Differential Effects of Natural Grazing and Feedlot Feeding on Yak Fecal Microbiota

Variation in food and diet shapes the diversity of the gut microbiota of ruminants. The present study investigated the microbial diversity in the fecal microbiota of yaks reared under natural grazing and feedlot system. A total of 48 domestic yaks with an average age of 7.5 years were selected from two different grazing habitats: one group grazed on natural pasture (grazing yaks—GY) while the other group was fed fodder and concentrate (feedlot yaks—FY). Crude protein, non-fiber carbohydrate, hemicelluloses, and digestible dry matter contents of natural pastures were higher than those in the feedlot. The lower insoluble fiber contents were found in grazing land. The 16S rRNA gene sequencing revealed 675 and 348 unique operational taxonomic units (OTUs) in the GY and FY, respectively, in addition to 1,778 common OTUs. Overall, a total of 9,891 OTUs were identified as a whole, of which 6,160 OTUs were from GY and 3,731 were from FY. Shannon index analysis revealed a higher bacterial diversity in GY than FY. At the phylum level, Firmicutes were dominant bacterial taxa in both groups. The relative abundance of Firmicutes in GY (56% ± 0.05) was higher than in FY (41% ± 0.08). At the family level, GY had a significantly higher abundance of Ruminococcaceae (p < 0.001) and Rikenellaceae (p < 0.001) than FY, but FY had a significantly higher abundance of Prevotellaceae than GY (p < 0.001). At the genus level, abundances of Faecalibacterium, Alloprevotella, and Succinivibrio were higher in FY than in GY. This study presents novel information on fecal bacterial composition and diversity in yaks reared under two different production systems

Six million years of magnetic grain-size records reveal that temperature and precipitation were decoupled on the Chinese Loess Plateau during ~4.5-2.6Ma

Magnetic grain-size variations have been used as sensitive paleoclimate proxies to investigate the evolution of the East Asian summer monsoon, but their relationship with temperature and precipitation is not entirely clear. Here we find that two magnetic grain-size proxy records (χARM/χLF and χARM/SIRM, where χARM, χLF and SIRM are anhysteretic remanent magnetization susceptibility, magnetic susceptibility measured at 470Hz and saturation isothermal remanent magnetization, respectively) of Chinese loess and red-clay sediments co-vary during the last 6Ma, except between ~4.5 and 2.6Ma, when these two records had opposite trends. We attribute this disparate behavior to the different responses of χARM/χLF and χARM/SIRM to temperature and precipitation during ~4.5-2.6Ma, when temperature and precipitation on the Chinese Loess Plateau were decoupled. A comparison of the loess and red-clay χARM/χLF and χARM/SIRM records with the global ice-volume proxy records reveals that χARM/χLF is more sensitive to temperature variations than χARM/SIRM. The results suggest that temperature on the Chinese Loess Plateau had a cooling trend from ~4.5 to ~2.6Ma, whereas rainfall tended to increase. Our studies demonstrate that joint analysis of loess χARM/χLF and χARM/SIRM records can reveal paleoclimatic information that cannot be revealed by a single parameter. © 2013 University of Washington

Two 8-Hydroxyquinolinate Based Supramolecular Coordination Compounds: Synthesis, Structures and Spectral Properties

Two new Cr(III) complexes based on 2-substituted 8-hydroxyquinoline ligands, namely [Cr(L1)3] (1), (HL1=(E)-2-[2-(4-nitro-phenyl)-vinyl]-8-hydroxy-quinoline) and [Cr(L2)3] (2), (HL2=(E)-2-[2-(4-chloro-phenyl)vinyl]-8-hydroxy-quinoline), were prepared by a facile hydrothermal method and characterized thoroughly by single crystal X-ray diffraction, powder X-ray diffraction, FTIR, TGA, ESI-MS, UV-Visible absorption spectra and fluorescence emission spectra. Single crystal X-ray diffraction analyses showed that the two compounds featured 3D supramolecular architectures constructed from noncovalent interactions, such as π···π stacking, C-H···π, C-H···O, C-Cl···π, C-H···Cl interactions. The thermogravimetric analysis and ESI-MS study of compounds 1 and 2 suggested that the Cr(III) complexes possessed good stability both in solid and solution. In addition, the ultraviolet and fluorescence response of the HL1 and HL2 shown marked changes upon their complexation with Cr(III) ion, which indicated that the two 8-hydroxyquinolinate based ligand are promising heavy metal chelating agent for Cr3+

Magnetic parameter variations in the Chaona loess/paleosol sequences in the central Chinese Loess Plateau, and their significance for the middle Pleistocene climate transition

A high-resolution rock magnetic investigation was performed on the Chaona Quaternary loess/paleosol sequences in the Central Chinese Loess Plateau. Based on a newly developed independent unturned time scale and magnetic records, we reconstructed the history of the East Asia monsoons during the last 3. Ma and explored the middle Pleistocene climate transition (MPT). Rock magnetic results show that the loess layers are characterized by relatively high coercivity and remanent coercivity, lower magnetic susceptibility (MS), and that the paleosol layers are characterized by relatively high MS, saturation magnetization and remanent saturation magnetization. Spectrum analyses indicate that there are various periods in addition to orbital periodicities. According to the onset and stable appearance of 100 kyr period, we consider that the MPT recorded in this section began at ~. 1.26. Ma and was completed by ~. 0.53. Ma, which differs from previous investigations based on orbitally tuned time scales. The forcing mechanism for the MPT was more complicated than just the orbital forcing. We conclude that the rapid uplift of the Tibetan Plateau may have played an important role in the shift of periodicities during the middle Pleistocene. © 2013 University of Washington

Formation and re-orientation of the Suerkuli Basin within the Altyn Tagh in northeastern Tibetan Plateau since late Miocene

The Altyn Tagh Fault (ATF) had formed in Eocene time, however, the temporal evolution of slip along the fault remains elusive, despite its important role in governing growth of the Tibetan Plateau (TP) and evaluating models of continental lithosphere deformation. Here we perform a high-resolution magnetostratigraphic study on Neogene sediments from the Suerkuli Basin, a small basin located between two active strands of the ATF. Results show that both depositional environment and the sedimentation rate changed at about 5.4 and 6 Ma, respectively. Lithofacies shift from conglomerates and sandstones with parallel and cross beddings to mudstones with horizontal bedding, suggesting a sedimentary fluvial to lacustrine depositional environment shift. Even aridification increased over northern China, from the Tarim Basin to the Qaidam Basin, during late Miocene to early Pliocene times, lacustrine deposition had started in the Suerkuli Basin still. We argue that an increase in slip rate along the ATF triggered concurrently forming of the intermontane basin. The inferred timing of increased slip-rate on the ATF coincides with a variation in movement of the Indian Plate relative to Eurasian Plate since Late Miocene-Early Pliocene time. Our work suggests that a re-orientation of crustal shortening and deformation in the northern TP began since late Miocene and supports the idea that the modern boundary of the TP orogen had rejuvenated to adjust deformation in plate boundary conditions

Rock magnetic record of late Neogene red clay sediments from the Chinese Loess Plateau and its implications for East Asian monsoon evolution

The Quaternary loess-paleosol and underlying Neogene red clay sequences on the Chinese Loess Plateau (CLP) contain a remarkable continental record of past East Asian monsoon changes and aridification of the Asian interior. While monsoon variability during the Quaternary is reasonably well understood, the evolution and dynamics of the monsoon during the Neogene are still debated. The rock magnetism of aeolian sediments is a well-established tool for reconstructing the palaeoclimatic history of Asia. Here, we present a rock magnetic record from Late Neogene red clay sediments of the Chaona section in the central CLP. The results indicate that the main magnetic minerals in the red clay are magnetite, maghemite, hematite and goethite, similar to the overlying Quaternary loess-palaeosol sequences. The high-resolution rock magnetic record, combined with the results of other proxies, demonstrate a stepwise intensification of the summer monsoon and a progressive enhancement of the winter monsoon in East Asia during the Late Neogene. Based on the results, the climatic evolution of East Asia can be divided into three intervals: Interval III, from 8.1 to 6.8 Ma, is characterized by a cool, dry climate with a relatively weak East Asian Summer Monsoon (EASM) and East Asian Winter Monsoon (EAWM); Interval II, from 6.8 to 4.3 Ma, is characterized by cool/warm cycles; and Interval I, from 4.3 to 2.8/2.6 Ma, was warm and humid, and within which the EASM strengthened rapidly and the EAWM fluctuated considerably, with an increasing trend. We infer that before 4.3 Ma the variations of both the EASM and EAWM were closely related to global cooling and that the intensified EASM during the late Pliocene was primarily caused by tectonic events, including the gradual closure of the Panama Seaway and the uplift of the Tibetan Plateau, rather than by global cooling

Size-differentiated REE characteristics and environmental significance of aeolian sediments in the Ili Basin of Xinjiang, NW China

Aeolian loess in the Ili Basin is an important geological archive for studying the changes in paleoclimate and sources of dust particles. Size-differentiated rare earth elements (REE) may help to distinguish potential dust sources. This study investigates the size-differentiated REE characteristics from three sites including the Zhaosu loess and the Kekdala desert sediments from the Ili Basin, and the Chaona loess from the Chinese Loess Plateau (CLP). Our results show that the patterns of variation of the REE characteristics in different size fractions can act as improved source tracers for aeolian sediments. Moreover, the REE characteristics of the < 2 mu m particles are sensitive indicators for distinguishing dust particles transported over long distances in the semi-arid areas with limited pedogenesis such as the Ili Basin. However, it should be interpreted cautiously in the CLP due to the post-depositional chemical weathering. The REE characteristics of coarse fractions are effective tracers for tracking changes in proximal dust sources and regional boundary level circulations. Our study has implications for identifying the exact source(s) of the Ili loess, which is helpful to understand paleoclimate changes and westerly circulation patterns in Central Asia

Six million years of magnetic grain-size records reveal that temperature and precipitation were decoupled on the Chinese Loess Plateau during similar to 4.5-2.6 Ma

Magnetic grain-size variations have been used as sensitive paleoclimate proxies to investigate the evolution of the East Asian summer monsoon, but their relationship with temperature and precipitation is not entirely clear. Here we find that two magnetic grain-size proxy records (chi(ARM)/chi(LF) and chi(ARM)/SIRM, where chi(ARM), chi(LF) and SIRM are anhysteretic remanent magnetization susceptibility, magnetic susceptibility measured at 470 Hz and saturation isothermal remanent magnetization, respectively) of Chinese loess and red-clay sediments co-vary during the last 6 Ma, except between similar to 4.5 and 2.6 Ma, when these two records had opposite trends. We attribute this disparate behavior to the different responses of chi(ARM)/chi(AF) and chi(ARM)/SIRM to temperature and precipitation during similar to 4.5-2.6 Ma, when temperature and precipitation on the Chinese Loess Plateau were decoupled. A comparison of the loess and red-clay chi(ARM)/chi(LF) and chi(ARM)/SIRM records with the global ice-volume proxy records reveals that chi(ARM)/chi(LF) is more sensitive to temperature variations than chi(ARM)/SIRM. The results suggest that temperature on the Chinese Loess Plateau had a cooling trend from similar to 4.5 to similar to 2.6 Ma, whereas rainfall tended to increase. Our studies demonstrate that joint analysis of loess chi(ARM)/chi(LF) and chi(ARM)/SIRM records can reveal paleoclimatic information that cannot be revealed by a single parameter.</p