沉水植物龙须眼子菜(Potamogeton pectinatus)对镉、铅的吸附特性

采用龙须眼子菜(Potamogeton pectinatus)干样为实验材料,研究了龙须眼子菜对溶液中镉、铅吸附的基本特征。相同浓度不同时间条件下的吸附实验结果显示,龙须眼子菜对溶液中镉、铅离子的吸附速度很快,大约20min就能达到平衡,吸附的限速过程是小孔扩散过程,随着时间的延长,吸附的动力学特征可用假二次方程描述。相同时间不同浓度条件下的吸附实验结果显示,龙须眼子菜对镉、铅的最大吸附量分别能达到32368和24776mg·kg-1,吸附的浓度动力学特征符合Langmuir曲线方程。所有结果都表明,龙须眼子菜能有效地从溶液中去除镉和铅,可以用于水体镉、铅污染的植物修复,也可把龙须眼子菜干样作为一种新的吸附剂用于去除工业废水中的镉和铅。     

无瓣海桑和互花米草群落土壤化感作用比较

为揭示不同植物群落土壤在无瓣海桑(Sonneratia apetala)控制互花米草(Spartina alterniflora)中的作用,利用化感生物测定的方法,选用黑麦草(Lolium perenne)为受体,对比分析红树林无瓣海桑群落、互花米草群落以及无瓣海桑+互花米草群落土壤水提液的化感作用大小。结果表明3,种植物群落土壤水提液对黑麦草具有化感作用,无瓣海桑群落土壤和无瓣海桑+互花米草群落土壤水提液对黑麦草根长和苗高的影响表现出低促高抑的现象;ρ为0.25 g·mL-1的土壤水提液对黑麦草种子发芽和幼苗生长影响不大,1.0 g·mL-1土壤水提液对黑麦草根长和苗高产生显著影响,加入活性碳之后能减弱水提液的化感作用。ρ为0.25或0.5 g·mL-1条件下3,种土壤浸提液对黑麦草发芽率的影响无显著差异;ρ为1.0 g·mL-1的3种水提液都显著抑制黑麦草根长,而无瓣海桑群落土壤水提液表现出更强的化感作用,ρ为1.0 g·mL-1的土壤水提液显著抑制黑麦草苗高,无瓣海桑群落土壤对苗高的抑制作用显著强于互花米草群落土壤(P<0.01)。以黑麦草为受体,无瓣海桑群落土壤化感作用强于互花米草群落土壤,通过根系分...     

雨雪冰冻灾害后粤北森林各林型凋落物动态

为了考察中国亚热带不同森林类型对雨雪冰冻灾害的响应模式,以粤北天井山3种代表性的林型—针叶林、阔叶林和混交林为对象,于不同森林类型中比较受损森林与未受损森林在凋落物年产量、成分及月际动态方面的差异,从而在凋落物水平上反映不同森林类型在雨雪冰冻灾害后的早期恢复力。研究结果表明,灾后针叶林、阔叶林和混交林的年凋落量分别为0.52、3.21、1.37 t.hm-2,比未受损的同种森林类型年凋落量显著减少,减少程度分别为87.89%、53.46%、76.78%。由此可以看出阔叶林的植被恢复情况最好,说明在凋落物水平上,其灾后恢复的早期阶段恢复力最强。在凋落物成分方面,灾后各森林类型叶凋落物所占比例显著增加,枝凋落物所占比例则显著减少。受损针叶林和阔叶林的凋落物月动态与未受损森林基本一致,但其波动幅度较小;在混交林中,受损和未受损森林其凋落量的季节动态模式则表现出不一致性且为不规则型。根据研究结果,建议在亚热带地区优先考虑种植阔叶林以促进受损森林在类似雨雪冰冻灾害的极端天气后的恢复。     

高寒草原菌根围细菌数量对丛枝菌根真菌物种多样性的影响

基于丛枝菌根真菌(Arbuscular mycorrhizas fungi,AMF)孢子形态学鉴定,研究了藏北高寒草原主要建群植物菌根围细菌数量对AMF物种多样性的影响.结果表明:1)细菌数量1.02×106～2.96×106、3.01×106～6.06×106个/g范围内,Glomus、Acaulospora均为优势属,Scutellospora则均为最常见属;AMF孢子密度、分离频度、相对多度、重要值和种的丰度(SN、SR)均呈Glomus>Acaulospora>Scutellospora属的趋势.2)细菌数量较低时(<3.0×106个/g),AMF各属孢子密度、种的丰度(SR)相对较高,Shannon-Weiner指数、物种均匀度指数亦较高,分别达1.774和0.127.3)不同细菌数量条件下,孢子密度随细菌数量的增加而均呈微弱下降,菌根侵染率、侵染强度、丛枝丰度则均呈不同程度的提高.细菌数量>3.0×106个/g时,菌根侵染率、侵染强度和丛枝丰度随细菌数量增加而提高的趋势尤为明显.4)不同细菌数量条件下,AMF种的构成呈共有种、共有优势种较多(Glomus属均占绝对比重),特有种、稀有种较少,以及不同优势种孢子密度、相对多度和重要值差异均较悬殊的分布特征.图6表3参25     

Low-temperature CO oxidation over Au-doped 13X-type zeolite catalysts: preparation and catalytic activity

Au-supported 13X-type zeolite (Au/13X) was synthesized using a common deposition–precipitation (DP) method with a solution of sodium carbonate as a precipitate agent. Further testing was conducted to test for catalytic oxidation of CO. A study was conducted on the effects of different preparation conditions (i.e., chloroauric acid concentration, solution temperature, pH of solution, and calcinations temperature) on Au/13X for CO oxidation. In respect to the catalytic activity, the relationship between different the preparation conditions and gold particles in 13X zeolite was analyzed using X-ray diffraction, TEM and XPS. The activity of Au/13X catalysts in CO oxidation was dependent on the chloroauric acid concentration. From XRD results, a higher chloroauric acid concentration induced larger gold nanoparticles, which resulted in lower catalytic activity. Results revealed that higher temperatures induced higher Au loading, homogeneous deposit, and smaller gold clusters on the support of 13X, resulting in higher CO activity. Furthermore, a pH of 5 or 6 generated greater amounts of Au loading and smaller Au particles on 13X than at a pH of 8 or 9. This may be a result of an effective exchange between Au(OH)2Cl2- and Au(OH)₃Cl^- on specific surface sites of zeolite under the pH’s 5 and 6. The sample calcined at 300°C showed the highest activity, which may be due to the sample’s calcined at 200°C inability to decompose completely to metallic gold while the sample calcined at 400°C had larger particles of gold deposited on the support. It can be concluded from this study that Au/13X prepared from a gold solution with an initial chloroauric acid solution concentration of 1.5 × 10^-3 mol·L^-1 gold solution pH of 6, solution temperature of around 90°C, and a calcination temperature of 300°C provides optimum catalytic activity for CO oxidation.     

北京建成区道路绿化空间结构和行道树健康状况

采用实地普查测量方法,定量研究了北京建成区188条道路行道树的树种结构、径级分布、立木层次和健康状况。结果表明,国槐（Sophora japonica）、毛白杨（Populus alba）、银杏（Ginkgo biloba）是建成区主要行道树种,使用量分别占研究区树木总株数的54．7％、13．7％和7．4％。建成区树木...     

贵州浓香型白酒大曲中霉菌的18S rDNA系统发育分析

从贵州某名酒厂大曲中分离到104株丝状真菌(霉菌),通过形态特征和生理特性检测等传统鉴定方法,初步把形态和生理生化特征一致的霉菌归类为14个大类群;并采用18S rDNA序列分析,进一步把菌株归类为MJ-I至MJ-V五个类群,随后构建系统发育树.结果表明,样品中的霉菌以曲霉属(Aspergillus)为主,占总分离菌数...     

强化生物除磷系统的微生物学及生化特性研究进展

综述了强化生物除磷(Enhanced biological phosphorus removal,EBPR)系统的微生物学和生化特性两方面的最新研究进展.在微生物学方面,归纳了EBPR系统中的主要微生物——聚磷菌、聚糖菌、反硝化聚磷菌的分类及相互之间的竞争和联系.具有聚磷功能的微生物种类繁多,目前普遍认为Accumulibacter是一种典型的聚磷菌,在各种规模的EBPR系统中均不同程度的存在.关于聚磷菌和聚糖菌的联系、反硝化聚磷菌的分类问题存在争论.在生化特性方面,归纳了聚磷菌体内三大聚合物——糖原、聚β-羟基烷酸脂和聚合磷酸盐与聚磷菌代谢功能的关系.聚磷菌厌氧阶段的还原力由糖酵解和有机底物TCA循环共同提供,其比例受种群结构和实验条件影响.糖原根据不同菌株厌氧阶段的降解途径有所不同,但是对细胞都起到调节氧化平衡的作用.聚β-羟基烷酸脂的组成由有机底物决定,丙酸为底物时4种单体均可检测出来.聚磷菌厌氧释磷的能量来自聚磷分解和糖原分解,耗能受环境条件影响.图5表3参37     

Degradation of dye rhodamine B under visible irradiation with Prussian blue as a photo-Fenton reagent

Rhodamine B can be degraded using Prussian blue as a photo-Fenton like reagent under λ > 420 nm visible irradiation. Kinetic studies show ln(C _o/C _t ) is linearly proportional to the reaction time during the photo-degradation process; thus, the degradation reaction obeys a pseudo-first order kinetic law. It is very interesting that the presence of salinity such as 0.1 M KCl can speed up greatly the degradation rate: the time to achieve 90.0% degradation ratio is shortened from 120.0 to 40.0 min under comparable conditions, which is very useful in the treatment of wastewaters with high content of salinity.     

Genetic relationship between offspring and guardian adults of a rhacophorid frog and its care effort in response to paternal share

The rhacophorid frog, Kurixalus eiffingeri, is one of only a few frog species that exhibits polyandry and paternal care of eggs. Previous studies predicted that multiple paternity within an egg clutch could influence the degree of paternal care and reproductive strategies. We used microsatellite DNA markers to assess the prevalence of multiple paternity within egg clutches and the relationship between male paternal care and the percent of male’s genetic contribution to the clutch, i.e., paternal share. We conducted field observations of paternal care and collected tissues from both male frogs and tadpoles for parentage analyses. Our results showed that at least five out of 31 egg clutches had multiple paternity. Attending males were always the genetic fathers of some, if not all of the eggs in the clutch they guarded. All egg clutches except one were attended by one male frog but the attending male did not necessarily sire the majority of offspring. Multiple paternity in all cases consisted of two fathers and one mother and most likely resulted from synchronous polyandry. Paternal care effort correlated significantly with the male’s genetic contribution to the clutch, suggesting that male frogs adjust the effort expended in care in response to paternal share. In addition, our results suggest that externally fertilizing species with parental care and multiple paternity may develop novel reproductive and behavioral strategies to safeguard their parental investment and overcome sperm competition.