Environmental Engineering Reference
In-Depth Information
Transport of Trace Metals by the Rainwater
Runoff in the Urban Catchment
of Guwahati, India
Upama Devi and Krishna G. Bhattacharyya
Introduction
Rapid urbanization and the consequent changes to urban traffi c characteristics such
as increased volume and congestion affect pollutant build-up on road surfaces as
well as the top layer of soil (Zhao et al.
2010
). In such cases, surface runoff accounts
for quite a considerable contribution to the total runoff from land, and carries with
it various contaminants from the road surfaces, built-up areas and other settlements
to the receiving waters. The runoff quality is also important in identifying the nature
of biogeochemical weathering processes (Skidmore et al.
2004
) and in characteriz-
ing the evolution of the drainage system (Tranter et al.
1996
). This has necessitated
the study of basic qualities and characteristics of organic or inorganic contaminants
in the rainwater runoff all over the world (Monticelli et al.
2004
; Wei et al.
2010
).
Metals in water and soil are involved in various sorption/desorption interactions,
redox reactions and chemical complexation with inorganic and organic ligands (Li
et al.
2000
; Violante et al.
2010
). The mobility and reactivity of metals in water and
soil affect their bioavailability, toxicity and distribution in the environment (Xue
and Yong
2007
). The solubility during precipitation and the redistribution into water
can alleviate their immobilisation by adsorption or complexing (Misra and
Chaturvedi
2007
).
Surface runoff is a signifi cant source of contaminants having tremendous impact
on the receiving aquatic environment and signifi cantly threatening nearby aquatic
habitats. The present study aims at the determination of diurnal changes in the phys-
ical and chemical properties of the runoff in the city of Guwahati including the trace
metal composition (Cd, Co, Cu, Mn, Ni, Pb and Zn) of the runoff in rainy seasons,
hence to correlate the metal concentrations with pH of the runoff measurements.
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