TY - JOUR
T1 - Vertical profiles of arsenic and arsenic species transformations in deep-sea sediment, Nankai Trough, offshore Japan
AU - Masuda, Harue
AU - Yoshinishi, Haruka
AU - Fuchida, Shigeshi
AU - Toki, Tomohiro
AU - Even, Emilie
N1 - Funding Information:
The authors sampled the studied sediments and IW in collaboration with the crews and onboard scientists of Expeditions 338 and 348. The stored samples taken during Expedition 315 were provided by the Kochi Core Center, which is directed by Dr. Lalan Gupta. T. Shimonaka and K. Okazaki supported for conducting shore-based laboratory analyses. The comments from Dr. T. Kakegawa and two anonymous reviewers were helpful to improve the manuscript. We thank to all of them. This study was financially supported by post-cruise IODP studies to HM, SF and EE, and KAKENHI (No. 17K18810).
Funding Information:
The authors sampled the studied sediments and IW in collaboration with the crews and onboard scientists of Expeditions 338 and 348. The stored samples taken during Expedition 315 were provided by the Kochi Core Center, which is directed by Dr. Lalan Gupta. T. Shimonaka and K. Okazaki supported for conducting shore-based laboratory analyses. The comments from Dr. T. Kakegawa and two anonymous reviewers were helpful to improve the manuscript. We thank to all of them. This study was financially supported by post-cruise IODP studies to HM, SF and EE, and KAKENHI (No. 17K18810). Samples were collected on Drilling Vessel “Chikyu” under IODP program during Expeditions 338 and 348. Post cruise research fund from JAMSTEC for HM, SF and EE and KAKENHI (No. 17K18810) were used for As analyses. All data newly obtained from this study is in the manuscript and data sharing is not applicable.
Publisher Copyright:
© 2019, The Author(s).
PY - 2019/12/1
Y1 - 2019/12/1
N2 - Concentrations of arsenic (As) and its chemical forms were determined on deep-sea sediments drilled at three sites of Nankai Trough, off the Kii Peninsula, Japan. Those sediments were analyzed to document the behavior of As in relation to methane hydrate formation and the deep biosphere. The analytical results showed the total As concentration of interstitial water (IW) and squeezed cake (SC) ranged from 0.9 to 380 ppb and from 3 to 14 ppm (average, 6.4 ppm), respectively. The sediments from Site C0002, of which sediment column was the longest down to 2200 m below the seafloor (mbsf) among the studied three drilling sites, were analyzed for the host phase transformation of As. The total concentration of As of IW and SC from 200 to 500 mbsf, where methane hydrate zone was included, was higher than those from the uppermost 200 m. Concentration of As was ultimately controlled by pH. Also, organoarsenicals, such as methylarsonic acid (MMA) and arsenobetaine (AsB), were detected in the sediment column, implying that these organoarsenicals appeared in relation to the in situ microbial activities. These observations suggest that As becomes mobilized directly or indirectly as a result of microbial activity in deep-sea sediments. [Figure not available: see fulltext.]
AB - Concentrations of arsenic (As) and its chemical forms were determined on deep-sea sediments drilled at three sites of Nankai Trough, off the Kii Peninsula, Japan. Those sediments were analyzed to document the behavior of As in relation to methane hydrate formation and the deep biosphere. The analytical results showed the total As concentration of interstitial water (IW) and squeezed cake (SC) ranged from 0.9 to 380 ppb and from 3 to 14 ppm (average, 6.4 ppm), respectively. The sediments from Site C0002, of which sediment column was the longest down to 2200 m below the seafloor (mbsf) among the studied three drilling sites, were analyzed for the host phase transformation of As. The total concentration of As of IW and SC from 200 to 500 mbsf, where methane hydrate zone was included, was higher than those from the uppermost 200 m. Concentration of As was ultimately controlled by pH. Also, organoarsenicals, such as methylarsonic acid (MMA) and arsenobetaine (AsB), were detected in the sediment column, implying that these organoarsenicals appeared in relation to the in situ microbial activities. These observations suggest that As becomes mobilized directly or indirectly as a result of microbial activity in deep-sea sediments. [Figure not available: see fulltext.]
KW - Convergent margin
KW - Deep biosphere
KW - Nankai Trough
KW - Organoarsenical
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U2 - 10.1186/s40645-019-0269-y
DO - 10.1186/s40645-019-0269-y
M3 - Article
AN - SCOPUS:85063293766
SN - 2197-4284
VL - 6
JO - Progress in Earth and Planetary Science
JF - Progress in Earth and Planetary Science
IS - 1
M1 - 28
ER -