Abstract:
Horton Plains National Park (HPNP) is an ecologically sensitive area; therefore,
utilization of such an area should involve a high consideration on environmental
safeguarding. Visitor statistics of HPNP clearly indicate that the number of visitors is in
increasing trend and parallel increment of vehicles entering the park each year. But, the
park does not have any regular air quality management system in place yet and the past
measurements of air pollution have been done on an ad hoc basis. In this context, the
necessity to carry out a study to determine current levels of Nitrogen Dioxide (NO2) and
Sulfur Dioxide (SO2) concentrations in ambient air in the National Park and initiation of
an ambient air quality database was identified. This research work describes the
determination of levels of NO2 and SO2 at HPNP using of passive sampling technique.
Ambient levels of these pollutants were monitored in twelve sites including two
background sites from 9th November 2016 to 31st January 2017 at two weeks’
intervals.
There was a significant strong positive relationship between the results obtained by
duplicate sampling of passive sampling device. Highest variation of both NO2 and SO2
was observed in the Ohiya road ranging from 1.02 μg/m3 to 6.41 μg/m3 and 4.75 μg/m3
to 21.14 μg/m3 respectively. The highest two weeks mean concentrations of NO2 and
SO2 were recorded at the Car park and Pattipola road with values of 3.67 ± 1.92 μg/m3
and 17.68 ± 4.58 μg/m3 respectively. The lowest two weeks mean concentrations of NO2
and SO2 were recorded in undisturbed forest site (background site) and forest die back
site with values of 0.95 μg/m3 ± 0.38 and 2.91 ± 1.56 μg/m3 respectively. Ambient NO2
concentrations of 6.41 μg/m3 and 0.32 μg/m3 were recorded as Highest and lowest
levels for the entire data collection period respectively for Ohiya road and background
site. Highest and lowest SO2 levels of 25 μg/m3 and 1.32 μg/m3 were obtained for the
Pattipola road site and the background site. Results indicate that the measured air
pollutant levels in HPNP currently are very low and do not exceeded the Sri Lankan
ambient air quality standards. Furthermore, correlations of ambient pollutant levels
(NO2, SO2) with visitor presence, rainfall, temperature and relative humidity were also
investigated in this study.
