赣闽浙三省接合区砂金资源的分布与沉积学特点

赣闽浙三省接合区砂金资源分布广泛,尤以赣东北乐安江、昌江水系最富。本文是在对该区野外调查,取样分析和典型砂金矿床、矿点地质环境分析的基础上,认为冲积型砂金富集与矿源层分布,水系发育规模及地貌条件,含金物质搬运距离,水动力条件,沉积界面微地貌及合金物质沉积后埋藏状况有密切关系,掌握砂金沉积学特点有利于资源的勘探和开发。     

Atomic force microscopy study on the microtopography of natural organic matter and newly formed hydrous MnO2

To understand the water purification mechanism of potassium permanganate as a coagulation-aid during the preoxidation process, the microtopography of its reductive products, the newly formed hydrous manganese dioxide and the aged hydrous manganese dioxide, was investigated. The morphology of natural organic matter (NOM) adsorbed by the newly formed hydrous manganese dioxide was also compared with that of NOM alone. By using the tapping mode atomic force microscopy (AFM), the observation results show that the newly formed hydrous manganese dioxide possess a perforated sheet (with a thickness of 0–1.75 nm) as well as some spherical particle structures compared with the hydrous manganese dioxide with 2 h aging time, which demonstrated that the newly formed hydrous manganese dioxide had a large surface area and adsorption capacity. When 1 mmol/L newly formed hydrous manganese dioxide was added, the microtopography of NOM molecules shifted from a loosely dispersed pancake shape (with adsorption height of 5–8.5 nm) to a densely dispersed and uniform spherical structure. These results provide a valid proof that it is the perfect adsorption capability of the newly formed hydrous manganese dioxide that might result in the coagulation aid effect of potassium permanganate preoxidation. Translated from Environmental Science, 2006, 27(5): 945–949 [译自: 环境科学]     

Influences of Microhabitat Constraints and Rock-Climbing Disturbance on Cliff-Face Vegetation Communities

Abstract:  Many researchers report that rock climbing has significant negative effects on cliff biota. Most work on climbing disturbance, however, has not controlled for variation in microsite characteristics when comparing areas with and without climbing presence. Additionally, some researchers do not identify the style or difficulty level of climbing routes sampled or select climbing routes that do not represent current trends in the sport. We solved these problems by sampling climbing areas used by advanced "sport" climbers and quantifying differences in microtopography between climbed and control cliffs. We determined whether differences in vegetation existed between pristine and sport-climbed cliff faces when microsite factors were not controlled. We then determined the relative influence of the presence of climbing, cliff-face microtopography, local physical factors, and regional geography on the richness, abundance, and community composition of cliff-face vascular plants, bryophytes, and lichens. When we did not control for microsite differences among cliffs, our results were consistent with the majority of prior work on impacts of climbing (i.e., sport-climbed cliff faces supported a lower mean richness of vascular plants and bryophytes and significantly different frequencies of individual species when compared with pristine cliff faces). When we investigated the relative influences of microtopography and climbing disturbance, however, the differences in vegetation were not related to climbing disturbance but rather to the selection by sport climbers of cliff faces with microsite characteristics that support less vegetation. Climbed sites had not diverged toward a separate vegetation community; instead, they supported a subset of the species found on pristine cliff faces. Prior management recommendations to restrict development of new climbing routes should be reevaluated based on our results.     

原子力显微观测新生态水合二氧化锰与天然有机物的微观吸附形貌

采用云母片吸附的方式,较好地捕捉到了新生态水合二氧化锰的微观结构,并采用轻敲模式下的原子力显微成像技术,对其吸附天然有机物(NOM)前后的微观形貌进行了观测.与陈化2 h后的水合二氧化锰相比,新生态水合二氧化锰呈现出不定形的穿孔层状结构(厚度仅为0～1.75 nm)和球形颗粒结构,具有大的比表面积和附着能力.当向NOM中加入1 mmol/L新生态水合二氧化锰后,NOM分子的吸附形貌由松散分布的扁平粒状结构(吸附高度为5～8.5 nm)转变为密集分布、水平尺寸均匀的球形结构,表明了NOM分子容易以水合二氧化锰为吸附中心包裹在其表面.从直观上进一步证实了新生态水合二氧化锰的除污染效能,为高锰酸盐的预氧化助凝机理提供了有力的依据.     

SIMPLE MEASUREMENTS OF SOIL SURFACE MICRORELIEF CHARACTERISTICS1

ABSTRACT: Soil surface roughness and the topographic orientation of microrelief influence runoff and water storage. Distances measured following the surface of the microrelief and horizontally across the area with the microrelief can be used with the number of microridges or microhills to estimate the average cross-sectional areas of the depression, the microslope angles, and crest heights. Microridge sideslope angles which effect the rate of runoff were estimated reasonably well in field plots by the method.     

絮凝基因的克隆及其絮凝机理分析

分离到1株具有强絮凝特性的芽孢杆菌Bacillus sp. F2,絮凝率达84%,并构建絮凝基因组文库.以絮凝菌F2为实验材料,提取基因组总DNA,经限制性内切酶Sau3AI部分酶切后,与用限制性内切酶BamHI完全酶切的载体PUC19DNA连接,并转化到感受态细胞JM109中.然后将其涂布于含氨苄青霉素的LB培养基上,过夜培养后,经蓝白斑筛选,构建了絮凝基因组文库,该文库包含3.5×10⁴个重组子,经测定文库滴度为3.5×10⁵　pfu/mL.从文库中筛选而获得1株表达絮凝活性的大肠杆菌阳性克隆子FC2.序列分析得出该克隆序列为新的絮凝基因.絮凝试验测定FC2的絮凝率为90%,稍高于原絮凝菌F2,高于受体菌JM109(6.9%).红外光谱分析证明FC2的絮凝有效成分与F2一致,说明FC2絮凝性状遗传于原絮凝菌F2.采用轻敲模式下的原子力显微镜成像技术、Zeta(ξ)电位测定对加入絮凝剂FC2与加入絮凝剂F2、不加入絮凝剂的絮凝微观形貌进行了测定.原子力显微成像显示,加入克隆菌FC2发酵液的高岭土悬浮液(5‰的高岭土水溶液)形成的絮凝体出现较大而且紧密的球形颗粒结构,且表面积粗糙,凹凸程度大,具有大的比表面积和吸附液体悬浮颗粒的能力.向高岭土悬浮液中加入克隆菌FC2发酵液后,絮凝颗粒由不定形且松散的结构转变为密集分布、水平尺寸均匀的球形结构,表明克隆菌FC2发酵液中的凝集素容易以高岭土悬浮颗粒为中心吸附在其表面,而且絮凝试验中絮凝率达90%,从更直观上进一步证实了克隆菌FC2发酵液的除污染效能.Zeta(ξ)电位测定结果表明,离子键作用强度不同,致使絮凝形态存在着差异,为研究生物絮凝剂的絮凝机理提供了有力的依据.     

滨海湿地退化区鸟类刨坑觅食行为促进植被的恢复

鸟类是滨海湿地生态系统中非常重要的组成部分,也是能够通过自身行为影响非生物环境以及生物过程的生态系统工程师。了解鸟类在滨海湿地生态系统中的生态系统工程效应,对于开展滨海湿地的生态修复具有重要作用。通过野外调查研究由灰鹤（Grus grus）和斑嘴鸭（Anas poecilorhyncha）主导的滨海鸟类的刨坑觅食行为对植被退化区的地形以及土壤环境理化指标的影响,进而促进盐地碱蓬（Suaeda salsa）植被的恢复。结果表明：鸟类在植被退化区的刨坑觅食行为改变了退化区的微地形及土壤环境,使得土壤硬度和土壤盐度显著降低,而土壤含水率和土壤碳氮营养指标则显著高于未经鸟类影响的退化平坦区域;另外,鸟类活动改善的凹坑微地形环境能够显著提高盐地碱蓬的种子保留量、幼苗定植量和成株存活量,有效促进盐地碱蓬在植被退化区域的恢复。通过鸟类改变微地形进而促进植被恢复的启发,提出可以尝试人为模拟改造退化区的微地形环境,以通过人为干预的方式促进滨海湿地退化区的植被恢复,对滨海湿地的生态修复具有重要指导意义。     

臭氧氧化对天然有机物在氧化铝表面吸附行为的影响

为进一步明确臭氧预氧化对颗粒的脱稳作用,选用氧化铝（α-Al₂O₃）作为悬浮颗粒,考察了臭氧氧化后天然有机物（natural organic matters,NOM）特性及吸附行为的变化.结果表明,臭氧氧化能够破坏NOM的芳香结构,SUVA值降低25%～35%,氧化后酸性官能团含量增多,总酸度增加0.3～1.4 mmol·g^-1,分子量和极性的变化与NOM的性质有关;有机物初始浓度相对于臭氧投量较低时,NOM的溶解性增强,与其酸性官能团增加产生的吸附促进作用相抵消,因而吸附性能出现不变甚至降低的现象;有机物初始浓度较高时,臭氧能够起到强化NOM吸附的作用.采用2.5　mg·L^-1臭氧进行氧化后,以商用腐殖酸为代表的NOM的吸附形貌,由密集分布的球形对称聚集结构向网状结构过渡,分子之间的交联作用十分明显,吸附高度低于其氧化处理前,云母的表面覆盖率较氧化前略有提高.     

Changes in groundwater levels and the response of natural vegetation to transfer of water to the lower reaches of the Tarim River

Restoration and reconstruction of the degraded Tarim River ecosystem is an important challenge.A goal of an ecological water conveyance project is to protect and restore the natural vegetation in the lower reaches of Tarim River by transferring water from Bosten Lake,through the river channel,to the lower reaches.This study describes the changes in groundwater depth during the water transfer and the respondence of riparian vegetation to alterations in groundwater levels.The results indicate that groundwater depth along the Tarim River channel has a significant spatial-temporal component.Groundwater levels closest to the river channel show the most immediate and pronounced changes as a response to water transfer while those further away respond more slowly,although the observed change appears to be longer in duration.With a rise in the groundwater level,natural vegetation responded with higher growth rates,biomass and biodiversity.These favorable changes show that it is feasible to protect and restore the degraded natural vegetation by raising the groundwater depth.Plant communities are likely to reflect the hysteresis phenomenon,requiring higher water levels to initiate and stimulate desired growth than what may be needed to maintain the plant community.Because different species have different ecologies,including different root depths and densities and water needs,their response to increasing water availability will be spatially and temporally heterogenous.The response of vegetation is also influenced by microtopography and watering style.This paper discusses strategies for the protection and restoration of the degraded vegetation in the lower reaches of the Tarim River and provides information to complement ongoing theoretical research into ecological restoration in arid or semi-arid ecosystems.