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Investigation of two novel approaches for detection of sulfate ion and methane dissolved in sediment pore water using Raman spectroscopy.

Du Z, Chen J, Ye W, Guo J, Zhang X, Zheng R - Sensors (Basel) (2015)

Bottom Line: With the aid of LCOF, the Raman signal of SO42- is found to be enhanced over 10 times compared to that obtained by a conventional Raman setup.The enrichment process is also found to be effective in the investigation to the prepared sample of methane dissolved in water.All the obtained results suggest that the approach proposed in this paper has great potential to be developed as a sensor for SO42- and CH4 detection in pore water.

View Article: PubMed Central - PubMed

Affiliation: Optics and Optoelectronics Laboratory, Ocean University of China, Qingdao 266100, China. mofeng212@163.com.

ABSTRACT
The levels of dissolved sulfate and methane are crucial indicators in the geochemical analysis of pore water. Compositional analysis of pore water samples obtained from sea trials was conducted using Raman spectroscopy. It was found that the concentration of SO42- in pore water samples decreases as the depth increases, while the expected Raman signal of methane has not been observed. A possible reason for this is that the methane escaped after sampling and the remaining concentration of methane is too low to be detected. To find more effective ways to analyze the composition of pore water, two novel approaches are proposed. One is based on Liquid Core Optical Fiber (LCOF) for detection of SO42-. The other one is an enrichment process for the detection of CH4. With the aid of LCOF, the Raman signal of SO42- is found to be enhanced over 10 times compared to that obtained by a conventional Raman setup. The enrichment process is also found to be effective in the investigation to the prepared sample of methane dissolved in water. By CCl4 extraction, methane at a concentration below 1.14 mmol/L has been detected by conventional Raman spectroscopy. All the obtained results suggest that the approach proposed in this paper has great potential to be developed as a sensor for SO42- and CH4 detection in pore water.

No MeSH data available.


Typical Raman spectrum of the pore water samples.
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sensors-15-12377-f002: Typical Raman spectrum of the pore water samples.

Mentions: A compact spectrometer (QE65000 Pro, from Ocean Optics, Dunedin, FL, USA) is used to acquire Raman spectra of pore water samples with an integration time of 1 s, and the original Raman spectrum of the pore water samples is shown in Figure 2. The results show that the Raman peak of SO42− at 981 cm−1 is obviously detected, while the expected Raman peak of methane at 2917 cm−1 cannot be detected. A possible reason for this s that the methane dissolved in pore water has escaped after sampling and the concentration of the remaining methane is too low to be detected.


Investigation of two novel approaches for detection of sulfate ion and methane dissolved in sediment pore water using Raman spectroscopy.

Du Z, Chen J, Ye W, Guo J, Zhang X, Zheng R - Sensors (Basel) (2015)

Typical Raman spectrum of the pore water samples.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507585&req=5

sensors-15-12377-f002: Typical Raman spectrum of the pore water samples.
Mentions: A compact spectrometer (QE65000 Pro, from Ocean Optics, Dunedin, FL, USA) is used to acquire Raman spectra of pore water samples with an integration time of 1 s, and the original Raman spectrum of the pore water samples is shown in Figure 2. The results show that the Raman peak of SO42− at 981 cm−1 is obviously detected, while the expected Raman peak of methane at 2917 cm−1 cannot be detected. A possible reason for this s that the methane dissolved in pore water has escaped after sampling and the concentration of the remaining methane is too low to be detected.

Bottom Line: With the aid of LCOF, the Raman signal of SO42- is found to be enhanced over 10 times compared to that obtained by a conventional Raman setup.The enrichment process is also found to be effective in the investigation to the prepared sample of methane dissolved in water.All the obtained results suggest that the approach proposed in this paper has great potential to be developed as a sensor for SO42- and CH4 detection in pore water.

View Article: PubMed Central - PubMed

Affiliation: Optics and Optoelectronics Laboratory, Ocean University of China, Qingdao 266100, China. mofeng212@163.com.

ABSTRACT
The levels of dissolved sulfate and methane are crucial indicators in the geochemical analysis of pore water. Compositional analysis of pore water samples obtained from sea trials was conducted using Raman spectroscopy. It was found that the concentration of SO42- in pore water samples decreases as the depth increases, while the expected Raman signal of methane has not been observed. A possible reason for this is that the methane escaped after sampling and the remaining concentration of methane is too low to be detected. To find more effective ways to analyze the composition of pore water, two novel approaches are proposed. One is based on Liquid Core Optical Fiber (LCOF) for detection of SO42-. The other one is an enrichment process for the detection of CH4. With the aid of LCOF, the Raman signal of SO42- is found to be enhanced over 10 times compared to that obtained by a conventional Raman setup. The enrichment process is also found to be effective in the investigation to the prepared sample of methane dissolved in water. By CCl4 extraction, methane at a concentration below 1.14 mmol/L has been detected by conventional Raman spectroscopy. All the obtained results suggest that the approach proposed in this paper has great potential to be developed as a sensor for SO42- and CH4 detection in pore water.

No MeSH data available.