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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Using tree ring cellulose as a tool to estimate past tritium inputs to the ocean
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Using tree ring cellulose as a tool to estimate past tritium inputs to the ocean

机译：使用年轮纤维素作为估算过去past输入海洋的工具

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Tritium (H-3) concentrations in tree rings should reflect ambient precipitation. Thus, to improve knowledge of the H-3 input to the oceans, we developed a new technique to measure H-3 concentrations in annual tree rings. Measurements of H-3 were made on cellulose, the primary constituent of wood, as the isotopic signal of its carbon bound hydrogen atoms should be unchanged since biosynthesis. Traditional cellulose extraction techniques from softwoods are slow and were found to not yield reproducibly pure cellulose. Therefore, a new microwave method was developed which reduces extraction times from 3-5 days to approximately 3 h. Potential H-3 contamination from the hydroxyl groups of the cellulose molecule was subsequently removed by exchange with H-3-free NaOH, thus avoiding the dangers of working with large amounts of cellulose nitrate. The validity of the technique was tested by presenting a H-3 time series from a cedar tree which grew in Tollymore Forest Park, Northern Ireland, for comparison with H-3 data from the Valentia weather station. We find that the H-3 in the cellulose clearly reflects the H-3 in precipitation with no significant smearing of the bomb signal. A simple box model illustrates that the maximum reservoir residence time of source water for the tree is less than 1 yr, suggesting that groundwater is not a major source of water for this tree. In general, however, the groundwater input needs to be quantified for accurate H-3 reconstructions to be made. This work demonstrates the potential of using H-3 in wood cellulose as a proxy for H-3 in precipitation and, thus, opens the door to reconstruction of past H-3 inputs to the ocean. (c) 2005 Elsevier B.V. All rights reserved.
机译：年轮中的rings（H-3）浓度应反映环境降水。因此，为了提高对输入到海洋中的H-3的了解，我们开发了一种新技术来测量年轮中H-3的浓度。 H-3的测量是在纤维素（木材的主要成分）上进行的，因为自生物合成以来，其碳结合氢原子的同位素信号应保持不变。传统的从软木中提取纤维素的技术很慢，并且发现不能生产出可再现的纯纤维素。因此，开发了一种新的微波方法，该方法可将提取时间从3-5天减少到大约3小时。随后，通过与不含H-3的NaOH交换除去了来自纤维素分子羟基的潜在H-3污染，从而避免了使用大量硝酸纤维素的危险。通过显示来自北爱尔兰塔利莫尔森林公园的雪松的H-3时间序列来测试该技术的有效性，以与Valentia气象站的H-3数据进行比较。我们发现纤维素中的H-3清楚地反映了降水中的H-3，而炸弹信号没有明显的拖尾现象。一个简单的盒子模型表明，该树的最大水源停留时间少于1年，这表明地下水不是该树的主要水源。但是，一般而言，需要对地下水输入量进行量化，以进行准确的H-3重建。这项工作证明了在木材纤维素中使用H-3替代降水中H-3的潜力，因此为重建过去向海洋的H-3输入打开了大门。 （c）2005 Elsevier B.V.保留所有权利。

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