THE STUDY OF PHYSICOCHEMICAL CHARACTERISTICS IN TREE BARK OF ACACIA NILOTICA

The atmosphere might seem limitless but about 95% of the air is contaminated with first 12 -15 KM above the earth surface. The quality of the air gets deteriorated as a result of emissions of contaminants from all the mans activities including energy generation, manufacturing of goods and disposal of waste. Thus, to evaluate the effect of Air pollution on physicochemical characteristics a comparative study was undertaken in tree bark of Acacia nilotica L. with reference to different pollution area of Indore city. The result showed the variation in pH values which was recorded from 4.7 to 6.9. The lowest pH 5.0 was found at MPA and VPA in rainy season.Electrical conductivity was higher at all pollution areas. Highest value of electrical conductivity was recorded at VPA in rainy season 297.3 Âµmohs/cm2.While maximum % increase over LPA was seen in summer season at polluted area.

The atmosphere might seem limitless but about 95% of the air is contaminated with first 12 -15 KM above the earth surface. The quality of the air gets deteriorated as a result of emissions of contaminants from all the man's activities including energy generation, manufacturing of goods and disposal of waste. Thus, to evaluate the effect of Air pollution on physicochemical characteristics a comparative study was undertaken in tree bark of Acacia nilotica L. with reference to different pollution area of Indore city. The result showed the variation in pH values which was recorded from 4.7 to 6.9. The lowest pH 5.0 was found at MPA and VPA in rainy season.Electrical conductivity was higher at all pollution areas. Highest value of electrical conductivity was recorded at VPA in rainy season 297.3 µmohs/cm 2 .While maximum % increase over LPA was seen in summer season at polluted area.

…………………………………………………………………………………………………….... Introduction:-
In about last 150 years there occurred a fast deterioration of air, water and soil quality that ultimately resulted in the environmental crisis. Air pollutants once released from the source cannot be checked, treated or curtailed and thus travel long distances and may adversely affect plants, animals and human being. In India is at 7 th place among industrially developed countries. The population density increased around industrial and urban areas. For fast transportation number of auto vehicles also increased rapidly. All these have posed serious environmental problems. As a result, plant which is growing in its natural habitat is generally exposed to fluctuating levels of different pollutants. This level may exceed at any time to the level demonstrated to cause injury (Feder, 1973).In case of trees not only foliar surface but bark also absorb and accumulate the air pollutants. Bark is also exposed to environment for reaction with air pollutants as it provides a very large surface area next to leaves. In comparison to leaves where the surface is mostly smooth, in bark it is rough. Over the rough surface of bark chances of pollutants absorption and accumulation are more and may change bark characteristics like pH and electrical conductivity etc. The accumulation of air pollutants in bark is purely a physio-chemical process. The pollutants either passively accumulate on the surface of the bark or become absorbed through ion exchange processes in the outer parts of the dead cork layer ( 1040

Description of Experimental trees
Babul (Acacia niloticaL.) is useful in rural and urban area for various works.

Pollution areas
Pollution areas were selected on the basis of sources and nature of pollutants. Four areas were selected as mentioned below

Mixed pollution area (MPA)
This area is located in scheme No.78.

Vehicular Pollution area (VPA)
It is a part of Eastern ring road between Khajarana to Bengali square.

Industrial pollution area (IPA)
Sanwer Road, Industrial cluster situated on Ujjain road.

Low pollution area (LPA)
Ralamandal village. It is considered as reference area.

Materials and Methods:-
Bark was the main material for present work. Bark samples of experimental trees specie were collected in triplicate in all three seasons i.e. rainy (August), winter (December) and summer (April) in years 2015 and 2016. About 2 to 5 mm thick chips of bark were removed by sharp knife from all the directions around the tree at a height of 5-6 feet above the ground level and placed in a zipper poly bag. For uniformity trees of same height, canopy and main trunk size were selected at all polluted area. Bark samples of same tree species were also collected from low polluted area which serves as control or reference for comparison. The samples were brought in the laboratory for the further analysis.

Measurement of pH and Electrical conductivity
For measuring pH and conductivity aqueous extract was prepared. Bark samples were oven dried at 105º C for about 24 hours.5 grams of dried sample was grinded and soaked with 100ml of distilled water for 48 hours. The pH and electrical conductivity of the bark extract was determined following (Grodzinska, 1971) using Digital pH meter EI -112 and Digital conductivity EI-611 meter respectively.
In above data from table 1 and plate 1 it is evaluated that there is a change morphology, color,and Texture at all different polluted area. Presence of Lichen and Bryophytes can be seen at low polluted area which indicate low value of SO2 whereas in contrast to that deposition of pollutants can be seen at the vehicular polluted and Industrial polluted area indicate the presence of pollutants at high level. The bark extracts pH of Acacia nilotica growing at different pollution areas are presented in Tables 2 and 3. In general average pH values were found to be acidic mostly in rainy season at all pollution areas. Variation in pH values were recorded from 4.7 to 6.9. On as average the lowest pH 5.0 was found at MPA and VPA in rainy season. Although bark is a solid material & cannot have a pH, bark pH refers to the pH of unbuffered aqueous solution in contact with the bark (Kricke, 2002). The bark extract pH clearly indicates the nature of pollutants predominating in the study areas. Increased acidity of bark pH in vehicular polluted area can be linked with high sulphation rates. The predominance of SO2 accompanied with NOX in both vehicular and industrial polluted area and mixed polluted area appear to be responsible for the increasing acidic nature of the bark. In present study bark pH was recorded more acidic in rainy season in comparison to summer & winter. However, earlier work done by Joshi (1989) and Wagela (1998) reported more acidic nature of bark in summer & winter seasons at Indore. Hartel (1982) noticed that dry bark absorbed more SO2 than moist which results in more acidic nature of bark. Treshow (1971) also suggested that in dry season SO2 long lived and settled down slowly with aerosols and dust. Hence, it is possible that in summer season dry bark may have absorbed more SO 2 & NOx and thus become more acidic and this has appeared in rainy season. Electrical conductivity of barks extracts in Acacia nilotica at different pollution areas are presented in tables 3. In Acacia nilotica electrical conductivity was higher at all pollution areas. Highest value of electrical conductivity was recorded at VPA in rainy season 297.3 µmohs/cm2. Areawise and seasonally lower electrical conductivity was seen at LPA in summer season which was 126.0 µmohs/cm2. Likewise maximum % increase over LPA was seen in summer season at polluted area. Electrical conductivity is far more sensitive indicator of air pollution than bark pH. It changes even at 1041 small emission of SO2 which normally do not produce change in bark pH. As per Kreiner and Hartel (1986) the electrical conductivity of bark is mainly due to the presence of sulphate and other compounds.