Karakterizacija kerogena tipa III Tirolskog škriljca (Hahntennjoch, Austrija) zasnovana na njegovim oksidacionim proizvodima

A 29-step alkaline permanganate degradation of type III kerogen from Tyrolean (Hahntennjoch, Austria) oil shale was performed. A high yield of oxidation products was obtained (93.7 % relative to the original kerogen): 0.5 % neutrals and bases, 19.5 % ether-soluble acids and 58.9 % of precipitated (PA). A substantial amount of kerogen carbon (14.8 %) was oxidized into carbon dioxide. The organic residue remaining after the final oxidation step was 6.9 %. The PA components were further oxidized and the total yields relative to original PA were 1.0 % neutrals and bases and 59.0 % ether-soluble acids, the non-degraded residue being 29.3 %. Detailed quantitative and qualitative analysis of all oxidation products suggested the Tyrolean shale kerogen to be a heterogeneous macromolecular substance consisting of three types of structures differing in composition and susceptibility towards alkaline permanganate: the first, resistant, presumably composed of aromatic structures linked by resorcinol ethereal bonds; the second, combined in nature, the aliphatic part comprising methyl-substituents and short cross-links, both easily oxidized into CO2, water and low molecular weight acids and aromatic structures yielding aromatic diand tri-carboxylic acids as oxidation products; finally the third, composed of aliphatic cross-links and substituents, alicyclic (and/or heterocyclic) and some aromatic structures, bound into units moderately resistant towards oxidation. The overall yields of kerogen and PA oxidation products lead towards a balance between aromatic, alkane monoand dicarboxylic and alkanepolycarboxylic acids, suggesting a shift of the structure of Tyrolean shale kerogen from typical aromatic reference type III towards a heterogeneous aromatic-aliphaticalicyclic type structure.Stupnjevitom degradacijom kerogena tirolskog škriljca pomoću alkalnog permanganata dobijeni su visoki prinosi oksidacionih proizvoda. Dobijene nerastvorne kiseline naknadno su degradovane u 8 stupnjeva. Detaljna GC-MS analiza kiselina rastvornih u etru, dobijenih degradacijom kerogena, potom intermedijarnih nerastvornih kiselina, pokazala je da je kerogen tirolskog škriljca heterogena makromolekularna supstanca i da se sastoji iz tri tipa strukture, različitog sastava i različite osetljivosti na primenjeno oksidaciono sredstvo. Prvi tip je aromatične prirode sa rezorcinolnim etarskim umreženjem, otporan prema alkalnom permanganatu. Drugi se vrlo lako oksiduje, a sastoji se od aromatičnih struktura umreženih kratkim alifatičnim nizovima i sa većim udelom metil-supstituenata. Ovaj tip strukture je pri oksidaciji dao visok prinos SO2, alifatične kiseline malih molekulskih masa i aromatične dii trikarboksilne kiseline u visokom prinosu. Treći tip strukture je srednje osetljivosti na permanganat, a sastoji se od alicikličnih i/ili heterocikličnih i aromatičnih jezgara povezanih alifatičnim nizovima srednjih dužina. Kvantitativan odnos alifatičnih, aromatičnih i alkan-polikarboksilnih kiselina u oksidacionim proizvodima pokazao je da struktura kerogena tirolskog škriljca odstupa od tipskih, dominantno aromatičnih struktura tipa III, kojima pripada po svom H/C-O/C atomskom odnosu, i da je pomerena ka heterogenim, aromatično-alifatično-alicikličnim strukturama tipa II

Preserved precursors in Pumpherston shale kerogen revealed by oxidative degradation

An optimised stepwise alkaline permanganate degradation was shown to have potentials in elucidating the genesis pathway and the origin of kerogens, and, more specifically, to reveal preserved precursors in a kerogen matrix. Thus, Pumpherston shale kerogen, used as the substrate in this study, was found to be of mixed origin, i.e., to contain both inherited resistant algal structures (B. braunii A and B algaenans), as well as resistant biomacromolecular components of continental flora (cutans). It is suggested that this kerogen or parts of it were formed by the selective preservation pathway

Effects of addition of clay minerals on the fatty acid fraction of a podzol soil

International audienceThe Al horizon of a sandy podzol soil, with a very small proportion of clay-sized material, was sampled and homogenized. Samples, both with and without supplementation with 150 g clay minerals kg-1, natural heteroionic bentonite (saturated with Na, Ca, Mg, K), Mg-bentonite or Fe-kaolinite, were moistened to two-thirds of water-holding capacity and incubated at 28°C for 16 weeks. After incubation, lipids were extracted with 3:1 light petroleum: ethylacetate mixture in a Soxhlet apparatus as unbound components (directly extractable by organic solvents) and bound components (only extractable after treatment with acids). Monoacids (free and esterified), diacids, ketoacids and hydroxyacids were isolated from the two lipidic fractions (unbound and bound) by column chromatography. The different components of each family were analyzed by gas chromatography (GC) or gas chromatography-mass spectrometry (GC-MS). Incubation without supplementation generated a selective decrease in abundance of free mono-acids in unbound and bound fractions. The decrease was in inverse proportion to the chain-length of components. Soil supplementation with bentonite (homoionic or heteroionic) did not induce an overall quantitative change, but promoted a transfer of fatty acids from the unbound to the bound fraction, increased the exchange between free and esterified monoacids (transesterification) and stimulated hydrolysis of glycerides. In contrast, soil supplementation with Fe-kaolinite caused much decomposition or biotransformation of monoacids but it did not induce change either in the intensity of transesterification in the wax ester fraction or in the intensity of hydrolysis in the glyceride fraction. Copyright \textcopyright 1995, Wiley Blackwell. All rights reserve

The internal double-bond insertion: A side reaction of aliphatic hydrocarbons degradation in soil

International audienceAfter supplementing the topsoil of a glossic luvisol with pure alkanes and incubating, soil lipids were extracted. Alkanes and alkanoic monoacid fractions were separated and analysed by gas chromatography and mass spectrometry. Alkylation was used for determining the double-bond position in the carbon chain. During the incubation of alkanes in soil, fatty alcohols, fatty acids and methylketones are generally generated. In our study, alkenes (chiefly alk-9-enes) were also generated from the internal dehydrogenation of alkanes freshly added to the soil. Natural soil alkanes were not involved in this process. The generated alkenes did not persist in the soil. They were terminally oxidized on either of the two terminal methyl groups. Consequently, two different alkenoic monoacids can be generated from each alkene. \textcopyright 1994

Incorporation of natural monoacids from plant residues into an hydromorphic forest podzol

International audienceThe monoacid part of soil lipids was studied in a hydromorphic sandy podzol under pine trees (Pinus maritima sp.). The undecomposed forest-litter layer (L), the fragmented mycelium-invaded litter layer (F) and the A1 soil horizon were sampled, and analysed for total lipid and total monoacid contents. Total monoacids were separated into straight-chain components and terpenic components. Straight-chain monoacids were determined as free acids and esters of fatty alcohols and of glycerol. Among these components, branched alkanoic acids occurred in the A1 soil horizon. Alkenoic acids were mainly determined as glycerides. Free n-alkanoic acids were mainly produced in soil from terminal oxidation of plant n-alkanes and plant n-alkanols. Free alkanoic acids with the longest carbon chains and alkanoic acids esterified as glycerides were concentrated in the A1 soil horizon. Terpenic monoacids were mainly diterpenic components from pine resin. Their concentration decreased markedly during the decomposition of plant debris. Copyright \textcopyright 1994, Wiley Blackwell. All rights reserve

Triglyceride degradation in soil

International audienceTo study the fate of fatty wastes left by food industries in the soil, tristearin was chosen as a model molecular marker and its biodegradation followed in different types of soil in a laboratory experiment. Samples of three soils (controls and treatments) were incubated for periods of 1-4 weeks, at 20°C. A significant disappearance of total free lipids was observed. A detailed study of different lipid classes showed an increased activity by soil microorganisms. This resulted in the oxidation and hydrolysis of the added component, producing free stearic acid and esters (methyl stearate, ethyl stearate and propyl stearate). After 4 weeks, the amounts of these compounds decreased. They are certainly intermediate components in the biodegradation processes of triglycerides. The use of this pathway for the elimination of fatty wastes in soil seems to be all the more important as it is known that fatty acids, mono/diglycerides and glycerol are removed more easily than triglycerides

Migration of micropollutants in a dredging amended soil in Northern France

International audienceA river dredging sludge containing heavy metals and organic compounds was spread on an unsaturated soil in Northern France, and the evolution of the micro-pollutants was studied for 28 months. Metal concentration were higher after 28 months, whereas there was no accumulation of organic compounds. The metal balance in the soil was good, which was not the case for organic carbon. The unbalance could be explained by an increased mineralization of both the initial and the xenobiotic organic matter, induced by the addition of easily-biodegradable organic carbon into the soil and by humification. Micro-pollutant concentrations in the top layer of soil remained very high which could induce a contamination of plants

Exctractable soil lipids and microbial activity as affected by Bt and non Bt maize grown in a silty loam soil

International audiencePyrolysis-gas (Py-GC) chromatography was used to characterize extractable lipids from Bt and non-Bt maize shoots and soils collected at time of harvesting. Py-GC-MS (mass spectrometry) showed that the concentrations of total alkenes identified in non-Bt shoots and soils were 47.9 and 21.3% higher than in Bt maize shoots and soils, respectively. N-alkanes identified were of similar orders of magnitude in Bt and non-Bt maize shoots, but were 28.6% higher in Bt than in non-Bt soils. Bt maize shoots contained 29.7% more n-fatty acids than non-Bt maize shoots, whereas the concentrations of n-fatty acids in Bt soils were twice as high as those in non-Bt soils. Concentrations of unsaturated fatty acids in Bt maize shoots were 22.1% higher than those in non-Bt maize shoots, while concentrations of unsaturated fatty acids were 22.5% higher in non-Bt than in Bt soils. The cumulative CO2-C evolved from soils under Bt and non-Bt crops was 30.5% lower under Bt as compared to non-Bt crops, whereas when maize shoots were added to Bt and non-Bt soils, the decrease in CO2-C evolved were 16.5 and 23.6%, respectively. Our data showed that the cultivation of Bt maize significantly increased the saturated to unsaturated lipid ratios in soils which appeared to negatively affect microbial activity

Hydroliquefaction of green wastes to produce fuels

International audienceThe direct liquefaction of a biomass composed of a mixture of wastes (straw, wood and grass) was studied using Nickel Raney as catalyst and tetralin as a solvent. Tetralin allows to solubilize green waste from 330 °C at relatively low hydrogen pressure, and avoids the recondensation of the intermediate products. The green waste deoxygenation results mainly from a decarboxylation reaction. The addition of Raney Ni in the feed, increases the gas yield due to methane formation, without diminishing the yield in solvolysis oil. The catalyst hydrogenolyses the small molecules present in the light fraction. Moreover, it improves the quality of the oil by increasing the hydrogen transfer between the solvent and the solvolysis oil. As a consequence, the oxygen content decreases and the yield of oil soluble in hexane strongly increases. The catalyst allows to obtain straight long chain alkanes (C13-C26), which result from the hydrogenation of the extractives compounds of the green waste