A molecular biomarker for end-Permian plant extinction in South China

To help resolve current controversies surrounding the fundamental question of synchrony between end-Permian mass extinction on land and in the sea, we examined the marine Permian–Triassic reference section at Meishan (southeastern China) for land-derived molecular degradation products of pentacyclic triterpenoids with oleanane carbon skeletons, diagnostic for the Permian plant genus Gigantopteris. We identified a continuous quantitative record of mono-aromatic des-A-oleanane, which abruptly ends in the main marine extinction interval just below the Permian-Triassic boundary. This taxon-specific molecular biomarker, therefore, reveals in unmatched detail the timing and tempo of the demise of one of the most distinctive Permian plants and provides evidence of synchronous extinction among continental and marine organisms. Parallel reduction in the relative abundance of lignin phenols confirms that aridity-driven extinction was not restricted to Gigantopteris but likely affected the entire wetland flora of the equatorial South China microcontinent.

Lignin phenols as a basis for biopreparations

The content and composition of lignin phenols in plants and soils of latitudinal zones and vertical natural zones of the North Caucasus and Northwest Tien Shan have been studied. The special role of lignin phenols of underground plant organs in the process of humification was revealed. It was shown that the oxidation degree of the biopolymer increases during the transformation of organic matter from living plant tissues to humic acids in soils. The fraction of lignin fragments that remain unchanged during the biotransformation of the polymer in the row plant tissues – fall – litter – soils – humic acids – buried humic acids is calculated. It has also been demonstrated that the biochemical composition of plants has a decisive effect on the structure of humic acids in soils. With the help of quantitative analysis of lignin phenols and 13C NMR spectroscopy, it is proved that lignin of higher plants is involved in the formation of humic acids, both aliphatic and aromatic parts of molecules. The areas of application of lignin phenols in the practice of agriculture and medicine are proposed.

Deglacial records of terrigenous organic matter accumulation off the Yukon and Amur rivers using lignin phenols and long-chain n-alkanes as biomarkers

<p>Anthropogenic climate change has profound impacts on Arctic temperatures, with consequences for Arctic ecosystems and landscapes, and the stability of organic-rich permafrost deposits. When mobilized, these permafrost deposits might release vast amounts of greenhouse gases. We use periods of past rapid warming in the high latitudes as analogues to study the ecological changes and effects on permafrost stability under climate change. We used marine sediment cores from the Bering and Okhotsk Sea continental margins, off the mouths of the Yukon and Amur rivers, to study two types of terrigenous biomarkers, which trace different terrestrial organic carbon (OC) components and transport pathways, and cover the early deglaciation to the early Holocene. The Yukon basin remains within the permafrost-affected region today, whereas the Amur basin changed from being subject to complete permafrost cover during the last glacial to permafrost-free conditions today. </p><p>Vascular plant-derived lignin phenols were analyzed and compared to published n-alkane content data. The carbon- and sediment-normalized contents of the vanillyl phenols (V), syringyl phenols (S), and cinnamyl phenols (C) phenols (Λ8 and Σ8) reflect the content of lignin dominantly transported by river runoff. The C/V and S/V ratios serve to distinguish between woody and non-woody tissues of angiosperms and gymnosperms. The acid to aldehyde ratios of V and S phenols ((Ad/Al)<sub>V</sub> and (Ad/Al)<sub>S</sub>) indicate the degree of lignin degradation. In addition, the ratio of 3,5-dihydroxybenzoic acid to V (3,5Bd/V) likely reflects the wetland extent, while lignin reflects primarily transportation into the marine sediment via surface runoff. In contrast, the n-alkane contents represent primarily terrigenous organic matter eroded from deeper deposits and a second marker for wetland extent via the Paq index. Lignin and n-alkane mass accumulation rates (MAR) can thus be used to reconstruct the mobilization of different carbon pools and the relative timing of the processes leading to their export to the ocean.</p><p>The MAR of biomarkers and the wetland indicators 3,5 Bd/V and Paq start to increase in the Bering Sea sediment during the early deglaciation (19-14.6 ka BP), while no obvious change in lignin MAR in the Okhotsk Sea occurred during this time. We observe distinct peaks of mass accumulation rates, wetland indices and indicators for degradation of lignin (Ad/Al) in both sediment cores during the warm Bølling-Allerød (12.9-14.6 ka BP) and Pre-Boreal (9-11.5 ka BP) intervals, and during the Younger Dryas cold spell (11.5-12.9 ka BP). In contrast, in the Okhotsk Sea, the ratios of S/V and C/V did not change before the Preboreal. </p><p>Our biomarker data suggest that the permafrost in the Yukon basin may have started to be remobilized by inland warming leading to wetland development in the early deglaciation, while the onset of permafrost degradation in the Amur basin occurred during the Preboreal.</p>

Lignin phenols in sediment cores and its indications of degradation and organic carbon sources of the Yantan Reservoir, China

Three sediment cores collected from the Yantan Reservoir, located in the Pearl River, southwest China, were analyzed for lignin phenols, elemental and stable carbon isotopic composition to investigate the variation patterns, vegetation sources, degradation stage, and relative proportions of terrestrial sedimentary organic carbon (OC). Significant temporal and spatial heterogeneity in terrestrial OC burial was indicated by the changes of lignin contents at different depths in different sampling sites: the inlet zone, the central reservoir zone in front of dam and the reservoir bay. The interception impact of upstream dam, the influence of artificial regulation, as well as the role of interzonal recharge made the terrestrial OC burial remains complex in the reservoir. The oxidized lignin signatures showed spatial heterogeneity suggesting active oxidative degradation and demethylation/demethoxy degradation of sedimentary lignin during deposition, especially in the inlet zone. An angiosperm herbaceous tissue and gymnosperm woody tissue contributed the sedimentary lignin. A soil-plankton-plant three-end-member mixing model revealed that soil-derived OC dominated before impoundment and at the early stage of reservoir operation, while the contribution of autochthonous OC began to dominate after gradually aging and eutrophicating of the reservoir. Our study of lignin evolution in reservoir highlights important temporal and spatial reservoir carbon components and their contribution to sedimentary carbon pools, providing new insights into the estimation of organic carbon burial in reservoirs.

Adsorption Study of Lignin Removal from Recycled Alkali Black Liquor by Adsorption Resins for Improved Cellulase Hydrolysis of Corn Straw

Previous studies showed that aromatic compounds such as lignin, phenols, and furans were main inhibitors of cellulase hydrolysis in recycled alkali black liquor (RBL), which should be removed to improve alkali utilization. In this study, three polymeric resins, XAD-4, XAD-16N, and XAD-7HP, were evaluated for their abilities to remove lignin from alkali black liquor recycled at the third time. Adsorption conditions of adsorbent dose and equilibrium time, isotherms, and kinetics were investigated. Of three tested adsorbents, XAD-16N was the most efficient, which can remove 89.84% of lignin after adsorption at an adsorbent-to-solution ratio of 1:4 for 2.5 h. Pseudo-second-order model was efficient to represent XAD-16N and XAD-7HP adsorption kinetics. Adsorption behavior of XAD-4 on RBL was fitted better to Langmuir model, while XAD-16N and XAD-7HP adsorption were more consistent with Freundlich model. The cellulase hydrolysis rate of corn straw treated with RBL after XAD-16N adsorption combined with ozone was 86.89%, which was only 0.89% lower than that of sodium hydroxide combined with ozone treatment. Structure characterization proved that the damage of XAD-16N adsorbed RBL to corn straw was similar to that of sodium hydroxide. It indicated that adsorption was effective in inhibitor removal from RBL to improve alkali utilization.