Air Pollution Mapping and Quality Assessment Study at an Urban Area Tirupati Using GIS - Management of Natural Resources in a Changing Environment - page 240

Table 1 Sampling points of
the study area

S. No. Location name Description

1 Thummalagunta (TG) Rural

2 SVU Campus (SVUC) Educational

3 Bhavani Nagar (BN) Residential

4 Gandhi Road (GR) Traffi c

5 Ramanuja Circle (RC) Traffi c

6 Shetti Palle (SP) Industrial

with a frequency, once in a week for 24-h monitoring using High Volume Sampler
(Envirotech, APM 415). Ion chromatography was employed to analyze anions and
cations. Spatial distribution maps were prepared for air quality parameters (F, Cl,
NO 3 , SO 4 , Na, K, Ca, Mg, NH 4 ) and for TSP classifi ed map by doing interpolation
technique of inverse distance weighted (IDW) method in Arc-GIS spatial analyst
tools.

Results and Discussion

Spatial Distribution of Ions

The mean ionic concentrations of TSP are presented in Table 2 . The obtained mass
of TSP is between 69.34 ± 14.02 (SVUC) and 178.31 ± 13.14

g/m 3 (SP). Highest
mass loading of TSP is due to the presence of small scale industries at sampling
point SP. In areas such as TG, GR, RC and BN the mass of TSP observed were
97.25 ± 7.94, 110.16 ± 13.86, 120.23 ± 18.49 and 134.42 ± 10.06

μ

g/m 3 respectively.
Among all ions SO 4 reported maximum concentration, whereas lowest is F. The
ionic concentrations of TSP are in the following order SO 4 > Na > NO 3 > Cl > Ca > K >
NH 4 > Mg > F (Table 2 ). Spatial distribution of SO 4 is shown in Fig. 2 . The concen-
tration of SO 4 varies from east to the west direction. Lowest concentration is seen in
the centre of the map (RC), whereas highest concentration pocket is seen in the
western area of SVUC. Highest concentrations may be soil derived from the
cultivated land near the SVUC and also gas-phase SO 2 on the wet surface of basic
soil particles. Figure 3 shows the spatial distribution of NO 3 , and is found to be
distributed over the east to the western region of the study area. Small pocket of high
concentration is seen in the northwest region (BN). Similarly, high concentrations
are seen in the western regions, SVUC and TG. Higher concentrations may be
attributed to soil dust from cultivated lands and also NO 3 may be formed by the
absorption and subsequent reaction of NO 2 on the soil aerosol droplet or by the dis-
solution of gaseous HNO 3 . Dairy farm with livestock of around 500 herds of cattle,
located near the western region of the study area, this may act as major source of
ammonia gas and would be favoured for the formation of NH 4 NO 3 .
Spatial distribution of NH 4 is shown in Fig. 4 . The concentration of NH 4 is con-
sistence throughout the study area. However, low concentration pockets are located

μ