Intense hydrolytic enzyme activity on marine aggregates and implications for rapid particle dissolution

Smith, David C.; Simon, Meinhard; Alldredge, Alice L.; Azam, Farooq

doi:10.1038/359139a0

Cited by 912 publications

(856 citation statements)

References 26 publications

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“…Multiple alternate deep DOC sources have been proposed, which might alter DOC Δ 14 C values at depth, including hydrothermal DOC, chemosynthesis, and particle solubilization [Hansman et al, 2009;McCarthy et al, 2011;Smith et al, 1992]. If any of these processes were in fact significant, this would result in source heterogeneity consistent with the mismatch between our model results in surface versus deep ocean.…”

Section: Doc Cycling Using Molecular Size-age Distributions: a Modelisupporting

confidence: 69%

Pacific carbon cycling constrained by organic matter size, age and composition relationships

et al. 2016

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Marine dissolved organic carbon (DOC) is a major global carbon reservoir, yet its cycling remains poorly understood. Previous work suggests that DOC molecular size and chemical composition can significantly affect its bioavailability. Thus, DOC size and composition may control DOC cycling and radiocarbon age (via Δ 14 C). Here we show that DOC molecular size is correlated to DOC Δ 14 C in the Pacific Ocean. Our results, based on a series of increasing molecular size fractions from three depths in the Pacific, show increasing DOC Δ 14 C with increasing molecular size. We use a size-age distribution model to predict the DOC and Δ 14 C of ultrafiltered DOC. The model predicts both large and small surface DOC with high Δ 14 C and a narrow range (200-500 Da) of low Δ 14 C DOC. Deep model offsets suggest different size distributions and/or Δ 14 C sources at 670-915 m. Our results suggest that molecular size and composition are linked to DOC reactivity and storage in the ocean.

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Section: Doc Cycling Using Molecular Size-age Distributions: a Modelisupporting

confidence: 69%

Pacific carbon cycling constrained by organic matter size, age and composition relationships

et al. 2016

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“…Another pathway that has the potential to impact the stoichiometry of sinking POM is bacterial degradation. It has been shown that the rapid decrease of sinking particulate matter with depth is partly associated with degradation processes by particleattached bacteria (Smith et al, 1992;Ploug and Grossart, 2000). However, production rates of free-living and particle-associated bacteria were not significantly different in the high CO 2 treatments throughout the experiment (Hornick, unpublished data).…”

Section: Temporal Development Of Element Stoichiometrymentioning

confidence: 99%

Ocean Acidification-Induced Restructuring of the Plankton Food Web Can Influence the Degradation of Sinking Particles

et al. 2018

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Ocean acidification (OA) is expected to alter plankton community structure in the future ocean. This, in turn, could change the composition of sinking organic matter and the efficiency of the biological carbon pump. So far, most OA experiments involving entire plankton communities have been conducted in meso-to eutrophic environments. However, recent studies suggest that OA effects may be more pronounced during prolonged periods of nutrient limitation. In this study, we investigated how OA-induced changes in low-nutrient adapted plankton communities of the subtropical North Atlantic Ocean may affect particulate organic matter (POM) standing stocks, POM fluxes, and POM stoichiometry. More specifically, we compared the elemental composition of POM suspended in the water column to the corresponding sinking material collected in sediment traps. Three weeks into the experiment, we simulated a natural upwelling event by adding nutrient-rich deep-water to all mesocosms, which induced a diatom-dominated phytoplankton bloom. Our results show that POM was more efficiently retained in the water column in the highest CO 2 treatment levels (>800 µatm pCO 2 ) subsequent to this bloom. We further observed significantly lower C:N and C:P ratios in post-bloom sedimented POM in the highest CO 2 treatments, suggesting that degradation processes were less pronounced. This trend is most likely explained by differences in micro-and mesozooplankton abundance during the bloom and postbloom phase. Overall, this study shows that OA can indirectly alter POM fluxes and stoichiometry in subtropical environments through changes in plankton community structure.

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“…Dissolution appears to be the least likely ex planat io n for the removal of mar ine collo ids from the wa ter colu mn. Hydrolytic e nzymes have been assumed to re nder aggregates (> 0.5~m) soluble (Smith et at.. 1992), but if dissol ut ion was the dominant mechanism for removing mari ne colloids from the water column, it would be difficullto exp lain why particle numbe rs increase with decreasing silt .…”

Section: Lt]mentioning

confidence: 99%

Lipid class and carbohydrate concentrations in marine colloids

1998

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Intense hydrolytic enzyme activity on marine aggregates and implications for rapid particle dissolution

Cited by 912 publications

References 26 publications

Pacific carbon cycling constrained by organic matter size, age and composition relationships

Pacific carbon cycling constrained by organic matter size, age and composition relationships

Ocean Acidification-Induced Restructuring of the Plankton Food Web Can Influence the Degradation of Sinking Particles

Lipid class and carbohydrate concentrations in marine colloids

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