كليدواژه :
urban environment , traffic demand model , Lead and cadmium determination , traffic pollution , roadside soil pollution
چكيده فارسي :
Lead and cadmium are heavy metal pollutants released by vehicles which
are propagated into the urban environment by traffic flow. To study
roadside soil pollution and to determine the traffic parameters affecting
levels of read and cadmium in soil, Isfahan was selected for a case study. In
this city, soil samples were collected from 13 roadside sites and traffic
parameters were determined. The traffic parameters studied include total
traffic volume, total traffic volume to road oriented width, total traffic
volume total traffic capacity, speed, and aspect ratio. Average lead and
cadmium concentration in soil at distances from 0 to 50 meters from the
road edge were found to be higher than background values, thus failing to
meet maximum acceptable agricultural soil standards. The regression
analysis of concentrations in stream soils versus selected traffic parameters
showed that the total traffic volume was the parameter with the highest
impact on soil metal content. Also, it was observed that lead and cadmium
concentration (as dependent variables) decreased logarithmically with
increasing distance (as one of the independent variables) while each of the
lead and cadmium concentration increased linearly and exponentially,
respectively, with increasing total traffic volume (as another independent
variable). The regression models developed in this study can be used for
predicting lead and cadmium levels in roadside soil in terms of distance
from road edge and total traffic volume. The results obtained obtained from
this study may be used in urban traffic control, transportation management,
urban design and architecture, and urban land use planning.
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