Seasonal and Diurnal Variations in Atmospheric and Soil Air 14CO2 in a Boreal Scots Pine Forest

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Abstract

We present a radiocarbon (C-14) dataset of tropospheric air CO2 forest soil air CO2, and soil CO2 emissions over the course of one growing season in a Scots pine forest in southern Finland. The CO2 collection for C-14 accelerator mass spectrometry (AMS) analysis was done with a portable, suitcase-sized system, using molecular sieve cartridges to selectively trap CO2 The piloting measurements aimed to quantify the spatial, seasonal and diurnal changes in the C-14 content of CO2 in a northern forest site. The atmospheric samples collected above the canopy showed a large seasonal variation and an 11 parts per thousand difference between day and nighttime profiles in August. The higher Delta C-14 values during night are partly explained by a higher contribution of C-14-elevated soil CO2, accumulating in the nocturnal boundary layer when vertical mixing is weak. We observed significant seasonal trends in Delta C-14-CO2 at different soil depths that reflected changes in the shares of autotrophic and heterotrophic respiration. Also the observed diurnal variation in the Delta C-14 values in soil CO2 highlighted the changes in the origin of CO2, with root activity decreasing more for the night than decomposition.
Original languageEnglish
JournalRadiocarbon
Volume60
Issue number1
Pages (from-to)283-297
Number of pages15
ISSN0033-8222
DOIs
Publication statusPublished - Feb 2018
MoE publication typeA1 Journal article-refereed

Fields of Science

  • 1172 Environmental sciences
  • atmosphere
  • carbon dioxide
  • radiocarbon
  • soil
  • CARBON BALANCE
  • CO2 EFFLUX
  • C-14 DATA
  • RESPIRATION
  • DYNAMICS
  • ROOT
  • RADIOCARBON
  • ALLOCATION
  • EXCHANGE
  • DIOXIDE

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