Search results for "COLUMN"
showing 10 items of 1301 documents
CH4 oxidation in a boreal lake during the development of hypolimnetic hypoxia
2020
AbstractFreshwater ecosystems represent a significant natural source of methane (CH4). CH4 produced through anaerobic decomposition of organic matter (OM) in lake sediment and water column can be either oxidized to carbon dioxide (CO2) by methanotrophic microbes or emitted to the atmosphere. While the role of CH4 oxidation as a CH4 sink is widely accepted, neither the magnitude nor the drivers behind CH4 oxidation are well constrained. In this study, we aimed to gain more specific insight into CH4 oxidation in the water column of a seasonally stratified, typical boreal lake, particularly under hypoxic conditions. We used 13CH4 incubations to determine the active CH4 oxidation sites and the …
¿La ONU, irrecuperable? / 2
2005
Surface–bottom relationships in the Gulf of Salerno (Tyrrhenian Sea) over the last 34 kyr: Compositional data analysis of palaeontological proxies an…
2009
The palaeontological, geochemical and mineralogical records of core GNS84-C106 were analysed in order to reconstruct palaeohydrological changes and palaeoproductivity patterns in the Gulf of Salerno for the last 34 kyr. This approach, including compositional analysis of planktonic and benthic assemblages, gave an insight into the relationships between continental, sea surface and bottom environmental changes. The main source of variability of planktonic and benthic assemblages is related respectively to sea surface temperature and palaeobathymetry. Interrelated changes in surface salinity, nutrients, density gradient in the water column and organic fluxes at the bottom act as a secondary fa…
Separation of monoacylglycerols by reversed-phase high-performance liquid chromatography
1992
Abstract Reversed-phase high-performance liquid chromatography on a thermostated octadecylsilyl column was used to separate complex mixtures of monoacyglycerols formed by chemical deacylation of natural triacyclycerols. Acetonitrile-water mixtures were used for elution of the underivatized monoacylglycerols and a different refractometer was used for their detection. The order of elution of monoacylglycerols in complex mixtures varies as a function of the chain length, unsaturation, positional isomerism, analysis temperature and eluent water concentration. The peak areas were representative of the amounts of monoacylglycerols detected. The method can be applied to compositional analysis and …