| 03 Aug 2026
A paired marine-fluvial modern pollen dataset from the Bohai Sea and its inflowing rivers, China
Abstract. Modern marine pollen records can be interpreted reliably only when the main source-to-sink processes between terrestrial vegetation, rivers, and marine depocentres are documented by comparable modern data. Here, we present and quality-assess a paired marine-fluvial pollen dataset for the Bohai Sea, China, consisting of 430 marine surface-sediment samples and 104 fluvial surface-sediment samples from 16 major inflowing rivers. The dataset includes sample coordinates, water depth for marine stations, river and regional identifiers, pollen and spore counts, pollen concentrations, and grain-size parameters. In total, 104 pollen and spore morphotypes were identified. Marine assemblages are dominated by arboreal pollen, especially Pinus (mean 59 %), whereas nearshore and river-influenced settings contain higher proportions of herbaceous taxa, particularly Chenopodiaceae/Amaranthaceae-type (mean 14 %), Artemisia, and Poaceae. Redundancy analysis after variance-inflation-factor screening indicates that water depth is the strongest retained predictor of marine pollen composition (λ1/λ2 = 0.303), followed by geographic position and sediment texture. In river samples, geographic position, water discharge, and pollen concentration together explain 20.53 % of the compositional variance. Along the 0–35 m depth interval, arboreal pollen and Pinus increase with water depth, whereas herbaceous taxa decrease, providing an internally consistent modern analogue for distinguishing nearshore fluvial influence from more distal aeolian influence. The dataset is intended primarily as a reusable calibration and quality-assessment resource for palaeoenvironmental studies in the Bohai-Yellow Sea region. The archived data are available at the National Tibetan Plateau Data Center (TPDC; Li et al., 2026; https://doi.org/10.11888/Paleoenv.tpdc.303516).
The manuscript by Li et al., submitted to Earth System Science Data (ESSD), presents a very interesting and relevant study that contributes to improving the interpretation of marine pollen sedimentary sequences. The main conclusions highlight the importance of core location, particularly in shallow marginal seas such as the study area, for reliably interpreting the pollen signal.
Pollen records from shallow marginal seas can provide information about changes in water depth rather than solely reflecting changes in terrestrial vegetation. This is because both pollen sources and sediment recruitment mechanisms differ between fluvial and near-shore environments and more offshore settings, where pollen transport by wind may become increasingly important. The study provides a very useful paired marine–fluvial pollen dataset that, in my opinion, deserves publication in ESSD after some minor revisions, which I list below.
Lines 18–19 – Could you also mention pollen and spore percentages?
Lines 26–27 – Do you refer specifically to an increase in pollen percentage or to an increase in pollen concentration?
Line 37 – Please add “and surface and deeper oceanic currents”.
Lines 59–66 – Are there no previous studies in the Bohai Sea region comparing terrestrial pollen sequences with marine pollen sequences? Such comparisons would provide another way to improve the interpretation of the marine pollen records from the Bohai Sea.
Figure 1 legend – Please explain the abbreviations used for the “Marine samples”.
Table 1 – Please enlarge the characters, as they are currently too small to read comfortably.
Lines 171–173 – Were the samples mounted in a mobile medium that allows the pollen grains to rotate, thereby facilitating their identification?
Lines 251–253 – Please add the reference to Naughton et al. (2007)*. This study also shows a decrease in pollen concentration from the coast towards the sea.
Figure 4 – The characters in the legends are too small. Please enlarge them.
Line 376 – Please replace “Within this interval, AP and Pinus percentages increase significantly with water depth, whereas…” with “Pinus percentages increase significantly with water depth, whereas…”. The AP pollen percentages are strongly dominated by the Pinus pollen percentages, as shown by the statistical analyses. In contrast, Quercus and Betulaceae pollen percentages, which represent the two other most dominant arboreal taxa, decrease with water depth.
Lines 419–422 – Please define the abbreviations “P/A” and “PB” in “PB/NAP”.
Line 427 – MIS 2 includes the Last Glacial Maximum. Please rephrase this sentence to make this point clear.
Line 428 – Please replace “MD982194” with “MD98-2194”.
Lines 425–432 – At what distance from the shore and at what water depth are cores DGKS9602 and MD98-2194 located? If these cores are from considerably deeper locations than 35 m, and if the river mouths remained relatively far from the cores during periods of low sea level, it would be difficult to interpret the statement that “ In core DGKS9602, P/A and PB/NAP ratios were used to infer changing shoreline distance, with lower ratios during MIS 2 and the Last Glacial Maximum and higher ratios during warmer high-sea-level intervals (Zheng et al., 2011). The MD982194 record similarly shows negative relationships between herbaceous pollen, freshwater algae, and sea level, whereas bisaccate taxa such as Pinus and Tsuga increase during interglacial or interstadial stages (Zheng et al., 2013)..”
This relationship could instead reflect changes in terrestrial vegetation associated with cold and warm climatic conditions. Indeed, cold climates, low sea-level stands, and an increased contribution of herbaceous vegetation are generally closely coupled and may therefore produce similar pollen signals. Please provide additional information on the locations and water depths of the cores and discuss whether changes in terrestrial vegetation/climate could explain the observed pollen patterns.