| 摘要: |
| 碳库效应存在影响了14C测年的准确性,制约了利用沉积物在湖泊研究中的应用。本文研究了位于典型西风环流带的新疆博斯腾湖现代碳库效应,并结合同位素地球化学、水化学等方法,探讨了博斯腾湖碳库效应的影响机制。研究结果表明,博斯腾湖最大现代碳库年龄为3535年,最小为现代碳,集中在670-945年。而过去碳库效应集中在1033-2200年。深水区表现为碳库年龄较小且稳定；在入湖口碳库效应最大,富水生植物浅水区碳库效应最小。与过去碳库年龄相比较,现代碳库效应整体表现更为年轻。研究发现,博斯腾湖口受流域外源“死”碳影响,深水区受湖水与大气CO2交换率差异影响,富水生植物浅水区可能受水生植物光合作用影响。此外,核爆效应也对博斯腾湖现代碳库效应产生了影响,可能导致最高约1000年的年代误差。利用深水区pMC平均值与大气碳比活度差值(~18%),得出深水区沉积物存在约846年现代碳库效应,再经核爆效应校正后得出博斯腾湖存在最高约1800年碳库效应。 |
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| Study on the modern 14C reservoir effects in Bosten Lake, Xinjiang, China |
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Du Dingding
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: School of Earth Sciences,East China University of Technology
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| Abstract: |
| The 14C reservoir effect is a significant topic of research because it affects the accuracy of 14C dating and limits the use of sediment in lake studies. However, there is still debate over the mechanisms that influence the carbon reservoir effect, largely due to a lack of investigation into modern carbon reservoir effects. Bosten Lake in Xinjiang, situated in a typical westerly circulation zone, has high sediment concentration and is an ideal location to study this issue due to its significant carbon reservoir effect. However, previous studies on Bosten Lake have primarily focused on past carbon reservoir effects, which are heavily influenced by sediment processes. This study aims to explore the modern 14C reservoir effect of typical freshwater surface sediment in Bosten Lake. By combining 14C dating results with isotopic geochemistry, hydrochemistry, and other methods, the study determined that the maximum modern carbon reservoir age in Bosten Lake is 3535 years, and the minimum is modern carbon, concentrated between 670-945 years. Past carbon reservoir effects were concentrated between 1033-2200 years. The deepwater area exhibited a smaller and more stable carbon reservoir age, while the carbon reservoir effect was highest in the lake inlet and lowest in the shallow water area with abundant aquatic plants. Compared to the past carbon reservoir age, the modern carbon reservoir effect was generally younger. The study found that the Bosten Lake inlet was influenced by external "dead" carbon, the deepwater area was impacted by differences in the exchange rate of lake water and atmospheric CO2, and the shallow water area with abundant aquatic plants may be affected by photosynthesis of aquatic plants. Additionally, nuclear explosion effects also influenced the modern carbon reservoir effect of Bosten Lake, leading to a potential age error of approximately 1000 years. Finally, by correcting the difference between the average pMC value of the deepwater area and the atmospheric carbon activity (about 18%), the study determined that the deepwater sediment in Bosten Lake has a modern carbon reservoir effect of about 846 years, which was further corrected for nuclear explosion effects to determine that the highest 14C reservoir effect in Bosten Lake is about 1800 years. |
| Key words: Bosten lake Modern 14C reservoir effects Variation rules Influencing factor |
