Search results for "hydrochemistry"
showing 4 items of 4 documents
Carbonate precipitation in the alkaline lake Specchio di Venere (Pantelleria Island, Italy) and the possible role of microbial mats
2016
Abstract Alkaline lakes like the hydrothermally affected lake Specchio di Venere (Pantelleria Island, Central Mediterranean) are typical geological settings harbouring calcified microbial mats. The present work is focused on the discrimination between biotic and abiotic processes driving carbonate precipitation in this lake, using hydrochemical, mineralogical and isotopic data. Hydrochemical analyses demonstrate that the lake is nearly 10−fold supersaturated with regard to aragonite and seasonally reaches hydromagnesite supersaturation. Microscopic observations depict organosedimentary laminated structures consisting of microbial communities and aragonitic precipitates, which are rather dis…
Dissolved silica in the Garonne River waters : changes in the weathering dynamics
2000
The major ion chemistry of the Garonne River is indicative of seasonal variations in the weathering dynamics of the drainage basin. Using the geochemical model MEGA for calculation of the contribution of atmospheric CO2 to the total bicarbonate fluxes exported by the Garonne River allows estimations of the concentrations of the major dissolved elements that originate from silicate- and carbonate-rock weathering. The molecular ratio SiO2/Al2O3 was calculated for the 1989–1992 period to identify the main type of weathering in the Garonne River, and montmorillonite was shown to be the major mineral occurring in the weathering products. The seasonal variations of the SiO2/Al2O3 ratio also showe…
Exposition des eaux souterraines peu profondes à Escherichia coli résistant aux antibiotiques : approche hydrochimique pour identifier les sources et…
2016
L'antibiorésistance est une préoccupation croissante en termes de santé humaine et animale au niveau international. Le but du travail est de suivre l'impact sur la qualité de l'eau dans le bassin versant de l’Ouche et évaluer la capacité des E. coli productrices de BLSE de type CTX-M à se propager et survivre dans les eaux. Une stratégie pour l’échantillonnage des eaux de surface et souterraines a été déployée selon les contextes hydrogéologiques, l'utilisation des terres et les STEP. L’approche hydrochimique s’appuie sur l’analyse des paramètres tels que les nitrates et le bore complétés par l’analyse de Terres rares dont le gadolinium et le suivi de produits pharmaceutiques (caféine, carb…
Factors controlling hydrochemical and trophic state variables in 86 shallow lakes in Europe
2003
In order to disentangle the causes of variations in water chemistry among European shallow lakes, we performed standardised sampling programs in 86 lakes along a latitudinal gradient from southern Spain to northern Sweden. Lakes with an area of 0.1 to 27 000 ha and mean depth of 0.4–5.6 m located in low to high altitudes were investigated within the EC project ECOFRAME 1–4 times during June–October 2000–2001. Several variables like conductivity, alkalinity, abundance of submerged plants, concentrations of suspended solids, total nitrogen and phosphorus were latitude-dependent decreasing from south to north. Secchi depth, concentrations of total nitrogen, total phosphorus, suspended solids, …