Element budgets of pine stands on lignite and pyrite containing mine soils

To analyze the development of pine ecosystems on lignite and pyrite containing mine soils, four pine stands with ages of 3–35 years were investigated in a chronosequence approach. Bulk precipitation, throughfall and soil solution in depths of 20, 40, 70 and 100 cm were studied over a three-year period to determine element fluxes in these forest ecosystems on extreme acidic and saline soils.Element budgets are controlled by the processes induced by pyrite oxidation such as intensive weathering of primary minerals, precipitation and leaching of secondary phases.Despite low water fluxes, element outputs can reach extraordinary high values due to very high concentrations in the soil solution. Although element outputs decrease drastically with stand age, respectively, site age, they exceed those of comparable pine stands on non-mine sites. Nitrogen release from the lignite fraction represents a special characteristic of the examined substrates. Nitrogen losses beneath the rooted zone can be 34 kg N ha⁻¹ yr⁻¹ in 100 cm depth. Element input and output in the examined ecosystems are far from balance. Closed cycling of nutrients seems to be recognizable in the case of potassium.     

Geochemistry of ice-covered, meromictic Lake A in the Canadian High Arctic

The geochemical processes occurring within meromictic Lake A (maxdepth 120 m) on northern Ellesmere Island, Canada, were investigated to determinethe history of the lake and to provide a baseline for future studies. The lake contained seawaterdiluted by freshwater input that had been mixed prior to the lake's isolation from tidalaction. Input of freshwater after isolation of the lake created vertical stratification resultingin the creation of distinct oxic, suboxic and anoxic zones. Dissolved oxygen was present to 13 m,and sulphide beneath 32 m. Manganese and iron cycling dominated the redox chemistrybetween these depths. Total manganese concentrations reached 176 M, higher thanin most other natural stratified lake or marine environments.     

Natural Gas Hazard (CO2, 222 Rn) within a Quiescent Volcanic Region and Its Relations with Tectonics: The Case of the Ciampino-Marino Area, Alban Hills Volcano, Italy

Groundwater surveys were performed by detailed(around 300 sites) grid-analysis of water temperature, pH, redox potential, electrical conductivity, ²²²Rn, alkalinity and by calculating the pCO₂, throughout the Ciampino and Marino towns in the Alban Hills quiescent volcano (Central Italy). Following several episodes of dangerous CO₂ exhalation from soils during the last 20 years and earlier ashistorically recorded, the work aimed at assessing the Natural Gas Hazard (NGH) including the indoor-Rn hazard. The NGH was defined as the probability of an area to become a site of poisonous peri-volcanic gas exhalations from soils to the lower atmosphere (comprising buildings). CO₂ was found to be a ``carrier' for the other poisonous minor and in trace components (H<sub>s</sub>S, CH<sub>4</sub>, <sup>222</sup>Rn, etc.). This assessment was performed by extrapolating in the aquifer CO<sub>2</sub> and <sup>222</sup>Rn conditions, and discriminating sectors where future CO<sub>2</sub> flux in soils as well as indoor-Rn measurements have to be noted. A preliminary indoor-Rn survey was performed at about 200 sites. The highest values were found in the highest pCO<sub>2</sub> and high <sup>222</sup>Rn values in groundwater. This indicates convection and enhanced permeability in certain sectors of the main aquifer, i.e., along the bordering faults and inside the gas-trap of the Ciampino Horst., where ``continuous gas-phase micro-macro seepage mechanism' is invoked to explain the high peri-volcanic gases flux.     

A double-head photon-counting photometer for fast timing observations

The structure of the electronics of the two-head, high-speed photometer operating on the 152-cm G.D. Cassini telescope of Bologna University has been fully redesigned for high-time-resolution observations of fast variable sources, in particular, of the optical counterparts of X-ray binary systems. The fast photometer now permits sampling times from 0.1 ms to 100 s. The handling of the system clock and I/O configuration have been modified to provide rigorous synchronization of the sampling time with an external high-stability clock and the continuous acquisition of an uninterrupted data stream. The continuous data-acquisition process, which is driven by an external clock, is limited only by the capacity of the hard disk and is supported by a double-buffer SRAM memory designed to overcome any discontinuity in the asynchronous communication with the computer. Real-time monitoring of the data enables continuous evaluation of the weather conditions, and the directly displayed light curve can be used to determine the optimal management of the observations.     

Proterozoic copper deposits in NW Queensland,Australia: Sulfur isotopic data

Sulfur isotopic disequilibrium is commonly observed between associated pyrite and copper sulfides in NW Queensland. A sulfur isotopic study of copper mineralization in dolomites at Paradise Valley and arenites at Mammoth has allowed the significance of such disequilibrium to be evaluated. Copper mineralization at Paradise Valley is characterized by a greater enrichment in ³⁴S, with δ³⁴S values often greater than +30‰, for both copper sulfides and associated syngenetic/diagneetic pyrite. At Mammoth, copper sulfides have isotopic compositions (δ³⁴S=?15.9 to ?0.3‰) transitional between disseminated syngenetic/diagenetic pyrite (δ³⁴S=?5.7 to ?1.7‰) and epigenetic vein pyrite (δ³⁴S=?17.9 to ?7.1‰) suggesting progressive reaction and replacement of syngenetic/diagenetic pyrite by a copper-bearing mineralizing fluid under oxidizing conditions. The isotopic data, within the constraints imposed by geological and geochemical factors, support a model of reaction between copper-bearing mineralizing fluids and pre-existing syngenetic/diagenetic pyrite for both the carbonate- and arenite-hosted deposits.     

Trace metals and radionuclides reveal sediment sources and accumulation rates in Jordan Cove, Connecticut

Many small estuaries are influenced by flow restrictions resulting from transportation rights-of-way and other causes. The biogeochemical functioning and history of such systems can be evaluated through study of their sediments. Ten long and six short cores were collected from the length of Jordan Cove, Connecticut, a Long Island Sound subestuary, and analyzed for stratigraphy, radionuclides (¹⁴C, ²¹⁰Pb, ²²⁶Ra, ¹³⁷Cs, and ⁶⁰Co), and metals (Ag, Cd, Cu, Pb, Zn, Fe, and Al). For at least 3,800 yr, rising sea level has gradually inundated Jordan Cove, filling it with mud similar to that currently being deposited there. Long-term sediment accumulation in the cove averaged close to 0.1 cm yr⁻¹ over the last three millennia. Recent sediment accumulation rates decrease inland from 0.84 cm yr⁻¹ to 0.40 cm yr⁻¹, and are slightly faster than relative sea-level rise at this site (0.3 cm yr⁻¹). Similarity of depth distributions of trace metals was used to confirm relative sediment accumulation rates. ⁶⁰Co and Ag are derived from sources outside the cove and its watershed, presumably the Millstone nuclear power plant and regional contaminated sediments, respectively. The combined data suggest that Long Island Sound is an important source of sediment to the cove; a minor part of total sediment is supplied from the local watershed. Trace metal levels are strongly correlated with Fe but not with either organic matter or Al. Sediment quality has declined in the cove over the past 60 yr, but only slightly. Cu, Pb, and Zn data correlate strongly with Fe but not with either organic matter or aluminum. Ratios of Ag to Fe and to trace metals suggest that Ag in the cove is derived almost entirely from Long Island Sound. This result supports the notion that Fenormalized Ag can serve as a better tracer of some kinds of contamination than more common and abundant metals, like Cu, Pb, and Zn. *** DIRECT SUPPORT *** A01BY085 00008     

Evaluation of the potential for gas leakage along wellbores in the St. Lawrence Lowlands basin,Quebec, Canada

Wellbore attributes (i.e., deviation, casings and plugging characteristics) for 85 wells in the St. Lawrence Lowlands basin of southern Quebec were compiled from drilling reports and abandonment programs to provide an overview of the abandoned well characteristics and to establish a diagnosis on the long-term reliability of the completion and abandonment practices carried out by the companies since the beginning of oil and gas exploration. Using these data, the conventional and unconventional wells were divided into four categories: (1) conventional wells drilled before 1950, (2) conventional wells drilled between 1950 and 1970, (3) conventional wells drilled after 1970 and shale gas wells (all drilled after 2000). Very little information was available for wells drilled before 1950. More information was available for the wells drilled from 1950 to 1970 which is considered a transition period between old and modern technology. Conventional and unconventional wells drilled after 1970 were generally well documented and their attributes corresponded to API standards. A decision tree, inspired from the methodology proposed by Watson and Bachu (SPE Drill Complet 24(1):115–126, 2009.  https://doi.org/10.2118/106817-PA), was then created to assess the potential of leakage of each of the conventional and unconventional wells using the compiled attributes. The factors defining the probability of well leakage were wellbore deviation, height of cement in casing annuli (partially or fully cemented), type of abandonment plugs (cement or mechanical plugs) and drilling date (before or after 1970). Among the 85 wells assessed by this tree, the probability of leakage was higher than 50% for 55 wells (65% of wells). Wellbore deviation and lack of information on the construction and abandonment methods were respectively the primary and secondary causes of high probability of leakage of these wells.     

<Superscript>230</Superscript>Th/U Chronology and Geochemistry of Irinovskoe Hydrothermal Field (Mid-Atlantic Ridge)

The results of ²³⁰Th/U dating and mineralogical–geochemical studies of sulfide ores from the Irinovskoe hydrothermal field and the Severo-Zapadnoe ore occurrence (Mid-Atlantic Ridge) are presented. Sulfides are represented primarily by copper–sulfide ores with 12–30% Cu content; sulfur- and zinc-sulfide ores are distributed less frequently. The analysis of a change in the composition of sulfides over time has made it possible to identify three stages of formation. Each stage assumes that mineral associations are changed from high-temperature (sulfur and copper sulfide) to medium temperature (Zn–Cu and Zn-sulfide) sulfide ores. The whole age range of formation of the hydrothermal deposits falls within the time interval of about 58000–8000 for the Irinovskoe field and 69000–11000 years ago for the Severo-Zapadnoe ore occurrence.     

Depositional setting,provenance, and tectonic-volcanic setting of Eocene–Recent deep-sea sediments of the oceanic Izu–Bonin forearc,northwest Pacific (IODP Expedition 352)

New biostratigraphical, geochemical, and magnetic evidence is synthesized with IODP Expedition 352 shipboard results to understand the sedimentary and tectono-magmatic development of the Izu–Bonin outer forearc region. The oceanic basement of the Izu–Bonin forearc was created by supra-subduction zone seafloor spreading during early Eocene (c. 50–51 Ma). Seafloor spreading created an irregular seafloor topography on which talus locally accumulated. Oxide-rich sediments accumulated above the igneous basement by mixing of hydrothermal and pelagic sediment. Basaltic volcanism was followed by a hiatus of up to 15 million years as a result of topographic isolation or sediment bypassing. Variably tuffaceous deep-sea sediments were deposited during Oligocene to early Miocene and from mid-Miocene to Pleistocene. The sediments ponded into extensional fault-controlled basins, whereas condensed sediments accumulated on a local basement high. Oligocene nannofossil ooze accumulated together with felsic tuff that was mainly derived from the nearby Izu–Bonin arc. Accumulation of radiolarian-bearing mud, silty clay, and hydrogenous metal oxides beneath the carbonate compensation depth (CCD) characterized the early Miocene, followed by middle Miocene–Pleistocene increased carbonate preservation, deepened CCD and tephra input from both the oceanic Izu–Bonin arc and the continental margin Honshu arc. The Izu–Bonin forearc basement formed in a near-equatorial setting, with late Mesozoic arc remnants to the west. Subduction-initiation magmatism is likely to have taken place near a pre-existing continent–oceanic crust boundary. The Izu–Bonin arc migrated northward and clockwise to collide with Honshu by early Miocene, strongly influencing regional sedimentation.     

Crustal melting and recycling: geochronology and sources of Variscan syn-kinematic anatectic granitoids of the Tormes Dome (Central Iberian Zone). A U–Pb LA-ICP-MS study

International Journal of Earth Sciences - In this study, we report U–Pb Laser Ablation ICP-MS zircon and ID-TIMS monazite ages for peraluminous granitoid plutons...