8/6/2019 Phosphorus: Approaching Fundamental Limits?
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editorialSTockHoLM WATEr PrIzE LAUrEATE
Phosphorus, like reshwater, is essential orlie and has no
substitutes. All living organ-isms require phosphorus to carry
geneticinormation and process energy. Phosphorusis a key
constituent o bones. Phosphorusis also an important pollutant o
reshwa-ter. Phosphorus is the principal driver oalgae blooms that
cause toxicity, oxygenloss, sh kills and other problems in
lakes,reservoirs, and rivers. All o the phosphorusthat acts as a
water pollutant comes romagriculture. Most o the phosphorus
pollu-tion comes directly in erosion and runof
rom agricultural elds. Some o the phos-phorus pollution comes
rom human wastethat is untreated or insufciently treated,and o
course this phosphorus derives romood produced by agriculture. Yet,
phos-phorus or ertilising croplands is lackingin some parts o the
world. According tosome analyses, humanity is approachingpeak
phosphorus, the time when globalreserves o mineable phosphorus
begin todecline. How has a limiting actor or liebecome a serious
pollutant?
Phosphorus enters the biosphere whenrocks become soil. Natural
weathering orocks adds only a small amount o phospho-rus to the
biosphere each year. Mining orphosphorus used in ertilisers
accounts orthe vast majority o phosphorus added tothe biosphere
each year. Mining phosphorusis relatively new in geologic history;
almostall o the phosphorus mining has occurredsince about 1950.
Five countries China,Morocco, South Arica, Jordan and theUnited
States produce about 90 per cento the worlds mined phosphorus.
Mined phosphorus is added to soil tostimulate crop growth.
Currently, a bit morethan a third o global crop production is edto
livestock. Manure is rich in soluble orms
o phosphorus that are readily transportedin water. Tus runof o
phosphorus romertiliser and manure has become a majorpollutant o
reshwater in phosphorus-richparts o the world.
Te maximum amount o mined phos-phorus that can be applied to
earths soils
without triggering toxic algae blooms isknown as the planetary
boundary or phos-phorus. Global phosphorus application ratesar
exceed the planetary boundary, indicatingthat phosphorus pollution
is a problem oglobal concern.
Although the world applies too muchphosphorus on average,
phosphorus appli-cation varies widely rom place to place.In North
America and Western Europe,applications o ertiliser and manure
havesubstantially enriched soils with phosphorusand thereby caused
massive pollution prob-
lems. Arica is rich in mineable phosphorusreserves, but more
than 95 per cent o thephosphorus mined in Arica is exported toother
countries. Aricas soils have the lowestertiliser application rates
in the world, andmost Arican soils are phosphorus-defcient.
Earths supply o mined phosphorus isrunning out, even as demand
or phosphorusgrows at around three per year. Existingmines are
degrading, as miners are orced todig deeper and extract
phosphorus-bearingrock o lower quality. Some studies indicate
that Peak Phosphorus, the time when sup-plies cannot meet
demand, is only a ewdecades away. Other studies argue that thepeak
is past, while still others say it is centu-
ries away. While projections are debatable,it is certain that
phosphorus is an exhaust-ible resource with no substitutes.
Shortageswill occur.
Ironically, phosphorus is a dwindlingresource that is a major
pollutant. Roughly80 per cent o mined phosphorus is neverconsumed
as ood by humans. Instead it iswasted and thereby causes massive
damageto reshwaters.
Conservation is an obvious solution towaste o phosphorus.
Phosphorus can be con-served on the arm, in ood distribution
and
consumption, and in treatment o humanwaste. On the arm,
phosphorus applica-tions should match crop needs, and erosiono
phosphorus-rich soil should be minimised.
Animal production is a major driver o excessphosphorus
application, when manure is ap-plied to soil as a waste product.
reatment
technologies that ex-tract phosphorus romanimal waste in
useulorms can decrease thisloss. Liestyle changes
that decrease meatconsumption also decrease phosphoruswaste.
Finally, human waste contains a greatdeal o phosphorus that can be
recycled oruse as ertiliser.
Phosphorus, like reshwater, is a non-substitutable resource that
is in short sup-ply. Wasted phosphorus becomes a majorpollutant o
reshwaters associated withtoxic blooms o algae, oxygen
depletion,fsh kills, disease outbreaks and other seri-ous problems.
By recognising that phos-phorus is a rare and dwindling
resource
that should be careully conserved, we winin two ways: we
maintain the supply o acritical mineral ertili ser, and we
maintainclean reshwater.
Approaching Fundamental Limits?
...humanity is approachingpeak phosphorus
Phosphorus:
Pfess Stephen r. capente f theUnivesity f Wisnsin-Madisn,
the2011 Sthlm Wate Pie Laueate.
JeffMiller,UniversityWisco
nsin-Madison
Professor Stephen R. Carpenter of the University of
Wisconsin-Madison wasnamed the 2011 Stockholm Water Prize Laureate
for his outstanding researchon lakes. In this exclusive editorial,
he presents an argument for phosphorusmanagement.
8/6/2019 Phosphorus: Approaching Fundamental Limits?
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editorialSTockHoLM WATEr PrIzE LAUrEATE
FURtheR ReadIng
Reconsideration of the planetary
boundary for phosphorus.
Envinmental reseah Lettes
6:014009. capente, S. r. and
E. M. bennett. 2011.
Sustainability Challenges of Phos-
phorus and Food: Solutions from
Closing the Human PhosphorusCycle. bisiene 61:117-124.
childes, D. L., J. cman,
M. Edwads, and J. J. Else. 2011.
The story of phosphorus: Global
food security and food for thought.
glal Envinmental chane
19:292-305. cdell, D., J.-o. Dan-
et, and S. White. 2009.
Peak phosphorus. Foreign Policy
(www.feinpliy.m, nline
22 Apil 2010). Else, J.J. and S.White. 2010.
Photo:Image100Ltd.
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