Li Y.,Jilin University |
Li Q.,Jilin University |
Guo D.,Jilin University |
Guo D.,Chinese Academy of Land and Resource Economics |
And 2 more authors.
Ecological Engineering | Year: 2016
The natural Leymus chinensis grassland in western Jilin Province of NE China has been extensively degraded, thereby restricting the development of animal husbandry. Using theory of ecological stoichiometry homeostasis, this study investigated the homeostasis of L. chinensis at different degradation stages in the research area using a homeostasis model. Results showed that the degraded grassland generally had lower soil carbon (C), nitrogen (N) and phosphorus (P) compared with normal L. chinensis grassland. In particular, the degraded grassland exhibited severe shortage of P, but L. chinensis showed strong homeostasis. Except for C in the roots and leaves and P in stems, the N, P and corresponding ratios had higher homeostasis than 1, between 1.53 and 15.92. The homeostasis of N in L. chinensis was higher than that of P, and the homeostasis of C/P was higher than that of C/N and N/P. L. chinensis absorbs and uses nutritive elements in a conservative manner, which enables it to remain productive during changes in the external environment. Therefore, grassland degradation control should prioritize the protection of dominant species. Appropriate use of N and P fertilizers is suggested for the recovery of the seriously degraded L. chinensis grassland ecosystem. © 2016 Elsevier B.V..
Liao S.,Wuhan University |
Chen S.,Wuhan University |
Deng X.,Wuhan University |
Li P.,Chinese Academy of Land and Resource Economics
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2014
The rare earth element (REE) features of Xi'ao copper-tin polymetallic deposit were analyzed to discuss the forming source and environment. The results show that REE distribution patterns of altered granites are similar to unaltered granite, suggesting that the ore forming fluid probably derived from magma. Compared with unaltered granite, the content of total REE of potassic alteration granite increases, and the HREE rises higher than LREE. Besides, La and Ce of the LREE increase more than Pr and Nd. Secondary potassium feldspar inherits the REE characteristics of the alteration fluid. These probably result from high temperature and F, Cl, CO2 rich features of the fluid. The content of total REE of epidotization-chloritization granite is relatively unchanged. The decease of LREE and slight increase of HREE perhaps are caused by the combination of factors of alteration, absorption of mica and early potassium alteration. Eu and Ce anomaly indicate that potassic alteration occurs at relatively high temperature in oxidation conditions, and epidotization- chloritization occurs at relatively low temperature in reducing conditions. REE are closely related to main ore-forming elements in the altered granites, providing relevant information for ore prediction in inner granite acteration zone.
Lin C.-M.,Nanjing University |
Li Y.-L.,Nanjing University |
Zhuo H.-C.,Nanjing University |
Zhuo H.-C.,Chinese Academy of Land and Resource Economics |
And 4 more authors.
Marine and Petroleum Geology | Year: 2010
Late Quaternary shallow biogenic gas reservoirs have been discovered and exploited in the Qiantang River (QR) estuary area, eastern China. The fall of global sea level during the Last Glacial Maximum resulted in the formation of the QR incised valley. From bottom to top, the incised valley successions can be grouped into four sedimentary facies: river channel facies, floodplain-estuarine facies, estuarine-shallow marine facies, and estuarine sand bar facies.All commercial biogenic gas pools occur in floodplain-estuarine sand bodies of the QR incised valley and its branches. The deeply incised valleys provided favorable conditions for the generation and accumulation of shallow biogenic gas.The clay beds that serve as the direct cap beds of the gas pools are mostly restricted within the QR incised valley, with burial depths ranging from 30 to 80 m, remnant thicknesses of 10-30 m, and porosities of 42.2-62.6%. In contrast, the mud beds cover the whole incised valley and occur as indirect cap beds, with burial depths varying from 5 to 35 m, thicknesses of 10-20 m, and porosities of 50.6-53.9%. The pore-water pressures of clay and mud beds are higher than that of sand bodies, and the difference can be as much as 0.48 MPa. The pore-water pressures of clay or mud beds can exceed the total pore-water pressure and gas pressure of underlying sand reservoirs. Shallow biogenic gas can be completely sealed by the clay and mud beds, which have higher pore-water pressure. The direct cap beds have better sealing ability than the indirect cap beds.Generally, the pore-water pressure dissipation time of clay and mud beds is conspicuously longer than that of sand beds. This indicates that the clay and mud beds have worse permeability and better sealing ability than the sand beds. However, once the gas enters the sand lenses, the pore-water pressure cannot release efficiently. © 2009 Elsevier Ltd.
Chen W.,Chinese Academy of Geological Sciences |
Xu Z.,Nanjing University |
Chen M.,Chinese Academy of Geological Sciences |
Yu Y.,Chinese Academy of Land and Resource Economics
Mineralogy and Petrology | Year: 2016
This paper investigates the petrogenesis of the Xinxian granitic batholith and its tectonic implications for the Dabie orogen. Two Xinxian granites yield Early Cretaceous 238U/206Pb ages of 122.7 ± 1.3 Ma and 123.6 ± 2.2 Ma. The granites are metaluminous differentiated I–type granites, with A/NKC ranging from 0.90 to 0.96. The chondrite–normalised REE patterns display significant LREE/HREE enrichments with moderate negative Eu anomalies (Eu/Euδ = 0.30 ~ 0.85). The granites show enrichments in large–ion lithophile elements (LILEs, e.g. Rb, K, Th and U) and depletions in Sr, Ba and high field strength elements (HFSEs, e.g. Nb, Ta and Ti). Inherited zircons of different age (Neoproterozoic, one Early Proterozoic, one Archean and two Triassic inherited metamorphic zircons) are identified. The Early Cretaceous magmatic zircons contain enriched Hf isotopes with εHf (t) values ranging from −26.9 to −18.7 (average = −22.5), more enriched than their probable alleged source, i.e. the Dabie Complex, represented by the Neoproterozoic and Triassic inherited zircons. Thus, the Archean and Early Proterozoic crustal materials may represent an enriched end member source for the parental magma of the Xinxian granites. Provenance analysis of the magmatic zircons in the North China and Yangtze blocks demonstrates that the Early Proterozoic inherited zircon in Xinxian has North China affinity. Thus, we proposed a multiple–sourced petrogenetic model for the Xinxian granitic batholith, which suggests that the batholith was formed by the remelting of a mixed crustal assemblage, including the Archean and Early Proterozoic crust of the North China Block, the Neoproterozoic crust of the Yangtze Block, as well as some Triassic collision–related ultra–high pressure (UHP) metamorphic rocks. © 2015, Springer-Verlag Wien.
Zhang C.Y.,Chinese Academy of Land and Resource Economics
Applied Mechanics and Materials | Year: 2014
Taking Liguanpu riverside well field in Shenyang as the object, groundwater sustainable exploitation is calculated by groundwater flow numerical simulation method. Optimizing and adjusting the groundwater pumping wells will be more convenient and intuitive by established simulation model so that we can exploit groundwater resource reasonably, it is a good way to improve the production of water source. Groundwater sustainable exploitation is 10.03×104m3/d. The optimized pumping well has contributed to infiltration recharge from captured surface water resources and adjacent groundwater lateral recharge. It benefits groundwater to be exploited and used in reason. © (2014) Trans Tech Publications, Switzerland.