The influence of particle composition on Thorium scavenging in the NE Atlantic ocean (POMME experiment)
The influence of particle composition on Thorium scavenging in the NE Atlantic ocean (POMME experiment)
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DOI：
10.1016/j.epsl.2005.09.059
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发表时间：
2005-12
影响因子：
5.3
通讯作者：
M. Roy‐Barman;C. Jeandel;M. Souhaut;M. Loeff;I. Voege;N. Leblond;R. Freydier
中科院分区：
文献类型：
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作者：
M. Roy‐Barman;C. Jeandel;M. Souhaut;M. Loeff;I. Voege;N. Leblond;R. Freydier
为了限制水体中携带Th同位素的相，对东北大西洋（POMME）系泊和漂流沉积物捕集器收集的沉降颗粒中的230 Th、232 Th和234 Th进行了分析。它揭示了对比behaviorbetween 234 Th和230 Th。234 Th相关的颗粒有机碳，这表明它主要是由地表水中的有机化合物清除。230 Thxsis相关的Mn，Ba和成岩馏分，富集在小悬浮颗粒，并纳入下沉颗粒通量在整个水柱。230 Thx与CaCO 3或生物硅（bSi）之间缺乏相关性CaCO 3和bSi对230 Th的清除作用不明显，230 Th与沉积物中的成岩物质含量有一定的相关性，但这种相关性在冬季强沙尘输入时消失，说明成岩物质对230 Th的清除作用不直接沃茨或需要足够的时间来实现颗粒-溶液平衡。MnO 2可能是主要的230 Thxs相。Kd_MnO_2Th的范围很窄，这支持了MnO_2对230 Th的清除作用是全球性的控制，并提出了海水中胶体MnO_2含量控制230 Th-231 Pa分馏的可能性。
230Th,232Th and234Th were analyzed in sinking particles collected by moored and drifting sediment traps in the NE Atlantic Ocean (POMME experiment) in order to constrain the phase(s) carrying Th isotopes in the water column. It reveals a contrasted behaviour between234Th and230Th.234Th is correlated to the particulate organic carbon suggesting that it is primarily scavenged by organic compounds in the surface waters.230Thxsis correlated with Mn, Ba and the lithogenic fraction that are enriched in small suspended particles and incorporated in the sinking particulate flux throughout the water column. The lack of correlation between230Thxsand CaCO3or biogenic silica (bSi) indicates that CaCO3and bSi are not responsible for230Th scavenging in the deep waters of this oceanic region.230Th is generally correlated with the lithogenic content of the trapped material but this correlation disappears in winter during strong atmospheric dust inputs suggesting that lithogenic matter is not directly responsible for230Th scavenging in the deep waters or that sufficient time is required to achieve particle–solution equilibration. MnO2could be the prevalent230Thxs-bearing phase. The narrow range of Kd_MnO2Thobtained for very contrasted oceanic environments supports a global control of230Thxsscavenging by MnO2and raises the possibility that the230Th–231Pa fractionation is controlled by the amount of colloidal MnO2in seawater.