Levels of mercury (Hg), Cadmium (Cd) and Zinc (Zn) were studied in five major roads in Uyo metropolis. Result of total Hg ranged from 0.05mgkg-1 in Calabar-Itu Road to 0.675mgkg-1 in 4 Lanes. Total Cd varied from 0.60mgkg-1 to 1.90mgkg-1.While total Zn ranged from 3.750mgkg-1 to 6.170mgkg-1. Available Hg concentration was low (0.008mgkg-1 to 0.05mgkg-1) and value was within permissible limit. Available Cd ranged from 0.035mgkg-1 to 0.100mgkg-1 with a mean of 6.24mgkg-1. while available Zn (0.335mgkg-1 to 1.503mgkg-1) was highest in Cal-Itu Road. On the average, 4 Lane had the highest while Cal-Itu Road had the least concentrations of the studied elements. The wide variability of the elemental concentrations across the studied area is attributed to greater variability of input concentration from a variety of sources from where they are transported to respective locations.
1.1 Gutter sediment within urban roads represents a collection of multiplied contributing source of pollution including automobile emission, urban infrastructure, degradation and erosion, and other particulate non-point sources from short and long-range atmospheric deposition (Vermelte et al, 1987, 1991: Sutherland 2003). Harmful substances emitted by exhaust and wear from vehicles are deposited and accumulated daily on road gutters and surrounding soils together with primary and secondary particles from other anthropogenic (demolitions/ construction industrial activities etc) and natural sources (short and long range transport of suspended sediments). These dispositions on roads are commonly referred to as road/gutter deposited sediments (RDS/GDS) San-Miguel et al. ( 2002).
The natural fraction of gutter deposited sediments consist of materials, plant materials and atmospheric depositions (Rogge et al, 1993). The anthropogenic fraction contains high concentrations of heavy metals originating from brake linings, the combustion of fuels and the wear and tear of pavement’s as well as tires and vehicle body (Davis et al., 2001; San-Miguel et al., 2002) and also industrial activities, municipal solid waste incineration and metals smelting.