Journal article
Changes in surface water quality after inundation of acid sulfate soils of different vegetation cover
Australian Journal of Soil Research, Vol.43(1), pp.1-12
2005
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Abstract
<p>Surface soils from an acid sulfate soil (ASS) backswamp were inundated in a temperature controlled environment and surface-water chemistry changes monitored. The soils had contrasting <em>in situ</em>vegetative cover [i.e. 2 grass species, <em>Cynodon dactylon</em> and <em>Pennisetum clandestinum</em> (Poaceae), and litter from <em>Melaleuca quinquenervia</em> (Myrtaceae)]. The different vegetation types had similar biomass and carbon content; however, there were large differences in the quality and lability of that carbon, which strongly influenced decay/redox processes and the chemical composition of surface waters. The grass species had more labile carbon. Their surface waters displayed rapid sustained O<sub>2</sub> depletion and sustained low Eh (~0 mV), high dissolved organic carbon (DOC), and moderate pH (5–6). Their soil acidity was partially neutralised, sulfides were re-formed, and reductive dissolution of Fe(III) led to the generation of stored acidity in the water column as Fe<sup>2+</sup><sub>(aq)</sub>. In contrast, <em>M. quinquenervia</em> litter was high in decay-resistant compounds. Its surface waters had lower DOC and low pH (<4) and only underwent a short period of low O<sub>2</sub>/Eh. Soluble Al caused <em>M. quinquenervia</em> surface waters to have higher titratable acidity and soil pH remained consistently low (~3.8–4.0). Concentrations of Cl<sup>–</sup> and Al in surface waters were strongly correlated to initial soil contents, whereas the behaviour of Fe and SO<sub>4</sub><sup>2–</sup> varied according to pH and redox status. This study demonstrates that changes in vegetation communities in ASS backswamps that substantially alter either (<em>a</em>) the pool of labile vegetative organic carbon or (<em>b</em>) the concentration of acidic solutes in surface soil can have profound implications for the chemical characteristics of backswamp surface waters.</p>
Details
- Title
- Changes in surface water quality after inundation of acid sulfate soils of different vegetation cover
- Creators
- Scott G Johnston - Southern Cross UniversityPeter G Slavich - New South Wales Department of Industry and Investment, Wollongbar Primary Industries InstitutePhillip Hirst - NSW Department of Primary Industries, Grafton Agricultural Research Station
- Publication Details
- Australian Journal of Soil Research, Vol.43(1), pp.1-12
- Identifiers
- 1585; 991012822156302368
- Academic Unit
- Faculty of Science and Engineering; Science; Southern Cross GeoScience; School of Environment, Science and Engineering
- Resource Type
- Journal article