Biological and physical modification of carbonate system parameters along the salinity gradient in shallow hypersaline solar salterns in Trapani, Italy
Abstract We investigated changes in the chemical characteristics of evaporating seawater under the influence of microbial activity by conducting geochemical analyses of the brines and evaporite sediments collected from solar salterns in Trapani, Italy. The microbial activity had a substantial effect on the carbonate system parameters. Dissolved inorganic carbon (DIC) was substantially removed from the brine during the course of evaporation from the seawater to the point where calcium carbonate precipitates, with an accompanying decrease in its carbon isotopic composition (δ 13 C DIC ) to as low as −10.6‰. Although the removal of DIC was due to calcium carbonate precipitation, photosynthesis…
Efficient recycling of nutrients in modern and past hypersaline environments
The biogeochemistry of hypersaline environments is strongly influenced by changes in biological processes and physicochemical parameters. Although massive evaporation events have occurred repeatedly throughout Earth history, their biogeochemical cycles and global impact remain poorly understood. Here, we provide the first nitrogen isotopic data for nutrients and chloropigments from modern shallow hypersaline environments (solar salterns, Trapani, Italy) and apply the obtained insights to ¿ 15 N signatures of the Messinian salinity crisis (MSC) in the late Miocene. Concentrations and ¿ 15 N of chlorophyll a, bacteriochlorophyll a, nitrate, and ammonium in benthic microbial mats indicate that…