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Reconstructing the history of nutrient loads and sources in the Derwent Estuary, Tasmania, Australia, using isotopic fingerprinting techniques

Citation

Stevens, H and Chase, Z and Zawadzki, A and Wong, H and Proemse, BC, Reconstructing the history of nutrient loads and sources in the Derwent Estuary, Tasmania, Australia, using isotopic fingerprinting techniques, Estuaries and Coasts, 44, (8) pp. 2236-2249. ISSN 1559-2723 (2021) [Refereed Article]


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DOI: doi:10.1007/s12237-021-00919-0

Abstract

Carbon and nitrogen stable isotope analysis of estuarine sediment cores has proved useful for tracing nutrient sources and for assessing changes to nutrient loading through time. However, this technique has rarely been applied to estuaries in the Southern Hemisphere, despite the vulnerability of urban estuaries to excess nutrient loading and eutrophication because of mounting anthropogenic pressures. This study uses sediment core nutrient concentrations (total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP)) and stable isotope analysis (δ13C, δ15N, and δ34S) in combination with lead-210 (210Pb) dating, to reveal information about past and current nutrient loads and sources to various parts of the Derwent estuary, Tasmania, Australia. The upper estuary was found to experience periods of low dissolved oxygen levels and δ13C and δ15N values indicate that the nutrient sources to the upper estuary are predominantly riverine inputs and pulp and paper mill effluent. The middle estuary was found to have higher nutrient (TN and TP) concentrations than other Australian estuaries (Quibray Bay, Woolooware Bay, and Moreton Bay). Along the whole estuary there was a transition of predominantly terrestrial OM in upper estuary to predominantly marine OM in middle/lower estuary. However, there was a clear influence from a nitrogen source with an enriched δ15N value, likely wastewater treatment plant (WWTP) effluent. 3-endmember mixing analysis between terrestrial OM, marine OM, and WWTP effluent shows that WWTP effluent has contributed to up to 30.9% of sediment composition in the past—highlighting the significance of anthropogenic nutrient inputs, such as waste-water treatment plant effluent, to an urban estuary.

Item Details

Item Type:Refereed Article
Keywords:estuary, nutrient input, sediment, stable isotopes, eutrophication
Research Division:Environmental Sciences
Research Group:Pollution and contamination
Research Field:Environmental biogeochemistry
Objective Division:Environmental Management
Objective Group:Coastal and estuarine systems and management
Objective Field:Measurement and assessment of estuarine water quality
UTAS Author:Stevens, H (Mr Harrison Stevens)
UTAS Author:Chase, Z (Professor Zanna Chase)
UTAS Author:Proemse, BC (Dr Bernadette Proemse)
ID Code:150287
Year Published:2021
Web of Science® Times Cited:1
Deposited By:Oceans and Cryosphere
Deposited On:2022-06-06
Last Modified:2022-06-08
Downloads:0

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