Mobilisation, alteration, and redistribution of monosulfidic sediments in inland river systems

Mobilisation, alteration, and redistribution of monosulfidic sediments in inland river systems

Abstract:
The accumulation of monosulfidic sediments in inland waterways is emerging as a major environmental issue. Mobilisation and suspension of monosulfidic sediments can result in deoxygenation, acidification of the water column and mobilisation of trace metals. The controls on monosulfidic  sediment mobilisation and the critical thresholds for its scour and entrainment have not been established. This study examines the effect of a minor flood event (average return interval of 5 years) on sulfidic sediment scour in the Wakool River in southern NSW, Australia. Five profiles were sampled within a small (~300 m) reach before and after a minor flood event to determine the degree of sediment scour and transport. The results indicate substantial scour of both monosulfidic sediments and underlying bed sediments (approximately 2100 m3). Changes in the sediment geochemistry suggest large concentrations of monosulfidic sediments had been suspended in the water column, partially-oxidised and redeposited. This is supported by 210Pb results from one of the profiles. These results suggest that these monosulfidic sediments can move as bed load during minor flood events.

M.D. Cheetham, V.N.L. Wong, R.T. Bush, L.A. Sullivan, N.J. Ward, A. Zawadzki

Journal of Environmental Management 112 (2012) pp.330-339

http://dx.doi.org/10.1016/j.jenvman.2012.08.015

About The Author

Warwick Bishop
Warwick is a Director of Water Technology and has over 20 years of experience in surface water management. He has led a wide variety of projects covering areas such as flood risk management, water quality, sediment transport, coastal hazard, WSUD and environmental flows. Warwick has an Honours Degree in Civil Engineering from the University of Melbourne and a Masters of Engineering Science Degree from Monash University, investigating the detailed hydraulics of stormwater treatment wetlands. Warwick has experience throughout Australia in both rural and urban contexts. Since 2011 he has provided specialist input to the Flood Intelligence Unit of SES during both catchment and coastal flood emergencies. He is actively involved in Engineers Australia and is the current chair of the Victorian Water Engineering Branch Committee. Warwick has also contributed to the revision of Australian Rainfall and Runoff, with a particular focus on the application of flood models in urban areas.

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