Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
doi:10.5194/bg-2017-132
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
11 Apr 2017
Review status
This discussion paper is under review for the journal Biogeosciences (BG).
Effects of changes in nutrient loading and composition on hypoxia dynamics and internal nutrient cycling of a stratified coastal lagoon
Yafei Zhu1,2, Andrew McCowan2, and Perran L. M. Cook1 1Water Studies Centre, Monash University, Clayton, 3800, Australia
2Water Technology Pty Ltd, 15 Business Park Drive, Notting Hill, 3168, Australia
Abstract. The effects of changes in catchment nutrient loading and composition on the phytoplankton dynamics, development of hypoxia and internal nutrient dynamics in a stratified coastal lagoon system (the Gippsland Lakes) was investigated using a 3D coupled hydrodynamic biogeochemical water quality model. The study showed that primary productivity was equally sensitive to changed dissolved inorganic and particulate organic nitrogen loads, highlighting the need for a better understanding of particulate organic matter bioavailability. Stratification and sediment carbon enrichment are the main drivers for the hypoxia and subsequent sediment phosphorus release in the Lake King. High primary production stimulated by large nitrogen loading brought by winter flood contributed almost all the sediment carbon deposition (as opposed to catchment loads) which was ultimately responsible for summer bottom-water hypoxia. Interestingly, internal recycling of phosphorus was more sensitive to changed nitrogen loads than total phosphorus loads, highlighting the potential importance of nitrogen loads exerting a control over systems that become phosphorus limited (such as during summer nitrogen-fixing blooms of cyanobacteria). Therefore, the current study highlighted the need to reduce both TN and TP for water quality improvement in estuarine systems.

Citation: Zhu, Y., McCowan, A., and Cook, P. L. M.: Effects of changes in nutrient loading and composition on hypoxia dynamics and internal nutrient cycling of a stratified coastal lagoon, Biogeosciences Discuss., doi:10.5194/bg-2017-132, in review, 2017.
Yafei Zhu et al.
Yafei Zhu et al.
Yafei Zhu et al.

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