
%0 Journal Article
%A Harris, Graham P. 
%T Biogeochemistry of nitrogen and phosphorus in Australian catchments, rivers and estuaries: effects of land use and flow regulation and comparisons with global patterns
%J Marine and Freshwater Research
%D 2001/02/14
%V 52
%N 1
%P 139-149
%K 
%R https://doi.org/10.1071/MF00031
%U https://www.publish.csiro.au/paper/MF00031 
%X This paper reviews the factors influencing the nitrogen (N) and phosphorus (P) exports from Australian catchments. Pristine, forested catchments export little N and P and the predominant form of N is dissolved organic nitrogen (DON). As catchments are cleared, exports increase and the predominant form of N changes from DON to dissolved inorganic N (DIN). Soluble reactive P (SRP) represents a roughly constant fraction of total P in these systems. As catchments are cleared, DIN:SRP export ratios increase sharply and DIN comes to represent a larger and larger fraction of the total N. The ratios of total N:P and DIN:SRP in rivers reflect land use and the residence times of the water. In Australian lakes and reservoirs, DON and total Kjeldahl N (TKN)are consumed and DIN is exported downstream. Australian freshwater systems with long residence times show stoichiometric evidence of N limitation, and the frequent occurrence of N-fixing cyanobacterial blooms. Despite TN:TP loading ratios equalling or exceeding Redfield stoichiometry, many Australian estuaries and coastal lagoons also show extensive evidence of rapid denitrification and N limitation. Coastal lagoons also have long water residence times (up to 1 year) and a high proportion of the N load is denitrified. 
