Food source and feeding habit of Helice tientsinensis from the common reed vegetation in high marsh of Yellow River Delta,China

Investigating the composition of food sources with stable isotope method can provide direct evidence for the top-down control in the coastal wetland.In this study,we examined food source and feeding habit of Helice tientsinensis of common reed (Phragmites australis) vegetation in high marsh of Yellow River Delta.The results showed that the density of crab was (5.5 1.5) ind&middot;m~(-2),with the behavior of climbing P.australis to feed on the leaves at night.Under the same indoor experimental condition,H.tientsinensis showed feeding preference on fresh leaves of P.australis.The stable isotope food source analysis showed that the leaves of P.australis were one of the important food sources of H.tientsinensis in the field.There were temporal variations in the proportion of fresh leaves [May:(6.44.9) %,July:(5.84.9) %,September:(12.58.8) %] and dead leaves [May:(12.47.8) %,July:(15.59.9) %,September:(15.19.4) %].Therefore,H.tientsinensis could inhibit P.australis&#39;s growth and affect litter decomposition through feeding disturbance behavior.</p

基于景观格局的新疆生态脆弱性综合评价研究

以新疆土地资源为研究对象,选取分维倒数、破碎度两个景观格局指数以及沙漠化敏感性、盐渍化敏感性和土壤侵蚀敏感性3个生态系统敏感性指数构建景观类型脆弱度和区域生态脆弱度模型,利用连续覆盖全区的格网进行空间系统采样,生成生态脆弱度空间分布图,从景观格局与生态系统敏感性相结合并利用GIS技术对新疆的生态环境进行综合定量的分析和评价。结果表明:(1)未利用地和农用地的景观脆弱度指数较高,草地、林地其次,建设用地和水域最小;(2)相关分析显示,破碎度、盐渍化敏感性、沙漠化敏感性和土壤侵蚀敏感性与景观类型脆弱性间存在着显著的正相关关系,能较好反映区域生态环境问题;(3)区域生态脆弱度的空间格局与研究区实际吻合良好,表现为水平方向上环两大盆地分布,离沙漠腹地距离越近脆弱度越高;垂直方向上生态脆弱度具有随海拔增高坡度变大而增大的趋势;(4)结合研究区实际可知,气候、地形地貌、土壤结构、水资源等自然因素为新疆的生态环境提供背景基础,而人类活动则是重要的调控因素

Effects of olivine on catalytic reforming of toluene

With toluene as the model compound of tar from biomass gasification, the catalytic properties of olivine and nickel catalysts supported on the olivine were analyzed for its performance on the reactions of toluene cracking and toluene/steam reforming in

橄榄石对甲苯催化重整反应的影响

在固定床反应器上,以甲苯为生物质气化焦油的模型化合物,对橄榄石以及其负载镍催化剂对甲苯裂解反应和甲苯/水蒸气重整反应的催化性能进行了研究,并对催化剂进行了SEM、BET、XRD、H2-TPR等表征。结果表明,煅烧使原矿的物化特性发生改变,橄榄石对甲苯裂解反应和重整反应有一定的催化活性。而Ni的引入,使催化剂对甲苯裂解反应的活性有所降低,甲苯的转化率降低2.2%~9.8%;但催化剂对甲苯/水蒸气重整反应的活性升高,甲苯的转化率可高达97.0%,并且载镍橄榄石催化剂对甲苯/水蒸气重整反应有较强的稳定性

Physiological and ecological responses of hetan and chaotan Phragmites australis to salt stress

Characterizing the different physiological and ecological responses of Phragmites australis from two habitats in the Yellow River delta to salt stress can provide important theoretical support for the selection of P. australis types for the ecological restoration of degraded coastal wetlands. The Na+ content, photosynthetic parameters, H2O2 content, antioxidant enzyme activity, malondialdehyde content, and proline content of leaves from hetan（low-salt habitat, riverside） and chaotan（high-salt habitat, high marsh） P. australis grown under salt stress conditions（300 mmol/L NaCl） were compared, along with the Na+ flux of the root growth area. Salt stress significantly increased the Na+ content in the hetan leaves but had no significant effect on that of the chaotan leaves. Furthermore, non-invasive micro-test technology（NMT） revealed greater Na+ efflux in the chaotan plants(（1982.05±122.74） pmol cm-2 s-1 vs.（87.93±12.94） pmol cm-2 s-1, P<0.01)than in the hetan plants(（1574.16±458.90） pmol cm-2 s-1 vs.（-126.88±23.01） pmol cm-2 s-1, P<0.01), which could be attributed to the need for chaotan P. australis to effectively regulate intracellular ion balance. In addition, the photosynthetic rate of the chaotan plants(（16.36±1.09） μmol m-2 s-1 vs.（22.79±0.67） μmol m-2 s-1, P<0.01) was significantly greater than that of the hetan plants(（12.71±0.97） μmol m-2 s-1 vs.（23.81±0.55） μmol m-2 s-1, P<0.01)after 7 d of salt treatment. Salt stress induced significant increases in the H2O2, malondialdehyde, and proline contents of leaves from both P. australis types, as well as in the activity of antioxidant enzymes. Moreover, the activity of glutathione reductase（GR）in chaotan P. australis was increased significantly（（6.90±1.73） U/mgprot vs.（3.54±0.54） U/mgprot, P<0.05）. These results indicate that chaotan P. australis is more adaptable to salt stress than hetan P. australis, as indicated by the greater Na+ efflux of its roots, greater proline content, and greater antioxidant enzyme activity, which promote salt-stress tolerance. Therefore, in the ecological restoration of degraded coastal wetlands in the Yellow River delta, P. australis from the high marsh should be selected as the material for vegetation restoration

GaAs基半导体激光器热特性

对GaAs基808nm半导体激光器进行恒流老化试验，并利用电学法观察退化过程中激光器有源区温度变化和热阻，发现有源区温度随老化时间明显上升，而热阻没有明显变化，同时测试了老化过程中激光器的电学和光学特性，经分析，激光器失效的主要原因是有源区载流子非辐射复合增加，引起激光器有源区温度上升，从而说明电学法热特性测试是检测激光器退化的有效方法之一，为进一步提高激光器的热管理技术和改善其热特性奠定了一定的基础

Carbon and nitrogen stable isotopes variations in different tissues of macrobenthos in the intertidal zone

近年来,稳定同位素技术已被广泛应用于食物网研究中。然而,生物样品取样部位对食物网构建的影响的研究相对少见。大型底栖动物作为潮间带食物网的重要组成部分,在食物网研究中有必要对其采样部位进行统一,以增加研究结果的准确性及可比较性。本研究选取黄河三角洲和烟台潮间带10种代表性的大型底栖动物,比较δ13C和δ15N在不同采样部位中的差异。结果显示,对于大多数底栖动物而言,采样部位将直接影响到δ13C和δ15N的测定结果。当底栖动物作为摄食者,需分析其食性和营养级时,应统一采用肌肉组织,如贝类的闭壳肌或足部肌肉,蟹类的鳌足肌肉,鱼类的背部肌肉;当底栖动物作为被摄食者,需分析次级消费者的食性和营养级时,除多毛类采用去除消化道内容物的体壁外,其他种类应选取整体(难以被消化的组织除外),如贝类的软体部,蟹类肌肉与鳃等的混合组织

Genetic Variation and Spread of Spartina alternifora in the Yellow River Delta

Spartina alternifora has been introduced into the Yellow River Delta since 1990.It spreads very rapidly and threatens the safety of the ecosystem.Investigating the genetic variation of Spartina alternifora can help understanding the mechanism of invasion and provide basic knowledge for the management of this invasive species.The genetic structure and diversity of four populations of Spartina alternifora(Pop 1,Pop 2,Pop 3 and Pop 4) at 13 loci were analyzed using microsatellite markers.The results revealed that the genetic diversity of Spartina alternifora in the Yellow River Delta was high.The average observed allele number(Na) was 7.385,the effective allele number(Ne) was 3.636,the Nei's genetic diversity was(0.700±0.094),the Shannon index was(1.453±0.343),and the proportion of polymorphic loci(P) was 100%.The Na,Ne,Nei's genetic diversity and Shannon index of Pop1 was the lowest,while those of Pop2-Pop4 were similar.However,the genetic differentiation(F_(st)=0.121) and the gene flow(Nm=1.825) among populations were medium.The genetic similarity among Pop 1-Pop 3 was high while the genetic similarity between Pop 4 and Pop 1-Pop 3 was low.As we known,Pop 3 was the initial and unique introduced population.The genetic structure of 4 populations suggested that firstly Pop 3 dispersed to Pop 4,and then Pop 3 dispersed to Pop 1 and Pop 2.The population dispersal order was not associated with the geographic distance of these populations,for the reason that the seeds of Spartina alternifora could disperse by sea water over a long distance.Therefore,developing environment-friendly herbicide to make Spartina alternifora in fecund could be a good way to control its invasion