Retention of lignin in seagrasses: angiosperms that returned to the sea

Using Curie-point Pyrolysis Gas Chromatography Mass Spectrometry (Py-GCMS) and Direct Temperature-resolved Mass Spectrometry (DT-MS), lignin was detected in highly purified preparations (Milled Wood Lignin = MWL) of various tissues of the seagrasses Zostera marina and Posidonia oceanica. The results indicate that P. oceanica contains more lignin than Z. marina and that roots and rhizomes generally contain more lignin than leaves. It is concluded that the ability to produce lignin is not lost by the angiosperm ancestors of extant seagrasses upon their colonization of the marine environment. Relative lignin abundances in the different tissues appear to be positively correlated with life span. It is suggested that lignification contributes to the longevity of a tissue by protecting it against microbial attack, but that deposition of lignin in seagrasses is restricted to tissues that show limited growth. [KEYWORDS: lignin; seagrass; pathogenic resistance; pyrolysis; gas chromatography; mass spectrometry Pyrolysis mass-spectrometry; zostera-marina; curie-point; discriminant-analysis; fungal degradation; oxidation-products; phenolic-acids; beech wood; growth; decomposition]

Chemical characterization of lignin preparations of fresh and decomposing Spartina anglica by pyrolysis mass spectrometry

In order to determine terrestrial contributions to the organic matter pool in the marine environment, a reliable chemical tracer is required. Lignin, an abundant component of vascular plant tissue is often used as such. In this study the lignin moiety of both fresh and degraded tissue of the model halophyte Spartina anglica was purified and chemically characterized to investigate its suitability as tracer. The study can be split into three parts. In the first part several enzymatic lignin purifications of fresh S. anglica tissue were compared with each other. In the second part pyrolysis gas chromatography mass spectrometry was applied to analyse untreated and on-line methylated milled wood lignin preparations. The previous characterizations of the lignin moiety of S. anglica were used in the third part to monitor modifications in the chemical composition induced by natural aerobic decomposition in the field. The temperature at which lipids were extracted from the original tissue was not critical, although low temperatures improved the purification to some extent. For enzymatic purification of lignin the use of a polysaccharidase turned out to be the most important prerequisite. The use of a protease did not have much influence on the lignin residue. After 2 yr of aerobic decomposition, the lignin character of untreated S. anglica tissue was no longer identifiable with direct temperature-resolved mass spectrometry, but it still could be retrieved in the residue obtained after enzyme treatment. With continuing decomposition the chemical structure of the lignin moieties became partly modified. The very complicated spectra obtained after longer decomposition periods suggest the formation of a heterogeneous organic fraction, probably representing "humic substances". The gradual loss of lignin characteristics in the litter makes its suitability as tracer for terrestrial material in a complex mixture of substances doubtful, at least with the analytical technique applied in this study. [KEYWORDS: lignin; Spartina anglica; halophyte; litterbag decomposition; pyrolosis; mass spectrometry; TMAH Salt-marsh sediments; discriminant-analysis; organic-matter; early diagenesis; flash pyrolysis; alterniflora;biodegradation; lignocellulose; polymers; wood]

Assessment of the molecular composition of particulate organic matter exchanged between the Saeftinghe salt marsh (southwestern Netherlands) and the adjacent water system

In this study the chemical composition of seston, transported by tidal water between an estuarine salt marsh and the adjacent water system, was assessed. The analytical techniques used are Pyrolysis in combination with Gas Chromatography and/or Mass Spectrometry. Interpretation of the Py-MS data was aided by discriminant analysis. The presented results indicate that throughout the year a dominant refractory fraction is present in the seston, but that seasonal additions can be distinguished, Apart from this seasonal pattern, differences between ebb and flood can be visualized by the use of discriminant analysis. During summertime, flood seston is enriched with lipids and recently synthesized polysaccharides, while during the rest of the year the flood tide samples contain more (remains of) lignin and polysaccharides than their ebb tide counterparts, The lignin markers comprise only fragments with extremely altered (reduced) character, These results, which highlight the molecular composition of the exchanged seston but do not offer exact quantitative budget estimations, provide no evidence for export of lignin-rich particulate halophytic material from the marsh to the water system. On the contrary, based on seston compositions, the water system seems to supply lignin-rich particles to the marsh during a considerable part of the year. [KEYWORDS: salt marshes; tidal exchange; particulate organic matter; pyrolysis; gas chromatography; mass spectrometry Chromatography-mass-spectrometry; ems-dollard estuary analytical pyrolysis; oxidation-products; marine-sediments; microcrystalline cellulose; spartina-alterniflora; discriminant-analysis; south-carolina; buried woods]

Chemical characterization of lignin preparations of fresh and decomposing Spartina anglica by pyrolysis mass spectrometry

In order to determine terrestrial contributions to the organic matter pool in the marine environment, a reliable chemical tracer is required. Lignin, an abundant component of vascular plant tissue is often used as such. In this study the lignin moiety of both fresh and degraded tissue of the model halophyte Spartina anglica was purified and chemically characterized to investigate its suitability as tracer. The study can be split into three parts. In the first part several enzymatic lignin purifications of fresh S. anglica tissue were compared with each other. In the second part pyrolysis gas chromatography mass spectrometry was applied to analyse untreated and on-line methylated milled wood lignin preparations. The previous characterizations of the lignin moiety of S. anglica were used in the third part to monitor modifications in the chemical composition induced by natural aerobic decomposition in the field. The temperature at which lipids were extracted from the original tissue was not critical, although low temperatures improved the purification to some extent. For enzymatic purification of lignin the use of a polysaccharidase turned out to be the most important prerequisite. The use of a protease did not have much influence on the lignin residue. After 2 yr of aerobic decomposition, the lignin character of untreated S. anglica tissue was no longer identifiable with direct temperature-resolved mass spectrometry, but it still could be retrieved in the residue obtained after enzyme treatment. With continuing decomposition the chemical structure of the lignin moieties became partly modified. The very complicated spectra obtained after longer decomposition periods suggest the formation of a heterogeneous organic fraction, probably representing "humic substances". The gradual loss of lignin characteristics in the litter makes its suitability as tracer for terrestrial material in a complex mixture of substances doubtful, at least with the analytical technique applied in this study. [KEYWORDS: lignin; Spartina anglica; halophyte; litterbag decomposition; pyrolosis; mass spectrometry; TMAH Salt-marsh sediments; discriminant-analysis; organic-matter; early diagenesis; flash pyrolysis; alterniflora;biodegradation; lignocellulose; polymers; wood