| 摘要: |
| 过去百年来, 全球环境变化已经从全新世自然因素影响为主发展到以人类活动影响为主的人类世时期。人类世时限特征和全球界线层型剖面和点位(GSSP)是科学界正在解决的难题。文章基于先前多年研究的东北大兴安岭摩天岭泥炭环境演变记录, 进一步分析其多氯联苯(PCBs)和化石孢粉记录, 并结合已有的Pb含量、210Pb比活度和稳定铅同位素(207Pb/206Pb)等多指标进行综合分析。结果表明: 高分辨率的综合地球化学记录均指示了自1950年以来人类活动对区域环境的影响作用在显著增强; 通过与国际地层委员会人类世工作组确定的候选剖面东北四海龙湾玛珥湖沉积物进行比较, 识别出人类世下边界的最佳选择是20世纪50年代。研究通过我国典型雨养泥炭记录的过去百年来环境污染历史重建与比较, 为获取人类世全球同步信号提供了新的证据支持。 |
| 关键词: 泥炭 环境污染 人类活动 多氯联苯 铅同位素 我国东北 |
| DOI：10.7515/JEE2024025 |
| CSTR：32259.14.JEE2024025 |
| 分类号: |
| 基金项目:广东省基础与应用基础研究基金项目（2025A1515011992）；国家自然科学基金项目（41971113） |
| 英文基金项目: |
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| Anthropocene environmental evolution history recorded by typical ombrotrophic peat bog in China |
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BAO Kunshan1，LIN Zhanyi1，SHEN Ji2，WANG Guoping3
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1. School of Geography, South China Normal University, Guangzhou 510631 , China ；2. School of Geography and Ocean Science, Nanjing University, Nanjing 210023 , China ；3. Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102 , China
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| Abstract: |
| Background, aim, and scope In the past hundred years, the global environmental change has developed from the influence of natural factors in the Holocene to the influence of human activities in the Anthropocene. The characteristics of the time limit of the Anthropocene and the global boundary stratotype profile and point (GSSP) are the problems that are being solved by the scientific community. An ombrotrophic bog is a domed peatland in which the surface peat layers are hydrologically isolated from the influence of local ground and surface waters, and has been proved to be a good continental geochemical archive of the past environmental changes. The aim of this study is to provide a multi-proxy record of environmental evolution history by a typical ombrotrophic peat bog in China, aiding the clarification of the timing of the Anthropocene. Materials and methods This study was based on the previous investigated peat records of Motianling in the Great Hinggan Mountains in Northeast China. Motianling, located in the upper reaches of the Daheigou Stream northeast of A’ershan City, Hinggan League, Nei Mongol Autonomous Region, is the highest peak of the Great Hinggan Mountains (geographic coordinates: 47°22ʹN, 120°39ʹE; elevation: 1500—1700 m). The sampling site is located on the north slope of Motianling (with a slope of approximately 30°), about 2600 m southwest of Songye Lake. In October 2008 and June 2009, six peat cores (labeled as MP1, MP2, MP3, MP4, MP5, MP6) were collected using a Russian corer and directly excavated trench profiles, with lengths (40—78 cm) covering the entire peat deposit. The peat cores (MP1, MP2, MP3) were dated by 210Pb and 137Cs techniques and the chronologies were calculated using the constant rate of 210Pb supply model (CRS), thereby establishing a sedimentary chronological framework for the past 200 years. All six peat cores were analyzed for ash content, dry bulk density, and water content. For cores MP1 and MP3, polychlorinated biphenyls (PCBs) were analyzed at 1 cm or 2 cm intervals, and core MP2 was analyzed for fossil pollen at 4 cm intervals to reconstruct local ecological conditions and the plant communities that formed the peat. These parameters were comprehensively compared them with previous indicators such as Pb content, 210Pb radioisotope activity, and stable lead isotopes (207Pb/206Pb). Results Physicochemical properties of the peat (i. e., dry bulk density, ash content, total organic carbon) as well as other proxies reported elsewhere before have indicated its ombrotrophic character in the upper sections and minerotrophic character in the lower sections. PCBs were detected in both peat profiles from the Motianling peatland with mean concentrations of (10.07±8.34) ng/g and (23.72±17.47) ng/g, respectively. In both profiles, the total PCB content showed an increasing trend with decreasing depth and PCB accumulation was significantly higher after than before 1950. A total of 45 palynological taxa were identified from the peat samples, including 24 woody plant genera, 15 terrestrial herb genera, 2 aquatic vascular plant genera, and 4 fern spore genera, along with the aquatic bryophyte genus Riccia. Based on the percentage changes of major pollen types and the results of CONISS cluster analysis, the pollen spectrum was divided into three pollen zones. Discussion These high-resolution comprehensive geochemical and palaeoecological records of the ombrotrophic bog indicated a significant increase in the impact of human activities on the regional environment since 1950. By comparing with the candidate profiles, Sihailongwan Maar Lake in Northeast China determined by the Anthropocene Working Group of the International Stratigraphy Commission, the best choice for identifying the lower boundary of the Anthropocene was in the 1950s. Conclusions This study provides new evidence support for obtaining the global synchronization signal of the Anthropocene through the reconstruction and comparison of the environmental pollution history recorded by the China’s typical rain fed peat records over the past century. Recommendations and perspectives Peatland studies are presenting a thriving development trend and provide a broad suite of information on the occurrence of ecological conditions and anthropogenic disturbances, especially for missing long-term monitoring data in remote regions. Therefore, peatlands, especially the ombrotrophic bogs play an important role in the study of environmental evolution in the Anthropocene |
| Key words: peat environmental pollution anthropogenic impact PCBs Pb isotopes Northeast China |
