WAIS Divide: Fluorimetry, Dust Logs, Climatology, Glaciology, Volcanology

价格/1142178这个奖项支持一个项目，继续测量WAIS冰层中叶绿素(Chl)和色氨酸(Trp)的含量，如果钻探继续低于3330米，则测量深度为3330米或更深。一种新型的微生物活/死染色将被用来确定这种下降是否与微生物的死亡率有关，这些微生物是导致强度随深度缓慢下降的原因。之前对GISP2冰的研究表明，核心更深部位的甲烷浓度比气候变化造成的变化高出一个数量级。之前的工作得出的结论表明，甲烷的激增是由于冰层中冻结时正在新陈代谢的那些深处的甲烷菌造成的。利用伯克利荧光光谱仪(BFS)，将在国家冰芯实验室(NICL)对WAIS分冰块进行测量，以寻找Trp和Chl异常大的尖峰，这将向气体化学家提供准确的深度，以寻找气体异常(即可能与气候无关的浓度尖峰)。在NICL对GISP2冰的荧光扫描中，发现许多深度的Trp增加，对应于一氧化二氮(N2O)尖峰的深度。用405 nm激光激发的流式细胞术也将用于寻找~465 nm处的F420自发荧光发射作为产甲烷菌的特征。之前用光学记录仪进行的测量使得在穹顶C冰芯中发现的火山灰层比用其他方法发现的要多得多。最近的发现是，在WAIS分水岭底部新钻的钻孔测井，产生了更高分辨率的尘埃图案，并比在较老的钻孔中发现的明显可分解的火山灰层密度高得多，这一点将被探索。利用这些新的冰芯记录结果，将有可能看到是否有火山灰层与在其他地点发现的火山灰层在时间上重合，并将加强现有证据，证明大规模火山喷发与尘埃记录中的尖峰之间存在因果关系，这表明气候突然变化。这项工作的学术价值在于，这些数据将有助于更好地理解导致冰层中气体杂质的过程，并有助于更好地理解全球火山活动与气候之间的联系。最后，47个微型倾斜仪被安装在冻结到冰立方阵列中的光学模块中的不同深度和横向位置的冰中。近一年来，他们一直在记录倾斜。这些数据将再分析三年，这将为研究作为剪切应力函数的巨大冰冷冰层的剪切应变率提供一个独特的机会。这项工作的更广泛影响包括应用于火星探索、古冰生命研究、海洋学、湖沼学、气象学、气候学和火山学。该项目将有助于教育和培训来自美国和其他国家的广泛的本科生、研究生和博士后。

Price/1142178This award supports a project to continue the measurements of chlorophyll (Chl) and tryptophan (trp) in WAIS Divide ice down to 3330 m, or deeper if drilling continues below 3330 m. A new type of live/dead stain for microbes will be used to see if the decrease is related to the death rate of microbes responsible for the slow decrease of intensity with depth. Previous work on GISP2 ice has shown that methane concentrations in deeper sections of the core were an order of magnitude higher than the variations due to climate change. The conclusion from the prior work suggested that the methane spikes were due to methanogens at those depths that were metabolizing while frozen in the ice. With the Berkeley Fluorescence Spectrophotometer (BFS) measurements will be made on WAIS Divide ice at the National Ice Core Laboratory (NICL) to look for unusually large spikes of Trp and Chl that will inform gas chemists of the exact depths to look for gas anomalies (i.e., concentration spikes that may not be related to climate). In fluorimetric scanning of GISP2 ice at NICL, increases in Trp were found at many depths, corresponding to depths with nitrous oxide (N2O) spikes. Flow cytometry with excitation by a 405 nm laser will also be used to look for F420 autofluorescence emission at ~465 nm as a signature of methanogens. Previous measurements with the optical logger enabled many more volcanic ash layers to be found in the Dome C ice core than had been found with other methods. The recent discovery that logging of a freshly drilled borehole, to the bottom of WAIS Divide, resulted in a higher-resolution dust pattern and a far greater concentration of clearly resolvable volcanic ash layers than had been found in older boreholes is something that will be explored. Using these new ice core logging results, it will be possible to see if any ash layers coincide in time with volcanic ash layers that have been found at other sites and will strengthen existing evidence for a causal relationship between large volcanic eruptions and spikes in the dust log, indicative of abrupt climate changes. The intellectual merit of the work is that the data will contribute to a better understanding of the processes that contribute to gaseous impurities in the ice and to developing a better understanding of the link between global volcanism and climate. Finally, 47 micro-inclinometers are installed in the ice at various depths and lateral positions in optical modules that are frozen into the IceCube array. They have been recording tilt for nearly a year. These data will be analyzed for an additional three years which will provide an unique opportunity to study the shear-strain rate of a huge volume of cold glacial ice as a function of shear stress. The broader impacts of the work include the possibility of applications to Mars exploration, studies of life in ancient ice, oceanography, limnology, meteorology, climate and volcanology. The project will contribute to the education and training of a broad range of undergraduate and graduate students and post-docs from the U. S. and other countries.