We used accelerator mass spectrometry (AMS) 14C‐dated sediments of the Holocene basal supratidal flat to upper tidal flat facies in 11 cores on the southern Yangtze delta plain to reconstruct relative sea levels of 8.5–8.0 cal ka BP. Three cores were further AMS 14C dated and used to examine the evolution of sedimentary geomorphological environments in response to the rapid sea‐level rise during the early to mid‐Holocene. Results demonstrate relative sea‐level rise of around 30 mm a−1 from 8.5 to 8.3 cal ka BP and around 10 mm a−1 from 8.3 to 8.0 cal ka BP. Retrogradation from supratidal to lower tidal flat environments occurred in response to the rapid sea‐level rise at 8.5–8.3 cal ka BP, and aggradation from middle to upper tidal flat occurred at 8.3–7.9 cal ka BP. Further retreat of the tidal flat at 7.9–7.2 cal ka BP implies a mean sea‐level rise rate exceeding 5 mm a−1 at this time. We suggest that the rapid relative sea‐level rise during 8.3–8.5 cal ka BP and subsequent slower rise caused drastic changes in the coastal zone and that these changes are key phenomena for understanding the coastal response to future sea‐level rise.

No abstract

No abstract

No abstract

Abstract. Dimethyl sulfide (DMS), dimethylsulfoniopropionate (DMSP) and dimethyl sulfoxide (DMSO) were measured at the Boknis Eck Time Series Station (BE, Eckernförde Bay, SW Baltic Sea) during the period February 2009–December 2018. Our results show considerable interannual and seasonal variabilities in the mixed-layer concentrations of DMS, total DMSP (DMSPt) and total DMSO (DMSOt). Positive correlations were found between particulate DMSP (DMSPp) and particulate DMSO (DMSOp) as well as DMSPt and DMSOt in the mixed layer, suggesting a similar source for both compounds. The decreasing long-term trends, observed for DMSPt and DMS in the mixed layer, were linked to the concurrent trend of the sum of 19′-hexanoyloxyfucoxanthin and 19′-butanoyloxy-fucoxanthin, which are the marker pigments of prymnesiophytes and chrysophytes, respectively. Major Baltic inflow (MBI) events influenced the distribution of sulfur compounds due to phytoplankton community changes, and sediment might be a potential source for DMS in the bottom layer during seasonal hypoxia/anoxia at BE. A modified algorithm based on the phytoplankton pigments reproduces the DMSPp : Chl a ratios well during this study and could be used to estimate future surface (5 m) DMSPp concentrations at BE.