隧道施工地质灾害分析与防治对策

根据隧道施工地质灾害成因与特性,对隧道施工地质灾害进行分类,并对其特点进行分析,提出隧道施工地质灾害防治原则。在建立隧道施工地质灾害监测与预警系统的基础上,对常见灾害中的塌方、涌水、突泥、瓦斯爆炸、岩爆等现象提出防治措施,旨在为隧道安全施工提供参考。     

人工湿地对二级出水中TN、TP去除效果的季节性研究

研究了垂直流和表面流两种人工湿地系统在水力停留时间为2 d条件下,在不同季节对二级出水中TN、TP的去除效果。结果显示,垂直流湿地系统对TN、TP的去除效果优于表面流湿地系统。两种类型的人工湿地对TN的去除效果随季节的变化而波动,夏秋季节去除率最高,春季次之,冬季去除效果最差;垂直流人工湿地系统对TP的去除效果随季节的变化趋势与TN去除率的变化相同,而表面流湿地系统对TP的去除效果在春夏秋季变化不大,冬季的平均去除率仅有16.5%。分析认为,人工湿地应用于二级出水的深度处理,对于满足观赏性景观环境用水(尤其是观赏性河道和湖泊类)的水质指标是可行的。     

高效率颗粒物微物理模型简介与重污染过程应用分析

中国细颗粒物(PM2.5)导致的空气污染和雾霾天气问题越来越突出,在低层对流层中很多地方都有显著的二次颗粒物生成过程,因此对颗粒物物理化学转化过程的研究具有重要意义,其转化过程对空气质量模式模拟和预报的准确性有重要影响。高效率颗粒物微物理(APM)模型经过近20多年的研究和发展,在全球化学传输模型(GEOS-Chem)、区域性气象和化学预报模型(WRF-Chem)通用地球系统模型(CESM-CAM5)等气象及环境空气质量预报模型中取得了很好的应用验证,能够在全球/区域等不同尺度对粒子生成、长大、凝聚、消除等微物理过程以及气溶胶光学厚度(AOD)、直接/间接辐射强迫等进行模拟。应用GEOS-Chem-APM模式模拟了2014年2月京津冀区域的重污染过程。结果显示,湿度模拟的准确性对其他物理和污染物浓度等模拟结果有重要作用;2月20—26日的重污染过程模拟结果与实际观测较为吻合,主要污染特点是较高的湿度(90%以上),同时,二次颗粒物和包裹了二次物种的一次颗粒物(黑碳/有机碳)是低能见度的最大贡献者。     

珠三角地区大气PM_(2.5)理化特性季节规律与成因

基于珠三角大气超级站2013年8月至2014年3月PM2.5、PM2.5中主要水溶性无机离子组分及其重要气态前体物等参数的逐时在线监测结果,揭示当地大气PM2.5中二次无机组分与其气态前体物的相互作用,以及PM2.5理化特性与成因的季节差异。结果表明,观测期间,PM2.5、PM10的年平均质量浓度分别为64.2、105.1μg/m3,PM2.5在PM10中所占比例(PM2.5/PM10)平均为61.1%。SO2-4、NO-3、NH+4的年平均质量浓度分别为16.6、9.0、10.2μg/m3,3者之和(SNA)占PM2.5的比例(SNA/PM2.5)平均为55.8%,体现了二次转化对珠三角地区PM2.5污染的重要影响;不同季节,SNA/PM2.5为46.0%~64.3%,夏季最低,冬季最高,其中SO2-4、NH+4对PM2.5的贡献相对稳定,NO-3贡献的季节差异较大;秋、冬季各项观测参数浓度的日变化规律相对明显,夏季除HNO3和NH3外,多项观测参数在低浓度水平波动,日变化规律不明显;珠三角大气中具有足量气态NH3以中和硫酸盐和硝酸盐,PM2.5中NH+4、SO2-4、NO-3主要以(NH4)2SO4和NH4NO3形式存在;本研究站点夏季的硫氧化率和氮氧化率均高于广州市,这充分体现了该站点的区域性特征。     

Dynamics of soil organic matter in primary and secondary forest succession on sandy soils in The Netherlands: An application of the ROMUL model

We applied the simulation model ROMUL of soil organic matter dynamics in order to analyse and predict forest soil organic matter (SOM) changes following stand growth and also to identify gaps of data and modelling problems. SOM build-up was analysed (a) from bare sand to forest soil during a primary succession in Scots pine forest and (b) on mature forest soil under Douglas fir plantations as an example of secondary succession in The Netherlands. As some of the experimental data were unreliable we compiled a set of various scenarios with different soil moisture regime, initial SOM pools and amount and quality of above and below ground litter input. This allowed us to find the scenarios that reflect the SOM dynamics more realistically. In the Scots pine forest, total litter input was estimated as 0.50 kg m⁻² year⁻¹. Two scenarios were defined for the test runs: (a) forest floor moisture regimes—‘dry, mesic and hydric’ and (b) augmenting a root litter pool with three ratios of needles and branches to roots: 1:1, 1:1.5 and 1:2.0. The scenario finally compiled had the following characteristics: (a) climate for dry site with summer drought and high winter moisture of forest floor; (b) a litter input of 0.25 kg m⁻² year⁻¹ above ground and 0.50 kg m⁻² year⁻¹ below ground; (c) a low nitrogen and ash content in all litter fall fractions. The test runs for the estimation of the initial SOM pools and the amount and proportion of above and below ground litter fall were also performed in the Douglas fir plantation. The inputs of above ground litter tested in various combinations were 0.30 and 0.60 kg m⁻² year⁻¹, and below ground litter 0.30, 0.60 and 0.90 kg m⁻² year⁻¹. The scenario that fitted the experimental data had an SOM pool of 20–25 kg m⁻², an aboveground litter input of 0.6 kg m⁻² year⁻¹and a below ground litter input of 0.9 kg m⁻² year⁻¹. The long-term simulation corresponded well with the observed patterns of soil organic matter accumulation associated with the forest soil development in primary and secondary succession. During primary succession in Scots pine forest on dry sand there is a consistent accumulation of a raw humus forest floor. The soil dynamics in the Douglas fir plantation also coincide with the observed patterns of SOM changes during the secondary succession, with SOM decreasing significantly under young forest, and SOM being restored in the older stands.     

Sequestration of pyrrolizidine alkaloids by larvae ofTellervo zoilus (Lepidoptera: Ithomiinae) and their role in the chemical protection of adults against the spiderNephila maculata (Araneidae)

Summary Life stages of the primitive Australian ithomiine butterflyTellervo zoilus and its larval hostplant, the apocynaceous vineParsonsia straminea, were quantitatively assayed for pyrrolizidine alkaloids (PAs). PAs were found in all stages, mainly as N-oxides, being most concentrated in larvae and freshly-emerged adults. Although adults feed at various confirmed PA sources this probably does not compensate for losses, as wild-caught adults had considerably lower concentrations of PAs. The main alkaloid present in both freshly-emerged adults and in leaves of the host-plant was lycopsamine (1b), stored by butterflies in the N-oxide form. Its presence in higher proportion, in relation to intermedine (1a), in larvae, pupae and adults ofTellervo in relation to the host-plants suggests the inversion of intermedine to lycopsamine by the insects. No 14-member ring macrocyclic PAs were detected in either food-plant or butterflies. Several other PAs were found in wild-caught adults reflecting visits to other PA sources. PAs were also found in high concentrations in freshly-emerged individuals of the danaineEuploea core bred onParsonsia straminea. Wild-caughtDanaus affinis had high PA levels acquired from adult feeding. Freshly emergedEuploea raised onIschnocarpus frutescens andDanaus raised onIschnostemma carnosum (both PA-free) were preyed on by the orb weaving spiderNephila maculata, and showed no PAs. In all cases where PAs were present, most butterflies were liberated, usually cut out of the web unharmed, byNephila. The spider's response was not closely linked to PA concentration, however, and may also depend on hunger levels and previous experience with PA-containing butterflies. All control and other non-PA containing butterflies were consumed although rejection of some body parts of freshly-emergedDanaus affinis suggests that compounds other than PAs may be involved.     

Secondary metabolism — evolution and function: Products or processes?

Summary The distinguishing characteristics of secondary metabolism and its associated metabolites are outlined. Current theories relating to the function of secondary metabolism in plants and micro-organisms are enumerated and the view that consideration of the processes rather than the products may best explain the origins of secondary metabolism is discussed.     

中亚热带丝栗栲次生林群落高度级结构分析

以高度级为参考坐标，应用衡量优势种群及群落结构动态的失稳率、群落垂直空间的分享度、α—多样性及群落高度级梯度β—多样性等指标对中亚热带丝栗栲次生林群落高度级结构特征及其动态进行分析评价。结果表明：丝栗栲群落及其优势种群个体数、群落物种数和种对级的分享度随高度级增加都呈下降趋势；各高度级物种数和个体数呈明显的正相关关系；级间失稳率显示，群落在第2、3、6、7高度级呈增长趋势，第4、5高度级呈衰退趋势，群落整体具有增长性结构；群落随高度级形成丰富度指数(dMa)、Shannon—Wiener指数(H)逐渐降低，均匀度指数(J)先增后减的变化趋势；随高度级梯度的增加，群落相邻高度级间Whittaker指数(βw)呈上升趋势，而Mofisita—Horn指数(CMH)呈不规则地跳跃式变化，表现了共有种在群落不同高度级的数量差异。图3表2参15。     

How do slugs cope with toxic alkaloids?

Summary. Arion lusitanicus and other slugs are able to feed on a variety of plants, even those containing toxic secondary metabolites, such as alkaloids. Alkaloids, like sparteine, lupanine, quinidine and atropine are avoided in no-choice feeding experiments only when they are present in concentrations above 1 mg/g food pellet. Alkaloids (sparteine, lupanine, cytisine, quinidine, atropine, senecionine, eserine, and harmaline) are toxic to Arion lusitanicus when injected. LD₅₀ values are 10 to 20 fold higher than in vertebrates indicating that slugs have a high tolerance towards food toxins. The tolerance is higher in young animals than in adult slugs. Injected alkaloids are rapidly detoxified within 72 h. Tolerance and detoxification can be induced by feeding slugs on non-lethal doses of lupin alkaloids. Using isolated microsomal preparations from the digestive gland, active detoxification was observed in vitro. Evidence is presented that cytochrome p450 plays an important role in detoxification of the applied alkaloids. A powerful and inducible detoxification systems appears to be the main mechanism that allows slugs to feed on plants rich in secondary metabolites (when no other food is available), that are usually avoided by other herbivores.     

Recovery of Faunal Communities During Tropical Forest Regeneration

Abstract:  As mature tropical forests are cleared, secondary forests may play an important role in the conservation of animal species, depending on how fast animal communities recover during forest regeneration. I reviewed published studies on the recovery of animal species richness and composition during tropical forest regeneration. In 38 of the 39 data sets I examined, conversion of forest to agriculture or pasture substantially reduced species richness. Given suitable conditions for forest recovery, the species richness of the animal taxa considered can be predicted to resemble that of mature forests roughly 20–40 years after land abandonment. At least for ants and birds, however, recovery of species composition appears to take substantially longer than recovery of species richness. Because species richness for many taxa appears to recover relatively rapidly in secondary forests, conservation of secondary forests may be an effective investment in future diversity. The slower recovery of species composition indicates, however, that some species will require stands of mature forest to persist.