摘要
由细菌产生的支链甘油二烷基甘油四醚类化合物(brGDGTs),是示踪过去气候环境变化的重要工具。然而,目前关于此类生物标志物的研究主要集中在基于其不同组分相对分布的气候代用指标,关于其总体含量的影响因素还少有研究。这限制了对于地质记录中brGDGTs含量气候指示意义以及brGDGTs指标季节性的合理解读。本研究调查了中国大范围表土中的brG-DGTs含量,并分析了其与环境因子(包括干旱指数、土壤pH和温度)的关系。结果显示,在全国范围内brGDGTs含量与干旱指数具有最强的相关性,而在不同区域brGDGTs含量均与干旱指数存在中等或较强正相关,但与pH值或温度的相关性不稳定,说明土壤湿度可能是现代表土中brGDGTs含量的主控因素。因此,地质记录中brGDGTs含量的波动可能反映了过去的干湿环境变化。另外,研究结果也表明,土壤中brGDGTs古温度代用指标的季节性,可能不仅包括通常认为的温度的季节性变化,也会受湿度(降水)的季节性变化所影响。
Branched glycerol dialkyl glycerol tetraethers(brGDGTs)produced by microorganisms such as bacteria are important tools for reconstructing past climatic and environmental changes.However,previous works on brGDGTs mainly focus on various proxies based on their distributions,whereas environmental controls on their concentration remains unclear.This hampers our proper understanding on the climatic significance of brGDGT concentration in geological records as well as the seasonality of brGDGT proxies.This study investigated brGDGT concentration in surface soils in different regions of China and analyzed its correlations with environmental factors.The aims were to:1)Explore environmental controls on soil brGDGT concentration,2)Verify whether soil brGDGT concentration can be used as a paleoclimatic proxy,and 3)Clarify the seasonal bias of brGDGT-based paleotemperature proxies in soils.Totaling 273 natural soils were collected during 5 fieldtrips from 5 regions including:the Chinese Loess Plateau and its surroundings,North China to Northeast China,South China,the Shandong Peninsula,and the Northeast Tibetan Plateau.The correlations between brGDGT concentration and aridity index(AI),soil pH,and mean annual air temperature(MAAT)were analyzed.For the whole surface soil dataset,brGDGT concentration showed stronger correlations with AI and soil pH(r=0.81 and-0.74,respectively)than that with MAAT(r=0.10).For the 5 different regions,brGDGT concentration all correlated positively with AI and the correlations were strong or moderate(0.94>r>0.42).On the other hand,the correlations with pH or MAAT were generally weaker and not stable.Specifically,brGDGT concentration correlated negatively with soil pH with r ranging from-0.17 to-0.75,except for a positive correlation(r=0.98)for soils collected from the Shandong Peninsula,while negatively with MAAT with r ranging from-0.12 to-0.94,except that no correlation(r=0.02)was observed for soils collected from the Chinese Loess Plateau and its surroundings.The strongest and most consistent correlations between brGDGT concentration and AI across regions and the whole dataset indicate that soil moisture is the controlling factor for brGDGT production in surface soils.Therefore,we propose that variations in brGDGT concentration in geological records,such as loess-paleosol sequences,can potentially be used to indicate past drying and wetting events.Moreover,our results imply that the seasonal bias in brGDGT-based paleo proxies,traditionally believed to reflect the seasonality of temperature,can also be influenced by seasonal changes in soil moisture(precipitation).
作者
王欢业
苗瑞
卢红选
赵增浩
蔡泽园
盛维娟
刘卫国
Wang Huanye;Miao Rui;Lu Hongxuan;Zhao Zenghao;Cai Zeyuan;Sheng Weijuan;Liu Weiguo(State Key Laboratory of Loess Science,Institute of Earth Environment,Chinese Academy of Sciences,Xi’an 710061,Shaanxi,China;University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《地理科学》
北大核心
2025年第8期1646-1656,共11页
Geographical Science
基金
国家自然科学基金项目(42122021)
国家重点研发计划项目(2023YFF0804300)
中国科学院青年创新促进会会员项目(2019403)资助。
关键词
土壤
brGDGTs
气温
古环境
干旱指数
指标季节性
soil
brGDGT concentration
air temperature
paleoclimate
aridity index
proxy seasonality
