This document proposes using research infrastructures (RIs) like the Integrated Carbon Observation System (ICOS) as modular platforms to expand reactive nitrogen (Nr) deposition monitoring in Germany. It suggests both short-term and long-term extensions. In the short-term, installing passive samplers and a roving eddy covariance system at ICOS sites could provide data to parameterize models for estimating Nr deposition. Temporary high-frequency measurements could calibrate these models. Long-term, adding total reactive atmospheric nitrogen converter (TRANC) systems to ICOS sites could directly measure total Nr fluxes. This would support national monitoring networks with little additional effort by utilizing existing ICOS infrastructure.

1. 17 Sep 2020
Slide #0 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
Research infrastructures as modular platforms for
reactive nitrogen deposition monitoring
Frederik Schrader and Christian Brümmer
Thünen Institute of Climate-Smart Agriculture
#ICOS2020SC Session 18
17 September 2020

2. 17 Sep 2020
Slide #1 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
Background – Haber-Bosch Nitrogen
Data source: Erisman et al. (2008); Smil (2002); Stewart (2005); digitised, extrapolated by OurWorldInData.org, own illustration; Photos source: Nobel Foundation

3. 17 Sep 2020
Slide #2 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
Background – Cascading effects of N deposition
Nitrous Oxide
(N2O) Particulate matter
& tropospheric O3
Fertilizer
manufacture
Natural
ecosystems
Nitrogen oxides
(NOx)
Ammonia
(NH3)
Leached nitrate
(NO3
-)
Nitrate in
streamwaters
Ammonium nitrate
in rain (NH4NO3)
Further emission
of NOx & N2O
carrying on the
cascade
GHG balance
Aquat. eutrophication
Crops for food &
animal feed
Livestock far-
ming for food
Atmospheric N2
fixed to reactive
nitrogen (Nr)
Terr. eutrophication
Soil acidification
Nr in
manure
Nr
Nr
N form in
the cascade
Environmen-
tal concerns
Intended
N flows
Unintended
N flows
Diagram redrawn after Sutton et al. (2011, European Nitrogen Assessment)

4. 17 Sep 2020
Slide #3 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
Motivation
There is a clear, yet unmet demand for a centrally
coordinated, large scale reactive nitrogen deposition
monitoring network in Germany
• Concentration measurements for individual compounds
only in few federal states
• Measurements often not focusing on ecosystem effects
(e.g. NOx primarily near sources)
• Experimental campaigns focusing on treatments
 Limited availability of observational data for pressing
research questions and environmental policy
 Can ICOS help us solve this problem?
?(Fleischer et al., 2013)
(ICOS Germany Ecosystem Network)

5. 17 Sep 2020
Slide #4 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
Short-term extension of the ICOS network:
Low-cost measurements + inferential modelling
CO2 EC-System
• Cost efficient
• Little additional work
• Established techniques
+ Passive samplers + Model
Illustrations: J.-P. Delorme, LI-COR, Photo: J. Rüffer

6. 17 Sep 2020
Slide #5 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
Short-term extension of the ICOS network:
Low-cost measurements + inferential modelling
Large uncertainties in NH3 deposition modelling when
using default, land-use specific parameters
• Dependence of non-stomatal deposition on humidity
and other atmospheric constituents?
• Contribution of stomatal fluxes?
• Sampling frequency of concentration data?
 Can be answered with ICOS routine measurements
and a single roving EC system

7. 17 Sep 2020
Slide #6 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
Short-term extension of the ICOS network:
Low-cost measurements + inferential modelling
1) Parameterisation of stomatal conductivity
from application of Ball-Berry model to NEE
(Schrader, Erisman, & Brümmer, 2020)

8. 17 Sep 2020
Slide #7 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
Short-term extension of the ICOS network:
Low-cost measurements + inferential modelling
2) Parameterisation of non-stomatal exchange
from observed RH response
(requires temporary flux measurements)
(Nemitz et al., 2014)

9. 17 Sep 2020
Slide #8 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
Short-term extension of the ICOS network:
Low-cost measurements + inferential modelling
Derivation of correction functions for low
temporal resolution of passive sampler data
 Necessary to get from monthly concentrations to 30 min fluxes
(but requires temporary high-freqency concentration measurements)
(Schrader et al., 2018)

10. 17 Sep 2020
Slide #9 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
Short-term extension of the ICOS network:
Low-cost measurements + inferential modelling
In summary: Initial temporary parallel high-frequency
measurements with roving system to …
1) parameterise stomatal conductance from NEE
2) parameterise non-stomatal conductance from RH
3) derive correction for temporal resolution bias
... allow for a successive upgrade of the ICOS network for
cheap, easy, and valid NH3 deposition estimates (Schrader et al., 2018)
(Schrader et al., 2020) (Nemitz et al., 2014)

11. 17 Sep 2020
Slide #10 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
Long-term extension of the ICOS network:
Additional high-frequency ∑Nr measurements
CO2 EC-System ∑Nr EC-System
(TRANC+CLD)
• Expensive
• Experimental
• But: first successful
long-term studies!
Illustrations.: J.-P. Delorme, LI-COR

12. 17 Sep 2020
Slide #11 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
NH3
HNO3
HNO2
pNH4
pNO3
NO
NO2
CO
Stainless steel tube Gold tube
FeNiCr tube
Power supply, 80 A, 5 V
NO
Total Reactive Atmospheric Nitrogen Converter
(Marx et al., 2012, Ammann et al., 2012, Brümmer et al. 2013)
Long-term extension of the ICOS network:
Additional high-frequency ∑Nr measurements

13. 17 Sep 2020
Slide #12 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
Long-term extension of the ICOS network:
Additional high-frequency ∑Nr measurements
New version allows for differentiation of
oxidised and reduced nitrogen compounds
(i.e. combustion vs. agriculture)
Currently being tested at the Gnarren-
burger Moor experimental site:
• ICOS standard setup
• N2O and CH4-EC
• TRANC 2.0 and NH3-EC
• associated studies on ET and export
 also feasible as pilot study for the
proposed short-term extension
TRANC 2.0 = TRANC 1.0
+ 2nd Gold tube (NOy)
+ dual-channel CLD
CO
CO
Stainless steel tube Gold tube
FeNiCr tube
Power supply, 80 A, 5 V
Gold tube
(Wintjen et al., in prep.)

14. 17 Sep 2020
Slide #13 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
Conclusions & Outlook
• ICOS setups allow for easy ‚modular‘ extension with additional variables
 Support (or setup) of national monitoring networks through existing infrastructure eliminates the
need to start from scratch
• Cheap and easy for Nr compounds through the installation of passive samplers or wet denuders
 Can provide important data for studies on GHG-Nr interaction with relatively little additional effort
• Model calibration and derivation of correction functions need high-frequency measurements
 Only temporary; single roving system possible; high pay-off in terms of validity of the flux estimates
• Long-term vision: Extension of the network with TRANC+CLD systems
 True total reactive nitrogen flux measurements at ICOS sites

15. 17 Sep 2020
Slide #14 Schrader & Brümmer
RIs as modular platforms for N deposition monitoring
Thanks for listening!
Comments & criticism welcome: frederik.schrader@thuenen.de
Thünen Institute of Climate-Smart Agriculture
www.thuenen.de/en/ak