College of Geographic Science, Hunan Normal University, Changsha 410081, PR China.
College of Geographic Science, Hunan Normal University, Changsha 410081, PR China.
Sci Total Environ. 2021 Nov 10;794:148801. doi: 10.1016/j.scitotenv.2021.148801. Epub 2021 Jun 30.
Lake sediments are the products of soil erosion and are strongly influenced by climate variability, particularly extreme meteorological events. Sediment organic carbon (SOC) can reflect environmental changes that affect sediment transport. However, the response of SOC chronological records to major meteorological events is relatively unknown. This study explored the chronological regularity of SOC and verified its variations using major historical meteorological events. Based on three sediment profiles with a depth of 230 cm at the Yuan River entrance to the West Dongting Lake (Hanshou entrance), the SOC chronology was reconstructed by employing the sedimentation rates calculated by Cs and Pb. The sedimentary environment then was interpreted via comparisons and quantitative analysis. The grain distribution and the S-shaped distribution of SOC reflected the general deposition regularity of organic carbon in lake sediments, which gradually stabilized with depth. The average sedimentation rates based on Cs and Pb were 1.310 and 1.319 cm a, respectively. Accordingly, SOC records covered the past 76 years via dating (0-100 cm), during which the SOC content first increased and subsequently stabilized. By comparing the data with the occurrence of 11 major historical meteorological events, we found that SOC generally increased after these events. Moreover, the frequent occurrence of meteorological events stabilized the SOC content. Severe floods had a greater impact on SOC content than severe droughts, causing SOC to change by up to 20.24% and 8.77%, respectively. Our findings suggest that major historical meteorological events can verify SOC chronological records, thereby highlighting their significant impacts on organic carbon variations in sediments.
湖泊沉积物是土壤侵蚀的产物，强烈受到气候变异性的影响，特别是极端气象事件的影响。沉积物有机碳（SOC）可以反映影响沉积物运输的环境变化。然而，SOC 年代记录对主要气象事件的响应相对未知。本研究探讨了 SOC 的年代规律性，并利用主要历史气象事件验证了其变化。基于西洞庭湖沅江河口（汉寿河口）三个深度为 230 厘米的沉积物剖面，通过 Cs 和 Pb 计算的沉积速率来重建 SOC 年代记录。然后通过比较和定量分析来解释沉积环境。颗粒分布和 SOC 的 S 形分布反映了有机碳在湖泊沉积物中一般的沉积规律，其随着深度逐渐稳定。基于 Cs 和 Pb 的平均沉积速率分别为 1.310 和 1.319 cm a。因此，通过定年（0-100 厘米），SOC 记录覆盖了过去 76 年，期间 SOC 含量先增加后稳定。通过将数据与 11 次主要历史气象事件的发生进行比较，我们发现 SOC 通常在这些事件之后增加。此外，气象事件的频繁发生稳定了 SOC 含量。洪水对 SOC 含量的影响大于干旱，导致 SOC 分别变化 20.24%和 8.77%。我们的研究结果表明，主要历史气象事件可以验证 SOC 年代记录，从而突出它们对沉积物中有机碳变化的重要影响。
