Anthropogenic acceleration of sediment accretion in lowland floodplain wetlands, Murray-Darling Basin, Australia
- Authors: Gell, Peter , Fluin, J. , Tibby, John , Hancock, Gary , Harrison, Jennifer , Zawadzki, Atun , Haynes, Deborah , Khanum, Syeda , Little, Fiona , Walsh, Brendan
- Date: 2009
- Type: Text , Journal article
- Relation: Geomorphology Vol. 108, no. 1-2 (2009), p. 122-126
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- Description: Over the last decade there has been a deliberate focus on the application of paleolimnological research to address issues of sediment flux and water quality change in the wetlands of the Murray-Darling Basin of Australia. This paper reports on the research outcomes on cores collected from sixteen wetlands along the Murrumbidgee-Murray River continuum. In all sixteen wetlands radiometric techniques and exotic pollen biomarkers were used to establish sedimentation rates from the collected cores. Fossil diatom assemblages were used to identify water source and quality changes to the wetlands. The sedimentation rates of all wetlands accelerated after European settlement, as little as two-fold, and as much as eighty times the mean rate through the Late Holocene. Some wetlands completely infilled through the Holocene, while others have rapidly progressed towards a terrestrial state due to accelerated accretion rates. Increasing wetland salinity and turbidity commenced within decades of settlement, contributing to sediment inputs. The sedimentation rate was observed to slow after river regulation in one wetland, but has accelerated recently in others. The complex history of flooding and drying, and wetland salinisation and eutrophication, influence the reliability of models used to establish recent, fine-resolution chronologies with confidence and the capacity to attribute causes to documented effects. © 2008 Elsevier B.V.
- Description: 2003006710
Changes in the chemistry of sedimentary organic matter within the Coorong over space and time
- Authors: Krull, Evelyn , Haynes, Deborah , Lamontagne, Sebastien , Gell, Peter , McKirdy, David , Hancock, Gary , McGowan, Janine , Smernik, Ronald
- Date: 2009
- Type: Text , Journal article
- Relation: Biogeochemistry Vol. 92, no. 1-2 (2009), p. 9-25
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- Description: Like many other coastal systems across the world, the Coorong lagoonal ecosystem (South Australia) has degraded over the last 100 years; in this case as a result of extensive regulation and diversions of water across the Murray-Darling Basin following European settlement. To evaluate whether the sources of organic matter (OM) supporting its food-web have changed since the inception of water management and barrage construction, sedimentary OM was characterised in cores spanning the Coorong’s salinity gradient at depths representative of the last 100 years over which the management alterations to river and estuarine flow were most marked. Detailed 210Pb, 137Cs and Pu dating in conjunction with palaeolimnological data (Pinus pollen) allowed for the reconstruction of the timing of substantial changes observed in the composition of the OM, most of which occur during the early 1950s, concurrent with management-related variations in water flow and salinity. Negative shifts in