构树对菱镁矿区破损土地的生态适应性

[目的]研究菱镁矿粉尘对土壤理化性质的影响以及构树对镁粉尘污染土壤的耐受性.[方法]采用盆栽试验,室内模拟氧化镁粉尘沉降、人工掺和废矿堆.[结果]当镁粉尘施加量小于10％时,促进构树生长,当土壤镁含量为4.17 g/kg时,构树单株生物量达3.46g,明显大于洁净土壤的生物量（2.81 g）;构树对生长土质的要求低,土壤中矿石含量25％时,生物量最大为6.12g,明显比洁净土壤生物量高出3.31 g;施加镁粉尘明显改变了构树生长土壤的理化性质,pH由6.78升到9.48,电导率先增加到651.8 μS/cm后降至375.7 μS/cm,速效磷含量从52.1 mg/kg降至16.9 mg/kg,全镁含量从1.403 g/kg升至9.015 g/kg.[结论]构树对镁具有较强耐受能力,并对生长土质要求低,在不同程度破损土质中均能健康生长,在修复菱镁矿区镁污染土地方面具有相当大的潜力.     

Sedimentary and diagenetic features in saline lake deposits of the Monegros region, northern Spain

The Monegros region in northern Spain is marked by the occurrence of a large number of ephemeral to dry lake basins, occupying small karstic depressions. The lacustrine sediment fill of these basins contain various carbonate and silicate minerals whose origin and palaeoenvironmental significance is poorly understood. For the present study, 14 lake basins were sampled in order to establish vertical, lateral and regional variations in mineralogical and textural characteristics, aimed at determining the mode of formation of the various mineral phases present. In nearly all basins, the same sequence of three lithological units is recognized, including a basal clayey unit, a middle magnesite-bearing and gypsum-rich unit, and a calcite- and dolomite-dominated surface unit. Distribution patterns of carbonate minerals indicate that magnesite is a synsedimentary precipitate, dolomite formed as a diagenetic authigenic phase, and calcite is partly authigenic and partly allogenic. All clay minerals, including sepiolite and smectite, appear to be allogenic. Regional variations are marked by similarities between groups of neighbouring basins, but no overall trend related to regional drainage patterns is recognized. The middle lithological unit records a lake stage with predominantly chemical sedimentation (Unit II), overlying a less well documented interval corresponding to a perennial lake stage with lower salinity (Unit III), whereas the surface unit formed during a period with predominantly clastic sedimentation. Based on a comparison with other regional records, the middle unit is attributed to an Early Holocene humid stage, separated from the overlying Late Holocene deposits by a hiatus that corresponds to a Mid Holocene arid stage.     

Mycorrhizal status of plant species colonizing a magnesite mine spoil in India

Summary The present study reports the vesicular arbuscular mycorrhizal fungal association with 14 plant species colonizing a magnesite mine spoil in Salem, Tamil Nadu state, India. The soil was poor in Olsen-available P (5–45 kg/ha^-1). Hyphal, arbuscular and vesicular infection was noticed. Infection ranged from 32 to 82%. Thirteen VAM fungal species were identified. Spores of Glomus fasciculatum and Gigaspora gigantea were commonly found in the magnesite mine spoil.     

菱镁混凝土夹芯板抗弯性能试验研究

针对菱镁混凝土夹芯板抗弯性能开展试验研究,初步探讨其受弯构件的基本力学性能,并对其破坏特征、变形曲线、开裂荷载和极限荷载进行了分析。结果表明:夹芯板从开裂到最终破坏具有明显的变形,延性较好;板材在加载过程中,在支座处率先出现剪切裂缝,随后在跨中侧面上出现起鼓现象;板的极限承载能力和刚度相对较低,由于人工制作,造成同批次夹芯板存在强度差异。所得结果可为该类夹芯板后续研究提供依据,同时可供有关工程设计人员参考。     

Removal of cadmium from aqueous solution by a soil containing magnesite

Removal of Cd (II) from aqueous solution by a soil containing magnesite and thermal activated soil containing magnesite was investigated. Maximum activation temperature was determined at 700°C for 2?h and maximum adsorption capacities were determined as 4.20?mg/g for natural magnesite, 38.91?mg/g for thermal activated magnesite at 25°C respectively. Equilibrium contact time of cadmium was determined for 2?h. Adsorption of Cd (II) on soil containing magnesite conforms to Langmuir's isotherm.