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Iskrba
-NO2-
| Observation |
| Category |
: |
Air sampling observation |
| Situation |
: |
ongoing |
| Time zone |
: |
Local time +1 |
| Sampling |
| Sampling height |
: |
4 |
| Description |
: |
filter |
| Sampling and analysis frequency |
: |
Continuous 24h sampling through iodide impregnated glass sinter filters. Filter exchange takes place at 8:00AM UTC+1 every day.
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| Sampling environment |
: |
Iskrba monitoring site is regional station, part of the Slovenian national monitoring network for monitoring the background air polution. It is located on a plateau at approximately 500 m a.s.l. in a prevalently woody area and within transitional climate zone. The plateau is surrounded by the hills and mountains of approximately 800-1200 m a.s.l.. The surrounding area is mostly forest (prevailingly coniferous trees). The rest is grass land (not grassed by domestic animals) and partly also farmed (grass, pasture). |
| Description for sampling analysis |
: |
Continuous 24-hour sampling with air flow of about 0,5 liters per minute through the glass filter impregnated with sodium iodide (NaI) and sodium hydroxide (NaOH). Nitrogen dioxide is absorbed in the filter and reduced by iodide to nitrite (NO2-). The hydroxide is due to uptake of carbonate during the sampling converted to carbonate. The nitrate formed on the glass filter solution of trietanolamin is used. The nitrite concentration is determined photometricaly by the Gries method. Filter exchange takes place at 8:00 AM UTC+1 every day. |
| Instrument and Analysis |
| Measurement method |
: |
Spectrophotometry |
| Current status and history of instrument |
: |
Sampling instrument:
2004 – presnt; NILU SS2000 Sequential Air Sampler with Nitto vacunm pump Model VPO 125; NILU, Department for instruments and field sampling
Chemical Analysis:
2004-1.1.2007 – no history available
1.1.2007 to 27.08.2007; UV-VIS Spectrophotometer HP 8453; Hewlet Packard
29.08.07 – present; UV-VIS Spectrophotometer Cary 50 Conc; Varian
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| Description of instrument |
: |
Sampling:
SS2000 Sequential Air Sampler with Nitto vacunm pump Model VPO 125 (Free air flow up to 7 L/min).
Chemical analysis:
Linearity: 0,02-0,50 ugN/mL
Calibration curve: 0,02 - 0,5 ugN/mL.
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| Calibration |
| Current scale employed in the measurement |
: |
Observers standard scale. |
| Measurement calibration |
: |
Sampling:
Air flow is checked every month vs. calibrated etalon.
Chemical analysis:
Calibration of spectrophotometer by Authorized Service every 2 years.
Calibration of spectrophotometer(6 points) at least one per 2 years.
Interlaboratory Comparison EMEP (1x / 1year).
Regular use of control sample, prepaired from RM, traceable to SRM, NIST.
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| Scale and calibration(treasability) |
: |
Sampling:
Traceability of calibration etalons to national and international etalons was checked by Slovenian Acreditation, the member of European co-operation for Acreditation.
Chemical analysis:
RM in use is traceable to SRM, NIST
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| Data Processing |
| Measurement unit |
: |
ppb |
| Data processing |
: |
Daily data is calculated from quantity of NO2 determined in 24h extract from the glass filter impregnated with sodium iodide (NaI) and sodium hydroxide (NaOH), divided with quantity of air (at 293°K) pumped through glass filter in sampling period, to get concentration of NO2 in µg/m3. To get ppm units, the data in µg/m3 NO2 is divided with factor 1,91.
All 24-hour data is controlled (EMEP EDC program) and flagged. Valid and invalid data is reported. Flags indicate the validity of data.
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| Processing for averaging |
: |
Processing for Monthly Data:
Monthly NO2 data data are generated by arithmetic means from the valid daily data. |
| Data flag |
: |
The list of EMEP data flags is used. List of flags is available on EMEP homepage / CCC / Data submission / List of flags used in EMEP data base (http://www.nilu.no/projects/ccc/submission.html). |
| Data remarks |
: |
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| Other Information |
| Scientific aim |
: |
To provide data for research and study to reveal long term trends. |
| Reference |
: |
EMEP manual for sampling and chemical analysis (EMEP/CCC-Report 1/95, Reference: O-7726, Norwegian Institute for Air Research, Date: March 1996, Revision: November 2001) (http://www.nilu.no/projects/ccc/manual/index.html). |
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| submitted by Slovenian Environment Agency |
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