P对小麦Cd和As吸收与转运的影响

为了探究磷（P）对小麦幼苗镉（Cd）和砷（As）吸收转运生理机制的影响,通过水培试验,以百农207为供试材料,研究了Cd和As胁迫条件下,外源供P和缺P处理对小麦幼苗生长、根系形态、光合参数、抗氧化系统、离子含量和根茎转移系数的影响.结果表明,与缺P处理相比,外源P供应显著增加As胁迫下小麦幼苗叶绿素的含量,促进根系的生长发育,提高了生物量,而对Cd胁迫下小麦幼苗的生长影响不显著.外源P供应时显著增加了Cd胁迫条件下根系的P和Cd含量,降低了地上部的P和Cd含量;同时显著提高了As胁迫条件下地上部的P和As含量以及As向地上部的转移系数.因此,供P与否对小麦幼苗Cd和As毒害的影响表现出明显的差异性;As胁迫时,外源供P提高了As向地上部的转运能力以及根系的CAT活性,降低了As对小麦的毒害,从而促进了小麦幼苗生物量的累积;而在Cd胁迫条件下,P与Cd之间表现出一定的协同效应,外源供P在一定程度上加重了Cd对小麦的毒害效应.     

多年生植物的芽休眠及调控机理研究进展

芽休眠是一种有益的生物学特性,能够使多年生植物避开不利的环境条件,使种群在不利环境条件下得以生存.综述了多年生植物芽休眠的机制及其调控的研究进展.芽休眠是一个受多个因素和多种基因综合调控的复杂生命现象,其形成和解除受到光照、温度、水分等外界环境因素的影响和调控.在这个过程中,植物体内的激素、糖类、多胺和Ca2+等信号分子以及抗氧化酶类和能量代谢酶类等发生一系列的变化与之相适应.这些变化是在相应的基因表达调控下实现的,这些基因涉及到光、温响应基因,水分响应基因,能量代谢基因,胁迫响应基因,激素相关基因,以及MADS-box转录因子等,它们构成一个复杂的调控网络,共同控制着芽休眠的形成与解除.结合研究课题提出今后芽休眠机制的研究方向以及在农业上的应用前景.图1参67     

Test of Firefighter’s Turnout Gear in Hot and Humid Air Exposure

Five students of a rescue training school cycled at 50 W for 20 min at 20 °C before walking at 5 km/hr up to 30 min in a climatic chamber at 55 °C and 30% relative humidity. 4 different types of clothing ensembles differing in terms of thickness and thermal insulation value were tested on separate days. All subjects completed 28–30 min in light clothing, but quit after 20–27 min in 3 firefighter ensembles due to a rectal temperature of 39 °C or subjective fatigue. No difference in the evolution of mean skin or rectal temperature was seen for the 3 turnout ensembles. Sweat production amounted to about 1000 g in the turnout gears of which less than 20% evaporated. It was concluded that the small differences between the turnout gears in terms of design, thickness and insulation value had no effect on the resulting heat physiological strain for the given experimental conditions.     

Physiological mechanisms of degradation of fish populations in acidified water bodies

Disturbances in fish that result from water acidification and related factors are analyzed in the context of generalizations based on the results of experimental and field studies. It is shown that low pH, monomeric aluminum, and other metal ions have an adverse effect on physiological processes in fish and are a major cause of their death in acidified lakes and rivers. The vulnerability of fish to low water pH at different stages of their life cycle and mechanisms of delayed mortality are discussed.     

Monitoring toxics by group testing

Monitoring the environment for a large list of organic compounds present at low levels is costly. The primary purpose of such monitoring is to assure that hazardous levels of such compounds are not released into, or present in, the environment. Viewing this as a quality control problem, we suggest that samples from different sources can be composited using group testing procedures prior to analysis. Our purpose is to describe the basic concepts and suggest problems requiring study.     

互花米草对持续淹水胁迫的生理响应

对互花米草进行了40cm水深的持续淹水胁迫,研究了其生理指标的响应.结果显示,淹水胁迫下,互花米草叶片中可溶性糖含量和叶绿索含量在初期均显著低于对照,随后逐渐积累并高于对照.丙二醛含量在初期显著高于对照,随后与对照组的差异逐渐减小,至生长季末与对照水平相当.过氧化物酶活性在淹水后63d内均高于对照,至生长季末则低于对照,而超氧化物歧化酶活性则始终高于对照.至生长季末,持续淹水胁迫条件下的互花米草生物量低于对照,其形态学上表现为植株矮小、根系变短、节长变短、地下部分所占生物量比重降低.研究结果表明,持续淹水胁迫对互花米草的生理指标产生影响,但互花米草可以通过生理和形态学的响应来适应这种胁迫,因此,必须进一步结合其它物理控制措施进行综合治理.     

梭鱼草净化黑臭河水的日变化试验研究

测定了曝气和非曝气的2个植物净化槽在1 d中7个不同时间点的出水水质理化指标(pH、DO、COD、NH_4~+-N、TP)及植物叶片的叶绿素(Chla)、可溶性蛋白(SP)含量及过氧化物酶(POD)活性,另设空白槽为对照;试验目的是研究各指标的日变化情况及相互关系,为提高梭鱼草净化黑臭河水的处理效率及其植物净化槽的合理优化运行提供科学依据.结果表明,各水槽内所测指标的变化均在一定程度上与光强变化相关,对非曝气植物槽的分析发现,在出水理化指标中TP浓度与光强的相关性最好(r=0.93,p<0.01),而在植物生理指标中SP含量与光强相关性最好(r=0.91,p<0.01);植物处理使出水的DO日均值增加了0.13 mg/L,而曝气植物处理则使其增加了1.8 mg/L,曝气是对城市黑臭河水进行植物净化修复的必要辅助手段;曝气植物槽对黑臭河水中COD和NH_4~+-N的去除率日均值比植物槽升高了7.1%和6.3%(p<0.01),TP去除率却相应下降了38%(p<0.01);与非曝气槽植物相比,曝气槽植物体内Chla、SP日平均含量显著降低(p<0.05)而POD活性显著升高(p<0.05);光强和曝气的变化能迅速而显著地影响梭鱼草的生理特性从而改善其净化槽出水水质,是构建和优化黑臭河水植物净化槽时值得考虑的重要调控因素.     

五大连池水体氮和磷代谢相关的微生物类群分异特性

为阐明东北典型湖库水体中与氮和磷代谢相关的微生物类群的时空分布及其与主要水质指标的相互关系,以五大连池为重点研究对象,调查水体中4种细菌生理类群——AB(氨化细菌)、DNB(反硝化细菌)、OPB(有机磷分解菌)和IPB(无机磷溶解菌)的分布特征.结果表明:4种细菌生理类群数量季节变化规律明显,其中AB,OPB和IPB均在夏季达到峰值,平均值分别为2.8×105,1.1×104和1.6×104 CFU/mL,而DNB的数量则是在秋季相对较高,平均值为1.3×103 mL-1;同时不同点位之间微生物类群的分布也存在一定的差异性.微生物类群与相关水质指标之间的统计分析表明,水体中AB的数量与ρ(TN)和ρ(NH3-N)密切相关,相关系数(r)分别为0.813(P<0.05)和0.933(P<0.01);OPB和IPB的数量与ρ(TP)呈显著正相关;相比ρ(NO3--N)而言,DNB与ρ(NO2--N)之间的相关性更为明显(r=0.846,P<0.05).      

萘胁迫对金鱼藻生理特性的影响

为探讨NAP(萘)对金鱼藻的毒性及其机理,采用1/10Hoagland营养液水培法,研究了ρ(NAP)分别为1.25、2.5、5、10、20和40mg/L下金鱼藻中w(叶绿素)、w(可溶性蛋白)、w(GSH)(GSH为还原型谷胱甘肽)、MDA(丙二醛)含量及SOD(超氧化物歧化酶)和POD(过氧化物酶)活性的变化. 结果表明,在ρ(NAP)为1.25和2.5mg/L时,金鱼藻的各项生理活动与对照组基本没有显著差异(P>0.05). ρ(NAP)越高,对金鱼藻的毒性越大,当ρ(NAP)达40mg/L时,金鱼藻的生理活动受到显著影响(P<0.05). 在胁迫后期(第5、7天),随着ρ(NAP)的增加,w(叶绿素)、w(可溶性蛋白)以及SOD活性均有不同程度的下降,同时w(GSH)和MDA含量上升,膜脂过氧化加剧. 说明w(叶绿素)、MDA含量和SOD活性等是金鱼藻对萘胁迫较为敏感的参数,能表征萘胁迫的毒性.      

Measuring the effectiveness of San Francisco’s planning standard for pedestrian wind comfort

ABSTRACT

In 1985, San Francisco adopted a wind comfort standard in its Downtown Area Plan in response to increasing concerns about the city’s downtown public open spaces becoming excessively windy. After 30 years of implementation, this study revisits the standard and examines its effectiveness in promoting pedestrian comfort. Seven hundred one valid samples were collected from 6 months of field study, which combined surveying pedestrians and on-site collection of microclimate data. Statistical analysis and an assessment using the physiological equivalent temperature show that 11 mph (4.92 m/s), the comfort criterion in places for walking, performs as an effective determinant of outdoor comfort in San Francisco. This study sheds light on climate-resilience of cities, as they have become key urban challenges today.