Assessing the impact of both a forest and a waste fire on the soil chemistry of two areas in Campania region

In the last decades, intentional illegal burnings increased in the numbers and became a problem of a global interest. As a consequence, human beings can be exposed to potentially toxic elements (PTEs) released during the combustion, dispersed by the wind, and accumulated in the fire’s ashes (Dimitrios, 2020).

Several studies highlighted that PTEs content in the deposited ashes can modify the chemical and the physical characteristics of the soil and, therefore, it can influence the development and growth of local microorganisms and vegetation (Raison, 1979). The geochemical characteristics of ashes depend on the nature of burned material (Dermibas et al. 2003) and on many other variables such as the intensity of combustion, the composition of the underlying soil, the bedrock type, etc.

The aim of the study was to verify at two different sites the environmental impact related with the on-set of two fire events occurred in Campania region (Southern Italy) during the 2017 summer season. One of the fires involved a forest (on the slopes of Mt. Somma-Vesuvius) and one affected a waste disposal site, known as Ilside (close to the city of Caserta). The variation occurred to concentration of PTEs in topsoil was used for the purpose.

Specifically, at both locations, 30 topsoil samples were collected before and right after the fire events. In total 60 samples were collected at the surroundings of Mt. Somma-Vesuvius slopes and 60 at the surroundings of Ilside. The post-fire samples were collected in correspondence of pre-existing sampling sites along the main wind directions recorded at the time of the fires.

To explore the potential elemental contamination occurred in soils due to the fire events, the Enrichment Factor (EFs) of a selection of PTEs was determined and mapped for individual samples. A predominant enrichment of Hg was identified for both areas.

Further, a combined application of multivariate statistics and geospatial analysis was also performed on the calculated EFs.

For the Ilside site (where special waste and e-waste were involved in burning) the association of Hg, Tl, Cu and Co was identified as the main responsible of data variability; for the Vesuvian area, the association of Hg, Cu and Cr was found to be quite strong and possibly associated with forest biomass burning.

This study highlighted how different can be the chemical evidence left by fires occurring in the environment depending on the nature of the burnt materials. At same time, result showed that even the burning of biomasses proceeding from a natural area can input in the environment PTEs which can potentially generate an increase of the pre-existing degree of environmental hazard.

References

Dermibas, A., 2003. Toxic Air Emissions from Biomass Combustion, Energy Sources, 25:5, 419-427.

Dimitrios E. A., 2020. Suburban areas in flames: Dispersion of potentially toxic elements from burned vegetation and buildings. Estimation of the associated ecological and human health risk. Environmental Research, Volume 183, ISSN 0013-9351.

Raison, R.J., 1979. Modification of the soil environment by vegetation fires, with particular reference to nitrogen transformations: a review. Plant Soil 51, 73–108.