Tracing the sources of sediment and associated particulate nitrogen from different land uses in the Johnstone River catchment, Wet Tropics, north-eastern Australia

Mohammad Bahadori; Chengrong Chen; Stephen Lewis; Mehran Rezaei Rashti; Freeman Cook; Andrew Parnell; Maryam Esfandbod; Thomas Stevens

doi:10.1016/j.marpolbul.2020.111344

Tracing the sources of sediment and associated particulate nitrogen from different land uses in the Johnstone River catchment, Wet Tropics, north-eastern Australia

Mar Pollut Bull. 2020 Aug:157:111344. doi: 10.1016/j.marpolbul.2020.111344. Epub 2020 Jun 10.

Authors

Mohammad Bahadori¹, Chengrong Chen², Stephen Lewis³, Mehran Rezaei Rashti¹, Freeman Cook⁴, Andrew Parnell⁵, Maryam Esfandbod¹, Thomas Stevens³

Affiliations

¹ Australian Rivers Institute, Griffith University, Brisbane, QLD 4111, Australia; School of Environment and Science, Griffith University, Brisbane, Queensland 4111, Australia.
² Australian Rivers Institute, Griffith University, Brisbane, QLD 4111, Australia; School of Environment and Science, Griffith University, Brisbane, Queensland 4111, Australia. Electronic address: c.chen@griffith.edu.au.
³ Catchment to Reef Research Group, Centre for Tropical Water and Aquatic Ecosystem Research, James Cook University, Townsville, QLD 4811, Australia.
⁴ Australian Rivers Institute, Griffith University, Brisbane, QLD 4111, Australia; Freeman Cook & Associates Pty Ltd, Australia.
⁵ Hamilton Institute, Maynooth University, Ireland.

PMID: 32658700
DOI: 10.1016/j.marpolbul.2020.111344

Abstract

While the ecosystem of the Great Barrier Reef (GBR), north-eastern Australia, is being threatened by the elevated levels of sediments and nutrients discharged from adjacent coastal river systems, the source of these detrimental pollutants are not well understood. Here we used a combined isotopic (δ¹³C, δ¹⁵N) and geochemical (Zn, Pt and S) signatures and stable isotope analysis in R (SIAR) mixing model to estimate the contribution of different land uses to the sediment and associated particulate nitrogen delivered to the Johnstone River. Results showed that rainforest was the largest contributor of suspended and bed sediments in the river estuary (both 33.1%), followed by banana (26.7%, 20.4%), sugarcane (21.5%, 21.4%) and grazing (18.7%, 25.1%). However, bananas and sugarcane land uses had the highest contribution to sediments delivered to the coast per unit of area. This will help land managers to prioritise on-ground activities to improve water quality in the GBR lagoon.

Keywords: Fingerprinting; Geochemical signatures; Mixing models; Particulate nitrogen; Stable isotope.

MeSH terms

Australia
Ecosystem
Environmental Monitoring
Geologic Sediments
Nitrogen / analysis*
Phosphorus / analysis
Rivers*

Substances

Phosphorus
Nitrogen