农业生态补偿的国际经验及启示研究

由于长期的粗放型农业经营模式,中国农业生态系统遭到了极大破坏.根据农业发达国家经验,农业生态补偿是保护农业生态环境,推动农业可持续发展的重要途径.对美国、欧盟、日本等国家的农业生态补偿做法进行经验总结,包括土地休耕计划、农业环境补贴、生态农业认证等.基于国际先进经验,提出相关政策建议,包括健全农业生态补偿法律法规、完善农业生态补偿的投融资模式、明晰自然资源产权关系、因地制宜制定补偿标准等.     

桂西南喀斯特区域群落主要环境因子及稳定性对飞机草入侵的影响

为揭示桂西南喀斯特区域群落主要环境因子及稳定性对飞机草（Eupatorium odoratum）入侵的影响,本文通过对群落生存状况、土壤环境因子的调查分析,研究群落的稳定性特征,探讨不同植物群落对外来入侵种飞机草生长扩散的影响。结果发现：植物群落内本地种盖度、群落高度等与飞机草的盖度和多度呈极显著的负相关关系,说明本地种的生长能对飞机草的入侵产生显著影响,其中光因子可能是影响飞机草生长的主导因子和限制因子;本地物种多样性对飞机草的盖度和多度影响也较显著,说明本地种多样性能有效抵御飞机草入侵;人为干扰对飞机草的盖度和多度则呈极显著的正相关关系,说明干扰能促进飞机草的入侵;土壤速效氮含量、土壤含水量、有机质含量和与飞机草的盖度和多度的关系均呈显著负相关关系,可能是由于群落内肥水充裕程度与调节飞机草生长的主导因子光水平呈负相关关系造成的。群落的稳定性与飞机草的盖度和多度呈极显著的相关关系,说明稳定性较高的群落更能有效的抵御飞机草的入侵,稳定性较低的群落更容易受到飞机草的入侵。     

建筑工程施工基坑边坡支护安全--土钉墙支护措施浅谈

本文介绍了土钉支护原理,阐述并分析了其不占地表空间,施工简易,成本较低,能够保持边坡土体稳定,满足结构地下施工安全要求等优点.     

兰州农村面源污染现状及防治对策分析

文中在兰州统计年鉴的基础上,根据面源污染来源,分析了农业、畜牧业、生产和生活活动的危害,初步估算了主要面源污染物的流失量。并根据兰州市农村具体情况提出了相应的保护和控制措施,旨在为解决农村面源污染问题和保护农村生态环境提供借鉴。     

武江大桥桥址区岩溶灾害综合勘察方法研究

在武江大桥桥址区岩溶灾害勘察的基础上,研究了高密度电法和跨孔地震波CT方法在岩溶勘察中的应用,并且勘察结果与钻探验证进行了对比,得出高密度电法和跨孔地震波CT适用于岩溶勘察的结论,并讨论了其他勘察方法在岩溶地区的适用性和局限性。     

乙烯消减盐抑制苜蓿种子萌发的机理研究

0．25mol/L的NaCl胁迫下的苜蓿种子转变1－氨基环丙烷－1－羧酸（ACC）和乙烯利为乙烯的能力明显降低。加入外源乙烯能引发受NaCl胁迫48h的苜蓿种子迅速萌发,但对种子内的Na^ 含量无明显影响。在种子吸涨过程中,外源乙烯对受NaCl胁迫的种子的水分吸收也无影响。外源乙烯能显著地提高NaCl胁迫下种子的呼吸速率和ATP含量。对乙烯消减盐抑制苜蓿种子萌发的作用机理进行了讨论。图6表1参21     

Effects of high dose copper on plant growth and mineral nutrient (Zn,Fe, Mg,K, Ca) uptake in spinach

Loessal soil is one of the main cultivated soils in northwest China. Part of its distribution area was irrigated with industrial wastewater in past three decades. This caused heavy metal contamination in the soil. It had induced toxicity on crops and also threatened local human health for now. Based on a field plot experiment, effects of different Cu concentrations (from 45 to 2000 mg kg^?1) in loessal soil on spinach plant growth and uptake of mineral nutrients (Zn, Fe, Mg, K, and Ca) by spinach were investigated. The Cu addition increased available concentrations of mineral nutrients in loessal soil and concentrations of Cu, Zn, Mg, and Ca in roots. The translocation of mineral nutrients from roots to leaves was inhibited under Cu addition, inducing their decrease in leaves. The EC₁₀ and EC₅₀ of soil Cu in relative dry weights of leaves were 240.33 mg kg^?1 and 1205.04 mg kg^?1, respectively. The PLS-PM analysis showed that available concentrations of nutrients in soil were only affected by Cu in soil positively, nutrients in roots were mainly affected by Cu in soil and Cu in leaves positively, nutrients in leaves were mainly affected by Cu in roots negatively, translocation of nutrients in spinach and plant growth were principally affected by Cu in leaves negatively, and the total effect of Cu in leaves on nutrients in roots and leaves, translocation of nutrients in spinach, and plant growth was the highest. Our results indicated that the phytotoxicity of Cu including spinach growth inhibition and mineral disorder in spinach was mainly affected by the Cu concentrations in leaves.