虹吸排渗系统在尾矿坝降水工程中的应用

为保证尾矿坝加高工程的顺利实施，采用虹吸排渗系统来降低坝体内部的浸润线高度。以马兰庄铁矿尾矿库为例，对尾矿库工程中虹吸排渗系统的组成和尾矿砂中虹吸井的施工方法进行了简要介绍。虹吸井设置在初期坝上游附近，相对下游高差为8m。虹吸井深12～16m，直径550mm，相邻井点的间距均为6m。虹吸管为DN57型PVC软管。现场完成了14口虹吸井，并进行了13组双井抽水试验和一组单井抽水试验。其结果表明，采用清水冲击钻进方法施工的虹吸井成井质量较好。虹吸井的涌水量可达147m^3/d。虹吸系统在井内水深小于6．5m时可自动工作。监测结果表明，在虹吸系统投入使用后，坝体地下水位埋深普遍在坡面7m以下。虹吸系统自行启动性能较强，降水效果明显，完全可以适应加高工程的需要。     

Seasonal changes in iron transport and nature of dissolved organic matter in a humic river in northern Finland

Changes in the concentration of iron and dissolved organic matter (DOM), and in the colour and fluorescence properties in the River Kiiminkijoki were investigated as functions of the seasonal flow regime over a two-year period. The iron concentration in filtrates and the ratio of Fe to DOC in the river increased under low flow conditions and decreased during the flood periods. The colour of the dissolved organic matter increased with increasing iron content, the effect being more pronounced during the warm period of the year than in winter. The ratio of fluorescence to DOC increased during the warm period of the year but not in winter, and decreased rapidly with discharge at the beginning of the flood period in autumn. The results give indications of the origin, formation, nature, and fate of the DOM in the river water. Temperature-dependent microbiological processes in the formation and sedimentation of iron-organic colloids seem to be important. Estimates are given for the amounts and transport rates of iron discharged into the Gulf of Bothnia by the river.     

广西田林龙车乡陨铁的初步研究

本文对广西田林龙车乡陨铁熔壳、比重、硬度、矿物成分及化学成分进行了研究。通过光片镜下观察、电子显微镜、电子探针、穆斯堡尔谱、X-射线衍射、化学分析等测试手段,发现该陨铁主要由铁纹石、镍纹石、合纹石等组成,其次含少量磷铁镍矿,磁铁矿等。铁纹石呈板状,镍纹石呈条带状相间排列形成明显的维斯台登构造,属中粗粒八面体铁陨石。 用扫描电镜在陨铁的松散颗粒中发现较好的矿物雏晶,这是比较少见的。     

Variable190Os/184Os ratio in acid residues of iron meteorites

In residual materials obtained on dissolution of iron meteorites in 2M H₂SO₄, the ratio of¹⁹⁰Os/¹⁸⁴Os has been measured by radiochemical neutron activation analysis. Most residues have a normal isotopic ratio (to within ±2%). However, in some residues both positive and negative deviations in the isotopic ratio are seen. The most spectacular deviations are in the insoluble fragments (nuggets) from Sikhote Alin iron meteorite where the¹⁹⁰Os/¹⁸⁴Os ratio is about 50% of the normal value. The new results confirm our earlier observations that iron meteorites contain pre-solar grains.     

Iron speciation in interaction with organic matter: Modelling and experimental approach

The present study aims to model iron speciation when interacting with natural organic matter. Experimental data for iron speciation were achieved with insolubilized humic acid as an organic matter analogue for 1.8 × 10^− 3 M and 1.8 × 10^− 4 M iron concentrations and 2–5 pH range. Combining EPR spectroscopy and chemical analysis allowed us to fit NICA-Donnan model parameters for both organic complexation of iron and oxides precipitation.     

Iron–phosphorus relationship in the iron and phosphorite ores of Egypt

Iron and phosphorite ores are very common in the geological record of Egypt and exploitable for economic purposes. In some cases these deposits belong together to the same geographic and geologic setting. The most common deposits include phosphorites, glauconites, and iron ores. Phosphorites are widely distributed as a belt in the central and southern part of Egypt. Sedimentary iron ores include oolitic ironstone of Aswan area and karstified iron ore of Bahria Oasis. Glauconites occur in the Western Desert associated with phosphorites and iron ores. As these ores are exploitable and phosphorus in iron ores and iron in phosphorites are considered as gangue elements, the iron–phosphorus relationship is examined in these deposits to clarify their modes of occurrences and genetic relationship based on previously published results.Phosphorus occurs mainly as carbonate fluorapatite (francolite). Iron, on the other hand, occurs in different mineralogical forms such as glauconites, hematite, limonite and goethite.In P-rich rocks (phosphorites) no relationship is observed between iron and phosphorus, which in turn indicates that the FeP model is unlikely to interpret the origin of the late Cretaceous phosphorites and the association of phosphorites and glauconites in Egypt. In Fe-rich rocks (iron ores and glauconites) also no relationship between iron and phosphorus is observed. The present work, therefore, does not support the hypothesis that there is a genetic relationship between phosphorus and iron in sedimentary rocks.     

Arsenic in the groundwater of Ouro Preto (Brazil): its temporal behavior as influenced by the hydric regime and hydrogeology

In the city of Ouro Preto (MG), water catchment for public supply originates from superficial drainage, springs, old abandoned mines and some driven wells. In the rocks of the region, As is originally found in gold-enriched sulphide-bearing mineral deposits. The weathering process introduces As into the hydrological system by dissolution of this element into the leachate. Measurement of the As content in the groundwater of some catchments was carried out during 1 year and these measurements demonstrated high As content—up to 224 μg L⁻¹ of As(V)—during the rainy season (the maximum concentration limit according to World Health Organization is 10 μg L⁻¹). Lower values were observed during the dry season and in some sampling stations, As was not even detected. The As concentration variability during 1 year shows a strict and direct relationship to seasonal and hydrological conditions. For city authorities, responsible for public water supply, it is necessary to perform a complete inventory of the water sources used and constantly monitor the As content in the water.     

Spectral properties, iron oxide content and provenance of Namib dune sands

This paper applies multispectral remote sensing techniques to map the Fe-oxide content over the entire Namib sand sea. Spectrometric analysis is applied to field samples to identify the reflectance properties of the dune sands which enable remotely sensed Fe-oxide mapping. The results indicate that the pattern of dune colour in the Namib sand sea arises from the mixing of at least two distinct sources of sand; a red component of high Fe-oxide content (present as a coating on the sand grains) which derives from the inland regions, particularly from major embayments into the Southern African escarpment; and a yellow coastal component of low Fe-oxide content which is brought into the area by northward-moving aeolian transport processes. These major provenances are separated by a mixing zone between 20 km and 90 km from the coast throughout the entire length of the sand sea. Previous workers have also recognised a third, fluvial, provenance, but the methodology applied here is not able to map this source as a distinct spectral component.