Scaling of soil carbon,nitrogen, phosphorus and C:N:P ratio patterns in peatlands of China     

Zhongsheng Zhang  Zhenshan Xue  Xianguo Lyu  Shouzheng Tong  Ming Jiang 《中国地理科学(英文版)》2017,27(4):507-515

Inspired by the importance of Redfield-type C:N:P ratios in global soils,we looked for analogous patterns in peatlands and aimed at deciphering the potential affecting factors.By analyzing a suite of peatlands soil data(n = 1031),mean soil organic carbon(SOC),total nitrogen(TN) and total phosphorous(TP) contents were 50.51%,1.45% and 0.13%,respectively,while average C:N,C:P and N:P ratios were 26.72,1186.00 and 46.58,respectively.C:N ratios showed smaller variations across different vegetation coverage and had less spatial heterogeneity than C:P and N:P ratios.No consistent C:N:P ratio,though with a general value of 1245:47:1,was found for entire peatland soils in China.The Northeast China,Tibet,Zoigê Plateau and parts of Xinjiang had high soil SOC,TN,TP,and C:P ratio.Qinghai,parts of the lower reaches of the Yangtze River,and the coast zones have low TP and N:P ratio.Significant differences for SOC,TN,TP,C:N,C:P and N:P ratios were observed across groups categorized by predominant vegetation.Moisture,temperature and precipitation all closely related to SOC,TN,TP and their pairwise ratios.The hydrothermal coefficient(RH),defined as annual average precipitation divided by temperature,positively and significantly related to C:N,C:P and N:P ratios,implying that ongoing climate change may prejudice peatlands as carbon sinks during the past 50 years in China.  相似文献   

南川黄泥垭隧道工程对水文地质条件的影响分析   总被引：2，自引：2，他引：0  

曹锐  吕玉香  裴建国 《中国岩溶》2017,36(5):691-696

隧道工程建设无疑对岩溶地区的水文地质环境地质带来巨大冲击。文章以重庆市南川区黄泥垭隧道工程为实例,采用地面调查、示踪试验、长观监测等方法进行综合研究,剖析隧道工程对隧址区水文地质环境的影响。研究结果表明:黄泥垭隧道工程改变了隧址区的地下水流场,疏干地表地下水、加剧干旱缺水程度,并随之出现新的人工水点——隧道涌水;同时隧道工程影响了水资源空间分配格局、降低了水资源利用率。   相似文献   

Distribution,Compositions and Significance of Oceanic Red Beds     

Xuan Lyu  Zhifei Liu 《地球科学进展》2017,32(12):1307-1318

Oceanic red beds are widely distributed in the global oceans and across the entire Phanerozoic period, which mostly appeared after oceanic anoxic events. They represent typical oxygen-rich sedimentary environment and play a significant role on ocean science research. Numerous studies have been carried out since the oceanic red beds were discovered. However, previous studies mainly focused on the Cretaceous oceanic red beds, and the understanding of the characteristics and scientific significance of oceanic red beds are not comprehensive. Therefore, we here summarized the global distribution characteristics and compared mineral and element compositions of various lithological oceanic red beds, including marly, clayey and cherty oceanic red beds. The main mineral and element components of oceanic red beds have no direct relationship with the color of the sediments, and mainly are affected by the regional environment and provenances. Therefore, the mineralogical and geochemical characteristics of oceanic red beds should be analyzed in combination with the regional background. The red coloration of oceanic red beds is controlled mainly by hematite, goethite and manganese-bearing calcite, which have two main mechanisms: ① Colored minerals formed in oxic conditions; ② Colored minerals formed due to low deposition rates. These two mechanisms are not completely independent, but complement one another with either dominance in most oceanic red beds. Lithological characteristics of oceanic red beds are controlled by three factors, including water depth, productivity and nutrients. Therefore, the formation of oceanic red beds should be considered with global changes and regional events. The unique origin mechanism and global distribution characteristics of long time-scale oceanic red beds can be used to indicate sedimentary paleoenvironment, paleo-oceanic current, and paleoclimate change. In addition, hydrothermal or magmatic activities on the ocean floor could also produce red-color deposits that are strongly different from sedimentary oceanic red beds. Based on the existing research, we also put forward the future in-depth studies on the oceanic red beds from multidisciplinary perspectives.  相似文献   

广西恭城奥陶纪含笔石地层   总被引：1，自引：0，他引：1  

唐兰  韩乃仁  张元动 《地层学杂志》2004,28(2):158-167,191

桂北恭城奥陶纪含笔石地层过去因缺乏生物化石证据将其划归于寒武系清溪组。1997年在其中发现笔石后重新将时代确定为奥陶纪,整套地层可划分为8个笔石带.自上而下为:8.Nemagraptus gracilis带;7.Ptero-graptus elegans带;6.Nicholsonograptus fasciculatus带;5.Acrograptus ellesae带;4.Undulograptus austroden-tatus带;3.Exigraptus clavus带;2.Isograptus caduceus cf.imitatus带;1.Didymograptus(Expansograptus)abnormis带。该地层与我国广东、浙江、江西、安徽等地区,以及澳大利亚、北美、英国等的相应层位可以对比。  相似文献   

贝壳珍珠层的X射线衍射研究   总被引：3，自引：1，他引：3  

张刚生  谢先德  戚绍祺  胡萍春 《矿物岩石》2002,22(4):8-11

珍珠层中文石晶体的择优取向是珍珠层具有优异力学性能的重要原因之一，通过对三角帆蚌贝壳珠层的X射线衍射研究，表明珍珠层除存在公认的（002）面网平行珍珠层面的强烈定向文石晶体外，还有强烈的（012）面网平行珍珠层面的亲新定向文石晶体，且在同一贝壳的不同位置，该两种取向的择优取向度变化较大，充分说明了珍珠层结构的不均匀性。  相似文献   

地图模糊矩阵模型与制图术语表述数学化研究     

钟业勋  胡毓钜 《武汉大学学报(信息科学版)》1993,(4)

笔者在过去所研究地图模糊矩阵模型的基础上,进一步探讨了建立地图模糊矩阵模型问题,通过矩阵运算来对地图学中有关制图综合、图象变换等概念给出了数学定义,从而使概念表述数学化。  相似文献   

Trace element composition of magnetite from the Xinqiao Fe–S(–Cu–Au) deposit,Tongling, Eastern China: constraints on fluid evolution and ore genesis     

Yichang Wang  Jianfeng Gao  Xiaowen Huang  Liang Qi  Chuan Lyu 《中国地球化学学报》2018,37(5):639-654

The Xinqiao deposit is one of several polymetallic deposits in the Tongling ore district. There are two types of mineralization in the Xinqiao: skarn-type and stratiform-type. The skarn-type mineralization is characterized by iron oxides such as magnetite and hematite, whereas stratiform-type mineralization is characterized by massive sulfides with small amounts of magnetite and hematite. We defined three types of ores within the stratiform-type mineralization by the mineral assemblages and ore structures. Type I ore is represented by magnetite crosscut by minor calcite veins. Type II is a network ore composed of magnetite and crosscutting pyrite. Type III is a massive ore containing calcite and hematite. Type I magnetite is characterized by highly variable trace element content, whereas Type II magnetite has consistently higher Si, Ti, V, and Nb. Type III magnetite contains more In, Sn, and As than the other two types. Fluid–rock interaction, oxygen fugacity (fO₂), and temperature (T) are the main factors controlling element variation between the different magnetite types. Type I magnetite was formed by more extensive fluid–rock interaction than the other two types at moderate fO₂ and T conditions. Type II magnetite is thought to have formed in relatively low fO₂ and high-T environments, and Type III in relatively high fO₂ and moderate-T environments. Ca?+?Al?+?Mn and Ti?+?V discrimination diagrams show that magnetite in the Xinqiao deposit is hydrothermal in origin and is possibly linked with skarn.  相似文献   

Geological and hydrogeological environment in Tianjin with potential geohazards and groundwater control during excavation     

Yong-Xia Wu  Hai-Min Lyu  Jack Shuilong Shen  Arul Arulrajah 《Environmental Earth Sciences》2018,77(10):392

This paper discusses the geological and hydrogeological features of Quaternary deposits in Tianjin as well as the geohazards related to groundwater hydrology in this region. The soft soil deposits, comprising silt, sand, silty clay and clay, are composed of four aquifer groups. In the first aquifer group, one phreatic aquifer and two confined aquifers have relationships with underground construction in the urban area. These three aquifers are separated by two aquitards and collectively form a multi-aquifer system. During geotechnical construction, potential geohazards present are related to the groundwater, which include water-in-rushing, quicksand and piping hazards. To prevent the aforementioned geohazards, dewatering is conducted; however, groundwater pumping may result in large settlements of the surrounding ground. To reduce pumping-induced settlement, the dewatering–waterproofing system has been adopted. According to the characteristics of the subsoil, excavation depth and the surrounding environment, the dewatering system can be divided into five patterns. In the first four patterns, when pumping is conducted in the excavation pit, the groundwater head in the adjacent aquifers outside the pit decreases due to the leakage effect of the aquitards located between the aquifers. In the fifth pattern, waterproof curtain has cut off the aquifers completely and dewatering in the pit cannot result in settlement around excavation pit. To avoid geohazards related to groundwater hydrology, countermeasures recommended include construction of an effective waterproof curtain, selection of a reasonable excavation dewatering pattern and withdrawal of required groundwater.  相似文献   

Calculation of groundwater head distribution with a close barrier during excavation dewatering in confined aquifer     

Hai-Min Lyu  Shui-Long Shen  Yong-Xia Wu  An-Nan Zhou 《地学前缘(英文版)》2021,12(2):791-803

When pumping is conducted in confined aquifer inside excavation pit(waterproof curtain),the direction of the groundwater seepage outside the excavation changes from horizontal to vertical owing to the existence of the curtain barrier.There is no analytical calculation method for the groundwater head distribution induced by dewatering inside excavation.This paper first analyses the mechanism of the blocking effects from a close barrier in confined aquifer.Then,a simple equation based on analytical solution is proposed to calculate groundwater heads inside and outside of the excavation pit with waterproof curtain(hereafter refer to close barrier)in a confined aquifer.The distribution of groundwater head is derived according to two conditions:(i)pumping with a constant water head,and(ii)pumping with a constant flow rate.The proposed calculation equation is verified by both numerical simulation and experimental results.The comparisons demonstrate that the proposed model can be applied in engineering practice of excavation.  相似文献   

Clay mineral assemblages of the oceanic red beds in the northern South China Sea and their responses to the Middle Miocene Climate Transition     

He  Lei  Liu  Zhifei  Lyu  Xuan  Ma  Pengfei 《中国科学:地球科学(英文版)》2022,65(5):899-909

Science China Earth Sciences - The Middle Miocene Climate Transition (MMCT, ～14 Ma) is the largest cooling event in the Cenozoic “Coolhouse”, which significantly impacts the...  相似文献