Chamber VOC lab tour (6/11/07) Chamber VOC lab tour (6/11/07)

Hosted by Dr. Alex GuentherHosted by Dr. Alex GuentherPresented by Fuu-Ming Kai and Kathryn Alexander

What do we learn? Background of trace gas emission

measurements

Lab tour: explore various techniques and indoor experiments

Introduction Trace gas emission

Includes technological and natural sources Affect air quality

Emission Measurement Methods Micrometeorological methods Mass balance methods Tracer ratio methods

Micrometerological Methods Quantify the net movement of a trace

gas/particle in the turbulent boundary layer. (e.g. Eddy Covariance)

Advantages: Do not disturb the source

Issues must be considered Sampling time Sensor requirements Where to sample

Mass Balance MethodsFlux = dC/dt +U + S

U: the change due to transport S: chemical loss and productionFlux: exchange between the air and other components

MethodsEnclosure ApproachBoundary Layer ApproachGlobal Budget Approach

Tracer Ratio Methods Use a tracer gas to estimate the flux a

target gas. Requirement:

The tracer and target gases must have similar source distributions and be transported in a similar manner.

Advantages: No meteorological measurements or

dispersion modeling is required.

Laboratory Studies

1. Methanol and acetone emissions from vegetation

- Dominant chemicals to total Biogenic Volatile Organic

- Characterize variations in the emission rates- Use them as the basis of a new model

2. Response of biogenic isoprene emission to elevated ozone

- High isoprene emissions --> high ozone concentration - Conduct investigation under controlled laboratory

conditions

The Layout of BVOC lab

Simple demonstration Cover the leaf with black card, and observe

the change in CO2

Green House

Controlled greenhouse

MassSpectrometry

Infrared Analyzer(Licor)

For [CO2}

Ozone Detectors and misc.

GC(Gas

Chromatography)

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

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Closing down the Mesa Lab facilities

Leaf and Plant Studies

and developing

new Foothills Lab facilities

RECOVERY PERIOD

TC

DROUGHT PERIOD

Isoprene flux (nmol

m-2 s-1)

0

5

10

15

20

25

30

2/4/02 4/4/02 6/4/02 8/4/02 10/4/02 12/4/02 14/4/02 16/4/02 18/4/02 20/4/02

Photosynthetic flux

(μ mol m

-2 s-1)

0

2

4

6

8

Stomatal conductance

( mol m

-2 s-1)

0.00

0.02

0.04

0.06

0.08

Date15/3/02 17/3/02 19/3/02 21/3/02 23/3/02 25/3/02 27/3/02 29/3/02 31/3/02 2/4/02

Soil water content

(m3 m-3)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

(a)

(d)

(c)

(b)

Response of isoprene and photosynthesis to drought(Pegoraro et al. 2004)

Particle production occurs when ozone is added to plant chamber (VanReken et al. 2006)

Process study results are used to develop numerical algorithms suitable for regional and global modeling

It’s all about team work!!

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Thank you very much for Alex Guenther and his group members for giving the worthwhile tutorial and providing slides and pictures.