129I: A New Tracer for Carbon Cycling

129I：一种新的碳循环示踪剂 自核时代开始（约1945年）以来， 活动大大提高了环境水平， 碘（129 I）的放射性同位素。大部分的放射性物质 收集在海洋的表层，那里的水平面 比核爆炸前至少提高了200倍 活动水平。 碘在形成时被结合到有机物中，因此， 增加的129 I活性将伴随着新形成的有机物， 区别于核武器时代。除了在小学期间 生物群中的绝大多数碘都来自于 通过食物链，而不是直接从海水中摄取。 因此，应将正在进行的建设的过去价值记录在 存档的生物标本。 如果，在一个特定的区域，我们可以 记录129I在海洋表层浓度的历史 沃茨和作为碳源的表层海洋生物群中 (and碘）几乎整个食物网下面，那么我们可能是 能够识别所有爆炸后存在的碘的年份 海洋有机物在该地区，从而碘定年 有机物这种方法可以扩展到任何其他 有合适档案的地区。 这项工作将建立过去和现在的129 I值， 墨西哥湾的沃茨。 这些水平低于检测， 所有常用的测量技术，但近似 当加速器质量超过100，000倍时， 采用光谱法（AMS）。香港大学医疗辅助队 罗切斯特将进行这些测量。

129I: A New Tracer For Carbon Cycling Since the beginning of the nuclear age (circa 1945) human activities have greatly increased the environmental levels of the radio-iosotope of iodine (129I). Much of this radioactivity has collected in the surface layers of the ocean, where levels have been raised by at least a factor of 200 above the pre-nuclear activity levels. Iodine is incorporated into organic matter as it forms, so this increased 129I activity will accompany freshly formed organics and distinguish them from pre-nuclear. Except during primary production, the great majority of iodine in the biota is derived through the food chain, and not by direct uptake from seawater. Therefore past values of the ongoing build-up should be recorded in archived biological specimens. If, in a particular region, we can document the history of 129I concentration in the surface ocean waters, and in surface ocean biota that are the source of carbon (and iodine) for almost the entire food web below, then we may be able to identify the year-class of iodine present in all post-bomb marine organic matter in that region, and thereby iodine date the organic matter. This approach could then be extended to any other region where suitable archives exist. This work will establish past and present 129I values within the waters of the Gulf of Mexico. These levels are below detection by all commonly employed measurement techniques but are approximately 100,000 times the sensitivity limits when Accelerator Mass Spectrometry (AMS) is employed. The AMS group of the University of Rochester will make these measurements.