水利工程施工成本的控制

施工成本是工程成本控制的主要内容,水利水电工程施工成本有效控制是工程施工管理的核心,如何实现水利水电工程施工成本有效控制显的尤为重要。只要科学地组织和规划,采取适当的控制标准,严格的按规章实施,工程施工成本的控制就会取得良好的效果。     

Water Extractable Trace Elements in Poultry Litters and Granulated Products

Poultry litter contains many trace elements such as As, Cu, and Zn, and its land application may lead to the accumulation of these elements in soils, especially near the soil surface. The objectives of this study were to determine the total amount of trace elements and evaluate the effect of litter granulation and various litter to water extraction ratios on water extractable trace elements in 8 raw and granulated litter products. Granulated litters that contained urea, dicyandiamide, or hydrolyzed feathermeal had significantly lower contents of total As, B, Cu, Mn, and Zn than untreated litters because of the dilution of litters with additives. Trace element concentrations (mg/L) in the water extracts of the various poultry litters generally decreased when extraction ratios (litter to water) shifted from 1:10 to 1:250, or as the amount of poultry litter decreased with a constant water volume (200 mL). But, the water extractable content of trace metals (mg/kg) generally increased from an extraction ratio of 1:10 to 1:200, with values similar at 1:200 and 1:250 extraction ratios. Based on our results, we suggest using a 1:200 extraction ratio when evaluating water extractable As, Cu, and Zn in poultry litters. The estimated land application rates of trace metals, when poultry litter is applied on the basis of total P content, were considerably lower than the trace metal loadings allowable under the current environmental regulations governing biosolids and other materials with measurable amounts of trace metals. The laboratory water extractions of poultry litters and granulated products have increased our understanding of the potential risks to water quality posed by the land application of poultry litter and will contribute to the development of base knowledge needed to define land application practices that are protective of soil and water quality.     

阿鲁科尔沁旗紫花苜蓿需水规律与灌溉定额

为了给阿鲁科尔沁旗紫花苜蓿(Medicago sativa)灌溉提供科学依据,利用1984-2013年30年气象数据,采用联合国粮农组织推荐的彭曼-蒙特斯公式法,研究了阿鲁科尔沁旗紫花苜蓿需水规律和灌溉定额。结果表明,阿鲁科尔沁旗紫花苜蓿第1茬、第2茬、第3茬、第4茬、生长季、非生长季和全年需水量分别为221、187、169、179、755、70和825mm,需水强度分别为4.3、4.7、4.1、2.5、3.7、0.4和2.3 mm·d~(-1),灌溉需水量分别为194、118、66、131、508、56和564mm,灌溉定额分别为228、139、78、154、598、66和664 mm。     

山羊、水牛感染肝片吸虫后淋巴细胞自然杀伤活性动态变化

自然杀伤 (NK)活性是在细胞水平反映机体天然免疫力的重要指标之一。本实验以SP2 / 0细胞为靶细胞 (即效应细胞 ) ,采用乳酸脱氢酶(LDH)短程释放法测定人工感染肝片吸虫的水牛和山羊的外周血液中淋巴细胞的NK活性动态变化。从测定结果的相对值来看 ,发现山羊在感染肝片吸虫后NK活性有 2次高峰 ,推测与虫体的发育或感染山羊的免疫状态有关 ;2个感染组 (Ⅰ ,2 0 0个囊蚴 /只 ;Ⅱ ,50 0个囊蚴 /只 )的变化趋势表明 ,感染量与NK活性无相关关系。感染水牛的NK值仅略高于对照组 ,无明显的高峰。而绝对值结果又反映出不同动物的NK活性有差异 ,水牛的NK活性比山羊高 ,说明水牛对肝片吸虫的天然免疫力比山羊强     

Assessing Knowledge Production for Agrosilvopastoral Systems in South America

In recent decades agroforestry has undergone significant development in Latin America. South America generates the most scientific research on the topic in the region. We conducted a comprehensive review and analysis of knowledge production for South American agroforestry that includes livestock grazing, known as agrosilvopastoralism (AS), examining how different sociopolitical factors such as sources of funding, institutional priorities, and international cooperation can bias the direction and objectives of scientific research. We assessed the major attributes of scientific publications on the topic (25 articles per country; overall n = 210) and the potential factors underlying the processes of research and development in the region. The tree component was the most studied, while the livestock component received less attention. Studies were mainly focused on the production of goods and services (monetary or nonmonetary approaches), except in Brazil, where conservation was the major study objective. Stakeholders were involved in more than half of the studies (60%), and they were mostly ranchers and local producers. More than half (70%) of the studies offered recommendations based on their results, and such recommendations were mostly concerned with the management of agrosilvopastoral system components. In general, studies were led just as often by local as foreign first authors and coauthored by more than three people as part of interinstitutional working groups. Brazil, Argentina, Colombia, and Chile had more frequent cooperation among institutions and countries but mainly used their own funding. In contrast, Bolivia, Ecuador, and Peru had almost 100% of their studies supported by foreign countries (North America and Europe). Countries with greater internal funding of research generated more long-term studies. Besides this, two clear trends were detected: 1) conservation and social aspects were mainly supported by sources from external countries led by foreign principal investigators, and 2) production issues were supported from sources within countries and supported high levels of cooperation among institutions.     

不同土地利用方式下表层土壤大团聚体特征

土壤大团聚体含量能表征土壤结构稳定性,反映土壤结构变化趋势。本研究在辽河干流中下游流域主要沙化区分析湿地、林地、农田和草地4种土地利用方式对0-20cm土层土壤大团聚体(0.25 mm)含量和稳定性的影响,及各粒径大团聚体的空间异质性,并进行空间插值模拟其分布。结果显示,农田土壤团聚体破坏率最大,达到46.98%,林地最小,为26.36%;依据土壤水稳性大团聚体含量、团聚体颗粒平均重量直径和几何平均直径,评价土壤结构稳定性强弱为湿地林地农田草地;4种土地利用导致土壤大团聚体稳定性差异显著(P0.05),湿地和草地之间的差异性最显著;湿地土壤结构相对最好,其次是林地和农田,草地相对最差。本研究结果可为辽河干流流域土地沙化程度评价及分区治理提供参考依据。     

云南水牛资源及利用

云南水牛资源丰富,发展潜力大,本文简要论述了云南水牛的生态分布,体形外貌,遗传多样性及其生产性能,并指出云南水牛由役用型向役,肉,乳兼用型的利用方向发展。     

甘肃省坡耕地利用状况与退耕还林还草技术对策研究

对甘肃省坡耕地的利用状况及其退耕的可行性进行了较为全面的分析,按照因地制宜的原则,将退耕区域划分为陇中黄土丘陵沟壑区、陇东黄土台塬区、山高坡陡的陇南山区与河西防风固沙区四大区,并就各区退耕后的还林还草方式进行了具体的论证,提出了15°～25°和25°以上坡耕地退耕还林还草的具体技术对策。     

伊犁绢蒿荒漠草地围封后的土壤动态

本研究对伊犁绢蒿(Seriphidium transiliense)荒漠草地的土壤理化性质及光谱进行测定,探讨围封对土壤理化性质的影响和草地光谱的响应。结果表明,土壤含水量在各土层随植物生长期呈递减趋势,5月与9月土壤含水量随围封年限的延长总体上呈增加趋势,并对群落光谱和土壤含水量间关系进行建模,R2=0.63;土壤有机质随封育年限增加呈升-降-升的趋势,围栏内外有机质差值在5月随封育年限的增加而增加,封育7年、10年草地有机质差值,植物生长期内呈线性递减。通过室内土壤光谱及野外裸地光谱对土壤有机质进行建模,均取得较好效果,R2分别为0.64与0.38。研究表明,草地土壤含水量及有机质对于草地恢复状况较为敏感,可用于该类草地封育状况的监测。     

覆膜垄沟集雨种植对老芒麦高度和密度的影响

研究了北方农牧交错区垄沟集雨种植措施对老芒麦Elymus sibiricus生长发育的影响。覆膜垄沟集雨种植可以使有限降雨在沟内富集累加,垄面径流效率达到80%左右。老芒麦2008和2009年营养生长阶段,处理间高度差异显著。2008年处理1和CK相比,株高提高33.5%~61.3%;处理2和CK相比,株高提高20.1%~44.1%,处理1与处理2相比,株高提高9.2%~16.2%。2009年处理1与CK相比,株高提高93.2%~116.4%;处理2与CK相比,株高提高65.4%~82.3%;处理1与处理2相比,株高提高12.1%~19.4%。处理1、处理2与CK三者在密度方面差异不尽相同,总体表现出处理2和处理1老芒麦密度高于CK,2008年密度动态变化和单株分蘖数变化保持一致,2009年返青后,呈现出整体略微下降趋势,趋于稳定。