The Mu Us dune field in China has become a focal region for research of the prevention and control of desertification.Agricultural practices in this area have been modernized in recent years,evidenced by the developme...The Mu Us dune field in China has become a focal region for research of the prevention and control of desertification.Agricultural practices in this area have been modernized in recent years,evidenced by the development of Center Pivot Irrigation(CPI)farmlands.However,the impacts of CPI farmlands on combating desertification remain poorly understood.This study chose the southeastern part of the Mu Us dune field as a study area to investigate the variations of CPI farmlands from 2009 to 2018 and the influencing factors.The results showed growth trends in both the number and the area of these CPI farmland units over the period.The areas of meso-and micro-scale CPI farmland units stabilized over time to mainly 0-0.2 km2 and 0.2-0.4 km2,respectively;Topography,temperature,and geological substratum were preliminarily identified as the major natural factors driving the development of the CPI farmlands.Within the context of varied stakeholders,the potential for soil erosion,and damage to natural vegetation,the current study suggests that strict management of CPI farmland is required through effective long-term planning and land-use policies.The results of this study can assist in realizing the sustainable development of agriculture and its ecological significance in dune field areas.展开更多
毛乌素沙地保存着晚第四纪以来的多种沉积序列,记录了过去数十万年以来的古气候变化信息.文章通过地层对比与OSL测年相结合,建立了毛乌素沙地中部乌审旗地区发育厚11.6m的MLL黄土剖面245 ka B.P.以来的年代框架,并对地层划分、沉积特征...毛乌素沙地保存着晚第四纪以来的多种沉积序列,记录了过去数十万年以来的古气候变化信息.文章通过地层对比与OSL测年相结合,建立了毛乌素沙地中部乌审旗地区发育厚11.6m的MLL黄土剖面245 ka B.P.以来的年代框架,并对地层划分、沉积特征及其古环境指示意义进行了分析.结果表明：MLL地层剖面是与黄土高原地区相似但又具有特殊性的黄土-古土壤序列,同时也明显不同于沙漠-黄土过渡带常见的古风成砂-古土壤序列.该剖面出露了L3以上连续稳定的黄土-古土壤沉积层以及地表风沙层FS.L1的上下砂黄土层之间夹有一个弱发育古土壤层,S1和S2分别具有两个古土壤复合层,紧接S1、S2a、S2b及L1b底部发育有连续稳定的钙结核淀积层.地表风沙层下部有薄层弱发育砂质土层,未见明显的全新世中期古土壤（S0）发育.L1、S1与S2具有与典型黄土相似的一般特征,可作为MLL剖面地层划分以及年龄控制的标志层.MLL剖面黄土层和古土壤层中的砂质成分含量均较高,＞63 μm砂粒含量分别达到了57.11％和44.77％,但在全剖面未见埋藏古风成砂层存在.MLL剖面CaCO3含量的旋回变化与黄土高原地区一致,黄土层CaCO3含量显著高于古土壤层,发育较好的S1b、S2b中CaCO3含量分别只有0.13％、1.31％.MLL剖面不同层次之间的磁化率对比不明显,黄土磁化率值与古土壤相差极小.245 ka B.P.以来强劲的冬季风作用和风尘堆积,使毛乌素沙地中部一直处于鄂尔多斯高原“风沙高原”的控制之下,即使在暖湿气候条件下的间冰期,粘化层风化淋滤作用也相对较弱.展开更多
毛乌素沙地位于东亚季风边缘区,对于气候变化响应敏感.基于沙地的侵蚀-堆积关系,在侵蚀作用为主的沙地西北部和中部很难找到沉积相对连续且分辨率较高的地层剖面,因此已有的末次冰期古气候环境研究多集中于堆积作用为主的沙地东南缘的...毛乌素沙地位于东亚季风边缘区,对于气候变化响应敏感.基于沙地的侵蚀-堆积关系,在侵蚀作用为主的沙地西北部和中部很难找到沉积相对连续且分辨率较高的地层剖面,因此已有的末次冰期古气候环境研究多集中于堆积作用为主的沙地东南缘的萨拉乌苏河河谷地区.本文选取位于沙地腹地,厚度为3.5 m的风成砂-河湖相沉积序列——神水台(SSTG)剖面为研究对象,基于AMS 14C和OSL年代数据,推测得出剖面中湖相层的上界和下界分别为约24.2 ka B.P .和42.7ka B.P.,依据沉积地层和环境代用指标分析结果,针对末次冰期毛乌素沙地湖泊消涨的一般过程进行了探讨.结果表明,自约5万年以来,由神水台(SSTG)剖面指示了两次明显的湖泊主要发育期,时间分别约为42.7~34.3 ka B.P.和31.1~24.2 ka B.P.,期间粘土含量、有机质、红度均表现为低值,为含淡水螺壳化石的典型湖泊相沉积,且与毛乌素沙地已有湖泊发育的年代结果基本一致.在两期湖相层之间的砂层,平均粒径、砂含量表现为峰值,指示了一次明显的湖泊消退的过程,其时间约为34.3~31.1 ka B.P.;在湖相层上下可能均为风力作用为主导的风沙沉积.通过区域对比并初步探讨其可能的驱动机制,结果表明SSTG剖面记录的湖泊消涨过程主要受控于东亚季风强度的变化.展开更多
基金National Natural Science Foundation of China(41901094)National Natural Science Foundation of China(41930641)Fundamental Research Funds for the Central Universities(GK202103148)。
文摘The Mu Us dune field in China has become a focal region for research of the prevention and control of desertification.Agricultural practices in this area have been modernized in recent years,evidenced by the development of Center Pivot Irrigation(CPI)farmlands.However,the impacts of CPI farmlands on combating desertification remain poorly understood.This study chose the southeastern part of the Mu Us dune field as a study area to investigate the variations of CPI farmlands from 2009 to 2018 and the influencing factors.The results showed growth trends in both the number and the area of these CPI farmland units over the period.The areas of meso-and micro-scale CPI farmland units stabilized over time to mainly 0-0.2 km2 and 0.2-0.4 km2,respectively;Topography,temperature,and geological substratum were preliminarily identified as the major natural factors driving the development of the CPI farmlands.Within the context of varied stakeholders,the potential for soil erosion,and damage to natural vegetation,the current study suggests that strict management of CPI farmland is required through effective long-term planning and land-use policies.The results of this study can assist in realizing the sustainable development of agriculture and its ecological significance in dune field areas.
文摘毛乌素沙地保存着晚第四纪以来的多种沉积序列,记录了过去数十万年以来的古气候变化信息.文章通过地层对比与OSL测年相结合,建立了毛乌素沙地中部乌审旗地区发育厚11.6m的MLL黄土剖面245 ka B.P.以来的年代框架,并对地层划分、沉积特征及其古环境指示意义进行了分析.结果表明：MLL地层剖面是与黄土高原地区相似但又具有特殊性的黄土-古土壤序列,同时也明显不同于沙漠-黄土过渡带常见的古风成砂-古土壤序列.该剖面出露了L3以上连续稳定的黄土-古土壤沉积层以及地表风沙层FS.L1的上下砂黄土层之间夹有一个弱发育古土壤层,S1和S2分别具有两个古土壤复合层,紧接S1、S2a、S2b及L1b底部发育有连续稳定的钙结核淀积层.地表风沙层下部有薄层弱发育砂质土层,未见明显的全新世中期古土壤（S0）发育.L1、S1与S2具有与典型黄土相似的一般特征,可作为MLL剖面地层划分以及年龄控制的标志层.MLL剖面黄土层和古土壤层中的砂质成分含量均较高,＞63 μm砂粒含量分别达到了57.11％和44.77％,但在全剖面未见埋藏古风成砂层存在.MLL剖面CaCO3含量的旋回变化与黄土高原地区一致,黄土层CaCO3含量显著高于古土壤层,发育较好的S1b、S2b中CaCO3含量分别只有0.13％、1.31％.MLL剖面不同层次之间的磁化率对比不明显,黄土磁化率值与古土壤相差极小.245 ka B.P.以来强劲的冬季风作用和风尘堆积,使毛乌素沙地中部一直处于鄂尔多斯高原“风沙高原”的控制之下,即使在暖湿气候条件下的间冰期,粘化层风化淋滤作用也相对较弱.
文摘毛乌素沙地位于东亚季风边缘区,对于气候变化响应敏感.基于沙地的侵蚀-堆积关系,在侵蚀作用为主的沙地西北部和中部很难找到沉积相对连续且分辨率较高的地层剖面,因此已有的末次冰期古气候环境研究多集中于堆积作用为主的沙地东南缘的萨拉乌苏河河谷地区.本文选取位于沙地腹地,厚度为3.5 m的风成砂-河湖相沉积序列——神水台(SSTG)剖面为研究对象,基于AMS 14C和OSL年代数据,推测得出剖面中湖相层的上界和下界分别为约24.2 ka B.P .和42.7ka B.P.,依据沉积地层和环境代用指标分析结果,针对末次冰期毛乌素沙地湖泊消涨的一般过程进行了探讨.结果表明,自约5万年以来,由神水台(SSTG)剖面指示了两次明显的湖泊主要发育期,时间分别约为42.7~34.3 ka B.P.和31.1~24.2 ka B.P.,期间粘土含量、有机质、红度均表现为低值,为含淡水螺壳化石的典型湖泊相沉积,且与毛乌素沙地已有湖泊发育的年代结果基本一致.在两期湖相层之间的砂层,平均粒径、砂含量表现为峰值,指示了一次明显的湖泊消退的过程,其时间约为34.3~31.1 ka B.P.;在湖相层上下可能均为风力作用为主导的风沙沉积.通过区域对比并初步探讨其可能的驱动机制,结果表明SSTG剖面记录的湖泊消涨过程主要受控于东亚季风强度的变化.
