Temporal-spatial dynamics of distribution patterns of microorganism relating to biological soil crusts in the Gurbantunggut Desert

Biological soil crusts serve as an important biological factor contributing to the sand fixation. This study was conducted to investigate the temporal-spatial variability of microorganism in crusts relating to locations, soil layers of sand dunes and seasons. At moss-dominated inter-dune areas, higher soil nutrient and water concentrations were likely to maintain the microbial activities. Bacteria showed the highest capabilities of settlement and growth in inter-dunes in both spring and autumn. Soil water content reached the highest value in soil crusts in the inter-dune areas, especially in spring. Variations of quantities of actinomyces and fungi basically showed the consistent trend in different locations of sand dunes. With the deepening of soil layers, vertical distribution of quantities of each microorganism group showed different characteristics because environmental factors fluctuated in both spring and autumn. Among different microorganism groups, bacteria were predominant, actinomyces the next and fungi the least in both spring and autumn in all soil layers （0-20 cm）. The proportion of bacteria and soil water content were higher in spring than those in autumn in all soil layers （0-20 cm）. No consistent trends were found in actinomyces and fungi. The results showed that the quantities of microorganisms were significantly positive correlated with organic matter content, soil water content, total N, total P, available P, available K, pH, electrical conductivity, total salt content,catalase, urease, phosphatase and alkaline phosphatase.     

不同演替序列的藻结皮净光合速率日变化特征

研究了腾格里沙漠东南缘自然植被区,51龄和27龄人工植被区藻结皮的净光合速率(P_n)在春季和夏季的变化特征,并同步测定了藻结皮的Chla含量.结果表明:三个植被区Chla差异显著(P0.05),依次为51龄(1.84 mg/cm~2)27龄(1.23 mg/cm~2)自然植被区(0.74 mg/cm~2);藻结皮的P_n为0.55～2.8μmol/(m~2·s).春季三个植被区藻结皮的P_n呈单峰型,峰值出现在11:00,自然植被区、51龄和27龄植被区藻结皮的P_n分别为1.77,2.7,2.0μmol/(m~2·s).夏季三个植被区藻结皮的P_n呈双峰型,双峰分别出现在11:00,17:00.11:00时,自然植被区、51龄和27龄植被区藻结皮的P_n为2,2.8,2.2μmol/(m~2·s),17:00时P_n分别为1.8,2.3,1.6μmol/(m~2·s).在两个季节,51龄藻结皮的净光合速率均显著高于27龄和自然植被区的.     

Ecological and environmental explanation of microbiotic crusts on sand dune scales in the Gurbantonggut Desert, Xinjiang

Results obtained from the field investigation and the analysis in laboratory show that many species of microbiotic crusts of lichens, mosses and algae develop extensively in the Gurbantonggut Desert, Xinjiang. The formation, species and distribution are closely related to the environmental conditions at the different positions of sand dunes. The animalcule crusts develop mainly on the mobile or semi-mobile sand surface of dune tops, the alga crusts develop mainly at the upper to middle parts of dune slopes, the lichen crusts develop at middle and lower parts of dune slopes, and the moss crusts are mainly distributed at the lower part of dune slopes and the interdune lowlands. The species, thickness and developing degree of microbiotic crusts increase from the upper part to the middle and lower parts of dune slopes and the interdune lowlands, and an obvious contrast between the microbiotic crusts and the different species of plant communities forms. The development and differentiation of microbiotic crusts at the different positions of dunes are the ecological appearance and the natural selection of synthetic adaptability of the different microbiotic crust species to the local environmental conditions, and are closely related to the ecological conditions, such as the physiochemical properties of soils and stability of topsoil texture.     

不同有机质含量水泥加固土微观结构分析

为了研究有机质对水泥加固土微观结构的影响,采用水泥作为固化剂对不同有机质含量的软土进行加固,并利用扫描电子显微镜采集了达到养护期的各试样的微观结构照片,同时利用WD-5图像处理系统对微观结构图像进行处理,提取各试样结构单元体和孔隙的大小、形态及定向性等结构要素作为评价指标.分析了各结构参数随土中有机质含量的变化规律.结果表明:有机质含量越高,试样中等效直径较大的单元体含量越少,小单元体含量相对增加;大孔隙含量相对增加,小孔隙含量相对减少.试样结构单元体及孔隙的形态特征及定向性与有机质含量没有明显的相关关系.该成果对有机质影响水泥加固软土效果的研究具有一定的参考价值.     

植物固沙工程对土壤生物活性的影响

通过采集半流动沙丘、5年、10年和22年生小叶锦鸡儿人工固沙植被的土壤样品,对各类型土壤的养分状况、微生物和主要土壤酶活性进行对比研究。土壤按5层取样：0～1O,10-20,20-30,30-40,40-50cm。结果表明,采用植物固沙工程固定沙丘后,表层土壤（0-10cm）有机C和全N含量显著增加,同时土壤生物活性也大幅度提高,土壤微生物生物量C和N的含量以及土壤脲酶、蔗糖酶、磷酸单酯酶和多酚氧化酶活性均明显提高。这种改良效应随着年龄增长而逐渐增加。土壤微生物生物量C与土壤总有机C含量,微生物生物量N与土壤全N之间均存在着明显的正相关性。     

一种自动跟踪土微观变形的试验方法

土微观结构的变形性能对工程力学性质起着非常重要的作用.计算机视觉数字化技术的发展,为岩土领域土微观结构变形分析提供了一种新的研究方法.为了研究土颗粒在动载条件下的运动特性,利用计算机自动跟踪技术对土的微观变形进行了动态测量.将圆柱形土样对称地分成两部分,取其中一部分放于有一面是透明玻璃的半圆柱形加压舱内,通过玻璃窗口,自动控制台上的长距离,远心显微镜头不仅可以拍摄到土颗粒变形的全过程,同时利用变模板方法通过实时序列图像分析就可以跟踪到移动的土颗粒.试验证明该技术能够成功跟踪土颗粒并能十分方便地得到土微观结构的变形参数.     

基于模型试验的群桩沉桩挤土效应微结构分析

基于静压群桩模型试验,运用扫描电镜获取了压桩前后土样的微观结构照片,并运用图象处理技术提取了群桩沉桩前后不同位置处土体微观结构参数,通过对比分析认识到:沉桩前桩周土体结构疏松,孔隙形状不规则,群桩压入后桩群中土体孔隙明显减小,孔隙的方向性增强;群桩压入后,等效直径、平面孔隙率、孔隙周长在地表及一定深度内部有所减小:孔隙个数增多,有土体被挤密的现象,而且随着深度的增加这种挤密效果更加明显;压桩后土颗粒的圆度和形态比变大,颗粒在几何形态上向扁长方向发展,且孔隙定向性集中于一到两个方向.     

桔黄假单胞菌JD37与LaCl3联用对植物生长和土壤生物活性的研究

桔黄假单胞菌JD37是一株兼具植物促生与生物防治的根际促生菌,LaCl₃是一种稀土元素.从植物生长和土壤生物活性两方面研究JD37与LaCl₃联用效果.结果表明：联合处理对菠菜的促生效果优于单独接种JD37或浇灌LaCl₃溶液.30天时,联合处理菌体定殖数量高于单独接种JD37菌株,根际土壤和根内的菌体定殖数分别为5.00×10₄cfu/g和7.63×10₃cfu/g.菠菜总叶绿素含量在联合处理后达2.73mg/g.土壤酶活性检测发现,联合处理均能显著提高4种土壤酶活性,对土壤纤维素酶的活性增加效果最显著,与单独接种JD37或浇灌LaCl₃相比,土壤纤维素酶活性提高了66.08%和70.93%.联合处理高效维持土壤细菌和放线菌数,微生物数量为1.34×10₇cfu/g和4.73×10₆cfu/g.本实验旨在为JD37联合LaCl₃的复合微生物肥料在农业生产中使用提供数据支持.     

Spontaneous formation of tubular microstructure vesicle from PTA／SDS system

Spontaneous vesicle formation and transformation of vesicle to tubular microstructure have been observed in aqueous mixtures of tri-(n-dodecyl-dimethyl-hydroxy-propylammonium chloride) phosphate (PTA) and sodium dedecyl sulfate (SDS), which is supported by negative-staining transmission electron microscopy (TEM), scan electron microscopy (SEM) and dynamic light scattering (DLS). Spherical vesicles aggregate to tubular microstructures with their diameters and lengths respectively of about 100 and 7000 nm in the freshly prepared sample at the molar ratio of PTA/SDS=3/7 and a total surfactant concentration of 0.01 mol/L. The diameter, the length and the quantity of tubular structures all increase with the increase of the total concentration of surfactant and the sample aging.     

Loess in the Tian Shan and its implications for the development of the Gurbantunggut Desert and drying of northern Xinjiang

Eolian loess is widely distributed on the various geomorphic surfaces between 700–2400 m a.s.l. on the northern slope of the Tian Shan. It is formed in a synchronous manner with dust transported from the Gurbantunggut Desert in the Junggar Basin. The thickest section of loess was found in the Shawan and Shihezi regions. Paleomagnetic and climatic proxy analyses of over 71 m of a loess-paleosol sequence on the highest terrace of the Qingshui He (River) in the Shawan show that the paleomagnetic Bruhues/Matuyama (B/M) boundary lies at the bottom of paleosol S8, at a depth of 69.5 m, and the bottom of the sequence was estimated to be ∼0.8 Ma. This implies that the extremely dry climatic conditions in the Junggar Basin and the initial Gurbantunggut Desert were present at least by 0.8 Ma. High-resolution grain size series demonstrate that this area and desert expansion experienced two dramatic periods of desert expansions that occurred at ∼0.65 Ma and 0.5 Ma, respectively; and the subsequent continuous enhancement led to the environment presently observed. This tremendous environmental effect, caused by large-scale expansion of the desert and arid region of inner Asia, might be an important driving force for the global temperature drop that occurred in the mid-Pleistocene.     

Respondence and feedback of modern sand deserts to climate change--A case study in Gurbantunggut Desert

The research on the respondence and feedback of modern sand deserts to the climate change is an important component part in the studies on the global climate change. Deserts respond to the climate change, meanwhile, they affect the climate with their feedback of peculiar environment during the respondence. Many researches on desert climate have been carried out at home and abroad. However, there is little research on the respondence and feedback of modern fixed, semi-fixed and mobile deserts in arid areas to the climate change, in which the factor analysis as well as the parameter changing effects is especially the difficult problem all along. In this note, the parameters of the respondence and feedback of Gurbantunggut Desert to the climate change are measured and analyzed, some variable parameters of water-heat exchange are obtained, and a numerical model of desertification is developed according to a series of climate change of about 40 years and the variable relations of meteorological and physical features of the sand surface in Gurbantunggut Desert.     

无患子初果期人工林土壤和叶片C、N、P化学计量特征

【目的】了解无患子无性系人工林初果期C、N、P化学计量差异及其养分元素间相互作用。【方法】以福建省建宁县无患子无性系媛华人工林为研究对象,选择其初果期具有代表性的地段,分别设置3块20 m×10 m样地,测定了土壤(有机碳、全氮、全磷、全钾、有效磷、有效钾、碱解氮)和叶片(碳、氮、磷、钾)养分含量,并计算土壤和叶片的碳、氮、磷元素计量比(记为C/N、C/P、N/P),分析处于初果期的无患子人工林土壤和叶片养分含量及化学计量特征。【结果】无患子无性系媛华人工林土壤有机碳、全氮、全钾、有效磷含量在初果期随林龄增大而增加,土壤全磷变化不明显且含量较低(0.36 g/kg);土壤C/N随林龄增加逐步减小,而C/P和N/P有一定增加趋势;叶片碳和磷含量随林龄增加而逐渐增大,氮含量逐渐降低,钾含量无显著变化,其人工林叶片C/N有一定程度升高,C/P和N/P随林龄增加出现逐渐降低的趋势。此外,无患子人工林土壤有机碳和全氮含量具有显著正相关;无患子叶片碳与氮之间呈负相关,但碳与磷、钾呈正相关。同时,无患子无性系人工林叶片C含量与土壤有机碳含量在0~20和≥40~60 cm的土层呈显著正相关,在≥20~40 cm的土层中呈极显著正相关;叶片磷P含量与土壤有机碳含量在0~20 cm呈极显著正相关,在≥20~40和≥40~60 cm的土层中呈显著正相关;N/P与土壤有机碳含量在0~20 和≥40~60 cm呈极显著负相关,在≥20~40 cm土层中呈显著负相关。【结论】在无患子人工林初果期,土壤养分主要受P的限制,因此,苗木定植后的结果初期,可适当增加磷肥的投入。     

宁夏南部地区水土流失的形成机理与防治对策

根据宁夏南部黄土丘陵区野外调查及西吉县夏家大路黄土结构样的电镜扫描结果，从其黄土地形地貌、显微结构类型及水动力状况，分析了研究区内侵蚀程度高、危害性大的水土流失灾害的致灾机理。论述了该地区水土流失的现状与危害，认为自然因素和人类活动作用的共同叠加是黄土区水土流失加剧的重要原因。提出了扩大植被覆盖率，减少降雨对地表的冲刷；农业生产中采用沟垄、坑田、壕田耕作法，以保持水土；工程建设中采用化学法、强夯法和灰土桩法，加固湿陷性黄土地基；配合系统的技术性对策，建立相应的社会性对策等防治措施。     

长安县黄土中的风化壳与环境研究

据野外调查和室内鉴定 ,在长安县城南布容期 0 78- 0MaBP形成的黄土剖面中确定了三个时期的风化壳 ,它们由第 1 ,4,5层古土壤和风化破碎黄土构成 .黄土中的风化壳是红褐色古土壤在特定的气候条件下转变而成的 ,厚度在 3～ 6m之间 ,风化壳剖面常由 3～ 4个层次构成 ,发育时间为 5～ 1 0× 1 0 4a不等 .风化壳上部是发育好的红色古土壤 ,中部是含铁质胶膜的风化破碎黄土 ,下部是不含铁质胶膜的风化破碎黄土 .粘土矿物分析表明 ,黄土中的风化壳为伊利石 蒙脱石型和高岭石型之间的过渡类型 .黄土中风化壳发育时的年均降水量在 95 0～ 1 0 0 0mm之间 ,是黄土高原降水丰富的气候事件的显示 .风化壳的发育证明黄土中有些古土壤确属淋溶型森林土壤 ,当时亚热带气候至少迁移到了黄土高原东南部     

新型组合式分层生物滴滤池启动性能研究

考察了组合式分层生物滴滤池与普通生物滴滤池在相同条件运行初期污水处理效果及生物膜特性.结果表明分层生物滴滤池出水水质能够更快的达到稳定,出水水质波动范围较小,去除率更高,且生物膜活性也较高.说明组合式分层生物滴滤池较普通生物滴滤池有一定的优越性.     

不同生态因子对青藏高原东缘沙化区生物结皮中藻类生长发育的影响

为研究不同生态因子对青藏高原东缘沙化区藻类生长发育的影响,以筛选出沙化区藻类生长的最适条件,采集沙化区不同区域和深度的土样后,装入无菌袋并保存于-20℃冰箱.制备不同浓度的土壤悬液,均匀接种于无菌BG11固体培基上,在光/暗=16 h/8 h,25℃条件下培养1个月.挑取单一的藻落接种于BG11液体培养基中进行纯化培养...     

热处理工艺对Mg-RE-Zn-Zr系合金显微组织及力学性能的影响

通过气体保护制备了Mg-RE-Zn-Zr[RE-Ce-40La（wt％）的富铈稀土]合金,并对合金进行了热处理,测试了不同状态下合金的硬度、抗拉强度及伸长率等力学性能,采用光学显微镜、X射线衍射仪及扫描电镜对合金显微组织、拉伸断口进行了分析。结果发现,采用T6热处理工艺后,合金的晶粒尺寸明显细化,硬度、抗拉强度、屈服强度和伸长率显著提高,分别提高了11％,24％,7．3％和102％。     

芡实生物学特性的研究

试验采用对角线取样法,每点取5株芡实作为研究对象,从幼苗期开始对芡实的植物学特征,生长状况以及农艺性状等方面进行研究．结果表明,芡实叶柄长156．5cm,直径2．6cm,单茎重0．94kg,单株叶柄数10个,产量为20848．4kg·hm-2;芡实种子单粒重0．22g,直径6mm,单株果数15个,产量647．1kg．hm-2,每公顷可为农民增收99572．1元,具有非常高的经济价值和广阔的发展前景．     

杂多酸金属簇的合成进展及其在生物治疗方面的应用

多金属氧酸盐(POM)由于其独特的物理、化学性质,近年来受到人们越来越多的关注.在POM的研究领域,过渡金属/稀土金属与POM的配位化学更是其中重点之一.它们与聚合物(如淀粉、明胶、壳聚糖等)的复合物纳米粒子在肿瘤治疗方面具有低毒、高效等优点.主要综述了杂多酸金属簇的合成进展及其生物治疗方面的研究.