Diurnal Study of VOCs in Raipur, Chhattisgarh

 

Dr. Saroj Sharma

Govt. Kamla Devi Girls College Rajnandgaon C.G.

*Corresponding Author Email: ssharmagr8@gmail.com

  

ABSTRACT:

Volatile organic compounds (VOCs) play an important role in the generation of O3 and other reactive chemicals in the atmosphere. Anthropogenic emission of VOCs has greatly increased due to growing consumption of fossil fuels and related activities. The concentration of 12 light, C2-C8 VOCs in ambient air of the most industrialized area, Raipur, was measured. The sampling frequency was once in a week at sites: Raipur, (R. S. University campus), for one year, April, 2006 - March, 2007. For diuranal study per hour samples were collected. Twelve VOCs species i.e. C2H2, C2H4, C2H6, C3H6, C3H8, i-C4H10, n-C4H10, i-C5H12, n-C5H12, C6H6, CH3.C6H5 and CH3.C6H4.CH3 were monitored by technique: gas chromatography equipped with FID and PID detector and the purge and trap probe were used The mass distribution of ∑12VOCs at site: Raipur, was ranged 48.7 - 171, µg m-3 with mean value of 102.2  ± 8.6, 135. µg m-3,. Among twelve VOCs, three species: C3H8, C4H10 and C5H12 exhibited the highest mass distribution, and accounted > 55% fraction of the total VOCs.

 

 

 

INTRODUCTION:

Volatile Organic Compounds (VOCs) are organic chemicals that easily vaporize at room temperature and major group of air pollutants which play critical role in atmospheric chemistry. It contributes to toxic oxidants which are harmful to ecosystem, human health and atmosphere due to their role as precursors of ozone, photochemical smog, etc.  The main emission sources of VOCs reported are gasoline, coal and biomass burning, cooking, smoking, paints, varnishes, solvents, cleaning chemicals, adhesive and fuel oil, etc. Methane an extremely efficient  greenhouse gas contributes to enhanced global warming whereas other VOCs are also significant greenhouse gases (14), the aromatic compounds, i.e. benzene, toluene, xylene, 1,3-butadiene, etc. are suspected to be toxic compounds .

 

Various investigations were carried out to obtain characteristics and influence of pollutants (VOCs) on ozone episode in India) however, limited measurement available of seasonal and diurnal variation of hydrocarbons.

 

In the proposed work, an attempt was made to monitor the diurnal mass distribution of 12 light, C2-C8 VOCs in ambient air of Raipur (R. S. University campus), (April, 2006 - March, 2007.)

 

EXPERIMENTAL:

Study area

The Raipur region of the country was selected for the proposed investigation due to running of industries and huge coal burning

Sample collection

 

The air samples were collected from sites: Pt. Ravishankar Shukla University, Raipur. A Reena 200-A (France) air sampler was used for collection of the air sample and collected into 5-litre tedlar bag.

 

Fig 1: Representation of sampling site Raipur (Pt. R.S. University Campus)

 

RESULTS AND DISCUSSION:

Diurnal variation of VOCs

The diurnal variation of 12 VOCs i.e. C2H6, C2H4, C3H8, C3H6, i-C4H10, C2H2, n-C4H10, i-C5H12, n-C5H12, C6H6, CH3.C6H5 and CH3.C6H4.CH3 was investigated on 5th April, 2006. A strong variation in the mass concentration of the VOCs was observed, The presented data are the mean values of TVOCs observed on 5th April 2006. Figure 1.2. The average TVOCs mass concentration is ranged from 2.8 - 9.3 µg m-3 with mean value (n = 12) of 5.9 ± 2.4 µg m-3. The mean patterns show pronounced diurnal variability in all VOCs species. Unlike Raipur, the diurnal variability in Osaka (Japan) shows large morning peaks apart from completely different diurnal patterns in C2-C5 VOCs .

 

Fig: 1.2: Diurnal variation of  average TVOCs observed during the 5th April 2006 at Raipur.

 

CONCLUSION:

The mass concentration of the VOCs in the ambient air is strongly dependent upon the frequency and strength of mobile and stagnant sources.  Among 12 VOCs monitored, the n-C4H10 exhibited the highest mass concentration in the ambient air . During the night time concentration was highest and day time in the presence of  sunlight VOCs form photo chemical smog so show lowest concentration.

 

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Received on 12.02.2014                             Accepted on 10.03.2014        

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Research J. Engineering and Tech. 5(1): Jan.-Mar. 2014 page 07-08