Risk Assessment and time evolution of Total Petroleum Hydrocarbons (TPH) Fractions in soils

The analysis deals with soil samples taken from a central and well-known area of Santander (Spain), called "Jardines de Pereda". Besides being a very important zone which is often crossed by a lot of people and marginally also by means of transportation, the presence of three elements make it very interesting to our purposes:

a) A petrol station in the south western part of the site that represents a potential source of contamination from TPHs, mostly towards soil compartment.

b) A park with other recreative facilities almost all over the area, which is the main destination of the area, in such a way that people who most frequently utilize this area are the most susceptible ones to a potential contamination: children, old people, pregnant women or into motherhood…

c) An underground parking below the street level with an entrance on the west side of the area, representing an accessory facility, that potentially can expose a different target to a risk related to the presence of the petrol station: adult people that work there or that are parking users.

Because of this, in the context of a Risk Assessment from TPH fractions, there are two scenarios of exposure having different active exposure routes of exposure:

. SCENARIO 1: children receptors (representing the weakest target always selectable in Risk assessment tools) in a residential use of the site; active exposure routes are soil ingestion, dermal contact soil inhalation, because in the park children play with soil staying outside.

. SCENARIO 2: adult-worker receptors (representing the most exposed target because of the high number of hours spending at work) in an industrial use of the site, considering only vapor inhalation as active exposure routes, as people work inside.

A previous analysis (Pinedo et al., 2012) of soil samples from "Jardines de Pereda" proved the need to perform a site specific risk assessment, as the detected TPH concentration was above the threshold of 50 mg/kg (Nivel Generico de Referencia for TPH, Royal Decree 9/2005).
Furthermore, the presence of only three TPH fractions was detected.
In order to study the environmental behavior of all TPH fractions, a soil spiking was therefore planned. In fact, the soil of interest showed such a level of TPH concentration that it cannot considered clean: the analysis of spiked soil samples is justified by the will to know how a hypothetical oil spill which is more pollutant and complete in all carbon ranges could affect the quality and the risk of the soil of interest.