Sea Water Testing

Li, Gengchen, et al. Sensors and Actuators B: Chemical 420 (2024): 136469.

Phosphate, as a nutrient salt, can significantly impact fishery production and the ecological environment when present in high concentrations in seawater. However, rapid and direct detection of phosphate in seawater is challenging due to interference from hypersaline conditions and complex water components.

In this study, Ni/ZnO/P-rGO foam is developed for the direct detection of phosphate in seawater, utilizing electrostatically induced barrier changes to drive the electrochemical response to phosphate. Additionally, the photo-assisted Schottky barrier effect is explored, enhancing sensitivity by 2.06 times and reducing the detection limit to 0.20 μM. The Ni foam-based electrochemical electrode demonstrates a high recovery rate (97.8–105%) and excellent stability in seawater, along with strong resistance to seawater interference. The photo-assisted Schottky barrier effect shows promise for ensuring anti-interference performance, making it a potential solution for practical applications in seawater and other challenging environments.

Zhuang, Jingyu, et al. Aquaculture 595 (2025): 741651.

Amyloodinium ocellatum is a significant ectoparasite of marine fish, causing amyloodiniosis and mass mortality in aquaculture. Currently, there is no established diagnostic method for detecting and quantifying parasite abundance in seawater.

In this study, a quantitative real-time PCR (qPCR) assay using the ITS-F3 and ITS-R3 primer pair, targeting the internal transcribed spacers of nuclear ribosomal DNA (ITS rDNA) of A. ocellatum, was developed for detecting and quantifying dinospores in seawater. Dinospores were collected from seawater via suction filtration with a vacuum pump, and light microscopy and scanning electron microscopy (SEM) confirmed that the dinospores were adsorbed onto the surface of the cellulose acetate membrane. A strong linear correlation between seawater parasite abundance and Ct values was observed, following the model y = −3.0607x + 29.919, with an R² of 0.985. The assay demonstrated high reproducibility and no cross-reactivity with other aquatic pathogens. It successfully detected dinospores with a 100% success rate at concentrations of 8 and 10 cells per 300 mL of seawater.

Meng, Weichen, et al. Analytica Chimica Acta 1309 (2024): 342685.

Monitoring heavy metal ions in the ocean is essential for environmental protection and assessing seawater quality. However, the use of electrochemical sensors for long-term monitoring of heavy metal ions in seawater faces challenges due to marine biofouling, which results from nonspecific adsorption of microbial and biomolecules.

In this study, an electrochemical aptasensor with both antifouling and antibacterial properties was developed for the detection of Hg²⁺ in seawater. The sensor utilized eco-friendly peptides with high hydrophilicity to prevent nonspecific adsorption on the sensing interface, while silver nanoparticles were incorporated to eliminate bacteria. A ferrocene-modified aptamer was used for specific Hg²⁺ recognition. Upon interaction with Hg²⁺, the aptamer folds into a thymine-Hg²⁺-thymine (T-Hg²⁺-T) structure, bringing ferrocene closer to the sensor surface and significantly enhancing the electrochemical response.

This electrochemical aptasensor effectively minimized nonspecific adsorption in seawater while maintaining a sensitive electrochemical response. It exhibited a linear response range from 0.01 to 100 nM and a detection limit of 2.30 pM, enabling accurate monitoring of mercury ions in real marine environments. The findings provide valuable insights into the development of marine antifouling sensing devices, and sensors with antifouling and antimicrobial properties are expected to have broad applications in monitoring marine pollutants.