运用风蚀仪进行风力侵蚀特征研究的实践

在10 m/s试验风速下,运用风蚀仪、降尘缸等风蚀测量仪器,对裸露、10%砾石覆盖、20%砾石覆盖3种地表状态的风力侵蚀进行了人工模拟试验,对比分析水土保持措施防风蚀的效果。结果表明:无论是累积输沙量、输沙率还是沉积量,3种地表状态均为裸露地表>10%砾石覆盖>20%砾石覆盖,尤其是20%砾石覆盖状态下远远小于裸地。因此,砾石覆盖对防止风力侵蚀的效果是明显的,并且覆盖度越大,防风蚀效果越显著。     

泾河张家山水文站水沙特性分析及工程实例

为合理评价和利用多沙河流水资源,基于张家山水文站1956年-2009年逐日降水量、径流量、输沙量和含沙量数据,分析张家山站水沙变化特征。各系列多年平均特征值表明:输沙量不均匀系数最大,7、8月输沙量占全年的81%;降水、径流主要集中在7-9月。统计年降水量、径流量、输沙量和含沙量分期年平均特征值,前三者时段均值呈减小趋势,含沙量时段均值波动变化。Mann-kendall秩次相关检验显示年降水量、径流量和输沙量的检验值分别为2.39、4.45、3.36,都大于0.05的置信水平,均有显著减小变化趋势。输沙模数时段均值减小,来沙系数时段均值增大。灰色相关度和双累积曲线分析表明:径流与输沙量、降水量相关性较好,径流与输沙量关联度为0.64,比径流与降水的关联度0.62稍大。最后,探讨泾恵渠渠首排沙闸工程,泾恵渠引水合理沙限为15%,排沙闸适宜排沙流量为200m3/s。研究结果可为泾惠渠渠首改建工程设计提供参考。     

能量密度对低温等离子体辅助催化转化柴油机颗粒物和NOx的影响

为了研究低温等离子体辅助催化后处理技术对柴油机有害排放物的作用效果,基于介质阻挡放电理论设计了低温等离子体（NTP）发生器,研究了NTP发生器工作电压随能量密度的变化关系。以涂覆γ-Al2O3的蜂窝状陶瓷为载体,采用柠檬酸凝胶法制备了LaMnO3催化剂,建立了NTP辅助LaMnO3催化试验系统。在台架试验基础上,研究了能量密度变化对NTP辅助LaMnO3催化技术转化（颗粒物）PM和NOx的影响规律。试验结果表明：在相同频率作用下,NTP发生器的能量密度随着工作电压的升高而增加;与原机相比,NTP辅助LaMnO3催化技术作用后NO浓度显著降低,NO2浓度显著增加,NOx浓度降低;随着能量密度的增加,碳烟转化效果越明显,碳烟的不透光烟度最高降低约83%。结果表明NTP辅助LaMnO3催化技术可有效转化PM和NOx,在柴油机排气后处理领域有着广泛的研究前景。     

小麦/玉米轮作体系中不同施肥方法下的养分淋溶排污系数测算

为粮田耕地污染监控预警及污染控制提供技术支持,以北京市房山区小麦/玉米轮作为研究对象,采用陶土头负压法,通过2年的田间小区对比试验,以不施肥处理为对照,分析比较优化施肥和常规施肥对淋溶液水质的影响,并测算不同施肥处理的排污系数。研究结果表明:不同的施肥处理氮素淋溶量占总养分淋溶的76%~82%,氮素淋溶中以硝态氮为主,占总氮素淋溶的60%~70%,最高可达到90%;在氮磷钾养分施入量相同的情况下,优化施肥处理在不同程度上降低了养分淋溶量,可使总氮淋溶量减少23%~31%,总磷淋溶量减少32%~46%,硝态氮淋溶量减少22%~36%,在降雨量大时,优化施肥处理可明显减少铵态氮的淋溶;经测算,小麦/玉米轮作农田耕地排污系数(产出每公斤农产品养分淋溶排出量)常规施肥处理总氮、总磷、铵态氮及硝态氮的排放量分别为687.2、3.25、0.22、440 mg,优化施肥处理的排放量分别为348、0.87、0.38、205.9 mg。     

Effects of changes in land use and land cover on sediment discharge of runoff in a typical watershed in the hill and gully loess region of northwest China

Land use plays a much more important role than other factors, such as climate, soil properties, topographic features, vegetation coverage, human activities and others, in affecting soil erosion and sediment discharge. In order to understand the effects of changes in land use on sediment discharge and to provide a theoretical basis for land use planning, management and ecological restoration, we used the controlled Qiaozidong watershed and the uncontrolled Qiaozixi watershed in the third sub-region of the Loess Plateau as examples and analyzed the effects of land use and land cover on the discharge of sediments. The results show that the impact of land use and land cover on the annual amount of sediment discharge is significant. Compared with the uncontrolled watershed during similar periods, the amount of sediment discharged from the controlled watershed was reduced by 44%, 75% and 86%, respectively, in wet, normal and dry years. In the controlled watershed, compared with the period from 1986 to 1994, the amount of sediments discharged was less during the period from 1995 to 2004. The impact of land use and land cover on sediment discharge demonstrated characteristics of seasonal fluctuation. The effects of sediment reduction in the controlled watershed were greater than those in the uncontrolled watershed in May and September. In the controlled watershed, the reduction effect coincided with the distribution of rainfall. The amount of discharged flood sediments is closely correlated with rainfall, rainfall intensity in a 60 min period and the volume of flood. The rainstorm-runoff process and the rainstorm-sediment discharge process demonstrate that land cover has a strong regulatory and control function in the flood process and sediment discharge in rainstorms. For the controlled watershed, given the same precipitation frequency distribution, the average amount of sediment discharged during the land use period from 1995 to 2004 was less than that during the earlier land use period from 1986 to 1994 under every recurrent period. __________ Translated from Journal of Beijing Forestry University, 2007, 29(6): 115–122 [译自: 北京林业大学学报]     

微灌毛管进口流量调节器应用的经济性分析

通过对一个滴灌系统安装与不安装毛管流量调节器的4个方案进行的实例设计,综合分析了各方案的工程造价和运行能耗,探讨了流量调节器应用的经济可行性,提出了流量调节器经济性分析与评价的方法,结果表明,微灌工程中,毛管流量调节器的成本对工程造价影响不明显,而允许工作水头下限值对工程能耗影响显著,如果所选毛管流量调节器的允许工作水头下限值大于其经济阈值,则使用流量调节器是不经济的,毛管流量调节器的型号、规格和工作参数的选择与使用,可参照列举的方法进行技术和经济性分析后确定．     

Ascospore release by <Emphasis Type="Italic">Venturia inaequalis</Emphasis> during periods of extended daylight and low temperature at Nordic latitudes

Darkness suppresses ascospore release in Venturia inaequalis, but the impact of light levels during the extended twilight and dusk that typify Nordic spring conditions is poorly understood. Volumetric spore traps were operated at two different locations in Norway over several years. During the season of asocspore release (approximately 1 April to 30 June), on 25 occasions when rain started during night (after 23:00 h and before 04:00 h) and leaves remained wet until at least midnight the following day, the cumulative percentage of spores trapped at sunrise did not exceed 1%, irrespective of temperature. Three hours after sunrise, cumulative ascospore release reached 0.8%, 3.0%, and 8.1% at temperatures of 0 to 5°C, 5 to 10°C, and >10°C, respectively, and 50% release occurred at 11, 9, and 8 h after sunrise. Additional field and laboratory studies indicated that the protracted dawn and dusk of Nordic latitudes, either alone or in combination with low temperatures, does not substantially alter previously reported patterns of ascospore release.     

排污权交易制度研究的理论基础

研究排污权交易制度的理论基础,是为了在理论上对其内涵有更为具体的理解和认识,在实践中有助于自觉而理性地对待和应用排污权交易制度。文章在相关文献的基础上,采用实证描述与规范研究分析方法,通过对环境问题产生的根源追溯,主要从环境外部性理论、公地悲剧理论、资源稀缺理论、市场失灵理论、科斯定理、政府失灵理论、制度变迁理论等方面探讨排污权交易制度的理论支撑。研究表明,没有固定的政府干预理论模式,也不存在完全的市场导向实践模式,任何模式都有发挥自身作用的空间。排污权交易制度是一个双赢的制度安排,折射了政府干预和市场化交易这两大学术思想的交融,是现代市场经济发展的趋势和必然结果,其背后是市场的自由运行,是政府角色和职能的转换,是经济发展制度保障的完善。     

不同频率下的泥石流体特征数值计算方法研究——以大寨沟流域为例

在泥石流定量研究中,泥石流流量、流速、泥石流规模是泥石流体最重要的特征值.能比较准确的确定泥石流这些特征数值既是泥石流计算中的关键问题,也是泥石流防治工程设计研究中的重要因素.利用雨洪法,首先比较一种或两种水文学的计算方法,择优来计算暴雨与洪水特征数值,然后利用暴雨与洪水特征数值来推算泥石流体各种特征数值.比如用暴雨洪峰流量以及配方法来计算泥石流流量,利用洪水总量来推算泥石流规模.     

新疆玛纳斯河水量波动与气候变化之间的关系

玛纳斯河发源于北天山中段,消失于准噶尔盆地西缘,是天山北麓流量最大的内流河.分析1954～2001年红山嘴水文站的流量资料及1986～2001年的石河子市降水资料、温度资料,得出近46年来玛纳斯河流量的变化规律;同时可以发现在一般情况下,玛纳斯河的降水与流量之间正相关,但在相对冷的年份,降水与流量的关系比较复杂,这是由于相对冷的年份,冰雪消融量减小,而抵消了降水引起的流量的增加;夏季温度的变化对玛纳斯河的流量影响作用较大.