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Age and chemical composition of Archean metapelites in the Zhongxiang Complex and implications for early crustal evolution of the Yangtze Craton

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LITHOS 2018年 320卷 280-301页

作者： Wang, Kai Dong, shuwen Li, Zheng-xiang Han, Baofu Chinese Acad Geol Sci Beijing 100037 Peoples R China Peking Univ Sch Earth & Space Sci Minist Educ Key Lab Orogen Belts & Crustal Evolut Beijing 100871 Peoples R China Curtin Univ Sch Earth & Planetary Sci Inst Geosci Res TIGeR Earth Dynam Res Grp Perth WA 6845 Australia Curtin Univ Sch Earth & Planetary Sci ARC Ctr Excellence Core Crust Fluid Syst CCFS Perth WA 6845 Australia Nanjing Univ Sch Earth Sci & Engn Nanjing 210093 Jiangsu Peoples R China Chinese Acad Geol Sci SinoProbe Ctr Beijing 100037 Peoples R China

Chemical composition of sedimentary rocks bears important clues on source rock characteristics and sedimentary processes, providing a critical record of the evolving continental crust Whole-rock major and trace elements, and detrital zircon U-Pb-Hf isotopic data for metapelites of the Archean Yangpo "Group" in the newly discovered Zhongxiang Complex, South China, are employed to investigate the age, provenance, and sedimentary processes of the protoliths, so as to further characterize the early crustal evolution of the Yangtze Craton. Detrital zircon cores from the metapelites yielded a youngest age of around 2.70 Ga with metamorphic rims dated at 1.95 Ga, which in combination with previous geochronological studies on granitic bodies intruding the Yangpo "Group" constrain the depositional age between 2.70 and 2.67 Ga. This makes the protolith of the Yangpo "Group" the oldest sedimentary unit in the Yangtze Craton. Geochemical signatures of the metapelites indicate relatively weak chemical weathering of the source area and weak to moderate post-depositional silicification and K-metasomatism. Diagnostic trace element ratios and REE patterns suggest that the protoliths of the Yangpo metapelites are compositionally immature with a mixed source of (ultra)-mafic (>60%) and felsic rocks, which possibly accumulated in a basin near an active continental margin. Detrital zircons in the Yangpo metapelites are dominated by 2.92-2.85 Ga and 2.80-2.73 Ga age populations with two prominent peaks at 2.87 Ga and 2.78 Ga, which are in agreement with the zircon ages and Hf isotopic compositions of the known older magmatic rocks in the Zhongxiang Complex, indicating that the proximal basement rocks were the principal detrital source. Integrated zircon age and Hf-isotope data suggest that the Archean continental crust of the Zhongxiang Complex was built through three major episodes of crustal growth at 3.55-3.45 Ga, 3.40-3.0 Ga, and 2.92-2.85 Ga, followed by two major episodes of crusta

关键词： Chemical composition Metapelites Yangpo "Group" Zhongxiang Complex Yangtze Craton Archean continental crust

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江南钨矿带高家塝钨多金属矿床矿化分带特征及其指示意义

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矿床地质 2021年第2期40卷 369-383页

作者：任康达张达玉叶龙翔孟翔易洪黄家龙万书文周涛发合肥工业大学资源与环境工程学院安徽合肥230009 华东冶金地质勘查局812地质队安徽铜陵244008 华东冶金地质勘查研究院安徽合肥230088

高家塝钨多金属矿床位于江南钨矿带北部。钨矿化发育在花岗闪长斑岩与黄柏岭组接触的矽卡岩及其两侧。从岩体向外将矿石划分为:花岗闪长斑岩中细脉浸染状白钨矿矿石(类型Ⅰ)、矽卡岩中浸染状白钨矿矿石(类型Ⅱ)、角岩中脉状白钨矿矿石(... 详细信息

高家塝钨多金属矿床位于江南钨矿带北部。钨矿化发育在花岗闪长斑岩与黄柏岭组接触的矽卡岩及其两侧。从岩体向外将矿石划分为:花岗闪长斑岩中细脉浸染状白钨矿矿石(类型Ⅰ)、矽卡岩中浸染状白钨矿矿石(类型Ⅱ)、角岩中脉状白钨矿矿石(类型Ⅲ)3类。高家塝矿床不同类型矿石的白钨矿和磁黄铁矿电子探针(EPMA)分析结果显示,白钨矿w(Mo)从类型Ⅱ(w(Mo)=1.34%~1.40%)→类型Ⅲ(w(Mo)=0.01%~0.17%)→类型Ⅰ(w(Mo)<0.01%)降低。从类型Ⅰ→类型Ⅱ→类型Ⅲ,磁黄铁矿中Cu、Fe元素含量降低;Zn、Co、Ni含量增高。高家塝钨矿床形成白钨矿的成矿流体从类型Ⅱ→类型Ⅲ→类型Ⅰ,氧逸度降低;形成磁黄铁矿的早期石英-硫化物阶段,类型Ⅱ的成矿流体降温速率缓慢,类型Ⅰ和Ⅲ的成矿流体发生快速冷凝作用。区域对比研究显示,高家塝矿床为贫钼白钨矿矿床,形成于还原环境。

关键词：地球化学白钨矿磁黄铁矿 EPMA 成矿指示江南钨矿带

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华北克拉通中东部新太古代晚期变质火山岩及动力学体制

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岩石学报 2021年第1期37卷 113-128页

作者：刘树文包涵高磊孙国正王伟郭荣荣郭博然付敬浩胡雅璐白翔胡方泱北京大学造山带与地壳演化教育部重点实验室地球与空间科学学院北京100871 中国地质大学(北京)地质过程与矿产资源国家重点实验室地球科学与资源学院北京100083 东北大学深部金属矿山安全开采教育部重点实验室资源与土木工程学院地质系沈阳110819 北京矿产地质研究院北京100012 西南石油大学地球科学与技术学院成都610500 中国地震局地质研究所吉林长白山火山国家野外科学观测研究站北京100029 中国地震局地震与火山灾害重点实验室北京100029 中国科学院地质与地球物理研究所岩石圈演化国家重点实验室北京100029

热状态和壳幔岩浆作用是理解早期地壳形成演化动力学机制的关键。华北克拉通是世界范围内为数不多的保存有大量新太古代晚期(约26~25亿年)变质火山岩记录的克拉通之一,对揭示全球新太古代晚期壳-幔动力学演化过程具有重要的指示意义。... 详细信息

热状态和壳幔岩浆作用是理解早期地壳形成演化动力学机制的关键。华北克拉通是世界范围内为数不多的保存有大量新太古代晚期(约26~25亿年)变质火山岩记录的克拉通之一,对揭示全球新太古代晚期壳-幔动力学演化过程具有重要的指示意义。在我们研究组近期关于华北克拉通中东部中新太古代热状态和地壳厚度研究基础上,本文收集并整理了726个华北克拉通中东部(包括中部带)新太古代晚期变质火山岩样品的有效地球化学资料。按照现代通用岩石地球化学标准来分类,这些样品主要包括超铁镁质岩石(其中含苦橄岩、苦橄质玄武岩和科马提岩,~7%)、稀土未分异型玄武岩(~14%)、稀土分异型玄武岩(~27%)、玻安岩(~4%)、高镁安山岩(~12%)、低镁安山岩(~26%)和英安岩-流纹岩(~10%)。然而不同区块之间火山岩岩石组合及其量比存在较大差异,其中吉林南部和赞皇等地区以大量稀土分异型玄武岩、高镁和低镁安山岩为主,含有少量的长英质火山岩;胶东、登封和阜新等地区以稀土未分异和稀土分异型玄武岩占有绝对优势,存在少量安山岩和长英质火山岩;冀北、冀东北部、冀东南部(迁安-滦县)、五台-云中山、辽北、辽南和鲁西等地区岩石组合比较复杂,最突出的特点是出现不同比例的玻安岩,组合有稀土未分异和大量稀土分异型玄武岩、高镁和低镁安山岩,出现少量超铁镁质岩石和长英质火山岩。岩石成因研究揭示稀土未分异型和分异型玄武岩、高镁安山岩和玻安岩主要形成于俯冲板片流体、熔体和沉积物熔体交代地幔的部分熔融,而低镁安山岩、英安岩和其它长英质火山岩则大都经历了上述俯冲相关初始岩浆的结晶分异或地壳物质熔融和地壳混染等过程。新太古代晚期胶东地区表现为相对较薄的地壳厚度和较高的地热梯度(18℃/km),而冀东地区表现为厚的地壳厚度和低的地热梯度(最低8.7℃/km),满足现代俯冲地热梯度需求,其它区域的地温梯度介于热俯冲和现代冷俯冲之间。综合以上资料,我们认为新太古代晚期板块构造体制已经是最主要的壳-幔动力学体制,地幔柱构造体制和板块构造-地幔柱联合作用体制可能仍然在局部地区存在,但其作用范围和强度已经明显减小。因此,随着地幔温度的下降,中太古代到新太古代晚期地幔柱和板片俯冲的转化可能是相互关联、此消彼长的动力学过程,而不是一个突变过程。

关键词：新太古代晚期变质火山岩及其成因地壳热状态动力学体制华北克拉通中东部

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LAmbre封堵器封堵左心耳后密封盘周围漏与封堵器相关血栓发生的关系

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介入放射学杂志 2022年第5期31卷 442-445页

作者：王赛华赵志宏宋湘郝舒雯罗俊武英彪朱茜方明田蓓顾薇宁忠平上海健康医学院附属周浦医院心内科 201318

目的探讨心房颤动(房颤)患者左心耳植入LAmbre封堵器后密封盘周围漏与封堵器相关血栓(DRT)发生的关系。方法回顾性分析2018年5月至2021年6月在上海周浦医院接受LAmbre封堵器封堵左心耳治疗并完成经食管超声心动图复查的137例房颤患者,... 详细信息

目的探讨心房颤动(房颤)患者左心耳植入LAmbre封堵器后密封盘周围漏与封堵器相关血栓(DRT)发生的关系。方法回顾性分析2018年5月至2021年6月在上海周浦医院接受LAmbre封堵器封堵左心耳治疗并完成经食管超声心动图复查的137例房颤患者,比较不同型号LAmbre封堵器植入后密封盘周围漏和DRT发生情况。结果137例患者年龄为(74.9±9.2)岁,>80岁(80~93岁)患者占40.1%,女性占38.7%,房颤血栓栓塞风险(CHA_(2)DS_(2)-VASc)评分、抗凝治疗出血风险评估(HAS-BLED)评分分别为(5.6±1.9)分、(2.7±1.6)分。左心耳植入LAmbre封堵器后1~3 mm密封盘周围漏最常见,仅1例植入3640型LAmbre患者密封盘周围漏为6 mm。比较植入不同型号封堵器后密封盘周围漏发生率,差异无统计学意义(P>0.05)。封堵盘周围漏与DRT发生无相关性。结论心房颤动左心耳植入LAmbre封堵器后1~3 mm密封盘周围漏发生最常见,不同型号LAmbre封堵器间密封盘周围漏与DRT发生负相关。

关键词：心房颤动 LAmbre 左心耳密封盘周围漏封堵器相关血栓

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山羊骨髓间充质干细胞与纤维蛋白胶修复椎间盘纤维环缺损的组织学比较

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中国组织工程研究 2022年第13期26卷 1974-1978页

作者：徐翔吴一民李树文马丽波王宇鹏于英楠孙涛张远任伟银和平内蒙古医科大学第二附属医院微创脊柱外科内蒙古自治区呼和浩特市010030 内蒙古医科大学第二附属医院护理部内蒙古自治区呼和浩特市010030 内蒙古医科大学第二附属医院急诊科内蒙古自治区呼和浩特市010030 内蒙古国际蒙医院手术麻醉科内蒙古自治区呼和浩特市010030 内蒙古医科大学研究生院内蒙古自治区呼和浩特市010059

背景:目前,腰椎间盘摘除术后纤维环破口仍继续存在,容易形成复发型腰椎间盘突出,如何修复纤维环破口是组织工程学的热点问题。目的:比较以明胶海绵为载体的山羊骨髓间充质干细胞移植与纤维蛋白粘合剂修复椎间盘纤维环缺损的能力。方法:... 详细信息

背景:目前,腰椎间盘摘除术后纤维环破口仍继续存在,容易形成复发型腰椎间盘突出,如何修复纤维环破口是组织工程学的热点问题。目的:比较以明胶海绵为载体的山羊骨髓间充质干细胞移植与纤维蛋白粘合剂修复椎间盘纤维环缺损的能力。方法:从山羊髂骨中提取和分离出骨髓间充质干细胞,并将其进行传代培养。将15只山羊随机分为对照组、粘合组、移植组,每组5只(30个椎间盘)。采用手术器械制备0.75 cm×0.75 cm椎间盘纤维环缺损,粘合组利用纤维蛋白粘合剂对破损的纤维环进行粘合,移植组将负载骨髓间充质干细胞悬液(细胞浓度为5×10^(9) L^(-1),体积为10μL)的明胶海绵(0.75 cm×0.75 cm)放入纤维环缺损中,然后逐层进行缝合。术后6,12周,取出纤维环组织进行苏木精-伊红染色、Masson三色明胶染色、AB-PAS染色和Ⅱ型胶原染色。结果与结论:苏木精-伊红染色观察到移植组中软骨细胞、胶原细胞与骨细胞的数量相比其他两组增多,细胞成熟,修复能力更强;Masson三色明胶染色观察到移植组有更多的成纤维细胞和纤维组织;AB-PAS染色观察到移植组有更多的软骨细胞参与修复;Ⅱ型胶原免疫组化染色发现移植组Ⅱ胶原含量最高;上述结果证实了山羊骨髓间充质干细胞对纤维环缺损有更好的修复能力。

关键词：骨髓间充质干细胞纤维蛋白胶组织学观察纤维环 Ⅱ型胶原 Masson染色 AB-PAS染色苏木精-伊红染色

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对比盘式封堵器LAmbre与LAcbes封堵左心耳治疗心房颤动

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中国介入影像与治疗学 2022年第7期19卷 385-390页

作者：赵志宏王赛华朱珞宁郝舒雯罗俊武英彪朱茜方明田蓓顾薇宁忠平宋湘上海健康医学院附属周浦医院心内科上海201318

目的对比以盘式封堵器LAmbre与LAcbes行左心耳封堵(LAAC)治疗心房颤动(AF)的有效性和安全性。方法分析99例接受以LAcbes封堵器(LAcbes组)、130例以LAmbre封堵器(LAmbre组)行LAAC的AF患者,对比治疗效果、安全性及预后。结果LAcbes组左心... 详细信息

目的对比以盘式封堵器LAmbre与LAcbes行左心耳封堵(LAAC)治疗心房颤动(AF)的有效性和安全性。方法分析99例接受以LAcbes封堵器(LAcbes组)、130例以LAmbre封堵器(LAmbre组)行LAAC的AF患者,对比治疗效果、安全性及预后。结果LAcbes组左心耳完全封堵率66.67%(66/99),LAmbre组57.69%(75/130),组间差异无统计学意义(P>0.05)。LAcbes组密封盘直径、固定盘直径及封堵术后周边漏(特别是1~3 mm周边漏)发生率均低于LAmbre组(P均<0.01)。2组围术期均无急性心脏压塞及死亡病例。术后(中位复查时间为术后72天)复查经食管超声心动图,组间器械相关血栓发生率差异无统计学意义(P>0.05)。术后平均随访(12±6)个月,随访期间LAcbes组5例(5/99,5.05%)、LAmbre组1例(1/130,0.77%)发生延迟性心脏压塞,LAcbes组发生脑梗死、短暂性缺血发作各1例,LAmbre组发生脑梗死2例、脑出血1例、死于心力衰竭1例,2组差异均无统计学意义(P均>0.05)。结论盘式封堵器LAmbre与LAcbes封堵左心耳治疗AF的效果及安全性均相当。

关键词：心房颤动间隔封堵器左心耳介入治疗

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Hypophosphatemia is an independent risk factor for AKI among hospitalized patients with COVID-19 infection

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RENAL FAILURE 2021年第1期43卷 1329-1337页

作者： Chen, Zijin Gao, Chenni Yu, Haijin Lu, Lin Liu, Jialin Chen, Wei xiang, Xiaogang Hussain, Hafiz Muhammad Jafar Lee, Benjamin J. Li, Chuanlei Wei, Wenjie Huang, Yuhan Li, xiang Fang, Zhengying Yu, shuwen Weng, Qinjie Ouyang, Yan Hu, Xiaofan Tong, Jun Liu, Jian Lin, Li Liu, Mingyu Xu, Xiaoman Liu, Dan Song, Yuan Lv, Xifeng Zha, Yixin Ye, Zhiyin Jiang, Tingting Jia, Jieshuang Chen, Xiaonong Bi, Yufang Xue, Jun Chen, Nan Hu, Weiguo He, Cijiang John Wang, Huiming Liu, Jun Xie, Jingyuan Shanghai Jiao Tong Univ Inst Nephrol Sch Med Ruijin HospDept Nephrol 197 Ruijin Er Rd Shanghai 200025 Peoples R China Fudan Univ North Huashan Hosp Dept Nephrol Shanghai Peoples R China Shanghai Jiao Tong Univ Sch Med Ruijin Hosp Dept Crit Care Med Shanghai Peoples R China Shanghai Jiao Tong Univ Inst Resp Dis Sch Med Ruijin HospDept Pulm & Critical Care Med Shanghai Peoples R China Shanghai Jiao Tong Univ Sch Med Ruijin Hosp Dept Infect Dis Shanghai Peoples R China Houston Kidney Consultants Houston TX USA Houston Methodist Inst Acad Med Houston TX USA Shanghai Jiao Tong Univ Shanghai Gen Hosp Dept Nephrol 85 Wujin Rd Shanghai 200080 Peoples R China Wuhan Ninth Hosp Wuhan Peoples R China Wuhan Ninth Hosp Renal Dept Wuhan Hubei Peoples R China Wuhan Univ Renmin Hosp Radiol Dept Wuhan Hubei Peoples R China Wuhan Univ Renmin Hosp Renal Dept Jiefang Rd 238 Wuhan 430060 Hubei Peoples R China Shanghai Jiao Tong Univ Shanghai Gen Hosp Clin Res Ctr Shanghai Peoples R China Shanghai Jiao Tong Univ Sch Med Ruijin Hosp Dept Endocrinol & Metab Dis Shanghai Peoples R China Fudan Univ Huashan Hosp Dept Nephrol Shanghai Peoples R China Shanghai Jiao Tong Univ Ruijin Hosp Sch Med Dept Surg Shanghai Peoples R China Mt Sinai Sch Med Div Nephrol New York NY USA

Background This study sought to investigate incidence and risk factors for acute kidney injury (AKI) in hospitalized COVID-19. Methods In this retrospective study, we enrolled 823 COVID-19 patients with at least two evaluations of renal function during hospitalization from four hospitals in Wuhan, China between February 2020 and April 2020. Clinical and laboratory parameters at the time of admission and follow-up data were recorded. Systemic renal tubular dysfunction was evaluated via 24-h urine collections in a subgroup of 55 patients. Results In total, 823 patients were enrolled (50.5% male) with a mean age of 60.9 +/- 14.9 years. AKI occurred in 38 (40.9%) ICU cases but only 6 (0.8%) non-ICU cases. Using forward stepwise Cox regression analysis, we found eight independent risk factors for AKI including decreased platelet level, lower albumin level, lower phosphorus level, higher level of lactate dehydrogenase (LDH), procalcitonin, C-reactive protein (CRP), urea, and prothrombin time (PT) on admission. For every 0.1 mmol/L decreases in serum phosphorus level, patients had a 1.34-fold (95% CI 1.14-1.58) increased risk of AKI. Patients with hypophosphatemia were likely to be older and with lower lymphocyte count, lower serum albumin level, lower uric acid, higher LDH, and higher CRP. Furthermore, serum phosphorus level was positively correlated with phosphate tubular maximum per volume of filtrate (TmP/GFR) (Pearson r = 0.66, p < .001) in subgroup analysis, indicating renal phosphate loss via proximal renal tubular dysfunction. Conclusion The AKI incidence was very low in non-ICU patients as compared to ICU patients. Hypophosphatemia is an independent risk factor for AKI in patients hospitalized for COVID-19 infection.

关键词： COVID-19 proximal tubule acute kidney injury risk factors hypophosphate

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Metal-Free Mesoporous SiO₂ Nanorods as a Highly Efficient Catalyst for the Baeyer-Villiger Oxidation under Mild Conditions

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ACS SUSTAINABLE CHEMISTRY & ENGINEERING 2018年第5期6卷 5868-5876页

作者： Zhang, Xueyao Yang, Honglei Yang, Guangxue Li, shuwen Wang, xiang Ma, Jiantai Lanzhou Univ Coll Chem & Chem Engn Gansu Prov Engn Lab Chem Catalysis State Key Lab Appl Organ Chem SKLAOC Lanzhou 730000 Gansu Peoples R China

The development of efficient and environmentally friendly catalysts for oxidative reaction is of great importance in applied catalysis. In this work, a simple and environmentally benign approach for highly selective preparation of epsilon-caprolactone by oxidation of cydohexanone has been carried out, which employed metal-free mesoporous silica (mSiO(2)) nanorods as catalyst under atmospheric pressure. The metal-free silica catalyst was applied for the first time in the Baeyer-Villiger (B-V) oxidation reaction. It showed efficient catalytic performance for the B-V oxidation of various cyclic ketones and aliphatic ketones with O-2/benzaldehyde as oxidant. The catalyst could be easily separated from the reaction system by filtration and reused several times without significance loss of activity. Moreover, electron paramagnetic resonance (EPR) spectra of the reaction were obtained, indicating the existence of benzoyloxyl radical. The mechanism study of the reaction demonstrated that the super large surface area diluted the concentration of radicals and the adsorption of radicals could protect the radical species from inhibition.

关键词： Metal-free mSiO(2) nanorods Baeyer-Villiger reaction EPR spectran of mechanism study

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盘式封堵器封堵老年心房颤动患者大口径左心耳的安全性和有效性

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介入放射学杂志 2022年第10期31卷 958-961页

作者：王赛华郇强郝舒文罗俊武英彪朱茜方明田蓓顾薇宋湘宁忠平赵志宏上海健康医学院附属周浦医院心内科 201318

目的评价盘式封堵器应用于老年心房颤动(房颤)患者大口径左心耳的安全性和有效性。方法回顾性分析2018年5月至2021年6月在上海周浦医院接受LAmbre盘式封堵器封堵术治疗的老年房颤患者临床资料。78例左心耳开口直径≥31 mm患者为大口径组... 详细信息

目的评价盘式封堵器应用于老年心房颤动(房颤)患者大口径左心耳的安全性和有效性。方法回顾性分析2018年5月至2021年6月在上海周浦医院接受LAmbre盘式封堵器封堵术治疗的老年房颤患者临床资料。78例左心耳开口直径≥31 mm患者为大口径组,140例左心耳开口直径<31 mm患者为非大口径组。比较两组患者临床一般资料、术中参数、抗栓治疗方案及随访12(10,22)个月结果。结果大口径组女性占42.3%,年龄(75.8±9.1)岁,≥80岁患者比例为43.6%。大口径组盘式封堵器密封盘直径范围为32~40 mm,术后封堵器周边漏发生率显著高于非大口径组(P<0.05);器械相关血栓(DRT)发生率为13.3%(8/60),高于非大口径组4.2%(4/96)(P<0.05)。两组术后发生脑梗死、短暂性脑缺血发作、脑出血及死亡差异无统计学意义(均P>0.05)。结论老年大口径左心耳房颤患者接受盘式封堵器封堵治疗安全有效,术后封堵器周边漏及DRT发生率增加,但不影响临床预后。

关键词：心房颤动盘式封堵器左心耳封堵术不良事件

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Trends in global virtual land trade in relation to agricultural products

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LAND USE POLICY 2020年第0期92卷 104439-000页

作者： Qiang, Wenli Niu, shuwen Liu, Aimin Kastner, Thomas Bie, Qiang Wang, xiang Cheng, Shengkui Lanzhou Univ Coll Earth & Environm Sci Lanzhou Peoples R China Lanzhou Univ Inst Studies Cty Econ Dev Lanzhou Peoples R China Chinese Acad Sci IGSNRR Beijing Peoples R China Senckenberg Biodivers & Climate Res Ctr Frankfurtam Main Germany

Trade volume of agricultural products can be used to quantify the virtual land transfers between countries. This study assessed the virtual land trade (VLT) associated with the global trade of agricultural products using specific crop yield of exporting countries and gave insights in characteristics of different products and different countries. In addition, the features of trade connections were also displayed by network analysis. The results showed that the total virtual land within global agricultural trade increased from 128 million hectare (ha) in 1986 to 350 million ha in 2016, the average annual growth rate was 5.73 %. Increases in trade of oil crops contributed the largest share to this. The proportion of exported land area in total harvested land area increased for almost all categories of agricultural products. Countries engaged in global agricultural trade could be divided into three groups, net exporters, net importers and countries with balanced VLT. The net importers could be further divided into the countries with absolutely scarce land resources and the countries with relative scarce resources. All net virtual land exporters are the countries with more land resources per capita, such as the United States, Brazil and Argentina. Income growth and changes in diet structure are main factors driving increases in VLT. The VLT network became more complex over the study period, with the number of import and export nodes increasing continuously, and the cumulative distributions of export and import node strength following power law distributions. The major links and players within national, geographic, and economic groups also changed significantly over the study period. VLT has a deep impact on society, economy and environment, appropriate policies should be taken to make these interlinkages more sustainable for both importers and exporters.

关键词： Virtual land Agricultural trade Global trade network Trends Redistribution of land resources

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