Transport of Trace Metals by the Rainwater Runoff in the Urban Catchment of Guwahati, India - Management of Natural Resources in a Changing Environment - page 220

Table 2 Basic statistics of the metals (in mg/L) along with pH for the seven locations

Sampling sites
J Parameter N K M R U Z

Cadmium Min 0 0 0 0 0 0 0

Max 0.018 0.024 0.021 0.015 0.021 0.017 0.003

Mean 0.007 0.006 0.009 0.006 0.009 0.009 0.0005

Cobalt Min 0.032 0.02 0.029 0.033 0.054 0.02 0.113

Max 0.895 0.67 0.643 0.693 0.797 0.155 0.495

Mean 0.385 0.300 0.284 0.309 0.259 0.093 0.353

Copper Min 0 0.022 0 0 0 0.007 0.004

Max 0.446 0.614 0.258 0.283 0.019 0.078 0.043

Mean 0.127 0.190 0.094 0.121 0.002 0.028 0.018

Manganese Min 0 0 0.089 0 0 0.438 0.018

Max 1.022 0.54 0.765 0.599 0.642 0.672 0.082

Mean 0.313 0.232 0.359 0.281 0.317 0.558 0.043

Nickel Min 0 0.002 0.004 0.004 0.004 0.005 0.011

Max 0.178 0.185 0.08 0.107 0.17 0.032 0.208

Mean 0.038 0.059 0.027 0.030 0.066 0.018 0.088

Lead Min 0 0 0 0 0 0 0.079

Max 0.283 0.08 0.405 0.079 0.032 0.018 0.122

Mean 0.061 0.014 0.155 0.021 0.005 0.007 0.100

Zinc Min 0.007 0.014 0.024 0 0.031 0.107 0.079

Max 0.408 0.325 0.288 0.152 0.287 0.286 0.174

Mean 0.134 0.169 0.117 0.064 0.132 0.208 0.129

of the same to aquatic organisms. As acidity increases, most metals become water
soluble and thus, the runoff becomes more toxic (Wondie 2009 ).

Trace Metals

Urban soils and road-side soils are huge sink for the heavy elements and other pol-
lutants. The heavy metals as well as the inorganic and organic pollutants accumulate
in the top layer of soil. This may be contaminated to the runoff by heavy rainfall.
Mobility of the metals from sediment to runoff depends on the pH of the sediment
(Biljana and Natasa 2013 ). The basic statistics of the trace metals in the present
study are shown in Table 2 .
Signifi cant levels of trace metals are found in urban and highway runoffs from
many investigations. Among a variety of metals present in storm water, cadmium,
copper and lead are the most hazardous ones (Edwards et al. 1997 ) which appear to
be directly correlated to traffi c intensity on surfaces such as highways, streets, and
parking lots (Davis and Shokouhian 2001 ).
The trace metal contents in the present study are as follows: