Effects of Atmospheric Salt Deposition on Highway Runoff Characteristics – A Pilot Case Study - Highway and Urban Environment - page 213

Fig. 3 Photo and scheme of monitoring system at the A25 site
followed in accordance with international standards procedures [4] , based on an
adequate Quality Assurance and Quality Control plan establish for G-Terra Project.
Among other quality parameters were: COD, TOC, oil and grease, salinity and chlo-
rides. Other common parameters determined in the runoff water samples are: tem-
perature, pH, conductivity, turbidity, Total Suspended Solids (TSS), total hardness,
Total Kjeldahl Nitrogen (TKN), total phosphorus, Biochemical Oxygen Demand
(BOD 5 ), total Fe, total Zn, total Cu, total Pb, total Cd and total Cr.
Results and Discussion
The results concerning the first 2008 monitoring period at the A25 pilot case study
are summarized in Table 4 , and the salt deposition rate is presented in Table 5 .
These preliminary results are similar to the other highway runoff studies in costal
zones made in Portugal. It is common, namely the high levels of salinity, organic
matter and related parameters, as the comparison between Tables 4 and 1 can con-
firm. It is also observed higher levels for nitrogen and phosphorus.
Considering the A25 case (see Tables 3 and 4 ) the levels of conductivity, salinity,
chlorides and COD, although of similar magnitude, show higher concentrations in
2008. The 2008 Average Daily Traffic (ADT) at A25 (29350 vehicles in May 2008)
compared to the value for 2003 (27,000 vehicles), may explain the higher values for
the parameters related to traffic sources. Nevertheless, it is not expected that salinity
and parameters such as nitrogen and phosphorus are associated with the ADT.