Chapter 64
Biological Activity in Clouds: From
the Laboratory to the Model
L. Deguillaume, H. Perroux, N. Wirgot, C. Mouchel-Vallon, N. Chaumerliac,
M. Joly, V. Vinatier and A.-M. Delort
Abstract Microorganisms are present in the atmosphere and can survive in cloud
droplets. They are able to transform organic compounds and can consequently compete with radical chemistry. Because the cloud system is a complex multiphase
medium, the efficiency of biodegradation by cloud microorganisms has to be evaluated by numerical models of different complexity simulating multiphase chemical
processes in clouds. However, only abiotic processes are taken into account in these
numerical tools. The objective of this work was thus to integrate biological data in
an atmospheric cloud chemistry model and to evaluate the effect of microorganisms
in the transformation of chemical compounds. For this, experimental biodegradation rates of acetic and formic acids, formaldehyde and hydrogen peroxide by various bacterial representative of cloud biodiversity were experimentally measured.
These values have been implemented in a cloud chemistry model describing aqueous phase chemistry with the explicit CLEPS (Cloud Explicit Physico-chemical
Scheme) mechanism. Several simulations with and without biodegradation processes
have been performed changing temperature (5 °C or 17 °C) and actinic flux to simulate summer or winter conditions. The chemical scenario (gas concentrations and
emission/deposition) is representative of low-NOx emission with significant isoprene
emissions.
64.1 Introduction
Numerical models of different complexity have been developed in the past to simulate
cloud chemistry. Currently, only abiotic processes are implemented in these models.
L. Deguillaume (B) · H. Perroux · C. Mouchel-Vallon · N. Chaumerliac
Université Clermont Auvergne, CNRS LaMP, 63000 Clermont-Ferrand, France
e-mail: L.Deguillaume@opgc.fr
N. Wirgot · M. Joly · V. Vinatier · A.-M. Delort
Université Clermont Auvergne, CNRS, SIGMA Clermont, ICCF, 63000 Clermont-Ferrand, France
C. Mouchel-Vallon
NCAR, National Center for Atmospheric Research, Boulder, CO, USA
© Springer Nature Switzerland AG 2020
C. Mensink et al. (eds.), Air Pollution Modeling and its Application XXVI,
Springer Proceedings in Complexity,
https://doi.org/10.1007/978-3-030-22055-6_64
401
Biological Activity in Clouds: From
the Laboratory to the Model
L. Deguillaume, H. Perroux, N. Wirgot, C. Mouchel-Vallon, N. Chaumerliac,
M. Joly, V. Vinatier and A.-M. Delort
Abstract Microorganisms are present in the atmosphere and can survive in cloud
droplets. They are able to transform organic compounds and can consequently compete with radical chemistry. Because the cloud system is a complex multiphase
medium, the efficiency of biodegradation by cloud microorganisms has to be evaluated by numerical models of different complexity simulating multiphase chemical
processes in clouds. However, only abiotic processes are taken into account in these
numerical tools. The objective of this work was thus to integrate biological data in
an atmospheric cloud chemistry model and to evaluate the effect of microorganisms
in the transformation of chemical compounds. For this, experimental biodegradation rates of acetic and formic acids, formaldehyde and hydrogen peroxide by various bacterial representative of cloud biodiversity were experimentally measured.
These values have been implemented in a cloud chemistry model describing aqueous phase chemistry with the explicit CLEPS (Cloud Explicit Physico-chemical
Scheme) mechanism. Several simulations with and without biodegradation processes
have been performed changing temperature (5 °C or 17 °C) and actinic flux to simulate summer or winter conditions. The chemical scenario (gas concentrations and
emission/deposition) is representative of low-NOx emission with significant isoprene
emissions.
64.1 Introduction
Numerical models of different complexity have been developed in the past to simulate
cloud chemistry. Currently, only abiotic processes are implemented in these models.
L. Deguillaume (B) · H. Perroux · C. Mouchel-Vallon · N. Chaumerliac
Université Clermont Auvergne, CNRS LaMP, 63000 Clermont-Ferrand, France
e-mail: L.Deguillaume@opgc.fr
N. Wirgot · M. Joly · V. Vinatier · A.-M. Delort
Université Clermont Auvergne, CNRS, SIGMA Clermont, ICCF, 63000 Clermont-Ferrand, France
C. Mouchel-Vallon
NCAR, National Center for Atmospheric Research, Boulder, CO, USA
© Springer Nature Switzerland AG 2020
C. Mensink et al. (eds.), Air Pollution Modeling and its Application XXVI,
Springer Proceedings in Complexity,
https://doi.org/10.1007/978-3-030-22055-6_64
401