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BGC-02  Biological carbon pump
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Impact of sediment resuspension on POM properties in the water column revealed by AA molecular indicators
Hossen Shipan* , State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China
Zhuo-Yi Zhu, School of Oceanography, Shanghai Jiao Tong University, Shanghai 200030, China
Sheikh AftabUddin, Institute of Marine Sciences, University of Chittagong, Chittagong-4331, Bangladesh
You-You Hao, State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China
Li-Yang Yang, Fujian Provincial Engineering Research Center for High-value Utilization Technology of Plant Resources, College of Environment and Safety Engineering, Fuzhou University, Fuzhou, Fujian, PR China |
Sediment resuspension is a common phenomenon that impact on marine biogeochemistry and ecosystem in the coastal environments, yet its effect on the particulate organic matter in the water column remains an important topic for carbon cycles and ecosystem sustainability. In this work we conducted field investigations to Aojiang Estuary and adjacent Dinghai Bay in 2020, covering summer (July), autumn (October) and winter (January), where intensive bivalves aquaculture takes place on the tidal flat. We found that concentration of particulate organic carbon (POC), particulate nitrogen (PN) and total hydrolysis particulate amino acids (THPAA) were higher during July and October than January but generally individual D-AA (%) were significantly higher in January. According to IsoSource analysis, the sediment resuspension was significantly higher during October (45%; bivalves harvest) and January (37%; laver harvest) than during July (21%; bivalves culture). In contrast, in July the phytoplankton fraction gave its maximum contribution to OC% (65%) in near shore area (where bivalves aquaculture takes place), when compared to January (23%) and October (33%). Amino acids molecular indicates were applied to reveal the POM properties and positive value of Degradation Index (DI) was observed in July (0.18 to 1.27) and negative value of DI was observed during January (-0.92 to -0.39) and October (-0.90 to -0.50). This indicates the less degradation of POM in July and more degradation in January and October, consistent with resuspension seasonality. During January and October, Gly (%) with GABA (%) was also significantly higher during these two seasons than in July. The advanced degradation POM in autumn and winter indicates less carbon release from POM and a dilution of materials availability for heterotroph utilization in the water column, whereas in summer the good POM freshness well corresponded to local aquaculture activities, supporting the growth of bivalves. Our results have implications for addressing the influence of sediment resuspension on the water quality and ecosystem sustainability in the coastal environment. Keywords: Particulate organic matter, Sediment resuspension, Coastal aquaculture, Stable isotope, Amino acids, Aojiang estuary |
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