Human genetic history in East Asia is poorly understood. To clarify population relationships, we obtained genome-wide data from 26 ancient individuals from northern and southern East Asia spanning 9500 to 300 years ago. Genetic differentiation in this region was higher in the past than the present, which reflects a major episode of admixture involving northern East Asian ancestry spreading across southern East Asia after the Neolithic, thereby transforming the genetic ancestry of southern China. Mainland southern East Asian and Taiwan Strait island samples from the Neolithic show clear connections with modern and ancient individuals with Austronesian-related ancestry, which supports an origin in southern China for proto-Austronesians. Connections among Neolithic coastal groups from Siberia and Japan to Vietnam indicate that migration and gene flow played an important role in the prehistory of coastal Asia.Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Ancient DNA (aDNA) techniques applied to human genomics have significantly advanced in the past decade, enabling large-scale aDNA research, sometimes independent of human remains. This commentary reviews the major milestones of aDNA techniques and explores future directions to expand the scope of aDNA research and insights into present-day human health.Copyright © 2022 Elsevier Inc. All rights reserved.

The use of lake sedimentary DNA to track the long-term changes in both terrestrial and aquatic biota is a rapidly advancing field in paleoecological research. Although largely applied nowadays, knowledge gaps remain in this field and there is therefore still research to be conducted to ensure the reliability of the sedimentary DNA signal. Building on the most recent literature and seven original case studies, we synthesize the state-of-the-art analytical procedures for effective sampling, extraction, amplification, quantification and/or generation of DNA inventories from sedimentary ancient DNA (sedaDNA) via high-throughput sequencing technologies. We provide recommendations based on current knowledge and best practises.

The temporal and spatial coarseness of megafaunal fossil records complicates attempts to to disentangle the relative impacts of climate change, ecosystem restructuring, and human activities associated with the Late Quaternary extinctions. Advances in the extraction and identification of ancient DNA that was shed into the environment and preserved for millennia in sediment now provides a way to augment discontinuous palaeontological assemblages. Here, we present a 30,000-year sedimentary ancient DNA (sedaDNA) record derived from loessal permafrost silts in the Klondike region of Yukon, Canada. We observe a substantial turnover in ecosystem composition between 13,500 and 10,000 calendar years ago with the rise of woody shrubs and the disappearance of the mammoth-steppe (steppe-tundra) ecosystem. We also identify a lingering signal of Equus sp. (North American horse) and Mammuthus primigenius (woolly mammoth) at multiple sites persisting thousands of years after their supposed extinction from the fossil record.© 2021. The Author(s).

Denisova Cave in southern Siberia is the type locality of the Denisovans, an archaic hominin group who were related to Neanderthals1–4. The dozen hominin remains recovered from the deposits also include Neanderthals5,6 and the child of a Neanderthal and a Denisovan7, which suggests that Denisova Cave was a contact zone between these archaic hominins. However, uncertainties persist about the order in which these groups appeared at the site, the timing and environmental context of hominin occupation, and the association of particular hominin groups with archaeological assemblages5,8–11. Here we report the analysis of DNA from 728 sediment samples that were collected in a grid-like manner from layers dating to the Pleistocene epoch. We retrieved ancient faunal and hominin mitochondrial (mt)DNA from 685 and 175 samples, respectively. The earliest evidence for hominin mtDNA is of Denisovans, and is associated with early Middle Palaeolithic stone tools that were deposited approximately 250,000 to 170,000 years ago; Neanderthal mtDNA first appears towards the end of this period. We detect a turnover in the mtDNA of Denisovans that coincides with changes in the composition of faunal mtDNA, and evidence that Denisovans and Neanderthals occupied the site repeatedly—possibly until, or after, the onset of the Initial Upper Palaeolithic at least 45,000 years ago, when modern human mtDNA is first recorded in the sediments.

Contents 924 I. 925 II. 925 III. 927 IV. 929 V. 930 VI. 930 VII. 931 VIII. 933 IX. 935 X. 936 XI. 938 938 References 938 SUMMARY: Recent advances in sequencing technologies now permit the analyses of plant DNA from fossil samples (ancient plant DNA, plant aDNA), and thus enable the molecular reconstruction of palaeofloras. Hitherto, ancient frozen soils have proved excellent in preserving DNA molecules, and have thus been the most commonly used source of plant aDNA. However, DNA from soil mainly represents taxa growing a few metres from the sampling point. Lakes have larger catchment areas and recent studies have suggested that plant aDNA from lake sediments is a more powerful tool for palaeofloristic reconstruction. Furthermore, lakes can be found globally in nearly all environments, and are therefore not limited to perennially frozen areas. Here, we review the latest approaches and methods for the study of plant aDNA from lake sediments and discuss the progress made up to the present. We argue that aDNA analyses add new and additional perspectives for the study of ancient plant populations and, in time, will provide higher taxonomic resolution and more precise estimation of abundance. Despite this, key questions and challenges remain for such plant aDNA studies. Finally, we provide guidelines on technical issues, including lake selection, and we suggest directions for future research on plant aDNA studies in lake sediments.© 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Studies along elevational gradients worldwide usually find the highest plant taxa richness in mid-elevation forest belts. Hence, an increase in upper elevation diversity is expected in the course of warming-related treeline rise. Here, we use a time-series approach to infer past taxa richness from sedimentary ancient DNA from the south-eastern Tibetan Plateau over the last ~18,000 years. We find the highest total plant taxa richness during the cool phase after glacier retreat when the area contained extensive and diverse alpine habitats (14-10 ka); followed by a decline when forests expanded during the warm early- to mid-Holocene (10-3.6 ka). Livestock grazing since 3.6 ka promoted plant taxa richness only weakly. Based on these inferred dependencies, our simulation yields a substantive decrease in plant taxa richness in response to warming-related alpine habitat loss over the next centuries. Accordingly, efforts of Tibetan biodiversity conservation should include conclusions from palaeoecological evidence.

During the last glacial–interglacial cycle, Arctic biotas experienced substantial climatic changes, yet the nature, extent and rate of their responses are not fully understood1–8. Here we report a large-scale environmental DNA metagenomic study of ancient plant and mammal communities, analysing 535 permafrost and lake sediment samples from across the Arctic spanning the past 50,000 years. Furthermore, we present 1,541 contemporary plant genome assemblies that were generated as reference sequences. Our study provides several insights into the long-term dynamics of the Arctic biota at the circumpolar and regional scales. Our key findings include: (1) a relatively homogeneous steppe–tundra flora dominated the Arctic during the Last Glacial Maximum, followed by regional divergence of vegetation during the Holocene epoch; (2) certain grazing animals consistently co-occurred in space and time; (3) humans appear to have been a minor factor in driving animal distributions; (4) higher effective precipitation, as well as an increase in the proportion of wetland plants, show negative effects on animal diversity; (5) the persistence of the steppe–tundra vegetation in northern Siberia enabled the late survival of several now-extinct megafauna species, including the woolly mammoth until 3.9 ± 0.2 thousand years ago (ka) and the woolly rhinoceros until 9.8 ± 0.2 ka; and (6) phylogenetic analysis of mammoth environmental DNA reveals a previously unsampled mitochondrial lineage. Our findings highlight the power of ancient environmental metagenomics analyses to advance understanding of population histories and long-term ecological dynamics.

随着分子生物学技术的发展，DNA技术的应用逐渐从生物学研究拓展到进化、环境和气候变化等研究领域。因为DNA容易受到水解、氧化、紫外辐射、酶解等过程的破坏，所以人们认为DNA很容易降解，保存时间不长，但是近年来的研究成果显示，古生物和古人类的化石或骨骼、冻土、湖泊海洋沉积物等样品中包含已保存数千年甚至长达数百万年以来的古DNA。古DNA作为重要的信息载体，可以诠释人类、动植物和微生物进化和迁移过程及它们对环境和气候变化的响应。反过来，古DNA在古环境、古气候重建方面也起着重要作用，沉积物样品的古DNA往往保存了历史时期的水体和水体周围环境以及气候变化等信息。通过对沉积物中古DNA的研究，可以获得历史时期的水生生物(包括藻类、水生动植物等)的群落演化，和水体周围岸基生活的动植物群落(植物落叶、动物毛发冲带到水体并沉积下来)演替，进而反演水体和水体周围气候环境以及气候变化信息。通过研究古人类和动物化石中保存的DNA，可以探讨人类的迁徙和进化过程，溯源家畜的驯化历史。本文将介绍环境古DNA的保存和可靠性评价，重点探讨古DNA在古生态以及古环境、古气候重建研究中的优势及应用，并展望古DNA在生物进化和环境研究等领域的应用前景。

In recent years, the development of new techniques in molecular biology offers a new way for understanding the evolution of lake ecosystem. Ancient DNA could well record the migration and evolution of animals, plants, algae and even microbes, and thus has become an effective tool to reconstruct paleoclimate and paleoenvironment. Studies on the ancient DNA preserved in lake sediments have provided abundant information and high-resolution data that are needed for reconstruction of ancient microbial, plant, or animal community, as well as the ancient environmental conditions. Here, we firstly introduced the preservation characteristics of the ancient DNA and DNA extraction methods from lake sediments, and then reviewed the latest molecular biology techniques for studying ancient DNA preserved in lake sediments. We also discussed the application of ancient DNA in lake sediments including reconstruction of paleoclimate, paleoecology and the impacts of human activities on paleoenvironment. Finally, some problems and possible trends on the research of ancient DNA in lake sediments were summarized.

分子生物学技术的发展，为从分子生物学角度探讨湖泊生态系统演化提供了一个新窗口。依据湖泊沉积物中古DNA研究，从古微生物、动植物群落结构组成及数量变化等方面开展研究，可进一步反演湖泊及周边的气候环境变化，探讨生物与气候、人类活动之间的关系。本文首先介绍了湖泊沉积物中古DNA来源、保存特点以及提取方法，其次比较分析了现代分子生物技术在湖泊沉积物古DNA中的应用特点，并阐述了湖泊沉积物古DNA在重建古气候、古生态以及人类活动对古环境影响方面的应用，最后对目前湖泊沉积物古DNA研究方法存在的一些问题进行了总结。

Study on paleovegetation is with great significance on understanding the modern vegetation composition, distribution, and its responses to global change. During recent decades, it has been a rapidly developing field in molecular palaeoecology to track the long-term vegetation composition and plant diversity changes by using sedimentary ancient DNA. Meanwhile, the lacustrine sedimentary ancient plant DNA (PsedaDNA) is becoming a popular proxy for palaeovegetation and palaeoecological studies. However, the modern process of PsedaDNA remains unclear compared with pollen analysis, which limits its further application. Here, we reviewed the PsedaDNA researches and tried to elucidate the modern processes of PsedaDNA, including the source, deposition, and preservation processes, and to understand the relationships between the PsedaDNA and modern vegetation. PsedaDNA is mainly derived from the lake surroundings or within the catchment. The abundance and composition of PsedaDNA are influenced by the biomass of terrestrial plants, and factors such as DNA degradation, the adsorption, and dilution of particles in soils and sediments during the transportation and deposition. Moreover, the preservation of PsedaDNA is largely affected by both biotic and abiotic factors, including the microbial activity, chemical properties of lake water (conductivity and pH), and sediment composition. PsedaDNA can be used to reveal the contemporary vegetation and climate information but was incompetent to quantitatively palaeovegetation reconstruction. Considering the complexity of modern processes, the interpretation of PsedaDNA results should be done with extra caution. To sum up, PsedaDNA is still in its infancy, which has been benefiting from the progress of molecular biotechnology, optimization of experimental design, species barcodes, and sophistication of reference databases. The PsedaDNA technique including DNA metabarcoding and metagenomics will certainly promote the development of Chinese palaeophytoecology research.

对植被历史变化过程的研究是理解现代植被组成、分布及其对全球变化响应的基础。近年来, 随着分子古生态学的发展, 分析沉积介质中的陆生植物古DNA信号, 以研究植被及植物多样性演变的历史过程正在成为研究热点, 湖泊沉积植物古DNA已成为古植被和古生态学研究的成熟代用指标。然而与第四纪孢粉分析相比较, 湖泊沉积植物古DNA的现代过程依然不明确, 成为其进一步发展和应用的限制因素。基于此, 该文综述了湖泊沉积植物古DNA技术研究进展, 尝试阐明湖泊沉积植物古DNA的现代过程, 包括植物DNA的来源、沉积和保存过程及其影响因素, 以及植物DNA与现代植被的关系等。已有研究表明, 湖泊沉积植物古DNA主要来自湖泊周边或流域范围, 其丰度和组成除受到源植物生物量的影响外, 同样受到沉积物的搬运和沉积过程中DNA降解作用、土壤以及沉积物中颗粒的吸附过程和稀释作用等因素的影响。湖泊沉积物中植物DNA的保存则主要受到微生物活动、湖水的化学性质(电导率和pH值)、湖泊深度、沉积物组成等一系列生物与非生物因素的共同影响。湖泊沉积植物古DNA可以揭示其沉积时代的植物群落类型以及气候环境信息, 但目前并不能够用来定量重建古植被变化过程。鉴于湖泊沉积植物古DNA现代过程的复杂性, 对研究结果的解释要格外小心。与孢粉分析相比, 湖泊沉积植物古DNA研究仍处于起步阶段, 但随着分子生物技术的进步、实验设计的优化、物种条形码的扩充及参考数据库的完善等, 以DNA宏条形码和宏基因组学为主要技术手段的植物古DNA技术, 必将推动我国植物古生态研究的进一步发展。

To reconstruct past vegetation from pollen or, more recently, lake sedimentary DNA (sedDNA) data is a common goal in palaeoecology. To overcome the bias of a researcher’s subjective assessment and to assign past assemblages to modern vegetation types quantitatively, the modern analogue technique (MAT) is often used for vegetation reconstruction. However, a rigorous comparison of MAT-derived pollen-based and sedDNA-based vegetation reconstruction is lacking. Here, we assess the dissimilarity between modern taxa assemblages from lake surface-sediments and fossil taxa assemblages from four lake sediment cores from the south-eastern Tibetan Plateau and northern Siberia using receiver operating characteristic (ROC) curves, ordination methods, and Procrustes analyses. Modern sedDNA samples from 190 lakes and pollen samples from 136 lakes were collected from a variety of vegetation types. Our results show that more modern analogues are found with sedDNA than pollen when applying similarly derived thresholds. In particular, there are few modern pollen analogues for open vegetation such as alpine or arctic tundra, limiting the ability of treeline shifts to be clearly reconstructed. In contrast, the shifts in the main vegetation communities are well captured by sedimentary ancient DNA (sedaDNA). For example, pronounced shifts from late-glacial alpine meadow/steppe to early–mid-Holocene coniferous forests to late Holocene Tibetan shrubland vegetation types are reconstructed for Lake Naleng on the south-eastern Tibetan Plateau. Procrustes and PROTEST analyses reveal that intertaxa relationships inferred from modern sedaDNA datasets align with past relationships generally, while intertaxa relationships derived from modern pollen spectra are mostly significantly different from fossil pollen relationships. Overall, we conclude that a quantitative sedaDNA-based vegetation reconstruction using MAT is more reliable than a pollen-based reconstruction, probably because of the more straightforward taphonomy that can relate sedDNA assemblages to the vegetation surrounding the lake.

Little is currently known about preservation of plant DNA in lake sediments. Most prior information originates from laboratory experiments while systematic field‐based studies are still lacking. Here, we used the “g” and “h” universal primers for the P6 loop region of the chloroplast trnL (UAA) intron to amplify plant DNA from 219 lake surface sediments from China and Siberia. We introduce (i) the percentage of sequence counts with the best identity ≥95%, (ii) weighted average identity, (iii) weighted average DNA fragment length, and iv) rarefied richness of terrestrial seed plants of plant DNA metabarcoding as proxies for sedimentary DNA preservation and relate them to five environmental variables (lake water conductivity, lake water pH, mean July air temperature, and sampling depth, lake size) using boosted regression tree (BRT) analyses. Our results suggest that lake water chemical characteristics, that is, electrical conductivity and pH, are the most important variables for the preservation of plant DNA in lake sediments. Intermediate water conductivities (100–500 μS cm−1) and neutral to slightly alkaline water pH (7–9) may facilitate plant DNA preservation. Furthermore, deep lakes seem to support plant DNA preservation as indicated by relatively high rarefied richness. We also find high rarefied richness in small lakes compared with large lakes, but this result needs to be assessed by more studies in the future. None of our BRT models shows that mean July air temperature is a key variable to limit plant DNA preservation. To conclude, our results suggest that sedimentary DNA studies can preferentially select deep lakes characterized by intermediate water conductivities and neutral to slightly alkaline pH conditions.

Over the last decade, an increasing number of studies have used lake sediment DNA to trace past landscape changes, agricultural activities or human presence. However, the processes responsible for lake sediment formation and sediment properties might affect DNA records via taphonomic and analytical processes. It is crucial to understand these processes to ensure reliable interpretations for "palaeo" studies. Here, we combined plant and mammal DNA metabarcoding analyses with sedimentological and geochemical analyses from three lake-catchment systems that are characterised by different erosion dynamics. The new insights derived from this approach elucidate and assess issues relating to DNA sources and transfer processes. The sources of eroded materials strongly affect the "catchment-DNA" concentration in the sediments. For instance, erosion of upper organic and organo-mineral soil horizons provides a higher amount of plant DNA in lake sediments than deep horizons, bare soils or glacial flours. Moreover, high erosion rates, along with a well-developed hydrographic network, are proposed as factors positively affecting the representation of the catchment flora. The development of open and agricultural landscapes, which favour the erosion, could thus bias the reconstructed landscape trajectory but help the record of these human activities. Regarding domestic animals, pastoral practices and animal behaviour might affect their DNA record because they control the type of source of DNA ("point" vs. "diffuse").

499 I. 499 II. 500 III. 500 IV. 500 V. 500 VI. 501 VII. 502 VIII. 504 504 References 505 SUMMARY: Ancient DNA (aDNA) from lake sediments, peats, permafrost soils, preserved megafaunal gut contents and coprolites has been used to reconstruct late-Quaternary floras. aDNA is either used alone for floristic reconstruction or compared with pollen and/or macrofossil results. In comparative studies, aDNA may complement pollen and macrofossil analyses by increasing the number of taxa found. We discuss the relative contributions of each fossil group to taxon richness and the number of unique taxa found, and situations in which aDNA has refined pollen identifications. Pressing problems in aDNA studies are contamination and ignorance about taphonomy (transportation, incorporation, and preservation in sediments). Progress requires that these problems are reduced to allow aDNA to reach its full potential contribution to reconstructions of Quaternary floras. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

The aim of the study was a statistical evaluation of the impact of selected\n soil factors ? water potential (pF), total organic carbon content (TOC) and\n land use ? on the total DNA content and dehydrogenase activity (DHA) in\n Mollic Gleysol. Additionally, we wanted to establish the interrelations\n between two of the most important biological parameters in soli: activity of\n intracellular dehydrogenases and total DNA content. Soil originating from the\n surface layer of the control site displayed higher DHA (c.a. by 57%) and DNA\n content (c.a. by 25%) as compared to an cultiavted meadow. Our results also\n indicate a significant (p <0.05) positive relationship between the soil DNA\n content and DHA. Importantly, intensive and systematical agricultural soil\n usage resulted in the reduction of its DHA and DNA content.

DNA metabarcoding refers to the DNA-based identification of multiple species from a single complex and degraded environmental sample. We developed new sampling and extraction protocols suitable for DNA metabarcoding analyses targeting soil extracellular DNA. The proposed sampling protocol has been designed to reduce, as much as possible, the influence of local heterogeneity by processing a large amount of soil resulting from the mixing of many different cores. The DNA extraction is based on the use of saturated phosphate buffer. The sampling and extraction protocols were validated first by analysing plant DNA from a set of 12 plots corresponding to four plant communities in alpine meadows, and, second, by conducting pilot experiments on fungi and earthworms. The results of the validation experiments clearly demonstrated that sound biological information can be retrieved when following these sampling and extraction procedures. Such a protocol can be implemented at any time of the year without any preliminary knowledge of specific types of organisms during the sampling. It offers the opportunity to analyse all groups of organisms using a single sampling/extraction procedure and opens the possibility to fully standardize biodiversity surveys.© 2012 Blackwell Publishing Ltd.

In order to reveal the formation process， material source and sedimentological significance of the climbing dunes in the Shannan wide valley section of Yarlung Tsangpo River， cross-sectional sampling was conducted on the climbing dunes of Langsailing， and the particle size and geochemical elemental characteristics of the climbing dunes sediments in different topography parts were analyzed. The results show that the grain size composition of the surface sediments of the climibing dunes is mainly fine and medium sands， while the river floodplain and terraces show obvious wind-water interaction， and the windward and leeward slopes show obvious aeolian characteristics； The particle size characteristics are different in different terrain. The particle size gradually becomes finer and better sorted from the riverbed to upwind slope， while the opposite trend is observed from upwind slope to the leeward slope. The geochemical element composition of the sediments is dominated by Si， Al， Fe and Na， and the small difference in the climbing dune section indicates that they have similar depositional environment. Compared with the upper continental crust （UCC）， all the elements are deficient except Si. The A-CN-K ternary diagram and CIA index reveal that chemical weathering of the surface sediments is in the early stage， while the A-CNK-FM diagram indicates that the spatial distributions of Fe and Mg elements are spatially different， which is the result of sorting action of wind. From the chemical weathering index perspective， the weathering of the sediment is enhanced from the river bed to the windward slope. In summary， material source and wind dynamics are important factors leading to the spatial differences in grain size and chemical elements. Therefore， we determine the climbing dunes of Langsailing are near-source dunes， and the material source is mainly from the river sediments of the Yarlung Tsangpo River. Meanwhile， the variance of sediment characteristics at different topography part are the active response to the interaction of wind and water.

为揭示雅鲁藏布江山南宽谷段爬坡沙丘的形成过程、物源及沉积学意义，对山南宽谷段朗赛岭爬坡沙丘进行断面采样，分析爬坡沙丘不同地貌部位沉积物的粒度和地球化学元素特征。结果表明：爬坡沙丘表层沉积物以细沙和中沙为主，河漫滩和阶地表现出明显的风水交互特点，迎风坡和背风坡则表现为明显的风成特点；不同地貌部位沉积物粒度特征不同，从河漫滩到迎风坡坡顶，沉积物粒度整体变细，分选逐渐变好，从迎风坡顶到背风坡，分选变差。沉积物的地球化学元素以Si、Al、Fe、Na为主，在不同地貌部位分布差异较小，表明其具有相似的沉积环境，和上陆壳（UCC）相比，除Si以外其余常量元素均有亏损。微量元素集中分布于河漫滩沉积物中，部分存在于稳定矿物中的微量元素可分布于坡麓地带。A-CN-K图解及CIA值揭示了朗赛岭爬坡沙丘处于化学风化的初期，A-CNK-FM图则表明Fe、Mg元素在空间上存在差异，是差异风力风选的结果。从化学风化指标来看，从河漫滩到迎风坡，沉积物的风化程度增强。综上所述，物源和风动力是导致爬坡沙丘粒度和化学元素存在空间差异的重要因素，朗赛岭爬坡沙丘属于近源沙丘，沙源主要是雅鲁藏布江河流相沉积物，不同地貌部位沉积物特征的差异性是对风、水交互作用的积极响应。

Late Quaternary loess-paleosol deposits on the northeastern Qinghai-Tibet Plateau （NE QTP） recorded information of environmental changes in this area. Previous studies have been carried out on their source area. However， due to the insufficient space coverage of samples in previous studies， this issue still needs further study. We collected samples of loess-paleosol， eolian sands， fluvial sediments and lacustrine deposits on the NE QTP. Chemical compositions of these samples （less than 75 μm fraction） were determined by X-ray fluorescence （XRF） spectrometry. The results show that： （1） The chemical composition of the late Quaternary loess-paleosol on the NE QTP is mainly composed of SiO2， Al2O3， Fe2O3， and CaO； compared with the composition of UCC （upper continental crust）， the late Quaternary loess-paleosol on the NE QTP has higher CaO and MgO content， lower Na2O and K2O content. （2） K2O/Al2O3 （molar ratio）， TiO2/Al2O3 （molar ratio）， Zr/Nb and Zr/Ti ratios show that the source area of the late Quaternary loess-paleosol in the Qinghai Lake area on the NE QTP is different from that of the fluvial sediments and lacustrine sediments in this area， indicating that the loess-paleosol in the Qinghai Lake area is probably from a region far away from the Qinghai Lake area. （3） K2O/Al2O3 （molar ratio）， TiO2/Al2O3 （molar ratio）， Zr/Nb and Zr/Ti ratios show that the late Quaternary loess-paleosol on the NE QTP and the eolian sand， fluvial sediments and lacustrine deposits in the Qaidam Basin cannot be distinguished， indicating that the weathered detrital material in the Qaidam Basin is likely to provide substantial material for loess-paleosol on the NE QTP under the influence of the near-surface northwest wind and the Westerly circulation.

青藏高原东北部的晚第四纪黄土-古土壤记录了该区环境变化的信息，以往的物源研究样品空间覆盖度不足，仍需进一步研究。在青藏高原东北部较大范围地采集了黄土-古土壤、风成砂、河流沉积、湖相沉积样品，并对这些样品小于75 μm组分的元素组成进行了X射线荧光光谱（XRF）分析。结果表明：（1）青藏高原东北部晚第四纪黄土-古土壤的元素组成以SiO₂、Al₂O₃、Fe₂O₃、CaO为主；与UCC（上地壳）相比，青藏高原东北部晚第四纪黄土-古土壤的CaO、MgO含量较高，Na₂O、K₂O含量较低。（2）具有物源指示意义的K₂O/Al₂O₃（摩尔比）、TiO₂/Al₂O₃（摩尔比）、Zr/Nb和Zr/Ti比值图解显示青藏高原东北部青海湖地区的晚第四纪黄土-古土壤与当地的河流沉积、湖相沉积存在较大差异，揭示它们来自青海湖地区以外的区域。（3）K₂O/Al₂O₃（摩尔比）、TiO₂/Al₂O₃（摩尔比）、Zr/Nb和Zr/Ti比值图解显示青藏高原东北部的晚第四纪黄土-古土壤与柴达木盆地的风成砂、河流沉积和湖相沉积重叠在一起，表明柴达木盆地的风化细碎屑物质在近地面西北风、高空西风环流的作用下很可能为青藏高原东北部黄土-古土壤的堆积提供了主要物源。

eDNA refers to DNA extracted from an environmental sample with the goal of identifying the occurrence of past or current biological communities in aquatic and terrestrial environments. However, there is currently a lack of knowledge regarding the soil memory effect and its potential impact on lake sediment eDNA records. To investigate this issue, two contrasted sites located in cultivated environments in France were studied. In the first site, soil samples were collected (n = 30) in plots for which the crop rotation history was documented since 1975. In the second site, samples were collected (n = 40) to compare the abundance of currently observed taxa versus detected taxa in cropland and other land uses. The results showed that the last cultivated crop was detected in 100% of the samples as the most abundant. In addition, weeds were the most abundant taxa identified in both sites. Overall, these results illustrate the potential of eDNA analyses for identifying the recent (< 10 years) land cover history of soils and outline the detection of different taxa in cultivated plots. The capacity of detection of plant species grown on soils delivering sediments to lacustrine systems is promising to improve our understanding of sediment transfer processes over short timescales.