干旱胁迫和复水对梨幼树生理特性的影响

为了解植物干旱生理适应机制和恢复机制,以梨品种‘翠冠’和‘黄冠’幼树为试材,研究土壤干旱胁迫及复水条件下叶片光合参数、叶片相对含水量、叶片质膜透性、超氧化物歧化酶活性及脯氨酸含量的变化特性.结果显示:1)随着干旱胁迫的加剧,两品种的叶片净光合速率、气孔导度和蒸腾速率均呈下降趋势;‘翠冠’叶片胞间CO2浓度呈先降后升的趋势,而‘黄冠’呈持续下降趋势,但‘黄冠’光合作用的4项指标明显高于‘翠冠’;复水后,两品种的光合指标恢复显著,但均未超过对照水平.2)干旱胁迫引起两品种的叶片相对含水量急剧下降,叶片质膜透性和脯氨酸含量显著升高,超氧化物歧化酶活性呈先升后降趋势;复水后,两品种的4项指标不同程度地得以恢复,但大部分指标没有恢复到对照水平,其中‘黄冠’各项指标在复水前后的变化幅度比‘翠冠’更小.综合分析表明,‘翠冠’和‘黄冠’对干旱胁迫的响应存在差异,‘黄冠’对干旱逆境具有更强的适应能力.     

低渗非达西多相渗流的数值模拟分析

从低渗介质渗透率与压力梯度的关系出发建立数值模型,修正已有数值模拟器的渗透率项进行功能扩展,并给出计算实例.结果表明,在其他条件相同情况下,启动压力梯度越大,相同时间内的累积采油量、累积注水量越小,反之越大.启动压力梯度越大,渗流规律越偏离达西定律.本文建立的模型比传统模型更能准确反映低渗介质中的渗流特征.     

袋式除尘器在线清灰流场分布的研究

采用流体动力学CFD软件Fluent,通过调节滤袋渗透率和粉尘厚度模拟清灰前后表面粉尘负荷的差异性,对袋式除尘器在线清灰条件下的流场进行数值模拟分析,给出不同清灰条件下花板平面气流速度分布图,得出滤袋清灰前由于表面粉尘负荷的影响,气流分布比较均匀;清灰时,被清灰滤袋透气性的增强,过滤风速明显提高,其瞬间气流冲击是造成滤袋破损的主要原因。将模拟结果与实际工程运行情况进行对比,分析了其可靠性,为袋式除尘器的改进和设计提供了理论参考。     

碱水残渣等工业“三废”调剖可行性研究

从加大中原油田调剖措施工作力度的必要性、紧迫性出发。通过利用室内实验前后岩心渗透率、铸体图象、压汞参数、扫描电镜孔隙变化等实验分析结果,研究了利用碱水残渣、废纸浆、锯木灰等工业“三废”调剖的可行性,及其在中原油田水井调剖中的适用性。结合目前注水冲刷地层孔隙结构变化的特点,还提出配套改进办法和扩大推广应用规模的建议。     

铬、镉、铅胁迫对青菜叶片几种生理生化指标的影响

研究了溶液培养条件下铬、镉、铅胁迫对青菜叶片细胞膜透性、叶绿素含量和游离脯氨酸含量等的影响,结果表明：随着Ｃｒ＾６＋,Ｃｄ＾２＋,Ｐｂ＾２＋处理时间的延长和处理浓度的增加,青菜叶片细胞膜透性显著增大,叶绿素ａ／ｂ值逐渐降低,游离脯氨酸含量明显增加,其中游离脯氨酸含量增加的时间比细胞膜透性增大明显超前,而叶绿素ａ／ｂ植降低的时间在这３种重金属中未见明显的规律性。     

鼠李糖脂强化多环芳烃微生物修复的研究进展

多环芳烃（PAHs）是普遍存在于环境中具有强烈毒性、致突变性和致癌性的难降解有机物,可造成严重的环境污染。由于低水溶性而导致的低生物可利用率是限制PAHs微生物降解的主要因素。生物表面活性剂鼠李糖脂由于在形成胶束后能够大幅提高PAHs的表观溶解度,且毒性低、无二次污染,因而在PAHs微生物降解的研究中得到广泛关注。目前关于鼠李糖脂强化PAHs微生物降解的研究主要集中于其强化效果,而对其强化机制的研究仍不够深入。该文基于鼠李糖脂的性质及铜绿假单胞菌（Pseudomonas aeruginosa）的鼠李糖脂生物合成及调控,从鼠李糖脂提高PAHs溶解度、强化胶束传质、提高细胞表面疏水性、降低细胞表面Zeta电位、提高细胞膜通透性等方面综述其在强化PAHs微生物降解机制方面的最新研究进展,并总结了温度、pH、浓度和离子强度等环境因素对强化效果的影响。在此基础上,提出未来需要进一步探索鼠李糖脂生物可降解性与强化降解效果之间的平衡关系,明确pH影响PAHs溶解度的机理,并从基因、转录、蛋白和代谢水平对鼠李糖脂作用前后降解菌内参与调控菌体细胞表面疏水性（CSH）和膜通透性的相关基因的表达差异进行分析...     

SENSITIVITY OF GROUNDWATER FLOW MODELS TO VERTICAL VARIABILITY OF AQUIFER CONSTANTS1

ABSTRACT: The Ogallala aquifer in the Oklahoma Panhandle is in need of better management because of increased groundwater demand which has caused declines in static water levels at an alarming rate. A groundwater management computer model was developed for the Ogallala aquifer in the Texas Panhandle and treats the aquifer as a homogeneous system. In this study, the computer model has been modified in order to evaluate the effects of vertical layering on semi-static water level changes which occur during the dewatering of a single unconfined aquifer. The modified model was applied to a study area near Guymon, Oklahoma, using both the homogeneous and the multilayered cases. The aquifer is characterized by a saturated thickness of 400 feet. The accumulated drawdown values of the homogeneous and the multilayered cases demonstrate that an average difference of approximately 22% of the original saturated thickness occurs between the two cases before the base of the aquifer is encountered. Approximately 25% more time is required to dewater the layered aquifer. Thus, vertical variations of lithology in an aquifer such as the Ogallala should be considered when prediction is made relative to groundwater management.     

基于GA-BP的渗透系数多目标反演分析模型研究

针对渗透系数反演结果不唯一问题,以扬压力和渗流量2类渗流监测效应量为反演目标,建立了基于正交设计、有限元正分析和GA-BP相结合的渗透系数多目标反演分析模型。结合水口大坝2009—2018年渗流监测时间序列数据,开展了大坝坝体、坝基岩体渗透系数反演研究,并对反演结果进行了验证。研究结果表明:建立的渗透系数反演模型可较好地解决渗流单目标反演的缺陷,反演结果为绝对渗透系数,且反演结果真实可靠。     

四环素类抗生素对淡水绿藻的毒性作用

四环素类抗生素是目前世界上应用最为广泛的抗生素之一,也是我国畜禽养殖业中使用量最大的兽药和饲料添加剂.由于该类物质不易被生物体吸收且当前的污水处理设施对抗生素不能彻底去除,故大量抗生素及其代谢产物最终进入地表水环境,其对水生态系统和人体健康的潜在威胁值得关注.本研究以水生态系统初级生产者淡水绿藻为受试生物,系统考察四环素、金霉素和强力霉素对蛋白核小球藻、斜生栅藻细胞膜通透性和生长抑制作用的影响.结果表明,抗生素暴露96 h后,强力霉素在整个作用浓度范围内使供试淡水绿藻细胞膜通透性降低;而金霉素和四环素低浓度暴露可以增大藻细胞膜通透性,此后随着作用浓度的增大转为降低.3种抗生素对淡水绿藻生长抑制率大致呈现强力霉素>四环素>金霉素的顺序趋势.斜生栅藻对四环素类抗生素的毒性响应较蛋白核小球藻更为敏感.     

Estimation of primary drainage three-phase relative permeability for organic liquid transport in the vadose zone

The modeling of transport of organic liquid contaminants through the vadose zone often requires three-phase relative permeabilities. Since these are difficult to measure, predictive models are usually used. The objective of this study is to assess the ability of eight common models to predict the drainage relative permeability to oil in a three-phase system (water-oil-air). A comparison of the models' estimates using data set from Oak [Oak, M.J., 1990. Three-phase relative permeability of water-wet Berea. In: Seventh Symposium on Enhanced Oil Recovery, Paper SPE/Doe 20183. Tulsa, OK, April 22-25] showed that they provide very different predictions for the same system. The goodness of the models does not increase with the amount of data or computation that the models require. Also, the calculations showed how different interpretations of the models and of the terminology associated with them can significantly impact the predictions. Thus, considerable error may be introduced into the simulations of organic liquid transport in the vadose zone depending on the selection and interpretation of the three-phase relative permeability model.