A study of the formation of high molecular weight compounds during the decomposition of a field diatom population     

E.-L. Poutanen  R.J. Morris 《Estuarine, Coastal and Shelf Science》1983,17(2):189-196

This work has investigated the possible formation of humic and fulvic acids, particularly high molecular weight moieties, in degrading diatom debris. The diatom debris was collected, freshly sedimented, from a well characterized natural field diatom population and allowed to degrade under conditions similar to those found at the sediment-water interface of many marine, organic-rich sediments.Samples of the detritus and overlying water were taken regularly over a period of 4 months and analysed for the presence of humic compounds. In the case of the detrital material, a sequential series of extractions were used. Molecular weight fractionation of the extracted humic material was carried out using Diaflow Ultrafiltration Membranes and two different fractionation methods have been compared. It appears that the choice of method may have an important effect on the determined distribution of the humic material, particularly when humic acid concentrations are low.High molecular weight (> 300 000- > 100 000) humic and fulvic acids were found in all the detrital samples, the content increasing with the period of decomposition. No evidence of any humic material was found in extracts of the living diatoms, the conclusion being that this material had been formed in situ during the degradation of the diatom debris. Most (65–90%) of the humic material was extracted from the detritus using a mild 0·05 m NaOH extraction at room temperature. Fulvic acids comprised approximately 90% of the total 0·05 m NaOH extraction, being composed mainly of either low molecular weight compounds (40–50% < 10000) or high molecular weight compounds (38–48% > 100000). Levels of humic acids were much lower and included a wide range of molecular weight fractions.The relevance of these findings to the possible origin of humic material in certain marine sediments is discussed.  相似文献   

The relationship between fatty acid distributions and bacterial respiratory types in contemporary marine sediments     

R.J. Parkes  J. Taylor 《Estuarine, Coastal and Shelf Science》1983,16(2):173-189

Bacterial communities of different respiratory types were isolated from a marine sediment in a multiple chemostat system in an attempt to obtain bacterial cultures representative of the sediment. The fatty acid distribution of a mixed culture of sulphate-reducing bacteria isolated from this system showed a good correlation with the lipid distribution of the zone of maximum sulphate-reduction activity within the sediment. Both distributions had significant concentrations of C14 : 0, iso and anteiso C15 : 0, C16 : 0, C16 : 1ω7 and C18 : 1ω7. This was in contrast to the lipid profile of Desulfovibrio desulfuricans obtained by batch enrichment, which was dominated by iso C17 : 1ω7 fatty acids and correlated poorly with the sediment. The bacterial community cultured from the sediment was further differentiated according to respiratory types (aerobic, facultative aerobic and facultative anaerobic) by growth in a chemostat under defined conditions. The fatty acid distributions of these communities were sufficiently different to enable the various respiratory types to be recognized by their particular fatty acid composition. Cyclopropyl fatty acids (?17 and ?19) were present in significant levels only in the aerobic bacteria, while the facultative aerobes had significantly higher C18 : 1ω7 than the other cultures and the facultative anaerobic community was the only culture to have significant amounts of C12 : 0. The fatty acid distribution of Loch Eil sediment over the range C12-19 seemed to be predominantly of bacterial origin and were relatively abundant to a depth of 6 cm. The concentration of cyclopropyl fatty acids was highest in the oxidized surface sediments and decreased with depth as anaerobic conditions began to dominate, indicating that these fatty acids may only be indicative of aerobic sedimentary bacteria. In contrast to the fatty acids characteristic of bacteria, those fatty acids in the range C20-30 attributed to a terrestrial input were found in relatively constant concentrations over the whole 0–12 cm depth profile.  相似文献   

Forms and bioavailability of phosphorus associated with natural organic matter     

Zhongqi HE Tsutomu Ohno Barbara J. Cade-Menun M. Susan Erich C. Wayne Honeycutt 《中国地球化学学报》2006,25(B08):259-259

Natural organic matter （NOM） is an important ingredient in soil which can improve physical, chemical, and biological properties of soils and nutrient supplies. In this study, we investigated the spectral features and potential availability of phosphorus （P） in the IHSS Elliott Soil humic acid standard （EHa）, Elliott soil fulvic acid standard Ⅱ （EFa）, Waskish peat humic acid reference （WHa）, and Waskish peat fulvic acid reference （WFa） by fluorescence spectroscopy, FT-IR, solution 31P NMR, 3-phytase incubation and UV irradiation. We observed more similar spectral features between EHa and EFa as well as between WHa and WFa than between the two humic acids or two fulvic acids themselves. Phosphorus in WHa and WFa was mainly present in the orthophosphate form. However, only about 5% was water soluble. After treatment by both UV irradiation and enzymatic hydrolysis, soluble orthophosphate increased to 17% of WHa P, and 10%o of WFa P. Thus, it appears that a large portion of P in Waskish peat humic substances was not labile for plant uptake. On the other hand, both orthophosphate and organic phosphate were present in EHa and EFa. Treatment by both UV irradiation and enzymatic hydrolysis increased soluble orthophosphate to 67% of EHa P and 52% of EFa P, indicating that more P in Elliott soil humic substances was potentially bioavailable. Our results demonstrated that source （soil vs. peat） was a more important factor than organic matter fraction （humic acid vs. fulvic acid） with respect to the forms and lability of P in these humic substances.  相似文献   

Gas-Phase OH Oxidation of Monoterpenes: Gaseous and Particulate Products     

Bo. R. Larsen  Dario Di Bella  Marianne Glasius  Richard Winterhalter  Niels R. Jensen  Jens Hjorth 《Journal of Atmospheric Chemistry》2001,38(3):231-276

Smog chamber experiments have beenconducted in which cyclic monoterpenes were oxidisedin the gas phase by OH. The evolved secondary organicaerosol (SOA) was analysed by LC-MSⁿ and thegas-phase products were analysed by FT-IR. Theconcentrations of the identified compoundscorresponded to carbon mass balances in the range of40%–90%. The identified compounds in the particularphase corresponded to 0.5%–4.2% of the reactedcarbon. The most abundant compounds in SOA fromterpenes with an endocyclic C=C double bond wereC₁₀-keto-aldehydes, C₁₀-keto-carboxylicacids, C₁₀-hydroxy-keto-carboxylic acids, andC₁₀-hydroxy-keto-aldehydes (pinonaldehyde,pinonic acid, hydroxy-pinonic acid isomers, andhydroxy-pinonaldehyde isomers from -pinene;3-caronaldehyde, 3-caronic acid, hydroxy-3-caronicacid isomers, and hydroxy-3-caronaldehyde isomers from3-carene). The most abundant compounds in SOA fromterpenes with an exocyclic C=C double bond wereC₉-ketones, C₉-dicarboxylic acids, andC₁₀-hydroxy-keto-carboxylic acids (nopinone,pinic acid, and hydroxy-pinonic acid isomers from-pinene; sabinaketone, sabinic acid andhydroxy-sabinonic acid isomers from sabinene).Decarboxylated analogues of most of the compounds werepresent in SOA in minor concentrations, such asC₉-keto-carboxylic acids (norpinonic acid,nor-3-caronic acid) and C₈-dicarboxylic acids(norpinic acid, nor-3-caric acid, norsabinic acid). InSOA from limonene, which contains an endocyclic aswell as an exocyclic C=C double bond, the mostabundant compounds were a C₁₀-keto-aldehyde andits oxo-derivative (limononaldehyde and keto-limononaldehyde) together with hydroxy-derivatives of aC₁₀-keto-carboxylic acid (isomers ofhydroxy-limononic acid). Also aC₁₀-keto-carboxylic acid (limononic acid) waspresent together with minor concentrations of aC₉-dicarboxylic acids (limonic acid), itsoxo-derivative (keto-limonic acid), and itsdecarboxylated analogue (norlimonic acid). Mechanisticpathways for the formation of these products, some ofwhich are identified here for the first time, areproposed.  相似文献   

高岭土/胡敏酸复合体对重金属离子吸附解吸实验研究   总被引：2，自引：0，他引：2  

吴平霄  徐玉芬  朱能武  党志 《矿物岩石地球化学通报》2008,27(4)

本文利用高岭土对胡敏酸吸附形成稳定的有机一无机络合物,研究了高岭土／胡敏酸复合体对Cu^2＋、Cd^2＋和Cr^2＋的吸附。结果表明,胡敏酸对高岭土改性后能提高上述三种重金属离子的吸附性能,高岭土／胡敏酸复合体对三种重金属离子的吸附量都随pH值的升高而增加,随离子强度的增加而减小。本文还研究了高岭土／胡敏酸复合体对上述三种重金属离子的吸附动力学,发现吸附过程可用Elovich方程和一级动力学方程进行较好的拟合。  相似文献   

Comparison of binding abilities of fulvic and humic acids extracted from recent marine sediments with UO₂     

C. Munier-Lamy  Ph. Adrian  J. Berthelin  J. Rouiller 《Organic Geochemistry》1986,9(6)

Potentiometric titrations were used to measure conditional stability constants of UO₂²⁺-fulvic acid and UO₂²⁺-humic acid complexes. Both 2:1 and 1:1 COO^-:UO₂²⁺ binding were observed. With decreasing metal concentration (2.5·10⁻⁴-6.25·10⁻⁵ M) increasing amounts of UO₂²⁺ were in the form of 1:1 humate complexes and 2:1 fulvate complexes. Despite the high nitrogen content and the low acidic OH group content, the successive stability constant values were similar to those determined for divalent cations associated with fulvic and humic compounds isolated from soils. Stability constant values increase simultaneously with increasing ionization of the humic (or fulvic) acid polyelectrolytes and with decreasing metal concentration.  相似文献   

Improvement of kerogen structural interpretations based on oxidation products isolated from aqueous solutions     

D. Vitorovi&#x;  A. Ambls  M. Djordjevi&#x; 《Organic Geochemistry》1986,10(4-6)

A detailed investigation of kerogen oxidation products remaining in aqueous solutions after the usual isolation of degradation products by extraction with ether or precipitation, was carried out for the first time in kerogen structural studies. Three shale samples were investigated: Green River shale (type I kerogen), Toarcian shale, Paris Basin (type II), and Mannville shale, Canada (type III). The yields of acids from aqueous solutions were noticeable: 12.98, 15.32 and 22.32%, respectively, based on initial kerogens. Qualitative and quantitative capillary GC/MS analysis showed that the ratios of different kinds of identified acids depended much on the type of precursor kerogen. Some of the acids identified in aqueous solutions have not been found earlier among the degradation products of the same kerogen samples, or were obtained in different ranges and yields. Consequently, slight modifications were suggested of the image on the nature of various types of kerogens based on examination of ether-soluble acids only. Namely, slightly higher proportions of aromatic and alkane-polycarboxylic acids in the total oxidation products of both type I and type II kerogens indicated larger participation of aromatic and alicyclic and/or heterocyclic structures in these two kerogens. On the other hand, for type III Mannville shale kerogen, a somewhat larger share of aliphatic type structures was demonstrated.  相似文献   

Measurement of methanotroph and methanogen signature phosopholipids for use in assessment of biomass and community structure in model systems     

Peter D. Nichols  Carol A. Mancuso  David C. White 《Organic Geochemistry》1987,11(6)

Methanotrophic biomass and community structure were assessed for a soil column enriched with natural gas. An increase in microbial biomass, based on phospholipid ester-linked fatty acids (PLFA), was apparent for the natural gas-enriched column relative to a control column and untreated surface soil. Following GC-MS analyses of the derivatized monounsaturated fatty acids, the major component (22% of the PLFA) of the natural gas-enriched column was identified as 18·1Δ 10c. This relatively novel fatty acid has only been previously reported as a major component in methanotrophs. Its presence in the soil, together with other supportive evidence, implies that this microbial metabolic group makes a large contribution to the column flora. Other microbial groups were also recognized and differences compared between the soils analysed. A recently developed HPLC method for the separation and characterisation of archaebacterial phospholipid-derived signature di- and tetra-ether lipids was used to examine methane-producing digesters. With this technique, methanogenic biomasses of approximately 10¹¹ bacteria per g dry weight of digestor material were determined. Differences between ratios of diether to tetraether phospholipids were apparent for the digestors analysed, though the causes are at this stage unknown. Taken together, these two methods can be used to estimate methanotrophic and methanogenic contributions in both model systems and environmental samples.  相似文献   

The occurrence of bisulfite-aldehyde addition products in fog- and cloudwater     

J. W. Munger  D. J. Jacob  M. R. Hoffmann 《Journal of Atmospheric Chemistry》1984,1(4):335-350

Elevated concentrations of S(IV) and formaldehyde were observed in fog- and cloudwater at sites in California. The highest concentrations (up to 3 mM S(IV) and 0.7 mM CH₂O) were measured at Bakersfield, during a prolonged period of repeated fog. In Bakersfield [S(IV)] generally exceeded [CH₂O], while in the Los Angeles area the reverse was observed. The lowest concentrations of both species were observed at marine and high altitude sites away from local emissions. Equilibrium computations indicate that high concentrations of S(IV) cannot be achieved without the formation of S(IV)-RCHO adducts.  相似文献   

Latitudinal patterns and influencing factors of soil humic carbon fractions from tropical to temperate forests   总被引：3，自引：0，他引：3  

Li Xu  Chunyan Wang  Jianxing Zhu  Yang Gao  Meiling Li  Yuliang Lv  Guirui Yu  Nianpeng He 《地理学报(英文版)》2018,28(1):15-30

Soil humic carbon is an important component of soil organic carbon (SOC) in terrestrial ecosystems. However, no study to date has investigated its geographical patterns and the main factors that influence it at a large scale, despite the fact that it is critical for exploring the influence of climate change on soil C storage and turnover. We measured levels of SOC, humic acid carbon (HAC), fulvic acid carbon (FAC), humin carbon (HUC), and extractable humus carbon (HEC) in the 0–10 cm soil layer in nine typical forests along the 3800-km North-South Transect of Eastern China (NSTEC) to elucidate the latitudinal patterns of soil humic carbon fractions and their main influencing factors. SOC, HAC, FAC, HUC, and HEC increased with increasing latitude (all P<0.001), and exhibited a general trend of tropical < subtropical < temperate. The ratios of humic C fractions to SOC were 9.48%–12.27% (HAC), 20.68%–29.31% (FAC), and 59.37%–61.38% (HUC). Climate, soil texture, and soil microbes jointly explained more than 90% of the latitudinal variation in SOC, HAC, FAC, HEC, and HUC, and interactive effects were important. These findings elucidate latitudinal patterns of soil humic C fractions in forests at a large scale, and may improve models of soil C turnover and storage.  相似文献