Studies of shallow-water hydrothermal vents have been lagging behind their deep-sea counterparts. Hence, the importance of these systems and their contribution to the local and regional diversity and biogeochemistry is unclear. This study analyzes the bacterial community along a transect at the shallow-water hydrothermal vent system of Milos island, Greece. The abundance and biomass of the prok...

It is generally assumed that the hydrothermal stability of organically modified silica networks is promoted by high monomer connectivity, network flexibility, and the presence of hydrophobic groups in the network. In this study a range of organosilica compositions is synthesized to explore the extent to which these factors play a role in the hydrothermal dissolution of these materials. Composit...

Ž . Previous research on sea floor Fe III oxyhydroxide deposits has focused primarily on deep-sea, hydrothermal systems found along volcanically active portions of the mid-ocean ridges and on hydrogenetic deposits formed in deep basins and along continental shelves. There is, however, not much known about their formation in shallow-water settings associated with volcanic islands. The hydrotherm...

The diversity of many marine benthic groups is unlike that of most other taxa. Rather than declining from the tropics to the poles, much of the benthos shows high diversity in the Southern Ocean. Moreover, many species are unique to the Antarctic region. Recent work has shown that this is also true of the communities of Antarctic deep-sea hydrothermal vents. Vent ecosystems have been documented...

Hydrothermal systems have prevailed throughout geological history on earth, and ancient ARCHAEAN hydrothermal deposits could provide clues to understanding earth's earliest biosphere. Modern hydrothermal systems support a plethora of microorganisms and macroorganisms, and provide good comparisons for paleontological interpretation of ancient hydrothermal systems. However, all of the microfossil...

In the past few decades, chemosynthetic ecosystems at deep-sea hydrothermal vents have received attention as plausible analogues to the early ecosystems of Earth, as well as to extraterrestrial ecosystems. These ecosystems are sustained by chemical energy obtained from inorganic redox substances (e.g., H2S, CO2, H2, CH4, and O2) in hydrothermal fluids and ambient seawater. The chemical and isot...

In experiments modeling volcanic or hydrothermal settings amino acids were converted into their peptides by use of coprecipitated (Ni,Fe)S and CO in conjunction with H2S (or CH3SH) as a catalyst and condensation agent at 100 degreesC and pH 7 to 10 under anaerobic, aqueous conditions. These results demonstrate that amino acids can be activated under geochemically relevant conditions. They suppo...

Impacts are common geologic features on the terrestrial planets throughout the solar system, and on at least Earth and Mars impacts have induced hydrothermal convection. Impact-generated hydrothermal systems have been suggested to possess the same life supporting capability as hydrothermal systems associated with volcanic activity. However, evidence of fossil microbial colonization in impact-ge...

We describe how seafloor heat flow is determined, review current understanding of advective heat loss from oceanic lithosphere, and present results from three field areas to illustrate how heat flow measurements are used (along with complementary data) to resolve fluid flow rates and patterns. Conductive heat flow through much of the seafloor is lower than predicted by lithospheric cooling mode...

Hydrothermal processes on Mars: It has been suggested that hydrothermal process may have been active in the history of Mars[1]. This concept is supported by three lines of evidences: (1) widespread evidences of volcanic activity on Mars; (2) high levels of WEH (water-equivalent-hydrogen) found in two large equatorial regions on Mars (ODY_NS) [2]; (3) The ground ice excavated by meteorite impact...