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. 相似文献
Spring water samples of the Harz Mountains were taken in several seasons of 2010, 2011, and 2012. The samples have been analysed for main components (Na+, K+, Ca2+, Mg2+, SO42−, Cl−, HCO3− and NO3−), trace elements (Fe, Cu, Pb, Zn, Y and REE), DOC, δ18O and δ2H of water. Meteoric water is indicated as the main source of the springs sampled. High precipitation rates lead to a dilution of the measured elemental concentrations. Furthermore, regional differences of rock and water interactions were found. REE concentrations and patterns of the spring waters vary between the distinct geological units and reflect the geochemical characteristics of the surrounding rocks. The actual data compared to measured data from the seventies and nineties of the last century indicate a decrease of the sulphate concentrations in the spring waters which is typical of many European mountain catchments. 相似文献
The main task is to estimate the qualitative and quantitative contribution of urban territories and precisely of the process
of urbanization to the Global Carbon Cycle (GCC). Note that, on the contrary to many investigations that have considered direct
anthropogenic emission of CO2(urbanized territories produce ca. 96–98% of it), we are interested in more subtle, and up until the present time, weaker
processes associated with the conversion of the surrounding natural ecosystems and landscapes into urban lands. Such conversion
inevitably takes place when cities are sprawling and additional "natural" lands are becoming "urbanized". 相似文献
High-Mg chloritoid (XMg = 0·40–0·47) andrelatively high-Mg staurolite (XMg = 0·25–0·28)coexisting with kyanite and garnet were identified in a mica–garnet-richrock associated with very high-pressure eclogites in the BugheaComplex of the Leaota Massif (South Carpathians). Major andtrace element geochemical data for both fresh eclogites andassociated rocks which represent a metasomatic or retrogradealteration rind of the eclogites, indicate a pelitic precursor.Magnesian chloritoid was found as inclusions in garnet as partof a chloritoid–kyanite–garnet assemblage whichis indicative of high-pressure conditions. The host garnet showsa typically prograde chemical zoning pattern. The chloritoid-bearingassemblage is confined to the inner part of the garnet porphyroblasts,whereas the matrix assemblage in equilibrium with Mg-rich garnetrims has exceeded the thermal stability limit of chloritoid.Pressure–temperature pseudosections for simplified compositionsapproaching the rock bulk-chemistry show a high-pressure fieldfor the identified chloritoid-bearing assemblage in good agreementwith pressure–temperature estimates in the CFMASH andKCFMASH chemical subsystems using analysed mineral compositions.The derived pressure–temperature path is clockwise, indicatingoverprinting during exhumation from 1·8 GPa and 580°Cto 1·15 GPa and 620°C, at a water activity approachingaH2O = 1. These conditions were attained in a subduction mélangeindicating transient thermal perturbations of a subduction channel. KEY WORDS: high-pressure metapelite; Mg-rich chloritoid; P–T path; P–T pseudosection; very high-pressure eclogite相似文献
Blueschist was recently recognized within the Lhasa terrane, which is one of the NE Gondwana blocks. In this rock, the Mn and Mg contents of garnet enclosing aegirine-rich clinopyroxene, rutile and quartz decrease and increase, respectively, from core to rim. Amphibole changes from glaucophane through Na–Ca amphibole to Ca amphibole. The Si contents of phengite are high in the centre but low along the rim. The P – T path, starting above 2.5 GPa–450 °C and showing subsequently first a temperature increase to 500 °C and then a pressure release via blueschist conditions to 0.6 GPa, was reconstructed using a P – T pseudosection calculated for the P – T range 0.4–2.8 GPa and 250–650 °C. This path points to deep subduction of a cold oceanic crust probably beneath the NE Gondwana margin during Permo-Triassic times. This finding contributes to a better understanding of the pre-Cenozoic history of major terranes of NE Gondwana. 相似文献
at temperatures between 400 and 700°C. The ultrapotassic fluid appearing at pressures above 15 kbar on the low-temperature sides of the corresponding reaction curves, which show positive dP/dT slopes, is probably supercritical. The P-T positions of the reactions are compatible with KMASH mineral reactions studied previously and with melting investigations in the KMASH system undertaken at temperatures higher than 700°C.
It is possible that natural rocks, chiefly K-rich metasediments subducted as minor portions of the oceanic crust, could give rise to low-temperature ultrapotassic fluids, mainly at temperatures between 300° to 600°C and pressures between 15 and 30 kbar. The ascending K-rich fluids would penetrate the overlying mantle to metasomatize it. After termination of the subduction process, heating of this mantle material, previously cooled by the subducted lithosphere, could lead to the formation of high-temperature K-rich magmas. 相似文献
New petrologic and 40Ar/39Ar geochronologic data constrain conditions of Alpine metamorphism along the northwestern border of the Tauern Window. The
P-T estimations based on phengite barometry were determined for samples from units of the Lower Austroalpine nappe complex exposed
above the Southpenninic interior of the Tauern Window, and from upper parts of the Southpenninic “Bündner Schiefer” sequence.
Results suggest that both Mesozoic metasedimentary nappe units (Reckner and Hippold Nappes) and an ophiolitic nappe (Reckner
Complex) of the Lower Austroalpine nappe complex have been metamorphosed at pressures between 8 and 10.5 kbar and temperatures
around 350 °C. The structurally highest Lower Austroalpine unit (Quartzphyllite Nappe) was not affected by high-pressure metamorphism
and records maximum P-T conditions of approximately 4 kbar and 400 °C. Highest parts of the structurally underlying Southpenninic Bündner Schiefer
sequence were metamorphosed at intermediate pressures (6–7 kbar). Temperatures increased in all structural units during decompression.
Whole-rock 40Ar/39Ar plateau ages of silicic phyllites and cherts with abundant high-Si phengites record ages around 50 Ma in the Reckner Nappe,
and 44–37 Ma in the Hippold Nappe and Southpenninic Bündner Schiefer sequence. These ages are interpreted to date closely
the high-pressure metamorphism.
The Lower Austroalpine-Southpenninic border area in the NW Tauern Window appears to have evolved along an indented, fragmented
active continental margin where the Reckner Complex represents one of the oldest sections of the Southpenninic (Piemontais)
Oceanic tract that was originally situated close to, or even within, the Lower Austroalpine continent. During closure of the
Piemontais Ocean, the resultant subduction zone did not entrain components of the Reckner Complex or its cover sequences (Reckner
and Hippold Nappes): therefore “Eoalpine” high-pressure metamorphism did not occur. Sequences exposed within the study area
were subducted to relatively shallow depths during the last stage of consumption of oceanic crust and immediately prior to
final continental collision.
Received: 30 July 1996 / Accepted: 7 April 1997 相似文献