PhD project: Quantifying photosynthetic carbon uptake using measurements of Carbonyl Sulfide | Linda Kooijmans | Research

Name: Linda Kooijmans

Supervisor:
Dr. Huilin Chen (Centre for Isotope Research, ESRIG/RUG)
Period: January 2014 - December 2017

Summary of PhD project:

A critical step in carbon modelling studies is to resolve both Gross Primary Production (GPP) and Respiration (Re). Although several methods have been proposed to partition the Net Ecosystem Exchange (NEE) into GPP and Re, large uncertainties still exist in quantifying these carbon fluxes. As a potential solution to this problem carbonyl sulfide (COS) was proposed as a tracer for photosynthetic CO₂ uptake as it is also taken up by plants, but not being released, and the vegetative uptake of COS is proportional to that of CO_2.

So far, the sources and sinks of COS are poorly known, which limits the ability of employing COS as a tracer for GPP. The aim of this PhD research is to identify what sources and sinks control atmospheric COS and CO₂ concentrations and to quantify GPP using COS measurements. In 2014 we have tested a quantum cascade laser (QCL) spectrometer (Aerodyne Research Inc., MA, USA) for continuous and simultaneous measurements of COS, CO₂, CO and H₂O at the Lutjewad atmospheric monitoring station in the Netherlands (Kooijmans et al., 2016). In the following years we measured COS and CO₂ concentrations and fluxes from the soil, leaves and ecosystem at a boreal forest site in Hyytiälä, Finland. With this dataset we are able to separate all flux components within the ecosystem and improve our understanding of the processes that control the COS fluxes. The knowledge gained from this study will be key in the use of COS as a tracer for GPP and will help carbon modelling studies to obtain accurate GPP estimates.

Kooijmans, L. M. J., Uitslag, N. A. M., Zahniser, M. S., Nelson, D. D., Montzka, S. A., and Chen, H.: Continuous and high-precision atmospheric concentration measurements of COS, CO2, CO and H2O using a quantum cascade laser spectrometer (QCLS), Atmos. Meas. Tech., 9, 5293-5314, doi: 10.5194/amt-9-5293-2016, 2016.