An Integrated Microfluidic System for Manganese Anomaly Detection Based on Chemiluminescence: Description and Practical Use to Discover Hydrothermal Plumes Near the Okinawa Trough | IEEE Journals & Magazine | IEEE Xplore

An Integrated Microfluidic System for Manganese Anomaly Detection Based on Chemiluminescence: Description and Practical Use to Discover Hydrothermal Plumes Near the Okinawa Trough


Abstract:

Underwater hydrothermal vents draw a lot of interest as they are the shelter for unique ecosystems, besides being a possible new opportunity for ore mining. Manganese (Mn...Show More

Abstract:

Underwater hydrothermal vents draw a lot of interest as they are the shelter for unique ecosystems, besides being a possible new opportunity for ore mining. Manganese (Mn) is found at a high concentration in hydrothermal vents, which make it possible to use this metal ion as a tracer to detect and evaluate new hydrothermal sources. Here we present a miniaturized and integrated microfluidic system for the detection of Mn in deep-sea environment, called the integrated in situ analyzer for Mn2+ (IISA-Mn). The detection system is based on the chemiluminescence reaction of Mn contained in the seawater sample with a luminol-based reagent, which offers a high sensitivity. This system is composed of a microdevice for mixing and reaction, a pumping unit, several valving units, and a photomultiplier (PMT) detector. The system is able to detect Mn concentration above 280 nM in seawater, and gives a quite linear response until 500 nM. It is also proven to be able to work continuously during the 8 h of an actual remotely operated vehicle (ROV) dive. This system has led to the discovery of a previously unknown hydrothermal site in the Okinawa Trough.
Published in: IEEE Journal of Oceanic Engineering ( Volume: 38, Issue: 1, January 2013)
Page(s): 178 - 185
Date of Publication: 27 August 2012

ISSN Information:


I. Introduction

Hydrothermal vents located underwater near volcanic rifts are a place where unique ecosystems have developed, relying on the energy provided by the hot water and the organic carbon produced by chemosynthetic microbes [1]. Moreover these underwater hot springs play an important role in ocean geochemistry since many metal ions are coming into the sea through them [2]. In the long run, polymetallic nodules (including manganese, iron, copper, etc.) deposit on the seafloor near the vents, which may become a new source for metallic ore mining [3]. Manganese (Mn) is an element that is usually found at the nanomolar level in the ocean [4] but can attain several micromolars in hydrothermal fluids [5]. It is thus a good candidate for a marker for the detection of hydrothermal vents. The ideal method for detection of Mn2 + should show both a high sensitivity and a good linearity over a wide range of concentrations, and should also be able to be miniaturized sufficiently to fit in compact autonomous underwater vehicles (AUVs) or remotely operated vehicles (ROVs) for in situ real-time monitoring. The in situ measurement further avoids the contamination problems during handling and storage of bottled samples, and allows the detailed mapping of Mn distribution in the ocean. Only a few detection systems actually performing in situ monitoring of Mn concentration in seawater are reported and they are either based on chemiluminescence [6] or on spectrophotometry [7]–[9]. Such techniques could benefit from microfluidics [10] since it allows the development of miniaturized devices that have a faster response, use less quantity of reagents, occupy less volume, and consume less power than their macroworld counterparts, and which have already proved efficient in ocean environment [11].

References

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