AYSENUR BICER

Dr. Hans Schuessler

Obtaining Dissolved From Ocean Water by Gas Separation System Analysis with Cavity-ring Down Spectroscopy

Why scientists examine ocean water ?

Outline

• How to get gas from natural sourcesA moored autonomous systemRobust SensorHeadspace analysisMembrane gas separator

• Which technique to analyze the data• Experimental results

• At the beginning of each cycle, the system generates a zero standard by cycling a closed loop of air to remove all of the CO2

• Next, the system is calibrated with a high standard reference gas, or “span "gas.

• The gas flows through the detector for CO2 analysis and is vented to the atmosphere through the air block.

• Once the detector is fully flushed, the flow is stopped and the system returns to atmospheric pressure.

A high-frequency atmospheric and seawater pCO2 dataset from 14 open-ocean sites using a moored

autonomous system

A. J. Sutton, C.L. Sabine, Earth System Science Data, A high-frequency atmospheric and seawater pCO2 dataset from 14 open-ocean sites using a moored autonomous system

• h-shaped equilibrator, which is mounted in a float designed to ensure the optimum depth for equilibration.

• The air cycles through the system by pumping air out of flexible tubing.

• While the air bubbles through the column of water, the air comes into equilibrium with the dissolved gases in the surface seawater.

• This air then returns to the system, passing through a silica gel drying agent

• The air then circulates through the equilibrator again. The rising air bubbles in the equilibrator create seawater circulation in the equilibrator by pushing the water up and over the horizontal leg of the equilibrator and out the short leg of the equilibrator. This draws new water into the long leg of the equilibrator, ensuring that the recirculated air is always in contact with new seawater.

A. J. Sutton, C.L. Sabine, Earth System Science Data, A high-frequency atmospheric and seawater pCO2 dataset from 14 open-ocean sites using a moored autonomous system

METHOD Their sensor converts of DIC to by acidification• 1 of sea water to of ~ 3.5

• in the gas phase is measured

Robust Sensor for Extended Autonomous Measurements of Surface

Ocean Dissolved Inorganic Carbon

Robust Sensor for Extended Autonomous Measurements of Surface Ocean Dissolved Inorganic Carbon, Andrea J. Fassbender,*,†, Christopher L. Sabine,‡ ∥Noah Lawrence-Slavas,‡ Eric H. De Carlo,§ Christian Meinig,‡ and Stacy Maenner Jones‡, Environmental Science

For the zero calibration, air inside the system is recirculated in the Zero LoopRobust Sensor for Extended Autonomous Measurements of Surface Ocean Dissolved Inorganic Carbon, Andrea J. Fassbender,*,†, Christopher L. ∥Sabine,‡ Noah Lawrence-Slavas,‡ Eric H. De Carlo,§ Christian Meinig,‡ and Stacy Maenner Jones‡, Environmental Science

For the high xCO2 calibration, a compressed calibration gas is flushed through the LI-820 optical chamber in the Span Pathway Robust Sensor for Extended Autonomous Measurements of Surface Ocean Dissolved Inorganic Carbon, Andrea

J. Fassbender,*,†, Christopher L. Sabine,‡ Noah Lawrence-Slavas,‡ Eric H. De Carlo,§ Christian Meinig,‡ and ∥Stacy Maenner Jones‡, Environmental Science

Air inside the instrument that was previously stripped of CO2 is bubbled through the acidified mixture and recirculated in the Equilibration Loop for 5 min to facilitate the transfer of CO2 ∼from the liquid into the gas phase.Robust Sensor for Extended Autonomous Measurements of Surface Ocean Dissolved Inorganic Carbon, Andrea J. Fassbender,*,†, Christopher L. Sabine,‡ Noah ∥

Lawrence-Slavas,‡ Eric H. De Carlo,§ Christian Meinig,‡ and Stacy Maenner Jones‡, Environmental Science

The acidified sample is then ejected from the equilibration chamber through the Evacuation Pathway Robust Sensor for Extended Autonomous Measurements of Surface Ocean Dissolved Inorganic Carbon, Andrea J. Fassbender,*,†, Christopher L. Sabine,‡ Noah ∥

Lawrence-Slavas,‡ Eric H. De Carlo,§ Christian Meinig,‡ and Stacy Maenner Jones‡, Environmental Science

Calculation of DIC

The sample DIC concentration is calculated by summing the number of moles of CO2 in the gas and liquid phases at equilibrium and dividing by the mass of the injected sample.Fugacity

Robust Sensor for Extended Autonomous Measurements of Surface Ocean Dissolved Inorganic Carbon, Andrea J. Fassbender,*,†, ∥Christopher L. Sabine,‡ Noah Lawrence-Slavas,‡ Eric H. De Carlo,§ Christian Meinig,‡ and Stacy Maenner Jones‡, Environmental Science

Determination of dissolved methane in natural waters using headspace analysis with cavity ring-down spectroscopy

Steps for headspace gas connections

• Add small amount of air into syringe while it is upright then the air and water expelled. Fill the syringe 70 ml of sample.

• 70 ml a volume of methane free zero air add to sample • Disconnect from cylinder of zero air • Open 3 way valve for pressure equilibrium within sample syringe• Place the sample in a shaker table for 30 minutes• Use a little head space gas to rinse pathway between two syringes• Transfer the headspace to other syringe• The head space was drown into the Picarro CRDS analyzer by pump. Hannah M. Roberts, Alan M. Shiller, Determination of dissolved methane in natural waters using

headspace analysis with cavity ring-down spectroscopy , Analytica Chimica Acta

Membrane gas separator

gas separation from liquid with a hollow fiber porous membrane

James Bound’s set up

Reservoir

Pump

Filter

Vacuum Pump

Water Bypass

Flow Controller

Hollow Fiber membrane

TC Vacuum Gauge

Gas Cylinder

Water Pump

Sample ReturnSample Input

Vacuum PumpPressureGauge

Exhaust

Gas output for Analysis

James Bound’s set up

James Bound’s set up

Cavity Ring-down Spectroscopy

1600.0 1600.5 1601.0 1601.50

5

10

15

20

Absorp

tion (1

0-6cm

-1)

Wavelength (nm)

Pressure ~130 Torr CRD Measurements

1.0% 12CO2

0.012% 13CO2

2.0% H2O

1600 1601 1602-0.0000002

0.0000000

0.0000002

0.0000004

0.0000006

0.0000008

0.0000010

Wavelength(nm)

Absorp

tion(a

rb)

0.000000

0.000002

0.000004

0.000006

0.000008

0.000010

0.000012

Experimental Data CO2(1.1)CO2-C13 CO2-C12 H2O

Hitra

n D

ata

base

Ocean water mix with airPressure is 140 Torr

Sources

• A. J. Sutton, C.L. Sabine, Earth System Science Data, A high-frequency atmospheric and seawater pCO2 dataset from 14 open-ocean sites using a moored autonomous system,

• Hannah M. Roberts, Alan M. Shiller, Determination of dissolved methane in natural waters using headspace analysis with cavity ring-down spectroscopy , Analytica Chimica Acta

• Robust Sensor for Extended Autonomous Measurements of Surface Ocean Dissolved Inorganic Carbon, Andrea J. Fassbender,*,†, Christopher L. Sabine,‡ Noah Lawrence-Slavas,‡ Eric H. De ∥Carlo,§ Christian Meinig,‡ and Stacy Maenner Jones‡, Environmental Science