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Air CO2 extraction and measurement
Air sampler is fabricated
following a design
developed by CSIRO
(Francey et al., 1996),
(Guha and Ghosh,
2012, under review)
Collection of air samples During 2008 -2009 Evacuation method During 2009 -2011 Flush fill method using air sampler
Extraction of CO2 from the air samples collected
During 2008 -2009 Glass extraction line During 2009 -2011 Stainless steel extraction line
designed following a
prototype at MPI
(Werner et al.,
2003),(Guha and
Ghosh, 2012, under
review)
Lower value refers to depletion- indicating
contribution from more fossil fuel combusted
CO2
Working gas is first scaled to VPDB using NBS19 and MARJ1 (used as primary standards) and
finally the air samples are represented in VPDB scale
Measurement of isotopic ratios of the extracted CO2 using isotope ratio mass
spectrometer (IRMS MAT253)
44, 45 , 46, 47, 48 & 49 masses of the extracted CO2 is measured in the dual inlet peripheral against the working
gas CO2. to get the d13C of CO2 which is further corrected for N2O contribution (Guha and Ghosh, 2012, under
review)
Calibration of experimental set up with international air standard JRAS air
reference material: Set of JRAS reference material (JRAS MAR-J1 and JRAS OMC-J1) comes with assigned value, we have
measured them again using our set up, the difference between these two measurements define the offset of our set
up from international scale which is corrected latter for all the samples to represent them in internationally accepted
scale for air CO2 measurement
Precision of measurement of both mixing ratio and d13C of CO2 :
During 2008 -2009 evacuation method in glass extraction line –------------------ ±9.3mmol.mol-1 & ±0.09‰
During 2009 end evacuation method in stainless steel extraction line –------------- ±7.6mmol.mol-1 & ±0.09‰
During 2009 -2011 evacuation method in stainless steel extraction line –------------- 7mmol.mol-1 & 0.05‰
Guha and Ghosh, 2012, under review
Steady rise in
CO2
concentration
leads to global
warming
Atmospheric CO2
monitoring stations
throughout the
world
Bangalore-
urban station
in India for
monitoring of
atmospheric
CO2
Diurnal variation: higher mixing ratio
with depleted d13C of air CO2 in the
morning compared to afternoon Identification of isotopic ratio of the
source CO2 for the diurnal variation
using Keeling approach based on
inverse relation between mixing ratio
and d13C of air CO2
Location of our sampling station
Indian Monsoon controlling the effect of anthropogenic emission on the seasonal variation of air-CO2 over Bangalore, India
Tania Guha1* & Prosenjit Ghosh1#
1Centre for Earth Sciences, Indian Institute of Science, Bangalore -560012, India
*presenting author: [email protected]; [email protected] # [email protected]
Identification of isotopic ratio of
the source CO2 for the seasonal
scale variation using Keeling
approach based on inverse
relation between mixing ratio and
d13C of air CO2
Diurnal variation: average d13C value
of source CO2 is found to be -25‰
indicating fossil fuel, biomass burning
or car exhaust as major sources of
CO2
Seasonal
variation:
average d13C
value of source
CO2 is found to
be -14.6‰
Three years (2008 -2011) of observations on diurnal and seasonal variation of air CO2
from an urban station According to International Energy Agency India is the 4th largest emitting country of greenhouse gasses and is
mainly from coal based thermal power plants and biomass burning
The source value identified based on seasonal data (-14.6 ± 0.7‰) is
enriched compared to the value estimated based on diurnal variation.
It showed the possibility of involvement of CO2 emission from cement
industry, where the source of CO2 is basically limestone which is
isotopically enriched (2.0‰).
Using a conceptual two component mixing model, the proportional
contribution of CO2 emission from cement industry is identified for
individual years.
On seasonal scale, mixing ratio is found higher for
the dry seasons compared to the wet seasons. The
d13C of air-CO2 reaches maxima during the late
phase of wet seasons (Oct) and drops to minima
during dry seasons (April, May). A steady rise in
d13C of air-CO2 is seen in the samples collected as
southwest monsoon (SWM) advances.
Seasonal scale-similar
trend seen all years-lower
amplitude in 2011-La
Nina year-explained with
reduced biomass burning
and increased
productivity as a
consequence of
prominent La Nina
condition.
Higher amplitude of seasonal-variation-
compared to global-coastal-station-
Cabo de Rama and Seychelles
Acknowledgements:
Dr. Willi Brand and his research group at MPI for the JRAS air reference material
CSIRO Marine and Atmospheric Research - GASLAB, Aspendale, Victoria, Australia for permitting us to use the monthly flask data of air-
CO2 measurement for the station Cabo de Rama
Global Monitoring Division of NOAA's Earth System Research Laboratory for providing air-CO2 data for Seychelles and we further thank
Institute for Arctic and Alpine Research at University of Colorado for the isotopic ratio data of air-CO2 for the same
Ministry of Earth Science, Government of India, project MoES/ATMOS/PP-IX/09 for funding
Divecha Centre for Climate Change, IISc for financial support and Department of Science and Technology for funding the OASIS AIRMIX
cylinder and IAEA standards
Guha and Ghosh, 2012,
under review