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Limitation of lignin derivatives as biomarkers of land derived organic matter in the coastal marine sediments

Pempkowiak Janusz

Oceanologia

2020

No. 62 (3)

374--386

Lignin oxidation products (vanillyl, syringil and cummaryl phenols), and δ13C were measured in a variety of land and marine samples collected in Inner Puck Bay – dominated by marine vascular plants, small river run-off, and shallow bottom, and in Gdańsk Bay – characterized by large river run-off, small marine vascular plants population, and the average depth exceeding euphotic zone. Both study areas are parts of the Gdańsk Basin, Southern Baltic. Typical δ13C values (δ13C  = -28‰) and both composition and concentrations of lignin phenols were measured in samples originating from land. Small, yet easily measurable amounts of lignin phenols were found in marine vascular plants biomass (Σ8 = 90 µg/100 mg organic matter). The biomass was characterized by exceptionally high δ13C values (-12‰). No lignin phenols and typical δ13C values (-22‰) were measured in marine phytoplankton biomass. δ13C and both composition and content of lignin phenols in organic matter of surface sediments collected in the study area fall in the range marked by the end members. The proportion of land derived organic matter calculated using lignin phenols, or δ13C in Gdańsk Bay were comparable, while in Puck Bay they differed substantially. It was concluded that a) in areas with substantial bottom coverage with vascular plants the two end members approach, usually employed to establish the contribution of organic matter sources, is insufficient, b) organic matter originating from three sources: riverine, phytoplankton, and vascular plants contribute to sedimentary organic matter in Puck Bay with the respective proportion 30:40:30.

The comparison analyses of nonlinear calculations of flat plate systems with and without shear reinforcement

Dadayan T., Karapetyan L., Avagyan H.

Zeszyty Naukowe Politechniki Częstochowskiej. Budownictwo

2018

Z. 24 (174)

60-65

Linear, nonlinear and test comparison analyses of flat plate slabs with shear reinforcement are presented in the article. Analyses of slabs with and without shear reinforcement by nonlinear simulations are introduced. The calculations of slabs without and with 0.16 m eccentricities were performed. For analyses finite element method were used. Design models of flat slab with column by “Lira SAPR” software were carried out. After the calculations whole results with experimental investigations were compared. The comparison analyses were shown, that presence of shear reinforcement far increase the capacity of slabs. Furthermore, the presence of shear reinforcement depends on eccentricity increases the axial force approximately 25%. Moreover, the difference between tests and nonlinear analyses results are about 6.4%.

W artykule przedstawiono liniowe, nieliniowe i doświadczalne analizy porównawcze płaskich płyt stropowych ze zbrojeniem na ścinanie. Przeprowadzono analizy płyt ze wzmocnieniem i bez zbrojenia z wykorzystaniem symulacji nieliniowych. Wykonano obliczenia płyt bez mimośrodów i z mimośrodami 0,16 m. Do analiz wykorzystano metodę elementów skończonych. Wykonano modelowanie płaskiej płyty ze słupem za pomocą oprogramowania "Lira SAPR". Po zakończeniu obliczeń porównano wyniki z badaniami eksperymentalnymi. Analizy porównawcze wykazały, że obecność zbrojenia na ścinanie znacznie zwiększa zdolność płyt do przenoszenia obciążeń. Ponadto obecność zbrojenia na ścinanie zależy od mimośrodowości, a siła osiowa wynosi około 25%. Co więcej, różnica pomiędzy testami i wynikami analiz nieliniowych wynosi około 6,4%.