The main source of excess nutrients, fine sediments and pesticides from Great Barrier Reef catchments is diffuse source pollution from agriculture.
Estimates of river pollutant loads to the Great Barrier Reef lagoon have greatly improved since the last Consensus Statement. The results confirm that water discharged from the catchments into the lagoon continues to be of poor quality in many locations. Furthermore, enhanced modelling and monitoring of total suspended solids, nitrogen, phosphorus and photosystem II inhibiting herbicides, and provenance tracing of sediment, has significantly enhanced our knowledge of major sources and processes contributing to these river pollutant loads. The main land uses contributing pollutant loads are rangeland grazing for sediment, rangeland grazing and sugarcane for total nitrogen and total phosphorus, and sugarcane for photosystem II inhibiting herbicides. The Wet Tropics, Burdekin and Fitzroy regions contribute most to these river pollutant loads.
Chapter 4 - Sources of sediment, nutrients, pesticides and other pollutants in the Great Barrier Reef catchment (PDF, 1.6 MB)
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