Culturable bacterial diversity in hypolithic and peripheral soils in the west of the Hexi Corridor desert and its influencing factors

Microbes inhabiting the desert respond sensitively to environmental changes and may be an indicator for changes in the desert ecosystem.Hypolithic microbial communities in the desert play a vital role in ecosystem processes such as soil formation and organic matter accumulation.This study investigated and compared the culturable bacterial community structure and diversity in hypolithic and peripheral soils,and the interaction between bacteria and environmental factors.The bacteria were isolated using four different kinds of media and identified by 16S rRNA gene-sequence analysis.The numbers of culturable bacteria in the hypolithic and peripheral soils ranged from 3.0×104 to 3.6×105 CFU/g and from 6.5×104 to 5.3×105 CFU/g,respectively,indicating that the bacteria number in peripheral soil was higher than that in hypolithic soil.A total of 98 species belonging to 34 genera were identified,among which Arthrobacter,Bacillus,and Streptomyces were found dominantly and widely distributed.The community of culturable bacteria had obvious sample specificity,and the diversity in hypolithic soil was higher than that in peripheral soil.On the regional scale,the distribution of culturable bacteria and the environmental factors showed regular changes.On the local scale,the high heterogeneity of the hypolithic environment determined the specificity of the number and species of culturable bacteria.     

水资源约束下河西走廊的城市竞争能力与扩张幅度研究

基于西北干旱区河西走廊7个城市市区的水资源供应状况及其短缺程度和城市化进程加快与水资源短缺二者的矛盾关系,分析了在水资源约束下河西走廊城市竞争力和城市扩张的变动幅度等问题。认为河西走廊绝大多数城市"缺水又费水",城市发展具有明显的"旱生性"。在水资源约束下,城市扩张的总体特征表现为以总量扩张为主,"农转非"空间和用地拓展空间大,以高耗低效扩张为主,水土资源投入产出效益普遍低下,城市发展处在主靠资源开发拉动经济增长的低级阶段,扩张质量有待提高。为了确保城市的有序竞争与扩张,建议在城市建设过程中坚持以人为本,以水为生命线,以经济发展为动力,以城市规划为法定依据,先发展后扩张,量水依法优质扩张,突出城市建设特色与个性,确保城市可持续发展。     

基于蒙特卡罗模拟法的北京地区非典时空变化特征

采用专门研究不确定性变化规律的蒙特卡罗 (MonteCarlo)模拟法结合GIS ,研究北京地区非典时空变化的基本特征。北京非典时间变化的影响度指数结果表明 ,海淀区(10 6 6 6 6 7)、朝阳区 (6 6 92 31)、东城区 (5 974 36 )、西城区 (4 1794 9)和通州区 (3 6 410 3)等 5个地区占北京地区非典影响率的 72 8% ,其中海淀区就占了 2 5 % ,远郊区县的影响几乎为零。非典整体频数 /次数特征曲线表现出明显的偏正态分布 ,因此前期及时对公众预警并切断传染途径是预防体系的首要环节。非典空间分布表现出明显的圈层结构 ,并且具有西北-东南走向 ,因此非典的空间防御体系应该沿核心区向外设立几道防御圈层     

Recent deformation at the junction between the North Luzon block and the Central Philippines from ERS-1 Images

Abstract The transfer of the major part of the motion between the Philippine Sea Plate and the Sunda block is accommodated along a north-west shear wide zone partly on the Philippine Fault and partly on the Sibuyan Verde Passage Fault (SVPF) as indicated by global positioning satellite and geological data. Given the limited motion along the SVPF and the important motion along the Philippine Fault, as well as the necessity of a connection between these faults and the southern Manila Trench, a transtensional motion along the northeast-southwest Macolod Corridor (MC) may be predicted. We used synthetic aperture radar European remote sensing (SAR ERS-1) images to analyze the volcano– tectonic features of this area, because these images are sensitive to minute textural or topographic contrasts resulting from small effects of recent deformation. In addition, they allow us to determine accurately the shape of the base of volcanic edifices and to detect linear clusters of very small adjacent cones. The results presented herein allow us to extend the features recognized earlier to a larger MC. Large faults actually connect the Philippine Fault to the Sibuyan Verde Passage Fault all across the Taal Volcanic Field. In addition to extension along north-east faults, we identify an important component of left-lateral strike–slip underlined by fault scarps, dykes, alignments of volcanoes and pull-apart basins, accompanied by extension along north-south faults. A relative chronology of the fractures and volcanic edifices is proposed. When compared to the existing ages of the volcanics, an evolution scheme of the area may be proposed, according to which extension shifted from a nearly north-south opening between 5 and 2 million years to a direction close to east-west at Present. The early north-south extension existed in the Marinduque Basin and may have migrated northward and rotated to the present MC.     

绿洲农区土壤生产潜力初步研究——以河西走廊临泽样区为例

根据"中国土壤系统分类中基层分类研究"的要求,以河西走廊临泽样区为例,在前人研究资料的基础上,对河西走廊临泽样区耕地以土系为单元,进行了土壤生产潜力综合评价和初步研究,并得出结果:高潜力地,包括兰家堡系、倪家下营系,面积为8 936.582 hm²,占样区土地总面积的27.33%;低潜力地,包括东三村系、盘石营系、化音系、曹家庄系和五三村系,面积为2 483.251 hm²,占样区土地总面积的6.21%。     

河西地区新世纪人地系统优化与经济可持续发展的产业重点

在我国西部大开发战略实施过程中,河西地区充当着"开路先锋"的重要角色。在实地调研的基础上,提出了河西地区新世纪经济可持续发展的产业重点。农业产业重点是商品性畜牧业、保护性林果业、制种业、外销性蔬菜业和草产业,大力推进农业的产业化经营,建设外销型优质蔬菜基地、外销型优质制种基地和优质林果业基地,巩固现有的国家级商品粮基地,力争把河西走廊建成国家第二个农业高新技术产业开发区;工业产业重点是建设祖国最大的"镍都",铸造西北最大的"钢城",全面推进农副产品深加工转化与滚动增值,确保轻重工业协调发展;第三产业重点是大力发展生态旅游与"丝路"旅游,把旅游业培育成第三产业的支柱产业,把河西建成中国西部生态旅游示范区。     

中麻黄在河西栽培的影响因子及固沙效益研究

水分和土壤盐分是影响中麻黄在河西沙区分布、丰产栽培的主要因子。随着西去,降雨量减少,干燥度增加,中麻黄群落递减;中麻黄幼苗具有一定的耐盐性,成苗后耐盐能力显著增强,当土壤含盐量在0.82%时,出苗率降为41%,盐害死亡率48.8%;年灌水量以1500~2250 m³·hm^-2为宜,施N、P肥可增加中麻黄高生长和分蘖枝数。中麻黄是河西沙区生态建设的重要植物,其植丛的固沙能力强,通过积沙固沙可形成固定、半固定沙地。依据中麻黄生长规律,集约栽培,减缓对天然植被的破坏,使其发挥最大的经济效益和生态效益。     

环境微量元素对甘肃河西地区胃癌发病的影响

环境物质中的微量元素水平与胃癌之间存在相关联系,甘肃省是胃癌高发区,对甘肃省河西地区胃癌患者生活饮用水及土壤微量元素进行了相关性研究.结果表明:河西地区水土的Fe含量高于对照组,高浓度游离Fe有利于癌细胞的快速繁殖,摄入高浓度的离子Fe对机体有毒害作用,是导致胃癌发生的一个重要因素.环境中Zn水平低可能是胃癌发生的癌前因素,Se水平与癌症生病率呈负相关,河西地区环境中镓含量较低,可能导致机体内微量元素的不平衡,促使胃癌的发生.     

河西金矿综合找矿信息研究

通过系统研究矿床地质，地球化学及地球物理综合信息，地球物理电法可探深1000米，利用平行测深剖面，作成包含成矿构造破碎带的三维立体模型，指导找矿，取得较好效果。     

荒漠绿洲PRED系统特征与可持续发展定量研究

荒漠绿洲PRED系统是一个相当脆弱的系统，自然灾害频繁、水分失衡导致的生态风险大。在分析其特征的基础上，建立了衡量可持续发展的指标体系并运用层次分析法得出了这些因子对绿洲PRED系统可持续发展的权值，影响最大的前三位因子是：人均水资源量、绿洲化面积、人口素质、其权值分别为0.124、0.077、0.062。计算了河西走廊20个县（市、区）的SDI，排在最前面的依次是：萧北蒙古族自治县、嘉峪关市和玉门市、金川区，其SDI分别为0.437、0.406、0.405，排在最后面的依次是：古浪县、民勤县、天祝藏族自治县，其SDI分别为0.150、0.213、0.217。分析了这种格局产生的原因并提出了相应对策。