Chemistry of tropospheric tropospheric OH and HO OH and HO 2 - - PowerPoint PPT Presentation

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Chemistry of Chemistry of tropospheric tropospheric OH and HO OH and HO2

2 radicals:

radicals: Current understanding and questions Current understanding and questions

Yugo Kanaya

(Frontier Research Center for Global Change, JAMSTEC)

July 21, 2007 CITES-2007 conference, Tomsk, Russia Acknowledgments: my participation in CITES-2007 is funded by APN

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Importance of Importance of OH and HO OH and HO2

2

to atmospheric chemistry and climate to atmospheric chemistry and climate

▶ sink of anthropogenic/natural gases

(NOx, SO2, CO, hydrocarbons etc.）

▶ sink of CH4 and HCFCs

CH4 + OH products HCFC + OH products

▶ Production of acidic species/aerosols

SO2 + OH

• ・・・
• H2SO4

▶ Catalytic production of tropospheric ozone

cleansing capacity global warming regional/hemispheric pollution acidification

OH HO2

CO

NO NO2 O3

hν, H2O hν, O2

O3 (n>1) n n n n

3

Tropospheric Tropospheric OH known OH known

• nly since
• nly since

1969 1969

Weinstock, 1969

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Current understanding of Current understanding of OH and HO OH and HO2

2 chemistry

chemistry

• Reactive, but not too reactive (do not react with O2)
• Short lifetime (<1 s for OH, <100 s for HO2)
• Regeneration via catalytic reactions
• Concentration levels

OH: 106-107 radicals cm-3, or ~0.1 pptv or ~1x10-13 v/v HO2 : 108- 109 radicals cm-3, or 10 pptv

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Behavior of OH and HO Behavior of OH and HO2

2 (1)

(1)

• Diurnal variations
• Non-linear behavior with NOx

Logan et al., 1981 Logan et al., 1981

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Behavior of OH and HO Behavior of OH and HO2

2 (2)

(2)

• Seasonal variations, geographical distributions of OH

Spivakovsky et al., 2000 Unit: 105 cm-3

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Current understanding of Current understanding of OH and HO OH and HO2

2 chemistry

chemistry

Key question: Key question: Any other important reactions controlling OH and HO Any other important reactions controlling OH and HO2

2 concentrations?

concentrations? Our approach: Our approach: Direct measurements of OH and HO Direct measurements of OH and HO2

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Comparison with modeled concentrations: Test the mechanisms Comparison with modeled concentrations: Test the mechanisms

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In In-

• situ measurement techniques of OH

situ measurement techniques of OH

See Heard and Pilling, 2003 for more details

• 1. Leeds Univ., UK
• 2. Forschungszentrum Juelich, Germany
• 3. Pennsylvania State Univ., USA
• 4. FRCGC/JAMSTEC, Japan
• 5. Max Planck Institut, Germany
• 1. Forschungszentrum Juelich, Germany
• 1. NCAR, USA
• 2. DWD, German Weather Service, Germany
• 3. Georgia Inst. Tech., USA

Groups actively reporting observations in 2000s Laser-induced fluorescence (LIF) at low pressure Differential optical absorption spectroscopy (DOAS) Chemical Ionization Mass Spectrometry (CIMS) method

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CIMS CIMS（ （Chemical Ionization/ Chemical Ionization/ mass spectrometry mass spectrometry） ）

OH + 34SO2 + M H34SO3 + M H34SO3 + O2

34SO3 + HO2 34SO3+ H2O + M

H2

34SO4 + M

NO3

• ・HNO3 + H2

34SO4

• H34SO4
• ・ HNO3 + HNO3

Tanner et al., 1997 Highly sensitive but calibration needed

10cm diameter Quartz tube inlet 185nm for calibration Hg lamp NO3

• ・HNO3

34SO2

H2

34SO4

H34SO4

• ・ HNO3

QMS OH

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LP LP-

• DOAS (long

DOAS (long-

• path differential optical absorption

path differential optical absorption spectroscopy spectroscopy） ）

Dorn et al., 1995

( ) ( ) ( ) [ ] ( ) ( )

λ λ 1 OH λ σ λ λ ln I I l I I − ≈ ⋅ ⋅ =

σ(λ)~1x10-16 (cm2), l=3x105 (cm), [OH]=1x106 (cm-3)

• absorbance~3x10-5 calibration not needed

spectro graph Dye laser Free atmosphere

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LIF instrument LIF instrument to measure OH/HO to measure OH/HO2

2

8kHz 190ns 490ns

Kanaya et al., J. Atmos. Chem., 2001. Kanaya and Akimoto, The Chem. Record, 2002 Kanaya and Akimoto, Appl. Opt., 2006

Detection limit @1min.: 2x105 cm-3 or 0.008 pptv (or 8x10-15 v/v) Calibration uncertainty: ±20% (OH), ±22% (HO2)

HO2 + NO OH + NO2

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Field observations of OH and HO Field observations of OH and HO2

2 in Japan

in Japan

Conventional instruments, spectroradiometer T, RH (H2O), Pressure, J values Denuder, PTR-MS HCHO, CH3CHO,

• ther oxygenated
• rganic compounds

(OVOC) GC-NICIMS PANs GC-FID, PTR-MS NMHCs (C2-C7) chemiluminescence NO, NO2, NOy NDIR CO UV absorption O3 technique Chemical species

Photochemical box model

(Regional Atmospheric Chemistry Mechanism, 77 species, 237 reactions)

Modeled [OH], [HO2]

(99, 7 (99, 7-

• 8)

8) (00, 6) (00, 6) (03, 9) (03, 9) (98, 7 (98, 7-

• 8)

8) (04, 1 (04, 1-

• 2)

2) (04, 7 (04, 7-

• 8)

8)

Direct measurement of [OH], [HO2]

Colors: NO2 column density (SCIAMACHY)

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OH and HO OH and HO2

2:

: Rishiri Rishiri Island Island

Kanaya et al., JGR, 2007a

2 4 6 8 10 12 14 [HO2] (pptv) 18 19 20 21 22 23 24 25 26 27 28 29 2x10 6 4x10 6 6x10 6 8x10 6 107 Day of September 2003 [OH] (cm-3)

• bs.

model

18 19 20 21 22 23 24 25 26 27 28 29 2x10 6 4x10 6 6x10 6 8x10 6 107 Day of September 2003 [OH] (cm-3)

Model constrained by HO2(obs.)

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[ [HOx HOx] at coastal sites: ] at coastal sites:

5 10 15 20 25 5 10 15 20 25

[HO2] (pptv)

2 4 6 8 10 12 14 16 18 20 22 0 5 10 15 20 25 Time of day OKI

• Aug. 6, 1998

OKINAWA

• Aug. 14, 1999

RISHIRI

• Jun. 25, 2000

calc.

• bs.

Sommariva et al., 2004 (Cape Grim)

4e+8 2e+8, ~8 ppt

Feb.15 Feb.16 [HOx] (cm-3) Kanaya and Akimoto, 2002

Obs. model

Missing HO2 sink:

• 1. HO2 + aerosol reactions
• 2. Iodine chemistry

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• 1. Heterogeneous chemistry?
• 1. Heterogeneous chemistry?

aerosol (aqueous particle) HO2 Taken up with the probability of 100% (b) Molecular Dynamics (MD) calculations on pure water surface (Morita, Kanaya, and Francisco, JGR, 2004) (a) Laboratory experiments with CuSO4-doped aqueous particles : γ~ α > 0.5 (Mozurkewich et al., 1987) α=497/500 =0.994

accommodated accommodated accommodated

scattered

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Including heterogeneous Including heterogeneous loss in the model loss in the model

HO2 lost on aerosol : kγ

1 10 100 1000 10000 1 10 100 1000 diameter (nm) dN/ dlogD

SMPS OPC

• bs.

model

2 4 6 8 10 12 14 [HO2] (pptv)

• 1. HO2 + aerosol reactions

18 19 20 21 22 23 24 25 26 27 28 29

Kanaya et al., JGR, 2007a

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at Mace Head, Ireland, (Hebestreit, 2001)

• 2. Iodine chemistry?
• 2. Iodine chemistry?

19 23 24 25 26 27 28 29 10 20 30 40 day of September 2003 required IO (pptv)

Assuming γ(HOI)=0.5 Required IO: 10 -25 pptv

20 26 27 28 29 30 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 50 100 150 200

day of July/August 2004 [O3] (ppbv)

Tokyo in summer 2004: clean & smog periods Tokyo in summer 2004: clean & smog periods

Clean Smog

(persistent southerly wind) (land-sea breeze)

air quality standard

Aug.9 14:50

• Aug. 12 12:50

O3: 114 ppbv O3: 31 ppbv

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Composite diurnal variations in Tokyo Composite diurnal variations in Tokyo

0 2 4 6 8 10 12 14 16 18 20 22 0 10 20 30 40 50 60 70 Time of day (hour) [HO2] (pptv) 0.5 1 1.5 2 2.5 3 3.5 [HO2] (pptv)

• 2x106
• 1x106

0x106 1x106 2x106 3x106 4x106 5x106 [OH] (cm-3) 0 2 4 6 8 10 12 14 16 18 20 22 0

• 5x106

0x106 5x106 1x107 1.5x107 2x107 Time of day (hour) [OH] (cm-3)

(a) winter HO2 (b) winter OH (c) summer HO2 (d) summer OH

1.1 pptv 5.7 pptv 1.5x106cm-3 6.3x106cm-3

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OH, HO OH, HO2

2 comparisons winter 2004, Tokyo

comparisons winter 2004, Tokyo

20 21 22 23 24 25 26 27 28 29 0x100 2x106 4x106 6x106 [OH] (cm-3) 29 30 31 1 2 3 4 5 6 7 20 21 22 23 24 25 26 27 28 29

• 1

1 2 3 4 5 6 [HO2] (pptv) 29 30 31 1 2 3 4 5 6 7 Day of January/February 2004

• bs.

[HO2] (pptv) Day of January/February 2004 20 21 22 23 24 25 26 27 28 29 0x100 2x106 4x106 6x106 [OH] (cm-3) 29 30 31 1 2 3 4 5 6 7 20 21 22 23 24 25 26 27 28 29

• 1

1 2 3 4 5 6 [HO2] (pptv) 29 30 31 1 2 3 4 5 6 7 Day of January/February 2004

model

Kanaya et al., JGR accepted, 2007b

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• bs

26 27 28 29 30 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

• 2x106

2x106 4x106 6x106 8x106 107 1.2x10 7 1.4x10 7 [OH] (cm-3)

OH, HO OH, HO2

2 comparisons: summer 2004, Tokyo

comparisons: summer 2004, Tokyo

OH HO2

26 27 28 29 30 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 10 20 30 40 50 60 [HO2] (pptv)

• bs

model model

Day of July/August 2004

Kanaya et al., JGR accepted, 2007b

24 1 10 100 0.01 0.1 1 10 [HO2] (pptv)

(b)

1 10 100 0.1 1 10 100 [NO] (ppbv) k[HO2][NO] (ppbv h-1) (a) winter

HO HO2

2 at high [NO] during winter

at high [NO] during winter

( 0900-1500 LST)

2 4 6 8 10 12 14 16 18 20 22 0 2 4 6 8 10 12 14 time of day (hour) F-D(Ox) (ppbv h-1)

model HOx

• meas. HOx
• bs

model

• bs

model [HO2] k[HO2][NO] F-D(Ox): net photochemical production rate of Ox

Ox := NO2 + O3,

F-D(Ox) = k[HO2][NO] + Σki[RO2]iφi[NO] – k’[O1D][H2O] – k”[OH][O3] – k’”[HO2][O3] – Σkj[olefin]j[O3] – k””[OH][NO2] F-D(Ox)

Kanaya et al., JGR revised, 2007c

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k[HO k[HO2

2][NO] vs. [NO] in other studies

][NO] vs. [NO] in other studies

Saturation observed (Mexico City) Shirley et al., 2005

(meas. HO2) (model HO2) (model HO2) (meas. HO2)

Saturation NOT observed (NYC) Ren et al., 2003 just increase! Peak present

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• 1. Misunderstood HNO
• 1. Misunderstood HNO4

4 chemistry?

chemistry?

20 21 22 23 24 25 26 27 28 29 30 31 1 2 3 4 5 6 7 0.001 0.01 0.1 1 10 100 1000

day of January/February 2004 [HO2] or [HNO4] (pptv)

HNO4 (run 2) HO2 (run 2) HNO4/HO2 ratio calculated to be as high as 100!! HO2 + NO2 HNO4 HNO4+OH NO2 + O2 + H2O Unknown reactions of HNO4?

• HNO4 + NO

2HOx (or HONO) could explain the trend.

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• 2. Unknown
• 2. Unknown HOx

HOx source linearly source linearly scalable with [NO]? scalable with [NO]?

• Base model run
• model run with

additional HOx source at a rate of [NO]x2x10-5

1 10 100 0.1 1 10 [NO] (ppbv) Model/obs. ratio of [HO2] (a) O3+ olefin reactions 1.1 ppbv (roughly 2.7 x 1010 cm–3) of missing olefin + ozone at 30 ppbv (roughly 7.5 x 1011 cm–3), at 2.5 x 10–16 cm3 molecule–1 s–1 and a radical quantum yield of 2 (b) Carbonyl photolysis Direct emission of carbonyl species that rapidly photodissociate to give HOx 500 pptv of a carbonyl species that photolyzes rapidly (J value = 4 x 10–4 s–1 )

Kanaya et al., JGR revised, 2007c

28 1 10 0.1 1

NO (ppbv) NMHCs (ppmvC) (d) F-D(Ox) (ppbv h-1) 6.81-10.0 4.64-6.81 3.16-4.64 2.15-3.16 1.47-2.15 1.0-1.47 0.681-1.0 0.464-0.681 0.316-0.464 0.215-0.316 0.147-0.215 0.10-0.147

F F-

• D(Ox

D(Ox) as ) as functions of NO functions of NO and and NMHCs NMHCs

contour: using model HO2 dots: using obs. HO2 (0900-1450)

winter

1 10 0.1 1

NO (ppbv) NMHCs (ppmvC) (d) F-D(Ox) (ppbv h-1)

1 10 0.1 1

NO (ppbv) NMHCs (ppmvC) (d) F-D(Ox) (ppbv h-1) 6.81-10.0 4.64-6.81 3.16-4.64 2.15-3.16 1.47-2.15 1.0-1.47 0.681-1.0 0.464-0.681 0.316-0.464 0.215-0.316 0.147-0.215 0.10-0.147

NOx-limited VOC-limited

• bs.

: NO ) D(Ox) F ( model : NO ) D(Ox) F ( > ∂ − ∂ < ∂ − ∂

ppbv h-1

Kanaya et al., JGR revised, 2007c

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lost

Aerosol surfaces

HOI

hν IO

lost

Heterogeneous reaction

HO2-H2O

Unknown reaction

• lefins

+O3

HO2NO2

Unknown reaction

HONO

hν

Summary and current questions Summary and current questions

• Daytime OH and HO2 concentrations: normally predicted by the model to within a factor of 2.
• However, more precise description is necessary to better predict global warming, acidification,

and pollution etc.

• More field, laboratory, and model studies are necessary to improve our understanding of OH and

HO2 chemistry.

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LIF(Jülich) LIF(FRCGC) LIF(MPI) LIF(Leeds) CIMS (DWD) DOAS(Jülich)

Phase 1: ambient measurements 09- 11, July 2005 Phase 2: using SAPHIR (outdoor chamber) 17- 23, July 2005

HOxCOMP2005 HOxCOMP2005: International blind

intercomparison of OH measurement (Jülich,

Germany）

Dorn et al., in prep. etc.

■ DOAS ○ LIF

Hofzumahaus et al., 1998

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In In-

• situ measurements of HO

situ measurements of HO2

2

Heard and Pilling, 2003

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• 2. Iodine chemistry?
• 2. Iodine chemistry?

NO vs. calc/ NO vs. calc/obs

• bs ratio

ratio

1 10 100 1000 10000 0.1 1 10 NO (pptv) 0.1 1 10

• calc. / obs. ratio

(a) HO2 (b) OH

1 10 100 1000 10000 0.1 1 10 NO (pptv) 0.1 1 10

• calc. / obs. ratio

(a) HO2 (b) OH

iodine chem.

2000.6 2000.6 HOI lost

?

HOI lost +hν +IO

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• 2. HO
• 2. HO2

2+RO

+RO2

2 reactions faster?

reactions faster?

Aloisio and Francisco, 1998

• 1. HO2 + HO2 reaction:

Correction term: 1 + 1.4 × 10–21 [H2O]exp(2200/T).

• 2. HO2 + NO2 reaction rate

coefficient also depends on [H2O] Any other reactions accelerated by [H2O]?

2 4 6 8 10 12 14 [HO2] (pptv) 2 4 6 8 10 12 14 [HO2] (pptv)

model (w/ HO2+aerosol reaction) model (faster HO2 + RO2 reactions (x5)) 18 19 20 21 22 23 24 25 26 27 28 29 Day of September 2003

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26 27 28 29 30 31 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 10 20 30 40 day of July/August 2004 net O3 prod. rate (ppbv h-1) with meas. HO2 with calc. HO2

Net production rate of Ox: F Net production rate of Ox: F-

• D(Ox

D(Ox) )

Ox := NO2 + O3,

F-D(Ox)= {k[HO2] + Σki[RO2]iφi}[NO] – k’[O1D][H2O] – k”[OH][O3] – k’”[HO2][O3] – Σkj[olefin]j[O3] – k””[OH][NO2]

• HO2obs. or HO2calc.

Averaged maxima: 11.2, 13.1 ppbv h-1, not significantly high during smog period Smog period

(land-sea breeze)

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50km

0-20 ppb 21-40 ppb 41-60 ppb 61-119 ppb 120-239 ppb >240 ppb

2004/08/09 15:00

Wind field

O3

0.20-3.9 m/s 4.0-6.9 m/s 7.0-9.9 m/s 10.0-12.9 m/s 13.0-14.9 m/s >15.0 m/s Data from AEROS monitoring network (JEM)

O O3

3 builds up in downwind area in

builds up in downwind area in “ “clean clean” ” period period

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Composite diurnal variation of F Composite diurnal variation of F-

• D(Ox

D(Ox) )

winter summer Day integral of F-D(Ox): 50, 38 ppb (winter) 92, 91 ppb (summer) Ozone production in summer is only <2.5 times higher than in winter

2 4 6 8 10 12 14 16 18 20 22 0 2 4 6 8 10 12 14 time of day (hour) F-D(Ox) (ppbv h-1)

model HOx

• bs. HOx

2 4 6 8 10 12 14 16 18 20 22 0 2 4 6 8 10 12 14 time of day (hour)

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missing HO missing HO2

2 loss rate: HO

loss rate: HO2

2

• lost :k (s

lost :k (s-

• 1

1)

)

23-Sep 24-Sep 25-Sep 26-Sep 27-Sep 28-Sep 29-Sep 0.005 0.01 0.015 0.02 0.025 missing HO2 loss rate (s-1) missing loss rate

0.34 measured Temperature 0.35 measured CHBr3 0.41 modeled CH3COOOH 0.42 measured Wind speed, m/s 0.45 measured OH 0.46 modeled CSL (cresol etc.) 0.48 measured HO2 0.49 assumed HCHO 0.49 measured Transmission factor 0.34–0.69 modeled RO2 0.68–0.71 measured J values 0.72 modeled O1D R Type Species/Parameter R Type Species/Parameter 0.22 measured Particles (300–500 nm) 0.22 measured H2O 0.27 reported

• (Tidal height)

0.30 measured CH3Cl 0.31 measured CH3I 0.32 measured CO 0.33 modeled GLY (glyoxal etc.)

Missing HO2 sink:

• 1. HO2 + aerosol reactions
• 2. Iodine chemistry

38 2x106 4x106 6x106 8x106 1x107 2x106 4x106 6x106 8x106 1x107 [OH] obs. (cm-3) [OH]model (cm-3)

HO2 unconstrain HO2 constrain Y=1.35X (R2=0.76) Y=0.96X (R2=0.78)

2 4 6 8 10 12 14 16 2 4 6 8 10 12 14 16 [HO2]obs. (pptv) [HO2]model (pptv)

Y=1.89X (R2=0.67)

Modeled and observed OH and HO Modeled and observed OH and HO2

2:

: Scatterplot Scatterplot ( (Rishiri Rishiri Island, September 2003) Island, September 2003)

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Organoiodines Organoiodines (2001.6) (2001.6)

Laminaria japonica

• var. ochotensis

0-

• 0.4

0.4 0-

• 0.45

0.45 n.d n.d. . n.d n.d. . 0.1 0.1-

• 1.0

1.0 0.2 0.2-

• 1.4

1.4 Mace Head Mace Head <0.3 <0.3 0.7 0.7 <0.2 <0.2 <0.2 <0.2 0.5 0.5 1.4 1.4

night night

<0.3 <0.3 0.1 0.1 <0.2 <0.2 <0.2 <0.2 0.2 0.2 0.6 0.6 day day

• bservatory
• bservatory

(1km from coast) (1km from coast)

<0.3 <0.3 0.6 0.6 <0.2 <0.2 <0.2 <0.2 0.4 0.4 1.2 1.2

night night

<0.3 <0.3 0.1 0.1 <0.2 <0.2 <0.2 <0.2 0.3 0.3 0.9 0.9 day day coastline coastline <0.3 <0.3 0.8 0.8 0.2 0.2 0.2 0.2 1.2 1.2 2.3 2.3

night night

0.4 0.4 0.3 0.3 0.3 0.3 0.4 0.4 1.4 1.4 1.7 1.7 day day

30cm above 30cm above seaweeds seaweeds

CH CH2

2I

I2

2

CH CH2

2ICl

ICl

2 2-

• C

C3

3H

H7

7I

I 1 1-

• C

C3

3H

H7

7I

I

C C2

2H

H5

5I

I CH CH3

3I

I pptv pptv

• Dr. Yokouchi (NIES)