Substance flow analysis of phosphorus within New Zealand and comparison with other countries.

Phosphorus (P) is an essential and non-renewable resource that is estimated to be depleted within the next 70-140 years. Increasing P scarcity and environmental pollution requires the development of a proper P management system. One fundamental step is to understand how P flows within society. Thus, a substance flow analysis (SFA) of P was conducted to distinguish and quantify different P flows within New Zealand, and principal component analysis (PCA) was used to show where the P flow in New Zealand was significantly different from the most efficient P utilization countries. Aside from having low P recovery, New Zealand imports a significant amount of P, while re-exporting a much smaller fraction of it compared with other countries, resulting in a high accumulation. The SFA analysis showed that although diffuse sources of P pollution pose a greater environmental risk to water bodies, promoting P recovery from point sources of pollution, such as from waste treatment facilities and landfill sites, would still improve the P management efficiency in New Zealand, which could decrease the annual P rock imports by 20%.