Holocene paleoenvironmental evolution of a playa-lake system in southwestern Iberia (western Mediterranean region)

The Mediterranean region is a vulnerable area affected, among other environmental threats, by aridification and desertification processes that can cause soil salinization in areas rich in evaporite deposits. This is especially evident in the evaporite lake systems of southern Iberia, where a combination of both natural and anthropogenic causes gives rise to aridification and land degradation. In this study, we performed a multiproxy analysis (magnetic susceptibility, lithology, bulk organic geochemistry, inorganic geochemistry, and mineralogy) in the sedimentary record of the Laguna de la Ballestera playa-lake in southwestern Iberia in order to reconstruct the environmental evolution of this evaporitic area and potential human impacts during the Holocene. The most humid period registered in the Laguna de la Ballestera record was the Early Holocene with significant catchment runoff and high lake water levels. The lake size, lake level and catchment runoff decreased throughout the Middle and Late Holocene. This aridification trend is especially evident in the Late Holocene when gypsum precipitation enhanced. The highest gypsum contents were registered in the last millennium, especially after 1600 cal yr CE, probably related to important changes in the hydrology of the area, shifting from a (semi) permanent to a temporal and seasonal hydrological regime. These trends represent the local environmental responses to the western Mediterranean climate during the Holocene. The studied proxies did not evidence any potential human impact until the last century, when the catchment runoff and the playa-lake hydroperiod changed, probably related to changes in the land use.