09 March, 2006
Phosphorus – Scarce Resource and Pollutant
Australian researchers have shown the usefulness of substance flow analysis as a tool for
supporting policy planning for conserving phosphorus reserves and, at the same time,
preventing it from being a pollutant.
Phosphorus (P) is an essential nutrient for crop and animal production. Over the last century, the
Earth’s P reserves have been intensively consumed by human activities, with fertiliser production
being the major (80%) driver of consumption. Nowadays, it is generally considered that, at the current
rate of consumption, phosphate reserves will last not more than one hundred years.
At the same time, the widespread use of P can be a cause of concern, especially when present in
excessive amounts in waterways. The enrichment of water bodies by P leads to eutrophication, now
one of the most common water quality impairments across EU.
The roles of P as a scarce resource and a major cause of eutrophication are usually assessed by
different research groups. However, in planning for phosphorus management, both roles of
phosphorus need to be considered.
In this context, Australian researchers have recently addressed both positive and negative values of P,
as a fertiliser and pollutant, in order to find the best strategy for P management. Using exhaustive
database collected from both published and unpublished Australian sources, the authors have
performed a substance flow analysis (SFA) in order to obtain an overview of current inputs, stocks,
and outputs of P in the Sydney region for the year 2000. Various scenarios for P management have
then been compared based on the SFA results. The main conclusions can be summarised as follows:
• Most of the P used in Sydney is imported from outside of the region under study. Since 80% of total
imported P occurs in food and detergent products, changing consumers’ behaviours is crucial for longterm reduction of P imports.
• Only 50% of the total P imports leave the area, meaning that P accumulates in the studied region.
Agriculture related sectors account for 97% of accumulated P, which raise question of how sustainable
the current agricultural practices are in term of fertiliser application.
• Over 90% of the exported P is in the form of treated wastewater discharge to the ocean. This
demonstrates the significant impact that either enhanced P removal or increased water recycling may
have on the flows of P. The combination of greywater recycling, composting toilet use, and changes in
dietary behaviour is the most effective scenario for both conserving P and preventing it from bcoming a
pollutant.
• The P discharge from wastewater treatment plants into the surface water bodies only constitutes a
small amount compared with the total P loads received by the surface waters. Most of P enters the
surface waters via run-off processes. As such, improved phosphate fertiliser application practices can
significantly reduce the amount of P reaching surface waters. Particularly effective options include P
separation at source enabling beneficial reuse for agricultural purposes.
This study demonstrates the effectiveness of SFA method as a tool for raising awareness of potential
environmental problems and for the assessment of alternate policy measures that may overcome the
perceived problem. However, it must be noted that despite the strengths that SFA possesses, it is
limited in that it deals only with one substance at a time and only with one particular area. Another
limitation of the SFA undertaken in this study is that it involves only static modelling assuming that the
P flows are invariable in time. In order to account for time dependence, dynamic modelling is required.
Source: Tangsubkul, N et al. (2005) ”Incorporating phosphorus management considerations into
wastewater management practices”, Environmental Science & Policy 8 : 1–15.
Contact: [email protected]
Theme(s): Agriculture, Waste
Opinions expressed in this News Alert do not necessarily reflect those of the European Commission
European Commission DG ENV
News Alert issue 13
March, 2006
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