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Ringham M, Wang ZA, Sonnichsen F, Lerner S, McDonald G, Pfeifer J. Development of the Channelized Optical System II for In Situ, High-Frequency Measurements of Dissolved Inorganic Carbon in Seawater. ACS ES&T WATER 2024; 4:1775-1785. [PMID: 38633365 PMCID: PMC11019540 DOI: 10.1021/acsestwater.3c00787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 02/29/2024] [Accepted: 02/29/2024] [Indexed: 04/19/2024]
Abstract
This study describes the development of the CHANnelized Optical System II (CHANOS II), an autonomous, in situ sensor capable of measuring seawater dissolved inorganic carbon (DIC) at high frequency (up to ∼1 Hz). In this sensor, CO2 from acidified seawater is dynamically equilibrated with a pH-sensitive indicator dye encapsulated in gas-permeable Teflon AF 2400 tubing. The pH in the CO2 equilibrated indicator is measured spectrophotometrically and can be quantitatively correlated to the sample DIC. Ground-truthed field data demonstrate the sensor's capabilities in both time-series measurements and surface mapping in two coastal sites across tidal cycles. CHANOS II achieved an accuracy and precision of ±5.9 and ±5.5 μmol kg-1. The mean difference between traditional bottle and sensor measurements was -3.7 ± 10.0 (1σ) μmol kg-1. The sensor can perform calibration in situ using Certified Reference Materials (CRMs) to ensure measurement quality. The coastal time-series measurements highlight high-frequency variability and episodic biogeochemical shifts that are difficult to capture by traditional methods. Surface DIC mapping shows multiple endmembers in an estuary and highlights fine-scale spatial variabilities of DIC. The development of CHANOS II demonstrates a significant technological advance in seawater CO2 system sensing, which enables high-resolution, subsurface time-series, and profiling deployments.
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Affiliation(s)
| | - Zhaohui Aleck Wang
- Department of Marine Chemistry
& Geochemistry, Woods Hole Oceanographic
Institution, McLean 216, MS # 8, 266 Woods Hole Road, Woods
Hole, Massachusetts 02543, United States
| | - Frederick Sonnichsen
- Department of Marine Chemistry
& Geochemistry, Woods Hole Oceanographic
Institution, McLean 216, MS # 8, 266 Woods Hole Road, Woods
Hole, Massachusetts 02543, United States
| | - Steven Lerner
- Department of Marine Chemistry
& Geochemistry, Woods Hole Oceanographic
Institution, McLean 216, MS # 8, 266 Woods Hole Road, Woods
Hole, Massachusetts 02543, United States
| | - Glenn McDonald
- Department of Marine Chemistry
& Geochemistry, Woods Hole Oceanographic
Institution, McLean 216, MS # 8, 266 Woods Hole Road, Woods
Hole, Massachusetts 02543, United States
| | - Jonathan Pfeifer
- Department of Marine Chemistry
& Geochemistry, Woods Hole Oceanographic
Institution, McLean 216, MS # 8, 266 Woods Hole Road, Woods
Hole, Massachusetts 02543, United States
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Gray AR. The Four-Dimensional Carbon Cycle of the Southern Ocean. ANNUAL REVIEW OF MARINE SCIENCE 2024; 16:163-190. [PMID: 37738480 DOI: 10.1146/annurev-marine-041923-104057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/24/2023]
Abstract
The Southern Ocean plays a fundamental role in the global carbon cycle, dominating the oceanic uptake of heat and carbon added by anthropogenic activities and modulating atmospheric carbon concentrations in past, present, and future climates. However, the remote and extreme conditions found there make the Southern Ocean perpetually one of the most difficult places on the planet to observe and to model, resulting in significant and persistent uncertainties in our knowledge of the oceanic carbon cycle there. The flow of carbon in the Southern Ocean is traditionally understood using a zonal mean framework, in which the meridional overturning circulation drives the latitudinal variability observed in both air-sea flux and interior ocean carbon concentration. However, recent advances, based largely on expanded observation and modeling capabilities in the region, reveal the importance of processes acting at smaller scales, including basin-scale zonal asymmetries in mixed-layer depth, mesoscale eddies, and high-frequency atmospheric variability. Assessing the current state of knowledge and remaining gaps emphasizes the need to move beyond the zonal mean picture and embrace a four-dimensional understanding of the carbon cycle in the Southern Ocean.
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Affiliation(s)
- Alison R Gray
- School of Oceanography, University of Washington, Seattle, Washington, USA;
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Ahmad M, Ahmad A, Omar TFT, Mohammad R. Current Trends of Analytical Techniques for Total Alkalinity Measurement in Water Samples: A Review. Crit Rev Anal Chem 2023:1-11. [PMID: 37052389 DOI: 10.1080/10408347.2023.2199432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
Increasing acidity of seawater caused by increasing anthropogenic carbon dioxide absorbed into the seawater attracted the interest of researchers due to increased concern on the deterioration of marine systems and food supply to humans. Total alkalinity (TA) is one of the important parameters in determining carbonate chemistry and is described as the capacity of the sample to neutralize acids. Over the last two decades, many analytical techniques have been developed to determine TA. This article presents a review of different analytical techniques including titration, colorimetric, spectrophotometric, and potentiometric analyses in measuring TA. Among these analytical techniques, potentiometry analysis, which utilizes electrode systems such as glass electrode and ion-selective electrode used as indicator electrodes, is the most used technique. Important features such as principle, limitations, and challenges of the involved technique are discussed in detail.
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Affiliation(s)
- Mariani Ahmad
- Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Terengganu, Malaysia
| | - Azrilawani Ahmad
- Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Terengganu, Malaysia
- Ocean Pollution and Ecotoxicology Research Group, Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Terengganu, Malaysia
| | - Tuan Fauzan Tuan Omar
- Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Terengganu, Malaysia
- Ocean Pollution and Ecotoxicology Research Group, Faculty of Science and Marine Environment, Universiti Malaysia Terengganu, Terengganu, Malaysia
| | - Rosmawani Mohammad
- Faculty of Bioengineering and Technology, Jeli Campus, Universiti Malaysia Kelantan, Kelantan, Malaysia
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F. Guallart E, Fajar NM, García-Ibáñez MI, Castaño-Carrera M, Santiago-Doménech R, Hassoun AER, F. Pérez F, Easley RA, Álvarez M. Spectrophotometric Measurement of Carbonate Ion in Seawater over a Decade: Dealing with Inconsistencies. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:7381-7395. [PMID: 35670676 PMCID: PMC9228043 DOI: 10.1021/acs.est.1c06083] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 04/12/2022] [Accepted: 04/13/2022] [Indexed: 06/15/2023]
Abstract
The spectrophotometric methodology for carbonate ion determination in seawater was first published in 2008 and has been continuously evolving in terms of reagents and formulations. Although being fast, relatively simple, affordable, and potentially easy to implement in different platforms and facilities for discrete and autonomous observations, its use is not widespread in the ocean acidification community. This study uses a merged overdetermined CO2 system data set (carbonate ion, pH, and alkalinity) obtained from 2009 to 2020 to assess the differences among the five current approaches of the methodology through an internal consistency analysis and discussing the sources of uncertainty. Overall, the results show that none of the approaches meet the climate goal (± 1 % standard uncertainty) for ocean acidification studies for the whole carbonate ion content range in this study but usually fulfill the weather goal (± 10 % standard uncertainty). The inconsistencies observed among approaches compromise the consistency of data sets among regions and through time, highlighting the need for a validated standard operating procedure for spectrophotometric carbonate ion measurements as already available for the other measurable CO2 variables.
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Affiliation(s)
- Elisa F. Guallart
- Centro
Oceanográfico de A Coruña (COAC-IEO), CSIC, DC 15001, A Coruña, Spain
- Institut
de Ciències del Mar (ICM), CSIC, DC 08003 Barcelona, Spain
| | - Noelia M. Fajar
- Centro
Oceanográfico de A Coruña (COAC-IEO), CSIC, DC 15001, A Coruña, Spain
- Instituto
de Investigacións Mariñas (IIM), CSIC, DC 36208 Vigo, Spain
| | - Maribel I. García-Ibáñez
- Institut
de Ciències del Mar (ICM), CSIC, DC 08003 Barcelona, Spain
- School
of Environmental Sciences, University of
East Anglia (UEA), Norwich NR47TJ, United Kingdom
| | | | - Rocío Santiago-Doménech
- Centro
Oceanográfico de Baleares (COB-IEO), CSIC, DC 07015, Palma de Mallorca, Balearic Islands, Spain
| | - Abed El Rahman Hassoun
- GEOMAR
Helmholtz Centre for Ocean Research Kiel, D-24105 Kiel, Germany
- National
Center for Marine Sciences, National Council
for Scientific Research in Lebanon (CNRS-L), Beirut, Lebanon
| | - Fiz F. Pérez
- Instituto
de Investigacións Mariñas (IIM), CSIC, DC 36208 Vigo, Spain
| | - Regina A. Easley
- Chemical
Sciences Division, National Institute of
Standards and Technology (NIST), DC 20899, Gaithersburg, Maryland, United States
| | - Marta Álvarez
- Centro
Oceanográfico de A Coruña (COAC-IEO), CSIC, DC 15001, A Coruña, Spain
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