Quantifying K, U, and Th contents of marine sediments using shipboard natural gamma radiation spectra measured on DV JOIDES Resolution
Quantifying K, U, and Th contents of marine sediments using shipboard natural gamma radiation spectra measured on DV JOIDES Resolution
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DOI：
10.1002/2016gc006715
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发表时间：
2017-03-01
影响因子：
3.5
通讯作者：
Paelike, Heiko
中科院分区：
文献类型：
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作者：
De Vleeschouwer, David;Dunlea, Ann G.;Paelike, Heiko
在国际海洋发现计划（IODP）的考察中，船上产生的数据提供了对岩心序列的第一次洞察。例如，在海洋钻探研究船DV JOIDES Resolution上定期测量回收材料的自然伽马辐射。目前，只有总NGR计数是现成的船上数据，虽然完整的NGR光谱（计数作为伽马射线能级的函数）的生产和存档。这些光谱包含未开发的信息，因为人们可以从K-40、Th-232和U-238放射性衰变系列中同位素的特征伽马射线能量估计钾（K）、钍（Th）和铀（U）的沉积含量。Dunlea等人（2013年）通过在NGR光谱的特定能量水平上积分计数，量化了南太平洋环流沉积物中的K、Th和U含量。然而，由于商业专有的原因，他们研究中使用的算法不适用于更广泛的科学界。在这里，我们提出了一个新的MATLAB算法的量化NGR光谱，是透明的，可供未来的NGR用户。我们证明了算法的性能，通过比较其结果，岸基电感耦合等离子体质谱（ICP-MS），电感耦合等离子体发射光谱（ICP-ES），和定量波长色散X射线荧光（XRF）分析。这些比较的样品来自五次考察中在两个大洋取芯的11个地点（U1341，U1343，U1366-U1369，U1414，U1428-U1430和U1463）。简而言之，我们的算法在IODP考察期间快速生成关于沉积物性质的详细高质量信息，而无需额外成本。
During International Ocean Discovery Program (IODP) expeditions, shipboard-generated data provide the first insights into the cored sequences. The natural gamma radiation (NGR) of the recovered material, for example, is routinely measured on the ocean drilling research vessel DV JOIDES Resolution. At present, only total NGR counts are readily available as shipboard data, although full NGR spectra (counts as a function of gamma-ray energy level) are produced and archived. These spectra contain unexploited information, as one can estimate the sedimentary contents of potassium (K), thorium (Th), and uranium (U) from the characteristic gamma-ray energies of isotopes in the K-40, Th-232, and U-238 radioactive decay series. Dunlea et al. (2013) quantified K, Th, and U contents in sediment from the South Pacific Gyre by integrating counts over specific energy levels of the NGR spectrum. However, the algorithm used in their study is unavailable to the wider scientific community due to commercial proprietary reasons. Here, we present a new MATLAB algorithm for the quantification of NGR spectra that is transparent and accessible to future NGR users. We demonstrate the algorithm's performance by comparing its results to shore-based inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma-emission spectrometry (ICP-ES), and quantitative wavelength-dispersive X-ray fluorescence (XRF) analyses. Samples for these comparisons come from eleven sites (U1341, U1343, U1366-U1369, U1414, U1428-U1430, and U1463) cored in two oceans during five expeditions. In short, our algorithm rapidly produces detailed high-quality information on sediment properties during IODP expeditions at no extra cost.