额济纳天然胡杨林水分利用效率动态变化研究

黑河下游的额济纳绿洲是我国西北地区重要的生态屏障,也是当地人民赖以生存的自然资源,然而由于种种原因,这片绿洲正在衰败并且有消亡的危险.胡杨是典型的潜水旱中生植物,它虽然有较强的耐大气干旱、耐盐碱能力,其生长发育与水分条件的优劣有着十分密切的关系.本文通过研究额济纳天然胡杨的叶水势、蒸腾速率、光合速率的变化规律,综合分析其水分利用效率与叶水势的相关关系,了解胡杨树体内水分运移关系,为揭示胡杨生存现状和合理利用水资源提供理论依据,为合理保护额济纳绿洲胡杨林提供科学支持.     

Identification and ranking of the risky organic contaminants in the source water of the Danjiangkou reservoir

The Danjiangkou reservoir was selected to provide the source water for the middle routes of the South to North Water Transfer Project, which has provoked many environmental concerns. To date, investigations of water contamination of the source water of the Danjiangkou reservoir with organic micro-pollutants have been limited. This study was conducted to identify and rank organic contaminants that pose risks in the Danjiangkou reservoir. To this end, the Chemical Hazard Evaluation and Manage- ment Strategies （CHEMS-1） approach was adapted to integrate the deconvolution technology of qualitative identifying contaminants for site-specific environmental matrices. The samples were screened for the presence of 1093 contaminants using deconvolution technologies and the hazard values of the identified contaminants were calculated using the adapted CHEMS-1 approach accord- ing to their hazardous properties and occurrence in source water. The results showed that 46 contaminants from 1093 targets were present in Danjiangkou water, 23 of which appeared at frequencies higher than 50%, and 15 of which were identified as priorities. Over half （53%） of the high- ranked contaminants were polycyclic aromatic hydrocar- bons （PAHs）, with chrysene ranked highest on the list. Health risk assessment of the top-ranked PAHs was conducted and revealed that cancer risks of PAHs detected in the source water of Danjiangkou to different populations ranged from 10-7 to 104, indicating a low cancer risk to consumers. The results of this study indicated that the adapted CHEMS-1 approach was feasible for site-specific screening of organic contaminants to identify and rank potential priority pollutants.     

The hormetic effect of cadmium on the activity of antioxidant enzymes in the earthworm Eisenia fetida

The hormetic dose–response relationships induced by environmental toxic agents are often characterized by low-dose stimulation and high-dose inhibition. Confirmation of the general phenomenon of hormesis may have significant implications for ecological risk assessment, although the mechanisms that underlie hormesis remain an enigma. In this study, a model-based approach for describing a dose–response relationship incorporating the hormetic effect was applied to the detection and estimation of the hormetic effect of cadmium (Cd) on the activity of antioxidant enzymes in the earthworm Eisenia fetida. The results showed that Cd at low concentrations induced an increase in the activity of catalase and superoxide dismutase (SOD), but high concentrations inhibited the enzymes, and this was reflected in an inverted U-shaped curve. The maximum hormetic magnitude of SOD activity was higher than that of catalase. The presence of hormesis induced by cadmium in the earthworm may be related to activation of adaptive pathways.     

Relationships between volatile organic compounds with an emphasis on terpene compounds and genetic matrix in inoculated and non-inoculated winter wheat cultivars

In the present study, we focus on the analysis of the volatile organic compound (VOC) contents in the grain of a representative set of winter wheat cultivars grown in Central Europe. The cultivars were grown in control conditions or were inoculated with the fungus Fusarium culmorum. In the analysed samples, hydrocarbons, alcohols, aldehydes and ketones, aromatics, terpenes and others were found. Among them, results for terpenes seem particularly important. The discriminant analysis allowed complete separation of the quality groups of wheat based on VOCs. Simultaneously, a genetic matrix was created based on the genetic distance between the wheat cultivars and the Mantel test was used to compare it with the VOC matrix. The analysis revealed relationships between the genetic matrix and the overall VOCs, as well as terpenes. The obtained results indicate a significant relationship between microorganisms that exist in the environment, genetic features of plants and VOCs formed in the grain.     

淹没旋转射流的理论分析及力学模型

综述了淹没条件下旋转射流的基本特点、有关理论以及根据边界层流动的力学分析方法得出的淹没自由旋转射流和井筒空间的旋转射流的力学近似分析模型及其解析解,从而为全面深入地研究旋转射流的流动机理,指导该机理在石油工程中的应用,提供了理论基础。     

城市边缘区土地利用变化及人文驱动力机制研究

利用多期遥感影像 ,对土地利用进行了测量。再运用GIS软件进行空间叠加求得研究区土地利用变化的转移矩阵 ,分析马山区11年来土地利用变化的空间过程。结果表明 :1988～1998年之间农业景观为主的农田、林地显著减少 ,城镇沿公路迅速向外扩张 ,旅游度假区沿湖岸不断扩大且呈集中化趋势。这一变化趋势的驱动力是旅游为主的第三产业迅速发展、外资大量涌入、城镇人口增长和农副产品的价格波动。     

毒死蜱和吡虫啉对意大利工蜂(Apis mellifera L.)的慢性经口毒性

文章以毒死蜱和吡虫啉为受试农药,以4日龄内的意大利工蜂(Apis melifera L.)为受试生物,研究2种农药对意大利工蜂的10 d经口慢性毒性。结果显示:参比物质乐果对意大利工蜂的10 d半致死浓度(10 d-LC50)为0.550μg a.i.·g~(-1)食物,平均每天半致死剂量(LDD50)为0.019μg a.i.·蜂~(-1)·天~(-1);在有效试验条件下,毒死蜱对意大利工蜂的10 d LC50为0.582μg a.i.·g~(-1)食物,LDD50为0.021μg a.i.·蜂~(-1)·天~(-1);吡虫啉对意大利工蜂的10 d LC50为0.055μg a.i.·g~(-1)食物,LDD50为1.542 ng a.i.·蜂~(-1)·天~(-1)。试验结果可为毒死蜱和吡虫啉的安全使用提供科学参考,同时可促进我国农药对蜜蜂的安全性评价体系的完善。     

动剪切模量与阻尼比的共振柱和动三轴对比试验研究∗

利用 GCTS 共振柱试验仪和循环三轴试验仪分别对砂土和黏土进行了动剪切模量和阻尼比试验,研究了共振柱和动三轴试验得到的规准化动剪切模量比 G/G_max和阻尼比 λ 随剪应变 γ 变化的规律,并考虑了土样类别以及深度对两种方法测得的 G/G_max和 λ 的影响。试验结果表明,共振柱和动三轴两种试验得到的土体 G/G_max和 λ 具有良好的一致性,且与土样的深度和类别无关,可将两种试验方法结合起来共同测定土体 10^-6~10^-2 应变范围内的 G/G_max和 λ,从而为重大工程场地地震效应分析提供宽应变范围内的 G/Gmax和 λ 曲线。     

土地资源、环境与经济发展的协调性评价

评价系统发展协调性的“协调判别法”是这样一种方法：先为系统的各子系统选择一些有代表性又可用一定指标度量的要素,按一定标准将要素分作满意与不满意两类,统计加总各类要素的数量,以之作为度量用的综合指标,并经归一化处理得各子系统的“状态数”;再将这些子系统与一定的“状态空间”对应,在此空间中利用“状态数”确定子系统所属系统的“状态点”及“完全协调线”;然后分别计算状态点与协调线的距离（偏离度）、状态点与原点的距离（优化度）,借助它们便可评价各子系统发展的同步性及相应系统的协调性。以此方法对通州市由土地利用、自然环境和社会经济3个子系统组成的系统进行的协调性评价表明,“协调判别法”具有含义明确、简单、较客观、易操作、可比性强的特点,适用于评价复杂系统的协调发展问题。     

Enhanced antioxidant capacity and upregulated transporter genes contribute to the UV-B-induced increase in blinin in Conyza blinii

Environmental Science and Pollution Research - Conyza blinii (C. blinii) is a traditional Chinese medicinal plant mainly grown in Sichuan, China. C. blinii is suitable for studying the mechanism of...