环境因素对气相甲苯光氧化反应机制的影响

以低压汞灯为光源,采用石英管连续流动态反应系统和特氟龙气袋静态反应系统,研究了环境因素〔RH(相对湿度)、温度、光照强度、有氧(空气)/无氧(氮气)气氛条件〕对低浓度(10~20 mg/L)气相甲苯光氧化过程的影响. 结果表明:①RH对甲苯光氧化反应影响显著. 干燥条件(RH为0%~5%)下甲苯光氧化去除率在8.3%~8.7%之间;当环境中有水蒸气存在(RH为20%)时,甲苯光氧化去除率降至6.5%~7.2%,其后光氧化去除率随着RH的进一步增加而逐渐增大,在RH为60%时达到最大值(9.4%~11.5%);但当RH继续增至80%时,去除率迅速降至4.4%~5.6%. ②甲苯光氧化去除率随着温度、光照强度的增加而提高. ③无论是干燥(RH为0%~5%)还是湿润(RH为60%)环境下,甲苯在有氧气氛下的去除率均高于无氧气氛;甲苯在有氧气氛下光氧化产物主要是苯和苯甲醛,在无氧气氛中的产物主要是苯. ④在干燥、有氧条件下,O(1D)应是甲苯光氧化的活性物种;在湿润、有氧条件下,甲苯的光氧化主要是通过·OH氧化降解;在无氧条件下,甲苯的光氧化主要是通过甲苯的直接光解完成.      

Influence of iron,nickel and cobalt on biogas production during the anaerobic fermentation of fresh residual biomass

We have investigated the dependence of the rate of the production of biogas upon the concentration of nickel, cobalt and iron at sub-toxic concentration and monitored its composition as amount of hydrogen, methane and carbon dioxide. The distribution of the added metals between the liquid and solid phase has also been monitored.

The results of our investigations show that the addition of any of the listed metals to the sludge may cause the production of a higher amount of biogas and influence the methane or carbon dioxide percentage. Conversely, the effect on the hydrogen production depends upon the metal added, the age of the active sludge used, and its adaptation to the susbtrate. As a general feature, during the acidogenesis phase, nickel reduces, while iron increases, the percentage of dihydrogen in the biogas, while cobalt has no influence.     

马缨丹对镉的生长响应及其富集、转运和亚细胞分布特点研究

镉是植物非必需且生物毒性最强的重金属元素之一,然而镉富集植物能通过一定的响应机制来减少镉对自身产生的毒害,且不同植物之间镉的解毒机制存在差异。马缨丹（Lantana camara L.）是四川汉源铅锌矿区镉污染土壤的修复植物,但是关于其镉的分布特征和解毒机制并不明确。因此本文采用盆栽模拟试验,分别设置0（对照,不添加镉）、30、90、150、210 mg·kg-1镉5个处理,研究马缨丹对镉的富集、转运及其亚细胞分布特点,探讨马缨丹对镉的耐性和解毒机制,以期为植物耐镉的生理和分子生物学机制提供一定的理论依据。结果表明：镉质量分数低于90 mg·kg-1时对马缨丹生长没有影响,而镉质量分数高于150 mg·kg-1时对马缨丹生长有显著的抑制作用;随着镉质量分数的增加,马缨丹各器官中镉的质量分数逐渐增加,表现为根＞茎＞叶,且其转运系数小于1,表明马缨丹对镉有较强的根部滞留能力,可限制过量的镉向地上部器官的转运,减少镉对地上部的毒害,这可能是马缨丹耐受镉胁迫的机制之一;随着镉质量分数的增加,马缨丹地下部和地上部的镉富集量总体上均呈增加趋势,在210 mg·kg-1镉处理时,均达到最大值,分别为142.8和1031.6μg·plant-1,不同质量分数镉处理下,马缨丹地上部的镉富集量较大,占全株镉富集量的94.0%~88.3%;镉在马缨丹根和叶细胞可溶性组分中的分配比例最高,分别占62.1%~54.2%和59.8%~52.6%,其次在细胞壁中,分别占23.8%~34.4%和28.7%~39.5%,在细胞器和细胞膜中的较低,表明可溶性组分和细胞壁是镉在马缨丹根和叶细胞中的主要分布位点,液泡区隔化和细胞壁固持可能是马缨丹对镉的重要解毒和耐性机制之一。     

Nesting biodiversity conservation into landscape management

There is universal recognition that biological diversity (biodiversity) is being lost at an alarming rate. The costs and risks of these losses for humanity are still not fully understood, but are believed to be very significant. While much is being achieved through conservation programmes, the task of addressing the current crisis remains complex, particularly as there are significant biological, social and economic challenges to nesting conservation objectives into land-use management. This paper emphasizes the socio-economic challenges, wherein a central issue is that of equitably sharing the costs and benefits of conservation among all beneficiaries, nationally and internationally. The world's biological heritage supplies mankind with a number of ecological goods and services, which have attached direct use values, indirect use values, existence values and option values. Currently, only a few direct values are tangible and here much remains to be done to capture effectively and distribute equitably the benefits arising from the other values. The paper discusses three instances where some of these challenges are being addressed, in Belize, Pakistan and Mongolia. Finally, the paper discusses the need for additional mechanisms that will help meet the challenge of establishing and maintaining conservation arrangements in the landscapes of developing countries, where much of the most threatened biota is found.     

湖泊微生物群落构建机制及研究展望

湖泊微生物生态过程研究是深入了解湖泊生态系统结构与功能的关键。论述了湖泊微生物多样性时空分布规律及群落构建机制研究进展,总结了微生物群落构建机制的分析方法,介绍了微生物生态网络构建原理及应用。群落构建机制分析方法分为统计分析法、模型推断法和生态网络分析法。统计分析法包括群落结构差异分析、群落结构-环境因子关联分析和方差分解分析等,此类方法能够初步识别驱动群落组成与结构时空差异的影响因子,判别空间因素与已知环境变量对群落构建过程的相对贡献;模型推断法包括中性群落模型方法和零模型方法等,能够进一步实现对群落构建生态过程的区分,量化和比较随机性因素及确定性因素的相对重要性;生态网络分析法可用于揭示物种共现模式,探究作为确定性因素的生物相互作用,也可用于物种-环境响应关系的研究,探究环境选择过程对群落结构的影响。     

中国城乡一体化水平的省区分异

推进形成城乡经济社会发展一体化新格局,是全面建设小康社会、实现城乡社会经济发展方式转型的重要举措。本文采用城乡发展差异系数、城乡一体化水平指数等指标,分析了中国城乡一体化水平的省区差异,揭示了这种地域分异所产生的影响因素,进一步探讨推进全国城乡一体化新格局形成的科学机制。研究表明,中国城乡发展无论是东部相对发达省区,还是西部欠发展省区,差异显著,呈现不均衡特点;城乡一体化水平受自然环境、经济社会发展综合实力和公共政策等因素影响明显;加快建构城乡一体化发展新格局,需要进一步纠正"城市偏向"的发展观,加大城乡统筹力度,推进城乡基本公共服务均等化进程,并根据变化趋势,调整公共政策的着力点,提升城乡一体化发展的区域协调性。     

Potential mechanisms of phthalate ester embryotoxicity in the abalone Haliotis diversicolor supertexta

The effects and associated toxicological mechanisms of five phthalate esters (PAEs) on abalone embryonic development were investigated by exposing the embryos to a range of PAEs concentrations (0.05, 0.2, 2 and 10 μg/mL). The results showed that PAEs could significantly reduce embryo hatchability, increase developmental malformations, and suppress the metamorphosis of abalone larvae. The possible toxicological mechanisms of PAEs to abalone embryos included, affecting the Na⁺-K⁺-pump and Ca²⁺-Mg²⁺-pump activities, altering the peroxidase (POD) level and the malondialdehyde (MDA) production, damaging the extraembryonic membranes structure, as well as disrupting endocrine-related genes (gpx, cyp3a, and 17β-hsd 12) expression properties. Taken together, this work showed that PAEs adversely affected the embryonic ontogeny of abalone. The abilities of PAEs affecting the osmoregulation, inducing oxidative stress, damaging embryo envelope structure, and causing physiological homeostasis disorder, are likely to be a part of the common mechanisms responsible for their embryonic toxicity.     

Response of non-enzymatic antioxidative mechanisms to stress caused by infection with Fusarium fungi and chemical protection in different wheat genotypes

The aim of this study was to assess the effect of infection with Fusarium fungi and chemical protection on the contents of phenolic acids and antioxidative potential of extracts from grains of 23 wheat genotypes. Based on chemical analyses including abiotic factors such as weather conditions and the location of the plantation, the authors attempted to clarify non-enzymatic antioxidative response mechanisms to two different stressors in 23 wheat genotypes. Based on chemical analysis, it was found that mass infection with fungi from the genus Fusarium induces defence mechanisms of the plant, which results in an increased production of phenolic acids, mainly those, which are substrates for the production of acids exhibiting antimicrobial action. This mechanism is confirmed by the analyses of antioxidant activity, which also increases significantly during fungal infection, connected with the production of mycotoxins. In the course of chemical plant protection, significant changes were observed in the production of phenolic acids. Even if antioxidant activity was not higher in comparison to the control, an increased production of certain phenolic acids was recorded, which suggests stimulation of the resistance system of the plant, at a simultaneous complete response of antioxidative mechanisms, as it takes place during fungal infection.     

Thermal degradation kinetics and mechanisms of Posidonia Oceanica under inert and oxidative atmospheres

The thermal degradation characteristics of Posidonia Oceanica (PO), a marine biomass abundantly available on the coastal zone of the Mediterranean Basin, were investigated using thermogravimetric analysis under inert and oxidative atmospheres. The kinetic parameters of the both thermal degradations conditions were determined using n-reaction order model. Coats–Redfern and Phadnis–Deshpande methods were used to discuss the probable degradation mechanisms. Results showed that PO is an attractive alternative for energy production owing to its elevated heating value. Moreover, PO thermal degradation follows the usual shape of biomass decomposition. Hence, under inert atmosphere, its thermal degradation had two different stages after moisture release. The first stage corresponded to the volatiles release while the second stage corresponded to the char formation. The solid-state decomposition mechanisms followed by the devolatilization step of PO were two or three dimensional diffusion controlled reaction. However, the decomposition mechanism during PO char formation corresponded to a nucleation and growth mechanism. Under oxidative atmosphere, two stages were also observed corresponding to volatiles release and char combustion, respectively. The solid-state mechanism of volatiles release followed three dimensional diffusion controlled reaction while the char combustion mechanism corresponded to a contracting area phase boundary controlled reaction.     

The use of an atmospheric dispersion model to determine influence regions in the Prince George,B.C. airshed from the burning of open wood waste piles

A means of determining air emission source regions adversely influencing the city of Prince George, British Columbia, Canada from potential burning of isolated piles of mountain pine beetle-killed lodge pole pine is presented. The analysis uses the CALPUFF atmospheric dispersion model to identify safe burning regions based on atmospheric stability and wind direction. Model results show that the location and extent of influence regions is sensitive to wind speed, wind direction, atmospheric stability and a threshold used to quantify excessive concentrations. A concentration threshold based on the Canada Wide PM_2.5 Standard is used to delineate the influence regions while Environment Canada's (EC) daily ventilation index (VI) is used to quantify local atmospheric stability. Results from the analysis, to be used by air quality meteorologists in assessing daily requests for burning permits, are presented as a series of maps delineating acceptable burning locations for sources placed at various distances from the city center and under different ventilation conditions. The results show that no burning should be allowed within 10 km of the city center; under poor ventilation conditions, no burning should be allowed within 20 km of the city center; under good ventilation conditions, burning can be allowed within 10–15 km of the city center; under good to fair ventilation conditions, burning can be allowed beyond 15 km of the city center; and if the wind direction can be reliably forecast, burning can be allowed between 5 and 10 km downwind of the city center under good ventilation conditions.