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Occurrence and abundance of monosulfidic black ooze in coastal acid sulfate soil landscapes

Richard T. Bush A B , Diane Fyfe A and Leigh A. Sullivan A

A Centre for Acid Sulfate Soil Research, Southern Cross University, Lismore, NSW 2480, Australia.

B Corresponding author; email:

Australian Journal of Soil Research 42(6) 609-616
Submitted: 16 May 2003  Accepted: 20 April 2004   Published: 17 September 2004


Organic oozes enriched in iron monosulfides are called monosulfidic black ooze (MBO). The occurrence and abundance of MBO were quantified in natural tributaries and man-made drainage canals on a typical coastal river floodplain. Thick deposits of MBO occurred in drains and the protected upper reaches of tributaries in acid sulfate soil (ASS) areas. Acid-tolerant lilies grew prolifically in these areas, contributing large amounts of decaying organic debris. The MBO contained up to 6.3% acid-volatile sulfur (equivalent to 18% iron monosulfide), an order of magnitude greater than reported previously for natural sediments. It also contained up to 6% pyritic sulfur (equivalent to approximately 11% pyrite). Sulfate and iron from surrounding ASS combined with abundant organic matter and protected flow in ASS drains provide excellent conditions for sulfate reduction, leading to iron sulfide precipitation and the accumulation of organic detritus. When mixed with water, the iron monosulfide in MBO can react within minutes to completely consume dissolved oxygen. There are thousands of drains in ASS areas that may have thick deposits of MBO. The MBO has the potential to cause rapid and severe effects on water quality. The challenge is to develop management practices that reduce the formation and accumulation of MBO in acid sulfate landscapes.

Additional keywords: pyrite, iron sulfides, de-oxygenation, water quality.


Berner RA1970Sedimentary pyrite formation.American Journal of Science268123

Bush RTSullivan LA1997Morphology and behaviour of greigite from a Holocene sediment in eastern Australia.Australian Journal of Soil Research35853861

Bush RTSullivan LAFyfe DJohnston SJ2004Redistribution of monosulfidic black oozes by floodwaters in a coastal acid sulfate soil floodplain.Australian Journal of Soil Research42603607

Dent D 1986 ‘Acid sulphate soils: a baseline for research and development.’ ILRI Publication 39. International Institute for Land Reclamation and Improvement Wageningen, The Netherlands

Gagnon CMucci APelletier E1995Anomalous accumulation of acid-volatile sulphides (AVS) in a coastal marine sediment, Saguenay Fjord, Canada.Geochimica et Cosmochimica Acta5926632675

Goldhaber MB Kaplan IR 1974 The sulfur cycle. ‘The sea. Vol. 5. Marine chemistry’. Goldberg ED 569 655 Wiley-Interscience New York

Howarth RWMerkel S1984Pyrite formation and the measurement of sulfate reduction in salt marsh sediments.Limnology and Oceanography29598608

Hsieh YPShieh YN1997Analysis of reduced inorganic sulfur by diffusion methods: improved apparatus and evaluation for sulfur isotopic studies.Chemical Geology137255261

Morse JWCornwell JC1987Analysis and distribution of iron sulfide minerals in recent anoxic marine sediments.Marine Chemistry225569DOI

Rickard D Schoonen MAA Luther GW 1994 Chemistry of iron sulfides in sedimentary environments. ‘Geochemical transformations of sedimentary sulfur’. Vairavamurthy MA Schoonen MAA 168 193 American Chemical Society Washington, DC

Sammut JMelville MDCallinan RBFraser G1995Estuarine acidification: the impacts on aquatic biota of draining acid sulfate soils in coastal floodplains.Australian Geographical Studies3389100

Sammut JWhite IMelville MD1996Acidification of an estuarine tributary in eastern Australia due to drainage of acid sulfate soils.Marine and Freshwater Research47669684

Sullivan LA Bush RT 2000 The behaviour of drain sludge in acid sulfate soil areas: some implications for acidification of waterways and drain maintenance. ‘Proceedings of Workshop on Remediation and Assessment of Broadacre Acid Sulfate Soils’. Slavich P 43 48 Lismore, NSW Acid Sulfate Soils Management Advisory Committee Wollongbar, NSW

Tulau MJ 1999 ‘Acid sulphate soil management priority areas on the Lower Richmond River floodplain.’ NSW Department of Land and Water Conservation Sydney, NSW

Wang QMorse JW1996Pyrite formation under conditions approximating those in anoxic sediments. (I) Pathways and morphology.Marine Chemistry5299121

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