Collaborative Research: Development of SF5CF3 for Ocean Tracer Release Experiments

在海洋中使用六氟化硫（SF6）的示踪剂释放实验已被证明是研究海洋混合的有力工具。 需要SF6的替代物，因为SF6的释放会干扰其作为从大气侵入海洋的瞬态示踪剂的非常有希望的用途。 迄今为止，只有一小部分海洋被SF6污染，但在南大洋进行的一项示踪剂释放实验是有前景的，在南大洋，SF6将作为一种瞬态示踪剂非常有用。在这项研究中，伍兹霍尔海洋研究所和哥伦比亚大学的研究人员将评估一种有前途的新示踪剂，五氟化三氟甲基硫（SF 5CF 3）。 SF 5CF 3的一个重要优势是其在海洋中的背景浓度几乎无法检测，而SF6的背景浓度限制了预期示踪剂释放实验的有效持续时间。 研究人员已经发现，SF 5CF 3的最低可检测水平与SF6一样低。 关于新示踪剂的一个问题是，它可能与水中的颗粒相互作用，足以不像SF6那样跟随水。 对SF6和SF 5CF 3与1-辛醇、碳酸钙颗粒和二氧化硅颗粒的亲和力进行的初步实验室测量表明，这两种化合物在海洋中的颗粒上的迁移不应被检测到。 另一方面，在海洋实验中，SF6本身似乎每年下降3到10米。 因此，他们计划改进和扩展他们的实验室测量。 他们还将在圣莫尼卡盆地一起释放两种示踪剂进行实地测试，并跟踪示踪剂的分布两年，以确定SF 5CF 3是否是示踪剂释放实验中SF6的可行替代品。 更广泛的影响：用示踪剂释放实验研究海洋中的混合情况，以及用瞬态示踪剂研究水团年龄，都是全面研究海洋环流和海洋吸收化石燃料燃烧释放到环境中的大量二氧化碳的能力的重要方面。 在海洋学工具包中增加新的示踪剂将大大有助于技术发展，正如1960年代增加炸弹示踪剂、1970年代增加氦-3和CFC以及1980年代增加SF6所证明的那样。 SF6还成功地用于河口的迁移和扩散研究。第二种示踪剂的可用性将增加这种实验的多功能性和力量。 最后，作为教育的一部分，研究人员将聘请一名本科生每年夏天参加圣莫尼卡盆地的游轮和实验室工作。

ABSTRACTOCE-0425197Tracer release experiments using sulfur hexafluoride (SF6) in the ocean have proven to be a powerful tool in the study of ocean mixing. An alternative to SF6 is desired because releases of SF6 can interfere with its very promising use as a transient tracer invading the ocean from the atmosphere. Only a small fraction of the ocean has been tainted with SF6 thus far, but in prospect is a tracer release experiment in the Southern Ocean, a region for which SF6 would be very useful as a transient tracer.In this study, researchers at the Woods Hole Oceanographic Institution and Columbia University will evaluate a promising new tracer, trifluoromethyl sulfur pentafluoride (SF5CF3). An important advantage of SF5CF3 is that its background concentration in the ocean is virtually undetectable, while that of SF6 limits the useful duration of prospective tracer release experiments. The researchers have already found that the minimum detectable level of SF5CF3 is as low as that of SF6. A concern about the new tracer is that it may interact with particles in the water strongly enough to not follow the water as well as SF6. Preliminary laboratory measurements of the affinity of SF6 and of SF5CF3 to 1-octanol, to calcium carbonate particles, and to silica particles have shown that transport on particles in the ocean should not be detectable for either compound. On the other hand, SF6 itself seems to have fallen 3 to 10 meters per year in the ocean experiments. Hence they plan to refine and to extend their laboratory measurements. They will also conduct a field test by releasing both tracers together in Santa Monica Basin and following the distributions of the tracers for two years to determine whether SF5CF3 is a viable substitute for SF6 for tracer release experiments. Broader Impacts: Both the study of mixing in the ocean with tracer release experiments and the study of water mass ages using transient tracers are important aspects of the overall study of the ocean circulation and of the ability of the ocean to take up the large amounts of carbon dioxide that are being released to the environment by the burning of fossil fuels. Adding a new tracer to the oceanographic toolkit would contribute significantly to technology, as was demonstrated to be the case when bomb tracers were added in the 1960s, when helium-3 and CFCs were added in the 1970s, and when SF6 was added in the 1980s. SF6 has also been used successfully in transport and dispersion studies in estuaries. The availability of a second tracer would add versatility and power to such experiments. Finally, as an educational component, the researchers will hire an undergraduate student to work each summer to participate in the cruises in Santa Monica Basin and in the laboratory work.