Seepage Characteristics of Rock during Damage Process

Four evolution patterns of rock permeability in damage process are summarized. And how rock pore, micro cracks and lithology form the four patterns of rock permeability evolution is analyzed. The impact of confining pressure on permeability is also presented. The permeability reduces along with the increase of confining pressure before rock failure, however, it is complex after rock failure, and it is necessary to do further research. Statistical analysis is carried out to analyze the variation range of permeability in the process of damage, which shows soft rocks vary less while hard rocks vary more. In the experiments in which the confining pressure is between 1 MPa to 40 MPa, permeability variation of 85.9% rock is within 100 times, 97% within 1000 times. Furthermore, the difference between instability of seepage and that of structure under the function of seepage is distinguished. It is proposed that the presence or absence of non-Darcy flow should be considered from the point of effective stress law.     

Phosphorus dynamics in tile-drain flow during storms in the US Midwest

Excess phosphorus (P) in freshwater systems has been associated with eutrophication in agro-ecosystems of the US Midwest and elsewhere. A better understanding of processes regulating both soluble reactive phosphorus (SRP) and total phosphorus (TP) exports to tile-drains is therefore critical to minimize P losses to streams while maintaining crop yield. This paper investigates SRP and TP dynamics at a high temporal resolution during four spring storms in two tile-drains in the US Midwest. Depending on the storm, median concentrations varied between 0.006-0.025 mg/L for SRP and 0.057-0.176 mg/L for TP. For large storms (>6 cm bulk precipitation), for which macropore flow represented between 43 and 50% of total tile-drain flow, SRP transport to tile-drains was primarily regulated by macropore flow. For smaller tile-flow generating events (<3 cm bulk precipitation), for which macropore flow only accounted for 11-17% of total tile-drain flow, SRP transport was primarily regulated by matrix flow. Total P transport to tile-drains was primarily regulated by macropore flow regardless of the storm. Soluble reactive P (0.01-1.83 mg m⁻²/storm) and TP (0.10-8.64 mg m⁻²/storm) export rates were extremely variable and positively significantly correlated to both mean discharge and bulk precipitation. Soluble reactive P accounted for 9.9-15.5% of TP fluxes for small tile-flow generating events (<3 cm bulk precipitation) and for 16.2-22.0% of TP fluxes for large precipitation events (>6 cm bulk precipitation). Although significant variations in tile-flow response to precipitation were observed, no significant differences in SRP and TP concentrations were observed between adjacent tile-drains. Results stress the dominance of particulate P and the importance of macropore flow in P transport to tile-drains in the US Midwest. Although only spring storms are investigated, this study brings critical insight into P dynamics in tile-drains at a critical time of the year for water quality management.     

超级稻两优培九生育后期的光能利用和同化产物分配

以籼、粳亚种间杂交稻两优培九及其父本93ll为材料,测定了光合速率、叶绿素荧光参数及^14CO2同化产物分配的指标。结果表明：在生育后期,与父本93ll相比,两优培九具有较高的光合能力;在中午强光的逆境条件下,原初光化学效率(Fv／Fm)、光化学猝灭系数(qP)和PSⅡ在照光下的实际光化学效率(ΦPSⅡ)的下降相对较少,具有较强的耐光抑制能力;用同位素^14C对光合同化产物运转分配进行标记研究,发现两优培九光合同化产物向穗部的分配比率较高,具有较好的源库协调性。上述有关光合和同化产物的分配特点可能是超级稻高产的生理基础。     

农用小动力机的排气对大气的污染

着重讨论了农用动力机的排气对大气的污染。在对柴油机进行全功率特性试验和自由加速试验的基础上,分析了现有农用动力机在排烟方面存在的问题,并提出今后改进措施。     

环太湖典型丘陵区不同土地利用下土壤磷素随地表径流迁移特征

在环太湖丘陵地区选择4种有代表性的土地利用类型进行野外原位试验，研究了自然降雨条件下磷素随地表径流的迁移特征。结果表明，各场降雨水相总磷的“次降雨径流平均浓度”呈对数正态分布。悬浮颗粒态磷是水相磷素迁移的主要形态，占水相总磷的76%～89%，其浓度主要由表土总磷含量及地表径流量决定;而溶解态磷（DP）主要与表土中的有效磷含量以及径流与表土相互作用深度有关。溶解态无机磷（DIP）占溶解态磷的57%～85%，竹林的DIP浓度最高。菜地径流的有机磷含量（DOP）明显高于另外3种土地利用。不同土地利用下溶解态和悬浮态磷的迁移通量分别为23～92.7mg·m^-2·a^-1和113.4～364.3mg·m^-2·a^-1，与地表径流量表现出较强的相关性。     

基于西门利克森林病毒复制子的"自杀性"DNA疫苗载体的构建及其体外表达特性

对西门利克森林病毒(SFV)复制子质粒型表达载体pSfV1进行改造，即在SFV非结构蛋白(nSPs)上游插入依赖于RNA聚合酶Ⅱ的人巨细胞病毒立即早期启动子／增强子序列(hCMV IE Pro／Enh)，同时在pS-FV1的多克隆位点下游插入SV40 poly(A)终止信号序列，获得可以完全在DNA水平上操作并具有自主复制功能的表达载体pSFV-DNA。为了进一步探讨改造载体的转染效率、表达能力以及是否能诱导细胞凋亡等特性，将报告基因EGFP插入pSFV-DNA中亚基因组启动子下游，构建的重组表达质粒pSFV-EGFP转染BHK-21细胞，转染后12h即可观察到荧光，但转染效率明显低于直接由hCMV IE Pro／Enh驱动的EGFP真核表达质粒pEGFP-C1；提取转染后48h的细胞基因组DNA，电泳发现pSFV-EGFP转染细胞均呈典型的DNA断裂(ladder)，而pEGFP-C1转染细胞未观察到这种现象。上述结果表明：改造的载体不仅可完全在DNA水平上操作，而且能正确表达外源基因和诱导细胞凋亡，为开展各种病原微生物的“自杀性”DNA疫苗研究提供了良好的工具。     

区域土壤有机氮迁移的研究进展

农田土壤氮素迁移是影响区域环境质量的重要过程。通过综述近期在区域有机氮迁移以及稳定性同位素和模型研究方法方面的进展,指出:我国有机氮源的氮素损失在人口稠密和养殖业发达的区域已经成为非点源污染的重要来源;小流域氮素输出中可溶性有机氮是一个重要组成,其输出过程受气候以及人为引起的植被、土壤及水文过程的变化的影响;稳定性氮氧同位素可以识别水体中陆源氮污染物的分布;基于GIS的过程模型可以定量分析区域氮素迁移的数量及其环境效应。进一步提出了目前需要加强农田有机氮迁移过程及其影响机制的研究,发展基于稳定性同位素的区域氮素迁移定量方法,建立稻田生态系统和水旱轮作系统的氮素迁移定量评价模型,并归纳了减少面源污染的区域氮素迁移调控措施。     

河南省砂姜黑土持水性的研究

用土壤水分能量和形态相结合的方法,对河南省几个砂姜黑土剖面的水分特征进行了研究,结论为:心土层贮水、透水能力低下是砂姜黑土容易形成内涝的主要原因;有效水不足是限制作物产量的重要因素;加深耕作深度,改善土壤的结构状况是改良砂姜黑土水分性状的根本措施。     

毒绳在辽宁省义县地区应用的初探

广泛大量地应用杀虫药物进行卫生害虫的防治,不仅耗费大量的人力财力,也造成了环境的污染,还可使害虫对杀虫药物的抗性逐年上升。为了探索如何充分地利用现有的药物,使其发挥更大的效力,提高其防治水平。节省用药量,延缓抗性的发展,减少药物对环境的污染有着重要的意义。为此本文根据实验浅谈了应用毒绳灭虫的效果。"     

不同灌溉处理下冬小麦籽粒灌浆特性的研究

2004年9月到2005年7月在河西绿洲地区结合田间试验对不同灌溉处理下冬小麦品种繁17的籽粒灌浆特性进行了研究,研究结果表明:小麦籽粒灌浆规律符合“慢-快-慢”的“S”型生长曲线,可以为一元非线性回归方程很好的模拟;水分对籽粒灌浆和粒重有较大的影响,等量不等次的灌水处理(T2、T4、T5)相比,灌水次数愈少小麦灌浆起步时间愈早,达到峰值的时间越快,全生育期只灌2水的处理(T2)达到最大灌浆速率的时间为花后第16天,而灌3水处理(T4、T5)的灌浆速率达到峰值的时间为花后第22天;等次不等量的灌溉处理(T3、T4、T5)相比,平均灌浆速率随灌溉量的增加而增大,T3灌溉量最大,其平均灌浆速率分别高于T4、T55.39%6、.02%;整个灌浆期平均灌浆速率、灌浆持续天数与产量、千粒重均呈正相关,平均灌浆速率与产量、千粒重的相关系数分别为0.704、0.721,灌浆持续天数与产量、千粒重的相关系数分别为0.568、0.615.