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Fossil and modern sources of aerosol carbon in the Netherlands – A year-long radiocarbon study . U. Dusek 1 , M. Monaco 1 , A. Kappetijn 1 , T . Röckmann 1 S . Szidat 2 , H . A. J. Meijer 3 , J. van der Plicht 3 ,

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Fossil and modern sources of aerosol carbon in the Netherlands –

A year-long radiocarbon study

U. Dusek1, M. Monaco1, A. Kappetijn1, T. Röckmann1

S. Szidat2, H. A. J. Meijer3, J. van der Plicht3,

1 Institute for Marine and Atmospheric research Utrecht (IMAU), the Netherlands

2 Center for Isotope Research, Groningen University, the Netherlands

3 Laboratory for Radiochemistry and Environmental Chemistry, University of Bern, Switzerland


Radiocarbon Netherlands –

Carbon isotopes:

C12 : 98.89 %

C13: 1.11 %

C14: 0.0000000001%

Half life: 5730 yrs

Produced by

cosmic rays

Unit of measurement:

Fraction modern

fm = 14C sample/14C standard

Standard: oxalic acid (typical activity of 1950 biosphere)

fm > 1 possible through bomb tests

Exchange with

Biosphere as

14CO2

Decay when

Exchange with

Biosphere stops


Carbonaceous aerosol: Netherlands – 14C for source apportionment

fm = 1.1 - 1.2

fm = 0

fm ~ 1.04

Biomass burning

Biogenic

Fossil fuel

EC

OC

Thermally refractory

Volatile - refractory


From aerosol particles to Netherlands – 14C measurement

Sampling:

Goal: 50 – 500 ugC

High volume samplers:

500 l/min of air through filter

Convert OC and EC to CO2

Measure 14C content with AMS


Combustion in pure oxygen Netherlands –

TC

15 min at 650 C

2 min at

450 C

15 min

at 360 C

15 min at 650 C

WIOC

Carbonaceous aerosol

Water

extraction

RC

15 min at 360 C

Pump away

OC


Time series Netherlands –

Marine

Very dry

spring

Continental

Very dry

Fall

Mixed

Very rainy

Cold summer


Time series Netherlands –

Marine

Continental

Mixed


Seasonal variation Netherlands –

fm: WSOC > OC > TC > WIOC > EC

Least seasonal variation in WSOC

Most in EC

Highest fm in spring


Contribution of biomass burning to EC Netherlands –

Detection level of our method?

Why so high in spring?

Possible biological influence?

Fires in the spring


Dependence of Netherlands – fm on carbon concentration

Pollution events

Low concentrations of TC: low fm

Very high concentrations of TC: low fm

At moderate TC concentrations 1- 5 ug/m3:

variations in TC concentration caused by modern source


Correlation of Netherlands – fm WIOC and EC

fm(WIOC), fm(EC) correlated

Common modern source

Extra biogenic background source for WIOC


Day-night variations Netherlands –

Higher fm during night:

Higher traffic emissions during day

Condensation of semi-volatile biogenic organic during night


Conclusions Netherlands –

  • Possible components other than EC in refractory material:

    • Pollen, other biological things?

    • fM(TC) lowest in summer, highest in spring

  • Overall high values of fM(TC) and fM(OC)

  • Pollution events with clear low fM signature

  • fM(EC) high in continental air masses, except in summer

  • Negligible biomass burning contribution in summer

  • Distinct day-night variation with lower fM during day


Acknowledgements Netherlands –

Thanks to

B. Oyama

for assistance with sampling and filter preparation

This study was funded by the Dutch NWO grant number 820.01.001


Contamination: Analysis of standards with known Netherlands – 14C content

Comparison with typical sample size and handling blank values


Time series Netherlands –


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