Long-term bed load transport rate based on aerial-photo and ground penetrating radar surveys of fan-delta growth, Coast Mountains, British Columbia

Sequential aerial photography, sonar bathymetry, ground-penetrating radar (GPR), and sediment sampling and analysis provide the basis for calculating the volumetric and mass rate of progradation of the delta of Fitzsimmons Creek, a steep, high-energy, debris-flow-dominated channel draining about 100 km² of the southern Coast Mountains of British Columbia. Fitzsimmons Creek is typical of small mountain rivers in the region. GPR imaging is used to define the pre-depositional morphology of the receiving basin, a technique that improves the accuracy of the volumetric survey. The 52-year record (1947–1999) of progradation yielded an average annual volumetric transport rate of 1.00±0.16×10⁴ m³ year⁻¹ for bed load, corresponding to a mass transport rate of 1.60±0.28×10⁴ Mg year⁻¹. Bed load yields are consistent with those obtained in hydrogeomorphically similar basins in the region and elsewhere. Decade-based annual rates, which vary from 0.64±0.11×10⁴ to 2.85±0.38×10⁴ Mg year⁻¹, provide poor estimates of the 52-year average. Indeed, the 52-year record may also not be long enough to fully integrate the significant fluctuations in the sediment efflux from Fitzsimmons Creek. The methodology proposed in this paper can be transferred to other comparable mountain environments worldwide.     

Extraction and recovery of precious metals from electronic waste printed circuit boards by bioleaching acidophilic fungi

Printed circuit boards contain precious metals. They are produced in large volumes, rendering them an important component of the electronic waste. In view of the heterogeneity of the metals present, reprocessing of electronic waste is a heinous task. The present study focused on leaching of valuable metals from electronic waste printed circuit boards using Aspergillus niger DDNS1. The adaptation phases began at 0.1, 0.5 and 1.0% of fine powder of printed circuit boards with 10% inoculum and were optimized with three effective factors, viz. initial pH, particle size and pulp density, to achieve the maximum simultaneous recovery of the valuable metals. The interactions of these metals were also deciphered using scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectrum and atomic absorption spectroscopy. The results indicated that extraction of the precious metals was accomplished mainly through the unique organic acids originating from A. niger DDNS1. The initial pH played an important role in the extraction of the precious metals and the metals precipitate formation. The leaching rate of the metals was generally higher at low powder dosage of printed circuit boards. The toxicity of the printed circuit boards had little effect on two-step bioleaching at the pulp density of 0.1% compared to one-step bioleaching. The two-step bioleaching process was followed under organic acid-forming conditions for the maximum mobilization of metals. Thus, the precious metals from printed circuit boards could be mobilized through fungal bioleaching which promises an important industrial application in recycling of electronic wastes.     

Rare earth elements in the clay fraction of coaliferous sediments of the Arkagalinskoe (Magadan district) and Dolinskoe (Sakhalin Island) coalfields

The study of REE distribution in the clay fraction of sedimentary rocks from two coalfields made it possible to distinguish several types of REE distribution, which correlate with their mineral composition. It is shown that the REE fractionation was related to the mineral reconstruction of the primary clay fraction and some detrital minerals in the course of postsedimentary transformations of rocks during diagenesis, early catagenesis, and beginning of late catagenesis. These transformations were governed by several factors, such as the composition of sediments; hydrochemical features of accumulation environment; the chemical composition, dynamics, and feeding sources of pore solutions; the porosity and permeability of sediments and rocks; and the content of organic matter and its reaction ability.     

Investigation of submicron volcanic aerosol-particles by photoelectron emission

Volcanic aerosol emissions have been studied for the first time by in situ photoelectric charging. Explorative studies on Mt Etna reveal large concentrations of particles below 1000 nm with the spectrum peaking in the size range of 100–1000 nm diameter. Although a large fraction of the particles is already charged upon emission, the net electrical charge carried by the aerosol turned out to be close to zero.Particles with high photoelectric yield vary greatly in their relative abundance and seem to occur mainly at active points of the volcano.     

Authigenic iron and titanium oxides in triassic red beds: (St. Bees Sandstone), Cumbria,Northern England

Authigenic iron and titanium oxides occur in three main textural varieties in the St. Bees Sandstone, a Triassic red bed succession in Cumbria. These are: (a) overgrowths of haematite, titaniferous haematite, anatase, and rutile which generally occur on detrital host grains of similar compositions. The overgrowths may occur as syntaxial rim cements or rhombohedral and prismatic projections and are always in optical continuity, (b) discrete crystals of anatase (including octahedrite) and haematite 10-40 μm in size occur in pore spaces, and (c) fine grained ( < 1 μm) pigmentary haematite occurs as grain coatings around detrital grains and in the interstitial matrix. The euhedral nature and pore-filling habit clearly indicate the authigenic origin of these iron- and titanium oxides. All three textural varieties are believed to have been precipitated from ground waters containing dissolved ferrous and titanium ions. These ions were derived from the intrastratal solution of detrital iron and titanium bearing grains including ferromagnesian silicates and iron-titanium oxides. The precipitation of iron oxides from migrating ground waters in the manner described here goes some way to explaining how thick, uniformly red successions can be formed.