Spatial Distribution of Halogen Oxides in the Dead Sea Basin · Spatial Distribution of Halogen...

Universität Heidelberg Institut für Umweltphysik

Spatial Distribution of Halogen Oxides in the Dead Sea Basin

Ulrich Platt and Jutta Zingler

Institut für Umweltphysik, University of Heidelberg

Many thanks to:

The Group at HUJI

Dead Sea Works

The Massada Team

Ein Gedi Field School

Ein Gedi Kibbutz

My Students at IUP


Halogen Oxides at Salt Lakes and Salt Pans

-20-Caspian Sea (Satellite Data)

-<5-10-Lac Assal, Djibouti

-20-Salar de Uyuni, Bolivia

-615Salt Lake City, USA

10200-Dead Sea, Israel

IOBrOClOSite


Why are we interested in Halogens in the Troposphere?

Stratosphere:Ozone destruction ...

Troposphere:• Ozone destruction• Reduction of Ozone formation• Modification of the oxidation capacity (radical cycles)• Change of DMS - cycle• Particle Formation• ...


Boundary Layer Ozone Depletion - The first direct Evidencefor Reactive Halogens in the Troposphere

April 19860 5 10 15 20

Br (

ng m

-3),

O3 (

ppbv

)

0

20

40

60

80

100O3Br Barrie et al., 1988

O3, ppb

Alert 2000,Bottenheim et al., 2002

• Occur in the Arctic and Antarctic

• Are associated with halogens (especially Br)

• Probably related to events over Dead Sea and salt lakes


Halogen Catalysed Destruction of Tropospheric Ozone

1) BrO + BrO → Br + Br + O2 (rate determining) Br + O3 → BrO + O2

net: 2 O3 → 3 O2 at high BrO levels

2) BrO + HO2 → HOBr + O2 (rate determining) HOBr + hν → Br + OHOH + AO → HO2 + A (AO = O3, CO, ...)

net: 2 O3 → 3 O2 at low BrO levels

3) BrO + ClO → Br + Cl + O2 (rate determining)→ BrCl + O2→ Br + OClO + O2

net: 2 O3 → 3 O2 if ClO available

4) BrO + IO→ Br + I + O2 (rate determining)→ BrI + O2→ Br + OIO + O2

very fast, if IO available


Observation of Reactive Halogens in the Troposphere

up to 10up to 200up to 15Salt Lakes/Pans

?up to 1000several100 ppb Volcanic Plumes

?20 ... 40several10?

Polar Regions (springtime)

up to 10<2 ... 6?Coastal Regions

?1-2?Free Troposphere

IOppt

BrOppt

ClOpptDomain

Reactive halogen species: Cl, Br, I, ClO, BrO, IO, OClO,OBrO, OIO, I2O2, ...

Universität Heidelberg Institut für Umweltphysik2 Jun 3 Jun 4 Jun 5 Jun 6 Jun 7 Jun

-2

0

2

4

6

8

10

IO c

once

ntra

tion

[ppt

]

Date

2 Jun 3 Jun 4 Jun 5 Jun 6 Jun 7 Jun

-4

-2

0

2

4

6

Tide

nhöh

e [m

]

BrO-clouds in the Arctic, Jens Hollwedel et al. 2004

IO at a coastal site, Christina Peters, 2005


Simplified Outline of the XOX (=X + XO, X = I, Br, Cl) Cycles

XX

XOXO OXO

X2XNO2

XY

X2O2XONO2

HX

CH3XCHX3

etc.Na+ X-

Y -

N2O5 , etc.

heterogeneous

hν,∆

hνhν

hν

hν

hν,∆

OH, hν

RH,HO2

HO YO O3

NO2

YO

HO2

hν

HOX

(X2O2)ads(XONO2)ads (HOX)ads

(HX)ads

Sea-Salt (Snow Pack or Aerosol Surface)H+ + X-

[ ][ ] ( ) ( ) ( )XO

1000 X Cl , 100 X Br , 10 X IX

≈ = = = Daytime, rule of thumb


A Chemical Instability: The "Bromine Explosion"

Br2 + hν → 2 BrBr + O3 → BrO + O2BrO + HO2 → HOBr + O2

Salt Surface or Aerosol: HOBr + Br- + H+ → Br2 + H2O

net: BrO --> 2 BrO(Bromine – Explosion Mechanism)

InversionWell mixed Boundary Layer (up to ≈1000m)


What is the Evidence for Halogen Radicals in the Troposphere ? Indirect • „Hydrocarbon - Clock“ observations (X-atoms)

[Jobson et al. 1994, Solberg et al. 1996, Ramacher et al. 1997, 1999, Wingenter et al. 1996]

• ‘Unexplained’ loss of tropospheric Ozone [Oltmanns et al. 1986, Barrie et al. 1988, … Reichardt et al. 1996, Davies et al. 1998, ... Bottenheim et al. 2000, ...]

Semi-direct • Atomic Fluorescence after titration by NO

[Toohey et al. 1996, Avallone et al. 2002] • Chemical Amplifier (ROX-Box) Measurements

[Perner et al. 2001]

Direct • Differential Long-Path Absorption Spectroscopy (LP-DOAS)

[Hausmann & Platt 1994, Unold 1995, Tuckermann 1996, Richter et al. 1998, Wagner & Platt 1998, McElroy et al. 1999, Hebestreit et al. 1999, Alicke et al. 1999, Wittrock et al. 2000, Allan et al. 2000, 2001, Frieß et al. 2001, Matveev et al. 2001, Hönninger & Platt 2002, … ]


Joint Measurement Campaigns at the Dead Sea IUP Heidelberg – HUJI, Jerusalem

• 1997: First observation of BrO at a Salt LakeOzone destruction too fast?Br must come from the salt pans south of the Dead Sea

• 2001: 3 active LP-DOAS instruments along the Dead Sea valleyfirst observation of IOBr-source other than salt pans?

• 2002: 1 active LP-DOAS + 1 passive MAX-DOAS (Massada)Probed vertical extension of the BrO „cloud“

• 2004: 1 active LP-DOAS + (indirect)BrONO2 measurements+ 6 Mini-MAX DOAS along the Dead Sea shore

Vertical extension of IO (as well as BrO)Test of the Reservoir gas-theorySimultaneous observation of horizontal and vertical BrO distribution


Differential Optical Absorption Spectroscopy (DOAS)

turbulence

LampI0(λ)

DetectorI(λ)

trace gas absorptionabsorption cross

section σi(λ)

Rayleigh scattering~ λ-4

MieScattering~

λ-(1…3)

Lambert-Beer‘s Law:

I(λ) = I0(λ)•e- [Σσ‘i (λ)⋅ci⋅L + (σbi⋅ci + εRay(λ) + εMie(λ)) ⋅L] ⋅ T(λ))narrow- wide band extinction

Remove by high-pass filtering

• Use differences ofintensities atdifferent wavelengths

• Record the intensityin many(typ. several 100)wavelength channels(entire spectra)

• High pass-filteringof spectra⇒ remove continuum

• Fit reference spectra⇒ Make use of allspectral information


Example of a DOAS Evaluation (Fitting Procedure)A: Sample atmospheric spectrum

from April 16, 2001

B: Ozone absorption spectrum

C: BrO absorption spectrum

D: Residual (noise+unknown absorbers)

Black lines: measurementRed lines: fit result

[O3] = 6.6*1011 molec/cm³ [24 ppb][BrO] = 3.8*108 molec/cm³ [13 ppt]

300 350 400 450 500 550 600300 350 400 450 500 550 600

BrO

IO

OIO

I2

wavelength [nm]

Cro

ss S

ectio

ns [a

rb.u

nits

]


Multi-Axis DOAS the Idea

α

ϑ

z

c(z)

dzds

scattering process

trace gas profile

Sun

Va ⋅

Va ⋅− )1( Stratospheric Trace Gas Layer

Tropospheric Trace Gas Layer

Tropopause

Total Slant Column: ( )

−+⋅=+=

ϑαϑα cos11

sin1

cos1

sin1 aaVSSS StratTrop


BrO and ClO at theGreat Salt Lake

(Salt Lake City, USA)

J. Stutz UCLA

Stutz et al. 2002


Measurement Sites

Ocean conditions

On the Salt Pan

Above the Pond

The Assal Trench


Mini - MAX-DOAS Measurements of BrO at the

Salar de Uyuni (Bolivia), Oct./Nov. 2002

(N. Bobrowski, G. Hönninger)


Active LP-DOAS Measurements of BrO-at the Dead Sea, Israel, June 11, 1997

Site &light-path

salt pans& faktory

0

10

20

0255075

1000

4080

1200000 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0000

NOSWN Windrichtung

SO2 [ppb]0246

NO2 [ppb]

O3 [ppb]

Nachweisgrenze

BrO [ppt]

11 Jun 12 Jun051015Windgeschwindigkeit [m/s]

Hebestreit et al., Science 283, 55-57 1999


Netanya

Ashdod

Beer-Sheva

Jerusalem

Tel-Aviv

100 120 140 160 180 200

60

80

100

120

140

160

180

200

220

0

20

40

60

80

100

3/8/9714:00-16:00

Netanya

Ashdod

Beer-Sheva

Jerusalem

Tel-Aviv

100 120 140 160 180 200

60

80

100

120

140

160

180

200

220

20

40

60

80

100

120

31/7/9714:40-17:00

Netanya

Ashdod

Beer-Sheva

Jerusalem

Tel-Aviv

100 120 140 160 180 200

60

80

100

120

140

160

180

200

220

60

80

100

120

140

160

180

200

220

Netanya

Ashdod

Beer-Sheva

Jerusalem

Tel-Aviv

100 120 140 160 180 200

60

80

100

120

140

160

180

200

220

0

20

40

60

80

100

120

8/8/9714:00-16:20

28/8/9715:15-17:45

0 10 20 km

N

Dea

d Se

aD

e ad

Sea

Dea

d Se

aD

ead

S ea

Ozone Destruction in the Dead-Sea

Basin

Matveiv et al., JGR 106, 10375-10378, 2001


Dead Sea 2001Ein Bokek Ein Bokek

Evaporation ponds

Ovnat - 330 O3 monitors

LP-DOAS site

Ashalim - 400

North Site

Mid Site

South Site

Metzoke Dragot + 30

Ein Bokek- 410

Dead Sea Works - 400

Newe Zohar - 400

Massada + 50

Max-DOAS site Top Site

Ein Tamar - 400

-330 Heigth [m] above/ below sea level

Ein Bokek Ein Bokek

Evaporation ponds


LP-DOAS site

Ashalim - 400

North Site

Mid Site

South Site

Metzoke Dragot + 30

Ein Bokek- 410


Newe Zohar - 400

Massada + 50

Max-DOAS siteTop Site

Ein Tamar - 400


100 km100 km

• LP-DOAS at 3 sites:• Halogen Oxide, NO2 etc.• O3-monitors at 4 site• NO, SO2, CO - monitors• Weather station


Dead Sea 2001 - IO

426 427 428 429 430 431 432 433 434 435 436 437-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

Diff

eren

tial O

ptic

al D

ensi

ty [1

e-3]

Wavelength [nm]

0.99981.00001.0002

426 427 428 429 430 431 432 433 434 435 436 437

0.99981.00001.0002

00:00 02:00 04:00 06:00 08:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 24:00-2

0

2

4

6

8

10

-2

0

2

4

6

8

10M

ixin

g R

atio

5 points smoothed

IO [p

pt]

Time (UT)

20

30

40

50

60

70

8000:00 02:00 04:00 06:00 08:00 10:00 12:00 14:00 16:00 18:00 20:00 22:00 24:00

20

30

40

50

60

70

80

10 points smoothed

O

3 [pp

b]

Average diurnal variation

Zingler, J., and U. Platt (2005),Iodine oxide in the Dead SeaValley: Evidence for inorganic sources of boundary layer IO, J. Geophys. Res., 110, D07307doi.:10.1029/2004JD004993


IO at Ein Bokek (Dead Sea, Israel), 2001Zingler and Platt 2005

5.8 6.8 7.8 8.8

0

5

5.8 6.8 7.8 8.8

0

50

IO [

ppt]

GMT = Local -3 h *** 1. Tick: 0:00 UT *** Minor Tick : 3 hours

IO IOdl

BrOin ppt

O3

O3

[10

ppb]

IO up to 10ppt

No particular correlation between IO and BrO


Sources of IO at the Dead Sea

• No Macroalgae!• Microalgae (Phytoplankton): Mainly Dunaliella parva, but no

regular bloom (none since 1995).⇒ The Dead Seas is an excellent pplace to study inorganic

sources of IO.

Possible iodine source mechanisms:1) Direct surface reactions at sea water (photochemistry or

O3)(„Leaching“)2) Release from inorganic Reservoir gases (HOI, INO2, INO3,

I2, etc.)3) Release by heterogeneous reactions on salt surfaces


Dead Sea 2001: BrO – NO2 Anticorrelation

05.08.2001 06.08.2001 07.08.2001 08.08.2001

-20

0

20

40

60

80

100

-2

0

2

4

BrO

GMT = Local - 3 h *** 1. Tick: 0:00 UT *** Minor Tick: 3 hours

Date

Mix

ing

Ratio

BrO

[pp

t]

NOS

WN5 Aug 6 Aug 7 Aug 8 Aug

NOSWN

Win

d D

irIO

[ppt]

NO2

NO

2 [0

.1 p

pb]

IO


Dead Sea 2001 – BrO coming from the South?

05.08.2001 06.08.2001 07.08.2001 08.08.2001

0

25

50

75

100

125

150

0

25

50

75

100

125

150 DSW

Ein Bokek East Ovnat


Date

Mix

ing

Ratio

BrO

[pp

t]

NOS

WN5 Aug 6 Aug 7 Aug 8 Aug

NOSWN

Win

d D

ir


Ein Bokek Ein Bokek

Evaporation ponds


LP-DOAS site

Ashalim - 400

North Site

Mid Site

South Site

Metzoke Dragot + 30

Ein Bokek- 410


Newe Zohar - 400

Massada + 50

Max-DOAS site Top Site

Ein Tamar - 400


Ein Bokek Ein Bokek

Evaporation ponds


LP-DOAS site

Ashalim - 400

North Site

Mid Site

South Site

Metzoke Dragot + 30

Ein Bokek- 410


Newe Zohar - 400

Massada + 50

Max-DOAS siteTop Site

Ein Tamar - 400


MassadaMassada

100 km100 km

EastEast WestWest

Dead Sea 2002

MAXMAX--DOAS, DOAS, OO33, , MeteorologyMeteorology


Massada 2002


BrO Slant Column Density Profile

25.6 26.6 27.6 28.6 29.6 30.6 1.7

-2x1014

0

2x1014

4x1014

6x1014

8x1014

25.6 26.6 27.6 28.6 29.6 30.6 1.7

-2x1014

0

2x1014

4x1014

6x1014

8x1014

-45° -10° - 5° - 2° 0° 2° 5° 10° 90°

BrO

-dS

CD

[mol

ec/c

m2 ]

Time [UT = LT-3h]


… Understanding the Results!

Dead Sea Basin „filled“ with BrO


MAX-DOAS at Massada

Elevation angles to scale


MAX-DOAS at Massada 2002: BrO-O3 Anticorrelation

21.6 22.6 23.6 24.6 25.6 26.6 27.6 28.6 29.6 30.6 1.7

-2x1014

0

2x1014

4x1014

6x1014

8x1014

21.6 22.6 23.6 24.6 25.6 26.6 27.6 28.6 29.6 30.6 1.7

-30

-20

-10

0

10

20

30

40

50

60

70

80

90 -45° -10° - 5° - 2° 0° 2° 5° 10° 90°

BrO

-dS

CD

[mol

ec/c

m2 ]

Time [UT = LT-3h]

O3

Ozone [ppb]


Ein Bokek Ein Bokek

Evaporation ponds

Ovnat - 330 Monitors

LP-DOAS site

Ashalim - 400

Metzoke Dragot + 30

Ein Bokek- 410


Newe Zohar - 400

Massada + 50

Max-DOAS site

Ein Tamar - 400


Ein Gedi- 300

Ein Bokek Ein Bokek

Evaporation ponds

Ovnat - 330 Monitors

LP-DOAS site

Ashalim - 400

Metzoke Dragot + 30

Ein Bokek- 410


Newe Zohar - 400

Massada + 50

Max-DOAS site

Ein Tamar - 400


Ein Gedi- 300

Dead Sea 2004

6 Mini6 Mini--MAX MAX DOAS DOAS Instruments Instruments along the Dead along the Dead Sea shoreSea shore


Dead Sea 2004 – IO MAX-DOAS

04 05 06 07 08 09 10 11 12 13 14 15 160.00E+000

1.00E+013

2.00E+013

3.00E+013

4.00E+013

5.00E+013

6.00E+013

7.00E+013

8.00E+013

21.06.2004 G746

Elevation AngledS

CD

IO [m

olec

/cm

²]

Time [UT = Local Time - 3 h]

0

1.000

2.000

3.000

4.500

6.000

10.00

20.00

20.00

415 420 425 430 435 4400.9985

0.9990

0.9995

1.0000

1.0005

1.0010

File #3281 - 21.06.04 11:25UT Elev 2°

Fit Fit + ResiduumO

ptic

al d

ensi

ty IO

W avelength [nm]


MAX-DOAs BrO, Ein Gedi Kibbuz 2004 Parallell to LP-DOAS (and coast)

03:0004:00 05:0006:0007:00 08:0009:0010:0011:00 12:0013:0014:00 15:0016:00-1,00E+014

0,00E+000

1,00E+014

2,00E+014

3,00E+014

4,00E+014

5,00E+014

6,00E+014

7,00E+014

8,00E+014

9,00E+014

1,00E+015

1,10E+015

22.06.2004 G740

Elevation Angle

dSC

D B

rO [m

olec

/cm

²]


-1,000

0

1,000

2,000

3,000

4,500

6,000

10,00

20,00

20,00


MAX-DOAs BrO, Ein Gedi Kibbuz 2004 Orthogonal to LP-DOAS (and coast)

03:0004:00 05:0006:0007:00 08:0009:0010:0011:00 12:0013:0014:00 15:0016:00-3,00E+014

-2,00E+014

-1,00E+014

0,00E+000

1,00E+014

2,00E+014

3,00E+014

4,00E+014

5,00E+014

6,00E+014

7,00E+014

8,00E+014

22.06.2004 G745

Elevation Angle

dSC

D B

rO [m

olec

/cm

²]


0

1,000

2,000

3,000

4,500

6,000

10,00

20,00

20,00


BrONO2 = NO2(Monitor) – NO2(DOAS) ?

16.6 17.6 18.6 19.6 20.60

3

6

916.6 17.6 18.6 19.6 20.6

0

1

2

3 NO2 Monitor

NO

2 [pp

b]

Time [UT *** 1 minor tick = 4 hours]

NO

[ppb]

NO Monitor NO2 DOAS

?


What we learned ...• Large amounts of reactive Br is released by salt pans or

(possible) salt sea surfaces.• At the Dead Sea IO is likely to be released by inorganic

processes (elsewhere it appears to be released by biological precursors).

• Vertical distribution of halogen oxides.

Open questions ...• Abundance of reactive Cl?• Release mechanism(s)• Release from salt pans, aerosol, or also from sea surface?• Importance on global scale?• Particle formation?• Mercury?


The End


BrONO2 = NO2(Monitor) – NO2(DOAS) ?

16.6 17.6 18.6 19.6 20.60

3

6

916.6 17.6 18.6 19.6 20.6

0

30

60

90

NO2 Monitor

NO

2 [ppb

]

Time [UT *** 1 minor tick = 4 hours]

NO2 DOAS

BrO [ppt]

3. Lichtweg 3. Lichtweg ––Nicht benutztNicht benutzt

0.5 km0.5 km

Active LP-DOAS measurements at Ein Bokek2001

•Sonic Anemometer•LP-DOAS mit 2 Light Paths:

–East: 8477 m–Mountain 1966 m


IO at Lilia, Brittany, France, Atlantic Coast 06.5.2003 - 13.6.2003, C. Peters et al.

2 Jun 3 Jun 4 Jun 5 Jun 6 Jun 7 Jun-2

0

2

4

6

8

10

IO c

once

ntra

tion

[ppt

]

Date

2 Jun 3 Jun 4 Jun 5 Jun 6 Jun 7 Jun

-4

-2

0

2

4

6

Tide

nhöh

e [m

]


Multi-Axis DOAS (MAX-DOAS) for Detection of Plumesfrom Urban Areas, Stacks, Volcanoes, Biomass Burning:

Static Scanning Instruments

B

A

Viewing geometries using static scanning MAX-DOAS instruments.

In a combination of two or more systems (A, B) the vertical distribution of the plume can be determined by triangulation.


MAX - DOAS BrO from Soufriere Hills Volcano on Montserrat, Caribean, May 25, 2002

BrO

Optical D

ensity [%]B

rO S

CD

[mol

ec/c

m2 ]

elevation angle [°]330 340 350 360

330 340 350 360

-4

-3

-2

-1

0

1

2

3

4

511

0 10 20 30 40 50 60 70 80 90

0.0

2.0x1014

4.0x1014

6.0x1014

8.0x1014

1.0x1015

1.2x1015

1.4x1015

0 10 20 30 40 50 60 70 80 90

1098765

1

2

3

4

109

5

7

8

2

3

4

6

1

α α1

α2

hp

d≈1kmLL

View from west

β

σ

x

Bobrowski et al., Nature 423, 15 May, 273-276, 2003.


BrO : SO2 ≈ 1 : 1000 (Molar Ratio)

Global SO2Emission fromVolcanoes:

≈ 14 Mio. t/year

assuming sameBr:S ratio as Monserrat for all Volcanoes:

→ 30 000 t Br/year

possibly up to 150 Kt Br/year


Vertical Resolution of MAX-DOAS --> ‘Poor Man’s LIDAR’∆SCD’s Measured on May 4, 2000 (15:15 UT – 15:40 UT), Alert 2000 PSE

0.0

0.5

1.0

1.5

2.0

2.5

0.0 0.1 0.2 0.3 0.4 0.5

0.0

0.5

1.0

1.5

2.0

2.5

25102090

α -1 [deg-1]

elevation angle α [°]

∆SC

D B

rO [1

014cm

-2]

measuredmodelled

P1 (0-1km) P2 (0-2km) P3 (0-1km+1-2km) P4 (1-2km) P5 (O4) P6 (strat.)

Hönninger and Platt, 2000


Campaign 5 (Juni -Juli 2002), Multi-Axis (MAX)-DOAS at MassadaJ. Zingler

Arad

Jordain

Massada

Dead Sea

BrO-Plume

600 m

460 m

30 km10 km

Elevationangle

Straylight


25.06.2002 26.06.2002 27.06.2002 28.06.2002 29.06.2002 30.06.2002 01.07.20020.0

0.5

1.0

1.5

2.0

2.525.6 26.6 27.6 28.6 29.6 30.6 1.7

0.0

0.5

1.0

1.5

2.0

2.5

-45° horizontal -10° +02° -05° +5° -02° +10°

BrO

-dSC

D [

arb.

uni

ts]


MAX-DOAS BrO-Vertical Profile - Measurements, 2002


Conclusions

• Reactive Bromine species (e.g. BrO) are found in the polar boundary layer during spring, at salt lakes, and in volcanic emissions

• BrO could have a profound effect on tropospheric ozone

• Reactive Iodine (IO, OIO) species are found in practicallyall coastal areas, BrO was found in one case.

• Source mechanisms of reactive halogen species in the troposphere are not well understood

Date post:	11-Apr-2019
Category:	Documents
Upload:	hoangduong
View:	214 times
Download:	0 times

Spatial Distribution of Halogen Oxides in the Dead Sea Basin · Spatial Distribution of Halogen...

Documents