Greedy Algae Reduce Arsenate

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Greedy Algae Reduce Arsenate

• Ferdi Hellweger(1)(2), Kevin Farley(3),
• Upmanu Lall(1) and Dominic Di Toro(2)(3)
• Stevens Institute of Technology
• Estuarine and Coastal Ocean Processes Seminar
  Series February 26, 2003

(1)
(2)
(3)
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Arsenic Speciation
Arsenate As(V)
Arsenite As(III)
Monomethylarsenic MMA
Dimethylarsenic DMA
Speciation affects transport and toxicity!
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Thermodynamics
TYPICAL OXYGENATED SURFACE WATERS
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Pacific Ocean (off Southern California)
Lake Biwa, Japan
Sohrin et al., Environ. Sci. Technol. 31 (1997)
Andreae, Deep-Sea Res. 25 (1978)
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Step 1 As(V) uptake by mistake
Yummy! P
Step 2 Reduction, methylation and excretion for
detoxification
Yak! As
As(V) ? As(III) ? MMA ? DMA
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Arsenic reduction takes place only when the
phytoplankton assemblage is in the log phase of
growth, therefore the spring bloom should
contribute a large majority of the reduced
arsenic species, with a smaller contribution from
the smaller fall bloom. Sanders and Windom
(1980)
Sanders and Windom, Estuarine Coastal Mar. Sci.
10 (1980)
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Lake Biwa, Japan
Sohrin et al., Environ. Sci. Technol. 31 (1997)
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Laboratory Batch Culture
Hasegawa et al., Chemosphere 43 (2001)
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• Literature supporting the observation
• River Beaulieu, UK (Howard et al., 1984)
• Southhampton Water, UK (Howard and Apte, 1989)
• Davis Creek Reservoir, CA (Anderson and Bruland,
  1991)
• Chesapeake Bay (Sanders and Riedel, 1993)
• Upper Mystic Lake, MA (Aurilio et al., 1994)
• Lake Biwa, Japan (Sohrin et al., 1997)
• Laboratory (Hasegawa et al., 2001)
• Literature contradicting observation
• Loch Ewe, Scotland (Apte et al., 1986)
• Lake Greifen, Switzerland (Kuhn and Sigg, 1993)
• Crowley Lake, CA (Kneebone and Hering, 2000)

Controlled batch experiment. Anderson and
Bruland, Environ. Sci. Technol. 25 (1991) Apte
et al., Mar. Chem. 20 (1986) Aurilio et al.,
Environ. Sci. Technol. 28 (1994) Hasegawa et
al., Chemosphere 43 (2001) Howard et al.,
Estuarine Coastal Shelf Sci. 19 (1984) Howard et
al., Appl. Organometal. Chem. 3 (1989) Kneebone
and Hering, Environ. Sci. Technol. 34 (2000)
Kuhn and Sigg, Limnol. Oceanogr. 38 (1993)
Sanders and Riedel, Estuaries 16 (1993) Sohrin
et al., Environ. Sci. Technol. 31 (1997).
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Proposed Mechanism (Hypothesis)
P-LIMITED
NOT P-LIMITED
DMA
DMA
DMA
DMA
PO4
P
PO4
P
MMA
As(V)
As(V)
As(V)
MMA
As(V)
As(III)
As(III)
As(III)
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Active Uptake
WATER
CELL
PO4
PO4
As(V)
As(V)
Only PO4
PO4 w/As(V)
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Uptake Competition
Sanders and Windom, Estuarine Coastal Mar. Sci.
10 (1980)
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Luxury Uptake
Under non P-limited conditions Algae up-regulate
their PO4 transport system to take up excess P.
Rhee, J. Phycol. 10 (1974)
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Luxury Uptake
Droop, J. Mar. Biol. Assoc. U. K. 55 (1975)
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Luxury Uptake
Hasegawa et al., Chemosphere 43 (2001)
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Effect of PO4 on As(V) Uptake Increasing PO4
causes less As(V) uptake (Sanders and
Windom, 1980). more As(V) uptake (Andreae and
Klumpp, 1979). less As(V) toxicity (Sanders,
1979). more As(V) toxicity (Fuhua et al.,
1994). This model accounts for antagonism
by competition. synergism by luxury uptake.
Andreae and Klumpp, Environ. Sci. Technol. 13
(1979) Fuhua et al., Toxicol. Environ. Chem. 41
(1994) Sanders, J. Phycol. 15 (1979) Sanders
and Windom, Estuarine Coastal Mar. Sci. 10 (1980).
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Excretion
Lean and Nalewajko, J. Fish. Res. Board Can. 33
(1976) Maeda et al., Appl. Organometal. Chem. 6
(1992).
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Methylation
As(III) ? MMA ? DMA
Intracellular speciation provides evidence for
faster methylation during stationary phase.
Suhendrayata et al., Appl. Organomet. Chem. 13
(1999) Goessler et al., Appl. Organometal.
Chem. 11 (1997).
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DMA
DMA
PO4
P
MMA
As(V)
As(V)
As(III)
As(III)
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Model
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• Conclusion
• Model application provides
• evidence for hypothesis.
• Current Focus
• Construct full lake model.
• Apply it to Lake Biwa,
• Davis Creek Reservoir
• and Upper Mystic Lake.
• More Information
• Presentation online at www.columbia.edu/flh23
• Paper to be submitted to Limnology
  Oceanography.
• thanks for your attention!!

Superpreliminary Lake Biwa DO calibration