Ge/Si Ratio of River Water in the Yarlung Tsangpo: Implications for Hydrothermal Input and Chemical Weathering

Germanium/Silicon (Ge/Si) ratio is a common proxy for primary mineral dissolution and secondary clay formation yet could be affected by hydrothermal and anthropogenic activities. To decipher the main controls of riverine Ge/Si ratios and evaluate the validity of the Ge/Si ratio as a weathering proxy in the Tibetan Plateau, a detailed study was presented on Ge/Si ratios in the Yarlung Tsangpo River, southern Tibetan Plateau. River water and hydrothermal water were collected across different climatic and tectonic zones, with altitudes ranging from 800 m to 5000 m. The correlations between TDS (total dissolved solids) and the Ge/Si ratio and Si and Ge concentrations of river water, combined with the spatial and temporal variations of the Ge/Si ratio, indicate that the contribution of hydrothermal water significantly affects the Ge/Si ratio of the Yarlung Tsangpo River water, especially in the upper and middle reaches. Based on the mass balance calculation, a significant amount of Ge (11–88%) has been lost during its transportation from hydrothermal water to the river system; these could result from the incorporation of Ge on/into clays, iron hydroxide, and sulfate mineral. In comparison, due to the hydrothermal input, the average Ge/Si ratio in the Yarlung Tsangpo River is a magnitude order higher than the majority of rivers over the world. Therefore, evaluation of the contribution of hydrothermal sources should be considered when using the Ge/Si ratio to trace silicate weathering in rivers around the Tibetan Plateau.

Synthesis of Silver Nanoparticles by Hydrothermal Processing

Hydrothermal water treatments of silver acetate (CH3COOAg) were investigated to reveal the factors controlling the formation of silver nanoparticles (AgNPs) with uniform size distribution. The effects of reaction time and concentration of silver acetate solution on the synthesis of Ag nanoparticles were studied, and the fabricated products were characterized. The hydrothermal water treatments of CH3COOAg were carried out between the temperatures of 250 - 450 °C in a batch reactor. In supercritical water regions, at 400 °C and a pressure of 31.5 MPa, silver particles are rapidly synthesized due to reaction rate increases at a low dielectric constant of supercritical water. The preparation of the silver particles with 30-80 nm in size showed a highly crystalline structure identified by XRD and TEM observations.

Hydrothermal Water Enabling One-Pot Transformation of Amines to Alcohols

While the amination of primary alcohols to amines is quite normal, the reverse reaction, deamination of amines to alcohols is rare. Recent advances achieve the transformation by catalytic multistep processes. We report a one-pot method that enables water nucleophilic attack of amines through the unique catalytic role of hydrothermal water. By achieving dehydrogenation of amines or building targeting group, we fulfilled amines transformation by subsequent reduction or direct deamination, which could further link to the utilization of naturally abundant glutamic acid. The method avoids oxidants, catalysts or multistep, thus achieves simple, green and selective transformation of primary amines.

Hydrothermal Water Enabling One-Pot Transformation of Amines to Alcohols

While the amination of primary alcohols to amines is quite normal, the reverse reaction, deamination of amines to alcohols is rare. Recent advances achieve the transformation by catalytic multistep processes. We report a one-pot method that enables water nucleophilic attack of amines through the unique catalytic role of hydrothermal water. By achieving dehydrogenation of amines or building targeting group, we fulfilled amines transformation by subsequent reduction or direct deamination, which could further link to the utilization of naturally abundant glutamic acid. The method avoids oxidants, catalysts or multistep, thus achieves simple, green and selective transformation of primary amines.

Exploring the Kamchatka Geothermal Region in the Context of Life’s Beginning

This article is a brief review of research in the Kamchatka geothermal region initiated by David Deamer and the author in 1999. Results obtained over the last 20 years are described, including a seminal experiment in which biologically important organic compounds were dispersed in a hot spring to determine their fate. Other investigations include ionic and organic composition of hydrothermal water, the source of hydrothermally generated oil, and pressure–temperature oscillations in hydrothermal systems. The relation of these results to research on the origin of life is discussed.

Influence of hydrous pyrolysis on distribution of carbon and hydrogen isotopes by organic matter fractions. The nature of oil generation in the calder of Uzone Volcano in Kamchatka

The process of oil seeps transformation from the Uzon volcano caldera under the influence of hydrous pyrolysis at a temperature of 350 °C in argon and oxygen was investigated. It is shown that carbon and hydrogen isotope type curves (ITC) reflect the processes occurring in organic matter during hydrous pyrolysis in oxidizing and neutral media. The similarity in forms between carbon ITC of the Uzon oil seeps, the Bogachevka oil and biota of hydrothermal sources is revealed. Hydrogen ITCs have a more complex form, apparently associated with exchange processes occurring in hydrothermal water. Based on the conducted studies, it was assumed that on the one hand oil seeps in the Uzon caldera can serve as a source for the formation of Bogachevka oil, and on the other hand, it is possible that the circulating hydrothermal water in the caldera of the Uzon volcano brings to the surface the organic matter of the Bogachevka oil formation.