Samples of PM 2.5 were collected sequentially for 24 hours during the last week of September to mid February 2009-10 at three locations representing residential (R), commercial (C) and industrial (I) sites in Nagpur city to determine their chemical composition and estimations of the sources contributing to them. Two receptor models were used for the source apportionment viz. enrichment factors (EF) to differentiate crustal and non-crustal sources, whereas chemical mass balance (CMB 8.2) was used to identify and quantify the major sources contributing to PM 2.5 .The Findings of EF showed the anthropogenic origin of Cd, Ni, Pb, Cu, Fe and Zn, whereas Ba, Cr, Mg, Mn, and Si were contributed from crustal sources. On the other hand, results of CMB using source profiles developed in India for nonvehicular and vehicular sources revealed that vehicular emissions were major contributing sources 57, 62 and 65%; followed by secondary inorganic aerosol 16, 12, 16%; biomass burning 15, 11, 9% and then by re-suspended dust 6,10, 7% at R, C and I sites, respectively. This study showed that while the sources at all three sites were mostly consistent, the percent contributions of these varied among the sites as per the intensity of ongoing activities at the receptor sites.

Influence of burning of fireworks on particle size distribution of PM(10) 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 PM(10) and Ba were observed during diwali as compared to days before diwali and other activities. PM(10) 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 PM(10) 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.

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A workshop on analytical quality control (AQC) of ambient air quality measurement methods for nitrogen dioxide (NO(2)) and sulphur dioxide (SO(2)) was conducted by Central Pollution Control Board (CPCB) for officials involved in National Ambient Air Quality Monitoring (NAAQM) in India. Concentrations of NO(2) and SO(2) 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 NO(2) and SO(2) 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 NO(2) and SO(2) 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 SO(2) 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 NO(2) and SO(2) at high concentration levels (alpha 0.05) and for SO(2) at both the levels (alpha 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 NO(2) and SO(2) in ambient air.

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Particulate size distribution of PM(10) and associated trace metal concentrations has been carried out in residential cum commercial area of Mahal at Nagpur city. Sampling for size fraction of particulate matter was performed during winter season using eight-stage cascade impactor with a pre-separator and toxic metals were analyzed using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The average concentration of PM(10) and fine particulate matter (effective cut of aerodynamic diameter ≤2.2 μm) was found to be 300 and 136.7 μg/m(3), respectively which was exceeding limit of Central Pollution Control Board. Maximum mass concentration of 41 μg/m(3) in size range of 9.0-10.0 μm and minimum mass concentration of 19 μg/m(3) in size range 2.2-3.3 μm was observed. Metals (Sr, Ni and Zn) were found to large proportions in below 0.7 μm particle size and could therefore pass directly into the alveoli region of human respiratory system. Factor analysis results indicated combustion and vehicular emission as the dominant source in fine mode and resuspended dust was dominant in medium mode while crustal along with vehicular source was major in coarse mode of particulate matter.

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