© 2015 Picarro Inc.

Picarro G5131-i

d15N, d15Na, d15Nb, d18O in N2O

Mid-IR Isotopic N2O Analyzer

© 2015 Picarro Inc.

Why measure N2O isotopes?

• N2O is a potent GHG (~ 300x Global Warming Potential of CO2)

– Loss of N2O from soils

– Emissions from wastewater treatment plants

– Oceanographic productivity and nitrogen cycling

• N2O is a pre-cursor for NOx in the upper atmosphere and plays an important role in regulating stratospheric ozone

• Isotope of N2O can be used to probe sources and sinks in the global nitrogen cycle

– Identify nitrification and denitrification processes in soils and water

– Investigate terrestrial N2O cycles to improve predictive models and better understand human contributions to global warming

– Investigate oceanic N2O cycles

• Humans are impacting the global N cycle everyday.

– We now add more N to the environment than is naturally fixed.

© 2015 Picarro Inc.

Global Nitrogen Cycle

• Nitrification and denitrification occurs through many pathways

• Nitrogen isotopes, including site-specific isotopic information, can be used to

trace these pathways

– Different processes produce N2O with different isotopic composition

https://grdc.com.auhttp://www.whoi.edu

Marine N Cycle Terrestrial N Cycle

© 2015 Picarro Inc.

Introduction to N2O Isotopes

• Reference scale for N isotopes is Air

• Reference scale for O isotopes in N2O

is typically VSMOW (but can be Air)

d15Na = 14N-15N-16Od15Nb = 15N-14N-16O d18O = 14N-14N-18O

Isotope Abundance (%)

14N 99.636

15N 0.364

16O 99.757

17O 0.038

18O 0.205

𝛿18𝑂 = 18𝑂 16𝑂

𝑠𝑎𝑚

18𝑂 16𝑂𝑠𝑡𝑑

− 1 1000

𝛿15𝑁 = 15𝑁 14𝑁

𝑠𝑎𝑚

15𝑁 14𝑁𝑠𝑡𝑑

− 1 1000

Site Preference = d15Na - d15Nb

© 2015 Picarro Inc.

Atmospheric budget of N2O

• The budget of atmospheric N2O is controlled by three major components:

– Flux of N2O from soils

– Mixing from the stratosphere

– Flux of N2O from the oceans

• Human activity is impacting the

global N2O cycle:

– Intensive agriculture

– Positive feedbacks associated a

warming climate

• The Picarro Advantage:

– N2O concentration precision (< 0.05

ppb) can identify rising N2O in the

well-mixed atmosphere

– Low drift (< 0.1 ppb) decreases time

spent on calibration

– Isotopes can identify sources and

sinks of N2O

1. Ice core records show increasing N2O

concentrations from 270 ppb prior to the Industrial

Revolution to over 300 ppb today

2. Field sites around the global today show N2O is

well-mixed in the atmosphere and has increased by

about 5% since the late 1970s (~ 300 to 315 ppb)

Ka

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(20

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), P

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Th

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,

Jo

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ität

1

2

© 2015 Picarro Inc.

Soils: a significant flux of N2O to the atmosphere

• Agricultural emissions and emissions from natural soils account of between

56 and 70% of all global N2O sources (Syakila and Kroeze, 2011, doi:10.3763/ghgmm.2010.0007)

• Isotopes (d15N, d18O, d15Na, d15Nb) can be used to distinguish sources of N2O

flux

– N2O produced during nitrification is more depleted in 15N and 18O relative to the initial

substrate than N2O produced during denitrification

– The site location of the heavy 15N isotope can also help as different microbial

processes exhibit different site preference

• Picarro G5131-i can be used for:

NATURAL ABUNDANCE STUDIES

• Used in natural or unfertilized

systems

• Bulk isotopes (d15N, d18O) and site

preference (d15Na, d15Nb)

TRACER STUDIES

• Distinguish between nitrification and

denitrification following addition of

enriched fertilizers, e.g., 15N-NH4+ or

15N-NO3-

• Coupled 15N/18O enrichment

approaches are also being developed

© 2015 Picarro Inc.

The importance of N in the oceans

• The world’s oceans contribute about 30% of the atmospheric N2O budget

making them a significant source of this important GHG

– Nitrification dominates production of N2O

– Denitrifcation contributes only 7-35 % of N2O produced in the water column

– Amount of N2O produced in world’s ocean is dependent on dissolved O2

concentrations (enhanced under low O2)

• N2O emissions from the ocean will likely increase in the future due to:

1. Climate change, and the associated warming ocean temperatures, is expected to

expand the open ocean’s Oxygen Minimum Zones

2. Enhanced continental run-off and input of nutrients to the ocean will expand coastal

anoxic zones

© 2015 Picarro Inc.

Measure dissolved N2O with a Picarro G5131-i

• Oceanographers are typically interested in measuring N and O isotopes in

two forms:

Dissolved N2OBiologically-available N via

the denitrifier method

• Compatible with the compact

Picarro G5131-i

• Measure dissolved N2O and d15N

and d18O using an equilibration

device or head-space analysis

• Denitrifier methods produce only

a small amount of concentrated

N2O

• Dedicate your IRMS to the

denitrifier method and analyze

dissolved N2O with your Picarro

Dissolved gas set-up used by Erler et al.

(2015) with Picarro G5101-i

© 2015 Picarro Inc.

Picarro G5131-i: i-N2O in the air, water and soil

• The Picarro G5131-i is:

– Compact: the most compact analyzer on

the market for high-precision d15N, d15Na,

d15Nb and d18O.

– Precise and stable: Stability on the Picarro

platform allows you to average data for

longer and improve the precision of your

N2O concentration and isotope

measurements.

– Engineered for high performance: Tight

temperature and pressure control with a

small cavity enables superior performance in

the lab or in the field. Time-based

measurements avoid challenges associated

with laser fluctuations.

– Maximum versatility: measure small,

discrete gas samples, dissolved gases or

ambient atmospheric measurements.

© 2015 Picarro Inc.

Interfacing the G5131-i with Picarro Peripherals

Small Sample Introduction Module 2 16-Port Valve Manifold

The G5131-i is not compatible with Closed Systems operation (A0701, A0702).

© 2015 Picarro Inc.

Technical Specifications &

Performance of the Picarro G5131-i

© 2015 Picarro Inc.

Performance Specifications for G5131-i

© 2015 Picarro Inc.

G5131-i Spectroscopy

N2O peak

a and b peaks on wings

of large N2O peak

Distinct, separate

N218O peak

Area of weak water absorption & weak interference from CO2

© 2015 Picarro Inc.

Allan Deviation for Picarro G5131-i

stable to > 1 hour

0.5 ‰

0.02 ppb

© 2015 Picarro Inc.

Testing Precision on G5131-i

[N2O] (ppb) 1s Precision(100 sec)

1s Precision (10 min; 600 sec)

G5131-i 0.028 0.018

Specification 0.1 0.05

N2O @ 340 ppb

N2O

co

ncen

trati

on

(p

pb

)

© 2015 Picarro Inc.

Testing Precision on G5131-i

d15Na / d15Nb (‰) 1s Precision(100 sec)

1s Precision (10 min; 600 sec)

G5131-i 0.7 / 0.8 0.3 / 0.4

Specification 1.0 0.5

N2O @ 340 ppb

d1

5N

a(‰

)

d1

5N

b(‰

)

© 2015 Picarro Inc.

Testing Precision on G5131-i

d18O (‰) 1s Precision(100 sec)

1s Precision (10 min; 600 sec)

G5131-i 0.8 0.35

Specification 1.0 (300 sec) 0.7

N2O @ 340 ppb

d1

8O

(‰

)

© 2015 Picarro Inc.

Testing Drift on G5131-i

G5131-i Prototype Typical

[N2O] (ppb) 0.012 0.1

d15Na, d15Nb (‰) 0.4 / 0.3 2

d18O (‰) 0.3 2

© 2015 Picarro Inc.

Ability to measure small samples using the SSIM2

G5131-i

SSIM2

20 ml gas samples

for i-N2O analysis

© 2015 Picarro Inc.

Example Applications and Customer

Data

© 2015 Picarro Inc.

Picarro i-N2O for studying emissions from crop residue

• Soil incubations with crop residue (wheat, pea, canola, flax) spiked with 15N

and 13C

• Headspace analysis of evolved N2O (d15N) for daily and cumulative emission

from each treatment

• Under conditions of nitrification, the N source (crop residue type) had a

significant effect on N2O emissions while under denitrification there was

considerable potential for N2O emissions from crop residue

0 0.1 0.2 0.3 0.40.00

0.05

0.10

0.15

0.20

0.25

0.30

Re

sid

ue-d

eri

ved

N2O

em

iss

ion

(mg

N)

Urea Wheat Pea Flax Canola

0 2 4 6 8 10 120.00

2.00

4.00

6.00

8.00

Total N2O emission (mg N)

Re

sid

ue-d

eri

ve

dN

2O

em

issio

n(m

gN

)

0 0.1 0.2 0.3 0.40.00

0.05

0.10

0.15

0.20

0.25

0.30

Re

sid

ue-d

eri

ved

N2O

em

iss

ion

(mg

N)

Urea Wheat Pea Flax Canola

y = 0.585x - 0.0126

R2 = 0.937***

y = 0.675x + 0.099

R2 = 0.997***

0 2 4 6 8 10 120.00

2.00

4.00

6.00

8.00

Total N2O emission (mg N)

Re

sid

ue-d

eri

ved

N2O

em

issio

n(m

gN

)y = 0.244x + 0.037

R2 = 0.906***

Result from denitrification

experiment

G5101-i (d15N only) in Professor Rich

Farrell’s lab at University of Saskatchewan

Headspace

samples

For more information, see the Picarro webinar with Prof. Farrell.

© 2015 Picarro Inc.

Recent dissolved N2O results with Picarro

• For environments with variable

concentrations of O2, CO, CO2 and CH4 and

H2S care should be taken to limit or correct

spectral interference on d15N-N2O.

• However, with the appropriate chemical

removal or correction, an excellent

comparison to GC-IRMS can be achieved.

• Picarro recommends physical traps for the

removal of:

– H2O vapor (Drierite)

– H2S (Cu trap)

– CO (Pt catalyst)

– CO2 (Ascarite)

• For environments with variable O2 mixing

ratios, an instrument specific correction is

recommended. Erle

re

t a

l. (

20

15

), d

oi: 1

0.1

002/lom

3.1

00

32

© 2015 Picarro Inc.

Other resources for learning about N2O

• Picarro Webinar

– Using Nitrogen Isotopes to Partition N2O Emissions in Agriculture

• Professor Richard Farrell, University of Saskatchewan and Dr. Nabil Saad, Picarro

• http://www.picarro.com/resources/webinars/using_nitrogen_isotopes_to_partition_n2o_emission

s_in_agriculture

• Publications

– Peng et al. (2014), “The effect of dissolved oxygen on N2O production by ammonia-

oxidizing bacteria in an enriched nitrifying sludge”, Water Research,

doi:10.1016/j.watres.2014.08.009

• http://www.picarro.com/resources/literature_publications/the_effect_of_dissolved_oxygen_on_n2

o_production_by_ammonia_oxidiz

– Erler et al. (2015) “Applying cavity ring-down spectroscopy for the measurement of

dissolved nitrous oxide concentrations and bulk nitrogen isotopic composition in

aquatic systems: Correcting for interferences and field application”, Limnology and

Oceanography: Methods, doi:10.1002/lom3.10032

• http://www.picarro.com/resources/literature_publications/applying_cavity_ring_down_spectrosco

py_for_the_measurement_of_diss

© 2015 Picarro Inc.

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• The World Meteorological Organization’s

(WMO) gold standard instrument for GHG

measurements

• Hundreds of instruments, installed in more

than 50 countries, on all seven continents

• Used & recommended by the world’s leading

scientists and government bodies

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