Yields Of Lignin Phenols Research Articles

Floodplain influence on dissolved organic matter composition and export from the Mississippi—Atchafalaya River system to the Gulf of Mexico

Comparisons of the concentrations and compositions of dissolved organic matter (DOM) between the lower Mississippi River (MR) and its distributary, the Atchafalaya River (AR), indicated a strong influence of floodplains on DOM in the AR. Concentrations of dissolved organic carbon (DOC), lignin phenols, amino acids, neutral sugars, and chromophoric DOM (CDOM) absorption coefficients were higher in the AR than in the MR. Significantly lower syringyl to vanillyl phenol ratios (S : V) in the AR indicated substantial contributions from gymnosperms (e.g., Taxodium distichum). The lowest S : V values in the AR were measured during maximal litterfall in October‐November when yields of lignin phenols were highest. Lower spectral slope coefficients (S275–295) in the AR were indicative of relatively high‐molecular‐weight CDOM. Yields and compositions of amino acids and neutral sugars indicated DOM in the AR was more bioavailable than in the MR. Nitrogen removal in the floodplain was in part responsible for the significantly lower concentrations of total dissolved nitrogen (TDN) in the AR. Seasonal variability in DOM composition was greater in the AR. About 35% of the DOC and > 44% of the lignin phenols, amino acids, and neutral sugars exported from the Mississippi‐Atchafalaya River system was carried by the AR, thereby revealing the important role of the AR in DOM export from the river system. DOC export from rivers was predominantly controlled by water discharge. The long‐term (1996–2010) average DOC export from the Mississippi‐Atchafalaya River system was 2.70 Tg yr−1 (MR: 1.75 Tg yr−1; AR: 0.95 Tg yr−1), accounting for 0.8–1.1% of global riverine DOC export.

Impact of extreme drought and the Three Gorges Dam on transport of particulate terrestrial organic carbon in the Changjiang (Yangtze) River

[1] To investigate the impact of extreme drought and the Three Gorges Dam on organic carbon (OC) exported by the Changjiang (Yangtze) River, suspended particulate matter samples collected in 2003 (normal year) and 2006 (drought year) from the middle and lower reaches of the mainstream of the river were analyzed for elemental carbon, stable carbon isotope, and lignin-phenol yields. In comparison with suspended particulate matter samples collected in 2003, the 2006 samples showed elevated organic carbon content [OC%: (1.91 ± 0.43)% and (0.95 ± 0.07)% respectively in 2006 and 2003], higher autochthonous OC [Chl-a/OC: (20.68 ± 9.03)mg/g OC and (7.33 ± 2.97)mg/g OC in 2006 and 2003], decreased lignin yields [Λ8: (0.90 ± 0.41)mg/100 mg OC and (1.91 ± 0.33)mg/100 mg OC in 2006 and 2003], and higher degradation state [(Ad/Al)v: 0.44 ± 0.21 and 0.27 ± 0.028 in 2006 and 2003]. These differences may be explained by changes in grain composition and concentration of the suspended particulate matter, which were caused by the lower water discharge and sediment load in 2006. Extreme drought and impoundment of water by the Three Gorges Dam not only affected the signatures and fluxes of terrestrial OC, but hid the seasonal signal of riverine OC. The impact of the Three Gorges Dam was more significant in the middle reach than in the lower reach. Lakes and tributaries in the lower Changjiang River supplied great amounts of terrestrial OC to the mainstream. In the drought year, the supplement of water provided by the lower lakes and tributaries was more significant. The absolute magnitude of reduction of terrestrial OC in the Changjiang River during drought and Three Gorges Dam influence (2006) would have severely affected the local carbon cycle and would have influenced the global carbon cycle to some extent.

Characterization of Lignin by Gas Chromatography and Mass Spectrometry Using a Simplified CuO Oxidation Method

An efficient and high-throughput method to characterize lignin in environmental samples using alkaline CuO oxidation and capillary gas chromatography with mass detection is presented. Monomeric lignin phenols released during oxidation were selectively extracted using a polymer-based solid phase sorbent rather than liquid phase extraction. Sample size and matrix were found to influence lignin phenol yields. Increasing the sample size to an organic carbon content ≥1.5 mg of C minimizes phenol oxidation losses, and the addition of glucose as a sacrificial carbon source helped minimize oxidation losses in samples with <5 mg of organic carbon.

Terrigenous organic matter sources and reactivity in the North Atlantic Ocean and a comparison to the Arctic and Pacific oceans

Lignin phenol concentrations and compositions in suspended particulate and dissolved organic matter (POM and DOM) were determined in samples from several locations and depths in the western North Atlantic Ocean. POM lignin phenol concentrations were ∼2-fold lower than previous measurements in the Pacific Ocean, but represented up to 28% of the total lignin phenols in the water column. Carbon-normalized yields of lignin phenols and δ 13C measurements of POM indicate that up to half of the suspended material in deep water is of terrigenous origin and appears to enter the ocean via atmospheric deposition. This finding emphasizes the need for future research into aerosol compositions and fluxes into the oceans. In contrast to POM, DOM lignin phenol concentrations were ∼2-fold higher in the Atlantic, with more than two thirds in the high-molecular weight (HMW; > 1 kDa) fraction. Elevated concentrations of dissolved lignin phenols in North Atlantic Deep Water (NADW) indicated that 10–16% of annual fluxes of terrigenous DOM from Arctic rivers could be entrained during NADW formation. The percentage of lignin phenols in the HMW fraction decreases progressively from the Arctic to Atlantic to Pacific Oceans, reflecting an increasing diagenesis of terrigenous DOM. The average residence time of lignin phenols in the Atlantic is ∼ 35 years. Terrigenous DOC accounts for 1–2% of the DOC in surface and deep waters of the North Atlantic.

Sources of particulate organic matter in rivers from the continental usa: lignin phenol and stable carbon isotope compositions

The origins and forms of particulate organic matter (POM) suspended in rivers are major considerations in assessing how fluvial materials integrate landscape and climate properties and ultimately record these characteristics in marine sedimentary deposits. We examined the elemental, stable carbon isotope and lignin-phenol compositions of well-characterized samples of suspended POM collected from rivers draining the south central United States. The atomic C/N ratios of 17 fine-grained samples (∼11 ± 2, n = 17) are similar to those reported worldwide for texturally similar soil and riverine POM. The corresponding δ 13C values vary from −18.5 to −26.4‰, in patterns that correspond to the relative abundances of C3 and C4 plants in the drainage basins, and hence to temperature and hydrologic patterns. Lignin-phenol yields from 12 samples indicate input of angiosperm-rich plant materials in distributions that also reflect upstream climate and vegetation. The lignin associated with these plant remains has been substantially degraded, as is typical of soil organic matter. The mass- and surface-area-normalized organic carbon contents of the river-borne POM also correspond to drainage basin properties in patterns characteristic of soils. These results indicate that highly degraded soil organic matter is a major component of fine-grained POM transported by rivers of the central US. The Mississippi River currently discharges “heavy” (δ 13C ≈ −20‰) lignin-poor POM. The isotopic composition of this organic matter is difficult to distinguish from marine plankton remains in fine-grained sediments of the northern Gulf of Mexico, whose isotopic compositions have been previously interpreted to broadly indicate limited offshore transport of terrigenous organic matter.

Contribution of vascular-plant carbon to surface sediments across the coastal margin of Cyprus (eastern Mediterranean)

Elemental carbon and nitrogen and lignin-phenols were measured in sediments (whole and fractionated) collected from the coast of Cyprus (eastern Mediterranean) in 1997, to determine the sources, fate and distribution of vascular plant-derived organic matter in a system with virtually no river inputs. There was a significant increase in percent fines (<63 μm) in sediments with increasing distance offshore, reflecting the effects of hydrodynamic sorting processes. Although there were no significant differences between the mean total organic carbon (TOC) percentage of whole sediment (0.8±0.2%) and the <63 μm fraction (1.0±0.3%), mean lignin-phenol yields ( Λ) for whole sediments at all stations (0.11±0.07) were significantly higher than in the <63 μm fraction (0.02±0.01). The Λ values ranged from 0.09 to 0.72 and from 0.01 to 0.05 in whole sediment and the <63 μm fraction, respectively. Mean ratios of vanillic acid/vanillin (Ad/Al) v, indicative of the amount of oxidative degradation of the lignin component, were significantly higher in the <63 μm fraction (0.31±0.11) than whole sediment (0.23±0.10). The range of S/V (0.37–0.72) and C/V (0.02–0.06) ratios for both sediment types were within the range of ratios found in the tissues of the three dominant seagrasses ( Cymodocea nodosa, Halophila stipulaceae and Posidonia oceanica), S/V (0.42–1.85) and C/V (0.02–0.08). High syringyl/vanillyl (S/V) ratios (indicative of angiosperm tissues) were found in sediments across all stations along the transect, indicating that seagrass-derived lignin was transported to at least 6 km offshore. Higher (Ad/Al) v ratios in offshore fine particles compared to nearshore whole sediments suggested that there was subaqueous oxidative degradation of lignin which occurred during transport of fine particles across the Cyprus margin. Although biodegradation is likely to be an important mechanism for lignin decay, the high transparency of the ultraoligotrophic waters of Cyprus may have also allowed for photooxidation of lignin-phenols, a process less likely to occur in turbid coastal waters receiving high riverine inputs.

Experimental early-stage coalification of a peat sample and a peatified wood sample from Indonesia

Experimental coalification of a peat sample and a buried wood sample from domed peat deposits in Indonesia was carried out to examine chemical structural changes in organic matter during early-stage coalification. The experiment (125°C, 408 atm lithostatic pressure, and 177 atm fluid pressure for 75 days) was designed to maintain both lithostatic and fluid pressure on the sample, but allow by-products that may retard coalification to escape. We refer to this design as a geologically open system. Changes in the elemental composition, and 13C NMR and FTIR spectra of the peat and wood after experimental coalification suggest preferential thermal decomposition of O-containing aliphatic organic compounds (probably cellulose) during early-stage coalification. The elemental compositions and 13C NMR spectra of the experimentally coalified peat and wood were generally similar to those of Miocene coal and coalified wood samples from Indonesia. Yields of lignin phenols in the peat and wood samples decreased following experimental coalification; the wood sample exhibited a larger change. Lignin phenol yields from the experimentally coalified peat and wood were comparable to yields of lignin phenols from Miocene Indoesian lignite and coalified wood. Changes in syringyl/vanillyl and p-hydroxy/vanillyl ratios suggest direct demethoxylation as a secondary process to demethylation of methoxyl groups during early coalification, and changes in lignin phenol yields and acid/aldehyde ratios point to a coupling between demethoxylation processes and reactions in the alkyl side chain bonds of the α-carbon in lignin phenols.

Elemental and major biochemical changes across an oxidation front in a relict turbidite: An oxygen effect

The elemental and major biochemical compositions of the relict f-turbidite sampled in two cores from the Madeira Abyssal Plain were determined. This fine-grained, distal sequence occurs at ca. 9 m core depth and includes a surficial oxidized horizon defined by a distinct color change. Oxygen diffused downward through sediments above this interface and in ca. 10 kyr destroyed 80% of the organic substances that below the front had survived degradation in the presence of porewater sulfate for ca. 140 kyr. These deposits provide an opportunity to establish the extent and selectivity of oxic sedimentary degradation under natural conditions without the usual complications of bioturbation and varying sources or sedimentation rates. In both cores, a sample from the upper oxidized layer was compared to two samples from the underlying unoxidized layers. The unoxidized sequences of both turbidities contained 0.93–1.02 wt% organic carbon (OC) and 0.10–0.11 wt% total nitrogen (TN). Approximately 20% of the initial OC and 40% of the initial TN remained in the oxidized horizons, with a consequent decrease in atomic C/N ratio from ca. 11 to ca. 5. All samples gave very low yields of lignin phenols and comparable OC-normalized yields of total aldoses and amino acids, and indicated predominantly marine organic matter (OM) and nonselective oxic degradation of these biochemical classes. Compositions of individual aldoses and amino acids generally were also similar in surface and deep sediments, except that the oxidized horizons yielded markedly elevated (3–5X) percentages of nonprotein amino acids. This study clearly demonstrates that prolonged exposure to OZ can lead to organic matter alteration which is far more extensive than that obtained with sulfate alone. In comparison to early diagenesis, however, alteration of the measured biochemicals was largely nonselective. Such oxidation reactions could control the distribution and composition of organic matter in slowly accumulating continental rise and deep-ocean environments.

Elemental and major biochemical changes across an oxidation front in a relict turbidite: An oxygen effect

The elemental and major biochemical compositions of the relict f-turbidite sampled in two cores from the Madeira Abyssal Plain were determined. This fine-grained, distal sequence occurs at ca. 9 m core depth and includes a surficial oxidized horizon defined by a distinct color change. Oxygen diffused downward through sediments above this interface and in ca. 10 kyr destroyed 80% of the organic substances that below the front had survived degradation in the presence of porewater sulfate for ca. 140 kyr. These deposits provide an opportunity to establish the extent and selectivity of oxic sedimentary degradation under natural conditions without the usual complications of bioturbation and varying sources or sedimentation rates.In both cores, a sample from the upper oxidized layer was compared to two samples from the underlying unoxidized layers. The unoxidized sequences of both turbidities contained 0.93–1.02 wt% organic carbon (OC) and 0.10–0.11 wt% total nitrogen (TN). Approximately 20% of the initial OC and 40% of the initial TN remained in the oxidized horizons, with a consequent decrease in atomic C/N ratio from ca. 11 to ca. 5. All samples gave very low yields of lignin phenols and comparable OC-normalized yields of total aldoses and amino acids, and indicated predominantly marine organic matter (OM) and nonselective oxic degradation of these biochemical classes. Compositions of individual aldoses and amino acids generally were also similar in surface and deep sediments, except that the oxidized horizons yielded markedly elevated (3–5X) percentages of nonprotein amino acids. This study clearly demonstrates that prolonged exposure to OZ can lead to organic matter alteration which is far more extensive than that obtained with sulfate alone. In comparison to early diagenesis, however, alteration of the measured biochemicals was largely nonselective. Such oxidation reactions could control the distribution and composition of organic matter in slowly accumulating continental rise and deep-ocean environments.

Diagenetic trends of lignin phenols in Mahakam Delta coals: correlation between laboratory thermal maturation and natural samples

Changes in the general structure of the lignin-derived polymers in a series of increasingly mature, huminite-rich coals from the Mahakam Delta have been investigated by various analytical techniques. The coal series reveals a general reduction in the proportion of oxygen-substituted aromatic carbons as determined by CPMAS 13C NMR, the relative yield of phenol during flash pyrolysis/GC and by the chemical characterisation of lignin phenols, benzoic and hydroxybenzoic acids from CuO oxidation. Several U.S. coals were also analyzed for their lignin phenols composition for comparison. The trends in the yields of lignin phenols from the Mahakam Delta coals were compared with those determined previously from artificially matured wood specimens. It appears that laboratory simulation can predict to some extent the chemical compositional changes taking place in lignin polymers during natural coalification. Thermal (geochemical) degradation plays an important role in the diagenetic alteration of lignin polymer over geological time. The precursors of lignin phenols can survive into the subbituminous rank but are rare or absent above this rank. This is apparently a general characteristic of the coalification process irrespective of the depositional setting or lignin-type. The data from coals in conjunction with our earlier studies on the kinetics of wood pyrolysis imply that lignin phenols might be used as a qualitative palaeovegetation indicator, and possibly a palaeoclimatic marker at least up to the subbituminous rank.

Sources of sedimentary humic substances: vascular plant debris

A modern Washington continental shelf sediment was fractionated densimetrically using either an organic solvent, CBrCl 3, or aqueous ZnCl 2. The resulting low density materials (<2.06 g/ml) account for only 1% of the sediment mass but contain 25% of the sedimentary organic carbon and 53% of the lignin. The C/N ratios (30–40) and lignin phenol yields ( Λ = 8) and compositions indicate that the low density materials are essentially pure vascular plant debris which is slightly enriched in woody ( versus nonwoody) tissues compared to the bulk sediment. The low density materials yield approximately one-third of their organic carbon as humic substances and contribute 23% and 14% of the total sedimentary humic and fulvic acids, respectively. Assuming that the lignin remaining in the sedimentary fraction is also contained in plant fragments that yield similar levels of humic substances, then 50% and 30% of the total humic and fulvic acids, respectively, arise directly from plant debris. Base-extraction of fresh and naturally degraded vascular plant materials reveals that significant levels of humic and fulvic acids are obtained using classical extraction techniques. Approximately 1–2% of the carbon from fresh woods and 10–25% from leaves and bark were isolated as humic acids and 2–4 times those levels as fulvic acids. A highly degraded hardwood yielded up to 44% of its carbon as humic and fulvic acids. The humic acids from fresh plants are generally enriched in lignin components relative to carbohydrates and recognizable biochemicals account for up to 50% of the total carbon. Humic and fulvic acids extracted directly from sedimentary plant debris could be responsible for a major fraction of the biochemical component of humic substances.