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Amsterdam Island
-VOCs-
| Observation |
| Category |
: |
Air sampling observation |
| Situation |
: |
ongoing |
| Time zone |
: |
Local time +5 |
| Sampling |
| Sampling height |
: |
70 |
| Description |
: |
flask |
| Sampling and analysis frequency |
: |
Atmospheric dimethysulfide (DMS): One sample taken every day at 08:00 LT since 1987. |
| Sampling environment |
: |
Sampling performed at Base Martin de Viviès (GEOPHY building).
No local sources of contamination. |
| Description for sampling analysis |
: |
Sampling inlet: Bulk
Sampling Line: 4m (1/4" O.D. Teflon).
Sampling flasks: 6-L stainless steel.
On-site measurements (every 7 days) using GC-SCD technique. Storing time of flasks between 1 and 7 days.
Injected air volume: typically 2.5L |
| Instrument and Analysis |
| Measurement method |
: |
Gas Chromatography (other) |
| Current status and history of instrument |
: |
1987-1998: Analyses performed using GC-FPD technique (VARIAN 3400).
1999-2009: Analyses performed using GC-SCD (GC = Shimadzu GC14B; SCD = SIEVERS 355 SCD) |
| Description of instrument |
: |
SCD provides linear response to S at picogram levels.
Measurement range: 0.5-5 ng of DMS
Detection limit = 0.1 ng(DMS)
Measurement technique:
Purge & Trap (cryotrapping at -60°C using Tenax GC80)
Column specification: Filled column "chromosil 310" kept at 90°C |
| Calibration |
| Current scale employed in the measurement |
: |
Atmospheric DMS concentrations expressed in pptv (party per trillion by volume). |
| Measurement calibration |
: |
Calibration performed using DMS permeation tubes (VICI metronics) with flowrates typically of 1ng(DMS)/min at 30°C (He flowrate of 30ml/min).
DMS analyses performed once per week (e.g. one day every 7 days). Calibration is performed during this day (less than few hours before atmospheric analyses) |
| Scale and calibration(treasability) |
: |
Weekly calibrations: Permeation tube of 1.05ng(DMS)/min
Yearly calibration of permeation tube: Using a second permeation tube (7.9 ng(DMS)/min) used since 1987 and calibrated both gravimetrically and using DMS(P) standards (Sciare et al., JGR, 2000) |
| Data Processing |
| Measurement unit |
: |
ppt |
| Data processing |
: |
Analyses performed twice with less than 5% difference |
| Processing for averaging |
: |
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| Data flag |
: |
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| Data remarks |
: |
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| Other Information |
| Scientific aim |
: |
Biogeochemical sulfur cycle (contribution to CCN). |
| Reference |
: |
1. Sciare, J., N. Mihalopoulos, and B. Nguyen. Summertime seawater concentrations of dimethylsulfide in the western Indian Ocean: Reconciliation of fluxes and spatial variability with long-term atmospheric observations. J. Atmos. Chem., 32, 357-373, 1999
2. Sciare, J., N. Mihalopoulos, and F. Dentener, Interannual variability of atmospheric dimethylsulfide in the Southern Indian Ocean. J. Geophys. Res., 105, 26,369-26,377, 2000
3. Sciare, J., N. Mihalopoulos, and E. Baboukas, Short-term variations of dimethylsulfide and its oxidation products at Amsterdam Island during summer time. J. Atmos. Chem., 39, 281-302, 2001 |
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| submitted by Laboratoire des Sciences du Climat et de l'Environnement |
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