Groundwater salinization in arid coastal wetlands: a study case from Playa Fracasso, Patagonia, Argentina

Abstract

The origin of the high salinity in the groundwater of a coastal wetland in an arid climate was studied in the Playa Fracasso marsh, located on the northwest coast of the extra-Andean Patagonia. Research was carried out by means of the design of a network of soil pits and short piezometers in the marsh and the surrounding landforms. Continuous fluctuations of the water table, in situ physical and chemical properties, major ions (Ca 2? , Mg 2? , Na ? , K ? , Cl -, SO 4 2-, HCO 3 -) and stable isotopes ( 18 O and 2 H) in groundwater, as well as soil salinity, were measured. The combined analysis of the hydrodynamics, the ion ratios rCa 2? /rCl -and rMg 2? /rCa 2? vs. rCl -and the isotopic composition made it possible to recognize an area within the high marsh in which the origin of groundwater is mainly marine and another in which the contributions are of mixed origin. By means of the analysis of rCl -vs. d 18 O, a salinization process with no change in isotopic composition was identified. Its interpretation, together with those of the soil salinity profiles and the records of the fluctuations in electrical conductivity associated with extraordinary tides, was used to define a conceptual model of salinization which could be useful to understand other coastal wetlands under similar arid climatic conditions. It consists in a cyclical mechanism of evapotranspiration, precipitation, dissolution and transport of salts during tides.

Vegetation response to rainfall seasonality and interannual variability in tropical dry forests

“…It is important to understand the impact of changes in rainfall regimes on ecosystem function to quantify their changes on hydrological processes. For example, forest mortality through increased drought intensity followed by subsequent wetter years may result in either strong recharge events or abnormal runoff and flash flooding (Adams et al, 2012), with simultaneous increase in the risk of soil salinization because of groundwater rise (Alvarez et al, 2015;Assouline et al, 2015;Nagy et al, 2015). Changes in the seasonal rainfall distribution can also compromise water storage in dams and cisterns that store and supply water for drinking and irrigation during the dry season, with obvious implication for water resources management.…”

Precipitation/dissolution of marine evaporites as determinants in groundwater chemistry in a salt marsh (Península Valdés, Argentina)

“…4). Even though a high salinity level is to be expected in that site due to the fact that tidal flooding is infrequent, a water mixing process with the least saline contribution from the bajadas occurs (Alvarez et al, 2015a).…”

“…The main geomorphological features of Fracasso Beach are a sandy tidal plain, the marsh and coalescing alluvial fans, known as bajadas (Fig. 1) (Alvarez et al, 2015a). The marsh is a low area with heights that do not exceed 8.5 m a.s.l.…”

Hydrogeochemical and Isotopic Tools (δ18O and δ2H) Applied to Understanding the Processes of Groundwater Salinization in Proterozoic Carbonate Aquifers: Evidence from the Semi-Arid Region of Northeastern Brazilian

“…Dentre os diferentes tipos de abordagens, a integração dos métodos hidroquímicos e isotópicos consistem em um importante mecanismo na identificação das possíveis fontes de salinização e renovação das águas subterrâneas. (Shiavo et al, 2013;Carreira et al, 2014;Han et al, 2014;Alvarez et al, 2015).…”