Ammonia measurements and metrology in the
context of research and policy questions
• NH3 concentrations orders of magnitude higher than “background” in
many parts of the globe due to anthropogenic activities
• NH3 not widely measured in compliance networks
• NH3 being a sticky, reactive chemical is challenging to measure well
• Metrological standards and tools need development
The ammonia measurement challenge
Aim: quantitative, molecule specific measurements fit to the purpose of the research
or policy question
Gas-phase extraction followed by analytical chemical
Direct gas phase measurement
On-line Off-line
Open path/remote Closed path/gas sampling
Target data quality?
accuracy: ±5% reference traceable calibrations
Temporal resolution?
Policy • The UN and related UN ECE to abate Acidification,
Eutrophication and Ground-level Ozone: set limits and reduction goals for ammonia in
signatory countries (Annex IX, revised 2012).
• In parallel the EU (2001/81/EC) applies even lower emission ceilings for NH3.
A revision as part of the Clean Air Policy Package shall ensure:applicability until 2020, new
reduction commitments for ammonia from 2020 and 2030.
• national reports to use EMEP Emission Inventory Guidebook, emission .
• Real AQ measurement data (as for SO2, NOx, CO, Benzene
and PM)NFR SOURCE CATEGORY SO2 NH3 1.A.1 Public power, cogeneration and
district heating A
1.A.2 Industrial combustion A 1.A.3.b Road transport C E 1.A.3.a 1.A.3.c 1.A.3.d 1.A.3.e
Other mobile sources and machinery
C
1.A.4 Commercial, institutional and residential combustion
B
1.B Extraction and distribution of fossil fuels
C
2 Industrial processes B E 3 Solvent use 4 Agriculture activities D 6 Waste treatment B 6 Disposal activities C E - Nature D E D: 100 to 300 % E: order of magnitude
(EMEP-EEA air pollutant emission inventory guidebook – 2013, Part A,
Chapter 5, Table 3-3)
UK National Ammonia Monitoring Network
Protocols and standards
• CEN committee standards• Currently passive sampler review in progress
• No on-line NH3
• EMEP Handbook of methods
• ACTRIS/WMO-GAW protocol developmentBest Practice delivered through the existing
organisations however preparing draft documents to
include important as process is slow
Due to continuous development of technologies and
scientific understanding it is important to write
inclusive, general protocols
Objectives:
� Produce and characterise improved gas mixture standards with
long term stability and lower uncertainty (~1% rel.)
� Develop improved gas mixture standard methods that are
traceable, mobile with uncertainty < 3 % rel.
Static gas mixture standards:
� levels: 10 and 100 µmol/mol
� 5 different treatments
� 2 mixtures per level,
treatment and partner
Realisation of gas standards and mixtures
Summary of validation of PSMs
Cylinder
number
Gravimetric
amount fraction/
µmol mol−1
Percentage deviation from gravimetric amount fraction when certified using:
NPL1657 NPL1659 NPL30718 NPL1844 NPL1769 NPL11269 NPL11268
NPL1657 100.05 − 0.42 + 0.10 + 0.15 − 0.60 − 0.82 − 0.07
NPL1659 100.00 + 0.42 + 0.53 + 0.57 − 0.18 − 0.40 + 0.36
NPL30718 99.95 −0.10 −0.52 + 0.05 − 0.70 − 0.92 − 0.17
NPL1844 100.29 −0.15 −0.57 −0.05 −0.75 −0.97 −0.22
NPL1769 101.16 + 0.60 + 0.18 + 0.70 + 0.75 − 0.22 + 0.54
NPL11269 100.01 + 0.83 + 0.40 + 0.93 + 0.98 + 0.22 + 0.76
NPL11268 100.02 + 0.07 − 0.36 + 0.17 + 0.22 − 0.53 − 0.75
• 7 mixtures analysed by NDIR analyser
• Validated using a “standard/unknown” routine
• Each mixture treated in turn as the “unknown” and certified against the
other six
Expanded (k = 2) uncertainty in the amount
fraction of ±2 %
Partners METAS and BAM work on 2 independent for
traceable mixtures (0.5 to 500 nmol/mol)
� Designs have been setup
� METAS investigated materials
and coated elements (MFCs, valves)
� Permeation devices have been
calibrated. New magnetic suspen-
sion balance (coated SS; p < 6 bar)
� METAS ReGaS1 is operational
Dynamic gas mixture standards
A CB
D
E
F G
HI
Types of measurementQuestion: Answer: Responses:
1. What type of ammonia
analyser(s) do you use?
Aerodyne QC-TILDAS
Thermo 17C
UV-DOAS
Piccaro G2103
Other CRD Spectrophotometer
Omnisens TGA-310
ABB Instruments NDIR URAS 26
CEH Delta Denuder
AiRRmonia
Innova 1412i Photoacoustic Analyser
Filter Pack
3
1
1
6
1
1
1
1
1
1
1
2. What inlet material(s) do
you use?
Teflon*
PTFE
PFA
SilcoNert2000 Stainless Steel
Stainless Steel
FEP
[*Stated only as Teflon, not which type]
5
9
3
2
4
1
Types of study I: Auchencorth Moss hourly data
Twigg et al. in prep. 2016
NH3 concentrations during 2012 in relation to wind speed for the wind sectors: NE (10˚ to 130 ˚), NW (230 ˚ to 360 ˚ to 10 ˚) and S (130 ˚ to 230 ˚). (Data are medians of 50
hourly measurements sorted by ascending order of wind speed).
Types of study I Effects assessment from passive sampler (Critical loads/levels)
Concentrations N Deposition
not exceeded
<= 0.5
0.5 – 1.01.0 – 2.0> 2.0
keq ha-1 year-1
Assessment of
Critical Loads
Exceedance
Jane Hall, Bangor
Critical
Levels
Exceedance
CBED
model
MetNH3 assessments
• Passive sampler chamber intercomparison
• Facility intercomparison (UBA)
• Active sampler intercomparison at Easter Bush (15th August- 15th September 2016)
• Passive sampler intercomparison, Whim NH3 manipulation experiment
Off-line testing
• Passive and active denuder intercomparison at NPL, ongoing
(previously discussed)
• Passive sampler intercomparisons at Whim Bog?
• Active vs passive during active instrumentation
intercomparison at Easter Bush
• CEN standard published
• Interlaboratory/manufacturer protocol developed?
Diffusive and denuder sampler exposure tests
Radiello holder
and cartridge
Gradko DIFRAM-
400 and
diffusion tube
CEH ALPHA
sampler and
Passam
ammonia
sampler
CEH DELTA
denuder
Non-extractive sampling
Most commercial spectrometers are based on infrared spectroscopy, though UV
instruments also developing
Confirmed parties for the intercomparison
• 12 universities and institutes (both research and metrological) + 6 SMES
• Instruments include:• Differential Optical Absorption Spectroscopy• Infrared absorption Spectroscopy – quantum cascade lasers either
using cavity ring down or multipass cell (both closed and open path methods)
• Photoacoustic spectrometer• Chemiluminescence• Rotating wet denuders with online IC• Flow injection analysis
Vehicle
gate
access
Pedestria
n access
Pedestria
n access
Whim Bog: Off-line ammonia metrology intercomparison
Contact: Sim Tang ([email protected])
Ammonia transect
Aug – Sept 2016: Intercomparison periodsOct -Nov 2016: Chemical analysisNov 2016 – Feb 2017: Collation and report
Example NH3 concentration profile along
transect
Passive Samplers from participating laboratories will be exposed along transect, in parallel with continuous measurements.
NH3 line release source
Transect downwind (NE)
Upwind (SW)
0.1
1.0
10.0
100.0
-20 30 80
NH
3( µ
g m
-3)
Distance (m)
WHIM (July 2015)Transect
0.1 m
0 m
Wet N plots
Ammonia transect
Strategy for standards AND data access required
• Mitigation and abatement evidence
• measurement strategy fits evidence needs
• These can be many fold…a. Emission factors
b. Emission mitigation
c. Concentration limits and exposures
d. Deposition calculations/fluxes
e. Impacts on ecosystems/PM/Human health
Use of calibration centres and test facilities
• Learn from the model of VOCs and NOx etc.• Establish centres of excellence• On-going annual checks and improvement plans• Plan for access for SMEs, researchers to regularly
check standards• Incorporate metrological standards (or close to
them!)
• concentration and fluxes both important, but different requirements for each
UKEAP monitoring
measurements
Modelling and
mapping pollutant
concentrations and
deposition
Critical Loads and
exceedence
mapping
Local
Environmental
Impact
Assessments
and planning
Screening tools
e.g. SCAIL
Public
access
to data
Measurements and models into policy and management
http://uk-air.defra.gov.uk
http://www.ceh.ac.uk/sci_programmes/UKEAP-Project.html
http://cldm.defra.gov.uk/index.htm
http://uk-air.defra.gov.uk/research/air-quality-modelling
Databases
EMEP
OSPAR
UK-Air
Air pollution information service
APIS
National and international assessments
atmospheric pollution and deposition to
the environment e.g. RoTaP, UNECE
http://www.apis.ac.uk/
http://www..scail.ceh.ac.uk/
EU compliance
modelling (PCM)
Secondary Inorganic
Aerosol
Site data used by other UK networks:• ECN
• LTMN
•
Current review of NH3 measurements
1980 1985 1990 1995 2000 2005 2010 20150
2
4
6
8
10
12
# IS
I pap
ers
mea
surin
g am
bien
t NH
3
• Work in progress, ISI papers n=85
�25 use “on-line” methods
�39 use “off-line” methods
�3 remote sensing
� Several use both
�Estimate I have got ~50%
papers, as often NH3 not
primary aim
Grey literature, unpublished data. Search on-going, please help!