Abstract
Increasing concentrations of dissolved organic carbon (DOC) have been observed in coastal ecosystems worldwide over the past decade, and tight coupling of the carbon (C) and phosphorus (P) biogeochemical cycle has been recognized in aquatic ecosystems. However, there is still no consensus regarding the potential effects of DOC loading on sediment P release. In a 2-month mesocosm experiment, we tested the effects of DOC enrichment on sediment P release in six glass aquariums. Two treatments were set: Control (without sodium acetate (Na(CH3COO)) addition) and Na(CH3COO) addition (equivalent to 5 mg C L−1). The results showed the following: 1) DOC loading stimulated sediment P mobilization and release, as indicated by increases in the labile P recorded for 7-cm-deep sediment using diffusive gradients in thin films, the flux of P across the sediment–water interface, and the total P concentrations in the overlying water; and 2) stimulated alkaline phosphatase activity, increased P-solubilizing bacteria proportion, and decreased dissolved oxygen concentration were likely the primary mechanisms behind the DOC-stimulated sediment P mobilization and release. These results provide insight into the promotion of sediment P release induced by C addition. Further studies investigating the quantitative relationships between DOC loadings and P release are needed to fully elucidate the coupled roles of C and P, especially those based on large-scale field investigations with broader C forms and loadings.
Highlights
Dissolved organic carbon (DOC) is the most active carbon pool in marine ecosystems
The total inorganic carbon (TIC) levels were significantly higher in the +Carbon treatment than in the Control (p < 0.001)
In terms of flux of P (Flux-P) across the sediment–water interface (SWI), no obvious difference appeared between pre-C (0.01 μg cm2 s−1) and post-C addition (0.01 μg cm2 s−1) for the Control, while a noticeable increase from 0.01 to 0.02 μg cm2 s−1 was traced for + Carbon treatment (Figure 2)
Summary
Dissolved organic carbon (DOC) is the most active carbon pool in marine ecosystems. Notably, there has been a massive rise in DOC loading in many coastal and marginal oceans (Sawicka et al, 2021; Huntington and Wieczorek, 2021). P release was found to increase (Khoshmanesh et al, 1999; Anderson, 2018), decrease (Stutter et al, 2020), or be unaffected (Diana et al, 2013) after the input of DOC. These conflicting results suggest that there is considerable uncertainty regarding the impact of DOC loading on sediment P release. There remains a need to more clearly elucidate the responses of sediment P cycling to increasing DOC loading and clarify the seemingly conflicting conclusions about the trends in P release responses to C loading
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
