Luther III G.W.,University of Delaware |
Gartman A.,University of Delaware |
Yucel M.,University of Delaware |
Yucel M.,University Pierre and Marie Curie |
And 9 more authors.
Oceanography | Year: 2012
Diffuse-flow, low-temperature areas near hydrothermal vents support life via chemosynthesis: hydrogen sulfide (and other reduced chemical compounds) emanating from the subsurface is oxidized with bottom-water oxygen through bacterial mediation to fix carbon dioxide and produce biomass. This article reviews the in situ diffuse-flow chemistry (mainly H 2S and O 2) and temperature data collected in 2006 and 2009 along the Eastern Lau Spreading Center (ELSC), and from 2004 to 2008 at 9°N along the East Pacific Rise (9 N EPR), predominantly around macrofauna that contain endosymbionts at these two hydrothermal vent regions. More than 48,000 and 20,000 distinct chemical and temperature data points were collected with a multi-analyte electrochemical analyzer in the diffuse-flow waters at 9 N EPR and the ELSC, respectively. Despite their different geological settings and different macrofauna (two different species of snails and mussels at the ELSC versus two different species of tubeworms and mussels at 9 N EPR), there are similarities in the temperature and chemistry data, as well as in the distributions of organisms. The pattern of water chemistry preferred by the provannid snails (Alviniconcha spp., Ifremeria nautilei) and Bathymodiolus brevior at the ELSC is similar to the water chemistry pattern found for the siboglinid tubeworms (Tevnia jerichonana, Riftia pachyptila) and the Bathymodiolus thermophilus mussels at 9 N EPR. The eruptions at 9 N EPR in 2005 and 2006 resulted in increased H 2S concentrations, increased H 2S/T ratios, and an initial change in the dominant tubeworm species from Riftia pachyptila to Tevnia jerichonana after the eruption created new vent habitats. In 2005, two sites at 9 N EPR showed major increases in the H 2S/T ratio from 2004, which suggested a probable eruption in this basalt-dominated system. At the ELSC, there was a decrease in the H 2S/T ratio from northern to southern sites, which reflects the change in geological setting from basalt to andesite and the shallower water depths at the southern sites. © 2012 by The Oceanography Society.
Nuzzio D.B.,Analytical Instrument Systems Inc |
Zettler E.R.,Sea Education Association |
Aguilera A.,CSIC - National Institute of Aerospace Technology |
Amaral-Zettler L.A.,Josephine Bay Paul Center for Comparative Molecular Biology and Evolution |
Amaral-Zettler L.A.,Brown University
Science of the Total Environment | Year: 2011
Electrochemistry allows for rapid identification of multiple metals and other chemical complexes common in acid rock drainage (ARD) systems. Voltammetric scans using a single gold microelectrode of water samples from geochemically distinct areas of the Río Tinto (RT) in southwestern Spain were clearly recognizable in the field and in samples stored at room temperature for over 6. months. Major voltammetric peaks of iron(III) and copper(II) were identified on a single constantly renewable gold microelectrode. Confirmation of these peaks was performed by spiking with standard metal solutions in the laboratory. This voltammetric technique is a rapid, direct and inexpensive in situ method for identification of water sources and their chemical characteristics, as well as an economical way to monitor environmental changes and remediation efforts. © 2011 Elsevier B.V.
Delgard M.L.,University of Bordeaux 1 |
Deflandre B.,University of Bordeaux 1 |
Deflandre B.,CNRS Paris Institute of Global Physics |
Metzger E.,University of Angers |
And 4 more authors.
Hydrobiologia | Year: 2012
We investigated the composition of porewaters in intertidal sediments in response to the diurnal rise and fall of tides. For this reason, we deployed an in situ voltammetric system to measure vertical distribution and time-series at defined depths of O 2, Mn(II), Fe(II), and S(-II) in the porewater of permeable sediments from a protected beach in the Arcachon Bay. We also report microprofiles of O 2 and pH together with sediment properties (organic carbon, particulate reactive manganese and iron, porosity and permeability). Results shows that the oxygen dynamics in the upper sediment at low tide appeared to be mainly controlled by microphytobenthos activity, which may migrate downward just before immersion. The tidal forcing seemed to influence the oxygen dynamic in a minor way through flushing of the uppermost sediment porewater layer at the beginning and end of immersion. Vertical profiles and time-series measurements showed that the distributions of reduced species varied with tides. Although this work reveals that the upper sediment layer was subject to redox changes, the response of vertical distributions of redox species to tidal and night-day cycles did not have a cyclic pattern. © 2012 Springer Science+Business Media B.V.
Beckler J.S.,Georgia Institute of Technology |
Nuzzio D.B.,Analytical Instrument Systems Inc |
Taillefert M.,Georgia Institute of Technology
Limnology and Oceanography: Methods | Year: 2014
Although a number of techniques exist to measure the major and minor inorganic anions Cl-, NO2 -, Br-, NO3 -, or SO4 2- in marine waters and sediment porewaters, a single method that can quantify all five anions in a single step with a sufficiently low detection limit has yet to be developed. In this work, a novel ion-chromatographic separation procedure was developed that exploits the UV-absorbing properties of Br-, NO3 -, and NO2 -, as well as the suppression of eluent absorbance by high concentrations of Cl- and SO4 2- to quantify all these anions simultaneously in marine waters. If additional sensitivity for the minor anions Br-, NO3 -, and NO2 - is needed, NaCl can be used as eluent in a matrix elimination method that no longer allows for Cl- and SO4 2- determination. These methods are isocratic, require no chemical or electronic suppression, are not subject to interferences, and can resolve the anions in less than 18 min. The decrease in analysis time and the number of analyses required compared with conventional methods lowers the costs associated with laboratory analysis of marine samples. Last, the simplicity and good limits of detection make this separation method suitable for in situ analyses of marine waters and porewaters, and an in situ liquid chromatograph is currently under development for these applications. © 2014, by the American Society of Limnology and Oceanography, Inc.
Analytical Instrument Systems Inc. | Date: 2014-10-08
A system for acquiring environmental data from a plurality of sensors is provided with a microprocessor having a sensor input for receiving data from a sensor, a memory access port for communicating with a memory system, and an output port for issuing data. Plural sensors each produce associated sensor signals responsive to respective characteristics of an environment. The sensor signals are propagated to the sensor input of the microprocessor, and a memory system is coupled to the memory access port of the microprocessor for storing calibration data associated with the plurality of sensors. A communications arrangement is coupled to the output port of the microprocessor.