Pedosphere 10(3): 237--245, 2000
ISSN 1002-0160/CN 32-1315/P
©2000 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Iron monosulfide distribution in three coastal floodplain acid sulfate soils, eastern australia |
| R. T. BUSH, L. A. SULLIVAN and C. LIN |
| School of Resource Science and Management, Southern Cross University, Lismore, NSW 2480 (Australia) |
| ABSTRACT |
| The distribution of iron monosulfide (quantified as acid volatile sulfur: SAV) was compared with geochemical properties that are known to affect its formation and accumulation in three coastal Holocene acid sulfate soils (ASS) at Tuckean Swamp, McLeods Creek and Bungawalbyn Swamp respectively. These properties included pH, reactive iron (FeR), pore-water sulfate (SO42-) and organic carbon (OC). Iron monosulfide was concentrated at the oxic/anoxic boundary. The Tuckean Swamp and McLeods Creek sites are Holocene sediments, whereas the Bungawalbyn Swamp is a Holocene peat. The concentration of SAV averaged 0.2 g kg-1 in a 0.5 m thick soil layer at the Tuckean Swamp, but was an order of magnitude lower in the oxic/anoxic transition layers at McLeods Creek and Bungawalbyn Swamp. The SAV mineral greigite (Fe3S4) was identified in the Tuckean Swamp by X-ray diffraction and scanning electron microscopy with quantitative energy dispersive X-ray analysis (SEM-EDX). Very small concentrations of greigite were also observed in the McLeods Creek, based on crystal morphology and elemental composition. The concentration of SAV was a small fraction of the total reduced sulfur, representing at most 3% of the pyrite sulfur. However, the presence of this highly reactive sulfide mineral, distributed within pores where oxygen diffusion is most rapid, has important implications to the potential rate of acid production from these sediments. |
| Key Words: acid sulfate soils, monosulfide, pyrite, oxidation, sulfid |
| Citation: Bush, R. T., Sullivan, L. A. and Lin, C. 2000. Iron monosulfide distribution in three coastal floodplain acid sulfate soils, eastern australia. Pedosphere. 10(3): 237-245. |
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