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Abstract As global ocean monitoring programs and marine carbon dioxide removal methods expand, so does the need for scalable biogeochemical sensors. Currently, pH sensors are widely used to measure the ocean carbonate system on a variety of autonomous platforms. This paper assesses a commercially available optical pH sensor (optode) distributed by PyroScience GmbH for oceanographic applications. Results from this study show that the small, solid‐state pH optode demonstrates a precision of 0.001 pH and relative accuracy of 0.01 pH using an improved calibration routine outlined in the manuscript. A consistent pressure coefficient of 0.029 pH/1000 dbar is observed across multiple pH optodes tested in this study. The response time is investigated for standard and fast‐response versions over a range of temperatures and flow rates. Field deployments include direct comparison to ISFET‐based pH sensor packages for both moored and profiling platforms where the pH optodes experience sensor‐specific drift rates up to 0.006 pH d−1. In its current state, the pH optode potentially offers a viable and scalable option for short‐term field deployments and laboratory mesocosm studies, but not for long term deployments with no possibility for recalibration like on profiling floats.
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This content will become publicly available on April 3, 2026
The Piver’s Island Coastal Observatory – a decade of weekly+ observations reveal the press and pulse of a changing temperate coastal marine system
Historically, oceanographic time-series have focused on long-term measurements of large open ocean gyres; yet, the coastal oceans, with their high productivity, tidal impacts, human feedbacks, and land-sea coupling, represent critical regions for predicting ocean dynamics and biogeochemistry under global change. The Piver’s Island Coastal Observatory (PICO) time-series, located in the second largest estuarine system on the US East Coast (Albemarle-Pamlico Sound), comprises more than a decade of weekly (or more frequent) measurements of core physical, chemical, and biological oceanographic variables. PICO provides insight into a coastal, mesotrophic ecosystem in an ecologically-diverse and biochemically-active region impacted by global change. Here, we report on a decade of observations focusing on pulse and press ecosystem changes. We observe strong mean annual cycles in environmental variables including temperature (10.1-28.9°C), pH (7.89-8.12), dissolved inorganic carbon (DIC: 1965 – 2088 µM), chlorophyll (2.54-5.77 mg Chl m-3), upon which are layered episodic disturbances (e.g., tropical cyclones) that dramatically and persistently (>1 month) impact this ecosystem. Among other variables, long term trends in pH (-0.004 ± 0.001 y-1; p<0.01), DIC (-9.8 ± 1.5 µM y-1; p<0.01) and chlorophyll (-0.17 ± 0.02 µg L-1y-1; p<0.01) are exceeding those observed in the open ocean, suggesting an ecosystem in flux. These analyses provide a benchmark for future studies of the impact of changing climate and oceanographic climatology; further research will use this long-term research to developed targeted sampling and experimental manipulations to better understand ecosystem structure and function.
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- PAR ID:
- 10608027
- Publisher / Repository:
- Frontiers
- Date Published:
- Journal Name:
- Frontiers in Marine Science
- Volume:
- 12
- ISSN:
- 2296-7745
- Subject(s) / Keyword(s):
- time series coastal ocean annual cycles tropical cyclone
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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