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Khaparde VV Pipalatkar PP Pustode T Rao CV Gajghate DG 《Environmental monitoring and assessment》2012,184(2):903-911
Influence of burning of fireworks on particle size distribution of PM10 and associated barium (Ba) were studied at a congested residential cum commercial area of Nagpur city, India. Sampling was
carried out by cascade impactor having 50% cut-off aerodynamic diameters of <10, 9, 5.8, 4.7, 3.3, 2.1, 1.1, 0.7, and <0.4 μm,
2 days before diwali, during diwali, celebrations of marriage functions, and New Year’s Eve. Noticeably, increased levels
of PM10 and Ba were observed during diwali as compared to days before diwali and other activities. PM10 levels were increased by four to nine times whereas Ba levels were increased by eight to 20 times higher in alveolar region,
when compared with the levels observed before diwali. Probability of deposition of Ba mass in alveolar region varied between
14 and 27 ng/h with higher deposition when the burning of fireworks activity was lower near the site. Trimodal distribution
of Ba was observed on the first 2 days of diwali at 0.4–2.1, 2.1–4.7, and 4.7 to less than PM10 micrometer range. While on the third day, it appeared bimodal with 70% contribution in coarse fraction whereas on the fourth
day, distribution appeared unimodal with 66% contribution in alveolar region (<0.4–1.1 μm). Distribution of Ba varied with
respect to particle size, in accordance with the intensity of the fireworks used on different days and distance between the
burning of firecrackers from the monitoring site. 相似文献
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Khaparde VV 《Environmental monitoring and assessment》2006,116(1-3):217-231
A workshop on analytical quality control (AQC) of ambient air quality measurement methods for nitrogen dioxide (NO2) and sulphur dioxide (SO2) was conducted by Central Pollution Control Board (CPCB) for officials involved in National Ambient Air Quality Monitoring
(NAAQM) in India. Concentrations of NO2 and SO2 were generated by dynamic dilution system under laboratory conditions at low and high levels and measured using static dilution
system and wet chemical methods laid down by CPCB under section 16(2)(h) of the air act 1981. CPCB provided the measured values
as reference values for comparing the means obtained by the officials participated from thirteen organizations. A tolerance
limit of ±15% of the reference values was specified to accept the results. Generated concentrations, which were unknown to
the participants, were measured using gaseous sampling assembly (Envirotech APM 411, New Delhi, India), and wet chemical methods
laid down by CPCB i.e. the same methodology which is used by the organizations to generate the data of NO2 and SO2 in ambient air. Simultaneously, concentrations were checked by CPCB using automatic analyzers as a check on reference concentration.
It is observed that results of automatic analyzers for NO2 and SO2 were within a tolerance of ±5% with %RSD below 3. On the other hand, results of most of the participants showed variability
in the measurements with %RSD ranging between ±0.8 and ±88.6 and exceedences of means from the tolerance limit with bias ranging
between 1.4 and −59%. To check the cause of high variability in the measurements obtained under identical conditions, duplicate
sampling was performed by one of the participants for SO2 at low concentration level. In this study, results of wet chemical methods, automatic analyzers and results of duplicate
sampling are analysed statistically to assess the cause of high variability in the measurements. Analysis of t-test and analysis of variance (ANOVA) showed highly significant results for NO2 and SO2 at high concentration levels (α 0.05) and for SO2 at both the levels (α 0.01) respectively indicating some bias is existing either in the sampling or in analytical technique.
Duplicate sampling performed to check precision in parallel measurements showed high %RSD indicating the presence of systematic
error in sampling technique as the same calibration factor (CF) was used to measure the concentration of duplicate samples.
Statistical analysis of flow rates of duplicate sampling showed that the sampling assembly could not maintain the constant
flow rate within the ±10% with that measured at the start of the sampling. This resulted in high %RSD and deviation from the
reference values for the results of most of the participants, even after accepting ±15% tolerance limit. There is a need to
improve and evaluate this gaseous sample collection device under laboratory conditions to generate reliable database of NO2 and SO2 in ambient air. 相似文献
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