Significance of atmospheric inputs of calcium over the southwestern Mediterranean region: High mountain lakes as tools for detection

Abstract

We quantified dry and wet atmospheric deposition of calcium over the southwest Mediterranean region and we assessed its impact on calcium dynamics of two high mountain lakes differing in morphometry and catchment characteristics. Atmospheric deposition of Ca averaged 40 mmol m −2 yr −1 , and it showed a seasonal pattern similar to that reported for Saharan dust export to the Mediterranean region, with maxima during spring and summer. Ca enrichment from nonmarine sources was significantly related to the TOMS (Total Ozone Mapping Spectrometer) aerosol index. Atmospheric inputs significantly affected Ca concentration of the selected lakes, which do not presumably receive significant Ca inputs from weathering. The intensity of the effect depended on their corresponding sensitivities to evaporation. Total atmospheric inputs of Ca to each study lake catchment (11300 and 3100 moles) were enough to explain the lake Ca content (5400 and 111 moles, respectively). The results obtained in this study reveal that atmospheric inputs, particularly Saharan dust deposition, may be a significant source of calcium to remote mountain lakes.