Search results for "ISOTOPIC FRACTIONATION"
showing 5 items of 5 documents
Isotopic fractionation due to N2 fixation in various grain legumes
2004
National audience
Isotopic composition of single rain events in the central Mediterranean
2008
[1] The ratios of stable isotopes of single rain events were investigated during the period October 2005 to September 2006 in the central Mediterranean. Clear seasonal trends were identified in both oxygen isotope ratios and the deuterium-excess parameter, and these were ascribed to the dominant circulation systems during both cold and hot intraannual periods. Rain events were classified on the basis of the origin of rain-bearing systems. Air masses coming from the south usually give rise to rainwater with a low deuterium excess. Air masses coming from the north and the northeast are often dry and cold, and are associated with high evaporation from the Mediterranean Sea that occurs under is…
Modelling hydrolysis: Simultaneous versus sequential biodegradation of the hydrolysable fractions
2018
Hydrolysis is considered the limiting step during solid waste anaerobic digestion (including co-digestion of sludge and biosolids). Mechanisms of hydrolysis are mechanistically not well understood with detrimental impact on model predictive capability. The common approach to multiple substrates is to consider simultaneous degradation of the substrates. This may not have the capacity to separate the different kinetics. Sequential degradation of substrates is theoretically supported by microbial capacity and the composite nature of substrates (bioaccessibility concept). However, this has not been experimentally assessed. Sequential chemical fractionation has been successfully used to define i…
Biogeochemical evaluation of historical sediment contamination in the Gulf of Palermo (NW Sicily): Analysis of pseudotrace elements and stable isotop…
2012
Abstract Sedimentary biogeochemical data from the Gulf of Palermo, which borders one of the major urban and industrial areas of the central Mediterranean, provide a decennial–centennial-scale record of the effects of human activity on this coastal environment. In this study we report trace elements (TE), C org /N tot ratios, δ 13 C org , and δ 15 N tot from dated ( 210 Pb) sediments collected in two coastal stations variably influenced by urban/fluvial loadings and illegal dumping and we compare them with published data for offshore sediments, in order to investigate at a large spatial scale the influence of on-land activities on sedimentary marine system. TE were generally low except for H…
Holothuria tubulosa Gmelin 1791 (Holothuroidea, Echinodermata) enhances organic matter recycling in Posidonia oceanica meadows
2014
Abstract The role of Holothuria tubulosa in organic matter recycling of Posidonia oceanica detritus was estimated in a laboratory feeding experiment. The individual mean ingestion rate of seagrass detritus by holothurians was evaluated and carbon and nitrogen stable isotopes, carbon and nitrogen content and C:N ratio analyzed in H. tubulosa , P. oceanica detritus and surface sediment. Results showed that H. tubulosa is capable of ingesting from 30% to 100% of the detritus produced by P. oceanica meadows, depending on the holothurian density. Stable isotope analysis provided evidence for the assimilation of seagrass detritus by H. tubulosa as their signatures were compatible with 1 trophic l…