Effect of sea spray on the chemistry of granitoid aquifers in coastal areas

摘要

A hydrogeochemical investigation performed in an area of Southern Sardinia characterized by the outcrop of granitoid rocks facing the Mediterranean Sea has revealed that the dissolution of marine salts transported by the wind is an important input in the hydrologic system, capable of influencing the whole process of water-rock interaction. This can be summarized in the following way: dissolution of carbonate and sulfate minerals is the prevalent source of dissolved solids for inland waters; moving toward the sea, the input of marine salts by sea-spray increases progressively and produces disequilibrium in the distribution of some species between water and the sorbents/exchangers in the soils/aquifer substrate. Na and K compete with alkaline earth elements for adsorption sites, with a remarkable increase of the dissolved Ca + Mg content and an equivalent loss of Na + K. The result is a salinization process similar to those previously observed in aquifers intruded by sea water.