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Front. Mar. Sci. | doi: 10.3389/fmars.2018.00431

In situ determination of nitrate and hydrogen sulfide in the Baltic Sea using an ultraviolet spectrophotometer

 David Meyer1*,  Ralf D. Prien1,  Louis Rautmann1, Malte Pallentin1, Joanna J. Waniek1 and Detlef E. Schulz-Bull1
  • 1Leibniz Institute for Baltic Sea Research (LG), Germany

Evaluating the health status of marine ecosystems becomes ever increasingly important especially
against the backdrop of rising pressures from human activities. This is true especially for
coastal seas such as the Baltic Sea that is surrounded by highly industrialized countries. Nutrients
and pollutants such as nitrate and hydrogen sulfide, which have a major impact on ecosystem
functioning, are two of several key environmental indicators for assessing the status of natural
waters, and therefore of considerable interest. The frequency and the spatial coverage of the
nitrate and hydrogen sulfide measurements are currently limited by the cost of the laboratory
analysis and personnel. Optical in situ sensors can help to overcome this challenge by allowing
reagentless and fast detection of dissolved chemical species.

A chemical-free optical sensor has been used for direct and simultaneous measurements of both
key parameters, and the results were compared with traditional methods. The data were collected
during an observational program conducted in the Baltic Sea in February 2018. We used the
OPUS UV spectral sensor, which was deployed for the first time in coastal waters, in combination
with a deep-sea telemetry system to enable near-real time measurements during CTD profiling.
Data processing was carried out using a multiple linear regression procedure. Measurements
from both OPUS and on-board analysis were in good agreement. The results showed, that in situ
UV-VIS spectrophotometry provides the capability to determine the concentration distributions of
nitrate and hydrogen sulfide in the brackish waters of the Baltic Sea.

Keywords: Baltic Sea, UV-vis spectrophotometry, Nutrients, sulfide, Monitoring, hypoxia

Received: 28 Aug 2018; Accepted: 29 Oct 2018.

Edited by:

Hervé CLAUSTRE, Centre national de la recherche scientifique (CNRS), France

Reviewed by:

Oliver Zielinski, University of Oldenburg, Germany
Orens De Fommervault, Alseamar, France
Carole M. Sakamoto, Monterey Bay Aquarium Research Institute (MBARI), United States  

Copyright: © 2018 Meyer, Prien, Rautmann, Pallentin, Waniek and Schulz-Bull. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. David Meyer, Leibniz Institute for Baltic Sea Research (LG), Warnemünde, Germany, david.meyer@io-warnemuende.de