Frontiers in Marine Science (Nov 2024)

Automatic in situ sensor based on K2S2O8 oxidation method for total phosphorus detection in marine water

  • Yanmin Zhang,
  • Yanmin Zhang,
  • Shougang Chen,
  • Yan Liu,
  • Yan Liu,
  • Yan Zou,
  • Yan Zou,
  • Yang Wang,
  • Yang Wang,
  • Shuwei Zhang,
  • Shuwei Zhang,
  • Xiangfeng Kong,
  • Xiangfeng Kong,
  • Yang Gao,
  • Yang Gao,
  • Nan Gao,
  • Nan Gao

DOI
https://doi.org/10.3389/fmars.2024.1492115
Journal volume & issue
Vol. 11

Abstract

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Phosphorus is a key indicator for water quality management due to its role in eutrophication. The variety of phosphorus-containing substances necessitates highly sensitive detection of total phosphorus, particularly through automated methods, to ensure water safety. This study involved the independent development of a sensor featuring an automated in situ detection technique. Utilizing potassium persulfate high-temperature oxidation and phosphorus molybdenum blue spectrophotometry, total phosphorus was monitored in situ via sequential injection technology. Additionally, the detection process and reaction conditions of the sensor were optimized, and a temperature compensation algorithm and turbidity correction were applied to mitigate environmental factors. Under optimal conditions, the sensor demonstrated a detection limit of 1.9 µg/L with a range of 6.5–1000 µg/L in seawater, and 1.2 µg/L with a range of 4.1–2000 µg/L in freshwater. The digestion efficiency for five representative phosphorus-containing substances was found to range from 87.3% ± 1.7% to 103.1% ± 0.6%. Notably, the sensor was deployed for in situ operation at a marine experimental station and online at a river monitoring station. With its integration, low power consumption, and high precision, the sensor enabled long-term unattended monitoring, delivering accurate, stable, and reliable results.

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