In:
Applied Spectroscopy, SAGE Publications, Vol. 72, No. 1 ( 2018-01), p. 48-59
Abstract:
Deep-sea carbon dioxide (CO 2 ) plays a significant role in the global carbon cycle and directly affects the living environment of marine organisms. In situ Raman detection technology is an effective approach to study the behavior of deep-sea CO 2 . However, the Raman spectral characteristics of CO 2 can be affected by the environment, thus restricting the phase identification and quantitative analysis of CO 2 . In order to study the Raman spectral characteristics of CO 2 in extreme environments (up to 300 ℃ and 30 MPa), which cover most regions of hydrothermal vents and cold seeps around the world, a deep-sea extreme environment simulator was developed. The Raman spectra of CO 2 in different phases were obtained with Raman insertion probe (RiP) system, which was also used in in situ Raman detection in the deep sea carried by remotely operated vehicle (ROV) “Faxian”. The Raman frequency shifts and bandwidths of gaseous, liquid, solid, and supercritical CO 2 and the CO 2 –H 2 O system were determined with the simulator. In our experiments (0–300 ℃ and 0–30 MPa), the peak positions of the symmetric stretching modes of gaseous CO 2, liquid CO 2 , and supercritical CO 2 shift approximately 0.6 cm –1 (1387.8–1388.4 cm –1 ), 0.7 cm –1 (1385.5–1386.2 cm –1 ), and 2.5 cm –1 (1385.7–1388.2 cm –1 ), and those of the bending modes shift about 1.0 cm –1 (1284.7–1285.7 cm –1 ), 1.9 cm –1 (1280.1–1282.0 cm –1 ), and 4.4 cm –1 (1281.0–1285.4 cm –1 ), respectively. The Raman spectral characteristics of the CO 2 –H 2 O system were also studied under the same conditions. The peak positions of dissolved CO 2 varied approximately 4.5 cm –1 (1282.5–1287.0 cm –1 ) and 2.4 cm –1 (1274.4–1276.8 cm –1 ) for each peak. In comparison with our experiment results, the phases of CO 2 in extreme conditions (0–3000 m and 0–300 ℃) can be identified with the Raman spectra collected in situ. This qualitative research on CO 2 can also support the further quantitative analysis of dissolved CO 2 in extreme conditions.
Type of Medium:
Online Resource
ISSN:
0003-7028
,
1943-3530
DOI:
10.1177/0003702817722820
Language:
English
Publisher:
SAGE Publications
Publication Date:
2018
detail.hit.zdb_id:
1474251-2
SSG:
11
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