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
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. Dusek 1,
M. Monaco 1, A. Kappetijn 1, T. Rckmann 1 S. Szidat 2, H. A. J.
Meijer 3, J. van der Plicht 3, 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 U. Dusek 1, M. Monaco 1, A.
Kappetijn 1, T. Rckmann 1 S. Szidat 2, H. A. J. Meijer 3, J. van
der Plicht 3, 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
Slide 2
Radiocarbon Carbon isotopes: C 12 : 98.89 % C 13 : 1.11 % C 14
: 0.0000000001% Half life: 5730 yrs Carbon isotopes: C 12 : 98.89 %
C 13 : 1.11 % C 14 : 0.0000000001% Half life: 5730 yrs Produced by
cosmic rays Exchange with Biosphere as 14 CO 2 Decay when Exchange
with Biosphere stops Unit of measurement: Fraction modern f m = 14
C sample / 14 C standard Standard: oxalic acid ( typical activity
of 1950 biosphere ) f m > 1 possible through bomb tests Unit of
measurement: Fraction modern f m = 14 C sample / 14 C standard
Standard: oxalic acid ( typical activity of 1950 biosphere ) f m
> 1 possible through bomb tests
Slide 3
Carbonaceous aerosol: 14 C for source apportionment Biomass
burning Fossil fuel Biogenic ECOC f m = 1.1 - 1.2f m = 0f m ~ 1.04
Thermally refractoryVolatile - refractory
Slide 4
From aerosol particles to 14 C measurement Sampling: Goal: 50
500 ug C High volume samplers: 500 l/min of air through filter
Sampling: Goal: 50 500 ug C High volume samplers: 500 l/min of air
through filter Convert OC and EC to CO 2 Measure 14 C content with
AMS
Slide 5
Combustion in pure oxygen Carbonaceous aerosol 15 min at 650 C
TC 15 min at 360 C OC Water extraction 15 min at 360 C WIOC 15 min
at 650 C RC 2 min at 450 C Pump away
Slide 6
Time series Very dry spring Very rainy Cold summer Very dry
Fall Marine Continental Mixed
Slide 7
Time series Marine Continental Mixed
Slide 8
Seasonal variation fm: WSOC > OC > TC > WIOC > EC
Least seasonal variation in WSOC Most in EC Highest fm in
spring
Slide 9
Contribution of biomass burning to EC Detection level of our
method? Why so high in spring? Possible biological influence? Fires
in the spring
Slide 10
Dependence of fm on carbon concentration 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 Pollution events
Slide 11
Correlation of f m WIOC and EC f m (WIOC), f m (EC) correlated
Common modern source Extra biogenic background source for WIOC
Slide 12
Day-night variations Higher fm during night: Higher traffic
emissions during day Condensation of semi-volatile biogenic organic
during night
Slide 13
Conclusions Possible components other than EC in refractory
material: Pollen, other biological things? f M (TC) lowest in
summer, highest in spring Overall high values of f M (TC) and f M
(OC) Pollution events with clear low f M signature f M (EC) high in
continental air masses, except in summer Negligible biomass burning
contribution in summer Distinct day-night variation with lower f M
during day
Slide 14
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
Slide 15
Contamination: Analysis of standards with known 14 C content
Comparison with typical sample size and handling blank values