Nitrogen loading resulting from major floods and sediment resuspension to a large coastal embayment

作者：Alistair Grinham, Tony Costantini, Nathaniel Deering, Cameron Jackson, Carissa J. Klein, Catherine E. Lovelock, John M. Pandolfi, Gal Eyal, Michael Linde, Matthew Dunbabin, Brendon Duncan, Nicholas Hutley, Ilha Byrne, Craig Wilson, Simon Albert · 发表于：The Science of The Total Environment · 年份：2024 · DOI：10.1016/j.scitotenv.2024.170646 · 被引用次数：22 · 研究领域：Coastal wetland ecosystem dynamics、Coastal and Marine Dynamics、Coastal and Marine Management

Major floods pose a severe threat to coastal receiving environments, negatively impacting environmental health and ecosystem services through direct smothering with sediment and nutrient loading. This study examined the short and long-term impacts of the February 2022 major flood event on mud extent and sediment nitrogen flux in Moreton Bay (the Bay), a large, sub-tropical embayment in Southeast Queensland, Australia. Short-term impacts were assessed three days after the flood peak by sampling surface water at 47 sites in the direction of the predominant circulation pattern. Longer-term impacts were assessed by undertaking an intensive sediment survey of 223 sites and a nutrient flux experiment using sediment core incubations to simulate calm and resuspension conditions for the four key sediment classes. Short-term impacts revealed elevated turbidity levels extended across the Bay but were highest at the Brisbane River mouth, ammonium concentrations varied inversely with surface turbidity, whereas nitrate concentrates closely tracked surface turbidity. The sediment survey confirmed fine sediment deposition across 98 % of the Bay. Porewater within the upper 10 cm contained a standing pool of 280 t of ammonium, with concentrations more than three orders of magnitude higher than overlying surface waters. The nutrient flux experiment revealed an order of magnitude higher sediment ammonium flux rate in the sandy mud sediment class compared to the other sediment classes; and for si...