Ocean urea fertilization for carbon credits poses high ecological risks.
The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed.
Glibert
Patricia M
PM
University of Maryland Center for Environmental Science, Horn Point Laboratory, P.O. Box 775, Cambridge, MD 21613, USA. gilbert@hpl.umces.edu
Azanza
Rhodora
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Burford
Michele
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Furuya
Ken
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Abal
Eva
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Al-Azri
Adnan
A
Al-Yamani
Faiza
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Andersen
Per
P
Anderson
Donald M
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Beardall
John
J
Berg
G Mine
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Brand
Larry
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Bronk
Deborah
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Brookes
Justin
J
Burkholder
Joann M
JM
Cembella
Allan
A
Cochlan
William P
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Collier
Jackie L
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Collos
Yves
Y
Diaz
Robert
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Doblin
Martina
M
Drennen
Thomas
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Dyhrman
Sonya
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Fukuyo
Yasuwo
Y
Furnas
Miles
M
Galloway
James
J
Granéli
Edna
E
Ha
Dao Viet
DV
Hallegraeff
Gustaaf
G
Harrison
John
J
Harrison
Paul J
PJ
Heil
Cynthia A
CA
Heimann
Kirsten
K
Howarth
Robert
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Jauzein
Cécile
C
Kana
Austin A
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Kana
Todd M
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Kim
Hakgyoon
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Kudela
Raphael
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Legrand
Catherine
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Mallin
Michael
M
Mulholland
Margaret
M
Murray
Shauna
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O'Neil
Judith
J
Pitcher
Grant
G
Qi
Yuzao
Y
Rabalais
Nancy
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Raine
Robin
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Seitzinger
Sybil
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Salomon
Paulo S
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Solomon
Caroline
C
Stoecker
Diane K
DK
Usup
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Wilson
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Yin
Kedong
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Zhou
Mingjiang
M
Zhu
Mingyuan
M
D002244:Carbon / Q000737:chemistry*; D017753:Ecosystem; D005308:Fertilizers / Q000032:analysis*; D017752:Greenhouse Effect; D009792:Oceans and Seas; D014508:Urea / Q000737:chemistry* / Q000494:pharmacology*
D005308:Fertilizers; D002244:Carbon; D014508:Urea