Sub-pools

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General Annex –
Characterisation of pools and flows
1 Introduction
This annex serves to provide a guidance common to all annexes (pool) on:




A systematic nomenclature of pools and sub-pools including how a unique identifier is
constructed
How N flows are unambiguously identified
Nitrogen compounds
Nitrogen-containing materials serving as ‘matrix’ for N flows
2 Codification of pools and flows
For the purpose of numerical handling an unique (numeric) ID must be given to each (sub)pool and
flow.
For the purpose of readability a unique (textual) code can be given to each (sub)pool and flow
2.1 Pools
All pools have a two-letter code and a unique pool-ID, which conceptually follows the UNFCCC and
NFR reporting of greenhouse gases and air pollutants.
IDs that deviate systematically from these reporting guidelines is marked with an asterisks (e.g., 6*
below). Deviation from the original sort order of the guidance document is caused by a general
changeover in coding by UNFCCC, to move from a system of 6 categories to one of 5 categories. The
pools that need to be considered include also the pool ‘Rest of the World’ for the quantification of
flows that enter or exit the national boundaries.
1
2
3
4
5
6*
7*
8*
9*
EF
MP
AG
FS
WS
HS
AT
HY
RW
Energy and Fuels
Materials and products (not used in your annex!)
Agriculture
Forest and Semi-natural Vegetation
Waste
Humans and Settlements
Atmosphere
Hydrosphere
Rest of the world
2.2 Sub-pools
All sub-pools have a two-letter code to be combined with the two-letter code of their parent pool as
well as a one-letter code which is combined with the pool-ID and following conceptually the UNFCCC
and NFR reporting systems. Also here CRF coding is maintained whenever possible, and asterisks
denote a deviation from that principle. For example, the agriculture pool has three sub-pools: animal
husbandry (AH or 3A), manure storage and management (MM or 3B) and soil management (SM or
3D).
Note that for the sake of simplicity, sub-pools can be referred to also as ‘pools’, as long as they are
clearly defined.
ID
3A
3B
3D
AH
MM
SM
Agriculture Animal husbandry
Agriculture Manure management and manure storage
Agriculture Soil management
To be completed authors of the guidance documents for
the different pools!
2.3 Sub-sub pools.
Many sub-pools need to be further sub-divided for the purpose of the construction of a NiNB. For
example, data collection and calculation for the AGAH pool needs to be done at the level of animal
types. The decision on the number of sub-sub pools and the level of detail depends on the national
circumstances. If applicable, the annexes will contain some guidance to facilitate the choices to be
made.
The identification of sub-sub pools shall be done by a systematic approach:
(1) Each sub-sub pool must be identified by a number, which is added to the ID code of the
subpool. For example, dairy and non-dairy cattle could have the IDs 3A1 and 3A2. Again, the
coding follows guidance as in CRF, as long as this is possible.
(2) Further subdivision should be avoided – if absolutely needed, it should determined using
lower case letters, e.g. 1A2f – again, following CRF when available, which will hardly be the
case.
Each sub-sub pool can be identified by a two-four letter ‘code’ that can be freely chosen by national
NiNBs experts. Harmonisation between countries is nevertheless favorable, thus the annexes will
contain some guidance, if applicable. For example, dairy and non-dairy cattle could be identified by
the acronyms DAIR and NDAI or DC and NC, respectively.
3 Nitrogen contents
For the identification of ‘what’ is flowing the following definitions are made:

Nitrogen forms (see also main guidance document): There are thousands of individual
chemical compounds containing nitrogen that are listed by Chemical Abstract Services (CAS).
Nitrogen contents can be assessed from the chemical formulae by stoichiometry using the


respective atomic and molecular weights (see e.g. Supplementary Information to Pelletier &
Leip, 2014). Examples for important nitrogen forms are ammonia (NH3), nitrous oxide (N2O)
or also total nitrogen (Ntot).
Matrices: total nitrogen flows embedded in a matrix with a fixed N content. Examples for
important matrices are food products (soft wheat, eggs, wood, explosives, ..). Methods are
available to assess the respective nitrogen contents, which in practice will cover a range. In
case the table lists N content estimates from different sources with ‘conflicting’ values, the
expert shall identify those values that are most suitable for the national conditions.
Media: Environmental nitrogen emissions often occur in a medium such as ‘exhaust fume’ or
‘surface water’ where the N content is variable and dynamic.
Table xx presents calculated nitrogen contents for relevant nitrogen forms, and typical measured or
estimated nitrogen contents of important matrices. These values shall be used to convert the flows
of total mass of nitrogen form or matrix to the flow of mass of which is required for NNBs.
Each nitrogen form or matrix is identified by a ‘code’. Table xx gives the code for the listed nitrogen
forms and matrices. However, it is possible that NiNBs experts wish to include other matrices can do
so, however harmonization between countries is nevertheless favorable.
a) Nitrogen forms
Acronym Chemical
formula or
source
N2
N2
NH3
NH3
N
content
[%]
100
82.35
Nitrogen oxides1
Nitrous oxide
Urea
Ammonium nitrate
Ammonium sulfate
20/20/20 fertilizer
NOx
N2O
UREA
AMMN
AMMS
30.43
63.64
46.67
35.00
21.21
20
b) Matrix*
State
description
Protein
Acronym N content Data source
[%]
PROT
16
XXX
Solid/liquid
Egg
Meat
EGG
MEAT
2.02
3.5-5.3
XXX
XX
--
Manure
MANU
1-3
XXX
Liquid/solid
Milk
MILK
0.5
XXX
Liquid
Polymer of different
amino acids
N mainly in egg protein
N mainly in meat
protein
Urea or uric acid (for
chicken manure) are
important components
N mainly in milk protein
Molecular nitrogen
Ammonia
1
NOx
N2O
(NH2)2CO
NH4NO3
(NH4)2SO4
By definition, NOx emissions are expressed as mass of NO2
State
Gas
Gas (or
aqueous
solution)
Gas
Gas
solid
solid
solid
solid
description
in
fertilizer
fertilizer
fertilizer
fertilizer
Wood
WOOD
0.05
To be completed
authors of the
guidance
documents for the
different pools!
*) Substance in which N is embedded
xxx
Solid
Forest products
4 Flows
All flows will be given in tons N per year. At a minimum, flows of more than 100 g N/person and year
need to be reported by a given country. A nitrogen budget covers reactive nitrogen compounds only.
Flows of molecular nitrogen (N2) and other fully unreactive forms (e.g., N in mineral oil, or in
polymer fibers) need not to be considered – see details in the respective pool descriptions. For a
unique identification of a flow the following information should be given:
(1)
(2)
(3)
(4)
The pool the flow starts / is flowing out of (poolex)
The pool the flow ends / is flowing into (poolin)
The martix in which the nitrogen is transported between poolex and the poolin
The nitrogen form of any other information considered relevant to distinguish, e.g. (i) the
compound that flows between the ex-pool and the in-pool (if no information is given it is by
default total N), (ii) additions like max (maximum) or min (minimum) etc.
The first three topics are always required. The fourth information is required in case the first three
are not uniquely identifying a flow, or if the NNB expert wishes to provide some additional
information. Start and end pools should be indicated at the highest level of detail the flow has been
quantified. For example, the start pool of manure excretion from fattening pigs would be AGAHPIGF.
In the case of environmental emission flows, where a nitrogen form is transported in a medium, the
matrix is considered to be the nitrogen form itself. Thus, information about poolex, poolin and the N
form is required.
In some cases, flows between the same pools and in the same matrix might use different pathways
or different media, such as for example N emissions to the hydrosphere could use surface water or
groundwater. If such distinctions are captured in a NNB, the fourth type of information is required.
In analogy to the pool description, we employ the pool system with codes to mark starting and
endpoint, as well as the code of the matrix. The codes of the four types of information are separated
by dashes.
Poolex
Poolin
Matrix*
Other
info
Total code
MP
AGAHNDAI
SOYC
-
MP-
Annex
Description
where
guidance is
given
3
Soya cake in compound
AGAHNDAISOYC
AGSM
AT
NH3
AGSM-ATNH3
AGSM
HY
NO3
Runoff in AGSM-HYsurfaces
NO3waters
SURFW
feed fed to non-dairy
cattle from industrial
processing
Ammonia emission to
the atmosphere from
agricultural soil
management
surface water runoff
NO3-N losses to the
hydrosphere
from
agricultural
soil
management
N2O-N
More examples to be
added.
*) Substance in which N is embedded
5 References
Pelletier, N., & Leip, A. (2014). Quantifying anthropogenic mobilization, flows (in product systems)
and emissions of fixed nitrogen in process-based environmental life cycle assessment:
rationale, methods and application to a life cycle inventory. The International Journal of Life
Cycle Assessment, 19(1), 166–173. doi:10.1007/s11367-013-0622-0
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