Intermittent Growth of a Newly-Born Volcanic Island and Its Feeding System Revealed by Geological and Geochemical Monitoring 2013–2020, Nishinoshima, Ogasawara, Japan

The island-forming Nishinoshima eruptions in the Ogasawara Islands, Japan, provide a rare opportunity to examine how the terrestrial part of Earth’s surface increases via volcanism. Here, the sequence of recent eruptive activity of Nishinoshima is described based on long-term geological and geochemical monitoring of eruptive products. Processes of island growth and temporal changes in the magma chemistry are discussed. The growth of Nishinoshima was sustained by the effusion of low-viscosity andesite lava flows since 2013. The lava flows spread radially with numerous branches, resulting in compound lava flows. Lava flows form the coherent base of the new volcanic edifice; however, pyroclastic eruptions further developed the subaerial volcanic edifice. The duration of three consecutive eruptive episodes decreased from 2 years to a week through the entire eruptive sequence, with a decreasing eruptive volume and discharge rate through time. However, the latest, fourth episode was the most intense and largest, with a magma discharge rate on the order of 106 m3/day. The temporal change in the chemical composition of the magma indicates that more mafic magma was involved in the later episodes. The initial andesite magma with ∼60 wt% SiO2 changed to basaltic andesite magma with ∼55 wt% SiO2, including olivine phenocryst, during the last episode. The eruptive behavior and geochemical characteristics suggest that the 2013–2020 Nishinoshima eruption was fueled by magma resulting from the mixing of silicic and mafic components in a shallow reservoir and by magma episodically supplied from deeper reservoirs. The lava effusion and the occasional explosive eruptions, sustained by the discharge of magma caused by the interactions of these multiple magma reservoirs at different depths, contributed to the formation and growth of the new Nishinoshima volcanic island since 2013. Comparisons with several examples of island-forming eruptions in shallow seas indicate that a long-lasting voluminous lava effusion with a discharge rate on the order of at least 104 m3/day (annual average) to 105 m3/day (monthly average) is required for the formation and growth of a new volcanic island with a diameter on km-scale that can survive sea-wave erosion over the years.

Geochemical Monitoring of Formation Fluids for Reservoir Management Considering Complicating Factors in Mature Oilfields

At the present stage of the hydrocarbon production process, most of the unique and largest fields in the world are at a late stage of development. Despite the active development and policy of a decarbonised economy, the demand for liquid and gaseous hydrocarbons remains high, while of inevitably growing the number of mature fields. The Volga-Ural oil and gas province today is an old oil and gas producing region, most of the fields have already entered the final stage of development. However, through the introduction and development of new technologies for oil extraction, monitoring of production and localization of reserves, the life of the fields can be extended. One of these technologies is geochemical monitoring of well production. Its goal is to optimize the development of mature fields on the basis of promptly obtained information about the state of the wells using geochemical studies of the formation fluid, allowing timely implementation of the necessary measures. Geochemical studies allow identifying the source of fluid entering the well, determining a violation in the wellbore structure, checking the tightness of downhole equipment for separate operation, and performing an area analysis of the area development efficiency. This type of research is relevant both in giant fields with a large stock of production wells, often characterized from a geological point of view by multilayer structure, with technological complexity, packing, wear of equipment and strings, in some cases the impossibility of running gauge for research, and in fields with low depletion. The possibilities of geochemistry for solving local operational problems in wells are shown. Several hydrogeological complexes have been studied, the change in the properties of the produced water during the development process is described. The concepts of the geochemical conditions in the hydrocarbon deposits that existed earlier are changing due to the development of these objects as a dynamic system, continuous injection of different types of water into the reservoir, the use of enhanced oil recovery methods and other technogenic impact associated with the development of reserves. The digital revolution and the modern development of the industry marked the beginning of the creation of the Digital Atlas of Groundwater, the development of specialized algorithms that allow processing large amounts of data.

Insights into Particle-Bound Metal(loid)s in Winter Snow Cover: Geochemical Monitoring of the Korkinsky Coal Mine Area, South Ural Region, Russia

Snow plays an important role in air quality and winter geochemical monitoring in the South Ural region. This study deals with the air pollution monitoring of particle-bound metal(loid) concentrations using snow cover around the deepest coal mine in Eurasia, the Korkinsky coal mine. We studied the concentrations and ratios of suspended and dissolved forms of metal(loid)s (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sb, Sr, and Zn) in snow samples. We examined 56 snow cover samples, collected at 12 sites located north, south, east and west of the Korkinsky coal mine. All snow samples were taken in January 2020. The spectral reflectance curves, cluster analysis, and spatial distribution maps were used to evaluate the potential sources of PM-bound metal(loid)s and the potential relationship among them. The highest concentrations (μg/L) were reported for Fe, Al, and Zn. In addition to the mine influence, burning coal for residential heating was identified as the major anthropogenic metal(loid) source. It was shown that elevated concentrations of some trace metals in snow samples were associated with southerly winds and the location of spoil heaps.

Geochemical monitoring of deionized seawater injected underground during construction of an LPG rock cavern in Namikata, Japan, for the safety water curtain system

An underground liquified petroleum gas (LPG) storage facility was constructed between 1998 and 2006 in Namikata, Imabari City, Ehime Prefecture, Japan, to increase domestic LPG stockpiles. The most important issue during construction and operation of this facility is gas leakage prevention. To thwart water leakage, the water curtain system was constructed according to design standards, and a large amount of deionized seawater (seal water) was continuously injected into the rock mass around the cavern to keep the water level constant during both construction and operation. It is possible to distinguish three end member waters (existing groundwater, seawater or fossil seawater, and seal water) using the salinity and isotope (δ18O) difference because seal water injected underground has almost the same δ18O value as seawater. In this study, continuous observation is carried out using the geochemical techniques for flow analysis with a mixing ratio of three end members in the initial construction period (April 2005 to March 2006) of the LPG underground storage facility. It is determined that existing groundwater and seawater originally distributed in this region are partly replaced by seal water in the cavern.

Discontinuous Geochemical Monitoring of the Galleria Italia Circumneutral Waters (Former Hg-Mining Area of Abbadia San Salvatore, Tuscany, Central Italy) Feeding the Fosso Della Chiusa Creek

The Galleria Italia waters drain the complex tunnel system of the former Hg-mining area of Abbadia San Salvatore (Tuscany, central Italia) and feed the 2.5 km-long Fosso della Chiusa creek. The mining exploitation was active for more than one century and more than 100,000 tons of liquid mercury were produced by roasting processes of cinnabar (HgS). In this work, a discontinuous geochemical monitoring of the Galleria Italia circumneutral waters was carried out from February 2009 to October 2020, during which the main physicochemical parameters, main and minor dissolved species and trace elements (including Hg) were determined. In the observation period, significant variations in the water chemistry were recorded, particularly when flooding waves, due to intense precipitations, occurred, with the two main events being recorded in February 2009 and January 2010. The chemical composition of the Galleria Italia waters was Ca(Mg)-SO4 and related to congruent dissolution of gypsum/anhydrite at which a contribution from carbonatic and silicatic minerals and partial solubilization of CO2 and and H2S oxidation is to be added. Regarding the trace elements, Al, Mn and Fe were up to 1500, 768 and 39520 μg L−1, with these elements also showing high contents in the sediment precipitating by the Galleria Italia waters. In most cases, dissolved mercury was below the instrumental detection limit (<0.1 μg L−1), although occasionally it reached >1 μg L−1. Considering a mean flow rate of 40 L s−1 of the discharged water, the amount of dissolved mercury released from Galleria Italia was computed, although most mercury was occurring in the sediment (1.2 mg kg−1). A more realistic computation of mercury released from Galleria Italia should involve a sampling network along the Fosso della Chiusa before entering the riverine system of the Tiber basin, into which dissolved and suspended mercury are to be determined along with that occurring in the sediments.