Krypton Isotope Hydrology

地下水的年龄是最难以量化的地质参数之一，尽管它对水资源，废物管理，地下反应运输和古气候研究具有重要意义。81 Kr是测定老地下水在5 ~ 10 ~ 4 ~ 10 ~ 6年范围内滞留时间的理想示踪剂，但由于其丰度低（81 Kr/Kr为10 ~（-12）），几乎不可能测定。然而，最近报道了一种在少量Kr（少至50微摩尔）中测量81 Kr/Kr比率的新技术（原子阱痕量分析，或ATTA; Chen等人，1999; Du等人，2003年），PI及其同事在其NSF资助的埃及努比亚含水层研究中成功地证明了其对旧地下水的应用（Sturchio等人，2003年）。该研究确定了在具有长地下水停留时间的系统的水文调查中使用ATTA技术进行常规81 Kr/Kr测量的可行性。ATTA技术也可用于测量85 Kr/Kr，因此是解决水文学中一系列基本问题的理想工具。T.阿贡国家实验室的Lu研究组）在水文调查中进一步开发痕量Kr同位素（81 Kr和85 Kr）的应用。本研究的学术价值在于，它将导致对地壳内水循环的进一步了解。我们建议的具体调查是：（1）确定美国中部咸水地下水的停留时间;根据稳定同位素数据，这些物质从落基山脉的补给区传播了1,000多公里，（Musgrove和Banner，1993年），因此其停留时间应为10 - 6年;（2）限制热液沃茨在黄石国家公园的停留时间，这方面的信息很少（Pearson和Truesdell，1978年）;（3）确定阿尔伯塔南部牛奶河含水层地下水的停留时间，这是国际原子能机构赞助的早期多示踪剂研究的主题，该研究的重点是确定非常古老的地下水的年代（Ivanovich，Frohlich和Hendry，1991年）;并调查年轻（50年）地下水的停留时间，其他示踪剂如氚-氦和CFC不能提供一致的结果。这些研究代表了微量氪同位素在地下水水文学中广泛的潜在应用。拟议研究的更广泛的影响是，它将为伊利诺伊大学芝加哥分校（UIC）提供研究、培训和教育的机会，该大学拥有全国第五大多样化的学生群体;它将在芝加哥地区建立一个更好地方机构，以便在水文学中常规应用微量氪同位素，因为Kr分离将在UIC的实验室里进行因为Kr分离将在UIC的实验室里进行（而不是像以前的NSF资助的研究那样在瑞士），ATTA测量在附近的阿贡国家实验室进行;它将有助于建立一个新的分支学科--Kr同位素水文学，这将对世界范围内的水文调查和水资源管理产生重要影响。

0409756SturchioThe age of groundwater is one of the most elusive geologic parameters to quantify, despite itscrucial significance for water resources, waste management, subsurface reactive transport, andpaleoclimate studies. It has long been recognized that 81 Kr is a nearly ideal tracer fordetermining residence times of old groundwater in the 5 10 4 10 6 year range, yet because of itslow abundance ( 81 Kr/Kr 10 -12 ) it has been nearly impossible to measure. However, a newtechnique for measurement of 81 Kr/Kr ratios in small quantities of Kr (as little as 50 micromoles)was recently reported (Atom-Trap Trace Analysis, or ATTA; Chen et al., 1999; Du et al., 2003),and its application to old groundwater was demonstrated successfully by the PI and colleagues intheir NSF-funded study of the Nubian Aquifer, Egypt (Sturchio et al., 2003). That studyestablished the feasibility of using the ATTA technique for routine 81 Kr/Kr measurement inhydrologic investigations of systems having long groundwater residence times. The ATTAtechnique, which can also be used for measuring 85 Kr/Kr, is thus an ideal tool with which toaddress a range of fundamental questions in hydrology.This proposal requests support for a graduate student to work with the PI and colleagues(Z. T. Lu's group at Argonne National Laboratory) in developing further applications of the traceKr isotopes ( 81 Kr and 85 Kr) in hydrologic investigations. The intellectal merit of this research isthat it will lead to an enhanced understanding of the water cycle within the Earth's crust.Specific investigations that we propose are: (1) to determine the residence time of salinegroundwaters in the central U.S.A., which on the basis of stable isotope data are believed to havetraveled more than 1,000 km from a recharge area in the Rocky Mountains (Musgrove andBanner, 1993), and which should therefore have a residence time on the order of 10 6 years; (2) toconstrain the residence time of hydrothermal waters at Yellowstone National Park, for whichlittle information is available (Pearson and Truesdell, 1978); (3) to determine the residence timeof groundwater in the Milk River aquifer of southern Alberta, which was the subject of an earliermulti-tracer study sponsored by the IAEA that was focused on dating very old groundwater(Ivanovich, Frohlich, and Hendry, 1991); and to investigate residence times of young (50 yr)groundwaters where other tracers such as tritium-helium and CFC's do not provide coherentresults. These investigations are representative of the broad range of potential applications oftrace Kr isotopes in groundwater hydrology.The broader impact of the proposed research is that it will provide opportunities forresearch, training, and education at the University of Illinois at Chicago (UIC), which has thenation's fifth most diverse student population; it will establish enhanced local Chicago-areapartnership for routine application of trace Kr isotopes in hydrology, because the Kr separationswill henceforth be performed in a laboratory at UIC (rather than in Switzerland as in the previousNSF-funded study) with ATTA measurements performed nearby at Argonne NationalLaboratory; it will help establish the new subdiscipline of Kr isotope hydrology, which may havesignificant impact on hydrologic investigations and water resources management worldwide.