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Zhengxi Tan Larry L. Tieszen Shuguang Liu Emmanuel Tachie-Obeng 《Climatic change》2010,100(3-4):703-715
Many savannas in West Africa have been converted to croplands and are among the world’s regions most vulnerable to climate change due to deteriorating soil quality. We focused on the savanna-derived cropland in northern Ghana to simulate its sensitivity to projected climate change and nitrogen fertilization scenarios. Here we show that progressive warming–drying stress over the twenty-first century will enhance soil carbon emissions from all kinds of lands of which the natural ecosystems will be more vulnerable to variation in climate variables, particularly in annual precipitation. The carbon emissions from all croplands, however, could be mitigated by applying nitrogen fertilizer at 30–60 kg N ha???1 year???1. The uncertainties of soil organic carbon budgets and crop yields depend mainly on the nitrogen fertilization rate during the first 40 years and then are dominated by climate drying stress. The replenishment of soil nutrients, especially of nitrogen through fertilization, could be one of the priority options for policy makers and farm managers as they evaluate mitigation and adaptation strategies of cropping systems and management practices to sustain agriculture and ensure food security under a changing climate. 相似文献
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高质量矿床的勘查战略 总被引：2，自引：0，他引：2
邮我国矿产勘查应以高质量矿床作为目标矿床的战略;认为勘查高质量矿床需要加强矿床模式的研究和ＧＩＳ技术的推广应用;确保高质量矿床战略成功实施的思路包括：（１）以高质量金矿床作为勘查目标;（２）加强对典型高质量矿床的研究,寻找同类型高质量矿床;（３）从构造环境发展演化的机理进行成矿分析,制定高质量矿床勘查战略;（４）打破地域限制,促进勘查队伍之间的竞争机制。 相似文献
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浅析我国潜在优势非金属矿产资源的开发利用与保护——以内蒙古乌兰察布市石墨、萤石、电气石矿为例 总被引：1，自引：0，他引：1
内蒙古自治区乌兰察布市,以石墨、电气石、萤石等为代表的非金属矿产资源相当丰富,且矿石品级好、质量高,潜在开发利用价值极高。但是国内长期以来在非金属矿物的开发利用与经营管理方面相对粗放,产品低端,技术水平和加工能力低,开采消耗量大,造成资源浪费严重,经济转化效益不高,优势无法较好的释放。特别是对非金属矿的潜在优势估计不足,节约利用与有效保护方面重视不够,一直存在"低出高进、外国以购代采"的现象。笔者试图通过乌兰察布市较具代表性的几类非金属矿产的国内外开发利用现状、当地的潜在资源优势等分析,提出合理开发利用与保护潜在优势非金属矿产资源的对策:一是树立正确的资源观,清醒地认识到非金属矿的潜在优势,有必要作为国家重要战略资源进行限制性开采和必要的储备与保护;二是针对非金属矿山的资源整合,应以产业链的延伸和新兴矿物利用技术为准入门槛和发展方向,促进矿山的技术改造与产业升级;三是发挥政府的职能,借鉴我国近年在稀土资源管理方面的模式,进行顶层设计和政策扶持,有必要成立潜在优势非金属矿物开发利用的专门技术研究机构,进行有针对性的产品深加工技术研发与推广。 相似文献
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MABI Awei ZHANG Mingchun YANG Zhengxi LI Yanlong WEN Dengkui LIU Xuyang 《《地质学报》英文版》2017,91(2):741-742
<正>Objective The Emeishan large igneous province(ELIP)in SW China is the only one large igneous province in China recognized by international geologists.Previous studies of ELIP over past two decades indicate that the ELIP age,duration,scale and generation mechanism are still controversial.Among those scientific topics,some 相似文献
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MABI Awei YANG Zhengxi ZHANG Mingchun WEN Dengkui LI Yanlong LIU Xuyang 《《地质学报》英文版》2018,92(1):89-105
In the western Yangtze Block, widespread Mesoproterozoic to Neoproterozoic rocks are the key to understanding the Precambrian tectonic-magmatic evolution of the region. However, their petrogenesis and tectonic setting are still controversial. In this paper, zircon U-Pb ages, Sm-Nd isotopic and whole-rock geochemical data are reported from selected fresh samples in the southern Dechang county, southwestern China, in order to constrain their emplacement age and magma source, as well as their petrogenesis and tectonic setting. They are mainly composed of biotite monzogranite, monzonitic granite, biotite granodiorites, and quartz diorite. Two ages of 1055 ± 43 Ma and 837.6 ± 3.8 Ma were obtained through zircon U-Pb dating by LA-ICP-MS and LA-MC-ICP-MS, respectively. According to their major element compositions, the Grenville-age granites are peraluminous calc-alkaline series calcic S-type granite. In contrast, the mid-Neoproterozoic granites are metaluminous calc-alkaline series alkalic I-type granite. Furthermore, the S-type granites are enriched in LREEs relative to HREEs with(La/Yb)_N ratios of 3.85–18.56 and underwent major fractionation with strongly negative Eu anomalies(Eu/Eu~* = 0.38–0.66). In the MORB-normalized trace element variation diagram, all the samples are enriched in Ce and large ion lithophile elements such as Rb, Th, and K, and depleted in high field strength elements such as Nb, and Ti, with negative Sr and Ti anomalies. The I-type granites are enriched in LREEs with slight negative Eu anomalies(Eu/Eu~* = 0.83–0.93). They are characterized by the enrichment of highly incompatible elements(such as K, Rb, Ba, Th) and LREEs, relative to MORB. Neodymium isotopic data show that the S-type granites display ~(143)Nd/(~(144) Nd) values of 0.51241–0.51256, and have ε_(Nd)(t = 1055 Ma) values of(-3.29) to(-3.81). Calculated t_(DM) ages yield values from 1.87 to 1.91 Ga with the t_(DM).2 stg ages of 1.86 to 1.9 Ga. The I-type granites have ~(143)Nd/(~(144) Nd) ratios between 0.51192 and 0.51195, corresponding to initial ε_(Nd)(t = 837 Ma) values of 1.22 to 5.63. Calculated t_(DM) ages yield values from 1.0 to 1.38 Ga and the t_(DM).2 stg ages yield values from 0.99 to 1.06 Ga. The S-type granites are distinguished as syn-collision granite, whereas the I-type granites were formed as arc magmas according to the Rb-(Yb+Ta) and R_1-R_2 tectonic discrimination diagrams. To conclude, there are two types of spatially associated granite, the Mesoproterozoic S-type granite which were derived from remelting of upper crustal mudstone and/or clastics and resulted from the convergence of two continental plates, and the mid-Neoproterozoic I-type granite which formed in continental arc and resulted from mantle-derived magma mixed crust material, in the western Yangtze Block. Furthermore, we suggest that collision between the Yangtze and Cathaysia blocks occurred at about 1055 Ma, and caused the Stype granite. The I-type granite related to the subduction of oceanic lithosphere eastward underneath the Yangtze Block in the mid-Neoproterozoic. 相似文献
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山西煤类齐全,煤质较优良,是我国主要的炼焦煤和无烟煤基地。以山西多年来的煤炭资源预测资料和众多矿区勘查资料为基础,全面总结了山西省太原组和山西组煤类分布特征及其变质作用。研究认为,山西的煤类分布具有明显的南北分带性,38°线以北煤变质程度较低,煤类较单一,以气煤为主;38°线以南煤变质程度相对较高,煤类较多;山西省煤变质类型主要有深成变质、岩浆热变质和接触变质三种类型,深成变质是基础,也是山西省最重要的变质类型,岩浆热变质主要是燕山期岩浆活动叠加于深成变质的基础上造成的,接触变质只是局部的,对区域性的变质影响甚微。研究成果可以为山西省煤炭资源的合理利用提供依据。 相似文献
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通过对王坡矿井的构造特征、水文地质条件、煤层发育特征、煤储层特征以及地形等条件进行分析,探讨了不同煤层气开发方式的适应性,并结合王坡煤矿开采煤层情况、瓦斯现状,确定3号煤层为煤层气开发的目标煤层.从王坡矿井地形条件,控制面积、集输复杂性及经济效益分析,认为该区不适合采用地面垂直井方式开发煤层气;从构造特征及钻井工艺等方面分析,不宜采用对接井、羽状水平井和水平井煤层气开发方式;丛式井开发方式对地形要求较低、占地面积较小、钻井工艺成熟,经济效益好,可作为王坡矿井进行煤层气开发的首选井型. 相似文献
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基于长沙市中心城区1979年、1989年、2003年、2011年、2014年5个年份的土地利用现状图,借助ArcGIS、SPSS分析工具,提取居住、工业、服务三大功能用地,从方向、圈层、强度、用地间转变及轴带趋向对长沙城市功能用地扩展的时空特征及驱动力进行研究。结果表明：① 用地扩展模式以“圈层式、轴带式”为主,并逐渐向“多组团式”过渡,由单一的向外扩展向内部功能间演替和外部扩展相结合转变。整体扩展方向经历了由“东、南、东南-西北、东、东南、北”的变化,但各类用地的扩展方向有所差异;② 从扩展强度看,居住用地远远高于城市总体扩展强度,造成了城市功能空间失衡的现象,服务配套明显滞后,部分分区在扩展过程中,出现了与规划定位严重不符的矛盾;③ 功能用地间的转变主要集中在城市核心区,表现出以核心-外围明显分异的差距。外围片区的功能较为单一,融合度不够,未来应增强配套服务功能。④ 从经济驱动力、政策调控力、生态制约力与吸引力、社会助推力四个方面分析了功能用地扩展时空差异的驱动因素。⑤ 从“问题导向-现象归纳-本质剖析-策略应对”提出了城市功能用地扩展研究的基本研究框架。 相似文献