Role of Ammonia in Formation of Secondary Particulate Matter: A Study from Kanpur, India

Mukesh Sharma, Shyam Kishore, Tejas, and Sailesh

Environmental Engineering and Management ProgramDepartment of Civil Engineering

Indian Institute of Technology Kanpur, Kanpur 208016, India

Indoflux Meeting Chennai July 12-16, 2006

Case Study – Secondary Particle Formation

Should Air Quality Measurements be Subset of Indo-flux Measurements – if yes, how?

BACKGROUND

National Air Quality Program Suggests two Issues

o Consistently high particulate matter( PM) levelso Consistently rising levels of oxides of nitrogen (NOx)______________________________________________o Ozoneo VOCs, BTX, PAHs, Dioxins, Metalso Water Soluble Ions

0

100

200

300

400

500

600

700

SO2 NOX SPM

DELHI KOLKATA MUMBAI KANPUR

ug

/m3

Delhi

Mumbai Kolkata

Kanpur

Summer PM10 Variation

Summer NOx Variation

Time Series : 1998-2004 New Delhi

Average PM10: 400 ug/m3

d[NOx]/dt = 10 ug/m3-yr

NOx , SO2and PM10 Interlinked

Objectives of the Case - study

to understand the role of NO2, NH3, SO2, HNO3, temperature and humidity in formation of particulate sulfate and nitrate.

This is assessed in terms of:

• Inhalable PM10, NO2, HNO3, NH3

• Water soluble ion: NO3-,SO4

2-,Cl-,NH4+,Na+,K+,Ca2+ ,Mg2+ ; in PM10

Agriculture Fields

Vikash Nagar

Population ~ 3 million

Formation of Secondary Particles (Seinfeld, 1996)

NH3 (g) + HNO3 (g) ↔ NH4NO3 (s)

NaCl

NOx HNO3

NH3

SOIL

FINE MODENITRATE(NH NO )4 3

SO 2H SO2 4 (NH ) SO4 2 4

HCl

NaCl

HNO3NOx

SOIL

NH3

FINE MODENITRATE

SO 2H SO2 4 (NH ) SO4 2 4

COARSE MODE NITRATE

CaCO3 (aq) +2 HNO3 (g) → Ca (NO3)2(s) +H2O +CO2 (g)

Fine Mode

Coarse Mode

Cations, Anions, NH3 and HNO3 during Winter and Summer, 2005

0

5

10

15

20

25

30

SO4 NH4 K Ca Mg NH3 HNO3

Water Soluable Ions and NH3 and HNO3

ug

/m3

Winter

Summer

Water Soluble Ions, NH3 and HNO3

Winter: Day Night variations, 2005

0

5

10

15

20

25

30

35

40

NO3 SO4 NH4 K Na Ca Mg NH3 HNO3

Pollutant

ug

/m3

Day

Night

Water Soluble Ions, NH3 and HNO3

Summer 2005: Day-Night Variations

0

5

10

15

20

25

30

NO3 SO4 NH4 K Ca Mg NH3 HNO3

Parameter

ug

/m3

DAY

NIGHT

RECAPSummer Vs Winter

• NO3-, SO4 2-, NH4 +, K+ significantly high in winter

• Ca2+, Mg 2+, HNO3 , PM10 significantly high in summer

Winter: Day Vs Night

•NO3-, SO4 2-, NH4 +, K+, PM10, HNO3 significantly high in winter day

•Ca2+, Mg 2+, Cl -, Na +, NH3 no significant difference

Summer: Day Vs Night

• SO42-, NH4

+, K+ , significantly high in summer night

• N02 ,Ca2+, Mg2+,PM10 ,HNO3 NH3 significantly high in summer day

• NO3- , Cl- , Na+ no significant difference

Ionic balance for summer and winter

SO4

NH4

NH4

SO4

NO3

Ca

Ca

NO3

MgCl

Cl

K

K

Na

Na

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

Mg

Summer

Winter

µ equ/m3

Difference in cation and anion: 17% in winter and 24% in summer

carbonate and bicarbonate not measured and other unknown anions

Correlation Analysis

Winter SummerNO3, SO4 with NH4

Not with Ca, MgFine Mode PM Formation

SO4 with NH4

Fine Mode PM Formation

No Coarse Mode PM Formation

NO3 with Ca, Mg

Coarse Mode PM Formation

Statistical Significant Correlation (n = 17 summer; n = 18 winter)

Science…Sulfate vs Ammonium

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

Sulfate (mole/m3)

Am

mo

niu

m (

mo

le/m

3)

1:1

2:1

Comparison of NH4+ and SO4

2- ion with

stoichiomertic ratio of (NH4)2SO4.

(2:1 line reference line represents

complete SO42- neutralization).

Nitrate Vs Ammonium

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 0.2 0.4 0.6 0.8

Nitrate( mole/m3)

Am

mo

niu

m(m

ol/m3 )

1:1

Comparison of excessNH4+ and NO3

- ion

with stoichiomertic ratio of (NH4)NO3.

(The 1:1 line reference line represents

complete NO3- neutralization).

Winter Analysis

NH3 and HNO3 Equilibrium (summer)

[NH3(g)] =27.72 ppb, [HNO3(g)]=2.69 ppb and RH =41.98 %.

RH < RHD (deliquescence) , NH4 NO3 is in solid form

But…. for NH3 (g) + HNO3 (g) ↔ NH4NO3 (p)[NH3][HNO3] > K of reaction :

[NH3][HNO3] = 74.56ppb2

K( Calculated) = 306.5 ppb2

Formation of NH4NO

3 will be lower in summer

Figure 4.9Rlation between [ NH3(g)][HNO3(g)] product and temperature (summer)

1

10

100

1000

3.2 3.25 3.3 3.35 3.4 3.45 3.5 3.55Temp(1000/T,K-1)

[ N

H3(

g)][

HN

O3(

g)]

ppb2

NH3 and HNO3 Equilibrium( winter) [NH3(g)] =26.74 ppb;[HNO3(g)]=0.90ppb

RH = 85.35%; RHD (deliquescence)= 68.29%

RH > RHD, NH4NO3 is in aqueous form NH3 (g) + HNO3 (g) ↔ NH4+ + NO3-

T = 290 Kelvin, K = 3.51 ppb2

[NH3(g)] [HNO3(g)]= 24ppb2 > K

NH4NO3 Formation favored and in (aq) form

US Study (Baek and Aneja, 2004)

T= 297 Kelvin, K = 21.59 ppb2

[NH3(g)][HNO3(g)] = 32.2 ppb2> K[NH3] = 78 ppb

[HNO3] = 0.41 ppb

Nitrogen Conversion ratio

Nitrogen conversion ratio: Fn = ( PNO3

- +GNO3-)/ (NO2+ PNO3

- +GNO3- )

PNO3- particulate nitrate as NO2 ,µg/m3 ;

GNO3- gaseous nitrate concentration NO2 ,µg/m3 ;

NO2 gas phase NO2 concentration, µg/m3

Fn (summer) = 44 % GNO3 >> PNO3

Fn (winter) = 52% PNO3 >> GNO3

Science??

HNO3 and NH3 Seasonal variation

Levels of nitric acid in various seasons

P W SSeasons

1

2

3

4

5

6

7

8

Co

nce

nta

r ti o

n o

f n

i tri c

aci

d in

mic

r og

r am

/cu

.m NO2 (g) + OH. (g) → HNO3 (g) (1) O3 (g) + hν → O (1D) (g) + O2 (g) (2)O (1D) + H2O (g) → 2 OH. (g) (3)HN03 + hv → NO2 +OH. (4)HNO3 + OH →NO3 +H2O (5)

JHNO3 is the photolytic rate constant for HNO3, and depends on latitude, season and solar zenith angle. It is calculated as the product of actinic flux, quantum yield and absorption cross section area. It is corrected for every season. Concentration of [OH] depends on photolysis rate of O3.

2 3 5 3

3 1

[ ] [ ][ ]

[ ][ ]

HNONO J k HNO OH

HNO k OH M

At Equilibrium

Conclusion:HNO3 showed seasonal variation, with highest concentration in summer compared to winter and post monsoon.

Photochemical activity and shift of equilibrium from particulate phase ammonium nitrate to gas- phase ammonia and nitric acid.

The equilibrium ratio is highest in summer due to high solar radiation, which leads to higher concentration of OH radical, thereby more formation of HNO3 as determined in Table

Contd..

Species Seasonal rate constant (s-1)

PostMonsoon

Winter Summer

JHNO3 2.4× 10-7 3.1× 10-7 4.3× 10-7

k5 1.5× 10-7 1.8× 10-7 2.2× 10-7

Equilibrium ratio

Seasons

PostMonsoon

Winter Summer

Ratio 0.039 0.051 0.065

Pitts and Pitts 1986

2 3 5 3

3 1

[ ] [ ][ ]

[ ][ ]

HNONO J k HNO OH

HNO k OH M

Site NH3 Levels (ppbv) Ref.

New Delhi 47.3 ± 13.6 Kapoor et al. (1992)

Mumbai 50.7 Zuthshi et al. (1970)

Bay of Bengal 16.4 ± 3.5 Parmar et al. (2000)

Sarni 2.3 ± 0.4 Khemani et al. (1987)

Kanpur (overall) 26.3 ± 4.6 Present Study

Sampling site HNO3 NH3

PostMonsoon(µg/m3)

Summer(µg/m3)

Winter(µg/m3)

PostMonsoon(µg/m3)

Summer(µg/m3)

Winter(µg/m3)

Rampur,India - 1.3 0.3 - 2.5 8.1

Dayalbagh ,India 2.35 2.1 1.0 11.59 10.8 8.9

Cairo ,Egypt - 6.70 1.14 - - -

IITK,India - 6.90 2.39 - 18.69 19.09

Comparison… Ammonia Plays Vital Role

Where is all ammonia coming from?Global Atmospheric Sources of Ammonia

Global Atmospheric Sources of Ammonia

6%

11%

2%

5%

3%

2%

1%

28%

11%

5%

5%

11%

10%Dairy cattle

Non-dairy cattle

Buffaloes

Pigs

Poultry

Sheep/goats

Other animals

Subtotal domestic animals

Fertilisers

Agricultural crops

Biomass burning

Seas

Other sources

Sources: http://www.adsa.org/discover/intersummaries/asman.doc

India Livestock Population

World livestock population Vs India: 2003 in million nos

Animals World India % in India

Cattle 1371.1 185.181 13.506

Buffaloes 170.7 94.1 55.126

Sheep 1024 58.2 5.684

Goats 767.9 123.5 16.083

Pigs 956 17.5 1.831

Horses 55.5 0.751 1.353

Mules 12.8 0.176 1.375

Asses 40.3 0.75 1.861

Camels 19.1 0.9 4.712

Poultry NA 489 NA

Source: http://dahd.nic.in/stat.htm

India's Livestock population (%) of the World

13%

54%

6%

16%

2%

1%

1%

2%

5%

Cattle

Buffaloes

Sheep

Goats

Pigs

Horses

Mules

Asses

Camels

Winter

Post Monsoon

Summer

Flux Measurement Project – A Unique Opportunity

3 – MMulti - ObjectiveMulti – UserMulti – Parameter_______________________________________

•Act as Background AQ Stations – Time Series/Trend Analysis

•Dispersion/Deposition Studies

•Criteria Pollutants

•VOCs

•WSI – Source Apportionment, Global Warming Model, Atmospheric Chemistry

Acknowledgements….

We gratefully acknowledge

-- INDO-U.S. SCIENCE AND TECHNOLOGY FORUM -- DST, New Delhi-- Prof. Ramesh and Workshop Organizers