Winter mixing accelerates decomposition of sedimentary organic carbon in seasonally hypoxic coastal seas

Wei, Lin; Cai, Pinghe; Shi, Xiang; Cai, Wei‐Jun; Liu, Wei; Hong, Qingquan; Wu, Tong; Bai, Yan; Cheng, Peng; Sun, Zhenyu

doi:10.1016/j.gca.2021.11.003

Cited by 18 publications

(8 citation statements)

References 48 publications

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“…This finding is supported by recent field measurements by L. Wei et al. (2021). In summer, the DO in the bottom water is lower and the porewater advection transporting oxygen into deeper sediments is weaker due to the milder hydrographic environment (in terms of wind‐waves and wave‐current interaction) than that in winter.…”

Section: Discussionsupporting

confidence: 87%

Water Oxygen Consumption Rather Than Sediment Oxygen Consumption Drives the Variation of Hypoxia on the East China Sea Shelf

et al. 2022

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Section: Discussionsupporting

confidence: 87%

Water Oxygen Consumption Rather Than Sediment Oxygen Consumption Drives the Variation of Hypoxia on the East China Sea Shelf

et al. 2022

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“…All sampling took place during the stratified summer season, when water temperatures in the SBC are greatest and NO 3 - concentrations are lowest (Brzezinski et al ., 2013; McPhee-Shaw et al ., 2007). Fluxes of chemical species from sediment change seasonally (Nielsen, Risgaard-Petersen, and Banta, 2017; Smyth et al ., 2018), and nutrient fluxes from marine sediment have been demonstrated to increase with increasing temperatures in summer (Boynton et al ., 2018) as well as with increased mixing and resuspension in winter (Wei et al ., 2022). Sediments in the SBC may have the capacity for increased remineralization rates during winter, when wave energy is higher and more organic material is delivered to the coast due to storms, but these are also periods of high NO 3 - availability when contributions of NH 4 + are less important (Aguilera and Melack, 2018; Brzezinski et al ., 2013).…”

Section: Discussionmentioning

confidence: 99%

Examining the Potential of Sandy Marine Sediments Surrounding Giant Kelp Forests to Provide Recycled Nutrients for Growth

Lowman

Hirsch

Brzezinski

et al. 2023

Journal of Coastal Research

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Lowman, H.E.; Hirsch, M.E.; Brzezinski, M.A., and Melack, J.M., 2023. Examining the potential of sandy marine sediments surrounding giant kelp forests to provide recycled nutrients for growth. Journal of Coastal Research, 39(3), 442–454. Charlotte (North Carolina), ISSN 0749-0208.Permeable marine sediments are biogeochemically active and may contribute dissolved nutrients to support primary production in coastal regions. This study examined the potential of permeable marine sediments near giant kelp forests in the Santa Barbara Channel, California as a source of ammonium (NH4+) to the overlying water column to support the observed growth of kelp during summer months when nitrate availability is low. Several nearshore sites located in coastal California in <20 m water depth were sampled for porewater nutrient concentrations, flushing rates, and nutrient fluxes in addition to diel fluctuations in nutrient concentrations of the overlying water column. Time-series analyses of porewater temperatures indicate that porewater flushed to a depth of 15 cm approximately every two hours, and mean NH4+ concentrations of porewater at these depths was 40 µM. The results of flow-through bioreactor incubations indicate that the top 2 cm of sediment are a net source of dissolved nitrogen to the overlying water column and are capable of supplying from 0.05 to 0.90 mmol NH4+ m–2 day–1. Diel water sampling demonstrates that kelp forests may be exposed to NH4+ concentrations greater than 1 µM for multiple hours (four–eight) over a day. These measured reservoirs and exchange rates of NH4+ suggest sandy marine sediments provide a significant source of nitrogen to the water column and may help meet the nitrogen demand by giant kelp during summer in the Santa Barbara Channel.

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“…Secondly, strong oxygen exposure might be largely linked to impeded OC preservation (Sobek et al, 2009;Wang et al, 2018;Wei et al, 2022). In the bloom season, the high cyanobacteria-derived OC mineralization rates would lead to a relatively anaerobic environment by consuming oxygen through the water column (Cai et al, 2014;Yan et al, 2019).…”

Section: Contributors For Stronger Oc Loss In Shallow Subtropical Lakesmentioning

confidence: 99%

“…However, oxygen accumulated from the photosynthesis of phytoplankton on the lake surface could compensate for the oxygen consumption by cyanobacteria-derived OC mineralization and prevent the water from hypoxia condition (DO < 2 mg L −1 ). Also, strong water mixing disturbed by wind in summer seasons maintains an oxidizing environment (Jalil et al, 2018) suitable for continuous OC mineralization in shallow aquatic ecosystems (Wang et al, 2018;Wei et al, 2022). Therefore, high oxygen exposure and the sustained oxidizing environment during the whole year guarantee the highly effective OC loss through the water column in shallow subtropical lakes.…”

Section: Contributors For Stronger Oc Loss In Shallow Subtropical Lakesmentioning

confidence: 99%

Seasonal constraints on the burial of organic carbon in the eutrophic Lake Taihu

He²,

Jiali³

et al. 2023

Front. Earth Sci.

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Eutrophication alters the function of lake ecosystems through phytoplankton blooms and is a major contributor to organic carbon (OC) burial in lakes worldwide. Although Lake Taihu is notable for its severe eutrophication yet low OC burial, why cyanobacteria-derived OC is ineffectively buried in the lake is unknown. Because seasonal hydrological and ecological dynamics in eutrophic lacustrine ecosystems would significantly modify the preservation and degradation behaviors of OC, seasonal variations in paired particulate samples from both the water column and surface sediment are critical in evaluating cyanobacteria-derived OC burial. In this study, we present the steroid results of water and sediments collected from Meiliang Bay in Lake Taihu across cyanobacteria-bloom and decay seasons (from May 2018 to June 2019) to investigate constraints on the seasonal burial of autochthonous and allochthonous OC. The results indicate that cyanobacteria contribute a considerable amount of OC to the water body in the cyanobacterial bloom season, while terrestrial OC becomes the main contributor during the cyanobacterial decay season. Although OC degradation occurs throughout the water column, substantially more OC degradation was observed at the water-sediment interface. The extensive degradation of OC in the bloom season eventually reverses the seasonal distribution characteristics of particulate OC in the water column, leading to less accumulation of OC under the background of higher cyanobacteria-derived OC input. The combined effect of OC bioavailability, temperature, oxygen exposure, and more importantly microorganism activities, accounts for much higher OC degradation rates in the bloom season. Similar phenomena were observed in subtropical shallow lakes with high primary productivity, suggesting that eutrophication might have a limited influence on OC burial when compared to other factors related to OC degradation.

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Winter mixing accelerates decomposition of sedimentary organic carbon in seasonally hypoxic coastal seas

Cited by 18 publications

References 48 publications

Water Oxygen Consumption Rather Than Sediment Oxygen Consumption Drives the Variation of Hypoxia on the East China Sea Shelf

Water Oxygen Consumption Rather Than Sediment Oxygen Consumption Drives the Variation of Hypoxia on the East China Sea Shelf

Examining the Potential of Sandy Marine Sediments Surrounding Giant Kelp Forests to Provide Recycled Nutrients for Growth

Seasonal constraints on the burial of organic carbon in the eutrophic Lake Taihu

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