国外土壤微形态学研究的进展

土壤微形态学从20世纪30年代发展至今,取得了很大的进步,并广泛应用于土壤学各个领域,解决了很多土壤学问题。越来越多的学者应用土壤微形态学方法进行其他学科领域的研究,并取得了很好的结果。与国内比较,国外土壤微形态学各方面的发展都更早、更为成熟。从国外土壤微形态学的发展简况以及土壤微形态学在其他学科领域的应用研究最新进展进行报道,如土壤发生与分类、土壤肥力与土壤环境、考古与第四纪等,以期对国外土壤微形态学的研究成果做一初步的小结和为国内土壤微形态学的发展提供一定的参考借鉴。

土壤微形态学的研究进展与展望

作为土壤学的一个重要分支学科,土壤微形态学自从创建以来,通过国内外学者的创新性研究,在其研究技术与研究内容方面都取得了长足的进展。简单回顾了土壤微形态学的发展历程,综述了土壤微形态研究的主要进展,并对其未来的发展作出了展望。

土壤/橡胶粘附界面土壤表层微形态SEM研究

利用扫描电镜观察了土壤/橡胶粘附系统自然风干后界面处土壤表层微形态,发现土壤表层呈现各种尺度的粗糙结构,微观形态特征与界面所受法向压力的大小有关。文中还对土壤与固体外物表面粘附的机理进行了分析,并依据粘附界面土壤固相形成特征,探讨了土壤粘附界面水膜状态及其对土壤粘附强度的影响。

新时代土壤地理学的发展现状与趋势

土壤地理学是研究土壤时空分布规律、形成过程及其资源环境效应的土壤学学科分支,其主要目标和任务是理解土壤形成演化的关键过程与影响因素并预测未来土壤-环境的共同演化特征,揭示土壤资源分布规律、利用前景和保护对策,为农业、生态环境保护等提供科学依据,支撑土壤普查、耕地保护等国家目标。21世纪特别是新时代10年以来土壤地理学取得了一些重要的进展,研究对象和内容也发生了很大的变化,逐渐向以土壤为核心的地球表层系统科学发展,高强度人为活动和全球气候变化背景下的土壤时空演变研究愈加活跃。土壤地理学主要发展趋势包括土壤信息获取方式正在发生变革,数字土壤制图向融合过程机理与数据驱动发展,土壤时空信息的应用范围更加广泛。未来土壤地理学优先发展领域包括:以关键带研究带动土壤发生和演变研究的革新,基于多传感器的土壤综合观测原理与技术,多尺度数字土壤制图与时空变化预测等。

土壤微形态及其应用研究进展

土壤微形态学是土壤学的一个重要分支学科。它在上一世纪 30年代建立以来 ,解决了土壤学中许多问题。我国在土壤微形态研究上起步较晚 ,但也取得了一些好的研究结果。本文从国内外土壤微形态学研究的进展 ,包括基本概念。

神农架山地土壤的微形态研究

神农架天门垭山地棕壤的古红壤残遗特征表明,本区曾经历多次新构造隆升运动。土壤微形态研究证明了神农架3000m以上顶峰确实存在着灰土类型。

《土壤微形态研究理论与实践》出版

由何毓蓉、张丹编著的《土壤微形态研究理论与实践》是一本关于土壤微形态的理论和实际应用的专门著作,40万字,2015年8月由地质出版社出版。全书以土壤微形态学的创立和发展为开篇,介绍了土壤微形态学的基本概念和与其他学科的相互关系。根据目前收集到的国内外有关学者的文献和作者的长期工作经验,详细介绍了土壤微形态学研究的技术和方法,包括野外样品的采集、土壤薄片的制备技术和方法等。

土壤时空变化研究的进展与未来

理解和表征土壤的时空变化是土壤学的基本任务,也是评估和合理发挥土壤功能的重要前提。土壤的时空变化与气候环境变迁、岩石圈风化、地表物质迁移、生物地球化学循环等圈层变化过程相耦合。围绕土壤时空变化研究的新近进展,本文综述并展望了土壤形成和演变过程、土壤形态学、土壤调查、土壤分类、数字土壤制图与土壤退化的发展态势。未来土壤时空变化研究的关键科学问题主要包括:地球表层系统中土壤与环境要素之间的多过程耦合机理与模拟、多尺度土壤-环境关系与模拟、多元土壤信息的融合机理与数据同化。未来重点研究领域将涉及到关键带科学引领的土壤形成和演变研究、多尺度数字土壤制图与时空变化预测、基于多传感器的土壤综合观测原理与技术、完整和详尽的国家和全球土壤资源清单及共享平台建设、区域土壤资源退化机理及其功能恢复。

基于SFS的土壤三维结构恢复及孔隙度计算

【目的】为了快速、准确地计算土体结构和孔隙度等特征,提出一种基于SFS算法(shape from shading)的土壤三维结构重构方法。【方法】首先获取土壤的灰度显微图像,根据朗伯表面漫反射模型建立土壤的光照方程;然后利用泰勒展开法和雅克比迭代法求解光照方程,计算出像素点高度值并实现土壤的三维重建;最后根据正态分布校正高度值计算土壤孔隙度。【结果】实验结果证明,该方法计算得出的孔隙度与环刀烘干法测得的结果相差0.81%,误差率1.75%。【结论】利用显微图像中土壤结构的三维信息,可以客观准确地计算出土壤孔隙度等物理特征。

应用于土壤系统分类的土壤微形态学研究进展及展望

土壤微形态学从上世纪二十年代发展至今,取得了很大的进步,并广泛应用于土壤学各个领域,解决了很多土壤学问题。越来越多的学者应用微形态学方法进行土壤形成演化和系统分类研究,并取得了很好的结果。近年来中国土壤系统分类研究取得了长足的进步,在开展土壤系统分类制的基层分类上,应当把土壤微结构作为重要依据,以丰富土壤基层分类的内容,提高我国土壤系统分类在基层分类研究和应用上的水平。本文试从土壤形成演化和土壤系统分类中土壤诊断层和诊断特征两方面叙述土壤微形态学的应用。特别是总结了中国土壤系统分类中人为土、富铁土、变性土及其它土纲应用土壤微形态的研究成果。最后提出加强人为土、土壤基层分类的微形态研究以及土壤微形态的动态定量研究是土壤系统分类中土壤微形态学发展的重要趋势。

黄河三角洲土壤的微形态特征

对近代黄河三角洲上有代表性的土壤剖面进行偏光显微镜、扫描电镜、透射电镜观察.结果表明,土壤结构发育很差,暗色矿物较多,骨骼颗粒仍保持着冲积形貌.土壤孔性不好,很少形成良好的通气孔隙.土体中碳酸盐聚集明湿,铁、锰形成物也较多,说明土壤发育处于初始阶段,其土壤抗蚀力弱,易退化,故在开发利用中应引起重视.

Age and Some Genetic Characteristics of Vertisols in China

The ages of organic matter of some dark-colored horizons and calcareous concretions in some Vertisols from tropical, subtropical and warm-temperate zones of China were studied using radiocarb on dating method. The relationship between soil age and genesis of Vertisols was also expounded based on the study of their genetic charactens-tics and micromorphological features. The results show that although Vertisols have developed for a relatively long time, their weathering and soil forming process are weak and young with little horizonation. This is closely related to their special geochemical soil forming environment. Low-lying terrain, heavy texture, clay minerals dominated by montmorillonites and alternative drying- wetting climate give rise to the vertic features expressed in intense swelling-shrinking and cracking-closing in soils. As a result, the soil development and soil leaching process are resisted, and the climatic effect on the horizonation is impeded. Moreover, pedoturbation eliminates the horizonation in the upper part of soil profile, and postpones their evolution into zonal soils. So Vertisols show certain pedogenic inertia and stay at relatively young developmental stage. Therefore, Vertisols are intrazonal soils dominated by local soil forming factors such as the relief and parent materials.

Chemical Forms of Mercury in Soils and Their Influencing Factors *1

Experiments were carried out to study the transformation of mercury in soils. Results showed that Hg 2+ was immediately converted into other forms once it entered into soils. Bentonite, humus or CaCO 3 accelerated the transformation of Hg 2+ by various mechanisms. Bentonite could convert Hg 2+ into residual form eventually, and application of CaCO 3 enhanced the formation of inorganic Hg. Humus competed strongly with clay minerals for binding Hg 2+ , thus increase of soil humus content led to increased formation of organically bound Hg.

Changes of root morphology and Pb uptake by two species of Elsholtzia under Pb toxicity

Elsholtzia argyi and Elsholtzia splendens, which are Chinese endemic Pb/Zn mined and Cu mined ecotype respec- tively, were investigated on the aspect of their response to Pb toxicity in the presence or absence of EDTA addition. After 8 d’s Pb treatment, root length, root surface area and root volume of E. splendens decreased much more than those of E. argyi, and reduced considerably with increase of Pb, while no marked change was noted for root average diameter. Compared to E. argyi, length of root with diameter (D)<0.2 mm was significantly reduced for E. splendens as Pb increased. D<0.1 mm E. splendens root had cross-sectional surface area at Pb≥10 mg/L, while for E. argyi, it was at Pb≥25 mg/L. With increase of Pb, DW of E. splendens decreased much more than that of E. argyi. E. argyi exhibited much more tolerance to Pb toxicity than E. splendens. Treatment with 100 mg/L Pb plus 50 mmol/L EDTA significantly decreased the length and surface area of D≤0.2 mm root, increased the length and surface area of 0.2≤D≤0.8 mm root for the case of E. argyi, while for E. splendens, length and surface area of D<0.6 mm root reduced, as compared to 100 mg/L Pb treatment, alone. At 100 mg/L Pb, shoot Pb accumulation in E. splendens and E. argyi were 27.9 and 89.0 μg/plant DW respectively, and much more Pb was uptaken by the root and translocated to the stem of E. argyi as compared to E. splendens. Treatment of the plant with 100 mg/L Pb plus 50 mmol/L EDTA increased leaf Pb accumulation from 16.8 to 84.9 g/plant for E.splendens and from 18.8 to 52.5 g/plant for E. argyi, while both root and stem Pb pronouncedly reduced for both Elsholtzia species. The increased translocation of Pb to the leaf of E. splendens being than that of E. argyi after treatment with 100 mg/L Pb plus 50 mmol/L EDTA should be further investigated.

Soil Heavy Metal Pollution Around the Dabaoshan Mine,Guangdong Province,China

Soil contamination in the vicinity of the Dabaoshan Mine, Guangdong Province, China, was studied through determi- nation of total concentrations and chemical speciation of the toxic metals, Cu, Zn, Cd, and Pb, using inductively coupled plasma mass spectrometry. The results showed that over the past decades, the environmental pollution was caused by a combination of Cu, Zn, Cd, and Pb, with tailings and acid mine drainage being the main pollution sources affecting soils. Significantly higher levels （P ≤ 0.05） of Cu, Zn, Cd, and Pb were found in the tailings as compared with paddy, garden, and control soils, with averages of 1486, 2516, 6.42, and 429 mg kg^-1, respectively. These metals were continuously dispersed downstream from the tallings and waste waters, and therefore their concentrations in the paddy soils were as high as 567, 1 140, 2.48, and 191 mg kg^-1, respectively, being significantly higher （P ≤ 0.05） as compared with those in the garden soils. The results of sequential extraction of the above metals from all the soil types showed that the residual fraction was the dominant form. However, the amounts of metals that were bound to Fe-Mn oxides and organic matter were relatively higher than those bound to carbonates or those that existed in exchangeable forms. As metals could be transformed from an inert state to an active state, the potential environmental risk due to these metals would increase with time.

Chemical Species of Aluminum Ions in Acid Soils *1

Soil samples collected from several acid soils in Guangdong, Fujian, Zhejiang and Anhui provinces of the southern China were employed to characterize the chemical species of aluminum ions in the soils. The proportion of monomeric inorganic Al to total Al in soil solution was in the range of 19% to 70%, that of monomeric organic Al (Al OM) to total Al ranged from 7.7% to 69%, and that of the acid soluble Al to total Al was generally smaller and was lower than 20% in most of the acid soils studied. The Al OM concentration in soil solution was positively correlated with the content of dissolved organic carbon (DOC) and also affected by the concentration of Al 3+ . The complexes of aluminum with fluoride (Al F) were the predominant forms of inorganic Al, and the proportion of Al F complexes to total inorganic Al increased with pH. Under strongly acid condition, Al 3+ was also a major form of inorganic Al, and the proportion of Al 3+ to total inorganic Al decreased with increasing pH. The proportions of Al OH and Al SO 4 complexes to total inorganic Al were small and were not larger than 10% in the most acid soils. The concentration of inorganic Al in solution depended largely on pH and the concentration of total F in soil solution. The concentrations of Al OM, Al 3+ ,Al F and Al OH complexes in topsoil were higher than those in subsoil and decreased with the increase in soil depth. The chemical species of aluminum ions were influenced by pH. The concentrations of Al OM, Al 3+ , Al F complexes and Al OH complexes decreased with the increase in pH.

Distribution of Chemical Forms for Co, Cr, Ni and V in Typical Soils of China

Co, Ni, Cr and V in 25 typical soils of China were fractionated into exchangeable, carbonate bound (calcareous soils), Mn oxide bound, organically bound, amorphous Fe oxide bound, crystalline Fe oxide bound and residual forms using a seven-step sequential extraction procedure, so as to study the distribution of chemical forms of these metals as well as the effects of soil properties on the distribution. The results showed that most of soil Co, Ni, Cr and V were present in residual forms, and the distribution ratio averaged 48.2% for Co, 53.0% for Ni, 81.5% for Cr and 68.7% for V. The speciation of heavy metals was greatly influenced by soil physico-chemical properties and the chemistry of elements. The results also indicated that the recovery of metal elements by the sequential extraction procedure was satisfactory, with the relative difference between the sum of seven forms and the total content in soils averaging 9.5% for Co, 12.8% for Ni, 6.6% for Cr and 7.2% for V.

Integration of SEM/WDX elemental mapping and micromorphology to determine mineralogical traits of peat soils(case study：Northern Iran)

We explored the potential use of combining wavelength-dispersive X-ray spectroscopy(WDX) and micromorphology of thin sections to identify minerals in peat soils. Peat soil minerals from three peats and swamps across Golestan Province in northern Iran were first characterized by micromorphological studies. Soils were composed mainly of quartz, muscovite, biotite, pyroxene,sericitized Fe-nodules, and iron-rich garnet. In addition,micromorphological results indicated that Galougah Coastal Swamp sections contained some inorganic residue with biological origin including oyster and limpet, which may be related to the swamp's location near Gorgan Gulf.In order to determine mineralogical properties of samples,twelve unknown grains were chosen for elemental concentration map studies. Quartz, garnet, ilmenite, calcite,and pyroxene in Suteh samples; epidote and Fe-nodule in Ghaleh-Ghafeh Peat Swamp; and barite, phyllosilicates,and calcite in Galougah were identified by WDX mapping of Si, Al, Fe, Ca, Mg, C, Ba, S, and Ti. Composition of the oysters' body was also analyzed by WDX for Si, Ca, Fe,and C. The results indicated that most of the minerals in all sections likely formed through weathering, inheriting their composition from the parent rock. This research suggests that merging micromorphology and SEM/WDX image techniques can be useful in confirming the presence of mineral particles in soil science.

Sequential Extraction of Aluminum and Iron from Acidic Soils by Chemical Selective Dissolution Methods

Potassium chloride, Na-pyrophosphate, CuCl2, NH4-oxalate, dithionite-citrate-bicarbonate (DCB) and Na-citrate solutions were employed to extract aluminum (Al) and iron (Fe) sequentially and separately from 15 acidic soils located at the Mangshan Mountains, Hunan Province, China. Many evidences showed that separate pyrophosphate extracted mainly KCI-extractable Al, organo-Al complexes and some inorganic Al compounds, whereas separate CuCl2 extracted KCl-extractable Al and some organo-Al complexes. CuCl2 extracted much less amounts of Al than pyrophosphate did from the soils. Separate oxalate did not extract all KCl-Pyrophosphate- CuCl2 -oxalate sequentially extractable Al and Fe. Also, separate DCB did not extract all KCl- pyrophosphate- CuCl2 -oxalate- DCB sequentially extractable Al. The forms of Al extracted by oxalate and DCB from the soils were majorly noncrystalline. The interlayered materials of 1.4-nm intergrade minerals of the soils were attributed mainly to hydroxy Al polymers.