Organic matter sources to the water column and surficial sediments of a marine bay

Abstract

Sediment trap and net plankton samples were collected monthly for a year at three depths in a marine bay (Dabob Bay, Washington). These materials and subsamples from a sediment box core were analyzed for lignin oxidation products as well as elemental and stable carbon isotope compositions. The sediment core was compositionally uniform over its entire 50-cm length. The elemental and lignin compositions of the sediment trap and core samples indicate nitrogen-rich (atomic C : N = 7.5) plankton-derived organic matter mixed with vascular plant debris.At most, vascular plant debris accounts for 10% (nonwinter months) to 35% (winter months) of the total organic carbon in the upper water column (30 m) sediment trap samples and consists predominantly of gymnosperm wood along with some nonwoody gymnosperm tissues and angiosperm woods. Bulk land-derived organic matter in Dabob Bay contains a maximum of 50% vascular plant debris and comprises an average of one-third of the total organic carbon in the sediment trap samples and two-thirds of the total organic carbon in the underlying sediments. Lignin in the sediment trap and core samples shows evidence (from elevated vanillic acid:vanillin ratios) of white-rot fungal degradation before (but not after) introduction to the water column at the study site. Vascular plant debris introduced to the bay has already lost almost half of its initial bulk polysaccharide. Glucose yields are particularly low whereas rhamnose and fucose are obtained in excess of expected yields and must have additional sources.Lignin and neutral sugars together account for ~20% of the total organic carbon in the sediment trap and core samples. Overall, the sediments of Dabob Bay compositionally resemble the gymnosperm wood-rich particulate material introduced to the overlying water column during winter and poorly record the input of plankton and other types of vascular plant debris during nonwinter months.

C/N ratios in a sediment core from Nakaumi Lagoon, southwest Japan. Usefulness as an organic source indicator.

“…This is often the case, with high correlation coefficients for C org. and N total (r > 0.9) reported in the literature (e.g., Hedges et al, 1986Hedges et al, , 1988Martens et al, 1992). Apparent variations in the C/N ratio should be checked when the ratio decreases with decreasing C org.…”

Record of terrestrial organic matter composition in Amazon Fan sediments

“…Hence, gymnosperm and angiosperm nonwoody vascular plant tissues generally yield elevated C/V ratios (0.8 ≥ C/V ≥ 0.1) relative to their wood counterparts (C/V < 0.05). Based on these characteristic distributions, S/V and C/V ratios have been used extensively to differentiate terrigenous sources of sedimentary organic matter (e.g., Hedges et al, 1986aHedges et al, , 1988bGough et al, 1993).…”

“…For example, CuO oxidation analyses of vascular plants have shown lignin compositions to vary predictably among plant types (Hedges and Mann, 1979a;Hedges et al, 1986a;Goñi and Hedges, 1992). These distinctive compositions have been used to discern the sources of vascular plant detritus in a variety of environments (e.g., Hedges and Mann, 1979b;Ugolini et al, 1981;Wilson et al, 1985;Requejo et al, 1986;Hedges et al, 1988b;Goñi and Hedges, 1992;Prahl et al, 1994). In particular, changes in lignin phenol compositions have been used to reconstruct past inputs of vascular land plant materials to lacustrine Ishiwatari and Uzaki, 1987) and marine sediments .…”

Uso Dos Isótopos Estáveis De Carbono, Nitrogênio E Enxofre Em Estudos De Ecologia Costeira

“…Por exemplo, alguns pesquisadores ao se defrontarem com uma composição isotópica fora da faixa esperada, classifi cam o fenômeno como contaminação (Kojima & Ohta 1989), quando na verdade o que ocorre é que a variação da composição isotópica das fontes pode não ter sido considerada completamente. Da mesma forma, Hedges et al (1988) não obtiveram sucesso ao comparar o isótopo de carbono e o teor de lignina na matéria orgânica, e, uma vez que a lignina pode ser atribuída a plantas terrestres sem ambigüidade, isso demonstra que o isótopo de carbono não foi tão efi ciente para se diferenciar matéria orgânica terrestre e marinha no caso estudado. Finalmente, existe a complicação potencial decorrente da diferença entre plantas C 3 e C 4 no ecossistema terrestre, que pode ter levado a erros ao se estimar quantitativamente a entrada de matéria orgânica terrestre no mar (Chikaraishi et al 2007).…”