Environmental Engineering Reference
In-Depth Information
Fig. 6
Graphical representation of Zn
concentration values in surroundings of
the guard rail. GR 1: soil sample just
under the guard rail. GR 2 and GR 3:
soil samples moving away the guard rail
Finally, soil samples under the guard rail contain very high concentration of Zn
values. Three different samples were collected nearby it. The one just under the
guard rail (GR 1) points out the highest value for Zn concentration among all the
soil samples analyzed, and shows a very strong decreasing gradient as they move
away from it in very few meters (GR 2 and GR 3) (Fig.
6
).
Conclusions
ICP/MS semi-quantitative analysis of the soil samples allows the fast determination
of most soil elements as a first tool for evaluating the impacted area. A first list of
metals that could be related to road traffic was identified by means of the chemo-
metric analysis of the obtained semi-quantitative results ICP/MS: Cd, Cr, Cu, Hf,
Mo, Nb, Ni, Pb, Sb, Sn, Sr, Zn and Zr. The study area was reduced. The secondary
road appears to be much more polluted by the traffic emissions than the highway.
TRE in the west roadside appear at higher concentrations than the rest of sampling
areas, included the control soils, probably due to a longer-term accumulation in the
first one as well as its topographical characteristics that would lead to the concen-
tration of atmospheric particles in a smaller area (because of the presence of a road
cut). The east roadside in the secondary road as well as soils further away from the
highway appears not to be affected by the road traffic, and it shows similar metal
concentration values to control samples.
Soil samples from diverse origins could be differentiated in basis of their rare
earth elements and alkaline metal concentrations. It was concluded that soils from
both roadsides in the secondary road have different source, as well as highway
soils. West roadside seems to be original land, whereas the highway land is possible
to be a filling, as for soil samples further away, at a distance of 9 m from the road
seem to be original land too. Finally, east roadside has another different source, as
the presence of a road cut suggests it.
Two groups of metals appeared in the correlation analysis suggest a different
emission source for both of them. Hf and Zr are associated to catalytic converters in
automobiles and they enter in the environment by atmospheric deposition of the
exhaust fumes, whereas Cd, Cr, Cu, Mo, Ni, Pb, Sb, Sn and Zn have different
