共查询到18条相似文献,搜索用时 66 毫秒
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研究了三峡库区澎溪河落干期消落带不同地点、不同高程段、不同土地利用方式下土壤硝化强度及影响因素。结果表明,研究区域消落带硝化强度范围为0.76~9.76 mg/kg·d,平均值为3.76±0.76 mg/kg·d,明显低于国内其他研究区域土壤硝化强度。澎溪河消落带从上游汉丰湖到下游黄石,土壤硝化强度呈现递减的趋势。随着高程的增加,消落带土壤硝化强度逐渐降低,但没有显著差异(P >0.05)。消落带不同土地利用方式中,河滩地土壤硝化强度显著高于耕地土壤硝化强度(P<0.05),是耕地土壤硝化强度的1.82倍。消落带土壤硝化强度与土壤pH值呈显著正相关(P<0.05),与有机质含量及亚硝化菌数量呈极显著正相关(P<0.01),周期性的淹水影响了消落带土壤pH值和有机质含量,从而影响了消落带土壤硝化强度。 相似文献
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民权县近河道沙土区属于风沙地貌,土壤质地松散,适宜种植果树与花生。分析了该区的特点,提出相应的农业发展对策。 相似文献
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洞庭湖红壤坡地玉米生态拦截技术对产量和径流氮磷的影响? 总被引:1,自引:0,他引:1
坡地氮磷流失是洞庭湖农业面源污染的重要来源。此研究以湖南省湘阴县红壤坡地土壤为研究对象,通过田间小区试验,探讨了生态拦截技术对玉米产量、化肥利用率和氮磷流失量的影响。结果表明,生态拦截技术能有效减少地表径流量和泥沙流失量,径流量减少了5.7%~17.1%,而泥沙流失量减少了40.1%~45.6%。拦截氮磷效果显著,径流中总氮、总磷的去除效果分别达到26.5%~44.9%和29.3%~33.1%。生态拦截处理对玉米产量均表现出增产,比顺坡玉米提高了4%~8.1%;并一定程度提高NP化肥肥效和肥料利用率。 相似文献
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吉林省湿润冷凉区玉米优质高产高效生产制约因素及对策 总被引:55,自引:0,他引:55
玉米是吉林省湿润冷凉区的主要粮食作物,为提高玉米优质高产高效生产,通过国家丰粮工程“九五”至“十二五”玉米大面积综合配套技术集成研究,提出解决制约因素的对策,为保证该区域玉米高产、稳产、优质、高效提供有力的技术支撑。 相似文献
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日平均气温是反映气候特征的主要指标之一,计算日平均气温的方法有很多种,为了弄清不同的计算方法对日平均气温的影响,笔者对河北省5 个国家基准站的多年逐时气温资料分别进行极值平均、4 次平均、8 次平均3 种计算方法,统计日平均气温并与实际日平均气温进行对比分析。结果表明:3 种计算方法得出的平均气温序列与实际平均气温序列相关性较高,相关系数高达0.9 以上。气温平均值8 次平均最接近于实际日平均气温,平均偏低0.0052℃;极值平均比24 次平均偏高0.4568℃;4 次比24 次平均偏低0.1789℃。增温速率24 次平均最小,24 次平均比4 次平均的气温增温速率偏低0.001~0.03℃/10 a。3 种计算方法的估计精度在10-7和10-4之间,精度较高。在保证资料长度及测站数量的前提下,几种方法均能很好地代表气候的变化趋势。 相似文献
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经济危机导致了第二次世界大战的爆发。目前,由美国次贷危机到金融危机,再到全球性金融危机和经济衰退,是一个快速演变的过程。而经济衰退和经济危机只是量的不同,在本质上惊人相似。世界性金融危机产生于美国次贷危机,对我国的影响表现在出口、投资、金融等领域。应对金融危机,我国应实施积极的消费政策、加大投资力度、优化投资结构、加大鼓励出口的政策力度。 相似文献
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为了解三峡库区花岗岩母质不同经济林模式的土壤养分状况,研究了各模式下土壤pH、有机质、全量养分和速效养分的特征,并利用主成分分析法对不同模式的土壤质量进行了综合评价。结果表明,除土壤pH外,经济林土壤有机质、全氮、全磷、全钾、碱解氮、有效磷、速效钾等含量的变异较宽,为中等变异。随土壤层次的增加,各模式下土壤有机质、全氮、速效氮、速效磷和速效钾含量呈递减趋势,而全磷和全钾则存在不规律变化。土壤有机质、全氮和速效钾对经济林土壤质量的高低产生着主要作用,土壤养分综合排名表现为柑橘(精细管理)>柑橘(常规管理)>板栗林>茶园。因此,利用生物措施和精细化管理措施,可有效提高该区域经济林的土壤质量。 相似文献
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Estimation of the N and P Contributions to the Water Quality of the Three Gorges Reservoir 总被引:1,自引:0,他引:1
The elements N and P are crucial to the water quality of Three Gorges Reservoir. After the present situation and characteristics of N and P pollutions analyzed and statistical method, flux method and modeling method adopted to estimate the quantity of N and P from upstream and reservoir area, the pollution loads of point and no-point pollution source, the conclusion that the main source of N and P pollutants are from both upstream of Reservoir and non-point pollution. 相似文献
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In this paper, the possible geological disasters in Three Gorges Reservoir Area are reviewed. Firstly, the types of geological disasters are classified and their influencing factors and growth characteristics are analyzed, then the damages, which have happened in this area up to now, are listed. On this basis, five aspects of dangers brought by geological disasters to society and economic environment are analyzed. Finally, a conclusion was drawn that the geological disasters in Three Gorges Reservoir Area have done some harms to this area and the situation becomes worse than before. So some reasonable measures should be taken quickly. 相似文献
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三峡库区支流域澎溪河浮游动物的季节性变化与水质评价 总被引:1,自引:1,他引:0
为研究三峡库区北岸最大支流澎溪河中浮游动物与水质状况的关系。本研究分别于2009年春季(3月)、夏季(7月)在澎溪河流域上游至下游5个河流断面进行采样,对水体中浮游动物的种类及数量进行监测,并应用Margalef丰富度指数(d)、Shannon-Wiener指数(H)和Pielou均匀度指数(J)对水体营养状况进行评价。研究发现:使用浮游动物评价水质状况得出的结论与营养水平评价结论存在较大差异,基于浮游动物种类及优势度评价得出的水质富营养化程度轻于基于营养盐的评价。 相似文献
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After the dam of the Three Gorges is built, the raising water will inevitably cause the revival of the part of ancient landslide and the generation of new landslide ,which will influence the town development and traffic safety in the Three Gorges Reservoir Area. In the light of the specific conditions of the Three Gorges Reservoir Area, this paper, taking Fengdu's MingShan landslide in Chongqing for an example, has considered ten typical calculative projects, offered the correspondent load systems acting on the sliding mass and put forward the analytical and calculative method to evaluate the stability of a landslide. The ten typical calculative projects include dry season(natural state), raining season (rainstorm or rain for a long period of time), dry season and water level (175m ) of the reservoir, raining season and water level (175 m) of the reservoir, dry season and earthquake, raining season and earthquake, dry season and water level (175 m ) of the reservoir and earthquake, raining season and water level (175 m) of the reservoir and earthquake, dry season and water level lowered from 175 m to 145 m, raining seasons and water level lowered from 175 m to 145 m, and so on. 相似文献
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The present study is to investigate the differences of Hg,Cr,Pb,Cd and Zn contents among water area ecology stystems of the three gorges Reservoir from water,dirt mud of the bottom and benthic fishes.The result show that content distribution of trace elements is:dirt mud of the bottom>benthic fishes>water;content distribution of trace elements in benthic fishes is:viscera>muscle>bone.The distribution factor of dirt mud of the bottom versus water,adsorption coefficient of benthic fishes versus dirt mud of the bottom and enrich coefficient of benthic fishes versus water is constant value in three Gorges Reservoir.Mercury is harm element to human in food chain.Besides,transform model of food chain in trace element are studied. 相似文献