Changes in lead and zinc lability during weathering-induced acidification of desert mine tailings: Coupling chemical and micro-scale analyses     

Sarah M. Hayes  Scott A. White  Thomas L. Thompson  Raina M. Maier  Jon Chorover 《Applied Geochemistry》2009

Desert mine tailings may accumulate toxic metals in the near surface centimeters because of low water through-flux rates. Along with other constraints, metal toxicity precludes natural plant colonization even over decadal time scales. Since unconsolidated particles can be subjected to transport by wind and water erosion, potentially resulting in direct human and ecosystem exposure, there is a need to know how the lability and form of metals change in the tailings weathering environment. A combination of chemical extractions, X-ray diffraction, micro-X-ray fluorescence spectroscopy, and micro-Raman spectroscopy were employed to study Pb and Zn contamination in surficial arid mine tailings from the Arizona Klondyke State Superfund Site. Initial site characterization indicated a wide range in pH (2.5–8.0) in the surficial tailings pile. Ligand-promoted (DTPA) extractions, used to assess plant-available metal pools, showed decreasing available Zn and Mn with progressive tailings acidification. Aluminum shows the inverse trend, and Pb and Fe show more complex pH dependence. Since the tailings derive from a common source and parent mineralogy, it is presumed that variations in pH and “bio-available” metal concentrations result from associated variation in particle–scale geochemistry. Four sub-samples, ranging in pH from 2.6 to 5.4, were subjected to further characterization to elucidate micro-scale controls on metal mobility. With acidification, total Pb (ranging from 5 to 13 g kg⁻¹) was increasingly associated with Fe and S in plumbojarosite aggregates. For Zn, both total (0.4–6 g kg⁻¹) and labile fractions decreased with decreasing pH. Zinc was found to be primarily associated with the secondary Mn phases manjiroite and chalcophanite. The results suggest that progressive tailings acidification diminishes the overall lability of the total Pb and Zn pools.  相似文献   

The statistical properties of immiscible fluid displacement in bond/site correlated network models of porous media     

R. Maier  W. G. Laidlaw 《Mathematical Geology》1991,23(1):87-110

A statistical formulation is introduced which allows the determination of capillary pressure and relative permeability curves from lattice properties and, by extension, possibly core properties. Comparisons of statistical results to simulation results generally show good agreement for both drainage and imbibition. These processes turn out to be two different formulations of a single problem in one view presented here. Both agreement and disagreement between statistics and simulation results provide insight into the characteristics of the flow of immiscible fluids in porous media. A considerable amount of topological information on the fluids is also obtainable by these methods.  相似文献   

Aperçu sur les amas sulfurés massifs des hercynides Marocaines     

A. J. Bernard  O. W. Maier  A. Mellal 《Mineralium Deposita》1988,23(2):104-114

Massive sulfide deposits located on Hercynian islets of northwestern Morocco exhibit four main characteristics:

They are strata-bound massive pyrrhotite deposits mined for sulfur and/or base metals occasionally occurring as sulfides of workable grade.

Volcanic rocks with which these massive sulfide orebodies are associated are scarce, although always present as acid flows of submarine emissions of either rhyolitic or more often quartz-keratophyric nature. Later on, basic plutonics intruded the pelitic country rocks.

Stockworks underlying the massive sulfide orebodies are common, but not systematic. When present, they occur in siltite ± phyllite ± carbonate rocks at the wall of massive sulfide lenses. They consist of fissural disseminations transformed by epimetamorphic recrystallization and by one schistosity generally concordant with s₀.

Associated alterites and exhalites belong to three types, i.e., sericitite (or biotite-rich rock), chloritite, and/or chert (jasper).

Generally well located in a back-arc basin environment characterized by a two-phase geological history, i.e., “extension and volcanism, compression and metamorphism”, these volcano-sedimentary deposits exhibit distal features with regard to the volcanism coeval with their sedimentation. They are mostly linked with strongly reducing environmental properties entailing pyrrhotite and/or magnetite syngenetic deposition, whatever the iron activity.  相似文献   

Using a decadal diatom sediment trap record to unravel seasonal processes important for the formation of the sedimentary diatom signal     

Dominique Béatrice Maier  Veronika Gälman  Ingemar Renberg  Christian Bigler 《Journal of Paleolimnology》2018,60(2):133-152

Sediment trap studies and high frequency monitoring are of great importance to develop a deeper understanding of how seasonal environmental processes are imprinted in sediment signal formation. We collected whole year diatom assemblages from 2002 to 2014 with a sequential sediment trap from a varved boreal lake (Nylandssjön, Sweden) together with environmental and limnological parameters, and compared them with the corresponding diatom record of the annual laminated sediment. Our data set indicates a large year-to-year variability of diatom succession and abundance patterns, which is well reflected in the varved sediments. Specifically, Cyclotella glomerata dominated the annual sediment trap record (as well as in the corresponding sediment varves) in years with warmer air temperatures in March/April, and Asterionella formosa dominated the annual sediment assemblages as a consequence of years characterized by higher runoff before lake over-turn. Years succeeding forest clearance in the lake catchment showed marked increase in diatom and sediment flux. The DCA scores of the yearly diatom trap assemblages clearly resemble the lake’s thermal structure, which indicates that the relative abundance of major taxa seems primarily controlled by the timing of seasonal environmental events, such as above-average winter air temperature and/or autumn runoff and the current thermal structure of the lake. The high seasonal variability between environmental drivers in combination with the physical limnology leaves us with several possible scenarios leading to either an A. formosa versus C. glomerata dominated annual diatom sediment signal. With this study we highlight that short-term environmental events and seasonal limnological conditions are of major importance for interpreting annual sediment signals.  相似文献   

Catchments as reactors: a comprehensive approach for water fluxes and solute turnover   总被引：1，自引：1，他引：0  

Peter Grathwohl  Hermann Rügner  Thomas Wöhling  Karsten Osenbrück  Marc Schwientek  Sebastian Gayler  Ute Wollschläger  Benny Selle  Marion Pause  Jens-Olaf Delfs  Matthias Grzeschik  Ulrich Weller  Martin Ivanov  Olaf A. Cirpka  Ulrich Maier  Bertram Kuch  Wolfgang Nowak  Volker Wulfmeyer  Kirsten Warrach-Sagi  Thilo Streck  Sabine Attinger  Lars Bilke  Peter Dietrich  Jan H. Fleckenstein  Thomas Kalbacher  Olaf Kolditz  Karsten Rink  Luis Samaniego  Hans-Jörg Vogel  Ulrike Werban  Georg Teutsch 《Environmental Earth Sciences》2013,69(2):317-333

Sustainable water quality management requires a profound understanding of water fluxes (precipitation, run-off, recharge, etc.) and solute turnover such as retention, reaction, transformation, etc. at the catchment or landscape scale. The Water and Earth System Science competence cluster (WESS, http://www.wess.info/) aims at a holistic analysis of the water cycle coupled to reactive solute transport, including soil–plant–atmosphere and groundwater–surface water interactions. To facilitate exploring the impact of land-use and climate changes on water cycling and water quality, special emphasis is placed on feedbacks between the atmosphere, the land surface, and the subsurface. A major challenge lies in bridging the scales in monitoring and modeling of surface/subsurface versus atmospheric processes. The field work follows the approach of contrasting catchments, i.e. neighboring watersheds with different land use or similar watersheds with different climate. This paper introduces the featured catchments and explains methodologies of WESS by selected examples.  相似文献   

Variations in annual snowline and area of an ice-covered stratovolcano in the Cordillera Ampato,Peru, using remote sensing data (1986–2014)     

Bijeesh Kozhikkodan Veettil  Ulisses Franz Bremer  Sergio Florêncio de Souza  Éder Leandro Bayer Maier  Jefferson Cardia Simões 《国际地球制图》2016,31(5):544-556

This research focuses on the recent variations in the annual snowline and the total glaciated area of the Nevado Coropuna in the Cordillera Ampato, Peru. Maximum snowline altitude towards the end of dry season is taken as a representative of the equilibrium line altitude of the year, which is an indirect measurement of the annual mass balance. We used Landsat and IRS LISS3 images during the last 30 years due to its better temporal coverage of the study site. It is found that there was a decrease of 26.92% of the glaciated area during 1986–2014. We calculated the anomalies in precipitation and temperature in this region and also tried to correlate the changes in glacier parameters with the combined influence of El Niño – Southern Oscillation (ENSO) and pacific decadal oscillation (PDO). It is concluded that the snowline of Nevado Coropuna has been fluctuated during ENSO, and maximum fluctuations were observed when ENSO and PDO were in phase.  相似文献   

Gradients controlling natural attenuation of ammonium   总被引：1，自引：0，他引：1  

Uli Maier  Hermann Rügner  Peter Grathwohl 《Applied Geochemistry》2007,22(12):2606

Oxidation of reduced pollutants such as in groundwater often takes place at steep redox gradients where oxygenated water is being mixed into polluted water such as landfill leachate. In order to identify controlling parameters and quantify the influence of environmental factors for degradation, sensitivity analysis was performed by means of scenario specific numerical modelling. Geometrical factors such as aquifer thickness have been shown to be very influential on the capability of natural attenuation of pollutants in groundwater. The scenarios investigated here include biodegradation at redox gradients in groundwater, so called fringe processes, for (i) a partly contaminated aquifer with two reaction fronts, (ii) and a spatially variable aquifer thickness. In addition, (iii) the influence of groundwater recharge and (iv) restricted supply of O₂ to contaminated water by slow dispersion and diffusion across the capillary fringe are investigated. Contaminated aquifer thickness, zones of enhanced mixing due to flow focussing and diffusion/dispersion coefficients in the capillary fringe are identified qualitatively as controlling factors for natural attenuation under complex conditions, whereas predictive functions will require further research.  相似文献   

Boundary element elastic analysis of layered soils by a successive stiffness method     

G. Maier  G. Novati 《国际地质力学数值与分析法杂志》1987,11(5):435-447

The elastostatic analysis of layered systems (such as a soil consisting of a set of L individually homogeneous strata) is tackled here on the basis of discretized boundary integral equations (boundary element method). By exploiting the peculiar chain-like pattern of the system, a recursive formula is obtained which generates economically a ‘stiffness matrix’ of the first n layers (from bottom) at the upper interface with the subsequent layer (n = 1…L). The ‘successive stiffness’ method proposed is shown to imply noteworthy advantages with respect to both the standard boundary element method by zones (or subregions) and another ad hoc, earlier method resting on a boundary element approach combined with the transfer matrix concept. This conclusion is corroborated by two-dimensional examples.  相似文献   

The upper atmosphere as a regulator of subauroral red arcs     

S. ChandraE.J. Maier 《Planetary and Space Science》1972

The mechanisms for producing a subauroral red arc (SARARC) are studied by solving a system of basic ionospheric and atmospheric equations. It is shown that many of the observed features of a SARARC can be explained within the framework of the two processes generally responsible for the ionospheric behavior during a magnetic storm: these are (1) energy conduction from the magnetosphere to the ionosphere and (2) the changes in neutral composition of the lower atmosphere caused by the increase in turbulent mixing. Both the processes trigger a complex chain of events which ultimately results in the redistribution of both the charged and neutral particles, an increase in the electron, ion, and neutral temperatures, and a decrease in the electron density in the altitude region near the F2 peak. It is shown that both the occurrence and the emission intensity of a SARARC are regulated by the neutral atmosphere, even though conduction of the thermal energy from the magnetosphere to the ionosphere provides the excitation energy fo the optical remission. Recent satellite measurements of the ionospheric parameters have confirmed the validity of these findings and have provided grounds for rejecting several other theories which have been proposed in the literature.  相似文献   

Low abundance of the dinoflagellates,Pfiesteria piscicida, P. shumwayae, andCryptoperidiniopsis spp., in South Carolina tidal creeks and open estuaries     

Alan J. Lewitus  Kenneth C. Hayes  Bonnie M. Willis  JoAnn M. Burkholder  Howard B. Glasgow  A. Fred Holland  Philip P. Maier  Parke A. Rublee  Robert Magnien 《Estuaries and Coasts》2002,25(4):586-597

The toxicPfiesteria complex are a group of dinoflagellates that have received considerable attention in recent years as causative factors in fish kill or lesion events in North Carolina estuaries and in the Pocomoke River of Chesapeake Bay. In response to the potentialPfiesteria threat, the South Carolina Task Group on Harmful Algae was formed in late 1997 and implemented programs to monitor harmful algal blooms and respond to fish kills or lesion events with particular emphasis on the Bushy Park (Cooper River, Charleston) region, a site of annually recurrent menhaden lesion events.Pfiesteria piscicida, Pfiesteria shumwayae, andCryptoperidiniopsis spp. were documented in South Carolina estuaries. Routine monitoring and fish kill or lesion event sampling consistently indicated low abundances compared to estimates from similar programs in North Carolina and Maryland that sampled areas with a history ofPfiesteria toxic activity. The finding thatPfiesteria-like organism (PLO) abundances were always low in samples collected during menhaden lesion events in Bushy Park suggested other causes for lesion progression, althoughPfiesteria spp. could not be ruled out as a factor in lesion initiation. Based on the previously demonstrated positive relationship between PLO abundance, chlorophylla, and inorganic nutrient concentrations (in laboratory experiments and North Carolina field observations), we hypothesized that the relatively low abundance ofPfiesteria spp. and other PLO (e.g.,Cryptoperidiniopsis) in South Carolina estuaries is related to the relatively low supply of phytoplankton prey, as supported by interstate comparisons in chlorophylla concentrations. Nitrate concentrations were generally much lower in South Carolina estuaries. Estuarine eutrophication may be an important consideration in explaining interstate differences in susceptibility toPfiesteria-related toxic events.  相似文献