Environmental variability within the Chinese desert-loess transition zone                 over the last 20000 years

Zhou, Wei; Dodson, John; Head, Martin J.; Li, B. S.; Hou, Yuanjun; Xia, Lu; Donahue, D. J.; Jull, A. J. T.

doi:10.1191/0959683602hl525rr

Cited by 76 publications

(40 citation statements)

References 18 publications

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“…There is a general agreement that the deserts exhibited a major northwestward contraction compared to their modern distribution. Nevertheless, there are some differences in detail: for example, for the mid-Holocene, Zhou et al [2002] demonstrated that the southern desert margin shifted about 3°in latitude northward (to 41°N) (green dashed line in Figure 4); Jin et al [2001] suggested that the desert/loess boundary moved about 250 km westward (pink dashed line in Figure 4); Dong et al [1997] consider that the desert/loess boundary belt shifted northwestward to near the modern 200-300 mm annual isohyet (dark purple dotted line in Figure 4), and Lu et al [2013] suggested that the East Sandy Land was almost completely stabilized and exhibited a major retreat while the margin of the West Desert exhibited a smaller change (blue dashed line in Figure 4). …”

Section: 1002/2014gl059952mentioning

confidence: 99%

Distribution and vegetation reconstruction of the deserts of northern China during the mid‐Holocene

Qin

Guo

et al. 2014

Geophysical Research Letters

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Desertification is potentially a serious threat to society, and therefore, it is critical to understand how deserts may respond to future climate change. The mid-Holocene (6 ± 0.5 14 C ka) was warmer than present, and the distribution of deserts at this time may have implications for understanding their response to future warming. Here we reconstruct the distribution of deserts in northern China during the mid-Holocene by combining data on vegetation type and the sedimentary facies of aeolian deposits. The results demonstrate that during the mid-Holocene, the deserts retreated northwestward to the location of the modern 300 mm isohyet. Most of the Eastern Desert was stabilized with steppe or forest-steppe vegetation, whereas the Western Desert exhibited no significant change and remained mobile, occupied by desert vegetation. The deserts in northern China were greatly reduced during the mid-Holocene because of the enhancement of the East Asian summer monsoon in a warmer climate than today.

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Section: 1002/2014gl059952mentioning

confidence: 99%

Distribution and vegetation reconstruction of the deserts of northern China during the mid‐Holocene

Qin

Guo

et al. 2014

Geophysical Research Letters

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“…This shows that climatic oscillations may have a very different expression in eastern Asia than the "cold, dry" North Atlantic younger Dryas event [25]. These effects in China appear to be controlled by changes to the flow of monsoonal precipitation [21,22,27]. There is increasing evidence that these local effects may also occur in many different parts of the world.…”

Section: Correlations Of Climatic Data In Chinese Loess Depositsmentioning

confidence: 99%

Accelerator Mass Spectrometry at Arizona: Geochronology of the Climatic Record and Connections with the Ocean

Jull

Burr

Beck

et al. 2002

The Scientific World JOURNAL

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There are many diverse uses of accelerator mass spectrometry (AMS). 14 C studies at our laboratory include much research related to paleoclimate, with 14 C as a tracer of past changes in environmental conditions as observed in corals, marine sediments, and many terrestrial records. Terrestrial records can also show the influence of oceanic oscillations, whether they are short term, such as ENSO (El Niño/Southern Oscillation), or on the millennial time scale. In tracer applications, we have developed the use of 129 I as well as 14 C as tracers for nuclear pollution studies around radioactive waste dump sites, in collaboration with IAEA. We discuss some applications carried out in Tucson, AZ, for several of these fields and hope to give some idea of the breadth of these studies.KEY WORDS: accelerator mass spectrometry, carbon-14, paleoclimate, radiocarbon dating, beryllium-10, corals, forest fires, ENSO DOMAINS: environmental chemistry, freshwater systems, global systems, isotopes in the environment INTRODUCTIONIn this paper, we describe our new accelerator mass spectrometry (AMS) system and also summarize some aspects of AMS applications at the University of Arizona facility. Over the last 2 decades, AMS has gradually evolved into the standard method of radionuclide measurements, especially for 1580 Jull et al.: Arizona: Geochronology of the Climatic Record TheScientificWorldJOURNAL (2002) 2, 1579-1593 radiocarbon. At the University of Arizona, we now operate two AMS machines. The first machine is a 2. AMS RADIOCARBON MEASUREMENTS PretreatmentIt is important to consider the careful pretreatment of samples for radiocarbon dating, since improper cleaning can affect the results. Although basic procedures are uniform, pretreatment can vary between different radiocarbon laboratories. The processing of an AMS radiocarbon sample at Arizona follows several well-defined steps, which are summarized below for different types of samples:1. Organic materials such as charcoal, wood, cellulose, plant material, and animal tissue: after physical inspection, the samples are cleaned with 1 N HCl acid, 0.1% NaOH, and 1 N HCl (acid-base-acid [ABA] pretreatment), washed with distilled water, dried, and combusted at 900°C with CuO. 2. Carbonates: samples are etched with 100% H 3 PO 4 to remove 50 to 85% of the carbonate, dried, and hydrolyzed with H 3 PO 4 . An alternative is to use selective etching [3]. 3. Marine and lacustrine sediments: after cleansing in 1 N HCl and drying, the sample is combusted at 400°C in ~0.3 atm oxygen gas. We will discuss specific problems of sediment dating later in this paper. 4. Textiles, parchment, canvas, art works, and artifacts: the samples are given the ABA pretreatment and, after washing and drying, they are Soxhlet extracted with hexane, then ethanol, and finally methanol. After washing in distilled water and drying, they are combusted at 900°C with CuO[4]. 5. Ivory: samples are given a light acid pretreatment or a light ABA pretreatment. Dried samples are combusted at 900°C with CuO.Once the gr...

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“…Shi (2005) used an assemblage of tools found in ancient sites to deduce the activities of past subsistence economies, which were then compared with the findings of environmental studies. W. Zhou et al (2002), Song and Zhang (2001), and Ren (2000b) gathered environmental data in the southwest region of Northeast China in an attempt to determine whether human activities had caused deforestation and desertification during prehistoric times. All these studies are indicative of major achievements in the development of environmental archaeology in Northeast China.…”

Section: History and Recent Developmentsmentioning

confidence: 99%

Commentary: A Critical Review of Environmental Archaeology in Northeast China

Jia¹

2011

asi

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Environmental archaeology in northeastern China has reached a critical period of development, although the state of progress varies across this large geographical region. The lack of collaboration between archaeologists and associated scientists remains the main obstacle in current research. Almost exclusively conducted by dedicated scientists, research in the field is often ignored by archaeologists because it is not presented within an archaeological context. Furthermore, the research is not of a high spatial and temporal resolution: there is the tendency to make broad generalizations about large regions over long periods of time and to disregard areas that do not fit their general climatic models. Another problem is the misguided borrowing of concepts developed in other parts of the world, for example, the Holocene Climate Optimum (HCO), which is well defined in prehistoric Europe but is still being developed in China. Many researchers have simply applied this term to the same period in China and assumed that the climate around that period resembled that of prehistoric Europe, despite the fact that this is currently unsupported by local palaeo-environmental evidence. Other obstacles to the development of environmental archaeology include deterministic approaches and oversimplistic research procedures. To address these problems, a conversion of qualitative data to quantitative data on temperature and precipitation is required. Future research should be conducted by teams of scientists and archaeologists working collaboratively on both natural and archaeological deposits, in order to establish a strong foundation for further environmental reconstruction research.

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Environmental variability within the Chinese desert-loess transition zone over the last 20000 years

Cited by 76 publications

References 18 publications

Distribution and vegetation reconstruction of the deserts of northern China during the mid‐Holocene

Distribution and vegetation reconstruction of the deserts of northern China during the mid‐Holocene

Accelerator Mass Spectrometry at Arizona: Geochronology of the Climatic Record and Connections with the Ocean

Commentary: A Critical Review of Environmental Archaeology in Northeast China

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