秦巴山区小流域综合治理对洪水的作用过程分析

采用小流域平行对比法,分析秦巴山区小流域的次降雨洪水过程,研究了水土保持综合治理对小流域洪水的作用过程。结果表明,水土保持综合治理能够有效地延迟峰现时间30~60 min,对于不同的降雨量、降雨强度,其削减洪峰流量的程度不同。其中削减洪峰流量14%~90%,使径流系数降低25%~71%。调节降雨径流的年内分配,使枯水期流量增大,汛期流量减小。     

Effects of microhabitat diversity and geographical isolation on oribatid mite (Acari: Oribatida) communities in mangrove forests

The effects of microhabitat diversity and geographical isolation on the structure of oribatid communities were studied in mangrove forests on the Ryukyu Islands of Japan. The study took place at three sites on two islands 470 km apart. Oribatid mites (Oribatida) were extracted from leaves, branches, bark of trunks (0-50, 50-100, and 100-150 cm high) and of knee roots, and from forest-floor soil and littoral algae, each defined as a microhabitat of oribatid mites. At the 0-50 cm height, the species composition of the oribatid communities on the knee-root bark and the bark of trunks of Bruguiera gymnorrhiza differed significantly from that on the other microhabitats. This difference was attributed to tidal flooding of the mangrove forests. Cluster analysis showed that oribatid communities in the same microhabitat at different sites tended to be more similar than those on different microhabitats at the same site. This implies that the species composition of oribatid communities in mangrove forests is more likely to be affected by factors responsible for microhabitat diversity (characterized specifically by the flooded trunks) than by geographical distance between the islands.     

基于元胞自动机的城市地表积水模拟研究

[目的]对城市地表水文产汇流时空过程进行模拟研究,以期为城市排水防涝应急决策提供依据。[方法]针对城市地表覆盖破碎性和地形复杂性的特征,构建基于元胞自动机(CA)的城市地表积水模型,结合水力水文学原理定义元胞及其规则。[结果]与传统统计经验模型、物理模型相比,该模型避免了汇水区划分、水流路径确定、参数提取等数据预处理问题,以广州市番禺区富华东路段区域作为试验区进行参数率定及模型验证,根据规则更新每个元胞的状态参数可获得任意时刻地表积水量、径流量和水流。[结论]该CA模型可以准确模拟地表水流时空分布及其变化,模拟结果可靠、表达直观;通过雨水口不同排放量模拟和常用数学模型对比分析表明,CA城市地表积水模型在城市内涝模拟中具有良好的实用性及易操作性。     

洪涝灾害导致水稻减产预测研究

采用数理统计的方法,对杭嘉湖平原的洪涝灾害导致水稻减产的规律作了分析与探讨,得出了洪涝灾害后水稻减产预测表。     

VE型喷油泵及其调速器的技术状态和调整参数对柴油机工作性能的影响

分析了VE型喷油泉调整技术参数对发动机功率影响的原因。     

节水灌溉对水稻产量和品质影响的荟萃分析

【目的】 与持续淹水灌溉相比,节水灌溉能够提高水分利用率。但是,节水灌溉对水稻产量和品质的影响尚不清楚。本研究采用Meta分析以探明节水灌溉对水稻产量和品质影响的综合效应。【方法】 在本研究中,以持续淹水灌溉为对照,节水灌溉为处理,筛选出了34篇文献,建立了包含263对观测值的数据库。利用Meta分析方法,针对不同试验类型、节水灌溉类型、种植制度、水稻类型、节水灌溉时期、土壤全氮、土壤质地、氮肥施用量及施用次数,探究了节水灌溉对水稻产量和品质的影响。【结果】 从总效应来看,与持续淹水灌溉相比,节水灌溉对水稻产量和品质均无显著影响。从不同的节水灌溉类型来看,与持续淹水灌溉相比,轻度节水灌溉显著提高了稻米糙米率（+0.9%）、精米率（+1.5%）和整精米率（+2.3%）,对水稻产量、垩白粒率、垩白度、长宽比、直链淀粉、胶稠度和蛋白质含量无显著影响;但是,重度节水灌溉显著降低了水稻产量（-22.1%）、糙米率（-2.7%）、精米率（-2.7%）和整精米率（-3.6%）,同时显著增加了稻米垩白粒率（+28.0%）和垩白度（+46.7%）,对稻米长宽比、直链淀粉、胶稠度和蛋白质含量影响不显著。此外,从不同的种植制度来看,与持续淹水灌溉相比,在我国双季晚稻区进行节水灌溉显著降低了稻米蛋白质含量（-9.8%）;而在双季早稻区、中稻区和单季稻区进行节水灌溉对稻米蛋白质含量影响不显著。【结论】 与持续淹水灌溉相比,轻度节水灌溉显著提高了稻米加工品质,对水稻产量、外观品质、蒸煮食味品质和营养品质影响不显著;重度节水灌溉显著降低了水稻产量、加工品质和外观品质,对蒸煮食味品质和营养品质影响不显著。本研究结果为评估节水灌溉对水稻产量和品质的影响提供了数据支撑。     

水淹程度对滩地枫杨主要力学性质的影响

研究结果表明,滩地枫杨各项力学指标基本上都是水淹1月(第l组)比水淹2月(第2组)大,但按材质等级来评估滩地枫杨木材材质便发现枫杨木材材质均在中等偏下,差异分析表明在0．05水平上差异显著。对枫杨木材主要物理力学指标作主成分分析,结果说明了木材干缩性是滩地枫杨木材的第一主成分,称为干缩指标;而力学强度为第二主成分,称为强度指标。     

高浓度沼液淹灌土水系统中氮、磷和有机物的动态变化

通过室内静置培养模拟试验,研究了高浓度沼液淹灌稻田土壤后上覆水和土壤中氮、磷和有机物的动态变化特征。结果表明,全沼液淹灌处理的上覆水中总磷和NH+4-N浓度分别在30 d和50 d内降低到允许排放标准以下;降低灌溉沼液的浓度,可缩短排放达标所需时间;但硝态氮浓度经过迅速下降后又会显著升高,全沼液灌溉处理100 d后,上覆水中NO-3-N的浓度比灌溉初期提高了44.9%。灌溉沼液中污染物浓度的降低,主要是降解和挥发作用的结果,只有少部分留在土壤中。因此,在水田休闲期进行高浓度的沼液淹灌,不仅可以消解和净化沼液中污染物质,还能有效改善土壤养分性质,不会引起土壤中氮、磷和有机物质的过量积累。     

Effect of winter-flooding on methanogenic archaeal community structure in paddy field under organic farming

Paddy field is a major emission source of methane. Methane is the terminal product of anaerobic decomposition of organic matter and generated by methanogenic archaea under flooded conditions in paddy fields. This study aimed to reveal the effect of winter flooding on methanogenic archaeal community structure in paddy fields of Andosols under organic farming. Soil samples were collected from experimental paddy fields in the Field Science Center, Tohoku University, for two years. They were under flooding conditions during winter with organic farming, under non-flooding conditions during winter with organic farming and under non-flooding conditions during winter with conventional farming (non-organic farming). Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis of methanogenic archaeal 16S rRNA gene revealed that the DGGE patterns were nearly the same irrespective of the treatment and sampling times. Twenty-three bands were observed from each treatment and 4, 13 and 6 sequences were closely related to Methanomicrobiales, Methanosarcinales and Methanocellales, respectively. Real-time quantitative PCR analysis indicated that the abundance of methanogenic archaeal 16S rRNA gene and mcrA gene, encoding α subunit of methyl-coenzyme M reductase, was not significantly different among the paddy fields. This study first revealed a methanogenic archaeal community in an Andosol paddy field and showed that the community was not affected by winter flooding under organic farming.     

水淹胁迫对消落带竹柳(Salix hybrid)幼苗的形态结构和生理生化特征的影响

探究水淹胁迫对竹柳的形态、生理指标及解剖结构的影响,为三峡库区消落带植被修复提供参考数据。选择长势一致的当年生竹柳扦插苗进行水淹处理,进行半淹组(SsG,水淹没植株根茎,在第一片叶以下)、全淹组( SG,水分淹没植株最顶端叶片)和对照组(CK,不水淹)处理,210天后,测定其生长指标、生理指标,并做根系切片观察解剖结构。结果表明,水淹后SsG组茎高显著高于另外2个组,茎上有很多凸起而肥大的皮孔,在茎基部形成了大量的气生根,根系数显著高于CK组,叶片呈狭长的线状,叶长宽比显著增加,SG组茎高、根系数均显著减少,叶片变小卷曲,增厚变脆微透明,颜色发红,由披针形变成椭圆形,叶长宽比显著降低；水淹后SsG组叶绿素含量与对照相比都呈上升趋势,SG组呈下降趋势,两种水淹处理叶绿素a/b的值都显著上升；水淹后SsG组叶和根中可溶性糖、叶中可溶性蛋白含量、根和叶中脯氨酸(Pro)含量与CK都无显著差异,只有根系中的可溶性蛋白显著低于CK,SG条件下可溶性蛋白和可溶性糖含量不管是叶还是根中都显著降低,而Pro含量显著上升；水淹后SsG组根系表皮层稍不完整,部分瓦解,皮层细胞间隙扩大,通气组织形成,SG组根系组织细胞受到明显损害,周皮及皮层细胞大部分解离,木质部细胞排列相对松散、细胞变大,髓射线不明显。说明SsG在一定程度上促进了植物地茎的生长,而SG具有显著的抑制作用,建议将竹柳配置在消落带高程的上半部分区域,能较好地能适应库区消落带的周期水淹。