Sea salt aerosol groundwater salinization in the Litorale Romano Natural Reserve (Rome, Central Italy)

Abstract

A yearly survey in a piezometric network was realized in the Litorale Romano Natural Reserve (Rome, Central Italy), collecting water table and chemo-physical data. Monthly chemo-physical surveys highlighted a groundwater salinization variability in a coastal unconfined aquifer. The aquifer is mostly composed by aeolian sands of a still preserved dune ridge environment, on which a pine forest develops. The groundwater salinity variability resulted is connected to the wind pattern and rainfalls. In fact, wind speed higher than 4 m/s is responsible for generating sea salt aerosols (SSA) from sea surface. A statistical analysis was performed for wind with a speed higher than 4 m/s, to detect wind orientation. The dry deposition of SSA on the tree foliage appeared correlated to the westerly winds, blowing in the springtime. When the rainy season occurs, the SSA is washed out from the trees and it is directed to groundwater, where an enhancement of the Electrical Conductivity (EC) values is noticed. Whenever rain events occur and winds are not westerly, a dilution of groundwater salinity takes place and consequently a reduction of EC. Chemical analyzes were realized as well. They confirmed that groundwater of piezometers located close to the coast line is enriched of SSA elements.