Distribution and transformation of Fe and Mn in hydrothermal plumes and sediments and the potential function of microbiocoenoses

Abstract

The spatial separation of suspended Fe and Mn in plumes, recorded at Mid-Atlantic Ridge (MAR) sites, some regions on the East Pacific Rise (EPR) and in the western Pacific, is reflected in the Fe and Mn distribution in metalliferous sediments of hydrothermal origin. Investigations at 21.5–23.5°S EPR show that at a downstream distance of 10 km from the vents the total Fe and Mn contents are lower than those on the flanks. Primary suspended Mn precipitates more than 20 km from the high-temperature vents, whereas the main suspended Fe precipitates within 10 km of the active vent area. In the vicinity of the vents a zone of ‘geochemical minimum’ was observed. Bacterial masses were observed in plumes and sediments in hydrothermal sites of the Pacific. Microbial coenoses were studied to show the increased activity of heterotrophic and Fe-Mn bacteria at several horizons of MAR hydrothermal plumes. Near-surface plumes studied in Matupi Harbour (New Britain) were characterized by both the separation of suspended Fe and Mn horizontally and a corresponding increased presence of micro-organisms. The activity of micro-organisms accompanied differentiation of the suspended and dissolved Mn at the periphery of the plume. Evidence suggests a significant role for bacteria in removing Mn from plumes in different regions of the ocean.

Metalliferous Sediments of the World Ocean

“…Based on the data of Mottl and McConachy (1990) and Feely et al (1994). It has been shown in numerous publications that in an ocean environment, including hydrothermal plumes, the oxidation and sorption of Mn(II) takes place with the participation of bacteria that oxidize manganese (Bromfield and David 1976;Rosson and Nealson 1982;Ehrlich 1983Ehrlich , 1985Edenborn et al 1985;Cowen et al 1986Cowen et al , 1990Tebo and Emerson 1986;Nealson et al 1988;Durant et al 1990;Tambiev and Demina 1992;Mandernack and Tebo 1993;Lilley et al 1995;Sudarikov et al 1995, et al). The Fe tot /Mn tot ratios in the uppermost parts of buoyant plumes together with the Fe h /Mn h ratio are used for estimating the loss of Fe from the buoyant plumes 32 and the transfer of Fe to the nonbuoyant plumes (Mottl and McConachy 1990;Rudnicki and Elderfield 1993;Field and Sherrell 2000).…”

“…Does the dissolved Mn pass mainly into the particulate matter in the nonbuoyant plumes, or into the particulate matter under the nonbuoyant plumes, or after the metal-bearing matter is deposited in the metalliferous sediments on the seafloor? 1. 5, 1.7;Boström and Peterson 1969;Dymond 1981;Kunzendorf et al 1984Kunzendorf et al /1985Müller et al 1985;Walter and Stoffers 1985;Gurvich 1988;Dekov 1994;Sudarikov et al 1995;Renner et al 1997). 4.3.2) provide evidence which shows that only in the high productive zones or locally in areas where there are high concentrations of volatile gases are the Mn part /Fe part ratios comparable with the Mn/Fe ratios in the metal-bearing matter in the distal metalliferous sediments, 0.25 to 0.35 (Fig 4.18,4.20), and usually they are lower.…”

Design of an In Situ Process Analyzer Instrument for Organism Measurement Underwater

“…The marine microorganisms play an important role in marine energy flux, environmental surveillance, cycle process of elements such as carbon and nitrogen and so on [1][2]. Therefore, it is indispensable to know the quantity of microbial biomass in the deep sea.…”