Trace elements in the water column of high-altitude Pyrenean lakes: Impact of local weathering and long-range atmospheric input.

High altitude (alpine) lakes are efficient sentinels of environmental processes, including local pollution and long-range atmospheric transfer, because these lakes are highly vulnerable to ongoing climate changes and increasing anthropogenic pressure. Towards improving the knowledge of trace element geochemistry in the water column of alpine lakes, we assessed 64 physico-chemical parameters, including macro- and micronutrients, major and trace element concentrations in the water column of 18 lakes in the Pyrenees, located along the border between France and Spain. Lake depth, morphology, retention time and watershed rock lithology did not exhibit sizable impact on major and trace element concentrations in the water column.

Kinetics and mechanisms of cyanobacterially induced precipitation of magnesium silicate.

The biomineralization of CO , in the form of carbonate minerals, is considered as one of the efficient solutions of atmospheric CO removal, allowing stable and sustainable storage of this greenhouse gas. Cyanobacteria are among the most powerful microorganisms capable of precipitating carbonate minerals, both in the present and in the past. In the modern environments, high Si concentration during geoengineering biomineralization could occur due to dissolution of Mg-bearing primary silicates such as olivine.

The Response of Extracellular Polymeric Substances Production by Phototrophic Biofilms to a Sequential Disturbance Strongly Depends on Environmental Conditions.

Phototrophic biofilms are exposed to multiple stressors that can affect them both directly and indirectly. By modifying either the composition of the community or the physiology of the microorganisms, press stressors may indirectly impact the ability of the biofilms to cope with disturbances. Extracellular polymeric substances (EPS) produced by the biofilm are known to play an important role in its resilience to various stresses.

Diel cycles of carbon, nutrient and metal in humic lakes of permafrost peatlands.

Despite the importance of surface waters of permafrost landscapes in carbon (C) emission and dissolved C and metal storage and export, the majority of available observations in high latitude aquatic systems deal with punctual or seasonal sampling without accounting for diurnal variations in temperature and primary productivity-respiration cycles. Towards providing comprehensive understanding of diel variations in CO emission, organic C and element concentrations in lakes of frozen peatlands, we monitored, each 2 h over 2 days, the water temperature, pH, CO fluxes, CO, CH, dissolved organic and inorganic carbon (DOC and DIC, respectively), nutrients, carboxylic acids, bacterial number, and major and trace elements in two acidic (pH = 3.6 and 4.

Elemental and Isotopic Variations of Copper and Zinc Associated with the Diel Activity of Phototrophic Biofilm.

The response in metal concentrations and isotopic composition to variations in photosynthetic activity of aquatic micro-organisms is crucially important for understanding the environmental controls on metal fluxes and isotope excursions. Here we studied the impacts of two successive diel cycles on physicochemical parameters, Cu and Zn concentrations, and isotopic composition in solution in the presence of mature phototrophic biofilm in a rotating annular bioreactor. The diel cycles induced fluctuations in temperature, pH, and dissolved oxygen concentration following the variation in the photosynthesis activity of the biofilm.