Insoluble Organic Fraction Research Articles

Expansion and rapid retreat of the West Antarctic Ice Sheet in eastern Ross Sea: possible consequence of over-extended ice streams?

Marine geological data from the eastern Ross Sea provide compelling evidence that the West Antarctic Ice Sheet extended to the continental shelf break during the last glacial maximum. Swath bathymetry records show mega-scale glacial lineations within each of the four large glacial troughs on the shelf. These features extend virtually uninterrupted across the shelf and have sharp lateral boundaries. Sediment cores that sampled the lineations recovered diamicton that is interpreted as deformation till. The combined data indicate streaming ice. The great extent of the paleo-ice streams (up to 1000 km in length) is attributed to the fact that they flowed across unconsolidated sedimentary strata. Geomorphic features that are known to form at the retreating grounding line, such as recessional moraines and ridges, are restricted to the southeastern portion of the shelf. Iceberg furrows that occur at depths of up to 650 m overprint mega-scale lineations. These deep furrows are interpreted as having been formed by icebergs calved from the grounding line of the ice sheet, which indicates the absence of a fringing ice shelf. Sediment cores sampled a thin layer of glaciomarine sediments resting sharply on till. Sub-ice shelf deposits, similar to those sampled in the western Ross Sea, were not recovered in the eastern Ross Sea. These combined results imply rapid retreat of the ice sheet from the shelf. Crosscutting lineations with different orientations indicate changes in flow direction that probably occurred as the ice profile was lowered and the physiography of the sea floor across which the ice sheet was retreating changed. Grounding zone wedges vary in number and location within individual troughs, which indicates diachronous retreat of ice streams. Due to a lack of carbonate material for radiocarbon dating, all radiocarbon ages were derived from acid insoluble organic (AIO) fractions. These dates indicate early retreat of the ice sheet relative to the western Ross Sea and other areas of west Antarctica. However, the older dates must be viewed as suspect, due to a paucity of diatomaceous material and contamination from old carbon. While we were not successful at constraining the timing of ice sheet retreat from the continental shelf, the data do indicate that the ice sheet was grounded on the shelf during the LGM.

The contribution of water soluble and water insoluble organic fractions to oxygen uptake rate during high rate composting

This study aims to establish the contribution of the water soluble and water insoluble organic fractions to total oxygen uptake rate during high rate composting process of a mixture of organic fraction of municipal solid waste and lignocellulosic material. This mixture was composted using a 20 l self-heating pilot scale composter for 250 h. The composter was fully equipped to record both the biomass-temperature and oxygen uptake rate. Representative compost samples were taken at 0, 70, 100, 110, 160, and 250 h from starting time. Compost samples were fractionated in water soluble and water insoluble fractions. The water soluble fraction was then fractionated in hydrophilic, hydrophobic, and neutral hydrophobic fractions. Each fraction was then studied using quantitative (total organic carbon) and qualitative analysis (diffuse reflectance infrared spectroscopy and biodegradability test). Oxygen uptake rates were high during the initial stages of the process due to rapid degradation of the soluble degradable organic fraction (hydrophilic plus hydrophobic fractions). Once this fraction was depleted, polymer hydrolysis accounted for most of the oxygen uptake rate. Finally, oxygen uptake rate could be modeled using a two term kinetic. The first term provides the oxygen uptake rate resulting from the microbial growth kinetic type on easily available, no-limiting substrate (soluble fraction), while the second term considers the oxygen uptake rate caused by the degradation of substrate produced by polymer hydrolysis.

ANALYSIS OF SOLUBLE ORGANIC FRACTION IN PARTICULATE MATTER FROM A DIESEL ENGINE BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY

Soluble organic fraction (SOF) and insoluble organic fraction (IOF) in particulate matter (PM) emission from diesel engine are separated by supersonic elution. The SOF in PM is analyzed by combined gas chromatography/mass spectrometry. Experiments are carried out in a six-cylinder, turbo-charged and intercooled, direct injection diesel engine. A typical 13-mode operating conditions test cycle is performed on the diesel engines. PM emissions from the diesel engine at the thirteen operating conditions are collected. The analysis results show the SOF emission is lower at lower loads, and rises with increasing loads. The dominant component in the SOF is the paraffin hydrocarbon, secondly, is the aromatic hydrocarbon. The majority of paraffin hydrocarbon is the linear paraffin hydrocarbon. The greater parts of aromatic hydrocarbon are the naphthalene and phenanthrene. The aromatic hydrocarbons emission rises with increasing loads. Research results of C atomicity in paraffin hydrocarbons show the linear paraffin hydrocarbons (from Tet-radecane to Heptadecane) are almost burned up at lower loads, and some components of the SOF are not directly from fuel, but from lubricant oil or middle polymerization products of fuel. More fuel supply leads to more paraffin hydrocarbons emission at higher loads, and some components of the SOF are from fuel decomposing at high temperature. Research results of C atomicity in aromatic hydrocarbons show most of aromatic hydrocarbons have higher C atomicity are burned up at higher loads, and more compounds of aromatic hydrocarbons are seen at lower loads.

Effect of pH and the role of organic matter in the adsorption of isoproturon on soils

Equilibrium measurements were carried out with the herbicide isoproturon on natural adsorbents (brown forest-, chernozem-, sandy soils and quartz) in different buffered media (pH 5, 7, 8 phosphate buffer). Adsorption isotherms were fitted by a multi-step adsorption equation providing numerical information used in the environmental propagation models and risk assessment works. In the adsorption of the slightly polar isoproturon the dissolved organic matter of the soil and the pH play an important role. At molecular level, results are interpreted by taking into consideration the hydrophobic interaction and the formation of hydrogen bonds between the surface and the solute. The observed adsorption behavior indicates that the organic matter content of the soils and its soluble fulvic acid, alkaline soluble humic acid and insoluble humin fractions were considerable different. The chernozem soil containing the highest amount of insoluble organic fraction proved to be a very efficient adsorbent. The brown forest and the sandy soils exhibit rather similar adsorbent properties but at pH 7 the latter containing more fulvic acid adsorbs less isoproturon due to the enhanced solubility of the soil organic matter. In alkaline conditions the negatively charged solute and the surface repel each other and the hydrophobic interactions are also weaker than in neutral media.

FREE AND NON-CRYSTALLINE FE-OXIDES TO TOTAL IRON CONCENTRATION RATIOS CORRELATED WITH 14C AGES OF THREE FOREST SOILS IN CENTRAL TAIWAN

Three forest soils (Paleudult (Pedon 1), Dystrochrept (Pedon 2), and Hapludult (Pedon 3)), located on elevations ranging from 625 to 2350 m in central Taiwan, were selected to investigate the correlation between different iron forms (i.e., free Fe-oxides (Fed), noncrystalline Fe-oxides (Feo), total Fe (Fet)) and 14C ages as well as their vertical distribution within diagnostic soil horizons. The 14C ages increased with increasing depth in each pedon. The percentage of the total (Fet) extracted by dithionite (Fed) increased with the 14C age of the alkaline insoluble organic (humin) fraction of the soil horizons, as did the difference between Fed and Feo (assuming crystalline Fe-oxides form). Total amounts of Fe (Fet), however, were not related to the 14C ages of different soil horizons. Statistical analysis indicates the R2 of Fed/Fet and (Fed-Feo)/Fet ratios to 14C ages are 0.938 and 0.926 (Pedon 1, n = 6), 0.892 and 0.756 (Pedon 2, n = 4), and 0.914 and 0.910 (Pedon 3, n = 5), respectively. The data presented in this study suggesting that the ratios of different forms of iron oxides are highly correlated with the age of soil horizons may be useful as relative age indicators in other areas.

Analysis of carbon and nitrogen forms in soil fractions after the addition of 15N-compost by 13C and 15N nuclear magnetic resonance.

A quantitative laboratory assessment of the different C and N forms in soil humus fractions was carried out by incubation of a mineral substrate after the addition of (15)N-labeled compost. The experimental design included (i) preparation of the (15)N-labeled organic matter (city refuse compost, 640 g kg(-1) wheat straw and K(15)NO(3) composted for 80 days), (ii) a further 80 day incubation of a mixture of the labeled compost with a mineral soil (32 g kg(-1)), (iii) measurement of stable isotope ratios, and (iv) isolation and structural comparison by (13)C and (15)N cross-polarization, magic-angle spinning nuclear magnetic resonance (NMR) of different organic fractions, i.e., soluble, colloidal (humic and fulvic type), and particulate (free organic matter and humin), from both the compost and the compost-treated soil. The results showed that the amide forms dominated in all of the newly formed N compounds, but an increased amount of alkali insoluble organic fractions was observed after incubation of the soil. The analysis of the insoluble, particulate fractions shows that nonextractable amides constitute the major pool of newly formed N compounds. The particulate soil fraction isolated by flotation in CHBr(3)-MeOH contained 16.8% of the total soil N and 26% of the (15)N. The (13)C NMR spectra showed that the fulvic acid-like fraction (7.6% of the soil N, 8.8% of (15)N) consisted almost completely of a C=O-containing carbohydrate material, whereas the humic acid-like fraction (20.3% of the total soil N, 8.6% of (15)N) resembled an oxidized lignoproteic fraction containing the most significant aromatic domain. The water soluble fraction was, in both soil and compost, the one with the highest isotopic abundance of (15)N (96%), but the (15)N NMR spectrum revealed minor amounts of soluble mineral N in this fraction and the remainder consisting of amide compounds.

舶用４ストロークディゼル機関の排気特性と性能に及ぼす乳化燃料油中の水粒子径の影響

Using emulsified fuel, with water particles dispersed in the continuous phase of fuel, is effective in suppressing the emission of polluting matter from spray combustors, such as diesel engines and boilers. This paper discusses the emission characteristics and the performance of a marine four-stroke diesel engine operated with emulsified fuels having different water particle diameters. The research especially focused on how the PM (Particulate Matter) and NOx (Nitrogen Oxide) emission was affected by the water particle diameter in emulsified fuel.In the engine experiment, we used Marine Diesel Fuel (MDF) in three emulsified fuels having mean water particle diameters of 3.94μm, 7.71μm, and 8.78μm. The following results were found:1. In comparison with using MDF, the emission level was decreased by about 10% to 40% by using emulsified fuels, and the smaller the mean water particle diameter of the emulsified fuel, the lower the NOxemission level.2. The PM, SOF (Soluble Organic Fraction), and ISF (Insoluble Organic Fraction) emission rates increased with use of emulsified fuel, especially in the low load area.3. The SFC (Specific Fuel Consumption) of emulsified fuel having the largest mean water particle diameter in this experiment was lower than that of the MDF. Among the three emulsified fuels, the smaller the mean water particle diameter, the higher the SFC.

Polyalkylphenyl-sulphonic acids with acid groups of variable strength from animal-vegetable wastes

The insoluble organic fraction isolated from rice-hulls residues and animal fecal matter mixture is sulphonated in liquid SO 3 at 200 °C to a water soluble sulphonate (III). III is compared to the sulphonate (IV) obtained from the same mix after composting. Both products have been found to contain mixtures of molecules with close molecular weight. These molecules consist of a central cicloaliphatic cluster with peripheral pending aromatic chains. III and IV appear to have the same sulphonation degree. However, the latter contains higher concentrations of cicloaliphatic fragments and of amide, phenol and ether bonds, but less carboxylic and amine functional groups. These differences may be reasonably traced back to the starting materials. By comparison with commercial lignosulphonates derived from the paper and pulp industry, the above arylsulphonates are likely candidates for a variety of applications in the chemical industry and in agriculture. We conclude that sulphonation, even under the drastic experimental conditions of this work, does not seem to erase the memory of the parent matter structure. This reaction is capable of upgrading recalcitrant organic matter in vegetable waste residues to an interesting variety of lignosulphonates.

PY-GC/AED and chemometric correlation to Characterize sewage sludges of different origins

The solid organic fractions of sewage sludges originating from food-processing and domestic (rural and urban) depuration systems of Lorraine (Northeast of France) were characterized by flash pyrolysis coupled with gas chromatography/atomic emission detector (Py-GC/AED). These analyses generated a high amount of data which could not be processed without a further step using a chemometric approach. Thus, a heuristic methodology was developed, relying on the application of pattern recognition methods, such as Principal Components Analysis, hierarchical classification and the k-means method generally used in chemometry. In order to avoid subjective selection and reduction of data, a signal treatment relying on the alignment and the segmentation of pyrograms was performed before to the statistical analysis. The gathering of test-samples analysed several times validated this methodology. The main chemometric results provided a typology of sludges which consisted in a classification in different groups, and allowed to display the characteristic peaks of each group. This chemometric analysis gathered a group of sludges with an average chemical composition characterizing stable organic material and pointed out the atypical chemical composition of several sewage sludges. These results demonstrated the efficiency of Py-GC/AED associated to chemometric methods for the global characterization of the insoluble organic fraction of sewage sludges. It could be possible to apply, with further calibration, to the monitoring of sludge composition during its treatment.

Characterization of the macromolecular organic content of sewage sludges by thermally assisted hydrolysis and methylation-gas chromatography–mass spectrometer (THM-GC/MS)

The aim of this study is to determine a methodology enabling us to simplify the information generated by thermally assisted hydrolysis and methylation (THM)-pyrograms of sludges and to provide an insight into the sludges according to their chemical composition. The insoluble organic fractions of 48 sewage sludges originating from industrial (food-processing and paper mill) and domestic (urban, small urban and rural) wastewater-treatment plants (WWTP) of the region of Lorraine (northeast of France) were characterized by THM-GC/MS. A relative quantification of the pyrograms by integration of the major peaks was then carried out. The results of this integration were plotted in a triangular diagram defined by the poles corresponding to the three major families evidenced in the pyrograms (lignin-derived, lipid-derived and nitrogenous compounds). This type of representation enables us to separate paper-mill sludges from the others, because they are characterized by high amounts of lignin-derived compounds. The majority of domestic sludges and food-processing sludges are gathered and characterized by an intermediate composition in lipid-derived, lignin-derived and nitrogenous compounds, but seven urban sludges show an evolution of their chemical composition towards the lipid pole. The domestic sludges can be separated from the others on the basis of their molecular nitrogenous distribution. Such a methodology is complementary with the qualitative analysis of pyrograms and makes it possible to approach the chemical composition of sludges, which governs their reactivity once they are disposed on soil.

Polyalkylphenyl-sulphonic acid with acid groups of variable strength from compost

The insoluble organic fraction (humin-like material, HLM) from rice hull–dairy cattle compost is well converted into water soluble HLM-sulphonate by reaction in liquid SO 3. Microanalytical, potentiometric, molecular weight, and NMR data are consistent with a highly homogeneous polymeric arylsulphonate having 4000 Da MW, 1.3 sulphonic groups per aromatic ring and significant content of carboxylic and phenolic groups. By comparison with structure–property relationships for commercial lignosulphonates derived from the pulp and paper industry, the above arylsulphonate is likely to be a candidate at a variety of applications in the chemical industry and in agriculture. Therefore, sulphonation is a means for upgrading composts HLM to the same uses as for commercial lignosulphonates.

Solid state CP/MAS 13C NMR of the insoluble organic matter of the Orgueil and Murchison meteorites: quantitative study

Solid state CP/MAS 13C nuclear magnetic resonance (NMR) study of the insoluble organic fraction isolated by HF/HCl treatment under an inert atmosphere from the Orgueil and Murchison carbonaceous meteorites is reported. Based on these spectra, eight different types of carbons (aro- and ali-linked CH3, CH2, aliphatic C-linked to heteroelements, protonated and non-protonated aromatic C, carboxyls and carbonyls) were identified, their relative amounts were determined and theoretical NMR-derived H/C atomic ratios were calculated. Comparison of these H/C ratios with those obtained from elemental analysis revealed that a large part of the carbons of the insoluble fraction of both meteorites are not detected by CP/MAS 13C NMR. Taking into account these undetected carbons, the relative abundance of aromatic carbons (as % of the total carbons) was calculated as between 69 and 78% in Orgueil and 61 and 67% in Murchison and thus shown to be much higher than previously thought. In addition, the NMR data allowed to calculate the ratio of non-protonated and protonated aromatic carbons. Based on previous studies on chemical and thermal degradation, the present NMR data were interpreted as reflecting the occurrence of highly substituted rather small aromatic moieties in these insoluble organic materials. Along with FTIR data, NMR results also pointed to a relatively high branching level in the aliphatic chains, especially for Murchison. According to the above results, the insoluble organic matter in these meteorites did not suffer a marked thermal maturation during the late hydrothermalism of the parent body. Its synthesis involved a statistical combination of all the possible bonds between -CH3, -CH2 and -CH radicals, producing both the aliphatic and the aromatic moieties. This model explains not only the chemical features of the chondritic insoluble organic material but also the typical FTIR signature of the interstellar medium. Therefore, organic material found in the interstellar medium and that incorporated in the most primitive objects of the solar system seem to share a common organosynthesis.

Organic constituents of cruds in Cu solvent extraction circuits.: I. Separation and identification of diluent-soluble compounds

Interfacial `cruds' from hydrometallurgical solvent extraction of copper ions were examined to assist in the establishment of potential causes of cruds. Diluent-insoluble, polar organics comprised the majority of the solid mass of crud; inorganic particulates and bacterial/fungi were not dominant. Procedures involving ultracentrifugation and acetone extraction were developed to separate these cruds into inorganic, soluble organic, and insoluble organic fractions, and were used to analyze 12 assorted extraction stage and strip stage cruds. UV–Visible and infrared spectroscopic comparisons of the materials with known standard alkarylhydroxyoxime (AAHO) reagents and hydrolysis products were made. Two cruds were further examined by thin layer chromatographic (TLC) separation. Cruds contained larger proportions of de-oximated AAHO than did the supernatant organic phase. Strip stage cruds contained more de-oximated AAHO, relative to the AAHO reagents, than did the respective extraction stage cruds. Cruds contained larger proportions of aliphatic carboxylic acids and aliphatic carboxylic esters, than did the respective supernatant organic solutions. Copper complexes of AAHO reagents were not concentrated in the crud. The polarity of the diluent-insoluble organics was reflected in TLC behavior. Diluent-insoluble organics contained large amounts of carboxylic acids and esters. In experimental trials of the reconstitution of crud from decanted organic and aqueous phases, added diluent-insoluble organics obtained from crud were required for the reconstitution of crud, whereas inorganic particulates were not required. Inorganic particulates were incorporated into the reconstituted crud, but did not reconstitute crud in the absence of diluent-insoluble organics. It was hypothesized that low-polarity, diluent-soluble compounds are less likely to cause crud episodes, or even to be accumulated in crud, than are the diluent-insoluble organics.

Mechanisms of the Annual Cycling of Organic-Matrix Collagen from Spicules of the Gorgonian Leptogorgia virgulata

The insoluble organic matrix fraction from the spicules of the gorgonian Leptogorgia virgulata cycles annually. That is, in the summer, this fraction is predominantly collagenous while in the winter, collagen is largely absent. The mechanisms by which cycling occurs have been examined. It appears that spicules become etched and breaches form, probably via acidification and subsequent decalcification. Acidificationat the periphery of winter spicules, and presumably subsequent decalcification, has been verified using acridine orange. The internal organic matrix now becomes exposed to the hydrolytic action of such enzymes as acid phosphatase, which is secreted by secondary sclerocytes and scleroblasts. The digestive enzyme acid phosphatase has been localized throughout the year. In the winter, when the collagen content of spicules is lowest, there was strong labeling for acid phosphatase at the periphery of the spicules, suggesting that the enzyme may be involved in the removal of at least some portion of the organic matrix at this season. The level of enzyme activity in the polyps, heaviest in the fall and variable during the rest of the year, probably reflects seasonal changes in the productivity of the coastal waters in which the gorgonians live. Labeling for acid phosphatase was also strong in the winter in the cortical region of the axis. The enzyme may be digesting collagen that was transported to the axis. Labeling for acid phosphatase in the secondary sclerocytes was at a moderate level throughout the year. Additional key words: Cnidaria, octocoral, calcification, acid phosphatase, decalcification,

Examination of organic compounds from insoluble organic matter isolated from some Antarctic carbonaceous chondrites by heating experiments

Insoluble organic matter isolated from five Antarctic CM2 chondrites was heated in a thermal analyzer from room temperature to 800°C under helium atmosphere. Organic compounds from the thermal decomposition of the Yamato-791198 sample were studied by a gas chromatograph-mass spectrometer (GC-MS). The number of compounds identified was over 120, belonging mainly to the two following groups: 1. (1) benzene and naphthalene, and their alkyl derivatives; and 2. (2) sulfur-containing heterocycles and their alkyl derivatives. Small amounts of aliphatic hydrocarbons and nitriles were also detected. Relative amounts of compounds released from the five chondrite samples were monitored by the MS with increasing temperature. Yamato-74662 and Yamato-791198 showed organic compounds mainly over the temperature range of 300–600°C, while the other three (Yamato-793321, Yamato-86720, and Belgica-7904) did not show any, except small amounts of benzene. These results indicate that the insoluble organics in Yamato-74662 and Yamato-791198 possess a thermally labile organic fraction; whereas those in Yamato-793321, Yamato-86720, and Belgica-7904 do not and are graphitic. The difference between the insoluble organic fractions may be related to aqueous alteration and thermal metamorphism on the parent bodies.

British Museum Natural Radiocarbon Measurements XXII

The following list consists of dates, obtained by liquid scintillation counting of benzene, for archaeologic samples mostly measured between June 1987 and October 1989.Charcoal and grain samples were pretreated with 1M HCl followed by washing in water and, where considered necessary, with dilute alkali for the removal of humic acids. Wood samples were treated either in the same way, or, where large enough, were reduced to cellulose by the action of chlorine dioxide produced in situ. All antler and bone samples were treated with cold dilute acid. The term ‘collagen’ is used throughout to mean the acid insoluble organic fraction produced by this treatment. Peat samples were treated with dilute acid and alkali to separate the humin and humic acid fractions, which were dated individually.

Partitioning of 14C-photosynthate in developing kiwifruit

Kiwifruit ( Actinidia deliciosa [A. Chev.] C.F. Liang et A.R. Ferguson var. deliciosa cultivar ‘Hayward’) leaves were allowed to photosynthesise 14CO 2 and the fate of the photosynthate in different tissue zones of the fruit was studied at various stages of fruit development. Photosynthate moved into the fruit at all stages of fruit development examined (February, April, May). Proportionally more photosynthate was allocated to the core in May than in February. In May, a greater proportion of radioactive photosynthate was found at the stem end of the fruit than in the blossom end of the fruit. There was a diurnal pattern of incorporation of label into the insoluble residue and organic acid fractions in all tissues in February. Both the proportion and amount of radioactivity incorporated into the insoluble residue and organic acid fractions decreased as the fruit matured. The results support the concept that the core is metabolically more active than the inner cortex at late stages of fruit development, and indicate that the different concentrations of quinic and citric acids found in each tissue are not due to different rates of metabolism of photosynthate within the tissues. Evidence is given that the greater concentration of soluble solids occurring at the blossom end rather than the stem end of the fruit in April and May is not caused by incoming photosynthate.

Radiocarbon dating the Devensian Lateglacial in Britain: New evidence from Llanilid, South Wales

AbstractRadiocarbon dates are described from a section through Lateglacial and early Flandrian sediments at Llanilid, Mid‐Glamorgan, South Wales. Comparisons between age determinations on the alkali soluble (humic) and alkali insoluble (humin) organic fractions from 12 biostratigraphic horizons reveal the extent of contamination by both older and younger carbon residues. The Llanilid time‐scale suggests that for the Lateglacial, the earliest organic sediments date from around 13 200 yr BP, the early Interstadial Juniperus maximum occurred at ca. 12 400‐12 500 yr BP with a marked decline some 200 years later, the main Betula phase lasted only from ca. 11 700 to 11 400 yr BP and the end of the Interstadial occurred around 11 100 yr BP. The beginning of the Flandrian dates from ca. 10 000 yr BP, the Juniperus maximum occurred approximately 200 years later, the expansion of birch woodland began around 9600 yr BP, while the first hazel arrived in the area at ca. 9300 yr BP. These age determinations are discussed in the context of radiocarbon dates from comparable biostratigraphic horizons in western Britain and the dating of Lateglacial events in the ocean core records from the North Atlantic.

Hydrocarbons generated by pyrolysis of insoluble kerogen-like materials isolated from microbially degraded plant residues

Leaves of trees, leaves and stems of fresh water- and seawater-submerged weeds and marine benthic macroalgae were incubated for long periods of time (2 months to 14.5 yr.) under subaquatic conditions either in fresh water or seawater. The incubation experiments provided light- to dark-brown colored plant residues, from which insoluble organic fractions comparable to kerogen in natural sediments were separated. The kerogen-like materials were isolated by using the same method as usually employed for isolation of natural kerogens. On pyrolysis, the kerogen-like materials produced a series of n-alk-1-enes and n-alkanes with little odd-even carbon-number preference, and various C 19-C 20 acyclic isoprenoid hydrocarbons. These hydrocarbons, except for phytenes and phytadienes, are known to be the major pyrolysis products of natural kerogens. The elemental composition and the chromatographic profile of the pyrolysate hydrocarbons varied according to the type of source material, providing evidence for variation in the structural characteristics of natural kerogens from different depositional environments.

Use of collagenase to purify collagen from prehistoric bones for stable isotopic analysis

The low molecular weight hydrolysis products of the reaction between collagenase and the HCl insoluble organic fraction from modern and well-preserved prehistoric bones have the same stable carbon and nitrogen isotopic compositions and amino acid composition as “collagen” extracted by dissolution in warm dilute acid. The hydrolysis products produced using the collagenase method from some poorly preserved fossil bones have the same amino acid composition as the products produced from modern bones, even though the “collagen” extracted from these bones by the conventional solubility method bears no similarity to modern collagen either in terms of amino acid or isotopic composition. These observations suggest that collagenase can possibly be used to purify a fraction from such poorly preserved prehistoric bones that retains its in vivo isotope ratios, thereby permitting isotopic paleodietary reconstruction for bones that cannot be studied with currently available techniques.