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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

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Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

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


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

Radiocarbon

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


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

Carbonaceous aerosol: 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


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

From aerosol particles to 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


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

Combustion in pure oxygen

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


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

Time series

Marine

Very dry

spring

Continental

Very dry

Fall

Mixed

Very rainy

Cold summer


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

Time series

Marine

Continental

Mixed


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

Seasonal variation

fm: WSOC > OC > TC > WIOC > EC

Least seasonal variation in WSOC

Most in EC

Highest fm in spring


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

Contribution of biomass burning to EC

Detection level of our method?

Why so high in spring?

Possible biological influence?

Fires in the spring


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

Dependence of 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


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

Correlation of fm WIOC and EC

fm(WIOC), fm(EC) correlated

Common modern source

Extra biogenic background source for WIOC


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

Day-night variations

Higher fm during night:

Higher traffic emissions during day

Condensation of semi-volatile biogenic organic during night


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

Conclusions

  • 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


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

Acknowledgements

Thanks to

B. Oyama

for assistance with sampling and filter preparation

This study was funded by the Dutch NWO grant number 820.01.001


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

Contamination: Analysis of standards with known 14C content

Comparison with typical sample size and handling blank values


Fossil and modern sources of aerosol carbon in the netherlands a year long radiocarbon study

Time series


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