Analysis of Atmospheric Mercury Speciation at HEDO Station, Okinawa

Eric Prestbo Ph.D. ([email protected])

Analysis of Atmospheric Mercury Speciation at HEDO Station, Okinawa


Shanghai

Hong Kong

Beijing


Anthropogenic Sources of Hg in 1995Pacyna et al.- 2003 LRT Workshop

Hg0 – Ton/yr

Hg(II) – Ton/yr

PHg – Ton/yr


Atmospheric Mercury Nomenclature

• Hg0 or GEM - Gaseous Elemental Mercury

• PHg – Particulate Bound Hg (2.5 um)

• RGM - Reactive Gaseous Mercury - HgCl2?


Instrument Description: Atmospheric Mercury Speciation


HEDO Mercury

0

1

2

3

4

5

84 88 92 96 100 104 108 112 116 120

Julian Day

Ele

me

nta

l Hg

(n

g/m

3)

0

10

20

30

40

50

PH

g a

nd

RG

M (

pg

/m3

)

Hg0 PHg RGM


Measurement vs Model

Hedo Mean Hg0 = 2.04 ng/m3

Hedo Max Hg0 = 5.47 ng/m3

Seignuer et al., 2004 ES&T 38:555


Measurement vs Model

Dastoor and Larocque., 2004 Atmos. Env. 38:147

Hedo Mean Hg0 = 2.04 ng/m3

Hedo Max Hg0 = 5.47 ng/m3


Measurement vs ModelHedo RGM Mean = 4.51 pg/m3

Hedo RGM Max = 32.5 pg/ m3



Measurement vs ModelHedo PHg Mean = 3.05 pg/m3

Hedo PHg Max = 16.5 pg/ m3



Comparison of Model and Observation of Hg0 Seignuer et al., 2004 ES&T 38:555

Location Date Model (ng/m3)

Obs

W. Korea Spring 2001

3.72 2.13

Seoul, Korea Sept-97 May-98

3.43-3.94 2.03; 2.12

Kyushu, Japan 1996 10.8 1.70

Beijing, China Jan, Feb, Sept 98

6.2 – 24.7 2.26; 2.38

HEDO, Okinawa Spr-2004 1.7-1.9 2.04

Changchun, China

**PHg**

Jul-Jan 2000

0.02-2 (PHg) 0.06 - 2


0

1

2

3

4

5

6

80 85 90 95 100 105 110 115 120 125

Julian Day

Hg

0 (

ng

/m3 )

and

1-u

m S

O4 (

ug

/m3 x

10)

0

100

200

300

400

500

600

CO

(p

pb

)

Hg0 CO

Beijing - China


0

1

2

3

4

5

6

80 85 90 95 100 105 110 115 120 125

Julian Day

Hg

0 (

ng

/m3 )

and

1-u

m S

O4 (

ug

/m3 x

10)

0

100

200

300

400

500

600

CO

(p

pb

)

Hg0 CO


0

1

2

3

4

5

6

80 85 90 95 100 105 110 115 120 125

Julian Day

Hg

0 (

ng

/m3 )

and

1-u

m S

O4 (

ug

/m3 x

10)

0

100

200

300

400

500

600

CO

(p

pb

)

Hg0 CO

LOCAL?


0

1

2

3

4

5

6

80 85 90 95 100 105 110 115 120 125

Julian Day

Hg

0 (

ng

/m3 )

and

1-u

m S

O4 (

ug

/m3 x

10)

0

100

200

300

400

500

600

CO

(p

pb

)

Hg0 CO


High Hg0 and CO often begins with rainfall note also SO4 washout

HEDO Hg0, CO, 1-um SO4 and Rainfall

0

1

2

3

4

5

80 85 90 95 100 105 110 115 120 125Julian Day

Hg

0 (

ng

/m3)

an

d R

ain

(m

m)

0

100

200

300

400

500

CO

(p

pb

) an

d 1

-um

SO

4

x10

(ug

/m3 )

Hg0 Rain (mm) CO 1-um SO4


Evidence for Biomass Signal?Organic Rich – Sulfate Low

0

1

2

3

4

5

6

89 90 91 92 93 94 95Julian Day

Hg

0 (n

g/m

3 ) a

nd

1-u

m O

rg (

ug

/m3 )

0

100

200

300

400

500

600

CO

(p

pb

) a

nd

1-u

m S

O4

(u

g/m

3 x

10

)

Hg0 1-um Organic CO 1-um SO4


Evidence for Biomass Signal?Organic Rich – Sulfate Low

0

1

2

3

4

5

6

83 84 85 86 87 88 89Julian Day

Hg

0 (n

g/m

3) a

nd

1-u

m O

rg (

ug

/m3)

0

100

200

300

400

500

600

CO

(p

pb

) an

d 1

-um

SO

4 (u

g/m

3 x1

0)

Hg0 1-um Organic CO 1-um SO4


NAAPS Forecast

Smoke

SO4


No clear observation of a dust event

0

1

2

3

4

5

6

80 85 90 95 100 105 110 115 120 125Julian Day

Hg

0 (n

g/m

3 )

0

100

200

300

400

500

600

CO

(p

pb

), S

cat

(m-1

x 1

06)

an

d

SO

4 (u

g/m

3 x1

0)

Hg0 CO 1-um SO4 Neph


NAAPS Forecast – over predicts

Dust

SO4


PHg correlates well with SO4 and CO

0

5

10

15

20

25

30

85 89 93 97 101 105 109 113 117 121

Julian Day

PH

g (

pg

/m3

) a

nd

1-u

m S

04

(u

g/m

3)

0

100

200

300

400

500

600

CO

(pp

b)

1-um SO4 PHg CO


RGM Does not correlate well with CO or SO4 - Why?

y = 1.4278x + 208.91R2 = 0.0133

0

100

200

300

400

500

600

700

800

0 5 10 15 20 25 30 35

RGM (pg/m3)

CO

(p

pb

)


Low-Level RGM and PHg Emissions results

in faster local removal by Dry Deposition?

< 50 Meter Total Hg Emissions (tons/yr)

>150 Meter Total Hg Emissions (tons/yr)

Pacyna et al.- 2003 LRT Workshop


Why are RGM values lower than models and uncorrelated with pollution

compounds?

Hypothesis – RGM from anthropogenic emissions are preferentially reduced to Hg0 via the complex chemistry of S02 > S03 > S04 during cloud droplet formation and evaporation


What controls [RGM] – Photochemistry?

HEDO - Hg Species Diurnal Pattern

1.6

1.8

2.0

2.2

2.4

0:00

-2:0

0

3:00

-5:0

0

6:00

-8:0

0

9:00

-11:

00

12:0

0-14

:00

15:0

0-17

:00

18:0

0-20

:00

21:0

0-23

:00

Local Time of Day (JST)

Hg

0 (n

g/m

3)

1

3

5

7

9

RG

M a

nd

PH

g (

pg

/m3)

GEM

PHg

RGM


RGM and Solar Insolation

0

10

20

30

40

103 104 105 106 107 108 109 110 111 112 113

Julian Date

[RG

M]

(pg

/m3 )

0

1000

2000

3000

4000

So

lar

Inso

lati

on

(w

atts

/m2 )

RGMSolar Flux

0

1

2

3

4

103 104 105 106 107 108 109 110 111 112 113Julian Day

Hg

0 (

ng

/m3)

0

100

200

300

400

CO

(p

pb

)

Hg0 CO

Hg0


Future Data Interpretation

• More refined analysis of each event with respect to AMS and meteorology

• Support hypothesis that SO3 is preferentially converting emitted Hg(II) to Hg0 during cloud water processing (formation/evaporation)

• Rule out local impacts


Future: Need Hg Deposition Data!

• Inventories coupled to models predict high deposition in NW Pacific due to RGM and PHg emissions

• Measurements needed to confirm at HEDO and elsewhere

• Should be event based – at least for intensive study periods

• What Hg deposition data is currently being collected or published?


Continuous Mercury Speciation at HEDO

• Depending on support-level we can do complete Automated Hg speciation system – or only total gaseous Hg with select intensive studies

Analysis of Atmospheric Mercury Speciation at HEDO Station, Okinawa

Documents

Transcript of Analysis of Atmospheric Mercury Speciation at HEDO Station, Okinawa