Compost and Calcium Surface Treatment Effects on Subsoil Chemistry in Acidic Minespoil Columns

Willert

Stehouwer

2003

J of Env Quality

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Surface incorporation of a liming agent in combination with compost or biosolids is a proven way to revegetate acidic minespoils, but little is known about the effect of the surface amendments on subsoil chemistry. We conducted a greenhouse column experiment to investigate how different surface amendments affected plant growth and subsoil chemistry in highly acidic minespoil material. Columns were filled with shale minespoil material (pH approximately 2.5), amended with CaCO3, CaSO4 x 2H2O (gypsum), and two rates of compost, and seeded with birdsfoot trefoil (Lotus corniculatus L.) and 'Kentucky 31' tall fescue (Festuca arundinacea Schreb.). We measured leachate and plant growth over a 170-d period with extensive irrigation. Without CaCO3, plants could only grow at the high compost rate (68.8 g kg(-1)), even though the soil pH in those treatments was below 3.5, indicating the capability of natural organic matter to detoxify Al(3+) by forming Al-organic matter complexes. Compost had no effect on the subsoil. When CaCO3 or gypsum was added to the surface, extractable Ca increased in the subsoil, but there was no relevant increase in subsoil pH. Even in the first 5 cm of subsoil material, extractable Al did not decrease very much, possibly because a jurbanite-like solid phase controlled subsoil Al(3+) activities. During the reclamation of highly acidic minespoil material one should therefore not expect significant effects of the surface treatment on the untreated subsoil. A sufficient root zone would have to be achieved by incorporating the liming agent down to the desired rooting depth.

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Chemical conditions in acidic water in the Plain of Reeds, Viet Nam

Cited by 20 publications

References 13 publications

Effects of drying on the release of solutes from acid sulfate soils distributed in the Mekong Delta, Vietnam

Effects of drying on the release of solutes from acid sulfate soils distributed in the Mekong Delta, Vietnam

Dewatering and the hydraulic properties of soft, sulfidic, coastal clay soils

Compost and Calcium Surface Treatment Effects on Subsoil Chemistry in Acidic Minespoil Columns

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