Dry depostion monitoring

Transcription

1 Dry depostion monitoring Pojanie Khummongkol Fundamental items of dry deposition Monitoring sites Monitoring frequency Priority of chemical species of dry deposition 1

2 Monitoring sites Should be done at the same site used for wet deposition monitoring Total deposition = wet + dry Monitoring frequency 1. Automatic Monitor: hourly 2. Filter Pack Monitor: Expected Every Week 12 months 1 year acceptable Daily 12 months 1 year Biweekly 12months 1 year 2

3 Priority chemical species First priority: SO 2, O 3, NO, NO 2 (Urban) Particulate mass conc. Second priority: NO 2 (rural and remote) HNO 3, NH 3, Particulates (SO 2-4, NO 3-, NH 4+, and Ca 2+ ) Automatic Monitors Monitor: SO 2, NO, NO 2 (urban), O 3, and PM Methods: SO 2 NOx O 3 PM 2.5 Ultraviolet fluorescent (UVF) Chemiluminescence detection (CLD) Ultraviolet photometry (UVP) Dichotomous sampler β-ray absorption TOEM 3

4 SO 2 Monitor SO 2 + hν 1 SO 2 * (1) SO * 2 SO 2 + hν 2 (2) SO * 2 SO + O (3) SO 2* +M SO 2 +M* (4) NO, NO 2 monitor (Chemiluminescence) NO+O 3 NO 2 *+O 2 (1) NO 2 * NO 2 +hν (2) NO 2 *+M NO 2 +M* (3) 4

5 Ultraviolet Photometric Method for O 3 Measure absorbing quantity of ultraviolet rays near 254 nm by ozone Beer-Lambert Law: T Io O3 (ppm) = x x ln kl P 273 I k = absorption coefficient = 124 cm -1 atm -1 I = transmitted light quantity I o = incident light quantity L = cell length, cm T = cell outlet temperature P = cell outlet pressure PM 2.5, PM 10 Monitor Dichotomous sampler Sample air from aerosol inlet 5

6 β-ray absorption Absorption rate of β-ray increases in proportion to the mass of the substance when its quality remains constant and the ray at a low energy level irradiated the substance. I = I o µ exp X m m X m = 1 µ m Io ln I I = β-ray intensity transmitted through filter and particulate, I o = β-ray intensity transmitted only through filter, µ m = mass absorption coefficient (cm 2 /g), X m = mass of particulate matter (g/cm 2 ) TOEM Method 6

7 Passive Sampler To monitor gases: SO 2, NO 2, O 3 and NH 3 Gases Absorbent Component analyzed Analyzer SO 2 NaOH Sulphate IC NO 2 Ethylene glycol Nitrite SP with FIA HN 3 Citric acid Amonium IC IC - Ion Chromatography SP with FIA - Spectrophotometry Using flow injection analysis 7

8 Fick s Law: M = D A L Ct M = total mass of gas transferred (ng) D = diffusion coefficient (m 2 /s) L = Length of the diffusion path (m) A = cross sectional area of diffusion path (m 2 ) C = ambient concentration of contaminant (ng/m 3 ) t = time of exposure to contaminated air (s) D = 1.32x10-5 m 2 /s and A/L = 41.2/m for CSIRO sampler Filter Pack Method in EANET To monitor: Gases- SO 2, HNO 3, HCl, NH 3 Particulate Components SO 2-4, NO 3-, Cl -, Na +, K +, Ca 2+, Mg 2+, NH + 4 8

9 Sampling height- 3 m above ground Obstacles nearby Then- set up higher than 3 m or above the obstacles Flow Rate- 1 L/min If Low conc.- use 2 L/min Daily samplinguse 15 L/min System 1- for high altitute (mountain) Flow meter Gas Volume meter 9

10 Stage Reaction Collected species Filtration Neutralization by 6%K 2 CO 3 +2%glycerin in water Aerosol Adsorption HNO 3 Partial SO 2, HCl Neutralization by collected acid gases Partial NH 3 SO 2, HCl Neutralization by 5%H 3 PO 4 +2%glycerine in CH 3 OH NH 3 Preparation of Filter Pack Handle filters and extraction solutions in the lab. only under clean condition Always use disposable plastic gloves and tweezers when handling filters Always seal up the filters, especially impregnated one to avoid the contamination 10

11 NILU filter holder (4-stage open face) Mounting a filter on a stage Tightening a stage by And Exclusive torque Sealed filter case Sealed filter holder Extraction and Chemical Analysis Extraction - every month Chemical analysis - every month Chemical analysis - carried out as soon as possible after the extractions The extraction samples shaking on a shaker or ultrasonic bath for 20 min Extraction and Chemical analysis of blank filter carried out at the same time 11

12 Analyzed species and solvent for each stage Stage Species Solvent 1 SO 2-4, NO 3-, Cl -, Na +, K +, Ca 2+,NH 4+, 2 SO 2-4, NO 3-, Cl -, NH + 4 Deionized water Deionized water 3 SO 2-4, Cl % H 2 O 2 4 NH + 4 Deionized water Analyzer: Ion chromatography (IC) Ion Chromatography Report 12

13 Treatment of Blank Determine a blank value as median of 5 analytical results of blank filters Median value Chemical analysis of samples and blanks should be done each month When blank value > sample value non-detected (N.D.) If samples are obviously contaminated unrecorded data Samplings are stopped accidentally sample rejected Artifacts of filter pack Increase of temperature during sampling period causes particulate collected on filter, ie. NH 4 NO 3, NH 4 Cl and NaCl to volatilize to gases, ie. NH 3, HNO 3, and HCl, and recollected on following filters. 13

14 Artifact of filter pack method Artifacts of HNO 3 NH 4 NO 3 (P) NH 3 (G) + NHO 3 (G) NH 4 NO 3 (P) + H 2 (P) NH 4 (P) + HNO 3 (G) NaNO 3 (P) + H 2 (P) NaH (P) + HNO 3 (G) Artifacts of NH 3 NH 4 NO 3 (P) NH 3 (G) + NHO 3 (G) NH 4 Cl(P) NH 3 (G) + HCl(G) H 2 (P) + NH 3 (G) NH 4 H (P) Artifacts of HCl NaCl(P) + HNO 3 (G) HCl(G) + NaNO 3 (P) 2NaCl(P) + H 2 2HCl(G) + Na 2 (P) NH 4 Cl(P) HCl(G) + NH 3 (G) NH 4 H (P) + NH 3 (G) (NH 4 ) 2 (P) Calculation of Results C 10 3 α = ; M = α(net C Sol V ) V Sol net C Sol = C Sol, Sample C Sol, Blank C : concentration in the air (nmol/m 3 ) net C Sol : net concentration in the solution (mg/l) V Sol : volume of the solution (ml) V : volume of the sampling air corrected at 20 o C, 1 atm (m 3 ) M : molecular weight 14

15 Determination of Concentrations Species M Equation Aerosol 2- NO 3 - Cl - Na + K +, Mg 2+ Ca 2+ NH = α(net C C Sol, F0 V ) V SO (SO 2-4 ) C = α ( net C + Sol, F net CSol, F )( VSol / V ) 1 2 HNO (NO ( )( ) - 3 ) C = α net CSol, F VSol / V 1 HCl (Cl C = α ( net C + Sol, F net CSol, F )( VSol / V ) - ) 1 2 NH (NH 4 + ) C = α ( net C + net C )( V / V ) 1 Sol, F Sol, F3 Sol Sol Form (Dry) January 2003 Calculation of air concentration (Filter Pack) Site name : Chiangmai Site Classification : Rural Name of Laboratory : KMUTT Sample no. Jan-03 particle start End Ave. temperature volume correction Date Time Date Time C m3 m3 30/12/2002 9:00 6/1/2003 9: NO 3 - Cl - NH 4 + Na + K + Mg 2+ Ca 2+ F0(mg/l) Sample Blank Net conc. (nmol/m 3 ) gas 2- - NO 3 Cl - + NH 4 Na + K + Mg 2+ Ca 2+ F1(mg/l) Sample Blank Net F2(mg/l) Sample Blank Net F3(mg/l) Sample Blank Net conc. (nmol/m 3 ) SO 2 HNO 3 HCl NH Name of reporter : Sugrit Buddhirakkul = α(net C C Sol, F0 ( net C netc )( V / V ) C = α + Sol,F1 M = 18 V ) V Sol,F3 Sol Sol 15

16 Data Report Form (Dry) Site name : Chiangmai Results of air concentration analysis (Filter Pack) Site Classification : Rural Name of Laboratory : KMUTT Name of reporter : Sugrit Buddhirakkul Unit : nmol/m 3 Sample Sampling period Gas Particle 2- no. SO 2 HNO 3 HCl NH 3 Cl - + Start End NH 4 Na + K + Mg 2+ Ca 2+ Date Time Date Time /12/ /12/ /1/ /2/ /2/ /3/ /3/ /3/ /4/ /5/ /6/ /6/ /6/ /7/ /8/ /8/ /9/ /9/ NO 3 - Thank you 16