2022 Early Hearing Detection & Intervention Virtual Conference
March 13 - 15, 2022
6/05/2017 | 3:15 PM - 3:30 PM | The importance of denitrification associated with macrophyte beds in reducing nitrate export from a subtropical river | 306A
The importance of denitrification associated with macrophyte beds in reducing nitrate export from a subtropical river
Denitrification in rivers can play a key role in reducing excessive nitrogen loading from catchments, removing up to 50%. This reduces coastal eutrophication and the likelihood of algal blooms. The presence of macrophyte beds enriches sediments with organic carbon thus promoting denitrification. However, there is limited knowledge of denitrification associated with macrophytes in subtropical rivers. To tackle this question we measured denitrification rates in sediment with and without macrophytes at six sites in the upper Brisbane River, Queensland, Australia. Using the isotope pairing technique we quantified the denitrification of water column nitrate diffusing into sediments and the rate of coupled nitrification-denitrification within sediments. Denitrification rates were 2-50 fold higher in macrophyte sediments compared to bare sediments at five of the sites. Sediments in macrophyte beds had a higher organic carbon content and lower porosity than bare sediments. Using this data we estimated the potential reduction in downstream nitrate transport possible under different macrophyte coverage scenarios. This work highlights the need to consider macrophyte cover when modelling nitrogen losses from catchments with implications worldwide. Additionally, understanding the environmental conditions controlling denitrification is important to guide river restoration to enhance nitrogen removal.
- C16 Restoration Ecology
- C09 Wetland Ecology
- C10 Biogeochemistry
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Presenters/Authors
Hannah Franklin
(), Australian Rivers Institute, Griffith University, Queensland, Australia, h.franklin@griffith.edu.au;
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Michele Burford
(), Australian Rivers Institute, Griffith University, Queensland, Australi, m.burford@griffith.edu.au;
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Kate Smolders
(), Seqwater, Queensland, Australia, k.smolders@seqwater.com.au;
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