Assessment of two grainsize methods for peat sediments and their paleoenvironmental significance: the Yueliangwan Peatland in northeast Asia

Abstract

Grainsize is an important indicator in paleoenvironmental research. Over the past few decades, different pretreatment methods have been proposed for grainsize determination of peat sediments. Assessing the reliability of the grainsize measurements is critical to ensure the paleoenvironmental significance represented by different grainsize components. In this study, using peat sediments from the Yueliangwan peatland in northeast Asia, the effects of two pretreatment methods on grainsize measurement were compared. It was found that these two pretreatment methods on peat sediments produced grainsize features with totally different parameters and distribution characteristics. Grainsize method 1, which used a hydrogen peroxide water bath treatment, did not reflect accurate results for grainsize in peat sediments. Grainsize method 2, which used muffle furnace combustion, does reflect the true results because the organic matter, such as plant residues, spores and pollen, is totally removed. The presence of this stubborn organic matter in peat samples greatly disturbs the accuracy of grainsize measurements, and the reliability of grainsize measurements can be affected by the presence of stubborn organic matter. Based on the grainsize grade-standard deviation analysis using method 2, the East Asian Winter Monsoon evolutionary history in northeast Asia during the Little Ice Age (1300–1750 CE) was reconstructed and divided into three stages: the strengthening stage (1346–1425 CE), the strongest stage (1425–1525 CE) and the weakening stage (1525–1725 CE).

KEY POINTS

1. Comparisons and assessments are presented for two different pretreatment methods for grainsize measurement of peat deposits.

2. The grainsize features of peat deposits obtained through the combustion method are more accurate.

3. The grainsize features of peat deposits obtained through the H₂O₂ method do not eliminate the influence of stubborn organic matter.

4. The East Asian Winter Monsoon variations in northeast Asia were driven by Siberian High and Arctic sea ice.

Keywords:

• grainsize
• analysis method assessments
• paleoenvironment reconstruction
• The East Asian Winter Monsoon
• northeast Asia
• peatland

Acknowledgements

The authors are grateful to Professor John P. Smol from Queens University Canada for his constructive and thoughtful suggestions, which significantly improved the quality of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article. Original samples can be accessed from the corresponding author upon reasonable request.

Additional information

Funding

This study was financially supported by the National Natural Science Foundation of China [Grant No. 42371099] and supported by the Science and Technology Development Plan of Jilin Province [Grant No. YDZJ202201ZYTS471], and ‘the Fundamental Research Funds for the Central Universities’ [Grant Nos. 2412023YQ006, 2412020FZ005].