Geochemistry of rare earth elements in a marine influenced coal and its organic solvent extracts from the Antaibao mining district, Shanxi, China

Twenty-six samples including roof, bottom and coal plies of a marine influenced coal bed were collected from the Antaibao mining district, Shanxi, China. The rare earth elements (REEs) were determined in solids and organic solvent extracts. The distribution pattern showed three distinct patterns: shale-like, LREE-rich and HREE-rich. This is attributed to the variable microenvironment of peat-forming swamp, the degree of marine influences and different REE sources. REEs in the coal are mainly controlled by detrital minerals but also affected by seawater. The chondrite-normalized REE patterns of the organic solvent extracts are distinctly different from those of corresponding original coal samples, which show a negative Eu anomaly, a depletion of middle REEs and an enrichment of HREEs. The LREEs in coal extracts are likely adsorbed by hydrogen-containing functional groups, and HREEs are likely bonded to carbon atoms.     

A review of: “Finite-difference techniques for vectorized fluid dynamics calculations”

Abstract

Edited by D. L. Book. Springer-Verlag, New York, 1981. 226 pp., DM 72,—, $33.60. (ISBN 0 387 104828)     

Report on the 4th International Meeting of the IUGS Lower Cretaceous Ammonite Working Group, the “Kilian Group” (Dijon, France, 30th August 2010)

The 4th Kilian Group meeting (Dijon, France, 30th August 2010) focused on the Aptian and Albian Stages. For the Aptian, a two-fold division of the stage was adopted for the Mediterranean area with a boundary between the Dufrenoyia furcata and Epicheloniceras martini Zones. The main changes to the zonal scheme concern the Lower Aptian with: the introduction of a Deshayesites luppovi Subzone in the upper part of the Deshayesites oglanlensis Zone; the replacement of Deshayesites weissi by Deshayesites forbesi as new index-species of the second interval zone; the introduction of a Roloboceras hambrovi Subzone in the upper part of the D. forbesi Zone; and the subdivision of the D. furcata Zone into the D. furcata and Dufrenoyia dufrenoyi Subzones. For the Albian, the upper part of the Douvilleiceras mammillatum Zone (Lower Albian) is now characterized by a Lyelliceras pseudolyelli Subzone. The main amendments concern the Upper Albian. The base of this substage is defined by the base of the Dipoloceras cristatum Zone. Above it, the Upper Albian zonal scheme comprises in stratigraphic order the Mortoniceras pricei, Mortoniceras inflatum, Mortoniceras fallax, Mortoniceras rostratum, Mortoniceras perinflatum and Arrhaphoceras briacensis Zones.     

The Uncertainty in the True End Point of a Fossil's Stratigraphic Range When Stratigraphic Sections Are Sampled Discretely

Stratigraphic sections are often sampled at well-defined discrete points. Because of the incompleteness of the fossil record, a particular species may not be observed even when it is extant at a sampling point. We introduce a model and Bayesian analysis for estimating the true time of disappearance of a lineage from a section in the face of the possibility that failure to find the species beyond its observed stratigraphic range may represent false negatives. We incorporate proper prior information, including an estimated longevity of the species and the probability that it will be observed if extant. Our analysis produces a posterior density for the true extinction time of the species. Summaries of this probability distribution provide a point estimate of the extinction time, a standard deviation for the uncertainty in the estimate, and confidence intervals for the time of extinction. We apply our model to stratigraphic ranges of benthic foraminifera collected from the early Late Cretaceous (Cenomanian and Turonian) from Eastbourne, England.     

Mineralogy and environmental stability of slags from the Tsumeb smelter,Namibia

Three types of smelting slags originating from historically different smelting technologies in the Tsumeb area (Namibia) were studied: (i) slags from processing of carbonate/oxide ore in a Cu–Pb smelter (1907–1948), (ii) slags from Cu and Pb smelting of sulphide ores (1963–1970) and (iii) granulated Cu smelting slags (1980–2000). Bulk chemical analyses of slags were combined with detailed mineralogical investigation using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM/EDS) and electron microprobe (EPMA). The slags are significantly enriched in metals and metalloids: Pb (0.97–18.4 wt.%), Cu (0.49–12.2 wt.%), Zn (2.82–12.09 wt.%), Cd (12–6940 mg/kg), As (930–75,870 mg/kg) and Sb (67–2175 mg/kg). Slags from the oldest technology are composed of primary Ca- and Pb-bearing feldspars, spinels, complex Cu–Fe and Cu–Cr oxides, delafossite–mcconnellite phases and Ca–Pb arsenates. The presence of arsenates indicates that these slags underwent long-term alteration. More recent slags are composed of high-temperature phases: Ca–Fe alumosilicates (olivine, melilite), Pb- and Zn-rich glass, spinel oxides and small sulphide/metallic inclusions embedded in glass. XRD and SEM/EDS were used to study secondary alteration products developed on the surface of slags exposed for decades to weathering on the dumps. Highly soluble complex Cu–Pb–(Ca) arsenates (bayldonite, lammerite, olivenite, lavendulan) associated with litharge and hydrocerussite were detected. To determine the mineralogical and geochemical parameters governing the release of inorganic contaminants from slags, two standardized short-term batch leaching tests (European norm EN 12457 and USEPA TCLP), coupled with speciation-solubility modelling using PHREEQC-2 were performed. Arsenic in the leachate exceeded the EU regulatory limit for hazardous waste materials (2.5 mg/L). The toxicity limits defined by USEPA for the TCLP test were exceeded for Cd, Pb and As. The PHREEQC-2 calculation predicted that complex arsenates are the most important solubility controls for metals and metalloids. Furthermore, these phases can readily dissolve during the rainy season (October to March) and flush significant amounts of As, Pb and Cu into the environment in the vicinity of slag dumps.     

Characterization of sediments in an abandoned mining area; a case study of Mansfeld region,Germany

The distribution of selected heavy metals, including some radionuclides, metalloids and non-metals was determined in stream sediments in a region influenced by abandoned copper mining and ore processing activities. A considerable amount of the ore processing waste with a very complex composition and highly elevated concentrations of zinc, sulfur, lead, copper, arsenic, and a lot of other elements in the range between 100 and 1,000 mg/kg (Sb, Mn, Ni, Cr, Cd, Hg, and Ag) was piled up on mine dumps. The dispersion of the pollutants originating from this source and their environmental impact were investigated. Both, sediments and original waste material were studied to indicate the pathways and the mobilization behavior of different pollutants. For this purpose, the process of the elution of pollutants by application of different fractionation schemes was studied. The capabilities of different analytical techniques are shown for the analysis of solid samples (X-ray fluorescence spectrometry, Gamma-spectrometry) and liquid ones (ICP-atomic emission spectrometry, ICP-mass spectrometry and different techniques of atomic absorption). Additionally, the coupling of ion chromatography and ICP-MS detection was used to study the distribution of arsenic species in the sediment cores of a lake which acts as a natural sink for the region.     

Radium and barium at GEOSECS stations in the Atlantic and Pacific

²²⁶Ra and Ba show a general linear correlation in the oceanic water column within the uncertainties of the data: the slope of the line is about 4.6 nanomoles (nmoles) Ra/mole Ba, the intercept being at about 4 nmoles Ba/kg. This demonstrates the usefulness of Ba as a “chemical analogue” of Ra. Box-model calculations indicate that the average deep-water excess of Ra over Ba should be about 10% relative to the surface. This is consistent with the observations outside the deep northeast Pacific. However, the uncertainties in the data are such that the regional variation in the primary input cannot be resolved. In the deep waters of the North Pacific there is in fact a large excess of Ra relative to Ba. The one detailed profile presently available (204) can be explained consistently by a simple vertical advection-diffusion model.