State of the Environment

2006

Indicator: IW-12 Catchment nitrogen and phosphorus load

Data

Total phosphorus budgets (t/yr) by major region
Region Hillslope (PP) Gully (PP) Bank (PP) Point source (DP) Run-off (DP) Floodplain sedimentation (PP) Reservoir sedimentation (PP) Export (TP) Export % Times natural
Far North Qld 2 942 106 144 0 114 1 184 0 2 122 11 2.6
North Qld 3 966 129 187 155 158 1 292 140 3 163 17 2.3
Burdekin 11 909 1 271 309 0 178 8 185 2 960 2 522 13 5.9
Fitzroy 9 526 1 008 519 0 248 8 377 919 2 006 11 7
Moreton Bay 971 93 209 597 73 538 254 1 153 6 4.4
Qld South 2 426 336 277 53 164 1 748 362 1 146 6 4.4
Murray-Darling Basin 10 719 4 387 4 434 124 1 306 16 295 3 977 699 4 2.6
NSW North 987 277 396 5 199 572 10 1 282 7 3.6
NSW South 1 902 667 428 101 283 1 314 279 1 788 9 2.8
Vic East 207 183 216 4 266 303 13 559 3 1.5
Vic West 41 213 174 0 144 285 17 269 1 1.9
SA Gulf 146 204 78 9 152 309 19 262 1 2.3
WA South 53 1 009 299 146 569 1 254 17 805 4 2.6
Indian 46 342 111 0 81 466 0 115 1 6.5
Tasmania 244 87 358 137 303 73 25 1031 5 1.3
Totals/averages 46 086 10 312 8 138 1 331 4 240 42 194 8 992 18 921 100 2.8

TP is total phosphorus, PP is particulate (sediment-bound) phosphorus, DP is dissolved phosphorus. All loads are in tonnes per year (t/yr), and the export percent is the region export as a percentage of the assessment area total. Times natural is the network link-averaged increase in multiples of the pre-European load.

Source: National Land and Water Resources Audit 2001, Erosion and sediment transport, Land and Water Australia, Canberra, viewed 13 Apr 2005, http://audit.ea.gov.au/ANRA/land/land_frame.cfm?region_type=AUS®ion_code=AUS&info=soil_erosion, Table 6.2

Nitrogen budgets (t/yr) by major region
Region Hillslope PN Gully PN Bank PN Point source DN Run-off
DN		 Floodplain sedimentation
PN		 Reservoir sedimentation
PN		 Dentrification DN Export TN % Times natural
Far North Qld 15 457 425 575 0 2 487 5 826 0 190  12928 5 2
North Qld 15 789 515 746 175 3 486 5 123 559 174 14 854 6 2
Burdekin 33 615 5 084 1 234 0 3 915 23 528 7 695 2 359 10 266 12 4
Fitzroy 29 108 4 033 2 077 0 5 692 27 086 3 112 1 877 8 834 11 3
Moreton Bay 5 205 373 837 1 348 1 616 2 035 1 747 244 5 353 3 3
Qld South 9 179 1 346 1 108 49 3 646 6 501 1 290 714 6 822 4 2
Murray-Darling Basin 36 352 17 556 17 736 1 208 33 126 53 309 15 952 22 388 14 330 29 2
NSW North 7 759 1 108 1 583 0 4 511 3 682 38 427 10 815 4 2
NSW South 8 926 2 666 1 710 663 6 442 5 364 1 590 804 12 650 6 2
Vic East 1 500 731 865 253 5 897 1 222 39 699 7 285 3 1
Vic West 527 851 694 0 3 318 1 167 78 537 3 609 1 2
SA Gulf 905 815 313 31 3 975 1 294 65 1 349 3 332 2 3
WA South 982 4 038 1 196 694 15 282 4 481 57 5 250 12 404 6 3
Indian 445 1 368 444 0 2 032 1 972 0 1 016 1 301 1 3
Tasmania 1 536 348 1 432 518 6 774 369 255 170 9 815 3 1
Totals/averages 170 264 43 999 34 130 4 938 108 792 148 605 32 559 39 699 141 258 100 2

TN is total nitrogen, PN is particulate (sediment-bound) nitrogen, DN is dissolved nitrogen and all loads are in t/yr. Times natural is the network link-averaged increase in multiples of the natural load

Source: National Land and Water Resources Audit 2001, Erosion and sediment transport, Land and Water Australia, Canberra, viewed 13 Apr 2005, http://audit.ea.gov.au/ANRA/land/land_frame.cfm?region_type=AUS®ion_code=AUS&info=soil_erosion, Table 6.4

What the data mean

Major sources of nitrogen and phosphorus vary between river basins.

The dominant sources of phosphorus (over 50%) are: hillslope erosion in Queensland and New South Wales; gully and river bank erosion, and dissolved phosphorus in run-off in coastal Victoria, South Australia, Western Australia and Tasmania. In some basins, urban point source discharges are a principal cause (e.g. 30% of the total load for Moreton Bay).

Total nitrogen loads come mainly from hillslope erosion in Queensland and coastal New South Wales. Contributions from hillslope erosion and dissolved nitrogen loads in run-off in the Murray-Darling Basin are comparable in magnitude. Over 60% of the total load occurs as dissolved run-off in coastal Victoria, South Australia, Tasmania and much of Western Australia.

The major sink for phosphorus and nitrogen is floodplain sedimentation, but reservoir sedimentation (for both nitrogen and phosphorus) and riverine denitrification (for nitrogen only) can account for significant proportions.

Nearly 19,000 tonnes of total phosphorus and 141,000 tonnes of total nitrogen are predicted to be exported down rivers to the coast each year from areas of intensive agriculture: highest exports occur in the Far North, northern Queensland, Moreton Bay and coastal New South Wales.

Annual total phosphorus loads in river networks averaged nearly 3 times higher than estimates for pre-European settlement levels. Average annual total nitrogen loads were estimated to be more than double pre-European settlement levels.

Data Limitations

NLWRA 2001 data has not been updated.

Issues for which this is an indicator and why

Inland Waters - Catchment scale influences - Land and vegetation condition - Nutrients and sediments - sources and loads 

Quantities of nitrogen and phosphorus concentrating in surface water catchments are a direct measure of this pressure.

Other indicators for this issue:

Land - Contributions and pressures between the land and inland water - Pressures of changes to the land on inland waters 

Agricultural land use disturbs soils and can change loads of nitrogen and phosphorus entering inland waters, placing pressure aquatic species as well as on terrestrial species that rely on the water source. Quantities of nitrogen and phosphorus concentrating in surface water catchments are a direct measure of this pressure.

Other indicators for this issue:

Land - Contributions and pressures between the land and the ocean - Pressures of land changes on the coasts and oceans 

Agricultural land use disturbs soils and can change loads of nitrogen and phosphorus entering inland waters and ending up in coastal waters where in can place pressure aquatic and estuarine species as well as on other coastal species that rely on the water source. Quantities of nitrogen and phosphorus concentrating in surface water catchments are a direct measure of this pressure.

Other indicators for this issue:

Coasts and Oceans - Direct pressure of human activities on coasts and oceans - Direct pressure of coastal activities (other than shipping and fishing) 

Agricultural land use disturbs soils and can change loads of nitrogen and phosphorus entering inland waters and ending up in coastal waters where in can place pressure aquatic and estuarine species as well as on other coastal species that rely on the water source. Quantities of nitrogen and phosphorus concentrating in surface water catchments are a direct measure of this pressure.

Other indicators for this issue:

Coasts and Oceans - Contributions and pressures between the coasts and oceans and inland water - Effect of changes in inland waters on the coasts and oceans 

Nitrogen and phosphorus loads carried by inland waters can end up in coastal waters where in can place pressure aquatic and estuarine species as well as on other coastal species that rely on the water source. Quantities of nitrogen and phosphorus concentrating in surface water catchments are a direct measure of this pressure.

Other indicators for this issue:

Coasts and Oceans - Contributions and pressures between the coasts and oceans and land - Effects of changes in the land on the oceans 

Sediments and nutrients from the land can place pressure on coastal and estuarine waters.

Other indicators for this issue:

Inland Waters - Habitat scale influences - Water Quality (for surface and groundwater) - Sediment and turbidity 

Nitrogen and phosphorous may can enter waterways via sedimentation. Sediments can disrupt aquatic habitats and increase turbidity. Quantities of nitrogen and phosphorus concentrating in surface water catchments are an indirect measure of this pressure.

Other indicators for this issue:

Inland Waters - Response of biota - Bacteria and algae 

Increased nitrogen and phosphorus may lead to algal blooms. Quantities of nitrogen and phosphorus concentrating in surface water catchments are a measure of the likelihood of this pressure occurring.

Other indicators for this issue:

Biodiversity - Pressures on biodiversity - Pressures on marine biodiversity: pressures of coastal activities 

In addition to placing pressure on freshwater biodiversity, nitrogen and phosphorus loads reaching the coasts, place pressure on coastal and marine biodiversity.

Other indicators for this issue:

Human Settlements - Pressures created by human settlements on the environment - Waste 

Nitrogen sources in landscapes come from fertiliser use and application, animal wastes and sewage discharges. Sewage discharges are main source of this pressure originating from human settlements. Phosphorus is the key limiting element in freshwaters and is mostly tightly bound to particulate material. There are local problems with phosphorus enrichment in urban rivers arising from direct discharges, storm runoff, sewer overflows and septic tank infiltration. Quantities of nitrogen and phosphorus concentrating in surface water catchments are a direct measure of this limitation on human water supply and of the impact of human use on the land, inland waters, biodiversity and the coasts and oceans.

Other indicators for this issue:

Further Information

Australian Catchment, River and Estuary Assessment 2002

ABS:

Brisbane, Burdekin, Herbert, H-Nepean, Yarra, Swan, Fitzroy Rivers

Key

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