*2.1. Sampling Sites*

Soil samples were collected from six different sites in the city of Lisbon. Lisbon is the capital city of Portugal with about half a million inhabitants and 2–2.5 millions of commuters every day. Since industrial activity is almost inexistent in the city, the main anthropogenic source of air and soil pollution relies on vehicle traffic.

The sampling sites (Figure 1) were chosen taking as criteria the level of automotive traffic, the population density, and the topology of the site. The existence of a high population density is important in order to reduce the health risk due to soil pollution, in particular from its use in urban gardens or parks. The topology of the site is critical to interpret whether the dispersion of the pollutants is favored in each location.

**Figure 1.** Soil sampling sites in the city of Lisbon.

The characteristics of each location are: CE1—City Entrance in Belém (GPS: 38.69562, –9.19930)—one of the city entrances with an open topology and characterized by a high traffic intensity as well as a high population density; CE2—City Entrance in Calçada de Carriche (38.72653, –9.14992)—another city entrance, with a valley topology and a steep slope of entrance in the city. It is also characterized by a high traffic intensity and a high population density; UH—Urban Highway of Segunda Circular (38.75796, –9.16339)–a city circular road with urban highway characteristics. Moreover, it is characterized by an open topology and a very high traffic intensity; CC—City Center at Marquês de Pombal (38.78163, –9.16551)—it has a valley topology and is a high traffic, as well as a high population density site; RA—Residential Area (38.75741, –9.11784)—in the neighborhood of Olivais with open topology and a low traffic intensity; CP—City Park of Monsanto (38.73387, –9.17786)—a small sloping mountain and the major city green park. It has a low traffic intensity and no residential population or buildings.
