Sea spray influences water chemical composition of Mediterranean semi-natural springs

Sea spray aerosol (SSA) is responsible for the large-scale transfer of particles from the sea to the land, leading to significant deposition of a range of ions, predominantly Na+, K+, Mg2+, Ca2+, and Cl−. Up to now, there has been little research into the effects of SSA on spring water chemistry. Therefore, we sampled 303 semi-natural springs across Catalonia (NE Iberian Peninsula) and analysed the concentrations of 20 different ions and elements, and determined the impact of SSA (using distance to the coast as a proxy) as well as climate, lithology and human disturbances. We found that distance to the coast had a clear effect on the water chemical composition of springs, while accounting for potentially confounding factors such as anthropogenic water pollution (nitrate, NO3−), differences in lithology and annual rainfall. Our results showed that springs located closer to the coast had higher Cl−, SO42−, Na+, Mg2+, K+ and Ca2+ concentrations than those of springs located further away. Precipitation was generally negatively correlated with the concentration of almost all elements analysed. The concentration of NO3− increased with distance to the coast, concurrently with farming activities, located mainly inland in the study area. These results demonstrate that SSA has an important effect on the groundwater of coastal zones, up to a distance of around 70 km from the coastline. This analysis reveals the main natural and human processes that influence spring water chemistry in this Mediterranean region, information that could be helpful in similar regions for ecological studies, water quality policies, and for the improvement of predictions in the current context of global change.