P. D. Hien, V. T. Bac, N. T. H. ThinhVietnam Atomic Energy Commission

24h_PM10 Lang-Hanoi

0

150

300

450

Jul-98

Dec-98

May-99

Nov-99

Apr-00

Sep-00

Feb-01

Aug-01

Jan-02

Jun-02

Nov-02

May-03

Oct-03

Mar-04

Aug-04

ug

m-3

24h_PM2.2 Lang-Hanoi

0

100

200

Jul-98

Dec-98

May-99

Nov-99

Apr-00

Sep-00

Feb-01

Aug-01

Jan-02

Jun-02

Nov-02

May-03

Oct-03

Mar-04

Aug-04

ug

m-3

Observations & Approach

• Mean PM10 = 89 gm-3, mean PM2.2 = 37 gm-3

• 24-h PM10 > 150 gm-3 on 70-80 days/year,

• Preliminary source characterization showed mineral dust and long-range transport sulfate are dominant in the coarse and fine fraction,

• Comparative study on urban and rural pollution would provide significant information on properties and sources of coarse and fine PM10,

• For that purpose, coarse and fine PM10 samples were analyzed for elements (Al, Ca, Cl, Fe, K, Mg, Mn, Pb, Si, Ti, V, Zn) by PIXE and water soluble ions (Ca2+, Mg2+, K+, Na+, NH4

+, Cl-, SO42-, NO3

-) by

IC Dionex 600

Hanoi Lucnam

Hanoi-to-Lucnam concentration ratios

urban/rural ratio

0

1

2

3

4

5

NH4 V Mg

Na+ K Cl

Cl- Si

Al Ti

SO4

K+

Mg+ Fe

NO3

Mn

Mass

Pb

Ca

Ca+ Zn

fine coarse

Urban vs. rural PM10

  Coarse mass is 2 times higher in urban But, fine mass is similar, about 31 gm-3

Fine SO4, K, K+, BC are similar

Ca2+ (construction), Pb and Zn (vehicle) are from 3-5 times more abundant in urban,

  NH4+ more abundant in rural,

Similar sources of PM10 at two sites

• Coarse: Soil-nitrate, soil-sulphate, distant and local coal fly ash, sea salt, ammonium sulphate,

• Fine: Long-range transport, soil dust, distant and local coal fly ash, Cl-depleted marine aerosols, biomass burning,

But• Vehicle derived dust (coarse and fine)

found only at the urban site.

050100150200

Al

Ca

Ca++ Cl

Cl-Fe K K+

Mg

Mg++

Mn

Na+

NH4+

NO3- Pb Si

SO4- TiV Zn

soil-nitrate Lucnam

0

200

400

600

Al

Ca

Ca++ Cl

Cl-Fe K K+

Mg

Mg++

Mn

Na+

NH4+

NO3- Pb Si

SO4- TiV Zn

soil-sulphate

0200400600800

Al

Ca

Ca++ Cl

Cl-Fe K K+

Mg

Mg++

Mn

Na+

NH4+

NO3- Pb Si

SO4- TiV Zn

distant coal

0

200

400

Al

Ca

Ca++ Cl

Cl-Fe K K+

Mg

Mg++

Mn

Na+

NH4+

NO3- Pb Si

SO4- TiV Zn

local coal

0100200300400

Al

Ca

Ca++ Cl

Cl-Fe K K+

Mg

Mg++

Mn

Na+

NH4+

NO3- Pb Si

SO4- TiV Zn

soil-nitrate Hanoi

0200400600800

Al

Ca

Ca++ Cl

Cl-Fe K K+

Mg

Mg++

Mn

Na+

NH4+

NO3- Pb Si

SO4- TiV Zn

soil-sulphate

0

100

200

300

Al

Ca

Ca++ Cl

Cl-Fe K K+

Mg

Mg++

Mn

Na+

NH4+

NO3- Pb Si

SO4- TiV Zn

distant coal

0200400600800

Al

Ca

Ca++ Cl

Cl-Fe K K+

Mg

Mg++

Mn

Na+

NH4+

NO3- Pb Si

SO4- TiV Zn

local coal

soil-sulphate

31%

soil-nitrate

20%

amm. sulphate

13%

marine12%

road dust8%

local coal8%

distant coal8%

Hanoi, coarse

Lucnam, coarse

soil-sulphate

31.1%

distant coal

22.4%

local coal

13.6%

soil-nitrate9.5%

marine9.3%

ammon. sulphate

14.2%

Findings (coarse)

• Soil-derived dust 3 times more abundant at urban site, • But coal fly ash is little more abundant at rural site,• Common distant coal burning sources affects both sites • Mineral dust (MD) provides sites for nitrate and sulfate

formation by reactions with nitrogen and sulfur gases.• Nitrate bound mainly to Ca-richest soil dust,• Sulfate formed on soil dust (with higher Ca/Si ratio) rather

than coal fly ash,• Coarse ammonium sulfate found on soil organic matter

fraction

LRT Lucnam

0100020003000

BC Al

Ca

Ca++ Cl

Cl-Fe KK+

Mg

Mg++

Mn

Na+

NH4Pb Si

SO4- Ti V

Zn

LRT Hanoi

01000200030004000

BC Al

Ca

Ca++ Cl

Cl-Fe KK+

Mg

Mg++

Mn

Na+

NH4Pb Si

SO4- Ti V

Zn

Cl-depl. marine

0200400600

BC Al

Ca

Ca++ Cl

Cl-Fe KK+

Mg

Mg++

Mn

Na+

NH4Pb Si

SO4- Ti V

Zn

Cl-depl. marine

0200400600

BC Al

Ca

Ca++ Cl

Cl-Fe KK+

Mg

Mg++

Mn

Na+

NH4Pb Si

SO4- Ti V

Zn

soil

0

200

400

BC Al

Ca

Ca++ Cl

Cl-Fe KK+

Mg

Mg++

Mn

Na+

NH4Pb Si

SO4- Ti V

Zn

soil

0

100

200

BC Al

Ca

Ca++ Cl

Cl-Fe KK+

Mg

Mg++

Mn

Na+

NH4Pb Si

SO4- Ti V

Zn

biomass

0300600900

BC Al

Ca

Ca++ Cl

Cl-Fe KK+

Mg

Mg++

Mn

Na+

NH4Pb Si

SO4- Ti V

Zn

biomass

0

200

400BC Al

Ca

Ca++ Cl

Cl-Fe KK+

Mg

Mg++

Mn

Na+

NH4Pb Si

SO4- Ti V

Zn

Lucnam, FM=32 ugm-3

biomass11%

distant coal11%

Cl-depleted

7%

soil dust5%

long-range

transport36%

local coal26%

ammoni. sulphate

4%

long-range transport

36%

local coal11%

soil dust10%

Cl-depleted

10%

vehicle8%

biomass6%

distant coal 19%

Hanoi, fine PM10, FM=31.1 ugm-3

Findings (fine)

• The loadings of LRT aerosols are similar (~11 gm-3) and largest at both sites – Trans-boundary pollution.

• LRT aerosols are soot particles (containing EC and K) incorporating SO4 & NH4 during atmospheric transport of air masses,

• Coal fly ash – largest source at rural and second largest source at Hanoi site,

• Vehicles contribute 3 times less than coal burning at Hanoi and insignificant at rural areas.

• Biomass burning: 2 times weaker in Hanoi.

Summary

Implications on AQ management

 It is a mistake that air quality in rural areas is not “a matter of concern”. In fact, PM2.5 is not less abundant in rural than urban areas,

 Coal fly ash and soil dust are major components of PM10

in northern Vietnam that should be adequately addressed to improve air quality,

• Toxic nitrogen and sulfur gases are absorbed on soil and soot particles and transformed into nitrate and sulfate,

• LRT accounts for ~20% of PM10 mass in both rural and urban areas indicating the importance of transboundary pollition in the region.