Ileperuma, O.A., Priyantha, N., Chandrajith, R., Perera, A., Yatigammana, S.K. and Wijesundara, C.
(editors) (2013): Symposium Proceedings, Second International Symposium on Water Quality and
Human Health: Challenges Ahead, 15-16 March, PGIS, Peradeniya, Sri Lanka
SHORT RANGE TEMPORAL TRENDS OF ATMOSPHERIC
DEPOSITION OF HEAVY METALS IN AN INDUSTRIALIZED AREA
IN SRI LANKA USING MOSS (Hyophila involuta) AS A
BIOINDICATOR
H.P. Andaraarachchi and M.P. Deeyamulla*
Department of Chemistry, University of Kelaniya, Kelaniya, Sri Lanka.
Sri Lanka is a developing country and its urbanization and industrialization rate is
very high. Consequently, the atmosphere is being polluted and in order to control air
pollution, a systematic air pollution monitoring method is much required. As air
monitoring requires sophisticated, expensive equipment, it is essential to pay attention to
alternative cost-effective methods, such as biomonitoring, which is very suitable for the Sri
Lankan context. In this study, the atmospheric deposition of heavy metals was performed
quantitatively and trends were identified by analyzing moss (Hyophila involuta) as a
biomonitor.
Samples of H. involuta were collected at four sampling sites; Biyagama, Dalugama,
Sedawatte and Sapugaskanda. Kottawa rain forest was selected as the control. The moss
samples were analyzed for five heavy metals (Pb, Cu, Ni, Cr, and Cd) using atomic
absorption spectrophotometry (AAS). In order to investigate the correlations present
among the heavy metals, the Pearson correlations were tested using SPSS version 16.0 for
windows (SPSS Inc., USA). A significance level of 95% was the threshold for all tests.
The levels of metals retained by the mosses are expressed in µg/gmoss of the dry
weight of the moss sample. Concentrations of lead were found in the range of 74.45 –
355.55 µg/g in all four sampling sites. In general, lead concentration in mosses increased
from 2006 to 2011 in all sampling sites. There has been a gradual increase except the
sudden escalate of concentration in 2007 - 2008 time period. Concentrations of copper and
nickel increased throughout the period from 2006 to 2011 with ranges 31.92 - 127.50 µg/g
and 43.56 - 87.61 µg/g, respectively. All chromium measurements ranged from 103.68 –
232.07 µg/g. Cadmium concentrations gradually increased until 2008 followed by a drastic
decline and again a gradual increase.
The time series studies on moss concentrations indicate that generally each heavy
metal reveals a positive increasing trend with occasional fluctuations in all the sites in the
time period, 2006 - 2011. Lead and chromium showed significant increase, while nickel
and copper increased slightly. The gradual increasing trend had been disturbed by sudden
escalates in some elements, such as chromium and lead. High traffic congestion, oil
combustion in power plants and emissions of oil refinery and Lindel Industrial Zone were
identified as major anthropogenic sources. Statistically treated data illustrate that most of
the heavy metals reveal positive correlation with each other. Lead and chromium reveal a
homologous trend through the period and have a strong positive correlation relationship.
Nickel and copper also show a quite similar trend and have a moderate positive
association. Hence, there is a high probability that those heavy metals had been emitted by
the same sources. Therefore, such correlation studies will lead to the identification of the
pollution source, on which regulations could be implemented to minimize heavy metal air
pollution.
*
mpd@kln.ac.lk
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